media: docs: kAPI docs: move them to driver-api

All those documents describe the media driver API. So, move
them to the right place within the Kernel documentation.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

33 files changed, 4368 insertions, 0 deletions

diff --git a/Documentation/driver-api/media/cec-core.rst b/Documentation/driver-api/media/cec-core.rst
new file mode 100644
index 000000000000..3ce26b7c2b2b
--- /dev/null
+++ b/Documentation/driver-api/media/cec-core.rst
@@ -0,0 +1,474 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+CEC Kernel Support
+==================
+
+The CEC framework provides a unified kernel interface for use with HDMI CEC
+hardware. It is designed to handle a multiple types of hardware (receivers,
+transmitters, USB dongles). The framework also gives the option to decide
+what to do in the kernel driver and what should be handled by userspace
+applications. In addition it integrates the remote control passthrough
+feature into the kernel's remote control framework.
+
+
+The CEC Protocol
+----------------
+
+The CEC protocol enables consumer electronic devices to communicate with each
+other through the HDMI connection. The protocol uses logical addresses in the
+communication. The logical address is strictly connected with the functionality
+provided by the device. The TV acting as the communication hub is always
+assigned address 0. The physical address is determined by the physical
+connection between devices.
+
+The CEC framework described here is up to date with the CEC 2.0 specification.
+It is documented in the HDMI 1.4 specification with the new 2.0 bits documented
+in the HDMI 2.0 specification. But for most of the features the freely available
+HDMI 1.3a specification is sufficient:
+
+http://www.microprocessor.org/HDMISpecification13a.pdf
+
+
+CEC Adapter Interface
+---------------------
+
+The struct cec_adapter represents the CEC adapter hardware. It is created by
+calling cec_allocate_adapter() and deleted by calling cec_delete_adapter():
+
+.. c:function::
+   struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops, void *priv,
+   const char *name, u32 caps, u8 available_las);
+
+.. c:function::
+   void cec_delete_adapter(struct cec_adapter *adap);
+
+To create an adapter you need to pass the following information:
+
+ops:
+	adapter operations which are called by the CEC framework and that you
+	have to implement.
+
+priv:
+	will be stored in adap->priv and can be used by the adapter ops.
+	Use cec_get_drvdata(adap) to get the priv pointer.
+
+name:
+	the name of the CEC adapter. Note: this name will be copied.
+
+caps:
+	capabilities of the CEC adapter. These capabilities determine the
+	capabilities of the hardware and which parts are to be handled
+	by userspace and which parts are handled by kernelspace. The
+	capabilities are returned by CEC_ADAP_G_CAPS.
+
+available_las:
+	the number of simultaneous logical addresses that this
+	adapter can handle. Must be 1 <= available_las <= CEC_MAX_LOG_ADDRS.
+
+To obtain the priv pointer use this helper function:
+
+.. c:function::
+	void *cec_get_drvdata(const struct cec_adapter *adap);
+
+To register the /dev/cecX device node and the remote control device (if
+CEC_CAP_RC is set) you call:
+
+.. c:function::
+	int cec_register_adapter(struct cec_adapter *adap, struct device *parent);
+
+where parent is the parent device.
+
+To unregister the devices call:
+
+.. c:function::
+	void cec_unregister_adapter(struct cec_adapter *adap);
+
+Note: if cec_register_adapter() fails, then call cec_delete_adapter() to
+clean up. But if cec_register_adapter() succeeded, then only call
+cec_unregister_adapter() to clean up, never cec_delete_adapter(). The
+unregister function will delete the adapter automatically once the last user
+of that /dev/cecX device has closed its file handle.
+
+
+Implementing the Low-Level CEC Adapter
+--------------------------------------
+
+The following low-level adapter operations have to be implemented in
+your driver:
+
+.. c:type:: struct cec_adap_ops
+
+.. code-block:: none
+
+	struct cec_adap_ops
+	{
+		/* Low-level callbacks */
+		int (*adap_enable)(struct cec_adapter *adap, bool enable);
+		int (*adap_monitor_all_enable)(struct cec_adapter *adap, bool enable);
+		int (*adap_monitor_pin_enable)(struct cec_adapter *adap, bool enable);
+		int (*adap_log_addr)(struct cec_adapter *adap, u8 logical_addr);
+		int (*adap_transmit)(struct cec_adapter *adap, u8 attempts,
+				      u32 signal_free_time, struct cec_msg *msg);
+		void (*adap_status)(struct cec_adapter *adap, struct seq_file *file);
+		void (*adap_free)(struct cec_adapter *adap);
+
+		/* Error injection callbacks */
+		...
+
+		/* High-level callbacks */
+		...
+	};
+
+The seven low-level ops deal with various aspects of controlling the CEC adapter
+hardware:
+
+
+To enable/disable the hardware:
+
+.. c:function::
+	int (*adap_enable)(struct cec_adapter *adap, bool enable);
+
+This callback enables or disables the CEC hardware. Enabling the CEC hardware
+means powering it up in a state where no logical addresses are claimed. This
+op assumes that the physical address (adap->phys_addr) is valid when enable is
+true and will not change while the CEC adapter remains enabled. The initial
+state of the CEC adapter after calling cec_allocate_adapter() is disabled.
+
+Note that adap_enable must return 0 if enable is false.
+
+
+To enable/disable the 'monitor all' mode:
+
+.. c:function::
+	int (*adap_monitor_all_enable)(struct cec_adapter *adap, bool enable);
+
+If enabled, then the adapter should be put in a mode to also monitor messages
+that not for us. Not all hardware supports this and this function is only
+called if the CEC_CAP_MONITOR_ALL capability is set. This callback is optional
+(some hardware may always be in 'monitor all' mode).
+
+Note that adap_monitor_all_enable must return 0 if enable is false.
+
+
+To enable/disable the 'monitor pin' mode:
+
+.. c:function::
+	int (*adap_monitor_pin_enable)(struct cec_adapter *adap, bool enable);
+
+If enabled, then the adapter should be put in a mode to also monitor CEC pin
+changes. Not all hardware supports this and this function is only called if
+the CEC_CAP_MONITOR_PIN capability is set. This callback is optional
+(some hardware may always be in 'monitor pin' mode).
+
+Note that adap_monitor_pin_enable must return 0 if enable is false.
+
+
+To program a new logical address:
+
+.. c:function::
+	int (*adap_log_addr)(struct cec_adapter *adap, u8 logical_addr);
+
+If logical_addr == CEC_LOG_ADDR_INVALID then all programmed logical addresses
+are to be erased. Otherwise the given logical address should be programmed.
+If the maximum number of available logical addresses is exceeded, then it
+should return -ENXIO. Once a logical address is programmed the CEC hardware
+can receive directed messages to that address.
+
+Note that adap_log_addr must return 0 if logical_addr is CEC_LOG_ADDR_INVALID.
+
+
+To transmit a new message:
+
+.. c:function::
+	int (*adap_transmit)(struct cec_adapter *adap, u8 attempts,
+			     u32 signal_free_time, struct cec_msg *msg);
+
+This transmits a new message. The attempts argument is the suggested number of
+attempts for the transmit.
+
+The signal_free_time is the number of data bit periods that the adapter should
+wait when the line is free before attempting to send a message. This value
+depends on whether this transmit is a retry, a message from a new initiator or
+a new message for the same initiator. Most hardware will handle this
+automatically, but in some cases this information is needed.
+
+The CEC_FREE_TIME_TO_USEC macro can be used to convert signal_free_time to
+microseconds (one data bit period is 2.4 ms).
+
+
+To log the current CEC hardware status:
+
+.. c:function::
+	void (*adap_status)(struct cec_adapter *adap, struct seq_file *file);
+
+This optional callback can be used to show the status of the CEC hardware.
+The status is available through debugfs: cat /sys/kernel/debug/cec/cecX/status
+
+To free any resources when the adapter is deleted:
+
+.. c:function::
+	void (*adap_free)(struct cec_adapter *adap);
+
+This optional callback can be used to free any resources that might have been
+allocated by the driver. It's called from cec_delete_adapter.
+
+
+Your adapter driver will also have to react to events (typically interrupt
+driven) by calling into the framework in the following situations:
+
+When a transmit finished (successfully or otherwise):
+
+.. c:function::
+	void cec_transmit_done(struct cec_adapter *adap, u8 status, u8 arb_lost_cnt,
+		       u8 nack_cnt, u8 low_drive_cnt, u8 error_cnt);
+
+or:
+
+.. c:function::
+	void cec_transmit_attempt_done(struct cec_adapter *adap, u8 status);
+
+The status can be one of:
+
+CEC_TX_STATUS_OK:
+	the transmit was successful.
+
+CEC_TX_STATUS_ARB_LOST:
+	arbitration was lost: another CEC initiator
+	took control of the CEC line and you lost the arbitration.
+
+CEC_TX_STATUS_NACK:
+	the message was nacked (for a directed message) or
+	acked (for a broadcast message). A retransmission is needed.
+
+CEC_TX_STATUS_LOW_DRIVE:
+	low drive was detected on the CEC bus. This indicates that
+	a follower detected an error on the bus and requested a
+	retransmission.
+
+CEC_TX_STATUS_ERROR:
+	some unspecified error occurred: this can be one of ARB_LOST
+	or LOW_DRIVE if the hardware cannot differentiate or something
+	else entirely. Some hardware only supports OK and FAIL as the
+	result of a transmit, i.e. there is no way to differentiate
+	between the different possible errors. In that case map FAIL
+	to CEC_TX_STATUS_NACK and not to CEC_TX_STATUS_ERROR.
+
+CEC_TX_STATUS_MAX_RETRIES:
+	could not transmit the message after trying multiple times.
+	Should only be set by the driver if it has hardware support for
+	retrying messages. If set, then the framework assumes that it
+	doesn't have to make another attempt to transmit the message
+	since the hardware did that already.
+
+The hardware must be able to differentiate between OK, NACK and 'something
+else'.
+
+The \*_cnt arguments are the number of error conditions that were seen.
+This may be 0 if no information is available. Drivers that do not support
+hardware retry can just set the counter corresponding to the transmit error
+to 1, if the hardware does support retry then either set these counters to
+0 if the hardware provides no feedback of which errors occurred and how many
+times, or fill in the correct values as reported by the hardware.
+
+Be aware that calling these functions can immediately start a new transmit
+if there is one pending in the queue. So make sure that the hardware is in
+a state where new transmits can be started *before* calling these functions.
+
+The cec_transmit_attempt_done() function is a helper for cases where the
+hardware never retries, so the transmit is always for just a single
+attempt. It will call cec_transmit_done() in turn, filling in 1 for the
+count argument corresponding to the status. Or all 0 if the status was OK.
+
+When a CEC message was received:
+
+.. c:function::
+	void cec_received_msg(struct cec_adapter *adap, struct cec_msg *msg);
+
+Speaks for itself.
+
+Implementing the interrupt handler
+----------------------------------
+
+Typically the CEC hardware provides interrupts that signal when a transmit
+finished and whether it was successful or not, and it provides and interrupt
+when a CEC message was received.
+
+The CEC driver should always process the transmit interrupts first before
+handling the receive interrupt. The framework expects to see the cec_transmit_done
+call before the cec_received_msg call, otherwise it can get confused if the
+received message was in reply to the transmitted message.
+
+Optional: Implementing Error Injection Support
+----------------------------------------------
+
+If the CEC adapter supports Error Injection functionality, then that can
+be exposed through the Error Injection callbacks:
+
+.. code-block:: none
+
+	struct cec_adap_ops {
+		/* Low-level callbacks */
+		...
+
+		/* Error injection callbacks */
+		int (*error_inj_show)(struct cec_adapter *adap, struct seq_file *sf);
+		bool (*error_inj_parse_line)(struct cec_adapter *adap, char *line);
+
+		/* High-level CEC message callback */
+		...
+	};
+
+If both callbacks are set, then an ``error-inj`` file will appear in debugfs.
+The basic syntax is as follows:
+
+Leading spaces/tabs are ignored. If the next character is a ``#`` or the end of the
+line was reached, then the whole line is ignored. Otherwise a command is expected.
+
+This basic parsing is done in the CEC Framework. It is up to the driver to decide
+what commands to implement. The only requirement is that the command ``clear`` without
+any arguments must be implemented and that it will remove all current error injection
+commands.
+
+This ensures that you can always do ``echo clear >error-inj`` to clear any error
+injections without having to know the details of the driver-specific commands.
+
+Note that the output of ``error-inj`` shall be valid as input to ``error-inj``.
+So this must work:
+
+.. code-block:: none
+
+	$ cat error-inj >einj.txt
+	$ cat einj.txt >error-inj
+
+The first callback is called when this file is read and it should show the
+the current error injection state:
+
+.. c:function::
+	int (*error_inj_show)(struct cec_adapter *adap, struct seq_file *sf);
+
+It is recommended that it starts with a comment block with basic usage
+information. It returns 0 for success and an error otherwise.
+
+The second callback will parse commands written to the ``error-inj`` file:
+
+.. c:function::
+	bool (*error_inj_parse_line)(struct cec_adapter *adap, char *line);
+
+The ``line`` argument points to the start of the command. Any leading
+spaces or tabs have already been skipped. It is a single line only (so there
+are no embedded newlines) and it is 0-terminated. The callback is free to
+modify the contents of the buffer. It is only called for lines containing a
+command, so this callback is never called for empty lines or comment lines.
+
+Return true if the command was valid or false if there were syntax errors.
+
+Implementing the High-Level CEC Adapter
+---------------------------------------
+
+The low-level operations drive the hardware, the high-level operations are
+CEC protocol driven. The following high-level callbacks are available:
+
+.. code-block:: none
+
+	struct cec_adap_ops {
+		/* Low-level callbacks */
+		...
+
+		/* Error injection callbacks */
+		...
+
+		/* High-level CEC message callback */
+		int (*received)(struct cec_adapter *adap, struct cec_msg *msg);
+	};
+
+The received() callback allows the driver to optionally handle a newly
+received CEC message
+
+.. c:function::
+	int (*received)(struct cec_adapter *adap, struct cec_msg *msg);
+
+If the driver wants to process a CEC message, then it can implement this
+callback. If it doesn't want to handle this message, then it should return
+-ENOMSG, otherwise the CEC framework assumes it processed this message and
+it will not do anything with it.
+
+
+CEC framework functions
+-----------------------
+
+CEC Adapter drivers can call the following CEC framework functions:
+
+.. c:function::
+	int cec_transmit_msg(struct cec_adapter *adap, struct cec_msg *msg,
+			     bool block);
+
+Transmit a CEC message. If block is true, then wait until the message has been
+transmitted, otherwise just queue it and return.
+
+.. c:function::
+	void cec_s_phys_addr(struct cec_adapter *adap, u16 phys_addr,
+			     bool block);
+
+Change the physical address. This function will set adap->phys_addr and
+send an event if it has changed. If cec_s_log_addrs() has been called and
+the physical address has become valid, then the CEC framework will start
+claiming the logical addresses. If block is true, then this function won't
+return until this process has finished.
+
+When the physical address is set to a valid value the CEC adapter will
+be enabled (see the adap_enable op). When it is set to CEC_PHYS_ADDR_INVALID,
+then the CEC adapter will be disabled. If you change a valid physical address
+to another valid physical address, then this function will first set the
+address to CEC_PHYS_ADDR_INVALID before enabling the new physical address.
+
+.. c:function::
+	void cec_s_phys_addr_from_edid(struct cec_adapter *adap,
+				       const struct edid *edid);
+
+A helper function that extracts the physical address from the edid struct
+and calls cec_s_phys_addr() with that address, or CEC_PHYS_ADDR_INVALID
+if the EDID did not contain a physical address or edid was a NULL pointer.
+
+.. c:function::
+	int cec_s_log_addrs(struct cec_adapter *adap,
+			    struct cec_log_addrs *log_addrs, bool block);
+
+Claim the CEC logical addresses. Should never be called if CEC_CAP_LOG_ADDRS
+is set. If block is true, then wait until the logical addresses have been
+claimed, otherwise just queue it and return. To unconfigure all logical
+addresses call this function with log_addrs set to NULL or with
+log_addrs->num_log_addrs set to 0. The block argument is ignored when
+unconfiguring. This function will just return if the physical address is
+invalid. Once the physical address becomes valid, then the framework will
+attempt to claim these logical addresses.
+
+CEC Pin framework
+-----------------
+
+Most CEC hardware operates on full CEC messages where the software provides
+the message and the hardware handles the low-level CEC protocol. But some
+hardware only drives the CEC pin and software has to handle the low-level
+CEC protocol. The CEC pin framework was created to handle such devices.
+
+Note that due to the close-to-realtime requirements it can never be guaranteed
+to work 100%. This framework uses highres timers internally, but if a
+timer goes off too late by more than 300 microseconds wrong results can
+occur. In reality it appears to be fairly reliable.
+
+One advantage of this low-level implementation is that it can be used as
+a cheap CEC analyser, especially if interrupts can be used to detect
+CEC pin transitions from low to high or vice versa.
+
+.. kernel-doc:: include/media/cec-pin.h
+
+CEC Notifier framework
+----------------------
+
+Most drm HDMI implementations have an integrated CEC implementation and no
+notifier support is needed. But some have independent CEC implementations
+that have their own driver. This could be an IP block for an SoC or a
+completely separate chip that deals with the CEC pin. For those cases a
+drm driver can install a notifier and use the notifier to inform the
+CEC driver about changes in the physical address.
+
+.. kernel-doc:: include/media/cec-notifier.h
diff --git a/Documentation/driver-api/media/csi2.rst b/Documentation/driver-api/media/csi2.rst
new file mode 100644
index 000000000000..e111ff7bfd3d
--- /dev/null
+++ b/Documentation/driver-api/media/csi2.rst
@@ -0,0 +1,85 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+MIPI CSI-2
+==========
+
+CSI-2 is a data bus intended for transferring images from cameras to
+the host SoC. It is defined by the `MIPI alliance`_.
+
+.. _`MIPI alliance`: http://www.mipi.org/
+
+Transmitter drivers
+-------------------
+
+CSI-2 transmitter, such as a sensor or a TV tuner, drivers need to
+provide the CSI-2 receiver with information on the CSI-2 bus
+configuration. These include the V4L2_CID_LINK_FREQ and
+V4L2_CID_PIXEL_RATE controls and
+(:c:type:`v4l2_subdev_video_ops`->s_stream() callback). These
+interface elements must be present on the sub-device represents the
+CSI-2 transmitter.
+
+The V4L2_CID_LINK_FREQ control is used to tell the receiver driver the
+frequency (and not the symbol rate) of the link. The
+V4L2_CID_PIXEL_RATE is may be used by the receiver to obtain the pixel
+rate the transmitter uses. The
+:c:type:`v4l2_subdev_video_ops`->s_stream() callback provides an
+ability to start and stop the stream.
+
+The value of the V4L2_CID_PIXEL_RATE is calculated as follows::
+
+	pixel_rate = link_freq * 2 * nr_of_lanes / bits_per_sample
+
+where
+
+.. list-table:: variables in pixel rate calculation
+   :header-rows: 1
+
+   * - variable or constant
+     - description
+   * - link_freq
+     - The value of the V4L2_CID_LINK_FREQ integer64 menu item.
+   * - nr_of_lanes
+     - Number of data lanes used on the CSI-2 link. This can
+       be obtained from the OF endpoint configuration.
+   * - 2
+     - Two bits are transferred per clock cycle per lane.
+   * - bits_per_sample
+     - Number of bits per sample.
+
+The transmitter drivers must, if possible, configure the CSI-2
+transmitter to *LP-11 mode* whenever the transmitter is powered on but
+not active, and maintain *LP-11 mode* until stream on. Only at stream
+on should the transmitter activate the clock on the clock lane and
+transition to *HS mode*.
+
+Some transmitters do this automatically but some have to be explicitly
+programmed to do so, and some are unable to do so altogether due to
+hardware constraints.
+
+Stopping the transmitter
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+A transmitter stops sending the stream of images as a result of
+calling the ``.s_stream()`` callback. Some transmitters may stop the
+stream at a frame boundary whereas others stop immediately,
+effectively leaving the current frame unfinished. The receiver driver
+should not make assumptions either way, but function properly in both
+cases.
+
+Receiver drivers
+----------------
+
+Before the receiver driver may enable the CSI-2 transmitter by using
+the :c:type:`v4l2_subdev_video_ops`->s_stream(), it must have powered
+the transmitter up by using the
+:c:type:`v4l2_subdev_core_ops`->s_power() callback. This may take
+place either indirectly by using :c:func:`v4l2_pipeline_pm_get` or
+directly.
+
+Formats
+-------
+
+The media bus pixel codes document parallel formats. Should the pixel data be
+transported over a serial bus, the media bus pixel code that describes a
+parallel format that transfers a sample on a single clock cycle is used.
diff --git a/Documentation/driver-api/media/dtv-ca.rst b/Documentation/driver-api/media/dtv-ca.rst
new file mode 100644
index 000000000000..8a09862b428b
--- /dev/null
+++ b/Documentation/driver-api/media/dtv-ca.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Digital TV Conditional Access kABI
+----------------------------------
+
+.. kernel-doc:: include/media/dvb_ca_en50221.h
diff --git a/Documentation/driver-api/media/dtv-common.rst b/Documentation/driver-api/media/dtv-common.rst
new file mode 100644
index 000000000000..f8b2c4dc8170
--- /dev/null
+++ b/Documentation/driver-api/media/dtv-common.rst
@@ -0,0 +1,62 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Digital TV Common functions
+---------------------------
+
+Math functions
+~~~~~~~~~~~~~~
+
+Provide some commonly-used math functions, usually required in order to
+estimate signal strength and signal to noise measurements in dB.
