Merge pull request #1294 from haukepetersen/add_arduinodue_rng_driver

cpu: Add random number generator driver for the SAM3X8E

boards/arduino-due/include/periph_conf.h

@@ -79,6 +79,12 @@
 #define UART_1_PINS
 /** @} */
 
+/**
+ * @name Random Number Generator configuration
+ * @{
+ */
+#define RANDOM_NUMOF        (1U)
+/** @} */
 
 /**
  * @name GPIO configuration

cpu/sam3x8e/periph/random.c

@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+/**
+ * @ingroup     driver_periph
+ * @{
+ *
+ * @file
+ * @brief       Low-level random number generator driver implementation
+ *
+ * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
+ *
+ * @}
+ */
+
+#include "cpu.h"
+#include "periph_conf.h"
+#include "periph/random.h"
+
+/* only compile this driver if enabled in the board's periph_conf.h */
+#if RANDOM_NUMOF
+
+/**
+ * @name KEY needs to be written to the config register when en|disabling
+ *       random number generation
+ */
+#define KEY             (0x524e4700)
+
+void random_init(void)
+{
+    random_poweron();
+}
+
+int random_read(char *buf, unsigned int num)
+{
+    uint32_t tmp;
+    int count = 0;
+
+    while (count < num) {
+        /* wait until new value is generated -> takes up to 84 cycles */
+        while (!(TRNG->TRNG_ISR & TRNG_ISR_DATRDY));
+        /* read 4 byte of random data */
+        tmp = TRNG->TRNG_ODATA;
+        /* extract copy bytes to result */
+        for (int i = 0; i < 4 && count < num; i++) {
+            buf[count++] = (char)tmp;
+            tmp = tmp >> 8;
+        }
+    }
+
+    return count;
+}
+
+void random_poweron(void)
+{
+    /* enable clock signal for TRNG module */
+    PMC->PMC_PCER1 |= PMC_PCER1_PID41;
+    /* enable the generation of random numbers */
+    TRNG->TRNG_CR |= (KEY | TRNG_CR_ENABLE);
+}
+
+void random_poweroff(void)
+{
+    /* disable the generation of random numbers */
+    TRNG->TRNG_CR &= ~(KEY | TRNG_CR_ENABLE);
+    /* disable clock signal for TRNG module */
+    PMC->PMC_PCER1 &= ~(PMC_PCER1_PID41);
+}
+
+#endif /* RANDOM_NUMOF */

tests/periph_random/Makefile

@@ -0,0 +1,10 @@
+export APPLICATION = periph_random
+include ../Makefile.tests_common
+
+BOARD_BLACKLIST := chronos mbed_lpc1768 msb-430 msb-430h native qemu-i386 redbee-econotag telosb \
+                   wsn430-v1_3b wsn430-v1_4 z1
+# all listed boards: no periph_conf.h defined,
+
+USEMODULE += vtimer
+
+include $(RIOTBASE)/Makefile.include

tests/periph_random/README.md

@@ -0,0 +1,7 @@
+Expected result
+===============
+This test outputs a sequence of random bytes, starting with one, then two and so on, until 20 random bytes are printed. Then the application sleeps for a second and starts over.
+
+Background
+==========
+This test was introduced to test the implementation of the low-level random number generator driver. For most platforms the implementation is based on hardware CPU peripherals.

tests/periph_random/main.c

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+/**
+ * @ingroup tests
+ * @{
+ *
+ * @file
+ * @brief       Low-level random number generator driver test
+ *
+ * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <vtimer.h>
+#include <periph/random.h>
+#include <periph_conf.h>
+
+/* only compile test if a random number generator is defined */
+#if RANDOM_NUMOF
+
+#define LIMIT       (20U)
+
+int main(void)
+{
+    char buf[LIMIT];
+    int count = 0;
+
+    puts("\nRandom number generator low-level driver test\n");
+    printf("This test will print from 1 to %i random bytes about every second\n\n", LIMIT);
+
+    puts("Initializing Random Number Generator driver.\n");
+    random_init();
+
+    while (1) {
+        /* zero out buffer */
+        memset(buf, 0, sizeof(buf));
+
+        /* create random numbers */
+        for (int i = 1; i <= LIMIT; i++) {
+            printf("generating %i random byte(s)\n", i);
+            count = random_read(buf, i);
+
+            if (count != i) {
+                printf("Error generating random bytes, got %i instead of %i", count, i);
+                return 0;
+            }
+
+            printf("Got:");
+            for (int j = 0; j < i; j++) {
+                printf(" 0x%02x", buf[j]);
+            }
+            printf("\n");
+        }
+
+        vtimer_usleep(1000 * 1000);
+    }
+
+    return 0;
+}
+
+#else
+
+int main(void)
+{
+    puts("Random number generator low-level driver test");
+    puts("There is no (pseudo) random generator implementation for your platform");
+    return 0;
+}
+
+#endif /* RANDOM_NUMOF */