HAL: add RGN API

Provides init, free and get numbers functions.

hal/hal/rng_api.h

@@ -0,0 +1,67 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2016 ARM Limited
+ *
+ * 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.
+ */
+#ifndef MBED_RNG_API_H
+#define MBED_RNG_API_H
+
+#include <stddef.h>
+#include "device.h"
+
+#if DEVICE_RNG
+
+/** RNG HAL structure. rng_s is declared in the target's HAL
+ */
+typedef struct rng_s rng_t;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \defgroup hal_rng RNG hal functions
+ * @{
+ */
+
+/** Initialize the RNG peripheral
+ *
+ * @param obj The RNG object
+ */
+void rng_init(rng_t *obj);
+
+/** Deinitialize the RNG peripheral
+ *
+ * @param obj The RNG object
+ */
+void rng_free(rng_t *obj);
+
+/** Get random data from RNG peripheral
+ *
+ * @param obj The RNG object
+ * @param output The pointer to an output array
+ * @param length The length of output data
+ * @param output_length The length of generated data
+ * @return 0 success, -1 fail
+ */
+int rng_get_numbers(rng_t *obj, uint8_t *output, size_t length, size_t *output_length);
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+#endif