+
+.. kernel-doc:: include/media/dvb_math.h
+
+
+DVB devices
+~~~~~~~~~~~
+
+Those functions are responsible for handling the DVB device nodes.
+
+.. kernel-doc:: include/media/dvbdev.h
+
+Digital TV Ring buffer
+~~~~~~~~~~~~~~~~~~~~~~
+
+Those routines implement ring buffers used to handle digital TV data and
+copy it from/to userspace.
+
+.. note::
+
+  1) For performance reasons read and write routines don't check buffer sizes
+     and/or number of bytes free/available. This has to be done before these
+     routines are called. For example:
+
+   .. code-block:: c
+
+        /* write @buflen: bytes */
+        free = dvb_ringbuffer_free(rbuf);
+        if (free >= buflen)
+                count = dvb_ringbuffer_write(rbuf, buffer, buflen);
+        else
+                /* do something */
+
+        /* read min. 1000, max. @bufsize: bytes */
+        avail = dvb_ringbuffer_avail(rbuf);
+        if (avail >= 1000)
+                count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize));
+        else
+                /* do something */
+
+  2) If there is exactly one reader and one writer, there is no need
+     to lock read or write operations.
+     Two or more readers must be locked against each other.
+     Flushing the buffer counts as a read operation.
+     Resetting the buffer counts as a read and write operation.
+     Two or more writers must be locked against each other.
+
+.. kernel-doc:: include/media/dvb_ringbuffer.h
+
+Digital TV VB2 handler
+~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/media/dvb_vb2.h
diff --git a/Documentation/driver-api/media/dtv-core.rst b/Documentation/driver-api/media/dtv-core.rst
new file mode 100644
index 000000000000..82c5b85ed9b1
--- /dev/null
+++ b/Documentation/driver-api/media/dtv-core.rst
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Digital TV (DVB) devices
+------------------------
+
+Digital TV devices are implemented by several different drivers:
+
+- A bridge driver that is responsible to talk with the bus where the other
+  devices are connected (PCI, USB, SPI), bind to the other drivers and
+  implement the digital demux logic (either in software or in hardware);
+
+- Frontend drivers that are usually implemented as two separate drivers:
+
+  - A tuner driver that implements the logic which commands the part of
+    the hardware responsible for tuning into a digital TV transponder or
+    physical channel. The output of a tuner is usually a baseband or
+    Intermediate Frequency (IF) signal;
+
+  - A demodulator driver (a.k.a "demod") that implements the logic which
+    commands the digital TV decoding hardware. The output of a demod is
+    a digital stream, with multiple audio, video and data channels typically
+    multiplexed using MPEG Transport Stream [#f1]_.
+
+On most hardware, the frontend drivers talk with the bridge driver using an
+I2C bus.
+
+.. [#f1] Some standards use TCP/IP for multiplexing data, like DVB-H (an
+   abandoned standard, not used anymore) and ATSC version 3.0 current
+   proposals. Currently, the DVB subsystem doesn't implement those standards.
+
+
+.. toctree::
+    :maxdepth: 1
+
+    dtv-common
+    dtv-frontend
+    dtv-demux
+    dtv-ca
+    dtv-net
diff --git a/Documentation/driver-api/media/dtv-demux.rst b/Documentation/driver-api/media/dtv-demux.rst
new file mode 100644
index 000000000000..c0ae5dec5328
--- /dev/null
+++ b/Documentation/driver-api/media/dtv-demux.rst
@@ -0,0 +1,84 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Digital TV Demux kABI
+---------------------
+
+Digital TV Demux
+~~~~~~~~~~~~~~~~
+
+The Kernel Digital TV Demux kABI defines a driver-internal interface for
+registering low-level, hardware specific driver to a hardware independent
+demux layer. It is only of interest for Digital TV device driver writers.
+The header file for this kABI is named ``demux.h`` and located in
+``include/media``.
+
+The demux kABI should be implemented for each demux in the system. It is
+used to select the TS source of a demux and to manage the demux resources.
+When the demux client allocates a resource via the demux kABI, it receives
+a pointer to the kABI of that resource.
+
+Each demux receives its TS input from a DVB front-end or from memory, as
+set via this demux kABI. In a system with more than one front-end, the kABI
+can be used to select one of the DVB front-ends as a TS source for a demux,
+unless this is fixed in the HW platform.
+
+The demux kABI only controls front-ends regarding to their connections with
+demuxes; the kABI used to set the other front-end parameters, such as
+tuning, are devined via the Digital TV Frontend kABI.
+
+The functions that implement the abstract interface demux should be defined
+static or module private and registered to the Demux core for external
+access. It is not necessary to implement every function in the struct
+:c:type:`dmx_demux`. For example, a demux interface might support Section filtering,
+but not PES filtering. The kABI client is expected to check the value of any
+function pointer before calling the function: the value of ``NULL`` means
+that the function is not available.
+
+Whenever the functions of the demux API modify shared data, the
+possibilities of lost update and race condition problems should be
+addressed, e.g. by protecting parts of code with mutexes.
+
+Note that functions called from a bottom half context must not sleep.
+Even a simple memory allocation without using ``GFP_ATOMIC`` can result in a
+kernel thread being put to sleep if swapping is needed. For example, the
+Linux Kernel calls the functions of a network device interface from a
+bottom half context. Thus, if a demux kABI function is called from network
+device code, the function must not sleep.
+
+Demux Callback API
+~~~~~~~~~~~~~~~~~~
+
+This kernel-space API comprises the callback functions that deliver filtered
+data to the demux client. Unlike the other DVB kABIs, these functions are
+provided by the client and called from the demux code.
+
+The function pointers of this abstract interface are not packed into a
+structure as in the other demux APIs, because the callback functions are
+registered and used independent of each other. As an example, it is possible
+for the API client to provide several callback functions for receiving TS
+packets and no callbacks for PES packets or sections.
+
+The functions that implement the callback API need not be re-entrant: when
+a demux driver calls one of these functions, the driver is not allowed to
+call the function again before the original call returns. If a callback is
+triggered by a hardware interrupt, it is recommended to use the Linux
+bottom half mechanism or start a tasklet instead of making the callback
+function call directly from a hardware interrupt.
+
+This mechanism is implemented by :c:func:`dmx_ts_cb()` and :c:func:`dmx_section_cb()`
+callbacks.
+
+Digital TV Demux device registration functions and data structures
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/media/dmxdev.h
+
+High-level Digital TV demux interface
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/media/dvb_demux.h
+
+Driver-internal low-level hardware specific driver demux interface
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/media/demux.h
diff --git a/Documentation/driver-api/media/dtv-frontend.rst b/Documentation/driver-api/media/dtv-frontend.rst
new file mode 100644
index 000000000000..b362109bb131
--- /dev/null
+++ b/Documentation/driver-api/media/dtv-frontend.rst
@@ -0,0 +1,445 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Digital TV Frontend kABI
+------------------------
+
+Digital TV Frontend
+~~~~~~~~~~~~~~~~~~~
+
+The Digital TV Frontend kABI defines a driver-internal interface for
+registering low-level, hardware specific driver to a hardware independent
+frontend layer. It is only of interest for Digital TV device driver writers.
+The header file for this API is named ``dvb_frontend.h`` and located in
+``include/media/``.
+
+Demodulator driver
+^^^^^^^^^^^^^^^^^^
+
+The demodulator driver is responsible for talking with the decoding part of the
+hardware. Such driver should implement :c:type:`dvb_frontend_ops`, which
+tells what type of digital TV standards are supported, and points to a
+series of functions that allow the DVB core to command the hardware via
+the code under ``include/media/dvb_frontend.c``.
+
+A typical example of such struct in a driver ``foo`` is::
+
+	static struct dvb_frontend_ops foo_ops = {
+		.delsys = { SYS_DVBT, SYS_DVBT2, SYS_DVBC_ANNEX_A },
+		.info = {
+			.name	= "foo DVB-T/T2/C driver",
+			.caps = FE_CAN_FEC_1_2 |
+				FE_CAN_FEC_2_3 |
+				FE_CAN_FEC_3_4 |
+				FE_CAN_FEC_5_6 |
+				FE_CAN_FEC_7_8 |
+				FE_CAN_FEC_AUTO |
+				FE_CAN_QPSK |
+				FE_CAN_QAM_16 |
+				FE_CAN_QAM_32 |
+				FE_CAN_QAM_64 |
+				FE_CAN_QAM_128 |
+				FE_CAN_QAM_256 |
+				FE_CAN_QAM_AUTO |
+				FE_CAN_TRANSMISSION_MODE_AUTO |
+				FE_CAN_GUARD_INTERVAL_AUTO |
+				FE_CAN_HIERARCHY_AUTO |
+				FE_CAN_MUTE_TS |
+				FE_CAN_2G_MODULATION,
+			.frequency_min = 42000000, /* Hz */
+			.frequency_max = 1002000000, /* Hz */
+			.symbol_rate_min = 870000,
+			.symbol_rate_max = 11700000
+		},
+		.init = foo_init,
+		.sleep = foo_sleep,
+		.release = foo_release,
+		.set_frontend = foo_set_frontend,
+		.get_frontend = foo_get_frontend,
+		.read_status = foo_get_status_and_stats,
+		.tune = foo_tune,
+		.i2c_gate_ctrl = foo_i2c_gate_ctrl,
+		.get_frontend_algo = foo_get_algo,
+	};
+
+A typical example of such struct in a driver ``bar`` meant to be used on
+Satellite TV reception is::
+
+	static const struct dvb_frontend_ops bar_ops = {
+		.delsys = { SYS_DVBS, SYS_DVBS2 },
+		.info = {
+			.name		= "Bar DVB-S/S2 demodulator",
+			.frequency_min	= 500000, /* KHz */
+			.frequency_max	= 2500000, /* KHz */
+			.frequency_stepsize	= 0,
+			.symbol_rate_min = 1000000,
+			.symbol_rate_max = 45000000,
+			.symbol_rate_tolerance = 500,
+			.caps = FE_CAN_INVERSION_AUTO |
+				FE_CAN_FEC_AUTO |
+				FE_CAN_QPSK,
+		},
+		.init = bar_init,
+		.sleep = bar_sleep,
+		.release = bar_release,
+		.set_frontend = bar_set_frontend,
+		.get_frontend = bar_get_frontend,
+		.read_status = bar_get_status_and_stats,
+		.i2c_gate_ctrl = bar_i2c_gate_ctrl,
+		.get_frontend_algo = bar_get_algo,
+		.tune = bar_tune,
+
+		/* Satellite-specific */
+		.diseqc_send_master_cmd = bar_send_diseqc_msg,
+		.diseqc_send_burst = bar_send_burst,
+		.set_tone = bar_set_tone,
+		.set_voltage = bar_set_voltage,
+	};
+
+.. note::
+
+   #) For satellite digital TV standards (DVB-S, DVB-S2, ISDB-S), the
+      frequencies are specified in kHz, while, for terrestrial and cable
+      standards, they're specified in Hz. Due to that, if the same frontend
+      supports both types, you'll need to have two separate
+      :c:type:`dvb_frontend_ops` structures, one for each standard.
+   #) The ``.i2c_gate_ctrl`` field is present only when the hardware has
+      allows controlling an I2C gate (either directly of via some GPIO pin),
+      in order to remove the tuner from the I2C bus after a channel is
+      tuned.
+   #) All new drivers should implement the
+      :ref:`DVBv5 statistics <dvbv5_stats>` via ``.read_status``.
+      Yet, there are a number of callbacks meant to get statistics for
+      signal strength, S/N and UCB. Those are there to provide backward
+      compatibility with legacy applications that don't support the DVBv5
+      API. Implementing those callbacks are optional. Those callbacks may be
+      removed in the future, after we have all existing drivers supporting
+      DVBv5 stats.
+   #) Other callbacks are required for satellite TV standards, in order to
+      control LNBf and DiSEqC: ``.diseqc_send_master_cmd``,
+      ``.diseqc_send_burst``, ``.set_tone``, ``.set_voltage``.
+
+.. |delta|   unicode:: U+00394
+
+The ``include/media/dvb_frontend.c`` has a kernel thread which is
+responsible for tuning the device. It supports multiple algorithms to
+detect a channel, as defined at enum :c:func:`dvbfe_algo`.
+
+The algorithm to be used is obtained via ``.get_frontend_algo``. If the driver
+doesn't fill its field at struct :c:type:`dvb_frontend_ops`, it will default to
+``DVBFE_ALGO_SW``, meaning that the dvb-core will do a zigzag when tuning,
+e. g. it will try first to use the specified center frequency ``f``,
+then, it will do ``f`` + |delta|, ``f`` - |delta|, ``f`` + 2 x |delta|,
+``f`` - 2 x |delta| and so on.
+
+If the hardware has internally a some sort of zigzag algorithm, you should
+define a ``.get_frontend_algo`` function that would return ``DVBFE_ALGO_HW``.
+
+.. note::
+
+   The core frontend support also supports
+   a third type (``DVBFE_ALGO_CUSTOM``), in order to allow the driver to
+   define its own hardware-assisted algorithm. Very few hardware need to
+   use it nowadays. Using ``DVBFE_ALGO_CUSTOM`` require to provide other
+   function callbacks at struct :c:type:`dvb_frontend_ops`.
+
+Attaching frontend driver to the bridge driver
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Before using the Digital TV frontend core, the bridge driver should attach
+the frontend demod, tuner and SEC devices and call
+:c:func:`dvb_register_frontend()`,
+in order to register the new frontend at the subsystem. At device
+detach/removal, the bridge driver should call
+:c:func:`dvb_unregister_frontend()` to
+remove the frontend from the core and then :c:func:`dvb_frontend_detach()`
+to free the memory allocated by the frontend drivers.
+
+The drivers should also call :c:func:`dvb_frontend_suspend()` as part of
+their handler for the :c:type:`device_driver`.\ ``suspend()``, and
+:c:func:`dvb_frontend_resume()` as
+part of their handler for :c:type:`device_driver`.\ ``resume()``.
+
+A few other optional functions are provided to handle some special cases.
+
+.. _dvbv5_stats:
+
+Digital TV Frontend statistics
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Introduction
+^^^^^^^^^^^^
+
+Digital TV frontends provide a range of
+:ref:`statistics <frontend-stat-properties>` meant to help tuning the device
+and measuring the quality of service.
+
+For each statistics measurement, the driver should set the type of scale used,
+or ``FE_SCALE_NOT_AVAILABLE`` if the statistics is not available on a given
+time. Drivers should also provide the number of statistics for each type.
+that's usually 1 for most video standards [#f2]_.
+
+Drivers should initialize each statistic counters with length and
+scale at its init code. For example, if the frontend provides signal
+strength, it should have, on its init code::
+
+	struct dtv_frontend_properties *c = &state->fe.dtv_property_cache;
+
+	c->strength.len = 1;
+	c->strength.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
+
+And, when the statistics got updated, set the scale::
+
+	c->strength.stat[0].scale = FE_SCALE_DECIBEL;
+	c->strength.stat[0].uvalue = strength;
+
+.. [#f2] For ISDB-T, it may provide both a global statistics and a per-layer
+   set of statistics. On such cases, len should be equal to 4. The first
+   value corresponds to the global stat; the other ones to each layer, e. g.:
+
+   - c->cnr.stat[0] for global S/N carrier ratio,
+   - c->cnr.stat[1] for Layer A S/N carrier ratio,
+   - c->cnr.stat[2] for layer B S/N carrier ratio,
+   - c->cnr.stat[3] for layer C S/N carrier ratio.
+
+.. note:: Please prefer to use ``FE_SCALE_DECIBEL`` instead of
+   ``FE_SCALE_RELATIVE`` for signal strength and CNR measurements.
+
+Groups of statistics
+^^^^^^^^^^^^^^^^^^^^
+
+There are several groups of statistics currently supported:
+
+Signal strength (:ref:`DTV-STAT-SIGNAL-STRENGTH`)
+  - Measures the signal strength level at the analog part of the tuner or
+    demod.
+
+  - Typically obtained from the gain applied to the tuner and/or frontend
+    in order to detect the carrier. When no carrier is detected, the gain is
+    at the maximum value (so, strength is on its minimal).
+
+  - As the gain is visible through the set of registers that adjust the gain,
+    typically, this statistics is always available [#f3]_.
+
+  - Drivers should try to make it available all the times, as these statistics
+    can be used when adjusting an antenna position and to check for troubles
+    at the cabling.
+
+  .. [#f3] On a few devices, the gain keeps floating if there is no carrier.
+     On such devices, strength report should check first if carrier is
+     detected at the tuner (``FE_HAS_CARRIER``, see :c:type:`fe_status`),
+     and otherwise return the lowest possible value.
+
+Carrier Signal to Noise ratio (:ref:`DTV-STAT-CNR`)
+  - Signal to Noise ratio for the main carrier.
+
+  - Signal to Noise measurement depends on the device. On some hardware, it is
+    available when the main carrier is detected. On those hardware, CNR
+    measurement usually comes from the tuner (e. g. after ``FE_HAS_CARRIER``,
+    see :c:type:`fe_status`).
+
+    On other devices, it requires inner FEC decoding,
+    as the frontend measures it indirectly from other parameters (e. g. after
+    ``FE_HAS_VITERBI``, see :c:type:`fe_status`).
+
+    Having it available after inner FEC is more common.
+
+Bit counts post-FEC (:ref:`DTV-STAT-POST-ERROR-BIT-COUNT` and :ref:`DTV-STAT-POST-TOTAL-BIT-COUNT`)
+  - Those counters measure the number of bits and bit errors errors after
+    the forward error correction (FEC) on the inner coding block
+    (after Viterbi, LDPC or other inner code).
+
+  - Due to its nature, those statistics depend on full coding lock
+    (e. g. after ``FE_HAS_SYNC`` or after ``FE_HAS_LOCK``,
+    see :c:type:`fe_status`).
+
+Bit counts pre-FEC (:ref:`DTV-STAT-PRE-ERROR-BIT-COUNT` and :ref:`DTV-STAT-PRE-TOTAL-BIT-COUNT`)
+  - Those counters measure the number of bits and bit errors errors before
+    the forward error correction (FEC) on the inner coding block
+    (before Viterbi, LDPC or other inner code).
+
+  - Not all frontends provide this kind of statistics.
+
+  - Due to its nature, those statistics depend on inner coding lock (e. g.
+    after ``FE_HAS_VITERBI``, see :c:type:`fe_status`).
+
+Block counts (:ref:`DTV-STAT-ERROR-BLOCK-COUNT` and :ref:`DTV-STAT-TOTAL-BLOCK-COUNT`)
+  - Those counters measure the number of blocks and block errors errors after
+    the forward error correction (FEC) on the inner coding block
+    (before Viterbi, LDPC or other inner code).
+
+  - Due to its nature, those statistics depend on full coding lock
+    (e. g. after ``FE_HAS_SYNC`` or after
+    ``FE_HAS_LOCK``, see :c:type:`fe_status`).
+
+.. note:: All counters should be monotonically increased as they're
+   collected from the hardware.
+
+A typical example of the logic that handle status and statistics is::
+
+	static int foo_get_status_and_stats(struct dvb_frontend *fe)
+	{
+		struct foo_state *state = fe->demodulator_priv;
+		struct dtv_frontend_properties *c = &fe->dtv_property_cache;
+
+		int rc;
+		enum fe_status *status;
+
+		/* Both status and strength are always available */
+		rc = foo_read_status(fe, &status);
+		if (rc < 0)
+			return rc;
+
+		rc = foo_read_strength(fe);
+		if (rc < 0)
+			return rc;
+
+		/* Check if CNR is available */
+		if (!(fe->status & FE_HAS_CARRIER))
+			return 0;
+
+		rc = foo_read_cnr(fe);
+		if (rc < 0)
+			return rc;
+
+		/* Check if pre-BER stats are available */
+		if (!(fe->status & FE_HAS_VITERBI))
+			return 0;
+
+		rc = foo_get_pre_ber(fe);
+		if (rc < 0)
+			return rc;
+
+		/* Check if post-BER stats are available */
+		if (!(fe->status & FE_HAS_SYNC))
+			return 0;
+
+		rc = foo_get_post_ber(fe);
+		if (rc < 0)
+			return rc;
+	}
+
+	static const struct dvb_frontend_ops ops = {
+		/* ... */
+		.read_status = foo_get_status_and_stats,
+	};
+
+Statistics collection
+^^^^^^^^^^^^^^^^^^^^^
+
+On almost all frontend hardware, the bit and byte counts are stored by
+the hardware after a certain amount of time or after the total bit/block
+counter reaches a certain value (usually programmable), for example, on
+every 1000 ms or after receiving 1,000,000 bits.
+
+So, if you read the registers too soon, you'll end by reading the same
+value as in the previous reading, causing the monotonic value to be
+incremented too often.
+
+Drivers should take the responsibility to avoid too often reads. That
+can be done using two approaches:
+
+if the driver have a bit that indicates when a collected data is ready
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+Driver should check such bit before making the statistics available.
