Merge pull request #112 from DeeFuse/master

Add support for STM32

impl/random.h

@@ -23,6 +23,8 @@ static TLS struct {
 # include "random/mbed.h"
 #elif defined(RIOT_VERSION)
 # include "random/riot.h"
+#elif defined(STM32F4)
+# include "random/stm32.h"
 #else
 # error Unsupported platform
 #endif

impl/random/stm32.h

@@ -0,0 +1,47 @@
+
+// Use hardware RNG peripheral
+// Working with HAL, LL Driver (untested)
+
+#ifdef STM32F4
+
+#include "stm32f4xx.h"
+
+static int
+hydro_random_init(void)
+{
+    const char       ctx[hydro_hash_CONTEXTBYTES] = { 'h', 'y', 'd', 'r', 'o', 'P', 'R', 'G' };
+    hydro_hash_state st;
+    uint16_t         ebits = 0;
+
+    __IO uint32_t tmpreg;
+
+    // Enable RNG clock source
+    SET_BIT(RCC->AHB2ENR, RCC_AHB2ENR_RNGEN);
+
+    // Delay after an RCC peripheral clock enabling
+    tmpreg = READ_BIT(RCC->AHB2ENR, RCC_AHB2ENR_RNGEN);
+    UNUSED(tmpreg);
+
+    // RNG Peripheral enable
+    SET_BIT(RNG->CR, RNG_CR_RNGEN);
+
+    hydro_hash_init(&st, ctx, NULL);
+
+    while (ebits < 256) {
+        while (!(READ_BIT(RNG->SR, RNG_SR_DRDY))) {
+        }
+
+        uint32_t r = RNG->DR;
+        hydro_hash_update(&st, (const uint32_t*) &r, sizeof r);
+        ebits += 32;
+    }
+
+    hydro_hash_final(&st, hydro_random_context.state, sizeof hydro_random_context.state);
+    hydro_random_context.counter = ~LOAD64_LE(hydro_random_context.state);
+
+    return 0;
+}
+
+#else
+# error SMT32 implementation missing!
+#endif