psa: Add stubbed PSA client implementation

Add a stubbed PSA Client API implementation for application
compatibility. The interface is non-functional, but provides sane error
codes.

features/FEATURE_EXPERIMENTAL_API/FEATURE_PSA/TARGET_MBED_PSA_SRV/inc/psa/client.h

@@ -25,6 +25,10 @@
 #include <stddef.h>
 #include "psa/error.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #if !defined(UINT32_MAX)
 #define UINT32_MAX ((uint32_t)-1)
 #endif
@@ -53,5 +57,99 @@ typedef struct psa_outvec {
     size_t len;      /**< Length in bytes of the buffer.*/
 } psa_outvec;
 
+/**
+ * \brief Retrieve the version of the PSA Framework API that is implemented.
+ *
+ * \return version              The version of the PSA Framework implementation
+ *                              that is providing the runtime services to the
+ *                              caller. The major and minor version are encoded
+ *                              as follows:
+ * \arg                           version[15:8] -- major version number.
+ * \arg                           version[7:0]  -- minor version number.
+ */
+uint32_t psa_framework_version(void);
+
+/**
+ * \brief Retrieve the version of an RoT Service or indicate that it is not
+ *        present on this system.
+ *
+ * \param[in] sid               ID of the RoT Service to query.
+ *
+ * \retval PSA_VERSION_NONE     The RoT Service is not implemented, or the
+ *                              caller is not permitted to access the service.
+ * \retval > 0                  The version of the implemented RoT Service.
+ */
+uint32_t psa_version(uint32_t sid);
+
+/**
+ * \brief Connect to an RoT Service by its SID.
+ *
+ * \param[in] sid               ID of the RoT Service to connect to.
+ * \param[in] version           Requested version of the RoT Service.
+ *
+ * \retval > 0                  A handle for the connection.
+ * \retval PSA_ERROR_CONNECTION_REFUSED The SPM or RoT Service has refused the
+ *                              connection.
+ * \retval PSA_ERROR_CONNECTION_BUSY The SPM or RoT Service cannot make the
+ *                              connection at the moment.
+ * \retval "PROGRAMMER ERROR"   The call is a PROGRAMMER ERROR if one or more
+ *                              of the following are true:
+ * \arg                           The RoT Service ID is not present.
+ * \arg                           The RoT Service version is not supported.
+ * \arg                           The caller is not allowed to access the RoT
+ *                                service.
+ */
+psa_handle_t psa_connect(uint32_t sid, uint32_t version);
+
+/**
+ * \brief Call an RoT Service on an established connection.
+ *
+ * \param[in] handle            A handle to an established connection.
+ * \param[in] type              The reuqest type.
+ *                              Must be zero( \ref PSA_IPC_CALL) or positive.
+ * \param[in] in_vec            Array of input \ref psa_invec structures.
+ * \param[in] in_len            Number of input \ref psa_invec structures.
+ * \param[in/out] out_vec       Array of output \ref psa_outvec structures.
+ * \param[in] out_len           Number of output \ref psa_outvec structures.
+ *
+ * \retval >=0                  RoT Service-specific status value.
+ * \retval <0                   RoT Service-specific error code.
+ * \retval PSA_ERROR_PROGRAMMER_ERROR The connection has been terminated by the
+ *                              RoT Service. The call is a PROGRAMMER ERROR if
+ *                              one or more of the following are true:
+ * \arg                           An invalid handle was passed.
+ * \arg                           The connection is already handling a request.
+ * \arg                           type < 0.
+ * \arg                           An invalid memory reference was provided.
+ * \arg                           in_len + out_len > PSA_MAX_IOVEC.
+ * \arg                           The message is unrecognized by the RoT
+ *                                Service or incorrectly formatted.
+ */
+psa_status_t psa_call(psa_handle_t handle, int32_t type,
+                      const psa_invec *in_vec,
+                      size_t in_len,
+                      psa_outvec *out_vec,
+                      size_t out_len);
+
+/**
+ * \brief Close a connection to an RoT Service.
+ *
+ * \param[in] handle            A handle to an established connection, or the
+ *                              null handle.
+ *
+ * \retval void                 Success.
+ * \retval "PROGRAMMER ERROR"   The call is a PROGRAMMER ERROR if one or more
+ *                              of the following are true:
+ * \arg                           An invalid handle was provided that is not
+ *                                the null handle.
+ * \arg                           The connection is currently handling a
+ *                                request.
+ */
+void psa_close(psa_handle_t handle);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif // __MBED_OS_DEFAULT_PSA_CLIENT_API_H__
 #endif

features/FEATURE_EXPERIMENTAL_API/FEATURE_PSA/TARGET_MBED_PSA_SRV/src/client.c

@@ -0,0 +1,51 @@
+/* Copyright (c) 2017-2020 ARM Limited
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* This implementation of the PSA Client API is provided for application
+ * compatibility on single v7-M targets. The client implementation is stubbed
+ * and non-functional, but present and returns sane errors. */
+
+#include "psa/client.h"
+
+uint32_t psa_framework_version(void)
+{
+    return PSA_FRAMEWORK_VERSION;
+}
+
+uint32_t psa_version(uint32_t sid)
+{
+    return PSA_VERSION_NONE;
+}
+
+psa_handle_t psa_connect(uint32_t sid, uint32_t version)
+{
+    return PSA_ERROR_PROGRAMMER_ERROR;
+}
+
+psa_status_t psa_call(psa_handle_t handle, int32_t type,
+                      const psa_invec *in_vec,
+                      size_t in_len,
+                      psa_outvec *out_vec,
+                      size_t out_len)
+{
+    return PSA_ERROR_PROGRAMMER_ERROR;
+}
+
+void psa_close(psa_handle_t handle)
+{
+    return;
+}