Merge branch 'RPMSG-WWAN-CTRL-driver'

Stephan Gerhold says:

====================
net: wwan: Add RPMSG WWAN CTRL driver

This patch series adds a WWAN "control" driver for the remote processor
messaging (rpmsg) subsystem. This subsystem allows communicating with
an integrated modem DSP on many Qualcomm SoCs, e.g. MSM8916 or MSM8974.

The driver is a fairly simple glue layer between WWAN and RPMSG
and is mostly based on the existing mhi_wwan_ctrl.c and rpmsg_char.c.

For more information, see commit message in PATCH 2/3.

I already posted a RFC for this a while ago:
https://lore.kernel.org/linux-arm-msm/YLfL9Q+4860uqS8f@gerhold.net/
and now I'm looking for some feedback for the actual changes. :)

Changes in v3:
  - PATCH 2/3: Clarify commit message
  - PATCH 3/3: Fix build error for cdc-wdm.c, use extra tx_blocking() op instead
v2: https://lore.kernel.org/netdev/20210618075243.42046-1-stephan@gerhold.net/

Changes in v2: Only in PATCH 3/3
  - Fix EPOLLOUT being always set even if poll op is defined
  - Rename poll() op -> tx_poll() since it should be only used for TX
v1: https://lore.kernel.org/netdev/20210615133229.213064-1-stephan@gerhold.net/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

8 files changed, 219 insertions, 7 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 183cc61e2dc0..fbf792962d7b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15587,6 +15587,13 @@ F:	include/linux/rpmsg/
 F:	include/uapi/linux/rpmsg.h
 F:	samples/rpmsg/
 
+REMOTE PROCESSOR MESSAGING (RPMSG) WWAN CONTROL DRIVER
+M:	Stephan Gerhold <stephan@gerhold.net>
+L:	netdev@vger.kernel.org
+L:	linux-remoteproc@vger.kernel.org
+S:	Maintained
+F:	drivers/net/wwan/rpmsg_wwan_ctrl.c
+
 RENESAS CLOCK DRIVERS
 M:	Geert Uytterhoeven <geert+renesas@glider.be>
 L:	linux-renesas-soc@vger.kernel.org
diff --git a/drivers/net/wwan/Kconfig b/drivers/net/wwan/Kconfig
index 249b3f1ed62b..de9384326bc8 100644
--- a/drivers/net/wwan/Kconfig
+++ b/drivers/net/wwan/Kconfig
@@ -38,6 +38,24 @@ config MHI_WWAN_CTRL
 	  To compile this driver as a module, choose M here: the module will be
 	  called mhi_wwan_ctrl.
 
+config RPMSG_WWAN_CTRL
+	tristate "RPMSG WWAN control driver"
+	depends on RPMSG
+	help
+	  RPMSG WWAN CTRL allows modems available via RPMSG channels to expose
+	  different modem protocols/ports to userspace, including AT and QMI.
+	  These protocols can be accessed directly from userspace
+	  (e.g. AT commands) or via libraries/tools (e.g. libqmi, libqcdm...).
+
+	  This is mainly used for modems integrated into many Qualcomm SoCs,
+	  e.g. for AT and QMI on Qualcomm MSM8916 or MSM8974. Note that many
+	  newer Qualcomm SoCs (e.g. SDM845) still provide an AT port through
+	  this driver but the QMI messages can only be sent through
+	  QRTR network sockets (CONFIG_QRTR).
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called rpmsg_wwan_ctrl.
+
 config IOSM
 	tristate "IOSM Driver for Intel M.2 WWAN Device"
 	depends on INTEL_IOMMU
diff --git a/drivers/net/wwan/Makefile b/drivers/net/wwan/Makefile
index 83dd3482ffc3..d90ac33abaef 100644
--- a/drivers/net/wwan/Makefile
+++ b/drivers/net/wwan/Makefile
@@ -9,4 +9,5 @@ wwan-objs += wwan_core.o
 obj-$(CONFIG_WWAN_HWSIM) += wwan_hwsim.o
 