+
+An example of such behavior can be found at this code snippet (adapted
+from mb86a20s driver's logic)::
+
+	static int foo_get_pre_ber(struct dvb_frontend *fe)
+	{
+		struct foo_state *state = fe->demodulator_priv;
+		struct dtv_frontend_properties *c = &fe->dtv_property_cache;
+		int rc, bit_error;
+
+		/* Check if the BER measures are already available */
+		rc = foo_read_u8(state, 0x54);
+		if (rc < 0)
+			return rc;
+
+		if (!rc)
+			return 0;
+
+		/* Read Bit Error Count */
+		bit_error = foo_read_u32(state, 0x55);
+		if (bit_error < 0)
+			return bit_error;
+
+		/* Read Total Bit Count */
+		rc = foo_read_u32(state, 0x51);
+		if (rc < 0)
+			return rc;
+
+		c->pre_bit_error.stat[0].scale = FE_SCALE_COUNTER;
+		c->pre_bit_error.stat[0].uvalue += bit_error;
+		c->pre_bit_count.stat[0].scale = FE_SCALE_COUNTER;
+		c->pre_bit_count.stat[0].uvalue += rc;
+
+		return 0;
+	}
+
+If the driver doesn't provide a statistics available check bit
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+A few devices, however, may not provide a way to check if the stats are
+available (or the way to check it is unknown). They may not even provide
+a way to directly read the total number of bits or blocks.
+
+On those devices, the driver need to ensure that it won't be reading from
+the register too often and/or estimate the total number of bits/blocks.
+
+On such drivers, a typical routine to get statistics would be like
+(adapted from dib8000 driver's logic)::
+
+	struct foo_state {
+		/* ... */
+
+		unsigned long per_jiffies_stats;
+	}
+
+	static int foo_get_pre_ber(struct dvb_frontend *fe)
+	{
+		struct foo_state *state = fe->demodulator_priv;
+		struct dtv_frontend_properties *c = &fe->dtv_property_cache;
+		int rc, bit_error;
+		u64 bits;
+
+		/* Check if time for stats was elapsed */
+		if (!time_after(jiffies, state->per_jiffies_stats))
+			return 0;
+
+		/* Next stat should be collected in 1000 ms */
+		state->per_jiffies_stats = jiffies + msecs_to_jiffies(1000);
+
+		/* Read Bit Error Count */
+		bit_error = foo_read_u32(state, 0x55);
+		if (bit_error < 0)
+			return bit_error;
+
+		/*
+		 * On this particular frontend, there's no register that
+		 * would provide the number of bits per 1000ms sample. So,
+		 * some function would calculate it based on DTV properties
+		 */
+		bits = get_number_of_bits_per_1000ms(fe);
+
+		c->pre_bit_error.stat[0].scale = FE_SCALE_COUNTER;
+		c->pre_bit_error.stat[0].uvalue += bit_error;
+		c->pre_bit_count.stat[0].scale = FE_SCALE_COUNTER;
+		c->pre_bit_count.stat[0].uvalue += bits;
+
+		return 0;
+	}
+
+Please notice that, on both cases, we're getting the statistics using the
+:c:type:`dvb_frontend_ops` ``.read_status`` callback. The rationale is that
+the frontend core will automatically call this function periodically
+(usually, 3 times per second, when the frontend is locked).
+
+That warrants that we won't miss to collect a counter and increment the
+monotonic stats at the right time.
+
+Digital TV Frontend functions and types
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/media/dvb_frontend.h
diff --git a/Documentation/driver-api/media/dtv-net.rst b/Documentation/driver-api/media/dtv-net.rst
new file mode 100644
index 000000000000..deb6bffe96bb
--- /dev/null
+++ b/Documentation/driver-api/media/dtv-net.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Digital TV Network kABI
+-----------------------
+
+.. kernel-doc:: include/media/dvb_net.h
diff --git a/Documentation/driver-api/media/index.rst b/Documentation/driver-api/media/index.rst
new file mode 100644
index 000000000000..d2842f300bbd
--- /dev/null
+++ b/Documentation/driver-api/media/index.rst
@@ -0,0 +1,38 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+===================================
+Media subsystem kernel internal API
+===================================
+
+**Copyright** |copy| 2009-2016 : LinuxTV Developers
+
+This documentation is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 2 of the License, or (at your option) any
+later version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+more details.
+
+For more details see the file COPYING in the source distribution of Linux.
+
+.. only:: html
+
+   .. class:: toc-title
+
+        Table of Contents
+
+.. toctree::
+    :maxdepth: 5
+    :numbered:
+
+    v4l2-core
+    dtv-core
+    rc-core
+    mc-core
+    cec-core
+    csi2
diff --git a/Documentation/driver-api/media/mc-core.rst b/Documentation/driver-api/media/mc-core.rst
new file mode 100644
index 000000000000..05bba0b61748
--- /dev/null
+++ b/Documentation/driver-api/media/mc-core.rst
@@ -0,0 +1,309 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Media Controller devices
+------------------------
+
+Media Controller
+~~~~~~~~~~~~~~~~
+
+The media controller userspace API is documented in
+:ref:`the Media Controller uAPI book <media_controller>`. This document focus
+on the kernel-side implementation of the media framework.
+
+Abstract media device model
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Discovering a device internal topology, and configuring it at runtime, is one
+of the goals of the media framework. To achieve this, hardware devices are
+modelled as an oriented graph of building blocks called entities connected
+through pads.
+
+An entity is a basic media hardware building block. It can correspond to
+a large variety of logical blocks such as physical hardware devices
+(CMOS sensor for instance), logical hardware devices (a building block
+in a System-on-Chip image processing pipeline), DMA channels or physical
+connectors.
+
+A pad is a connection endpoint through which an entity can interact with
+other entities. Data (not restricted to video) produced by an entity
+flows from the entity's output to one or more entity inputs. Pads should
+not be confused with physical pins at chip boundaries.
+
+A link is a point-to-point oriented connection between two pads, either
+on the same entity or on different entities. Data flows from a source
+pad to a sink pad.
+
+Media device
+^^^^^^^^^^^^
+
+A media device is represented by a struct :c:type:`media_device`
+instance, defined in ``include/media/media-device.h``.
+Allocation of the structure is handled by the media device driver, usually by
+embedding the :c:type:`media_device` instance in a larger driver-specific
+structure.
+
+Drivers register media device instances by calling
+:c:func:`__media_device_register()` via the macro ``media_device_register()``
+and unregistered by calling :c:func:`media_device_unregister()`.
+
+Entities
+^^^^^^^^
+
+Entities are represented by a struct :c:type:`media_entity`
+instance, defined in ``include/media/media-entity.h``. The structure is usually
+embedded into a higher-level structure, such as
+:c:type:`v4l2_subdev` or :c:type:`video_device`
+instances, although drivers can allocate entities directly.
+
+Drivers initialize entity pads by calling
+:c:func:`media_entity_pads_init()`.
+
+Drivers register entities with a media device by calling
+:c:func:`media_device_register_entity()`
+and unregistered by calling
+:c:func:`media_device_unregister_entity()`.
+
+Interfaces
+^^^^^^^^^^
+
+Interfaces are represented by a
+struct :c:type:`media_interface` instance, defined in
+``include/media/media-entity.h``. Currently, only one type of interface is
+defined: a device node. Such interfaces are represented by a
+struct :c:type:`media_intf_devnode`.
+
+Drivers initialize and create device node interfaces by calling
+:c:func:`media_devnode_create()`
+and remove them by calling:
+:c:func:`media_devnode_remove()`.
+
+Pads
+^^^^
+Pads are represented by a struct :c:type:`media_pad` instance,
+defined in ``include/media/media-entity.h``. Each entity stores its pads in
+a pads array managed by the entity driver. Drivers usually embed the array in
+a driver-specific structure.
+
+Pads are identified by their entity and their 0-based index in the pads
+array.
+
+Both information are stored in the struct :c:type:`media_pad`,
+making the struct :c:type:`media_pad` pointer the canonical way
+to store and pass link references.
+
+Pads have flags that describe the pad capabilities and state.
+
+``MEDIA_PAD_FL_SINK`` indicates that the pad supports sinking data.
+``MEDIA_PAD_FL_SOURCE`` indicates that the pad supports sourcing data.
+
+.. note::
+
+  One and only one of ``MEDIA_PAD_FL_SINK`` or ``MEDIA_PAD_FL_SOURCE`` must
+  be set for each pad.
+
+Links
+^^^^^
+
+Links are represented by a struct :c:type:`media_link` instance,
+defined in ``include/media/media-entity.h``. There are two types of links:
+
+**1. pad to pad links**:
+
+Associate two entities via their PADs. Each entity has a list that points
+to all links originating at or targeting any of its pads.
+A given link is thus stored twice, once in the source entity and once in
+the target entity.
+
+Drivers create pad to pad links by calling:
+:c:func:`media_create_pad_link()` and remove with
+:c:func:`media_entity_remove_links()`.
+
+**2. interface to entity links**:
+
+Associate one interface to a Link.
+
+Drivers create interface to entity links by calling:
+:c:func:`media_create_intf_link()` and remove with
+:c:func:`media_remove_intf_links()`.
+
+.. note::
+
+   Links can only be created after having both ends already created.
+
+Links have flags that describe the link capabilities and state. The
+valid values are described at :c:func:`media_create_pad_link()` and
+:c:func:`media_create_intf_link()`.
+
+Graph traversal
+^^^^^^^^^^^^^^^
+
+The media framework provides APIs to iterate over entities in a graph.
+
+To iterate over all entities belonging to a media device, drivers can use
+the media_device_for_each_entity macro, defined in
+``include/media/media-device.h``.
+
+..  code-block:: c
+
+    struct media_entity *entity;
+
+    media_device_for_each_entity(entity, mdev) {
+    // entity will point to each entity in turn
+    ...
+    }
+
+Drivers might also need to iterate over all entities in a graph that can be
+reached only through enabled links starting at a given entity. The media
+framework provides a depth-first graph traversal API for that purpose.
+
+.. note::
+
+   Graphs with cycles (whether directed or undirected) are **NOT**
+   supported by the graph traversal API. To prevent infinite loops, the graph
+   traversal code limits the maximum depth to ``MEDIA_ENTITY_ENUM_MAX_DEPTH``,
+   currently defined as 16.
+
+Drivers initiate a graph traversal by calling
+:c:func:`media_graph_walk_start()`
+
+The graph structure, provided by the caller, is initialized to start graph
+traversal at the given entity.
+
+Drivers can then retrieve the next entity by calling
+:c:func:`media_graph_walk_next()`
+
+When the graph traversal is complete the function will return ``NULL``.
+
+Graph traversal can be interrupted at any moment. No cleanup function call
+is required and the graph structure can be freed normally.
+
+Helper functions can be used to find a link between two given pads, or a pad
+connected to another pad through an enabled link
+:c:func:`media_entity_find_link()` and
+:c:func:`media_entity_remote_pad()`.
+
+Use count and power handling
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Due to the wide differences between drivers regarding power management
+needs, the media controller does not implement power management. However,
+the struct :c:type:`media_entity` includes a ``use_count``
+field that media drivers
+can use to track the number of users of every entity for power management
+needs.
+
+The :c:type:`media_entity<media_entity>`.\ ``use_count`` field is owned by
+media drivers and must not be
+touched by entity drivers. Access to the field must be protected by the
+:c:type:`media_device`.\ ``graph_mutex`` lock.
+
+Links setup
+^^^^^^^^^^^
+
+Link properties can be modified at runtime by calling
+:c:func:`media_entity_setup_link()`.
+
+Pipelines and media streams
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When starting streaming, drivers must notify all entities in the pipeline to
+prevent link states from being modified during streaming by calling
+:c:func:`media_pipeline_start()`.
+
+The function will mark all entities connected to the given entity through
+enabled links, either directly or indirectly, as streaming.
+
+The struct :c:type:`media_pipeline` instance pointed to by
+the pipe argument will be stored in every entity in the pipeline.
+Drivers should embed the struct :c:type:`media_pipeline`
+in higher-level pipeline structures and can then access the
+pipeline through the struct :c:type:`media_entity`
+pipe field.
+
+Calls to :c:func:`media_pipeline_start()` can be nested.
+The pipeline pointer must be identical for all nested calls to the function.
+
+:c:func:`media_pipeline_start()` may return an error. In that case,
+it will clean up any of the changes it did by itself.
+
+When stopping the stream, drivers must notify the entities with
+:c:func:`media_pipeline_stop()`.
+
+If multiple calls to :c:func:`media_pipeline_start()` have been
+made the same number of :c:func:`media_pipeline_stop()` calls
+are required to stop streaming.
+The :c:type:`media_entity`.\ ``pipe`` field is reset to ``NULL`` on the last
+nested stop call.
+
+Link configuration will fail with ``-EBUSY`` by default if either end of the
+link is a streaming entity. Links that can be modified while streaming must
+be marked with the ``MEDIA_LNK_FL_DYNAMIC`` flag.
+
+If other operations need to be disallowed on streaming entities (such as
+changing entities configuration parameters) drivers can explicitly check the
+media_entity stream_count field to find out if an entity is streaming. This
+operation must be done with the media_device graph_mutex held.
+
+Link validation
+^^^^^^^^^^^^^^^
+
+Link validation is performed by :c:func:`media_pipeline_start()`
+for any entity which has sink pads in the pipeline. The
+:c:type:`media_entity`.\ ``link_validate()`` callback is used for that
+purpose. In ``link_validate()`` callback, entity driver should check
+that the properties of the source pad of the connected entity and its own
+sink pad match. It is up to the type of the entity (and in the end, the
+properties of the hardware) what matching actually means.
+
+Subsystems should facilitate link validation by providing subsystem specific
+helper functions to provide easy access for commonly needed information, and
+in the end provide a way to use driver-specific callbacks.
+
+Media Controller Device Allocator API
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When the media device belongs to more than one driver, the shared media
+device is allocated with the shared struct device as the key for look ups.
+
+The shared media device should stay in registered state until the last
+driver unregisters it. In addition, the media device should be released when
+all the references are released. Each driver gets a reference to the media
+device during probe, when it allocates the media device. If media device is
+already allocated, the allocate API bumps up the refcount and returns the
+existing media device. The driver puts the reference back in its disconnect
+routine when it calls :c:func:`media_device_delete()`.
+
+The media device is unregistered and cleaned up from the kref put handler to
+ensure that the media device stays in registered state until the last driver
+unregisters the media device.
+
+**Driver Usage**
+
+Drivers should use the appropriate media-core routines to manage the shared
+media device life-time handling the two states:
+1. allocate -> register -> delete
+2. get reference to already registered device -> delete
+
+call :c:func:`media_device_delete()` routine to make sure the shared media
+device delete is handled correctly.
+
+**driver probe:**
+Call :c:func:`media_device_usb_allocate()` to allocate or get a reference
+Call :c:func:`media_device_register()`, if media devnode isn't registered
+
+**driver disconnect:**
+Call :c:func:`media_device_delete()` to free the media_device. Freeing is
+handled by the kref put handler.
+
+API Definitions
+^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/media-device.h
+
+.. kernel-doc:: include/media/media-devnode.h
+
+.. kernel-doc:: include/media/media-entity.h
+
+.. kernel-doc:: include/media/media-request.h
+
+.. kernel-doc:: include/media/media-dev-allocator.h
diff --git a/Documentation/driver-api/media/rc-core.rst b/Documentation/driver-api/media/rc-core.rst
new file mode 100644
index 000000000000..53f5e643b6e9
--- /dev/null
+++ b/Documentation/driver-api/media/rc-core.rst
@@ -0,0 +1,88 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Remote Controller devices
+-------------------------
+
+Remote Controller core
+~~~~~~~~~~~~~~~~~~~~~~
+
+The remote controller core implements infrastructure to receive and send
+remote controller keyboard keystrokes and mouse events.
+
+Every time a key is pressed on a remote controller, a scan code is produced.
+Also, on most hardware, keeping a key pressed for more than a few dozens of
+milliseconds produce a repeat key event. That's somewhat similar to what
+a normal keyboard or mouse is handled internally on Linux\ [#f1]_. So, the
+remote controller core is implemented on the top of the linux input/evdev
+interface.
+
+.. [#f1]
+
+   The main difference is that, on keyboard events, the keyboard controller
+   produces one event for a key press and another one for key release. On
+   infrared-based remote controllers, there's no key release event. Instead,
+   an extra code is produced to indicate key repeats.
+
+However, most of the remote controllers use infrared (IR) to transmit signals.
+As there are several protocols used to modulate infrared signals, one
+important part of the core is dedicated to adjust the driver and the core
+system to support the infrared protocol used by the emitter.
+
+The infrared transmission is done by blinking a infrared emitter using a
+carrier. The carrier can be switched on or off by the IR transmitter
+hardware. When the carrier is switched on, it is called *PULSE*.
+When the carrier is switched off, it is called *SPACE*.
+
+In other words, a typical IR transmission can be viewed as a sequence of
+*PULSE* and *SPACE* events, each with a given duration.
+
+The carrier parameters (frequency, duty cycle) and the intervals for
+*PULSE* and *SPACE* events depend on the protocol.
+For example, the NEC protocol uses a carrier of 38kHz, and transmissions
+start with a 9ms *PULSE* and a 4.5ms SPACE. It then transmits 16 bits of
+scan code, being 8 bits for address (usually it is a fixed number for a
+given remote controller), followed by 8 bits of code. A bit "1" is modulated
+with 560µs *PULSE* followed by 1690µs *SPACE* and a bit "0"  is modulated
+with 560µs *PULSE* followed by 560µs *SPACE*.
+
+At receiver, a simple low-pass filter can be used to convert the received
+signal in a sequence of *PULSE/SPACE* events, filtering out the carrier
+frequency. Due to that, the receiver doesn't care about the carrier's
+actual frequency parameters: all it has to do is to measure the amount
+of time it receives *PULSE/SPACE* events.
+So, a simple IR receiver hardware will just provide a sequence of timings
+for those events to the Kernel. The drivers for hardware with such kind of
+receivers are identified by  ``RC_DRIVER_IR_RAW``, as defined by
+:c:type:`rc_driver_type`\ [#f2]_. Other hardware come with a
+microcontroller that decode the *PULSE/SPACE* sequence and return scan
+codes to the Kernel. Such kind of receivers are identified
+by ``RC_DRIVER_SCANCODE``.
+
+.. [#f2]
+
+   The RC core also supports devices that have just IR emitters,
+   without any receivers. Right now, all such devices work only in
+   raw TX mode. Such kind of hardware is identified as
+   ``RC_DRIVER_IR_RAW_TX``.
+
+When the RC core receives events produced by ``RC_DRIVER_IR_RAW`` IR
+receivers, it needs to decode the IR protocol, in order to obtain the
+corresponding scan code. The protocols supported by the RC core are
+defined at enum :c:type:`rc_proto`.
+
+When the RC code receives a scan code (either directly, by a driver
+of the type ``RC_DRIVER_SCANCODE``, or via its IR decoders), it needs
+to convert into a Linux input event code. This is done via a mapping
+table.
+
+The Kernel has support for mapping tables available on most media
+devices. It also supports loading a table in runtime, via some
+sysfs nodes. See the :ref:`RC userspace API <Remote_controllers_Intro>`
+for more details.
+
+Remote controller data structures and functions
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/rc-core.h
+
+.. kernel-doc:: include/media/rc-map.h
diff --git a/Documentation/driver-api/media/v4l2-async.rst b/Documentation/driver-api/media/v4l2-async.rst
new file mode 100644
index 000000000000..3422330b3b1f
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-async.rst
@@ -0,0 +1,5 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 async kAPI
+^^^^^^^^^^^^^^^
+.. kernel-doc:: include/media/v4l2-async.h
diff --git a/Documentation/driver-api/media/v4l2-clocks.rst b/Documentation/driver-api/media/v4l2-clocks.rst
new file mode 100644
index 000000000000..5c22eecab7ba
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-clocks.rst
@@ -0,0 +1,31 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 clocks
+-----------
+
+.. attention::
+
+	This is a temporary API and it shall be replaced by the generic
+	clock API, when the latter becomes widely available.
+
+Many subdevices, like camera sensors, TV decoders and encoders, need a clock
+signal to be supplied by the system. Often this clock is supplied by the
+respective bridge device. The Linux kernel provides a Common Clock Framework for
+this purpose. However, it is not (yet) available on all architectures. Besides,
+the nature of the multi-functional (clock, data + synchronisation, I2C control)
+connection of subdevices to the system might impose special requirements on the
+clock API usage. E.g. V4L2 has to support clock provider driver unregistration
+while a subdevice driver is holding a reference to the clock. For these reasons
+a V4L2 clock helper API has been developed and is provided to bridge and
+subdevice drivers.
+
+The API consists of two parts: two functions to register and unregister a V4L2
+clock source: v4l2_clk_register() and v4l2_clk_unregister() and calls to control
+a clock object, similar to the respective generic clock API calls:
+v4l2_clk_get(), v4l2_clk_put(), v4l2_clk_enable(), v4l2_clk_disable(),
+v4l2_clk_get_rate(), and v4l2_clk_set_rate(). Clock suppliers have to provide
+clock operations that will be called when clock users invoke respective API
+methods.
