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authorSimon Glass2020-04-26 09:19:45 -0600
committerBin Meng2020-04-30 17:16:12 +0800
commitfa04cef6443eab008b99f6439ec8a3b9939253b4 (patch)
tree157b261f5b1a526c3e080fd3b353fbc947d51b2b
parent43a1230adfbf44fd2a8b77aa73528a1d3e604de6 (diff)
acpi: Add a binding for ACPI settings in the device tree
Devices need to report various identifiers in the ACPI tables. Rather than hard-coding these in drivers it is typically better to put them in the device tree. Add a binding file to describe this. Signed-off-by: Simon Glass <sjg@chromium.org>
-rw-r--r--doc/device-tree-bindings/device.txt36
1 files changed, 36 insertions, 0 deletions
diff --git a/doc/device-tree-bindings/device.txt b/doc/device-tree-bindings/device.txt
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+Devices
+=======
+
+Device bindings are described by their own individual binding files.
+
+U-Boot provides for some optional properties which are documented here. See
+also hid-over-i2c.txt which describes HID devices. See also
+Documentation/firmware-guide/acpi/enumeration.rst in the Linux kernel for
+the acpi,compatible property.
+
+ - acpi,has-power-resource : (boolean) true if this device has a power resource.
+ This causes an ACPI PowerResource to be written containing the properties
+ provided by this binding, to describe how to handle powering the device up
+ and down using GPIOs
+ - acpi,compatible : compatible string to report
+ - acpi,ddn : Contains the string to use as the _DDN (DOS (Disk Operating
+ System) Device Name)
+ - acpi,hid : Contains the string to use as the HID (Hardware ID)
+ identifier _HID
+ - acpi,uid : _UID value for device
+ - linux,probed : Tells U-Boot to add 'linux,probed' to the ACPI tables so that
+ Linux will only load the driver if the device can be detected (e.g. on I2C
+ bus). Note that this is an out-of-tree Linux feature.
+
+
+Example
+-------
+
+elan_touchscreen: elan-touchscreen@10 {
+ compatible = "i2c-chip";
+ reg = <0x10>;
+ acpi,hid = "ELAN0001";
+ acpi,ddn = "ELAN Touchscreen";
+ interrupts-extended = <&acpi_gpe GPIO_21_IRQ IRQ_TYPE_EDGE_FALLING>;
+ linux,probed;
+};