blob: f442686118f8e12ec1d666d47ab12216c1cc6ae5 [file] [log] [blame]
/*
* Copyright (c) 2017 Erwin Rol <erwin@erwinrol.com>
* Copyright (c) 2018 Nordic Semiconductor ASA
* Copyright (c) 2017 Exati Tecnologia Ltda.
* Copyright (c) 2020 STMicroelectronics.
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT st_stm32_rng
#include <kernel.h>
#include <device.h>
#include <drivers/entropy.h>
#include <random/rand32.h>
#include <init.h>
#include <sys/__assert.h>
#include <sys/util.h>
#include <errno.h>
#include <soc.h>
#include <stm32_ll_bus.h>
#include <stm32_ll_rcc.h>
#include <stm32_ll_rng.h>
#include <stm32_ll_system.h>
#include <sys/printk.h>
#include <drivers/clock_control.h>
#include <drivers/clock_control/stm32_clock_control.h>
#include "stm32_hsem.h"
#define IRQN DT_INST_IRQN(0)
#define IRQ_PRIO DT_INST_IRQ(0, priority)
/*
* This driver need to take into account all STM32 family:
* - simple rng without harware fifo and no DMA.
* - Variable delay between two consecutive random numbers
* (depending on family and clock settings)
*
*
* Due to the first byte in a stream of bytes being more costly on
* some platforms a "water system" inspired algorithm is used to
* amortize the cost of the first byte.
*
* The algorithm will delay generation of entropy until the amount of
* bytes goes below THRESHOLD, at which point it will generate entropy
* until the BUF_LEN limit is reached.
*
* The entropy level is checked at the end of every consumption of
* entropy.
*
*/
struct rng_pool {
uint8_t first_alloc;
uint8_t first_read;
uint8_t last;
uint8_t mask;
uint8_t threshold;
uint8_t buffer[0];
};
#define RNG_POOL_DEFINE(name, len) uint8_t name[sizeof(struct rng_pool) + (len)]
BUILD_ASSERT((CONFIG_ENTROPY_STM32_ISR_POOL_SIZE &
(CONFIG_ENTROPY_STM32_ISR_POOL_SIZE - 1)) == 0,
"The CONFIG_ENTROPY_STM32_ISR_POOL_SIZE must be a power of 2!");
BUILD_ASSERT((CONFIG_ENTROPY_STM32_THR_POOL_SIZE &
(CONFIG_ENTROPY_STM32_THR_POOL_SIZE - 1)) == 0,
"The CONFIG_ENTROPY_STM32_THR_POOL_SIZE must be a power of 2!");
struct entropy_stm32_rng_dev_cfg {
struct stm32_pclken pclken;
};
struct entropy_stm32_rng_dev_data {
RNG_TypeDef *rng;
const struct device *clock;
struct k_sem sem_lock;
struct k_sem sem_sync;
RNG_POOL_DEFINE(isr, CONFIG_ENTROPY_STM32_ISR_POOL_SIZE);
RNG_POOL_DEFINE(thr, CONFIG_ENTROPY_STM32_THR_POOL_SIZE);
};
#define DEV_DATA(dev) \
((struct entropy_stm32_rng_dev_data *)(dev)->data)
#define DEV_CFG(dev) \
((const struct entropy_stm32_rng_dev_cfg *)(dev)->config)
static const struct entropy_stm32_rng_dev_cfg entropy_stm32_rng_config = {
.pclken = { .bus = DT_INST_CLOCKS_CELL(0, bus),
.enr = DT_INST_CLOCKS_CELL(0, bits) },
};
static struct entropy_stm32_rng_dev_data entropy_stm32_rng_data = {
.rng = (RNG_TypeDef *)DT_INST_REG_ADDR(0),
};
static int entropy_stm32_got_error(RNG_TypeDef *rng)
{
__ASSERT_NO_MSG(rng != NULL);
if (LL_RNG_IsActiveFlag_CECS(rng)) {
return 1;
}
if (LL_RNG_IsActiveFlag_SECS(rng)) {
return 1;
}
return 0;
}
static int random_byte_get(void)
{
int retval = -EAGAIN;
unsigned int key;
key = irq_lock();
if ((LL_RNG_IsActiveFlag_DRDY(entropy_stm32_rng_data.rng) == 1)) {
if (entropy_stm32_got_error(entropy_stm32_rng_data.rng)) {
retval = -EIO;
} else {
retval = LL_RNG_ReadRandData32(
entropy_stm32_rng_data.rng);
}
}
irq_unlock(key);
return retval;
}
#pragma GCC push_options
#if defined(CONFIG_BT_CTLR_FAST_ENC)
#pragma GCC optimize ("Ofast")
#endif
static uint16_t rng_pool_get(struct rng_pool *rngp, uint8_t *buf, uint16_t len)
{
uint32_t last = rngp->last;
uint32_t mask = rngp->mask;
uint8_t *dst = buf;
uint32_t first, available;
uint32_t other_read_in_progress;
unsigned int key;
key = irq_lock();
first = rngp->first_alloc;
/*
* The other_read_in_progress is non-zero if rngp->first_read != first,
* which means that lower-priority code (which was interrupted by this
* call) already allocated area for read.