+
+It is expected that once the CCF becomes available on all relevant
+architectures this API will be removed.
diff --git a/Documentation/driver-api/media/v4l2-common.rst b/Documentation/driver-api/media/v4l2-common.rst
new file mode 100644
index 000000000000..b1e70eb56aa4
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-common.rst
@@ -0,0 +1,8 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 common functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-common.h
+
+.. kernel-doc:: include/media/v4l2-ioctl.h
diff --git a/Documentation/driver-api/media/v4l2-controls.rst b/Documentation/driver-api/media/v4l2-controls.rst
new file mode 100644
index 000000000000..5129019afb49
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-controls.rst
@@ -0,0 +1,823 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 Controls
+=============
+
+Introduction
+------------
+
+The V4L2 control API seems simple enough, but quickly becomes very hard to
+implement correctly in drivers. But much of the code needed to handle controls
+is actually not driver specific and can be moved to the V4L core framework.
+
+After all, the only part that a driver developer is interested in is:
+
+1) How do I add a control?
+2) How do I set the control's value? (i.e. s_ctrl)
+
+And occasionally:
+
+3) How do I get the control's value? (i.e. g_volatile_ctrl)
+4) How do I validate the user's proposed control value? (i.e. try_ctrl)
+
+All the rest is something that can be done centrally.
+
+The control framework was created in order to implement all the rules of the
+V4L2 specification with respect to controls in a central place. And to make
+life as easy as possible for the driver developer.
+
+Note that the control framework relies on the presence of a struct
+:c:type:`v4l2_device` for V4L2 drivers and struct :c:type:`v4l2_subdev` for
+sub-device drivers.
+
+
+Objects in the framework
+------------------------
+
+There are two main objects:
+
+The :c:type:`v4l2_ctrl` object describes the control properties and keeps
+track of the control's value (both the current value and the proposed new
+value).
+
+:c:type:`v4l2_ctrl_handler` is the object that keeps track of controls. It
+maintains a list of v4l2_ctrl objects that it owns and another list of
+references to controls, possibly to controls owned by other handlers.
+
+
+Basic usage for V4L2 and sub-device drivers
+-------------------------------------------
+
+1) Prepare the driver:
+
+.. code-block:: c
+
+	#include <media/v4l2-ctrls.h>
+
+1.1) Add the handler to your driver's top-level struct:
+
+For V4L2 drivers:
+
+.. code-block:: c
+
+	struct foo_dev {
+		...
+		struct v4l2_device v4l2_dev;
+		...
+		struct v4l2_ctrl_handler ctrl_handler;
+		...
+	};
+
+For sub-device drivers:
+
+.. code-block:: c
+
+	struct foo_dev {
+		...
+		struct v4l2_subdev sd;
+		...
+		struct v4l2_ctrl_handler ctrl_handler;
+		...
+	};
+
+1.2) Initialize the handler:
+
+.. code-block:: c
+
+	v4l2_ctrl_handler_init(&foo->ctrl_handler, nr_of_controls);
+
+The second argument is a hint telling the function how many controls this
+handler is expected to handle. It will allocate a hashtable based on this
+information. It is a hint only.
+
+1.3) Hook the control handler into the driver:
+
+For V4L2 drivers:
+
+.. code-block:: c
+
+	foo->v4l2_dev.ctrl_handler = &foo->ctrl_handler;
+
+For sub-device drivers:
+
+.. code-block:: c
+
+	foo->sd.ctrl_handler = &foo->ctrl_handler;
+
+1.4) Clean up the handler at the end:
+
+.. code-block:: c
+
+	v4l2_ctrl_handler_free(&foo->ctrl_handler);
+
+
+2) Add controls:
+
+You add non-menu controls by calling :c:func:`v4l2_ctrl_new_std`:
+
+.. code-block:: c
+
+	struct v4l2_ctrl *v4l2_ctrl_new_std(struct v4l2_ctrl_handler *hdl,
+			const struct v4l2_ctrl_ops *ops,
+			u32 id, s32 min, s32 max, u32 step, s32 def);
+
+Menu and integer menu controls are added by calling
+:c:func:`v4l2_ctrl_new_std_menu`:
+
+.. code-block:: c
+
+	struct v4l2_ctrl *v4l2_ctrl_new_std_menu(struct v4l2_ctrl_handler *hdl,
+			const struct v4l2_ctrl_ops *ops,
+			u32 id, s32 max, s32 skip_mask, s32 def);
+
+Menu controls with a driver specific menu are added by calling
+:c:func:`v4l2_ctrl_new_std_menu_items`:
+
+.. code-block:: c
+
+       struct v4l2_ctrl *v4l2_ctrl_new_std_menu_items(
+                       struct v4l2_ctrl_handler *hdl,
+                       const struct v4l2_ctrl_ops *ops, u32 id, s32 max,
+                       s32 skip_mask, s32 def, const char * const *qmenu);
+
+Standard compound controls can be added by calling
+:c:func:`v4l2_ctrl_new_std_compound`:
+
+.. code-block:: c
+
+       struct v4l2_ctrl *v4l2_ctrl_new_std_compound(struct v4l2_ctrl_handler *hdl,
+                       const struct v4l2_ctrl_ops *ops, u32 id,
+                       const union v4l2_ctrl_ptr p_def);
+
+Integer menu controls with a driver specific menu can be added by calling
+:c:func:`v4l2_ctrl_new_int_menu`:
+
+.. code-block:: c
+
+	struct v4l2_ctrl *v4l2_ctrl_new_int_menu(struct v4l2_ctrl_handler *hdl,
+			const struct v4l2_ctrl_ops *ops,
+			u32 id, s32 max, s32 def, const s64 *qmenu_int);
+
+These functions are typically called right after the
+:c:func:`v4l2_ctrl_handler_init`:
+
+.. code-block:: c
+
+	static const s64 exp_bias_qmenu[] = {
+	       -2, -1, 0, 1, 2
+	};
+	static const char * const test_pattern[] = {
+		"Disabled",
+		"Vertical Bars",
+		"Solid Black",
+		"Solid White",
+	};
+
+	v4l2_ctrl_handler_init(&foo->ctrl_handler, nr_of_controls);
+	v4l2_ctrl_new_std(&foo->ctrl_handler, &foo_ctrl_ops,
+			V4L2_CID_BRIGHTNESS, 0, 255, 1, 128);
+	v4l2_ctrl_new_std(&foo->ctrl_handler, &foo_ctrl_ops,
+			V4L2_CID_CONTRAST, 0, 255, 1, 128);
+	v4l2_ctrl_new_std_menu(&foo->ctrl_handler, &foo_ctrl_ops,
+			V4L2_CID_POWER_LINE_FREQUENCY,
+			V4L2_CID_POWER_LINE_FREQUENCY_60HZ, 0,
+			V4L2_CID_POWER_LINE_FREQUENCY_DISABLED);
+	v4l2_ctrl_new_int_menu(&foo->ctrl_handler, &foo_ctrl_ops,
+			V4L2_CID_EXPOSURE_BIAS,
+			ARRAY_SIZE(exp_bias_qmenu) - 1,
+			ARRAY_SIZE(exp_bias_qmenu) / 2 - 1,
+			exp_bias_qmenu);
+	v4l2_ctrl_new_std_menu_items(&foo->ctrl_handler, &foo_ctrl_ops,
+			V4L2_CID_TEST_PATTERN, ARRAY_SIZE(test_pattern) - 1, 0,
+			0, test_pattern);
+	...
+	if (foo->ctrl_handler.error) {
+		int err = foo->ctrl_handler.error;
+
+		v4l2_ctrl_handler_free(&foo->ctrl_handler);
+		return err;
+	}
+
+The :c:func:`v4l2_ctrl_new_std` function returns the v4l2_ctrl pointer to
+the new control, but if you do not need to access the pointer outside the
+control ops, then there is no need to store it.
+
+The :c:func:`v4l2_ctrl_new_std` function will fill in most fields based on
+the control ID except for the min, max, step and default values. These are
+passed in the last four arguments. These values are driver specific while
+control attributes like type, name, flags are all global. The control's
+current value will be set to the default value.
+
+The :c:func:`v4l2_ctrl_new_std_menu` function is very similar but it is
+used for menu controls. There is no min argument since that is always 0 for
+menu controls, and instead of a step there is a skip_mask argument: if bit
+X is 1, then menu item X is skipped.
+
+The :c:func:`v4l2_ctrl_new_int_menu` function creates a new standard
+integer menu control with driver-specific items in the menu. It differs
+from v4l2_ctrl_new_std_menu in that it doesn't have the mask argument and
+takes as the last argument an array of signed 64-bit integers that form an
+exact menu item list.
+
+The :c:func:`v4l2_ctrl_new_std_menu_items` function is very similar to
+v4l2_ctrl_new_std_menu but takes an extra parameter qmenu, which is the
+driver specific menu for an otherwise standard menu control. A good example
+for this control is the test pattern control for capture/display/sensors
+devices that have the capability to generate test patterns. These test
+patterns are hardware specific, so the contents of the menu will vary from
+device to device.
+
+Note that if something fails, the function will return NULL or an error and
+set ctrl_handler->error to the error code. If ctrl_handler->error was already
+set, then it will just return and do nothing. This is also true for
+v4l2_ctrl_handler_init if it cannot allocate the internal data structure.
+
+This makes it easy to init the handler and just add all controls and only check
+the error code at the end. Saves a lot of repetitive error checking.
+
+It is recommended to add controls in ascending control ID order: it will be
+a bit faster that way.
+
+3) Optionally force initial control setup:
+
+.. code-block:: c
+
+	v4l2_ctrl_handler_setup(&foo->ctrl_handler);
+
+This will call s_ctrl for all controls unconditionally. Effectively this
+initializes the hardware to the default control values. It is recommended
+that you do this as this ensures that both the internal data structures and
+the hardware are in sync.
+
+4) Finally: implement the :c:type:`v4l2_ctrl_ops`
+
+.. code-block:: c
+
+	static const struct v4l2_ctrl_ops foo_ctrl_ops = {
+		.s_ctrl = foo_s_ctrl,
+	};
+
+Usually all you need is s_ctrl:
+
+.. code-block:: c
+
+	static int foo_s_ctrl(struct v4l2_ctrl *ctrl)
+	{
+		struct foo *state = container_of(ctrl->handler, struct foo, ctrl_handler);
+
+		switch (ctrl->id) {
+		case V4L2_CID_BRIGHTNESS:
+			write_reg(0x123, ctrl->val);
+			break;
+		case V4L2_CID_CONTRAST:
+			write_reg(0x456, ctrl->val);
+			break;
+		}
+		return 0;
+	}
+
+The control ops are called with the v4l2_ctrl pointer as argument.
+The new control value has already been validated, so all you need to do is
+to actually update the hardware registers.
+
+You're done! And this is sufficient for most of the drivers we have. No need
+to do any validation of control values, or implement QUERYCTRL, QUERY_EXT_CTRL
+and QUERYMENU. And G/S_CTRL as well as G/TRY/S_EXT_CTRLS are automatically supported.
+
+
+.. note::
+
+   The remainder sections deal with more advanced controls topics and scenarios.
+   In practice the basic usage as described above is sufficient for most drivers.
+
+
+Inheriting Sub-device Controls
+------------------------------
+
+When a sub-device is registered with a V4L2 driver by calling
+v4l2_device_register_subdev() and the ctrl_handler fields of both v4l2_subdev
+and v4l2_device are set, then the controls of the subdev will become
+automatically available in the V4L2 driver as well. If the subdev driver
+contains controls that already exist in the V4L2 driver, then those will be
+skipped (so a V4L2 driver can always override a subdev control).
+
+What happens here is that v4l2_device_register_subdev() calls
+v4l2_ctrl_add_handler() adding the controls of the subdev to the controls
+of v4l2_device.
+
+
+Accessing Control Values
+------------------------
+
+The following union is used inside the control framework to access control
+values:
+
+.. code-block:: c
+
+	union v4l2_ctrl_ptr {
+		s32 *p_s32;
+		s64 *p_s64;
+		char *p_char;
+		void *p;
+	};
+
+The v4l2_ctrl struct contains these fields that can be used to access both
+current and new values:
+
+.. code-block:: c
+
+	s32 val;
+	struct {
+		s32 val;
+	} cur;
+
+
+	union v4l2_ctrl_ptr p_new;
+	union v4l2_ctrl_ptr p_cur;
+
+If the control has a simple s32 type type, then:
+
+.. code-block:: c
+
+	&ctrl->val == ctrl->p_new.p_s32
+	&ctrl->cur.val == ctrl->p_cur.p_s32
+
+For all other types use ctrl->p_cur.p<something>. Basically the val
+and cur.val fields can be considered an alias since these are used so often.
+
+Within the control ops you can freely use these. The val and cur.val speak for
+themselves. The p_char pointers point to character buffers of length
+ctrl->maximum + 1, and are always 0-terminated.
+
+Unless the control is marked volatile the p_cur field points to the the
+current cached control value. When you create a new control this value is made
+identical to the default value. After calling v4l2_ctrl_handler_setup() this
+value is passed to the hardware. It is generally a good idea to call this
+function.
+
+Whenever a new value is set that new value is automatically cached. This means
+that most drivers do not need to implement the g_volatile_ctrl() op. The
+exception is for controls that return a volatile register such as a signal
+strength read-out that changes continuously. In that case you will need to
+implement g_volatile_ctrl like this:
+
+.. code-block:: c
+
+	static int foo_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
+	{
+		switch (ctrl->id) {
+		case V4L2_CID_BRIGHTNESS:
+			ctrl->val = read_reg(0x123);
+			break;
+		}
+	}
+
+Note that you use the 'new value' union as well in g_volatile_ctrl. In general
+controls that need to implement g_volatile_ctrl are read-only controls. If they
+are not, a V4L2_EVENT_CTRL_CH_VALUE will not be generated when the control
+changes.
+
+To mark a control as volatile you have to set V4L2_CTRL_FLAG_VOLATILE:
+
+.. code-block:: c
+
+	ctrl = v4l2_ctrl_new_std(&sd->ctrl_handler, ...);
+	if (ctrl)
+		ctrl->flags |= V4L2_CTRL_FLAG_VOLATILE;
+
+For try/s_ctrl the new values (i.e. as passed by the user) are filled in and
+you can modify them in try_ctrl or set them in s_ctrl. The 'cur' union
+contains the current value, which you can use (but not change!) as well.
+
+If s_ctrl returns 0 (OK), then the control framework will copy the new final
+values to the 'cur' union.
+
+While in g_volatile/s/try_ctrl you can access the value of all controls owned
+by the same handler since the handler's lock is held. If you need to access
+the value of controls owned by other handlers, then you have to be very careful
+not to introduce deadlocks.
+
+Outside of the control ops you have to go through to helper functions to get
+or set a single control value safely in your driver:
+
+.. code-block:: c
+
+	s32 v4l2_ctrl_g_ctrl(struct v4l2_ctrl *ctrl);
+	int v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val);
+
+These functions go through the control framework just as VIDIOC_G/S_CTRL ioctls
+do. Don't use these inside the control ops g_volatile/s/try_ctrl, though, that
+will result in a deadlock since these helpers lock the handler as well.
+
+You can also take the handler lock yourself:
+
+.. code-block:: c
+
+	mutex_lock(&state->ctrl_handler.lock);
+	pr_info("String value is '%s'\n", ctrl1->p_cur.p_char);
+	pr_info("Integer value is '%s'\n", ctrl2->cur.val);
+	mutex_unlock(&state->ctrl_handler.lock);
+
+
+Menu Controls
+-------------
+
+The v4l2_ctrl struct contains this union:
+
+.. code-block:: c
+
+	union {
+		u32 step;
+		u32 menu_skip_mask;
+	};
+
+For menu controls menu_skip_mask is used. What it does is that it allows you
+to easily exclude certain menu items. This is used in the VIDIOC_QUERYMENU
+implementation where you can return -EINVAL if a certain menu item is not
+present. Note that VIDIOC_QUERYCTRL always returns a step value of 1 for
+menu controls.
+
+A good example is the MPEG Audio Layer II Bitrate menu control where the
+menu is a list of standardized possible bitrates. But in practice hardware
+implementations will only support a subset of those. By setting the skip
+mask you can tell the framework which menu items should be skipped. Setting
+it to 0 means that all menu items are supported.
+
+You set this mask either through the v4l2_ctrl_config struct for a custom
+control, or by calling v4l2_ctrl_new_std_menu().
+
+
+Custom Controls
+---------------
+
+Driver specific controls can be created using v4l2_ctrl_new_custom():
+
+.. code-block:: c
+
+	static const struct v4l2_ctrl_config ctrl_filter = {
+		.ops = &ctrl_custom_ops,
+		.id = V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER,
+		.name = "Spatial Filter",
+		.type = V4L2_CTRL_TYPE_INTEGER,
+		.flags = V4L2_CTRL_FLAG_SLIDER,
+		.max = 15,
+		.step = 1,
+	};
+
+	ctrl = v4l2_ctrl_new_custom(&foo->ctrl_handler, &ctrl_filter, NULL);
+
+The last argument is the priv pointer which can be set to driver-specific
+private data.
+
+The v4l2_ctrl_config struct also has a field to set the is_private flag.
+
+If the name field is not set, then the framework will assume this is a standard
+control and will fill in the name, type and flags fields accordingly.
+
+
+Active and Grabbed Controls
+---------------------------
+
+If you get more complex relationships between controls, then you may have to
+activate and deactivate controls. For example, if the Chroma AGC control is
+on, then the Chroma Gain control is inactive. That is, you may set it, but
+the value will not be used by the hardware as long as the automatic gain
+control is on. Typically user interfaces can disable such input fields.
+
+You can set the 'active' status using v4l2_ctrl_activate(). By default all
+controls are active. Note that the framework does not check for this flag.
+It is meant purely for GUIs. The function is typically called from within
+s_ctrl.
+
+The other flag is the 'grabbed' flag. A grabbed control means that you cannot
+change it because it is in use by some resource. Typical examples are MPEG
+bitrate controls that cannot be changed while capturing is in progress.
+
+If a control is set to 'grabbed' using v4l2_ctrl_grab(), then the framework
+will return -EBUSY if an attempt is made to set this control. The
+v4l2_ctrl_grab() function is typically called from the driver when it
+starts or stops streaming.
+
+
+Control Clusters
+----------------
+
+By default all controls are independent from the others. But in more
+complex scenarios you can get dependencies from one control to another.
+In that case you need to 'cluster' them:
+
+.. code-block:: c
+
+	struct foo {
+		struct v4l2_ctrl_handler ctrl_handler;
+	#define AUDIO_CL_VOLUME (0)
+	#define AUDIO_CL_MUTE   (1)
+		struct v4l2_ctrl *audio_cluster[2];
+		...
+	};
+
+	state->audio_cluster[AUDIO_CL_VOLUME] =
+		v4l2_ctrl_new_std(&state->ctrl_handler, ...);
+	state->audio_cluster[AUDIO_CL_MUTE] =
+		v4l2_ctrl_new_std(&state->ctrl_handler, ...);
+	v4l2_ctrl_cluster(ARRAY_SIZE(state->audio_cluster), state->audio_cluster);
+
+From now on whenever one or more of the controls belonging to the same
+cluster is set (or 'gotten', or 'tried'), only the control ops of the first
+control ('volume' in this example) is called. You effectively create a new
+composite control. Similar to how a 'struct' works in C.
+
+So when s_ctrl is called with V4L2_CID_AUDIO_VOLUME as argument, you should set
+all two controls belonging to the audio_cluster:
+
+.. code-block:: c
+
+	static int foo_s_ctrl(struct v4l2_ctrl *ctrl)
+	{
+		struct foo *state = container_of(ctrl->handler, struct foo, ctrl_handler);
+
+		switch (ctrl->id) {
+		case V4L2_CID_AUDIO_VOLUME: {
+			struct v4l2_ctrl *mute = ctrl->cluster[AUDIO_CL_MUTE];
+
+			write_reg(0x123, mute->val ? 0 : ctrl->val);
+			break;
+		}
+		case V4L2_CID_CONTRAST:
+			write_reg(0x456, ctrl->val);
+			break;
+		}
+		return 0;
+	}
+
+In the example above the following are equivalent for the VOLUME case:
+
+.. code-block:: c
+
+	ctrl == ctrl->cluster[AUDIO_CL_VOLUME] == state->audio_cluster[AUDIO_CL_VOLUME]
+	ctrl->cluster[AUDIO_CL_MUTE] == state->audio_cluster[AUDIO_CL_MUTE]
+
+In practice using cluster arrays like this becomes very tiresome. So instead
+the following equivalent method is used:
+
+.. code-block:: c
+
+	struct {
+		/* audio cluster */
+		struct v4l2_ctrl *volume;
+		struct v4l2_ctrl *mute;
+	};
+
+The anonymous struct is used to clearly 'cluster' these two control pointers,
+but it serves no other purpose. The effect is the same as creating an
+array with two control pointers. So you can just do:
+
+.. code-block:: c
+
+	state->volume = v4l2_ctrl_new_std(&state->ctrl_handler, ...);
+	state->mute = v4l2_ctrl_new_std(&state->ctrl_handler, ...);
+	v4l2_ctrl_cluster(2, &state->volume);
+
+And in foo_s_ctrl you can use these pointers directly: state->mute->val.
