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

Revision:

0:9b3d4731edbb

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os/targets/TARGET_STM/trng_api.c	Thu Jun 21 13:51:43 2018 +0000
@@ -0,0 +1,100 @@
+/*
+ *  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"
+#include "mbed_error.h"
+#include "mbed_critical.h"
+
+static uint8_t users = 0;
+
+void trng_init(trng_t *obj)
+{
+    uint32_t dummy;
+
+    /*  We're only supporting a single user of RNG */
+    if (core_util_atomic_incr_u8(&users, 1) > 1 ) {
+        error("Only 1 RNG instance supported\r\n");
+    }
+
+#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;
+    obj->handle.State = HAL_RNG_STATE_RESET;
+    obj->handle.Lock = HAL_UNLOCKED;
+
+    HAL_RNG_Init(&obj->handle);
+
+    /* first random number generated after setting the RNGEN bit should not be used */
+    HAL_RNG_GenerateRandomNumber(&obj->handle, &dummy);
+}
+
+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();
+
+    users = 0;
+}
+
+int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
+{
+    int ret = 0;
+    volatile uint8_t random[4];
+    *output_length = 0;
+
+    /* Get Random byte */
+    while ((*output_length < length) && (ret ==0)) {
+        if ( HAL_RNG_GenerateRandomNumber(&obj->handle, (uint32_t *)random ) != HAL_OK) {
+                ret = -1;
+        } else {
+            for (uint8_t i =0; (i < 4) && (*output_length < length) ; i++) {
+                *output++ = random[i];
+                *output_length += 1;
+                random[i] = 0;
+            }
+        }
+    }
+
+    /* 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;
+    }
+
+    return( ret );
+}
+
+#endif