 obj-$(CONFIG_MHI_WWAN_CTRL) += mhi_wwan_ctrl.o
+obj-$(CONFIG_RPMSG_WWAN_CTRL) += rpmsg_wwan_ctrl.o
 obj-$(CONFIG_IOSM) += iosm/
diff --git a/drivers/net/wwan/rpmsg_wwan_ctrl.c b/drivers/net/wwan/rpmsg_wwan_ctrl.c
new file mode 100644
index 000000000000..31c24420ab2e
--- /dev/null
+++ b/drivers/net/wwan/rpmsg_wwan_ctrl.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2021, Stephan Gerhold <stephan@gerhold.net> */
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rpmsg.h>
+#include <linux/wwan.h>
+
+struct rpmsg_wwan_dev {
+	/* Lower level is a rpmsg dev, upper level is a wwan port */
+	struct rpmsg_device *rpdev;
+	struct wwan_port *wwan_port;
+	struct rpmsg_endpoint *ept;
+};
+
+static int rpmsg_wwan_ctrl_callback(struct rpmsg_device *rpdev,
+				    void *buf, int len, void *priv, u32 src)
+{
+	struct rpmsg_wwan_dev *rpwwan = priv;
+	struct sk_buff *skb;
+
+	skb = alloc_skb(len, GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	skb_put_data(skb, buf, len);
+	wwan_port_rx(rpwwan->wwan_port, skb);
+	return 0;
+}
+
+static int rpmsg_wwan_ctrl_start(struct wwan_port *port)
+{
+	struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);
+	struct rpmsg_channel_info chinfo = {
+		.src = rpwwan->rpdev->src,
+		.dst = RPMSG_ADDR_ANY,
+	};
+
+	strncpy(chinfo.name, rpwwan->rpdev->id.name, RPMSG_NAME_SIZE);
+	rpwwan->ept = rpmsg_create_ept(rpwwan->rpdev, rpmsg_wwan_ctrl_callback,
+				       rpwwan, chinfo);
+	if (!rpwwan->ept)
+		return -EREMOTEIO;
+
+	return 0;
+}
+
+static void rpmsg_wwan_ctrl_stop(struct wwan_port *port)
+{
+	struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);
+
+	rpmsg_destroy_ept(rpwwan->ept);
+	rpwwan->ept = NULL;
+}
+
+static int rpmsg_wwan_ctrl_tx(struct wwan_port *port, struct sk_buff *skb)
+{
+	struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);
+	int ret;
+
+	ret = rpmsg_trysend(rpwwan->ept, skb->data, skb->len);
+	if (ret)
+		return ret;
+
+	consume_skb(skb);
+	return 0;
+}
+
+static int rpmsg_wwan_ctrl_tx_blocking(struct wwan_port *port, struct sk_buff *skb)
+{
+	struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);
+	int ret;
+
+	ret = rpmsg_send(rpwwan->ept, skb->data, skb->len);
+	if (ret)
+		return ret;
+
+	consume_skb(skb);
+	return 0;
+}
+
+static __poll_t rpmsg_wwan_ctrl_tx_poll(struct wwan_port *port,
+					struct file *filp, poll_table *wait)
+{
+	struct rpmsg_wwan_dev *rpwwan = wwan_port_get_drvdata(port);
+
+	return rpmsg_poll(rpwwan->ept, filp, wait);
+}
+
+static const struct wwan_port_ops rpmsg_wwan_pops = {
+	.start = rpmsg_wwan_ctrl_start,
+	.stop = rpmsg_wwan_ctrl_stop,
+	.tx = rpmsg_wwan_ctrl_tx,
+	.tx_blocking = rpmsg_wwan_ctrl_tx_blocking,
+	.tx_poll = rpmsg_wwan_ctrl_tx_poll,
+};
+
+static struct device *rpmsg_wwan_find_parent(struct device *dev)
+{
+	/* Select first platform device as parent for the WWAN ports.
+	 * On Qualcomm platforms this is usually the platform device that
+	 * represents the modem remote processor. This might need to be
+	 * adjusted when adding device IDs for other platforms.
+	 */
+	for (dev = dev->parent; dev; dev = dev->parent) {
+		if (dev_is_platform(dev))
+			return dev;
+	}
+	return NULL;
+}
+
+static int rpmsg_wwan_ctrl_probe(struct rpmsg_device *rpdev)
+{
+	struct rpmsg_wwan_dev *rpwwan;
+	struct wwan_port *port;
+	struct device *parent;
+
+	parent = rpmsg_wwan_find_parent(&rpdev->dev);
+	if (!parent)
+		return -ENODEV;
+
+	rpwwan = devm_kzalloc(&rpdev->dev, sizeof(*rpwwan), GFP_KERNEL);
+	if (!rpwwan)
+		return -ENOMEM;
+
+	rpwwan->rpdev = rpdev;
+	dev_set_drvdata(&rpdev->dev, rpwwan);
+
+	/* Register as a wwan port, id.driver_data contains wwan port type */
+	port = wwan_create_port(parent, rpdev->id.driver_data,
+				&rpmsg_wwan_pops, rpwwan);
+	if (IS_ERR(port))
+		return PTR_ERR(port);
+
+	rpwwan->wwan_port = port;
+
+	return 0;
+};
+
+static void rpmsg_wwan_ctrl_remove(struct rpmsg_device *rpdev)
+{
+	struct rpmsg_wwan_dev *rpwwan = dev_get_drvdata(&rpdev->dev);
+
+	wwan_remove_port(rpwwan->wwan_port);
+}
+
+static const struct rpmsg_device_id rpmsg_wwan_ctrl_id_table[] = {
+	/* RPMSG channels for Qualcomm SoCs with integrated modem */
+	{ .name = "DATA5_CNTL", .driver_data = WWAN_PORT_QMI },
+	{ .name = "DATA4", .driver_data = WWAN_PORT_AT },
+	{},
+};
+MODULE_DEVICE_TABLE(rpmsg, rpmsg_wwan_ctrl_id_table);
+
+static struct rpmsg_driver rpmsg_wwan_ctrl_driver = {
+	.drv.name = "rpmsg_wwan_ctrl",
+	.id_table = rpmsg_wwan_ctrl_id_table,
+	.probe = rpmsg_wwan_ctrl_probe,
+	.remove = rpmsg_wwan_ctrl_remove,
+};
+module_rpmsg_driver(rpmsg_wwan_ctrl_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("RPMSG WWAN CTRL Driver");
+MODULE_AUTHOR("Stephan Gerhold <stephan@gerhold.net>");
diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 7e728042fc41..165afec1dbd1 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -500,7 +500,8 @@ static void wwan_port_op_stop(struct wwan_port *port)
 	mutex_unlock(&port->ops_lock);
 }
 
