ipc: Added IPC Service to support different transport backends

IPC Service allow plugging in different transport backends.
Specifies a generic API that is implemented by the backend.

Signed-off-by: Marcin Jeliński <marcin.jelinski@nordicsemi.no>

include/ipc/ipc_service.h

@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_IPC_SERVICE_IPC_SERVICE_H_
+#define ZEPHYR_INCLUDE_IPC_SERVICE_IPC_SERVICE_H_
+
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief IPC Service API
+ * @defgroup ipc_service_api IPC service APIs
+ * @{
+ */
+
+/** @brief Event callback structure.
+ *
+ *  It is registered during endpoint registration.
+ *  This structure is part of the endpoint configuration.
+ */
+struct ipc_service_cb {
+	/** @brief Bind was successful.
+	 *
+	 *  @param priv Private user data.
+	 */
+	void (*bound)(void *priv);
+
+	/** @brief New packet arrived.
+	 *
+	 *  @param data Pointer to data buffer.
+	 *  @param len Length of @a data.
+	 *  @param priv Private user data.
+	 */
+	void (*received)(const void *data, size_t len, void *priv);
+
+	/** @brief An error occurred.
+	 *
+	 *  @param message Error message.
+	 *  @param priv Private user data.
+	 */
+	void (*error)(const char *message, void *priv);
+};
+
+/** @brief Endpoint instance.
+ *
+ *  Content is not important for user of the API.
+ *  It is implemented in a specific backend.
+ */
+struct ipc_ept;
+
+/** @brief Endpoint configuration structure. */
+struct ipc_ept_cfg {
+
+	/** Name of the endpoint. */
+	const char *name;
+
+	/** Endpoint priority. If the backend supports priorities. */
+	int prio;
+
+	/** Event callback structure. */
+	struct ipc_service_cb cb;
+
+	/** Private user data. */
+	void *priv;
+};
+
+/** @brief Register IPC endpoint.
+ *
+ *  Registers IPC endpoint to enable communication with a remote device.
+ *
+ *  The same function registers endpoints for both master and slave devices.
+ *
+ *  @param ept Endpoint object.
+ *  @param cfg Endpoint configuration.
+ *
+ *  @retval -EIO when no backend is registered.
+ *  @retval -EINVAL when pointer to an endpoint or endpoint configuration is invalid.
+ *  @retval Other errno codes depending on the implementation of the backend.
+ */
+int ipc_service_register_endpoint(struct ipc_ept **ept, const struct ipc_ept_cfg *cfg);
+
+/** @brief Send data using given IPC endpoint.
+ *
+ *  @param ept Registered endpoint by @ref ipc_service_register_endpoint.
+ *  @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.
+ */
+int ipc_service_send(struct ipc_ept *ept, const void *data, size_t len);
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_IPC_SERVICE_IPC_SERVICE_H_ */

include/ipc/ipc_service_backend.h

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_IPC_SERVICE_IPC_SERVICE_BACKEND_H_
+#define ZEPHYR_INCLUDE_IPC_SERVICE_IPC_SERVICE_BACKEND_H_
+
+#include <ipc/ipc_service.h>
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief IPC Service backend
+ * @ingroup ipc_service_api
+ * @{
+ */
+
+/** @brief IPC backend configuration structure.
+ *
+ *  This structure is used for configuration backend during registration.
+ */
+struct ipc_service_backend {
+	/** @brief Name of the IPC backend. */
+	const char *name;
+
+	/** @brief Pointer to the function that will be used to send data to the endpoint.
+	 *
+	 *  @param ept Registered endpoint.
+	 *  @param data Pointer to the buffer to send.
+	 *  @param len Number of bytes to send.
+	 *
+	 *  @retval Status code.
+	 */
+	int (*send)(struct ipc_ept *ept, const void *data, size_t len);
+
+	/** @brief Pointer to the function that will be used to register endpoints.
+	 *
+	 *  @param ept Endpoint object.
+	 *  @param cfg Endpoint configuration.
+	 *
+	 *  @retval Status code.
+	 */
+	int (*register_endpoint)(struct ipc_ept **ept, const struct ipc_ept_cfg *cfg);
+};
+
+/** @brief IPC backend registration.
+ *
+ *  Registration must be done before using IPC Service.
+ *
+ *  @param backend Configuration of the backend.
+ *
+ *  @retval -EALREADY The backend is already registered.
+ *  @retval -EINVAL The backend configuration is incorrect.
+ *  @retval Zero on success.
+ *
+ */
+int ipc_service_register_backend(const struct ipc_service_backend *backend);
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_IPC_SERVICE_IPC_SERVICE_BACKEND_H_ */