blob: 281229b8212211e59f4ceb58004e57a0a471b7f5 [file] [log] [blame]
/*
* Copyright (c) 2020 Lemonbeat GmbH
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT silabs_gecko_trng
#include <zephyr/drivers/entropy.h>
#include <string.h>
#include "soc.h"
#include "em_cmu.h"
#if defined(CONFIG_CRYPTO_ACC_GECKO_TRNG)
/*
* Select the correct Crypto ACC FIFO memory base address.
*
* Problem: Gecko SDK doesn't provide macros that check if SL_TRUSTZONE is used or not for Crypto
* ACC RNGOUT FIFO memory base address, like it does for register address definitions.
*
* Solution: Check which register base address is used for the Crypto ACC peripheral and select an
* appropriate FIFO memory base address.
*/
#if (CRYPTOACC_BASE == CRYPTOACC_S_BASE)
#define S2_FIFO_BASE CRYPTOACC_RNGOUT_FIFO_S_MEM_BASE
#else
#define S2_FIFO_BASE CRYPTOACC_RNGOUT_FIFO_MEM_BASE
#endif
/**
* Series 2 SoCs have different TRNG register definitions
*/
#if defined(_SILICON_LABS_32B_SERIES_2_CONFIG_2) /* xG22 */
#define S2_FIFO_LEVEL (CRYPTOACC_RNGCTRL->FIFOLEVEL)
#define S2_CTRL (CRYPTOACC_RNGCTRL->RNGCTRL)
#define S2_CTRL_ENABLE (CRYPTOACC_RNGCTRL_ENABLE)
#elif defined(_SILICON_LABS_32B_SERIES_2_CONFIG_7) /* xG27 */
#define S2_FIFO_LEVEL (CRYPTOACC->NDRNG_FIFOLEVEL)
#define S2_CTRL (CRYPTOACC->NDRNG_CONTROL)
#define S2_CTRL_ENABLE (CRYPTOACC_NDRNG_CONTROL_ENABLE)
#else /* _SILICON_LABS_32B_SERIES_2_CONFIG_* */
#error "Building for unsupported Series 2 SoC"
#endif /* _SILICON_LABS_32B_SERIES_2_CONFIG_* */
#endif /* CONFIG_CRYPTO_ACC_GECKO_TRNG */
static void entropy_gecko_trng_read(uint8_t *output, size_t len)
{
#ifndef CONFIG_CRYPTO_ACC_GECKO_TRNG
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);
}
#else
memcpy(output, ((const uint8_t *) S2_FIFO_BASE), len);
#endif
}
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) {
#ifndef CONFIG_CRYPTO_ACC_GECKO_TRNG
available = TRNG0->FIFOLEVEL * 4;
#else
available = S2_FIFO_LEVEL * 4;
#endif
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;
#ifndef CONFIG_CRYPTO_ACC_GECKO_TRNG
size_t available = TRNG0->FIFOLEVEL * 4;
#else
size_t available = S2_FIFO_LEVEL * 4;
#endif
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. */
#ifndef CONFIG_CRYPTO_ACC_GECKO_TRNG
CMU_ClockEnable(cmuClock_TRNG0, true);
/* Enable TRNG0. */
TRNG0->CONTROL = TRNG_CONTROL_ENABLE;
#else
/* Enable the CRYPTO ACC clock. */
CMU_ClockEnable(cmuClock_CRYPTOACC, true);
/* Enable TRNG */
S2_CTRL |= S2_CTRL_ENABLE;
#endif
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);