blob: b71da09fd7a5b98a9e34ad3fbf626f31d28e4351 [file] [log] [blame]
/*
* Copyright (c) 2020 Lemonbeat GmbH
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT silabs_gecko_trng
#include <drivers/entropy.h>
#include <string.h>
#include "soc.h"
#include "em_cmu.h"
static void entropy_gecko_trng_read(uint8_t *output, size_t len)
{
uint32_t tmp;
uint32_t *data = (uint32_t *) output;
/* Read known good available data. */
while (len >= 4) {
*data++ = TRNG0->FIFO;
len -= 4;
}
if (len > 0) {
/* Handle the case where len is not a multiple of 4
* and FIFO data is available.
*/
tmp = TRNG0->FIFO;
memcpy(data, (const uint8_t *) &tmp, len);
}
}
static int entropy_gecko_trng_get_entropy(const struct device *dev,
uint8_t *buffer,
uint16_t length)
{
size_t count = 0;
size_t available;
ARG_UNUSED(dev);
while (length) {
available = TRNG0->FIFOLEVEL * 4;
if (available == 0) {
return -EINVAL;
}
count = SL_MIN(length, available);
entropy_gecko_trng_read(buffer, count);
buffer += count;
length -= count;
}
return 0;
}
static int entropy_gecko_trng_get_entropy_isr(const struct device *dev,
uint8_t *buf,
uint16_t len, uint32_t flags)
{
if ((flags & ENTROPY_BUSYWAIT) == 0U) {
/* No busy wait; return whatever data is available. */
size_t count;
size_t available = TRNG0->FIFOLEVEL * 4;
if (available == 0) {
return -ENODATA;
}
count = SL_MIN(len, available);
entropy_gecko_trng_read(buf, count);
return count;
} else {
/* Allowed to busy-wait */
int ret = entropy_gecko_trng_get_entropy(dev, buf, len);
if (ret == 0) {
/* Data retrieved successfully. */
return len;
}
return ret;
}
}
static int entropy_gecko_trng_init(const struct device *dev)
{
/* Enable the TRNG0 clock. */
CMU_ClockEnable(cmuClock_TRNG0, true);
/* Enable TRNG0. */
TRNG0->CONTROL = TRNG_CONTROL_ENABLE;
return 0;
}
static struct entropy_driver_api entropy_gecko_trng_api_funcs = {
.get_entropy = entropy_gecko_trng_get_entropy,
.get_entropy_isr = entropy_gecko_trng_get_entropy_isr
};
DEVICE_DT_INST_DEFINE(0,
entropy_gecko_trng_init, NULL,
NULL, NULL,
PRE_KERNEL_1, CONFIG_ENTROPY_INIT_PRIORITY,
&entropy_gecko_trng_api_funcs);