[PATCH v5 3/3] rpmsg: ctrl: Introduce RPMSG_CREATE_EPT_FD_IOCTL uAPI

[Dawei Li <dawei.li@linux.dev>]

Implement RPMSG_CREATE_EPT_FD_IOCTL, new uAPI for rpmsg ctrl, which
shares most of operations of RPMSG_CREATE_EPT_IOCTL except that it
returns fd representing eptdev to userspace directly.

Possible calling procedures for userspace are:
- fd = open("/dev/rpmsg_ctrlX")
- ioctl(fd, RPMSG_CREATE_EPT_FD_IOCTL, &info);
- fd_ep = info.fd
- operations on fd_ep(write, read, poll ioctl)
- ioctl(fd_ep, RPMSG_DESTROY_EPT_IOCTL)
- close(fd_ep)
- close(fd)

Signed-off-by: Dawei Li <dawei.li@linux.dev>
---
 drivers/rpmsg/rpmsg_ctrl.c | 35 ++++++++++++++++++++++++++++-------
 include/uapi/linux/rpmsg.h | 27 ++++++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 8 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c
index 28f57945ccd9..efb207506e5c 100644
--- a/drivers/rpmsg/rpmsg_ctrl.c
+++ b/drivers/rpmsg/rpmsg_ctrl.c
@@ -75,19 +75,30 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
 				unsigned long arg)
 {
 	struct rpmsg_ctrldev *ctrldev = fp->private_data;
+	struct rpmsg_endpoint_fd_info ept_fd_info;
 	void __user *argp = (void __user *)arg;
 	struct rpmsg_endpoint_info eptinfo;
 	struct rpmsg_channel_info chinfo;
 	struct rpmsg_device *rpdev;
 	int ret = 0;
 
-	if (copy_from_user(&eptinfo, argp, sizeof(eptinfo)))
-		return -EFAULT;
-
-	memcpy(chinfo.name, eptinfo.name, RPMSG_NAME_SIZE);
-	chinfo.name[RPMSG_NAME_SIZE - 1] = '\0';
-	chinfo.src = eptinfo.src;
-	chinfo.dst = eptinfo.dst;
+	if (cmd == RPMSG_CREATE_EPT_FD_IOCTL) {
+		if (copy_from_user(&ept_fd_info, argp, sizeof(ept_fd_info)))
+			return -EFAULT;
+
+		memcpy(chinfo.name, ept_fd_info.name, RPMSG_NAME_SIZE);
+		chinfo.name[RPMSG_NAME_SIZE - 1] = '\0';
+		chinfo.src = ept_fd_info.src;
+		chinfo.dst = ept_fd_info.dst;
+	} else {
+		if (copy_from_user(&eptinfo, argp, sizeof(eptinfo)))
+			return -EFAULT;
+
+		memcpy(chinfo.name, eptinfo.name, RPMSG_NAME_SIZE);
+		chinfo.name[RPMSG_NAME_SIZE - 1] = '\0';
+		chinfo.src = eptinfo.src;
+		chinfo.dst = eptinfo.dst;
+	}
 
 	mutex_lock(&ctrldev->ctrl_lock);
 	switch (cmd) {
@@ -110,6 +121,16 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
 				chinfo.name, ret);
 		break;
 
+	case RPMSG_CREATE_EPT_FD_IOCTL:
+		ret = rpmsg_anonymous_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo,
+						    ept_fd_info.flags, &ept_fd_info.fd);
+		if (ret)
+			break;
+
+		if (copy_to_user(argp, &ept_fd_info, sizeof(ept_fd_info)))
+			ret = -EFAULT;
+		break;
+
 	default:
 		ret = -EINVAL;
 	}
diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
index f0c8da2b185b..02befb298f71 100644
--- a/include/uapi/linux/rpmsg.h
+++ b/include/uapi/linux/rpmsg.h
@@ -29,7 +29,8 @@ struct rpmsg_endpoint_info {
 #define RPMSG_CREATE_EPT_IOCTL	_IOW(0xb5, 0x1, struct rpmsg_endpoint_info)
 
 /**
- * Destroy a rpmsg char device endpoint created by the RPMSG_CREATE_EPT_IOCTL.
+ * Destroy a rpmsg char device endpoint created by the RPMSG_CREATE_EPT_IOCTL
+ * or RPMSG_CREATE_EPT_FD_IOCTL.
  */
 #define RPMSG_DESTROY_EPT_IOCTL	_IO(0xb5, 0x2)
 
@@ -53,4 +54,28 @@ struct rpmsg_endpoint_info {
  */
 #define RPMSG_SET_INCOMING_FLOWCONTROL _IOR(0xb5, 0x6, int)
 
+/**
+ * struct rpmsg_endpoint_fd_info - endpoint & fd info representation
+ * @name: name of service
+ * @src: local address. To set to RPMSG_ADDR_ANY if not used.
+ * @dst: destination address. To set to RPMSG_ADDR_ANY if not used.
+ * @flags: file flags of endpoint device, valid flags:
+ *         O_RDONLY/O_WRONLY/O_RDWR
+ *         O_NONBLOCK
+ *         O_CLOEXEC
+ * @fd: fd returned from driver
+ */
+struct rpmsg_endpoint_fd_info {
+	char name[32];
+	__u32 src;
+	__u32 dst;
+	__u32 flags;
+	__s32 fd;
+};
+
+/**
+ * Instantiate a new rmpsg endpoint which is represented by fd
+ */
+#define RPMSG_CREATE_EPT_FD_IOCTL _IOWR(0xb5, 0x7, struct rpmsg_endpoint_fd_info)
+
 #endif
-- 
2.25.1