+
+Note that controls in a cluster may be NULL. For example, if for some
+reason mute was never added (because the hardware doesn't support that
+particular feature), then mute will be NULL. So in that case we have a
+cluster of 2 controls, of which only 1 is actually instantiated. The
+only restriction is that the first control of the cluster must always be
+present, since that is the 'master' control of the cluster. The master
+control is the one that identifies the cluster and that provides the
+pointer to the v4l2_ctrl_ops struct that is used for that cluster.
+
+Obviously, all controls in the cluster array must be initialized to either
+a valid control or to NULL.
+
+In rare cases you might want to know which controls of a cluster actually
+were set explicitly by the user. For this you can check the 'is_new' flag of
+each control. For example, in the case of a volume/mute cluster the 'is_new'
+flag of the mute control would be set if the user called VIDIOC_S_CTRL for
+mute only. If the user would call VIDIOC_S_EXT_CTRLS for both mute and volume
+controls, then the 'is_new' flag would be 1 for both controls.
+
+The 'is_new' flag is always 1 when called from v4l2_ctrl_handler_setup().
+
+
+Handling autogain/gain-type Controls with Auto Clusters
+-------------------------------------------------------
+
+A common type of control cluster is one that handles 'auto-foo/foo'-type
+controls. Typical examples are autogain/gain, autoexposure/exposure,
+autowhitebalance/red balance/blue balance. In all cases you have one control
+that determines whether another control is handled automatically by the hardware,
+or whether it is under manual control from the user.
+
+If the cluster is in automatic mode, then the manual controls should be
+marked inactive and volatile. When the volatile controls are read the
+g_volatile_ctrl operation should return the value that the hardware's automatic
+mode set up automatically.
+
+If the cluster is put in manual mode, then the manual controls should become
+active again and the volatile flag is cleared (so g_volatile_ctrl is no longer
+called while in manual mode). In addition just before switching to manual mode
+the current values as determined by the auto mode are copied as the new manual
+values.
+
+Finally the V4L2_CTRL_FLAG_UPDATE should be set for the auto control since
+changing that control affects the control flags of the manual controls.
+
+In order to simplify this a special variation of v4l2_ctrl_cluster was
+introduced:
+
+.. code-block:: c
+
+	void v4l2_ctrl_auto_cluster(unsigned ncontrols, struct v4l2_ctrl **controls,
+				    u8 manual_val, bool set_volatile);
+
+The first two arguments are identical to v4l2_ctrl_cluster. The third argument
+tells the framework which value switches the cluster into manual mode. The
+last argument will optionally set V4L2_CTRL_FLAG_VOLATILE for the non-auto controls.
+If it is false, then the manual controls are never volatile. You would typically
+use that if the hardware does not give you the option to read back to values as
+determined by the auto mode (e.g. if autogain is on, the hardware doesn't allow
+you to obtain the current gain value).
+
+The first control of the cluster is assumed to be the 'auto' control.
+
+Using this function will ensure that you don't need to handle all the complex
+flag and volatile handling.
+
+
+VIDIOC_LOG_STATUS Support
+-------------------------
+
+This ioctl allow you to dump the current status of a driver to the kernel log.
+The v4l2_ctrl_handler_log_status(ctrl_handler, prefix) can be used to dump the
+value of the controls owned by the given handler to the log. You can supply a
+prefix as well. If the prefix didn't end with a space, then ': ' will be added
+for you.
+
+
+Different Handlers for Different Video Nodes
+--------------------------------------------
+
+Usually the V4L2 driver has just one control handler that is global for
+all video nodes. But you can also specify different control handlers for
+different video nodes. You can do that by manually setting the ctrl_handler
+field of struct video_device.
+
+That is no problem if there are no subdevs involved but if there are, then
+you need to block the automatic merging of subdev controls to the global
+control handler. You do that by simply setting the ctrl_handler field in
+struct v4l2_device to NULL. Now v4l2_device_register_subdev() will no longer
+merge subdev controls.
+
+After each subdev was added, you will then have to call v4l2_ctrl_add_handler
+manually to add the subdev's control handler (sd->ctrl_handler) to the desired
+control handler. This control handler may be specific to the video_device or
+for a subset of video_device's. For example: the radio device nodes only have
+audio controls, while the video and vbi device nodes share the same control
+handler for the audio and video controls.
+
+If you want to have one handler (e.g. for a radio device node) have a subset
+of another handler (e.g. for a video device node), then you should first add
+the controls to the first handler, add the other controls to the second
+handler and finally add the first handler to the second. For example:
+
+.. code-block:: c
+
+	v4l2_ctrl_new_std(&radio_ctrl_handler, &radio_ops, V4L2_CID_AUDIO_VOLUME, ...);
+	v4l2_ctrl_new_std(&radio_ctrl_handler, &radio_ops, V4L2_CID_AUDIO_MUTE, ...);
+	v4l2_ctrl_new_std(&video_ctrl_handler, &video_ops, V4L2_CID_BRIGHTNESS, ...);
+	v4l2_ctrl_new_std(&video_ctrl_handler, &video_ops, V4L2_CID_CONTRAST, ...);
+	v4l2_ctrl_add_handler(&video_ctrl_handler, &radio_ctrl_handler, NULL);
+
+The last argument to v4l2_ctrl_add_handler() is a filter function that allows
+you to filter which controls will be added. Set it to NULL if you want to add
+all controls.
+
+Or you can add specific controls to a handler:
+
+.. code-block:: c
+
+	volume = v4l2_ctrl_new_std(&video_ctrl_handler, &ops, V4L2_CID_AUDIO_VOLUME, ...);
+	v4l2_ctrl_new_std(&video_ctrl_handler, &ops, V4L2_CID_BRIGHTNESS, ...);
+	v4l2_ctrl_new_std(&video_ctrl_handler, &ops, V4L2_CID_CONTRAST, ...);
+
+What you should not do is make two identical controls for two handlers.
+For example:
+
+.. code-block:: c
+
+	v4l2_ctrl_new_std(&radio_ctrl_handler, &radio_ops, V4L2_CID_AUDIO_MUTE, ...);
+	v4l2_ctrl_new_std(&video_ctrl_handler, &video_ops, V4L2_CID_AUDIO_MUTE, ...);
+
+This would be bad since muting the radio would not change the video mute
+control. The rule is to have one control for each hardware 'knob' that you
+can twiddle.
+
+
+Finding Controls
+----------------
+
+Normally you have created the controls yourself and you can store the struct
+v4l2_ctrl pointer into your own struct.
+
+But sometimes you need to find a control from another handler that you do
+not own. For example, if you have to find a volume control from a subdev.
+
+You can do that by calling v4l2_ctrl_find:
+
+.. code-block:: c
+
+	struct v4l2_ctrl *volume;
+
+	volume = v4l2_ctrl_find(sd->ctrl_handler, V4L2_CID_AUDIO_VOLUME);
+
+Since v4l2_ctrl_find will lock the handler you have to be careful where you
+use it. For example, this is not a good idea:
+
+.. code-block:: c
+
+	struct v4l2_ctrl_handler ctrl_handler;
+
+	v4l2_ctrl_new_std(&ctrl_handler, &video_ops, V4L2_CID_BRIGHTNESS, ...);
+	v4l2_ctrl_new_std(&ctrl_handler, &video_ops, V4L2_CID_CONTRAST, ...);
+
+...and in video_ops.s_ctrl:
+
+.. code-block:: c
+
+	case V4L2_CID_BRIGHTNESS:
+		contrast = v4l2_find_ctrl(&ctrl_handler, V4L2_CID_CONTRAST);
+		...
+
+When s_ctrl is called by the framework the ctrl_handler.lock is already taken, so
+attempting to find another control from the same handler will deadlock.
+
+It is recommended not to use this function from inside the control ops.
+
+
+Preventing Controls inheritance
+-------------------------------
+
+When one control handler is added to another using v4l2_ctrl_add_handler, then
+by default all controls from one are merged to the other. But a subdev might
+have low-level controls that make sense for some advanced embedded system, but
+not when it is used in consumer-level hardware. In that case you want to keep
+those low-level controls local to the subdev. You can do this by simply
+setting the 'is_private' flag of the control to 1:
+
+.. code-block:: c
+
+	static const struct v4l2_ctrl_config ctrl_private = {
+		.ops = &ctrl_custom_ops,
+		.id = V4L2_CID_...,
+		.name = "Some Private Control",
+		.type = V4L2_CTRL_TYPE_INTEGER,
+		.max = 15,
+		.step = 1,
+		.is_private = 1,
+	};
+
+	ctrl = v4l2_ctrl_new_custom(&foo->ctrl_handler, &ctrl_private, NULL);
+
+These controls will now be skipped when v4l2_ctrl_add_handler is called.
+
+
+V4L2_CTRL_TYPE_CTRL_CLASS Controls
+----------------------------------
+
+Controls of this type can be used by GUIs to get the name of the control class.
+A fully featured GUI can make a dialog with multiple tabs with each tab
+containing the controls belonging to a particular control class. The name of
+each tab can be found by querying a special control with ID <control class | 1>.
+
+Drivers do not have to care about this. The framework will automatically add
+a control of this type whenever the first control belonging to a new control
+class is added.
+
+
+Adding Notify Callbacks
+-----------------------
+
+Sometimes the platform or bridge driver needs to be notified when a control
+from a sub-device driver changes. You can set a notify callback by calling
+this function:
+
+.. code-block:: c
+
+	void v4l2_ctrl_notify(struct v4l2_ctrl *ctrl,
+		void (*notify)(struct v4l2_ctrl *ctrl, void *priv), void *priv);
+
+Whenever the give control changes value the notify callback will be called
+with a pointer to the control and the priv pointer that was passed with
+v4l2_ctrl_notify. Note that the control's handler lock is held when the
+notify function is called.
+
+There can be only one notify function per control handler. Any attempt
+to set another notify function will cause a WARN_ON.
+
+v4l2_ctrl functions and data structures
+---------------------------------------
+
+.. kernel-doc:: include/media/v4l2-ctrls.h
diff --git a/Documentation/driver-api/media/v4l2-core.rst b/Documentation/driver-api/media/v4l2-core.rst
new file mode 100644
index 000000000000..0dcad7a23141
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-core.rst
@@ -0,0 +1,29 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Video4Linux devices
+-------------------
+
+.. toctree::
+    :maxdepth: 1
+
+    v4l2-intro
+    v4l2-dev
+    v4l2-device
+    v4l2-fh
+    v4l2-subdev
+    v4l2-event
+    v4l2-controls
+    v4l2-videobuf
+    v4l2-videobuf2
+    v4l2-clocks
+    v4l2-dv-timings
+    v4l2-flash-led-class
+    v4l2-mc
+    v4l2-mediabus
+    v4l2-mem2mem
+    v4l2-async
+    v4l2-fwnode
+    v4l2-rect
+    v4l2-tuner
+    v4l2-common
+    v4l2-tveeprom
diff --git a/Documentation/driver-api/media/v4l2-dev.rst b/Documentation/driver-api/media/v4l2-dev.rst
new file mode 100644
index 000000000000..63c064837c00
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-dev.rst
@@ -0,0 +1,375 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Video device' s internal representation
+=======================================
+
+The actual device nodes in the ``/dev`` directory are created using the
+:c:type:`video_device` struct (``v4l2-dev.h``). This struct can either be
+allocated dynamically or embedded in a larger struct.
+
+To allocate it dynamically use :c:func:`video_device_alloc`:
+
+.. code-block:: c
+
+	struct video_device *vdev = video_device_alloc();
+
+	if (vdev == NULL)
+		return -ENOMEM;
+
+	vdev->release = video_device_release;
+
+If you embed it in a larger struct, then you must set the ``release()``
+callback to your own function:
+
+.. code-block:: c
+
+	struct video_device *vdev = &my_vdev->vdev;
+
+	vdev->release = my_vdev_release;
+
+The ``release()`` callback must be set and it is called when the last user
+of the video device exits.
+
+The default :c:func:`video_device_release` callback currently
+just calls ``kfree`` to free the allocated memory.
+
+There is also a :c:func:`video_device_release_empty` function that does
+nothing (is empty) and should be used if the struct is embedded and there
+is nothing to do when it is released.
+
+You should also set these fields of :c:type:`video_device`:
+
+- :c:type:`video_device`->v4l2_dev: must be set to the :c:type:`v4l2_device`
+  parent device.
+
+- :c:type:`video_device`->name: set to something descriptive and unique.
+
+- :c:type:`video_device`->vfl_dir: set this to ``VFL_DIR_RX`` for capture
+  devices (``VFL_DIR_RX`` has value 0, so this is normally already the
+  default), set to ``VFL_DIR_TX`` for output devices and ``VFL_DIR_M2M`` for mem2mem (codec) devices.
+
+- :c:type:`video_device`->fops: set to the :c:type:`v4l2_file_operations`
+  struct.
+
+- :c:type:`video_device`->ioctl_ops: if you use the :c:type:`v4l2_ioctl_ops`
+  to simplify ioctl maintenance (highly recommended to use this and it might
+  become compulsory in the future!), then set this to your
+  :c:type:`v4l2_ioctl_ops` struct. The :c:type:`video_device`->vfl_type and
+  :c:type:`video_device`->vfl_dir fields are used to disable ops that do not
+  match the type/dir combination. E.g. VBI ops are disabled for non-VBI nodes,
+  and output ops  are disabled for a capture device. This makes it possible to
+  provide just one :c:type:`v4l2_ioctl_ops` struct for both vbi and
+  video nodes.
+
+- :c:type:`video_device`->lock: leave to ``NULL`` if you want to do all the
+  locking  in the driver. Otherwise you give it a pointer to a struct
+  ``mutex_lock`` and before the :c:type:`video_device`->unlocked_ioctl
+  file operation is called this lock will be taken by the core and released
+  afterwards. See the next section for more details.
+
+- :c:type:`video_device`->queue: a pointer to the struct :c:type:`vb2_queue`
+  associated with this device node.
+  If queue is not ``NULL``, and queue->lock is not ``NULL``, then queue->lock
+  is used for the queuing ioctls (``VIDIOC_REQBUFS``, ``CREATE_BUFS``,
+  ``QBUF``, ``DQBUF``,  ``QUERYBUF``, ``PREPARE_BUF``, ``STREAMON`` and
+  ``STREAMOFF``) instead of the lock above.
+  That way the :ref:`vb2 <vb2_framework>` queuing framework does not have
+  to wait for other ioctls.   This queue pointer is also used by the
+  :ref:`vb2 <vb2_framework>` helper functions to check for
+  queuing ownership (i.e. is the filehandle calling it allowed to do the
+  operation).
+
+- :c:type:`video_device`->prio: keeps track of the priorities. Used to
+  implement ``VIDIOC_G_PRIORITY`` and ``VIDIOC_S_PRIORITY``.
+  If left to ``NULL``, then it will use the struct :c:type:`v4l2_prio_state`
+  in :c:type:`v4l2_device`. If you want to have a separate priority state per
+  (group of) device node(s),   then you can point it to your own struct
+  :c:type:`v4l2_prio_state`.
+
+- :c:type:`video_device`->dev_parent: you only set this if v4l2_device was
+  registered with ``NULL`` as the parent ``device`` struct. This only happens
+  in cases where one hardware device has multiple PCI devices that all share
+  the same :c:type:`v4l2_device` core.
+
+  The cx88 driver is an example of this: one core :c:type:`v4l2_device` struct,
+  but   it is used by both a raw video PCI device (cx8800) and a MPEG PCI device
+  (cx8802). Since the :c:type:`v4l2_device` cannot be associated with two PCI
+  devices at the same time it is setup without a parent device. But when the
+  struct :c:type:`video_device` is initialized you **do** know which parent
+  PCI device to use and so you set ``dev_device`` to the correct PCI device.
+
+If you use :c:type:`v4l2_ioctl_ops`, then you should set
+:c:type:`video_device`->unlocked_ioctl to :c:func:`video_ioctl2` in your
+:c:type:`v4l2_file_operations` struct.
+
+In some cases you want to tell the core that a function you had specified in
+your :c:type:`v4l2_ioctl_ops` should be ignored. You can mark such ioctls by
+calling this function before :c:func:`video_register_device` is called:
+
+	:c:func:`v4l2_disable_ioctl <v4l2_disable_ioctl>`
+	(:c:type:`vdev <video_device>`, cmd).
+
+This tends to be needed if based on external factors (e.g. which card is
+being used) you want to turns off certain features in :c:type:`v4l2_ioctl_ops`
+without having to make a new struct.
+
+The :c:type:`v4l2_file_operations` struct is a subset of file_operations.
+The main difference is that the inode argument is omitted since it is never
+used.
+
+If integration with the media framework is needed, you must initialize the
+:c:type:`media_entity` struct embedded in the :c:type:`video_device` struct
+(entity field) by calling :c:func:`media_entity_pads_init`:
+
+.. code-block:: c
+
+	struct media_pad *pad = &my_vdev->pad;
+	int err;
+
+	err = media_entity_pads_init(&vdev->entity, 1, pad);
+
+The pads array must have been previously initialized. There is no need to
+manually set the struct media_entity type and name fields.
+
+A reference to the entity will be automatically acquired/released when the
+video device is opened/closed.
+
+ioctls and locking
+------------------
+
+The V4L core provides optional locking services. The main service is the
+lock field in struct :c:type:`video_device`, which is a pointer to a mutex.
+If you set this pointer, then that will be used by unlocked_ioctl to
+serialize all ioctls.
+
+If you are using the :ref:`videobuf2 framework <vb2_framework>`, then there
+is a second lock that you can set: :c:type:`video_device`->queue->lock. If
+set, then this lock will be used instead of :c:type:`video_device`->lock
+to serialize all queuing ioctls (see the previous section
+for the full list of those ioctls).
+
+The advantage of using a different lock for the queuing ioctls is that for some
+drivers (particularly USB drivers) certain commands such as setting controls
+can take a long time, so you want to use a separate lock for the buffer queuing
+ioctls. That way your ``VIDIOC_DQBUF`` doesn't stall because the driver is busy
+changing the e.g. exposure of the webcam.
+
+Of course, you can always do all the locking yourself by leaving both lock
+pointers at ``NULL``.
+
+If you use the old :ref:`videobuf framework <vb_framework>` then you must
+pass the :c:type:`video_device`->lock to the videobuf queue initialize
+function: if videobuf has to wait for a frame to arrive, then it will
+temporarily unlock the lock and relock it afterwards. If your driver also
+waits in the code, then you should do the same to allow other
+processes to access the device node while the first process is waiting for
+something.
+
+In the case of :ref:`videobuf2 <vb2_framework>` you will need to implement the
+``wait_prepare()`` and ``wait_finish()`` callbacks to unlock/lock if applicable.
+If you use the ``queue->lock`` pointer, then you can use the helper functions
+:c:func:`vb2_ops_wait_prepare` and :c:func:`vb2_ops_wait_finish`.
+
+The implementation of a hotplug disconnect should also take the lock from
+:c:type:`video_device` before calling v4l2_device_disconnect. If you are also
+using :c:type:`video_device`->queue->lock, then you have to first lock
+:c:type:`video_device`->queue->lock followed by :c:type:`video_device`->lock.
+That way you can be sure no ioctl is running when you call
+:c:func:`v4l2_device_disconnect`.
+
+Video device registration
+-------------------------
+
+Next you register the video device with :c:func:`video_register_device`.
+This will create the character device for you.
+
+.. code-block:: c
+
+	err = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
+	if (err) {
+		video_device_release(vdev); /* or kfree(my_vdev); */
+		return err;
+	}
+
+If the :c:type:`v4l2_device` parent device has a not ``NULL`` mdev field,
+the video device entity will be automatically registered with the media
+device.
+
+Which device is registered depends on the type argument. The following
+types exist:
+
+========================== ====================	 ==============================
+:c:type:`vfl_devnode_type` Device name		 Usage
+========================== ====================	 ==============================
+``VFL_TYPE_VIDEO``         ``/dev/videoX``       for video input/output devices
+``VFL_TYPE_VBI``           ``/dev/vbiX``         for vertical blank data (i.e.
+						 closed captions, teletext)
+``VFL_TYPE_RADIO``         ``/dev/radioX``       for radio tuners
+``VFL_TYPE_SUBDEV``        ``/dev/v4l-subdevX``  for V4L2 subdevices
+``VFL_TYPE_SDR``           ``/dev/swradioX``     for Software Defined Radio
+						 (SDR) tuners
+``VFL_TYPE_TOUCH``         ``/dev/v4l-touchX``   for touch sensors
+========================== ====================	 ==============================
+
+The last argument gives you a certain amount of control over the device
+device node number used (i.e. the X in ``videoX``). Normally you will pass -1
+to let the v4l2 framework pick the first free number. But sometimes users
+want to select a specific node number. It is common that drivers allow
+the user to select a specific device node number through a driver module
+option. That number is then passed to this function and video_register_device
+will attempt to select that device node number. If that number was already
+in use, then the next free device node number will be selected and it
+will send a warning to the kernel log.
+
+Another use-case is if a driver creates many devices. In that case it can
+be useful to place different video devices in separate ranges. For example,
+video capture devices start at 0, video output devices start at 16.
+So you can use the last argument to specify a minimum device node number
+and the v4l2 framework will try to pick the first free number that is equal
+or higher to what you passed. If that fails, then it will just pick the
+first free number.
+
+Since in this case you do not care about a warning about not being able
+to select the specified device node number, you can call the function
+:c:func:`video_register_device_no_warn` instead.
