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Elixir Cross Referencer

 * Copyright (c) 2017 Intel Corporation
 * SPDX-License-Identifier: Apache-2.0

#include <string.h>
#include <random.h>

static inline u32_t random_esp32_get_u32(void)
	/* The documentation specifies the random number generator at the
	 * following address, which is at odds with the SDK, that specifies
	 * it at 0x60035144.  The fact that they're 0x200c0000 bytes apart
	 * (lower 16 bits are the same) suggests this might be the same
	 * register, just mirrored somewhere else in the address space.
	 * Confirmation is required.
	volatile u32_t *rng_data_reg = (u32_t *)0x3ff75144;

	/* Read just once.  This is not optimal as the generator has
	 * limited throughput due to scarce sources of entropy, specially
	 * with the radios turned off.  Might want to revisit this.
	return *rng_data_reg;

static int random_esp32_get_entropy(struct device *device, u8_t *buf, u16_t len)
	while (len) {
		u32_t v = random_esp32_get_u32();

		if (len >= sizeof(v)) {
			memcpy(buf, &v, sizeof(v));

			buf += sizeof(v);
			len -= sizeof(v);
		} else {
			memcpy(buf, &v, len);

	return 0;

static int random_esp32_init(struct device *device)
	return 0;

static struct random_driver_api random_esp32_api_funcs = {
	.get_entropy = random_esp32_get_entropy

		    random_esp32_init, NULL, NULL,

u32_t sys_rand32_get(void)
	return random_esp32_get_u32();