Add a weak implementation for trng_get_bytes()

Author: danny4478

features/mbedtls/platform/TARGET_PSA/COMPONENT_NSPE/src/psa_hrng.c

@@ -0,0 +1,56 @@
+/* Copyright (c) 2018 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.
+ */
+
+#include "trng_api.h"
+#include "crypto.h"
+
+#if DEVICE_TRNG
+
+__WEAK void trng_init(trng_t *obj)
+{
+    (void)(obj);
+}
+
+
+__WEAK void trng_free(trng_t *obj)
+{
+    (void)(obj);
+}
+
+__WEAK int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
+{
+    if (output == NULL){
+        return -1;
+    }
+
+    if(psa_crypto_init() != PSA_SUCCESS) {
+        return -1;
+    }
+
+    if (psa_generate_random(output, length) != PSA_SUCCESS) {
+        return -1;
+    }
+
+    mbedtls_psa_crypto_free();
+
+    ((void)(obj));
+    ((void)(output_length));
+
+    return 0;
+}
+
+#endif  // DEVICE_TRNG

targets/targets.json

@@ -98,6 +98,7 @@
     "NSPE_Target": {
         "inherits": ["PSA_Target"],
         "components": ["PSA_SRV_IPC", "NSPE"],
+        "device_has_add": ["TRNG"],
         "public": false
     },
     "SPE_Target": {