ipc_service: Extend RPMsg structs and misc fixes

Extend the RPMsg structs to accommodate for the introduction of new
backends and contextually fix the ipc_rpmsg_static_vrings_mi backend
(the only user).

Rework also some comments and ipc_service glue code.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>

include/ipc/ipc_rpmsg.h

@@ -46,7 +46,10 @@ struct ipc_rpmsg_ept {
 	struct rpmsg_endpoint ep;
 
 	/** Name of the endpoint. */
-	const char *name;
+	char name[RPMSG_NAME_SIZE];
+
+	/** Destination endpoint. */
+	uint32_t dest;
 
 	/** Bound flag. */
 	volatile bool bound;
@@ -77,6 +80,9 @@ struct ipc_rpmsg_instance {
 
 	/** EPT (instance) callback. */
 	rpmsg_ept_cb cb;
+
+	/** Mutex for the instance. */
+	struct k_mutex mtx;
 };
 
 /** @brief Init an RPMsg instance.

include/ipc/ipc_service.h

@@ -136,15 +136,18 @@ int ipc_service_open_instance(const struct device *instance);
  *  Registers IPC endpoint onto an instance to enable communication with a
  *  remote device.
  *
- *  The same function registers endpoints for both master and slave devices.
+ *  The same function registers endpoints for both host and remote devices.
  *
  *  @param instance Instance to register the endpoint onto.
  *  @param ept Endpoint object.
  *  @param cfg Endpoint configuration.
  *
  *  @retval -EIO when no backend is registered.
- *  @retval -EINVAL when instance or endpoint configuration is invalid.
- *  @retval Other errno codes depending on the implementation of the backend.
+ *  @retval -EINVAL when instance, endpoint or configuration is invalid.
+ *  @retval -EBUSY when the instance is busy.
+ *
+ *  @retval 0 on success.
+ *  @retval other errno codes depending on the implementation of the backend.
  */
 int ipc_service_register_endpoint(const struct device *instance,
 				  struct ipc_ept *ept,
@@ -156,8 +159,14 @@ int ipc_service_register_endpoint(const struct device *instance,
  *  @param data Pointer to the buffer to send.
  *  @param len Number of bytes to send.
  *
- *  @retval -EIO when no backend is registered.
- *  @retval Other errno codes depending on the implementation of the backend.
+ *  @retval -EIO when no backend is registered or send hook is missing from
+ *	    backend.
+ *  @retval -EINVAL when instance or endpoint is invalid.
+ *  @retval -EBADMSG when the message is invalid.
+ *  @retval -EBUSY when the instance is busy.
+ *
+ *  @retval 0 on success.
+ *  @retval other errno codes depending on the implementation of the backend.
  */
 int ipc_service_send(struct ipc_ept *ept, const void *data, size_t len);
 

include/ipc/ipc_service_backend.h

@@ -44,7 +44,13 @@ struct ipc_service_backend {
 	 *  @param data Pointer to the buffer to send.
 	 *  @param len Number of bytes to send.
 	 *
-	 *  @retval Status code.
+	 *  @retval -EINVAL when instance is invalid.
+	 *  @retval -EBADMSG when the message is invalid.
+	 *  @retval -EBUSY when the instance is busy or not ready.
+	 *
+	 *  @retval 0 on success
+	 *  @retval other errno codes depending on the implementation of the
+	 *	    backend.
 	 */
 	int (*send)(const struct device *instance, void *token,
 		    const void *data, size_t len);
@@ -55,7 +61,12 @@ struct ipc_service_backend {
 	 *  @param token Backend-specific token.
 	 *  @param cfg Endpoint configuration.
 	 *
-	 *  @retval Status code.
+	 *  @retval -EINVAL when the endpoint configuration or instance is invalid.
+	 *  @retval -EBUSY when the instance is busy or not ready.
+	 *
+	 *  @retval 0 on success
+	 *  @retval other errno codes depending on the implementation of the
+	 *	    backend.
 	 */
 	int (*register_endpoint)(const struct device *instance,
 				 void **token,

include/ipc/ipc_static_vrings.h

@@ -24,6 +24,9 @@ extern "C" {
 /** Number of used VRING buffers. */
 #define VRING_COUNT	(2)
 
+/** VRING alignment. */
+#define VRING_ALIGNMENT	CONFIG_IPC_SERVICE_STATIC_VRINGS_ALIGNMENT
+
 /**
  * @typedef ipc_notify_cb
  * @brief Define the notify callback.