+
+Whenever a device node is created some attributes are also created for you.
+If you look in ``/sys/class/video4linux`` you see the devices. Go into e.g.
+``video0`` and you will see 'name', 'dev_debug' and 'index' attributes. The
+'name' attribute is the 'name' field of the video_device struct. The
+'dev_debug' attribute can be used to enable core debugging. See the next
+section for more detailed information on this.
+
+The 'index' attribute is the index of the device node: for each call to
+:c:func:`video_register_device()` the index is just increased by 1. The
+first video device node you register always starts with index 0.
+
+Users can setup udev rules that utilize the index attribute to make fancy
+device names (e.g. '``mpegX``' for MPEG video capture device nodes).
+
+After the device was successfully registered, then you can use these fields:
+
+- :c:type:`video_device`->vfl_type: the device type passed to
+  :c:func:`video_register_device`.
+- :c:type:`video_device`->minor: the assigned device minor number.
+- :c:type:`video_device`->num: the device node number (i.e. the X in
+  ``videoX``).
+- :c:type:`video_device`->index: the device index number.
+
+If the registration failed, then you need to call
+:c:func:`video_device_release` to free the allocated :c:type:`video_device`
+struct, or free your own struct if the :c:type:`video_device` was embedded in
+it. The ``vdev->release()`` callback will never be called if the registration
+failed, nor should you ever attempt to unregister the device if the
+registration failed.
+
+video device debugging
+----------------------
+
+The 'dev_debug' attribute that is created for each video, vbi, radio or swradio
+device in ``/sys/class/video4linux/<devX>/`` allows you to enable logging of
+file operations.
+
+It is a bitmask and the following bits can be set:
+
+.. tabularcolumns:: |p{5ex}|L|
+
+===== ================================================================
+Mask  Description
+===== ================================================================
+0x01  Log the ioctl name and error code. VIDIOC_(D)QBUF ioctls are
+      only logged if bit 0x08 is also set.
+0x02  Log the ioctl name arguments and error code. VIDIOC_(D)QBUF
+      ioctls are
+      only logged if bit 0x08 is also set.
+0x04  Log the file operations open, release, read, write, mmap and
+      get_unmapped_area. The read and write operations are only
+      logged if bit 0x08 is also set.
+0x08  Log the read and write file operations and the VIDIOC_QBUF and
+      VIDIOC_DQBUF ioctls.
+0x10  Log the poll file operation.
+0x20  Log error and messages in the control operations.
+===== ================================================================
+
+Video device cleanup
+--------------------
+
+When the video device nodes have to be removed, either during the unload
+of the driver or because the USB device was disconnected, then you should
+unregister them with:
+
+	:c:func:`video_unregister_device`
+	(:c:type:`vdev <video_device>`);
+
+This will remove the device nodes from sysfs (causing udev to remove them
+from ``/dev``).
+
+After :c:func:`video_unregister_device` returns no new opens can be done.
+However, in the case of USB devices some application might still have one of
+these device nodes open. So after the unregister all file operations (except
+release, of course) will return an error as well.
+
+When the last user of the video device node exits, then the ``vdev->release()``
+callback is called and you can do the final cleanup there.
+
+Don't forget to cleanup the media entity associated with the video device if
+it has been initialized:
+
+	:c:func:`media_entity_cleanup <media_entity_cleanup>`
+	(&vdev->entity);
+
+This can be done from the release callback.
+
+
+helper functions
+----------------
+
+There are a few useful helper functions:
+
+- file and :c:type:`video_device` private data
+
+You can set/get driver private data in the video_device struct using:
+
+	:c:func:`video_get_drvdata <video_get_drvdata>`
+	(:c:type:`vdev <video_device>`);
+
+	:c:func:`video_set_drvdata <video_set_drvdata>`
+	(:c:type:`vdev <video_device>`);
+
+Note that you can safely call :c:func:`video_set_drvdata` before calling
+:c:func:`video_register_device`.
+
+And this function:
+
+	:c:func:`video_devdata <video_devdata>`
+	(struct file \*file);
+
+returns the video_device belonging to the file struct.
+
+The :c:func:`video_devdata` function combines :c:func:`video_get_drvdata`
+with :c:func:`video_devdata`:
+
+	:c:func:`video_drvdata <video_drvdata>`
+	(struct file \*file);
+
+You can go from a :c:type:`video_device` struct to the v4l2_device struct using:
+
+.. code-block:: c
+
+	struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
+
+- Device node name
+
+The :c:type:`video_device` node kernel name can be retrieved using:
+
+	:c:func:`video_device_node_name <video_device_node_name>`
+	(:c:type:`vdev <video_device>`);
+
+The name is used as a hint by userspace tools such as udev. The function
+should be used where possible instead of accessing the video_device::num and
+video_device::minor fields.
+
+video_device functions and data structures
+------------------------------------------
+
+.. kernel-doc:: include/media/v4l2-dev.h
diff --git a/Documentation/driver-api/media/v4l2-device.rst b/Documentation/driver-api/media/v4l2-device.rst
new file mode 100644
index 000000000000..5e25bf182c18
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-device.rst
@@ -0,0 +1,146 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 device instance
+--------------------
+
+Each device instance is represented by a struct :c:type:`v4l2_device`.
+Very simple devices can just allocate this struct, but most of the time you
+would embed this struct inside a larger struct.
+
+You must register the device instance by calling:
+
+	:c:func:`v4l2_device_register <v4l2_device_register>`
+	(dev, :c:type:`v4l2_dev <v4l2_device>`).
+
+Registration will initialize the :c:type:`v4l2_device` struct. If the
+dev->driver_data field is ``NULL``, it will be linked to
+:c:type:`v4l2_dev <v4l2_device>` argument.
+
+Drivers that want integration with the media device framework need to set
+dev->driver_data manually to point to the driver-specific device structure
+that embed the struct :c:type:`v4l2_device` instance. This is achieved by a
+``dev_set_drvdata()`` call before registering the V4L2 device instance.
+They must also set the struct :c:type:`v4l2_device` mdev field to point to a
+properly initialized and registered :c:type:`media_device` instance.
+
+If :c:type:`v4l2_dev <v4l2_device>`\ ->name is empty then it will be set to a
+value derived from dev (driver name followed by the bus_id, to be precise).
+If you set it up before  calling :c:func:`v4l2_device_register` then it will
+be untouched. If dev is ``NULL``, then you **must** setup
+:c:type:`v4l2_dev <v4l2_device>`\ ->name before calling
+:c:func:`v4l2_device_register`.
+
+You can use :c:func:`v4l2_device_set_name` to set the name based on a driver
+name and a driver-global atomic_t instance. This will generate names like
+``ivtv0``, ``ivtv1``, etc. If the name ends with a digit, then it will insert
+a dash: ``cx18-0``, ``cx18-1``, etc. This function returns the instance number.
+
+The first ``dev`` argument is normally the ``struct device`` pointer of a
+``pci_dev``, ``usb_interface`` or ``platform_device``. It is rare for dev to
+be ``NULL``, but it happens with ISA devices or when one device creates
+multiple PCI devices, thus making it impossible to associate
+:c:type:`v4l2_dev <v4l2_device>` with a particular parent.
+
+You can also supply a ``notify()`` callback that can be called by sub-devices
+to notify you of events. Whether you need to set this depends on the
+sub-device. Any notifications a sub-device supports must be defined in a header
+in ``include/media/subdevice.h``.
+
+V4L2 devices are unregistered by calling:
+
+	:c:func:`v4l2_device_unregister`
+	(:c:type:`v4l2_dev <v4l2_device>`).
+
+If the dev->driver_data field points to :c:type:`v4l2_dev <v4l2_device>`,
+it will be reset to ``NULL``. Unregistering will also automatically unregister
+all subdevs from the device.
+
+If you have a hotpluggable device (e.g. a USB device), then when a disconnect
+happens the parent device becomes invalid. Since :c:type:`v4l2_device` has a
+pointer to that parent device it has to be cleared as well to mark that the
+parent is gone. To do this call:
+
+	:c:func:`v4l2_device_disconnect`
+	(:c:type:`v4l2_dev <v4l2_device>`).
+
+This does *not* unregister the subdevs, so you still need to call the
+:c:func:`v4l2_device_unregister` function for that. If your driver is not
+hotpluggable, then there is no need to call :c:func:`v4l2_device_disconnect`.
+
+Sometimes you need to iterate over all devices registered by a specific
+driver. This is usually the case if multiple device drivers use the same
+hardware. E.g. the ivtvfb driver is a framebuffer driver that uses the ivtv
+hardware. The same is true for alsa drivers for example.
+
+You can iterate over all registered devices as follows:
+
+.. code-block:: c
+
+	static int callback(struct device *dev, void *p)
+	{
+		struct v4l2_device *v4l2_dev = dev_get_drvdata(dev);
+
+		/* test if this device was inited */
+		if (v4l2_dev == NULL)
+			return 0;
+		...
+		return 0;
+	}
+
+	int iterate(void *p)
+	{
+		struct device_driver *drv;
+		int err;
+
+		/* Find driver 'ivtv' on the PCI bus.
+		pci_bus_type is a global. For USB buses use usb_bus_type. */
+		drv = driver_find("ivtv", &pci_bus_type);
+		/* iterate over all ivtv device instances */
+		err = driver_for_each_device(drv, NULL, p, callback);
+		put_driver(drv);
+		return err;
+	}
+
+Sometimes you need to keep a running counter of the device instance. This is
+commonly used to map a device instance to an index of a module option array.
+
+The recommended approach is as follows:
+
+.. code-block:: c
+
+	static atomic_t drv_instance = ATOMIC_INIT(0);
+
+	static int drv_probe(struct pci_dev *pdev, const struct pci_device_id *pci_id)
+	{
+		...
+		state->instance = atomic_inc_return(&drv_instance) - 1;
+	}
+
+If you have multiple device nodes then it can be difficult to know when it is
+safe to unregister :c:type:`v4l2_device` for hotpluggable devices. For this
+purpose :c:type:`v4l2_device` has refcounting support. The refcount is
+increased whenever :c:func:`video_register_device` is called and it is
+decreased whenever that device node is released. When the refcount reaches
+zero, then the :c:type:`v4l2_device` release() callback is called. You can
+do your final cleanup there.
+
+If other device nodes (e.g. ALSA) are created, then you can increase and
+decrease the refcount manually as well by calling:
+
+	:c:func:`v4l2_device_get`
+	(:c:type:`v4l2_dev <v4l2_device>`).
+
+or:
+
+	:c:func:`v4l2_device_put`
+	(:c:type:`v4l2_dev <v4l2_device>`).
+
+Since the initial refcount is 1 you also need to call
+:c:func:`v4l2_device_put` in the ``disconnect()`` callback (for USB devices)
+or in the ``remove()`` callback (for e.g. PCI devices), otherwise the refcount
+will never reach 0.
+
+v4l2_device functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-device.h
diff --git a/Documentation/driver-api/media/v4l2-dv-timings.rst b/Documentation/driver-api/media/v4l2-dv-timings.rst
new file mode 100644
index 000000000000..b178f931518b
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-dv-timings.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 DV Timings functions
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-dv-timings.h
diff --git a/Documentation/driver-api/media/v4l2-event.rst b/Documentation/driver-api/media/v4l2-event.rst
new file mode 100644
index 000000000000..a4b7ae2b94d8
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-event.rst
@@ -0,0 +1,181 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 events
+-----------
+
+The V4L2 events provide a generic way to pass events to user space.
+The driver must use :c:type:`v4l2_fh` to be able to support V4L2 events.
+
+Events are subscribed per-filehandle. An event specification consists of a
+``type`` and is optionally associated with an object identified through the
+``id`` field. If unused, then the ``id`` is 0. So an event is uniquely
+identified by the ``(type, id)`` tuple.
+
+The :c:type:`v4l2_fh` struct has a list of subscribed events on its
+``subscribed`` field.
+
+When the user subscribes to an event, a :c:type:`v4l2_subscribed_event`
+struct is added to :c:type:`v4l2_fh`\ ``.subscribed``, one for every
+subscribed event.
+
+Each :c:type:`v4l2_subscribed_event` struct ends with a
+:c:type:`v4l2_kevent` ringbuffer, with the size given by the caller
+of :c:func:`v4l2_event_subscribe`. This ringbuffer is used to store any events
+raised by the driver.
+
+So every ``(type, ID)`` event tuple will have its own
+:c:type:`v4l2_kevent` ringbuffer. This guarantees that if a driver is
+generating lots of events of one type in a short time, then that will
+not overwrite events of another type.
+
+But if you get more events of one type than the size of the
+:c:type:`v4l2_kevent` ringbuffer, then the oldest event will be dropped
+and the new one added.
+
+The :c:type:`v4l2_kevent` struct links into the ``available``
+list of the :c:type:`v4l2_fh` struct so :ref:`VIDIOC_DQEVENT` will
+know which event to dequeue first.
+
+Finally, if the event subscription is associated with a particular object
+such as a V4L2 control, then that object needs to know about that as well
+so that an event can be raised by that object. So the ``node`` field can
+be used to link the :c:type:`v4l2_subscribed_event` struct into a list of
+such objects.
+
+So to summarize:
+
+- struct :c:type:`v4l2_fh` has two lists: one of the ``subscribed`` events,
+  and one of the ``available`` events.
+
+- struct :c:type:`v4l2_subscribed_event` has a ringbuffer of raised
+  (pending) events of that particular type.
+
+- If struct :c:type:`v4l2_subscribed_event` is associated with a specific
+  object, then that object will have an internal list of
+  struct :c:type:`v4l2_subscribed_event` so it knows who subscribed an
+  event to that object.
+
+Furthermore, the internal struct :c:type:`v4l2_subscribed_event` has
+``merge()`` and ``replace()`` callbacks which drivers can set. These
+callbacks are called when a new event is raised and there is no more room.
+
+The ``replace()`` callback allows you to replace the payload of the old event
+with that of the new event, merging any relevant data from the old payload
+into the new payload that replaces it. It is called when this event type has
+a ringbuffer with size is one, i.e. only one event can be stored in the
+ringbuffer.
+
+The ``merge()`` callback allows you to merge the oldest event payload into
+that of the second-oldest event payload. It is called when
+the ringbuffer has size is greater than one.
+
+This way no status information is lost, just the intermediate steps leading
+up to that state.
+
+A good example of these ``replace``/``merge`` callbacks is in v4l2-event.c:
+``ctrls_replace()`` and ``ctrls_merge()`` callbacks for the control event.
+
+.. note::
+	these callbacks can be called from interrupt context, so they must
+	be fast.
+
+In order to queue events to video device, drivers should call:
+
+	:c:func:`v4l2_event_queue <v4l2_event_queue>`
+	(:c:type:`vdev <video_device>`, :c:type:`ev <v4l2_event>`)
+
+The driver's only responsibility is to fill in the type and the data fields.
+The other fields will be filled in by V4L2.
+
+Event subscription
+~~~~~~~~~~~~~~~~~~
+
+Subscribing to an event is via:
+
+	:c:func:`v4l2_event_subscribe <v4l2_event_subscribe>`
+	(:c:type:`fh <v4l2_fh>`, :c:type:`sub <v4l2_event_subscription>` ,
+	elems, :c:type:`ops <v4l2_subscribed_event_ops>`)
+
+
+This function is used to implement :c:type:`video_device`->
+:c:type:`ioctl_ops <v4l2_ioctl_ops>`-> ``vidioc_subscribe_event``,
+but the driver must check first if the driver is able to produce events
+with specified event id, and then should call
+:c:func:`v4l2_event_subscribe` to subscribe the event.
+
+The elems argument is the size of the event queue for this event. If it is 0,
+then the framework will fill in a default value (this depends on the event
+type).
+
+The ops argument allows the driver to specify a number of callbacks:
+
+.. tabularcolumns:: |p{1.5cm}|p{16.0cm}|
+
+======== ==============================================================
+Callback Description
+======== ==============================================================
+add      called when a new listener gets added (subscribing to the same
+	 event twice will only cause this callback to get called once)
+del      called when a listener stops listening
+replace  replace event 'old' with event 'new'.
+merge    merge event 'old' into event 'new'.
+======== ==============================================================
+
+All 4 callbacks are optional, if you don't want to specify any callbacks
+the ops argument itself maybe ``NULL``.
+
+Unsubscribing an event
+~~~~~~~~~~~~~~~~~~~~~~
+
+Unsubscribing to an event is via:
+
+	:c:func:`v4l2_event_unsubscribe <v4l2_event_unsubscribe>`
+	(:c:type:`fh <v4l2_fh>`, :c:type:`sub <v4l2_event_subscription>`)
+
+This function is used to implement :c:type:`video_device`->
+:c:type:`ioctl_ops <v4l2_ioctl_ops>`-> ``vidioc_unsubscribe_event``.
+A driver may call :c:func:`v4l2_event_unsubscribe` directly unless it
+wants to be involved in unsubscription process.
+
+The special type ``V4L2_EVENT_ALL`` may be used to unsubscribe all events. The
+drivers may want to handle this in a special way.
+
+Check if there's a pending event
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Checking if there's a pending event is via:
+
+	:c:func:`v4l2_event_pending <v4l2_event_pending>`
+	(:c:type:`fh <v4l2_fh>`)
+
+
+This function returns the number of pending events. Useful when implementing
+poll.
+
+How events work
+~~~~~~~~~~~~~~~
+
+Events are delivered to user space through the poll system call. The driver
+can use :c:type:`v4l2_fh`->wait (a wait_queue_head_t) as the argument for
+``poll_wait()``.
+
+There are standard and private events. New standard events must use the
+smallest available event type. The drivers must allocate their events from
+their own class starting from class base. Class base is
+``V4L2_EVENT_PRIVATE_START`` + n * 1000 where n is the lowest available number.
+The first event type in the class is reserved for future use, so the first
+available event type is 'class base + 1'.
+
+An example on how the V4L2 events may be used can be found in the OMAP
+3 ISP driver (``drivers/media/platform/omap3isp``).
+
+A subdev can directly send an event to the :c:type:`v4l2_device` notify
+function with ``V4L2_DEVICE_NOTIFY_EVENT``. This allows the bridge to map
+the subdev that sends the event to the video node(s) associated with the
+subdev that need to be informed about such an event.
+
+V4L2 event functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-event.h
+
diff --git a/Documentation/driver-api/media/v4l2-fh.rst b/Documentation/driver-api/media/v4l2-fh.rst
new file mode 100644
index 000000000000..4c62b19af744
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-fh.rst
@@ -0,0 +1,141 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 File handlers
+------------------
+
+struct :c:type:`v4l2_fh` provides a way to easily keep file handle specific
+data that is used by the V4L2 framework.
+
+.. attention::
+	New drivers must use struct :c:type:`v4l2_fh`
+	since it is also used to implement priority handling
+	(:ref:`VIDIOC_G_PRIORITY`).
+
+The users of :c:type:`v4l2_fh` (in the V4L2 framework, not the driver) know
+whether a driver uses :c:type:`v4l2_fh` as its ``file->private_data`` pointer
+by testing the ``V4L2_FL_USES_V4L2_FH`` bit in :c:type:`video_device`->flags.
+This bit is set whenever :c:func:`v4l2_fh_init` is called.
+
+struct :c:type:`v4l2_fh` is allocated as a part of the driver's own file handle
+structure and ``file->private_data`` is set to it in the driver's ``open()``
+function by the driver.
+
+In many cases the struct :c:type:`v4l2_fh` will be embedded in a larger
+structure. In that case you should call:
+
+#) :c:func:`v4l2_fh_init` and :c:func:`v4l2_fh_add` in ``open()``
+#) :c:func:`v4l2_fh_del` and :c:func:`v4l2_fh_exit` in ``release()``
+
+Drivers can extract their own file handle structure by using the container_of
+macro.
+
+Example:
+
+.. code-block:: c
+
+	struct my_fh {
+		int blah;
+		struct v4l2_fh fh;
+	};
+
+	...
+
+	int my_open(struct file *file)
+	{
+		struct my_fh *my_fh;
+		struct video_device *vfd;
+		int ret;
+
+		...
+
+		my_fh = kzalloc(sizeof(*my_fh), GFP_KERNEL);
+
+		...
+
+		v4l2_fh_init(&my_fh->fh, vfd);
+
+		...
+
+		file->private_data = &my_fh->fh;
+		v4l2_fh_add(&my_fh->fh);
+		return 0;
+	}
+
+	int my_release(struct file *file)
+	{
+		struct v4l2_fh *fh = file->private_data;
+		struct my_fh *my_fh = container_of(fh, struct my_fh, fh);
+
+		...
+		v4l2_fh_del(&my_fh->fh);
+		v4l2_fh_exit(&my_fh->fh);
+		kfree(my_fh);
+		return 0;
+	}
+
+Below is a short description of the :c:type:`v4l2_fh` functions used:
+
+:c:func:`v4l2_fh_init <v4l2_fh_init>`
+(:c:type:`fh <v4l2_fh>`, :c:type:`vdev <video_device>`)
+
+
+- Initialise the file handle. This **MUST** be performed in the driver's
+  :c:type:`v4l2_file_operations`->open() handler.
+
+
+:c:func:`v4l2_fh_add <v4l2_fh_add>`
+(:c:type:`fh <v4l2_fh>`)
+
+- Add a :c:type:`v4l2_fh` to :c:type:`video_device` file handle list.
