zephyr/drivers/entropy/entropy_esp32.c

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/*
* Copyright (c) 2017 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <string.h>
#include <drivers/entropy.h>
static inline u32_t entropy_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 entropy_esp32_get_entropy(struct device *device, u8_t *buf, u16_t len)
{
while (len) {
u32_t v = entropy_esp32_get_u32();
if (len >= sizeof(v)) {
memcpy(buf, &v, sizeof(v));
buf += sizeof(v);
len -= sizeof(v);
} else {
memcpy(buf, &v, len);
break;
}
}
return 0;
}
static int entropy_esp32_init(struct device *device)
{
return 0;
}
static struct entropy_driver_api entropy_esp32_api_funcs = {
.get_entropy = entropy_esp32_get_entropy
};
DEVICE_AND_API_INIT(entropy_esp32, CONFIG_ENTROPY_NAME,
entropy_esp32_init, NULL, NULL,
PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
&entropy_esp32_api_funcs);