rpmsg: core: Add channel creation internal API

Add the channel creation API as a first step to be able to define the
name service announcement as a rpmsg driver independent from the RPMsg
virtio bus.

Tested-by: Guennadi Liakhovetski <[e-mail]>
Signed-off-by: Arnaud Pouliquen <[e-mail]>
Signed-off-by: Mathieu Poirier <[e-mail]>
Reviewed-by: Guennadi Liakhovetski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bjorn Andersson <[e-mail]>

drivers/rpmsg/rpmsg_core.c

···
 #include "rpmsg_internal.h"
 
 /**
+ * rpmsg_create_channel() - create a new rpmsg channel
+ * using its name and address info.
+ * @rpdev: rpmsg device
+ * @chinfo: channel_info to bind
+ *
+ * Returns a pointer to the new rpmsg device on success, or NULL on error.
+ */
+struct rpmsg_device *rpmsg_create_channel(struct rpmsg_device *rpdev,
+					  struct rpmsg_channel_info *chinfo)
+{
+	if (WARN_ON(!rpdev))
+		return NULL;
+	if (!rpdev->ops || !rpdev->ops->create_channel) {
+		dev_err(&rpdev->dev, "no create_channel ops found\n");
+		return NULL;
+	}
+
+	return rpdev->ops->create_channel(rpdev, chinfo);
+}
+EXPORT_SYMBOL(rpmsg_create_channel);
+
+/**
+ * rpmsg_release_channel() - release a rpmsg channel
+ * using its name and address info.
+ * @rpdev: rpmsg device
+ * @chinfo: channel_info to bind
+ *
+ * Returns 0 on success or an appropriate error value.
+ */
+int rpmsg_release_channel(struct rpmsg_device *rpdev,
+			  struct rpmsg_channel_info *chinfo)
+{
+	if (WARN_ON(!rpdev))
+		return -EINVAL;
+	if (!rpdev->ops || !rpdev->ops->release_channel) {
+		dev_err(&rpdev->dev, "no release_channel ops found\n");
+		return -ENXIO;
+	}
+
+	return rpdev->ops->release_channel(rpdev, chinfo);
+}
+EXPORT_SYMBOL(rpmsg_release_channel);
+
+/**
  * rpmsg_create_ept() - create a new rpmsg_endpoint
  * @rpdev: rpmsg channel device
  * @cb: rx callback handler

drivers/rpmsg/rpmsg_internal.h

···
 
 /**
  * struct rpmsg_device_ops - indirection table for the rpmsg_device operations
+ * @create_channel:	create backend-specific channel, optional
+ * @release_channel:	release backend-specific channel, optional
  * @create_ept:		create backend-specific endpoint, required
  * @announce_create:	announce presence of new channel, optional
  * @announce_destroy:	announce destruction of channel, optional
···
  * advertise new channels implicitly by creating the endpoints.
  */
 struct rpmsg_device_ops {
+	struct rpmsg_device *(*create_channel)(struct rpmsg_device *rpdev,
+					       struct rpmsg_channel_info *chinfo);
+	int (*release_channel)(struct rpmsg_device *rpdev,
+			       struct rpmsg_channel_info *chinfo);
 	struct rpmsg_endpoint *(*create_ept)(struct rpmsg_device *rpdev,
 					    rpmsg_rx_cb_t cb, void *priv,
 					    struct rpmsg_channel_info chinfo);
···
 struct device *rpmsg_find_device(struct device *parent,
 				 struct rpmsg_channel_info *chinfo);
 
+struct rpmsg_device *rpmsg_create_channel(struct rpmsg_device *rpdev,
+					  struct rpmsg_channel_info *chinfo);
+int rpmsg_release_channel(struct rpmsg_device *rpdev,
+			  struct rpmsg_channel_info *chinfo);
 /**
  * rpmsg_chrdev_register_device() - register chrdev device based on rpdev
  * @rpdev:	prepared rpdev to be used for creating endpoints