+  Must be called once the file handle is completely initialized.
+
+:c:func:`v4l2_fh_del <v4l2_fh_del>`
+(:c:type:`fh <v4l2_fh>`)
+
+- Unassociate the file handle from :c:type:`video_device`. The file handle
+  exit function may now be called.
+
+:c:func:`v4l2_fh_exit <v4l2_fh_exit>`
+(:c:type:`fh <v4l2_fh>`)
+
+- Uninitialise the file handle. After uninitialisation the :c:type:`v4l2_fh`
+  memory can be freed.
+
+
+If struct :c:type:`v4l2_fh` is not embedded, then you can use these helper functions:
+
+:c:func:`v4l2_fh_open <v4l2_fh_open>`
+(struct file \*filp)
+
+- This allocates a struct :c:type:`v4l2_fh`, initializes it and adds it to
+  the struct :c:type:`video_device` associated with the file struct.
+
+:c:func:`v4l2_fh_release <v4l2_fh_release>`
+(struct file \*filp)
+
+- This deletes it from the struct :c:type:`video_device` associated with the
+  file struct, uninitialised the :c:type:`v4l2_fh` and frees it.
+
+These two functions can be plugged into the v4l2_file_operation's ``open()``
+and ``release()`` ops.
+
+Several drivers need to do something when the first file handle is opened and
+when the last file handle closes. Two helper functions were added to check
+whether the :c:type:`v4l2_fh` struct is the only open filehandle of the
+associated device node:
+
+:c:func:`v4l2_fh_is_singular <v4l2_fh_is_singular>`
+(:c:type:`fh <v4l2_fh>`)
+
+-  Returns 1 if the file handle is the only open file handle, else 0.
+
+:c:func:`v4l2_fh_is_singular_file <v4l2_fh_is_singular_file>`
+(struct file \*filp)
+
+- Same, but it calls v4l2_fh_is_singular with filp->private_data.
+
+
+V4L2 fh functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-fh.h
diff --git a/Documentation/driver-api/media/v4l2-flash-led-class.rst b/Documentation/driver-api/media/v4l2-flash-led-class.rst
new file mode 100644
index 000000000000..2aa6bed9b8db
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-flash-led-class.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 flash functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-flash-led-class.h
diff --git a/Documentation/driver-api/media/v4l2-fwnode.rst b/Documentation/driver-api/media/v4l2-fwnode.rst
new file mode 100644
index 000000000000..e313b6cddcd0
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-fwnode.rst
@@ -0,0 +1,5 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 fwnode kAPI
+^^^^^^^^^^^^^^^^
+.. kernel-doc:: include/media/v4l2-fwnode.h
diff --git a/Documentation/driver-api/media/v4l2-intro.rst b/Documentation/driver-api/media/v4l2-intro.rst
new file mode 100644
index 000000000000..4d54fa9d7a12
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-intro.rst
@@ -0,0 +1,76 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Introduction
+------------
+
+The V4L2 drivers tend to be very complex due to the complexity of the
+hardware: most devices have multiple ICs, export multiple device nodes in
+/dev, and create also non-V4L2 devices such as DVB, ALSA, FB, I2C and input
+(IR) devices.
+
+Especially the fact that V4L2 drivers have to setup supporting ICs to
+do audio/video muxing/encoding/decoding makes it more complex than most.
+Usually these ICs are connected to the main bridge driver through one or
+more I2C buses, but other buses can also be used. Such devices are
+called 'sub-devices'.
+
+For a long time the framework was limited to the video_device struct for
+creating V4L device nodes and video_buf for handling the video buffers
+(note that this document does not discuss the video_buf framework).
+
+This meant that all drivers had to do the setup of device instances and
+connecting to sub-devices themselves. Some of this is quite complicated
+to do right and many drivers never did do it correctly.
+
+There is also a lot of common code that could never be refactored due to
+the lack of a framework.
+
+So this framework sets up the basic building blocks that all drivers
+need and this same framework should make it much easier to refactor
+common code into utility functions shared by all drivers.
+
+A good example to look at as a reference is the v4l2-pci-skeleton.c
+source that is available in samples/v4l/. It is a skeleton driver for
+a PCI capture card, and demonstrates how to use the V4L2 driver
+framework. It can be used as a template for real PCI video capture driver.
+
+Structure of a V4L driver
+-------------------------
+
+All drivers have the following structure:
+
+1) A struct for each device instance containing the device state.
+
+2) A way of initializing and commanding sub-devices (if any).
+
+3) Creating V4L2 device nodes (/dev/videoX, /dev/vbiX and /dev/radioX)
+   and keeping track of device-node specific data.
+
+4) Filehandle-specific structs containing per-filehandle data;
+
+5) video buffer handling.
+
+This is a rough schematic of how it all relates:
+
+.. code-block:: none
+
+    device instances
+      |
+      +-sub-device instances
+      |
+      \-V4L2 device nodes
+	  |
+	  \-filehandle instances
+
+
+Structure of the V4L2 framework
+-------------------------------
+
+The framework closely resembles the driver structure: it has a v4l2_device
+struct for the device instance data, a v4l2_subdev struct to refer to
+sub-device instances, the video_device struct stores V4L2 device node data
+and the v4l2_fh struct keeps track of filehandle instances.
+
+The V4L2 framework also optionally integrates with the media framework. If a
+driver sets the struct v4l2_device mdev field, sub-devices and video nodes
+will automatically appear in the media framework as entities.
diff --git a/Documentation/driver-api/media/v4l2-mc.rst b/Documentation/driver-api/media/v4l2-mc.rst
new file mode 100644
index 000000000000..0c352ac588b2
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-mc.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 Media Controller functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-mc.h
diff --git a/Documentation/driver-api/media/v4l2-mediabus.rst b/Documentation/driver-api/media/v4l2-mediabus.rst
new file mode 100644
index 000000000000..1f2254cba92d
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-mediabus.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 Media Bus functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-mediabus.h
diff --git a/Documentation/driver-api/media/v4l2-mem2mem.rst b/Documentation/driver-api/media/v4l2-mem2mem.rst
new file mode 100644
index 000000000000..a43b31cc8261
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-mem2mem.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 Memory to Memory functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-mem2mem.h
diff --git a/Documentation/driver-api/media/v4l2-rect.rst b/Documentation/driver-api/media/v4l2-rect.rst
new file mode 100644
index 000000000000..fc315cd84156
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-rect.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 rect helper functions
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/v4l2-rect.h
diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst
new file mode 100644
index 000000000000..29e07e23f888
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-subdev.rst
@@ -0,0 +1,444 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 sub-devices
+----------------
+
+Many drivers need to communicate with sub-devices. These devices can do all
+sort of tasks, but most commonly they handle audio and/or video muxing,
+encoding or decoding. For webcams common sub-devices are sensors and camera
+controllers.
+
+Usually these are I2C devices, but not necessarily. In order to provide the
+driver with a consistent interface to these sub-devices the
+:c:type:`v4l2_subdev` struct (v4l2-subdev.h) was created.
+
+Each sub-device driver must have a :c:type:`v4l2_subdev` struct. This struct
+can be stand-alone for simple sub-devices or it might be embedded in a larger
+struct if more state information needs to be stored. Usually there is a
+low-level device struct (e.g. ``i2c_client``) that contains the device data as
+setup by the kernel. It is recommended to store that pointer in the private
+data of :c:type:`v4l2_subdev` using :c:func:`v4l2_set_subdevdata`. That makes
+it easy to go from a :c:type:`v4l2_subdev` to the actual low-level bus-specific
+device data.
+
+You also need a way to go from the low-level struct to :c:type:`v4l2_subdev`.
+For the common i2c_client struct the i2c_set_clientdata() call is used to store
+a :c:type:`v4l2_subdev` pointer, for other buses you may have to use other
+methods.
+
+Bridges might also need to store per-subdev private data, such as a pointer to
+bridge-specific per-subdev private data. The :c:type:`v4l2_subdev` structure
+provides host private data for that purpose that can be accessed with
+:c:func:`v4l2_get_subdev_hostdata` and :c:func:`v4l2_set_subdev_hostdata`.
+
+From the bridge driver perspective, you load the sub-device module and somehow
+obtain the :c:type:`v4l2_subdev` pointer. For i2c devices this is easy: you call
+``i2c_get_clientdata()``. For other buses something similar needs to be done.
+Helper functions exists for sub-devices on an I2C bus that do most of this
+tricky work for you.
+
+Each :c:type:`v4l2_subdev` contains function pointers that sub-device drivers
+can implement (or leave ``NULL`` if it is not applicable). Since sub-devices can
+do so many different things and you do not want to end up with a huge ops struct
+of which only a handful of ops are commonly implemented, the function pointers
+are sorted according to category and each category has its own ops struct.
+
+The top-level ops struct contains pointers to the category ops structs, which
+may be NULL if the subdev driver does not support anything from that category.
+
+It looks like this:
+
+.. code-block:: c
+
+	struct v4l2_subdev_core_ops {
+		int (*log_status)(struct v4l2_subdev *sd);
+		int (*init)(struct v4l2_subdev *sd, u32 val);
+		...
+	};
+
+	struct v4l2_subdev_tuner_ops {
+		...
+	};
+
+	struct v4l2_subdev_audio_ops {
+		...
+	};
+
+	struct v4l2_subdev_video_ops {
+		...
+	};
+
+	struct v4l2_subdev_pad_ops {
+		...
+	};
+
+	struct v4l2_subdev_ops {
+		const struct v4l2_subdev_core_ops  *core;
+		const struct v4l2_subdev_tuner_ops *tuner;
+		const struct v4l2_subdev_audio_ops *audio;
+		const struct v4l2_subdev_video_ops *video;
+		const struct v4l2_subdev_pad_ops *video;
+	};
+
+The core ops are common to all subdevs, the other categories are implemented
+depending on the sub-device. E.g. a video device is unlikely to support the
+audio ops and vice versa.
+
+This setup limits the number of function pointers while still making it easy
+to add new ops and categories.
+
+A sub-device driver initializes the :c:type:`v4l2_subdev` struct using:
+
+	:c:func:`v4l2_subdev_init <v4l2_subdev_init>`
+	(:c:type:`sd <v4l2_subdev>`, &\ :c:type:`ops <v4l2_subdev_ops>`).
+
+
+Afterwards you need to initialize :c:type:`sd <v4l2_subdev>`->name with a
+unique name and set the module owner. This is done for you if you use the
+i2c helper functions.
+
+If integration with the media framework is needed, you must initialize the
+:c:type:`media_entity` struct embedded in the :c:type:`v4l2_subdev` struct
+(entity field) by calling :c:func:`media_entity_pads_init`, if the entity has
+pads:
+
+.. code-block:: c
+
+	struct media_pad *pads = &my_sd->pads;
+	int err;
+
+	err = media_entity_pads_init(&sd->entity, npads, pads);
+
+The pads array must have been previously initialized. There is no need to
+manually set the struct :c:type:`media_entity` function and name fields, but the
+revision field must be initialized if needed.
+
+A reference to the entity will be automatically acquired/released when the
+subdev device node (if any) is opened/closed.
+
+Don't forget to cleanup the media entity before the sub-device is destroyed:
+
+.. code-block:: c
+
+	media_entity_cleanup(&sd->entity);
+
+If the subdev driver intends to process video and integrate with the media
+framework, it must implement format related functionality using
+:c:type:`v4l2_subdev_pad_ops` instead of :c:type:`v4l2_subdev_video_ops`.
+
+In that case, the subdev driver may set the link_validate field to provide
+its own link validation function. The link validation function is called for
+every link in the pipeline where both of the ends of the links are V4L2
+sub-devices. The driver is still responsible for validating the correctness
+of the format configuration between sub-devices and video nodes.
+
+If link_validate op is not set, the default function
+:c:func:`v4l2_subdev_link_validate_default` is used instead. This function
+ensures that width, height and the media bus pixel code are equal on both source
+and sink of the link. Subdev drivers are also free to use this function to
+perform the checks mentioned above in addition to their own checks.
+
+There are currently two ways to register subdevices with the V4L2 core. The
+first (traditional) possibility is to have subdevices registered by bridge
+drivers. This can be done when the bridge driver has the complete information
+about subdevices connected to it and knows exactly when to register them. This
+is typically the case for internal subdevices, like video data processing units
+within SoCs or complex PCI(e) boards, camera sensors in USB cameras or connected
+to SoCs, which pass information about them to bridge drivers, usually in their
+platform data.
+
+There are however also situations where subdevices have to be registered
+asynchronously to bridge devices. An example of such a configuration is a Device
+Tree based system where information about subdevices is made available to the
+system independently from the bridge devices, e.g. when subdevices are defined
+in DT as I2C device nodes. The API used in this second case is described further
+below.
+
+Using one or the other registration method only affects the probing process, the
+run-time bridge-subdevice interaction is in both cases the same.
+
+In the synchronous case a device (bridge) driver needs to register the
+:c:type:`v4l2_subdev` with the v4l2_device:
+
+	:c:func:`v4l2_device_register_subdev <v4l2_device_register_subdev>`
+	(:c:type:`v4l2_dev <v4l2_device>`, :c:type:`sd <v4l2_subdev>`).
+
+This can fail if the subdev module disappeared before it could be registered.
+After this function was called successfully the subdev->dev field points to
+the :c:type:`v4l2_device`.
+
+If the v4l2_device parent device has a non-NULL mdev field, the sub-device
+entity will be automatically registered with the media device.
+
+You can unregister a sub-device using:
+
+	:c:func:`v4l2_device_unregister_subdev <v4l2_device_unregister_subdev>`
+	(:c:type:`sd <v4l2_subdev>`).
+
+
+Afterwards the subdev module can be unloaded and
+:c:type:`sd <v4l2_subdev>`->dev == ``NULL``.
+
+You can call an ops function either directly:
+
+.. code-block:: c
+
+	err = sd->ops->core->g_std(sd, &norm);
+
+but it is better and easier to use this macro:
+
+.. code-block:: c
+
+	err = v4l2_subdev_call(sd, core, g_std, &norm);
+
+The macro will to the right ``NULL`` pointer checks and returns ``-ENODEV``
+if :c:type:`sd <v4l2_subdev>` is ``NULL``, ``-ENOIOCTLCMD`` if either
+:c:type:`sd <v4l2_subdev>`->core or :c:type:`sd <v4l2_subdev>`->core->g_std is ``NULL``, or the actual result of the
+:c:type:`sd <v4l2_subdev>`->ops->core->g_std ops.
+
+It is also possible to call all or a subset of the sub-devices:
+
+.. code-block:: c
+
+	v4l2_device_call_all(v4l2_dev, 0, core, g_std, &norm);
+
+Any subdev that does not support this ops is skipped and error results are
+ignored. If you want to check for errors use this:
+
+.. code-block:: c
+
+	err = v4l2_device_call_until_err(v4l2_dev, 0, core, g_std, &norm);
+
+Any error except ``-ENOIOCTLCMD`` will exit the loop with that error. If no
+errors (except ``-ENOIOCTLCMD``) occurred, then 0 is returned.
+
+The second argument to both calls is a group ID. If 0, then all subdevs are
+called. If non-zero, then only those whose group ID match that value will
+be called. Before a bridge driver registers a subdev it can set
+:c:type:`sd <v4l2_subdev>`->grp_id to whatever value it wants (it's 0 by
+default). This value is owned by the bridge driver and the sub-device driver
+will never modify or use it.
+
+The group ID gives the bridge driver more control how callbacks are called.
+For example, there may be multiple audio chips on a board, each capable of
+changing the volume. But usually only one will actually be used when the
+user want to change the volume. You can set the group ID for that subdev to
+e.g. AUDIO_CONTROLLER and specify that as the group ID value when calling
+``v4l2_device_call_all()``. That ensures that it will only go to the subdev
+that needs it.
+
+If the sub-device needs to notify its v4l2_device parent of an event, then
+it can call ``v4l2_subdev_notify(sd, notification, arg)``. This macro checks
+whether there is a ``notify()`` callback defined and returns ``-ENODEV`` if not.
+Otherwise the result of the ``notify()`` call is returned.
+
+The advantage of using :c:type:`v4l2_subdev` is that it is a generic struct and
+does not contain any knowledge about the underlying hardware. So a driver might
+contain several subdevs that use an I2C bus, but also a subdev that is
+controlled through GPIO pins. This distinction is only relevant when setting
+up the device, but once the subdev is registered it is completely transparent.
+
+In the asynchronous case subdevice probing can be invoked independently of the
+bridge driver availability. The subdevice driver then has to verify whether all
+the requirements for a successful probing are satisfied. This can include a
+check for a master clock availability. If any of the conditions aren't satisfied
+the driver might decide to return ``-EPROBE_DEFER`` to request further reprobing
+attempts. Once all conditions are met the subdevice shall be registered using
+the :c:func:`v4l2_async_register_subdev` function. Unregistration is
+performed using the :c:func:`v4l2_async_unregister_subdev` call. Subdevices
+registered this way are stored in a global list of subdevices, ready to be
+picked up by bridge drivers.
+
+Bridge drivers in turn have to register a notifier object. This is
+performed using the :c:func:`v4l2_async_notifier_register` call. To
+unregister the notifier the driver has to call
+:c:func:`v4l2_async_notifier_unregister`. The former of the two functions
+takes two arguments: a pointer to struct :c:type:`v4l2_device` and a
+pointer to struct :c:type:`v4l2_async_notifier`.
+
+Before registering the notifier, bridge drivers must do two things:
+first, the notifier must be initialized using the
+:c:func:`v4l2_async_notifier_init`. Second, bridge drivers can then
+begin to form a list of subdevice descriptors that the bridge device
+needs for its operation. Subdevice descriptors are added to the notifier
+using the :c:func:`v4l2_async_notifier_add_subdev` call. This function
+takes two arguments: a pointer to struct :c:type:`v4l2_async_notifier`,
+and a pointer to the subdevice descripter, which is of type struct
+:c:type:`v4l2_async_subdev`.
+
+The V4L2 core will then use these descriptors to match asynchronously
+registered subdevices to them. If a match is detected the ``.bound()``
+notifier callback is called. After all subdevices have been located the
+.complete() callback is called. When a subdevice is removed from the
+system the .unbind() method is called. All three callbacks are optional.
+
+V4L2 sub-device userspace API
+-----------------------------
+
+Beside exposing a kernel API through the :c:type:`v4l2_subdev_ops` structure,
+V4L2 sub-devices can also be controlled directly by userspace applications.
+
+Device nodes named ``v4l-subdev``\ *X* can be created in ``/dev`` to access
+sub-devices directly. If a sub-device supports direct userspace configuration
+it must set the ``V4L2_SUBDEV_FL_HAS_DEVNODE`` flag before being registered.
+
+After registering sub-devices, the :c:type:`v4l2_device` driver can create
+device nodes for all registered sub-devices marked with
+``V4L2_SUBDEV_FL_HAS_DEVNODE`` by calling
+:c:func:`v4l2_device_register_subdev_nodes`. Those device nodes will be
+automatically removed when sub-devices are unregistered.
+
+The device node handles a subset of the V4L2 API.
+
+``VIDIOC_QUERYCTRL``,
+``VIDIOC_QUERYMENU``,
+``VIDIOC_G_CTRL``,
+``VIDIOC_S_CTRL``,
+``VIDIOC_G_EXT_CTRLS``,
+``VIDIOC_S_EXT_CTRLS`` and
+``VIDIOC_TRY_EXT_CTRLS``:
+
+	The controls ioctls are identical to the ones defined in V4L2. They
+	behave identically, with the only exception that they deal only with
+	controls implemented in the sub-device. Depending on the driver, those
+	controls can be also be accessed through one (or several) V4L2 device
+	nodes.
+
+``VIDIOC_DQEVENT``,
+``VIDIOC_SUBSCRIBE_EVENT`` and
+``VIDIOC_UNSUBSCRIBE_EVENT``
+
+	The events ioctls are identical to the ones defined in V4L2. They
+	behave identically, with the only exception that they deal only with
+	events generated by the sub-device. Depending on the driver, those
+	events can also be reported by one (or several) V4L2 device nodes.
+
+	Sub-device drivers that want to use events need to set the
+	``V4L2_SUBDEV_USES_EVENTS`` :c:type:`v4l2_subdev`.flags and initialize
+	:c:type:`v4l2_subdev`.nevents to events queue depth before registering
+	the sub-device. After registration events can be queued as usual on the
+	:c:type:`v4l2_subdev`.devnode device node.
+
+	To properly support events, the ``poll()`` file operation is also
+	implemented.
+
+Private ioctls
+
+	All ioctls not in the above list are passed directly to the sub-device
+	driver through the core::ioctl operation.
+
+
+I2C sub-device drivers
+----------------------
+
+Since these drivers are so common, special helper functions are available to
+ease the use of these drivers (``v4l2-common.h``).
+
+The recommended method of adding :c:type:`v4l2_subdev` support to an I2C driver
+is to embed the :c:type:`v4l2_subdev` struct into the state struct that is
+created for each I2C device instance. Very simple devices have no state
+struct and in that case you can just create a :c:type:`v4l2_subdev` directly.
