建立工程，成功创建两个虚拟串口

source/OpenAMP/open-amp/docs/rpmsg-design.md

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+# RPMsg Design Document
+RPMsg is a framework to allow communication between two processors.
+RPMsg implementation in OpenAMP library is based on virtio. It complies
+the RPMsg Linux kernel implementation. It defines the handshaking on
+setting up and tearing down the communication between applicaitons
+running on two processors.
+
+## RPMsg User API Flow Chats
+### RPMsg Static Endpoint
+![Static Endpoint](img/coprocessor-rpmsg-static-ep.png)
+### Binding Endpoint Dynamically with Name Service
+![Binding Endpoint Dynamically with Name Service](img/coprocessor-rpmsg-ns.png)
+### Creating Endpoint Dynamically with Name Service
+![Creating Endpoint Dynamically with Name Service](img/coprocessor-rpmsg-ns-dynamic.png)
+
+## RPMsg User APIs
+* RPMsg virtio master to initialize the shared buffers pool(RPMsg virtio slave
+  doesn't need to use this API):
+  ```
+  void rpmsg_virtio_init_shm_pool(struct rpmsg_virtio_shm_pool *shpool,
+				  void *shbuf, size_t size)
+  ```
+* Initialize RPMsg virtio device:
+  ```
+  int rpmsg_init_vdev(struct rpmsg_virtio_device *rvdev,
+		      struct virtio_device *vdev,
+		      rpmsg_ns_bind_cb ns_bind_cb,
+		      struct metal_io_region *shm_io,
+		      struct rpmsg_virtio_shm_pool *shpool)
+  ```
+* Deinitialize RPMsg virtio device:
+  ```
+  void rpmsg_deinit_vdev(struct rpmsg_virtio_device *rvdev)`
+  ```
+* Get RPMsg device from RPMsg virtio device:
+  ```
+  struct rpmsg_device *rpmsg_virtio_get_rpmsg_device(struct rpmsg_virtio_device *rvdev)
+  ```
+* Create RPMsg endpoint:
+  ```
+  int rpmsg_create_ept(struct rpmsg_endpoint *ept,
+		       struct rpmsg_device *rdev,
+		       const char *name, uint32_t src, uint32_t dest,
+		       rpmsg_ept_cb cb, rpmsg_ns_unbind_cb ns_unbind_cb)
+  ```
+* Destroy RPMsg endpoint:
+  ```
+  void rpmsg_destroy_ept(struct rpsmg_endpoint *ept)
+  ```
+* Check if the local RPMsg endpoint is binded to the remote, and ready to send
+  message:
+  ```
+  int is_rpmsg_ept_ready(struct rpmsg_endpoint *ept)
+  ```
+* Send message with RPMsg endpoint default binding:
+  ```
+  int rpmsg_send(struct rpmsg_endpoint *ept, const void *data, int len)
+  ```
+* Send message with RPMsg endpoint, specify destination address:
+  ```
+  int rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len,
+		   uint32_t dst)
+  ```
+* Send message with RPMsg endpoint using explicit source and destination
+  addresses:
+  ```
+  int rpmsg_send_offchannel(struct rpmsg_endpoint *ept,
+			    uint32_t src, uint32_t dst,
+			    const void *data, int len)
+  ```
+* Try to send message with RPMsg endpoint default binding, if no buffer
+  available, returns:
+  ```
+  int rpmsg_trysend(struct rpmsg_endpoint *ept, const void *data,
+		    int len)
+  ```
+* Try to send message with RPMsg endpoint, specify destination address,
+  if no buffer available, returns:
+  ```
+  int rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data, int len,
+		      uint32_t dst)
+  ```
+* Try to send message with RPMsg endpoint using explicit source and destination
+  addresses, if no buffer available, returns:
+  ```
+  int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept,
+			       uint32_t src, uint32_t dst,
+			       const void *data, int len)`
+  ```
+## RPMsg User Defined Callbacks
+* RPMsg endpoint message received callback:
+  ```
+  int (*rpmsg_ept_cb)(struct rpmsg_endpoint *ept, void *data,
+		      size_t len, uint32_t src, void *priv)
+  ```
+* RPMsg name service binding callback. If user defines such callback, when
+  there is a name service announcement arrives, if there is no registered
+  endpoint found to bind to this name service, it will call this callback.
+  If this callback is not defined, it will drop this name service.:
+  ```
+  void (*rpmsg_ns_bind_cb)(struct rpmsg_device *rdev,
+			   const char *name, uint32_t dest)
+  ```
+* RPMsg endpoint name service unbind callback. If user defines such callback,
+  when there is name service destroy arrives, it will call this callback to
+  notify the user application about the remote has destroyed the service.:
+  ```
+  void (*rpmsg_ns_unbind_cb)(struct rpmsg_endpoint *ept)
+  ```