cpu/stm32f4: adapted HWRNG implementation

cpu/stm32f4/periph/random.c → cpu/stm32f4/periph/hwrng.c

@@ -1,9 +1,9 @@
 /*
- * Copyright (C) 2014 Freie Universität Berlin
+ * Copyright (C) 2014-2016 Freie Universität Berlin
  *
- * This file is subject to the terms and conditions of the GNU Lesser General
- * Public License v2.1. See the file LICENSE in the top level directory for more
- * details.
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
  */
 
 /**
@@ -19,48 +19,40 @@
  */
 
 #include "cpu.h"
-#include "periph/random.h"
-#include "periph_conf.h"
+#include "periph/hwrng.h"
 
-/* ignore file in case no RNG device is defined */
-#if RANDOM_NUMOF
+/* only build if the CPU actually provides a RNG peripheral */
+#ifdef RNG
 
-void random_init(void)
+void hwrng_init(void)
 {
-    random_poweron();
+    /* no need for initialization */
 }
 
-int random_read(char *buf, unsigned int num)
+void hwrng_read(uint8_t *buf, unsigned int num)
 {
-    /* cppcheck-suppress variableScope */
-    uint32_t tmp;
     unsigned int count = 0;
 
+    /* power on and enable the device */
+    RCC->AHB2ENR |= RCC_AHB2ENR_RNGEN;
+    RNG->CR = RNG_CR_RNGEN;
+
+    /* get random data */
     while (count < num) {
         /* wait for random data to be ready to read */
         while (!(RNG->SR & RNG_SR_DRDY));
         /* read next 4 bytes */
-        tmp = RNG->DR;
+        uint32_t tmp = RNG->DR;
         /* copy data into result vector */
         for (int i = 0; i < 4 && count < num; i++) {
-            buf[count++] = (char)tmp;
+            buf[count++] = (uint8_t)tmp;
             tmp = tmp >> 8;
         }
     }
 
-    return (int)count;
-}
-
-void random_poweron(void)
-{
-    RCC->AHB2ENR |= RCC_AHB2ENR_RNGEN;
-    RNG->CR = RNG_CR_RNGEN;
-}
-
-void random_poweroff(void)
-{
+    /* finally disable the device again */
     RNG->CR = 0;
     RCC->AHB2ENR &= ~RCC_AHB2ENR_RNGEN;
 }
 
-#endif /* RANDOM_NUMOF */
+#endif /* CPUID_LEN */