+
+A typical state struct would look like this (where 'chipname' is replaced by
+the name of the chip):
+
+.. code-block:: c
+
+	struct chipname_state {
+		struct v4l2_subdev sd;
+		...  /* additional state fields */
+	};
+
+Initialize the :c:type:`v4l2_subdev` struct as follows:
+
+.. code-block:: c
+
+	v4l2_i2c_subdev_init(&state->sd, client, subdev_ops);
+
+This function will fill in all the fields of :c:type:`v4l2_subdev` ensure that
+the :c:type:`v4l2_subdev` and i2c_client both point to one another.
+
+You should also add a helper inline function to go from a :c:type:`v4l2_subdev`
+pointer to a chipname_state struct:
+
+.. code-block:: c
+
+	static inline struct chipname_state *to_state(struct v4l2_subdev *sd)
+	{
+		return container_of(sd, struct chipname_state, sd);
+	}
+
+Use this to go from the :c:type:`v4l2_subdev` struct to the ``i2c_client``
+struct:
+
+.. code-block:: c
+
+	struct i2c_client *client = v4l2_get_subdevdata(sd);
+
+And this to go from an ``i2c_client`` to a :c:type:`v4l2_subdev` struct:
+
+.. code-block:: c
+
+	struct v4l2_subdev *sd = i2c_get_clientdata(client);
+
+Make sure to call
+:c:func:`v4l2_device_unregister_subdev`\ (:c:type:`sd <v4l2_subdev>`)
+when the ``remove()`` callback is called. This will unregister the sub-device
+from the bridge driver. It is safe to call this even if the sub-device was
+never registered.
+
+You need to do this because when the bridge driver destroys the i2c adapter
+the ``remove()`` callbacks are called of the i2c devices on that adapter.
+After that the corresponding v4l2_subdev structures are invalid, so they
+have to be unregistered first. Calling
+:c:func:`v4l2_device_unregister_subdev`\ (:c:type:`sd <v4l2_subdev>`)
+from the ``remove()`` callback ensures that this is always done correctly.
+
+
+The bridge driver also has some helper functions it can use:
+
+.. code-block:: c
+
+	struct v4l2_subdev *sd = v4l2_i2c_new_subdev(v4l2_dev, adapter,
+					"module_foo", "chipid", 0x36, NULL);
+
+This loads the given module (can be ``NULL`` if no module needs to be loaded)
+and calls :c:func:`i2c_new_device` with the given ``i2c_adapter`` and
+chip/address arguments. If all goes well, then it registers the subdev with
+the v4l2_device.
+
+You can also use the last argument of :c:func:`v4l2_i2c_new_subdev` to pass
+an array of possible I2C addresses that it should probe. These probe addresses
+are only used if the previous argument is 0. A non-zero argument means that you
+know the exact i2c address so in that case no probing will take place.
+
+Both functions return ``NULL`` if something went wrong.
+
+Note that the chipid you pass to :c:func:`v4l2_i2c_new_subdev` is usually
+the same as the module name. It allows you to specify a chip variant, e.g.
+"saa7114" or "saa7115". In general though the i2c driver autodetects this.
+The use of chipid is something that needs to be looked at more closely at a
+later date. It differs between i2c drivers and as such can be confusing.
+To see which chip variants are supported you can look in the i2c driver code
+for the i2c_device_id table. This lists all the possibilities.
+
+There are one more helper function:
+
+:c:func:`v4l2_i2c_new_subdev_board` uses an :c:type:`i2c_board_info` struct
+which is passed to the i2c driver and replaces the irq, platform_data and addr
+arguments.
+
+If the subdev supports the s_config core ops, then that op is called with
+the irq and platform_data arguments after the subdev was setup.
+
+The :c:func:`v4l2_i2c_new_subdev` function will call
+:c:func:`v4l2_i2c_new_subdev_board`, internally filling a
+:c:type:`i2c_board_info` structure using the ``client_type`` and the
+``addr`` to fill it.
+
+V4L2 sub-device functions and data structures
+---------------------------------------------
+
+.. kernel-doc:: include/media/v4l2-subdev.h
+
+.. kernel-doc:: include/media/v4l2-async.h
diff --git a/Documentation/driver-api/media/v4l2-tuner.rst b/Documentation/driver-api/media/v4l2-tuner.rst
new file mode 100644
index 000000000000..e6caa3321566
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-tuner.rst
@@ -0,0 +1,8 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Tuner functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/tuner.h
+
+.. kernel-doc:: include/media/tuner-types.h
diff --git a/Documentation/driver-api/media/v4l2-tveeprom.rst b/Documentation/driver-api/media/v4l2-tveeprom.rst
new file mode 100644
index 000000000000..43fb391edaba
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-tveeprom.rst
@@ -0,0 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Hauppauge TV EEPROM functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/tveeprom.h
diff --git a/Documentation/driver-api/media/v4l2-videobuf.rst b/Documentation/driver-api/media/v4l2-videobuf.rst
new file mode 100644
index 000000000000..1a7756397b1a
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-videobuf.rst
@@ -0,0 +1,406 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _vb_framework:
+
+Videobuf Framework
+==================
+
+Author: Jonathan Corbet <corbet@lwn.net>
+
+Current as of 2.6.33
+
+.. note::
+
+   The videobuf framework was deprecated in favor of videobuf2. Shouldn't
+   be used on new drivers.
+
+Introduction
+------------
+
+The videobuf layer functions as a sort of glue layer between a V4L2 driver
+and user space.  It handles the allocation and management of buffers for
+the storage of video frames.  There is a set of functions which can be used
+to implement many of the standard POSIX I/O system calls, including read(),
+poll(), and, happily, mmap().  Another set of functions can be used to
+implement the bulk of the V4L2 ioctl() calls related to streaming I/O,
+including buffer allocation, queueing and dequeueing, and streaming
+control.  Using videobuf imposes a few design decisions on the driver
+author, but the payback comes in the form of reduced code in the driver and
+a consistent implementation of the V4L2 user-space API.
+
+Buffer types
+------------
+
+Not all video devices use the same kind of buffers.  In fact, there are (at
+least) three common variations:
+
+ - Buffers which are scattered in both the physical and (kernel) virtual
+   address spaces.  (Almost) all user-space buffers are like this, but it
+   makes great sense to allocate kernel-space buffers this way as well when
+   it is possible.  Unfortunately, it is not always possible; working with
+   this kind of buffer normally requires hardware which can do
+   scatter/gather DMA operations.
+
+ - Buffers which are physically scattered, but which are virtually
+   contiguous; buffers allocated with vmalloc(), in other words.  These
+   buffers are just as hard to use for DMA operations, but they can be
+   useful in situations where DMA is not available but virtually-contiguous
+   buffers are convenient.
+
+ - Buffers which are physically contiguous.  Allocation of this kind of
+   buffer can be unreliable on fragmented systems, but simpler DMA
+   controllers cannot deal with anything else.
+
+Videobuf can work with all three types of buffers, but the driver author
+must pick one at the outset and design the driver around that decision.
+
+[It's worth noting that there's a fourth kind of buffer: "overlay" buffers
+which are located within the system's video memory.  The overlay
+functionality is considered to be deprecated for most use, but it still
+shows up occasionally in system-on-chip drivers where the performance
+benefits merit the use of this technique.  Overlay buffers can be handled
+as a form of scattered buffer, but there are very few implementations in
+the kernel and a description of this technique is currently beyond the
+scope of this document.]
+
+Data structures, callbacks, and initialization
+----------------------------------------------
+
+Depending on which type of buffers are being used, the driver should
+include one of the following files:
+
+.. code-block:: none
+
+    <media/videobuf-dma-sg.h>		/* Physically scattered */
+    <media/videobuf-vmalloc.h>		/* vmalloc() buffers	*/
+    <media/videobuf-dma-contig.h>	/* Physically contiguous */
+
+The driver's data structure describing a V4L2 device should include a
+struct videobuf_queue instance for the management of the buffer queue,
+along with a list_head for the queue of available buffers.  There will also
+need to be an interrupt-safe spinlock which is used to protect (at least)
+the queue.
+
+The next step is to write four simple callbacks to help videobuf deal with
+the management of buffers:
+
+.. code-block:: none
+
+    struct videobuf_queue_ops {
+	int (*buf_setup)(struct videobuf_queue *q,
+			 unsigned int *count, unsigned int *size);
+	int (*buf_prepare)(struct videobuf_queue *q,
+			   struct videobuf_buffer *vb,
+			   enum v4l2_field field);
+	void (*buf_queue)(struct videobuf_queue *q,
+			  struct videobuf_buffer *vb);
+	void (*buf_release)(struct videobuf_queue *q,
+			    struct videobuf_buffer *vb);
+    };
+
+buf_setup() is called early in the I/O process, when streaming is being
+initiated; its purpose is to tell videobuf about the I/O stream.  The count
+parameter will be a suggested number of buffers to use; the driver should
+check it for rationality and adjust it if need be.  As a practical rule, a
+minimum of two buffers are needed for proper streaming, and there is
+usually a maximum (which cannot exceed 32) which makes sense for each
+device.  The size parameter should be set to the expected (maximum) size
+for each frame of data.
+
+Each buffer (in the form of a struct videobuf_buffer pointer) will be
+passed to buf_prepare(), which should set the buffer's size, width, height,
+and field fields properly.  If the buffer's state field is
+VIDEOBUF_NEEDS_INIT, the driver should pass it to:
+
+.. code-block:: none
+
+    int videobuf_iolock(struct videobuf_queue* q, struct videobuf_buffer *vb,
+			struct v4l2_framebuffer *fbuf);
+
+Among other things, this call will usually allocate memory for the buffer.
+Finally, the buf_prepare() function should set the buffer's state to
+VIDEOBUF_PREPARED.
+
+When a buffer is queued for I/O, it is passed to buf_queue(), which should
+put it onto the driver's list of available buffers and set its state to
+VIDEOBUF_QUEUED.  Note that this function is called with the queue spinlock
+held; if it tries to acquire it as well things will come to a screeching
+halt.  Yes, this is the voice of experience.  Note also that videobuf may
+wait on the first buffer in the queue; placing other buffers in front of it
+could again gum up the works.  So use list_add_tail() to enqueue buffers.
+
+Finally, buf_release() is called when a buffer is no longer intended to be
+used.  The driver should ensure that there is no I/O active on the buffer,
+then pass it to the appropriate free routine(s):
+
+.. code-block:: none
+
+    /* Scatter/gather drivers */
+    int videobuf_dma_unmap(struct videobuf_queue *q,
+			   struct videobuf_dmabuf *dma);
+    int videobuf_dma_free(struct videobuf_dmabuf *dma);
+
+    /* vmalloc drivers */
+    void videobuf_vmalloc_free (struct videobuf_buffer *buf);
+
+    /* Contiguous drivers */
+    void videobuf_dma_contig_free(struct videobuf_queue *q,
+				  struct videobuf_buffer *buf);
+
+One way to ensure that a buffer is no longer under I/O is to pass it to:
+
+.. code-block:: none
+
+    int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr);
+
+Here, vb is the buffer, non_blocking indicates whether non-blocking I/O
+should be used (it should be zero in the buf_release() case), and intr
+controls whether an interruptible wait is used.
+
+File operations
+---------------
+
+At this point, much of the work is done; much of the rest is slipping
+videobuf calls into the implementation of the other driver callbacks.  The
+first step is in the open() function, which must initialize the
+videobuf queue.  The function to use depends on the type of buffer used:
+
+.. code-block:: none
+
+    void videobuf_queue_sg_init(struct videobuf_queue *q,
+				struct videobuf_queue_ops *ops,
+				struct device *dev,
+				spinlock_t *irqlock,
+				enum v4l2_buf_type type,
+				enum v4l2_field field,
+				unsigned int msize,
+				void *priv);
+
+    void videobuf_queue_vmalloc_init(struct videobuf_queue *q,
+				struct videobuf_queue_ops *ops,
+				struct device *dev,
+				spinlock_t *irqlock,
+				enum v4l2_buf_type type,
+				enum v4l2_field field,
+				unsigned int msize,
+				void *priv);
+
+    void videobuf_queue_dma_contig_init(struct videobuf_queue *q,
+				       struct videobuf_queue_ops *ops,
+				       struct device *dev,
+				       spinlock_t *irqlock,
+				       enum v4l2_buf_type type,
+				       enum v4l2_field field,
+				       unsigned int msize,
+				       void *priv);
+
+In each case, the parameters are the same: q is the queue structure for the
+device, ops is the set of callbacks as described above, dev is the device
+structure for this video device, irqlock is an interrupt-safe spinlock to
+protect access to the data structures, type is the buffer type used by the
+device (cameras will use V4L2_BUF_TYPE_VIDEO_CAPTURE, for example), field
+describes which field is being captured (often V4L2_FIELD_NONE for
+progressive devices), msize is the size of any containing structure used
+around struct videobuf_buffer, and priv is a private data pointer which
+shows up in the priv_data field of struct videobuf_queue.  Note that these
+are void functions which, evidently, are immune to failure.
+
+V4L2 capture drivers can be written to support either of two APIs: the
+read() system call and the rather more complicated streaming mechanism.  As
+a general rule, it is necessary to support both to ensure that all
+applications have a chance of working with the device.  Videobuf makes it
+easy to do that with the same code.  To implement read(), the driver need
+only make a call to one of:
+
+.. code-block:: none
+
+    ssize_t videobuf_read_one(struct videobuf_queue *q,
+			      char __user *data, size_t count,
+			      loff_t *ppos, int nonblocking);
+
+    ssize_t videobuf_read_stream(struct videobuf_queue *q,
+				 char __user *data, size_t count,
+				 loff_t *ppos, int vbihack, int nonblocking);
+
+Either one of these functions will read frame data into data, returning the
+amount actually read; the difference is that videobuf_read_one() will only
+read a single frame, while videobuf_read_stream() will read multiple frames
+if they are needed to satisfy the count requested by the application.  A
+typical driver read() implementation will start the capture engine, call
+one of the above functions, then stop the engine before returning (though a
+smarter implementation might leave the engine running for a little while in
+anticipation of another read() call happening in the near future).
+
+The poll() function can usually be implemented with a direct call to:
+
+.. code-block:: none
+
+    unsigned int videobuf_poll_stream(struct file *file,
+				      struct videobuf_queue *q,
+				      poll_table *wait);
+
+Note that the actual wait queue eventually used will be the one associated
+with the first available buffer.
+
+When streaming I/O is done to kernel-space buffers, the driver must support
+the mmap() system call to enable user space to access the data.  In many
+V4L2 drivers, the often-complex mmap() implementation simplifies to a
+single call to:
+
+.. code-block:: none
+
+    int videobuf_mmap_mapper(struct videobuf_queue *q,
+			     struct vm_area_struct *vma);
+
+Everything else is handled by the videobuf code.
+
+The release() function requires two separate videobuf calls:
+
+.. code-block:: none
+
+    void videobuf_stop(struct videobuf_queue *q);
+    int videobuf_mmap_free(struct videobuf_queue *q);
+
+The call to videobuf_stop() terminates any I/O in progress - though it is
+still up to the driver to stop the capture engine.  The call to
+videobuf_mmap_free() will ensure that all buffers have been unmapped; if
+so, they will all be passed to the buf_release() callback.  If buffers
+remain mapped, videobuf_mmap_free() returns an error code instead.  The
+purpose is clearly to cause the closing of the file descriptor to fail if
+buffers are still mapped, but every driver in the 2.6.32 kernel cheerfully
+ignores its return value.
+
+ioctl() operations
+------------------
+
+The V4L2 API includes a very long list of driver callbacks to respond to
+the many ioctl() commands made available to user space.  A number of these
+- those associated with streaming I/O - turn almost directly into videobuf
+calls.  The relevant helper functions are:
+
+.. code-block:: none
+
+    int videobuf_reqbufs(struct videobuf_queue *q,
+			 struct v4l2_requestbuffers *req);
+    int videobuf_querybuf(struct videobuf_queue *q, struct v4l2_buffer *b);
+    int videobuf_qbuf(struct videobuf_queue *q, struct v4l2_buffer *b);
+    int videobuf_dqbuf(struct videobuf_queue *q, struct v4l2_buffer *b,
+		       int nonblocking);
+    int videobuf_streamon(struct videobuf_queue *q);
+    int videobuf_streamoff(struct videobuf_queue *q);
+
+So, for example, a VIDIOC_REQBUFS call turns into a call to the driver's
+vidioc_reqbufs() callback which, in turn, usually only needs to locate the
+proper struct videobuf_queue pointer and pass it to videobuf_reqbufs().
+These support functions can replace a great deal of buffer management
+boilerplate in a lot of V4L2 drivers.
+
+The vidioc_streamon() and vidioc_streamoff() functions will be a bit more
+complex, of course, since they will also need to deal with starting and
+stopping the capture engine.
+
+Buffer allocation
+-----------------
+
+Thus far, we have talked about buffers, but have not looked at how they are
+allocated.  The scatter/gather case is the most complex on this front.  For
+allocation, the driver can leave buffer allocation entirely up to the
+videobuf layer; in this case, buffers will be allocated as anonymous
+user-space pages and will be very scattered indeed.  If the application is
+using user-space buffers, no allocation is needed; the videobuf layer will
+take care of calling get_user_pages() and filling in the scatterlist array.
+
+If the driver needs to do its own memory allocation, it should be done in
+the vidioc_reqbufs() function, *after* calling videobuf_reqbufs().  The
+first step is a call to:
+
+.. code-block:: none
+
+    struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
+
+The returned videobuf_dmabuf structure (defined in
+<media/videobuf-dma-sg.h>) includes a couple of relevant fields:
+
+.. code-block:: none
+
+    struct scatterlist  *sglist;
+    int                 sglen;
+
+The driver must allocate an appropriately-sized scatterlist array and
+populate it with pointers to the pieces of the allocated buffer; sglen
+should be set to the length of the array.
+
+Drivers using the vmalloc() method need not (and cannot) concern themselves
+with buffer allocation at all; videobuf will handle those details.  The
+same is normally true of contiguous-DMA drivers as well; videobuf will
+allocate the buffers (with dma_alloc_coherent()) when it sees fit.  That
+means that these drivers may be trying to do high-order allocations at any
+time, an operation which is not always guaranteed to work.  Some drivers
+play tricks by allocating DMA space at system boot time; videobuf does not
+currently play well with those drivers.
+
+As of 2.6.31, contiguous-DMA drivers can work with a user-supplied buffer,
+as long as that buffer is physically contiguous.  Normal user-space
+allocations will not meet that criterion, but buffers obtained from other
+kernel drivers, or those contained within huge pages, will work with these
+drivers.
+
+Filling the buffers
+-------------------
+
+The final part of a videobuf implementation has no direct callback - it's
+the portion of the code which actually puts frame data into the buffers,
+usually in response to interrupts from the device.  For all types of
+drivers, this process works approximately as follows:
+
+ - Obtain the next available buffer and make sure that somebody is actually
+   waiting for it.
+
+ - Get a pointer to the memory and put video data there.
+
+ - Mark the buffer as done and wake up the process waiting for it.
+
+Step (1) above is done by looking at the driver-managed list_head structure
+- the one which is filled in the buf_queue() callback.  Because starting
+the engine and enqueueing buffers are done in separate steps, it's possible
+for the engine to be running without any buffers available - in the
+vmalloc() case especially.  So the driver should be prepared for the list
+to be empty.  It is equally possible that nobody is yet interested in the
+buffer; the driver should not remove it from the list or fill it until a
+process is waiting on it.  That test can be done by examining the buffer's
+done field (a wait_queue_head_t structure) with waitqueue_active().
+
+A buffer's state should be set to VIDEOBUF_ACTIVE before being mapped for
+DMA; that ensures that the videobuf layer will not try to do anything with
+it while the device is transferring data.
+
+For scatter/gather drivers, the needed memory pointers will be found in the
+scatterlist structure described above.  Drivers using the vmalloc() method
+can get a memory pointer with:
+
+.. code-block:: none
+
+    void *videobuf_to_vmalloc(struct videobuf_buffer *buf);
+
+For contiguous DMA drivers, the function to use is:
+
+.. code-block:: none
+
+    dma_addr_t videobuf_to_dma_contig(struct videobuf_buffer *buf);
+
+The contiguous DMA API goes out of its way to hide the kernel-space address
+of the DMA buffer from drivers.
+
+The final step is to set the size field of the relevant videobuf_buffer
+structure to the actual size of the captured image, set state to
+VIDEOBUF_DONE, then call wake_up() on the done queue.  At this point, the
+buffer is owned by the videobuf layer and the driver should not touch it
+again.
+
+Developers who are interested in more information can go into the relevant
+header files; there are a few low-level functions declared there which have
+not been talked about here.  Also worthwhile is the vivi driver
+(drivers/media/platform/vivi.c), which is maintained as an example of how V4L2
+drivers should be written.  Vivi only uses the vmalloc() API, but it's good
+enough to get started with.  Note also that all of these calls are exported
+GPL-only, so they will not be available to non-GPL kernel modules.
diff --git a/Documentation/driver-api/media/v4l2-videobuf2.rst b/Documentation/driver-api/media/v4l2-videobuf2.rst
new file mode 100644
index 000000000000..1044f64ff168
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-videobuf2.rst
@@ -0,0 +1,12 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _vb2_framework:
+
+V4L2 videobuf2 functions and data structures
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. kernel-doc:: include/media/videobuf2-core.h
+
+.. kernel-doc:: include/media/videobuf2-v4l2.h
+
+.. kernel-doc:: include/media/videobuf2-memops.h