-static int wwan_port_op_tx(struct wwan_port *port, struct sk_buff *skb)
+static int wwan_port_op_tx(struct wwan_port *port, struct sk_buff *skb,
+			   bool nonblock)
 {
 	int ret;
 
@@ -510,7 +511,10 @@ static int wwan_port_op_tx(struct wwan_port *port, struct sk_buff *skb)
 		goto out_unlock;
 	}
 
-	ret = port->ops->tx(port, skb);
+	if (nonblock || !port->ops->tx_blocking)
+		ret = port->ops->tx(port, skb);
+	else
+		ret = port->ops->tx_blocking(port, skb);
 
 out_unlock:
 	mutex_unlock(&port->ops_lock);
@@ -637,7 +641,7 @@ static ssize_t wwan_port_fops_write(struct file *filp, const char __user *buf,
 		return -EFAULT;
 	}
 
-	ret = wwan_port_op_tx(port, skb);
+	ret = wwan_port_op_tx(port, skb, !!(filp->f_flags & O_NONBLOCK));
 	if (ret) {
 		kfree_skb(skb);
 		return ret;
@@ -653,12 +657,16 @@ static __poll_t wwan_port_fops_poll(struct file *filp, poll_table *wait)
 
 	poll_wait(filp, &port->waitqueue, wait);
 
-	if (!is_write_blocked(port))
+	mutex_lock(&port->ops_lock);
+	if (port->ops && port->ops->tx_poll)
+		mask |= port->ops->tx_poll(port, filp, wait);
+	else if (!is_write_blocked(port))
 		mask |= EPOLLOUT | EPOLLWRNORM;
 	if (!is_read_blocked(port))
 		mask |= EPOLLIN | EPOLLRDNORM;
 	if (!port->ops)
 		mask |= EPOLLHUP | EPOLLERR;
+	mutex_unlock(&port->ops_lock);
 
 	return mask;
 }
diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index e5daee4f9373..c1404d3dae2c 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -459,8 +459,10 @@ static int rpmsg_dev_match(struct device *dev, struct device_driver *drv)
 
 	if (ids)
 		for (i = 0; ids[i].name[0]; i++)
-			if (rpmsg_id_match(rpdev, &ids[i]))
+			if (rpmsg_id_match(rpdev, &ids[i])) {
+				rpdev->id.driver_data = ids[i].driver_data;
 				return 1;
+			}
 
 	return of_driver_match_device(dev, drv);
 }
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 7d45b5f989b0..8e291cfdaf06 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -447,6 +447,7 @@ struct hv_vmbus_device_id {
 
 struct rpmsg_device_id {
 	char name[RPMSG_NAME_SIZE];
+	kernel_ulong_t driver_data;
 };
 
 /* i2c */
diff --git a/include/linux/wwan.h b/include/linux/wwan.h
index 430a3a0817de..34222230360c 100644
--- a/include/linux/wwan.h
+++ b/include/linux/wwan.h
@@ -6,6 +6,7 @@
 
 #include <linux/device.h>
 #include <linux/kernel.h>
+#include <linux/poll.h>
 #include <linux/skbuff.h>
 #include <linux/netlink.h>
 
@@ -40,15 +41,23 @@ struct wwan_port;
 /** struct wwan_port_ops - The WWAN port operations
  * @start: The routine for starting the WWAN port device.
  * @stop: The routine for stopping the WWAN port device.
- * @tx: The routine that sends WWAN port protocol data to the device.
+ * @tx: Non-blocking routine that sends WWAN port protocol data to the device.
+ * @tx_blocking: Optional blocking routine that sends WWAN port protocol data
+ *               to the device.
+ * @tx_poll: Optional routine that sets additional TX poll flags.
  *
  * The wwan_port_ops structure contains a list of low-level operations
- * that control a WWAN port device. All functions are mandatory.
+ * that control a WWAN port device. All functions are mandatory unless specified.
  */
 struct wwan_port_ops {
 	int (*start)(struct wwan_port *port);
 	void (*stop)(struct wwan_port *port);
 	int (*tx)(struct wwan_port *port, struct sk_buff *skb);
+
+	/* Optional operations */
+	int (*tx_blocking)(struct wwan_port *port, struct sk_buff *skb);
+	__poll_t (*tx_poll)(struct wwan_port *port, struct file *filp,
+			    poll_table *wait);
 };
 
 /**