Diff: mbed-dev/targets/TARGET_STM/trng_api.c

Revision:

18:6a4db94011d3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-dev/targets/TARGET_STM/trng_api.c	Sun May 14 23:18:57 2017 +0000
@@ -0,0 +1,88 @@
+/*
+ *  Hardware entropy collector for the STM32 families
+ *
+ *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ *  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.
+ *
+ */
+
+#if defined(DEVICE_TRNG)
+
+#include <stdlib.h>
+#include "cmsis.h"
+#include "trng_api.h"
+
+/** trng_get_byte
+ *  @brief Get one byte of entropy from the RNG, assuming it is up and running.
+ *  @param obj TRNG obj
+ *  @param pointer to the hardware generated random byte.
+ */
+static void trng_get_byte(trng_t *obj, unsigned char *byte )
+{
+    *byte = (unsigned char)HAL_RNG_GetRandomNumber(&obj->handle);
+}
+
+void trng_init(trng_t *obj)
+{
+#if defined(TARGET_STM32L4)
+    RCC_PeriphCLKInitTypeDef PeriphClkInitStruct;
+
+    /*Select PLLQ output as RNG clock source */
+    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RNG;
+    PeriphClkInitStruct.RngClockSelection = RCC_RNGCLKSOURCE_PLL;
+    HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct);
+#endif
+
+    /* RNG Peripheral clock enable */
+    __HAL_RCC_RNG_CLK_ENABLE();
+
+    /* Initialize RNG instance */
+    obj->handle.Instance = RNG;
+    HAL_RNG_Init(&obj->handle);
+
+    /* first random number generated after setting the RNGEN bit should not be used */
+    HAL_RNG_GetRandomNumber(&obj->handle);
+
+}
+
+void trng_free(trng_t *obj)
+{
+    /*Disable the RNG peripheral */
+    HAL_RNG_DeInit(&obj->handle);
+    /* RNG Peripheral clock disable - assume we're the only users of RNG  */
+    __HAL_RCC_RNG_CLK_DISABLE();
+}
+
+int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
+{
+    int ret;
+
+    /* Get Random byte */
+    for( uint32_t i = 0; i < length; i++ ){
+        trng_get_byte(obj, output + i );
+    }
+
+    *output_length = length;
+    /* Just be extra sure that we didn't do it wrong */
+    if( ( __HAL_RNG_GET_FLAG(&obj->handle, (RNG_FLAG_CECS | RNG_FLAG_SECS)) ) != 0 ) {
+        ret = -1;
+    } else {
+        ret = 0;
+    }
+
+    return( ret );
+}
+
+#endif