[PATCH v3] rpmsg: ctrl: Introduce new RPMSG_CREATE/RELEASE_DEV_IOCTL controls

[Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>]

Allow the user space application to create and release an rpmsg device
by adding RPMSG_CREATE_DEV_IOCTL and RPMSG_RELEASE_DEV_IOCTL ioctrls to
the /dev/rpmsg_ctrl interface

The RPMSG_CREATE_DEV_IOCTL Ioctl can be used to instantiate a local rpmsg
device.
Depending on the back-end implementation, the associated rpmsg driver is
probed and a NS announcement can be sent to the remote processor.

The RPMSG_RELEASE_DEV_IOCTL allows the user application to release a
rpmsg device created either by the remote processor or with the
RPMSG_CREATE_DEV_IOCTL call.
Depending on the back-end implementation, the associated rpmsg driver is
removed and a NS destroy rpmsg can be sent to the remote processor.

Suggested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
update from V2
- add Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
- rebased on kernel V.14-rc1 + 
  series V5 Restructure the rpmsg char to decorrelate the control part [1]


[1] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=514017

---
 drivers/rpmsg/rpmsg_ctrl.c | 37 +++++++++++++++++++++++++++++++++----
 include/uapi/linux/rpmsg.h | 10 ++++++++++
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c
index eeb1708548c1..cb19e32d05e1 100644
--- a/drivers/rpmsg/rpmsg_ctrl.c
+++ b/drivers/rpmsg/rpmsg_ctrl.c
@@ -23,6 +23,7 @@
 #include <uapi/linux/rpmsg.h>
 
 #include "rpmsg_char.h"
+#include "rpmsg_internal.h"
 
 static dev_t rpmsg_major;
 
@@ -37,11 +38,13 @@ static DEFINE_IDA(rpmsg_minor_ida);
  * @rpdev:	underlaying rpmsg device
  * @cdev:	cdev for the ctrl device
  * @dev:	device for the ctrl device
+ * @ctrl_lock:	serialize the ioctrls.
  */
 struct rpmsg_ctrldev {
 	struct rpmsg_device *rpdev;
 	struct cdev cdev;
 	struct device dev;
+	struct mutex ctrl_lock;
 };
 
 static int rpmsg_ctrldev_open(struct inode *inode, struct file *filp)
@@ -70,9 +73,8 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
 	void __user *argp = (void __user *)arg;
 	struct rpmsg_endpoint_info eptinfo;
 	struct rpmsg_channel_info chinfo;
-
-	if (cmd != RPMSG_CREATE_EPT_IOCTL)
-		return -EINVAL;
+	struct rpmsg_device *rpdev;
+	int ret = 0;
 
 	if (copy_from_user(&eptinfo, argp, sizeof(eptinfo)))
 		return -EFAULT;
@@ -82,7 +84,33 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
 	chinfo.src = eptinfo.src;
 	chinfo.dst = eptinfo.dst;
 
-	return rpmsg_chrdev_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo);
+	mutex_lock(&ctrldev->ctrl_lock);
+	switch (cmd) {
+	case RPMSG_CREATE_EPT_IOCTL:
+		ret = rpmsg_chrdev_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo);
+		break;
+
+	case RPMSG_CREATE_DEV_IOCTL:
+		rpdev = rpmsg_create_channel(ctrldev->rpdev, &chinfo);
+		if (!rpdev) {
+			dev_err(&ctrldev->dev, "failed to create %s channel\n", chinfo.name);
+			ret = -ENXIO;
+		}
+		break;
+
+	case RPMSG_RELEASE_DEV_IOCTL:
+		ret = rpmsg_release_channel(ctrldev->rpdev, &chinfo);
+		if (ret)
+			dev_err(&ctrldev->dev, "failed to release %s channel (%d)\n",
+				chinfo.name, ret);
+		break;
+
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&ctrldev->ctrl_lock);
+
+	return ret;
 };
 
 static const struct file_operations rpmsg_ctrldev_fops = {
@@ -119,6 +147,7 @@ static int rpmsg_ctrldev_probe(struct rpmsg_device *rpdev)
 	device_initialize(dev);
 	dev->parent = &rpdev->dev;
 
+	mutex_init(&ctrldev->ctrl_lock);
 	cdev_init(&ctrldev->cdev, &rpmsg_ctrldev_fops);
 	ctrldev->cdev.owner = THIS_MODULE;
 
diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
index f5ca8740f3fb..1637e68177d9 100644
--- a/include/uapi/linux/rpmsg.h
+++ b/include/uapi/linux/rpmsg.h
@@ -33,4 +33,14 @@ struct rpmsg_endpoint_info {
  */
 #define RPMSG_DESTROY_EPT_IOCTL	_IO(0xb5, 0x2)
 
+/**
+ * Instantiate a new local rpmsg service device.
+ */
+#define RPMSG_CREATE_DEV_IOCTL	_IOW(0xb5, 0x3, struct rpmsg_endpoint_info)
+
+/**
+ * Release a local rpmsg device.
+ */
+#define RPMSG_RELEASE_DEV_IOCTL	_IOW(0xb5, 0x4, struct rpmsg_endpoint_info)
+
 #endif
-- 
2.17.1