*/
other_read_in_progress = (rngp->first_read ^ first);
available = (last - first) & mask;
if (available < len) {
len = available;
}
/*
* Move alloc index forward to signal, that part of the buffer is
* now reserved for this call.
*/
rngp->first_alloc = (first + len) & mask;
irq_unlock(key);
while (likely(len--)) {
*dst++ = rngp->buffer[first];
first = (first + 1) & mask;
}
/*
* If this call is the last one accessing the pool, move read index
* to signal that all allocated regions are now read and could be
* overwritten.
*/
if (likely(!other_read_in_progress)) {
key = irq_lock();
rngp->first_read = rngp->first_alloc;
irq_unlock(key);
}
len = dst - buf;
available = available - len;
if (available <= rngp->threshold) {
LL_RNG_EnableIT(entropy_stm32_rng_data.rng);
}
return len;
}
#pragma GCC pop_options
static int rng_pool_put(struct rng_pool *rngp, uint8_t byte)
{
uint8_t first = rngp->first_read;
uint8_t last = rngp->last;
uint8_t mask = rngp->mask;
/* Signal error if the pool is full. */
if (((last - first) & mask) == mask) {
return -ENOBUFS;
}
rngp->buffer[last] = byte;
rngp->last = (last + 1) & mask;
return 0;
}
static void rng_pool_init(struct rng_pool *rngp, uint16_t size,
uint8_t threshold)
{
rngp->first_alloc = 0U;
rngp->first_read = 0U;
rngp->last = 0U;
rngp->mask = size - 1;
rngp->threshold = threshold;
}
static void stm32_rng_isr(const void *arg)
{
int byte, ret;
ARG_UNUSED(arg);
byte = random_byte_get();
if (byte < 0) {
return;
}
ret = rng_pool_put((struct rng_pool *)(entropy_stm32_rng_data.isr),
byte);
if (ret < 0) {
ret = rng_pool_put(
(struct rng_pool *)(entropy_stm32_rng_data.thr),
byte);
if (ret < 0) {
LL_RNG_DisableIT(entropy_stm32_rng_data.rng);
}
k_sem_give(&entropy_stm32_rng_data.sem_sync);
}
}
static int entropy_stm32_rng_get_entropy(const struct device *device,
uint8_t *buf,
uint16_t len)
{
/* Check if this API is called on correct driver instance. */
__ASSERT_NO_MSG(&entropy_stm32_rng_data == DEV_DATA(device));
while (len) {
uint16_t bytes;
k_sem_take(&entropy_stm32_rng_data.sem_lock, K_FOREVER);
bytes = rng_pool_get(
(struct rng_pool *)(entropy_stm32_rng_data.thr),
buf, len);
k_sem_give(&entropy_stm32_rng_data.sem_lock);
if (bytes == 0U) {
/* Pool is empty: Sleep until next interrupt. */
k_sem_take(&entropy_stm32_rng_data.sem_sync, K_FOREVER);
continue;
}
len -= bytes;
buf += bytes;
}
return 0;
}
static int entropy_stm32_rng_get_entropy_isr(const struct device *dev,
uint8_t *buf,
uint16_t len,
uint32_t flags)
{
uint16_t cnt = len;
/* Check if this API is called on correct driver instance. */
__ASSERT_NO_MSG(&entropy_stm32_rng_data == DEV_DATA(dev));
if (likely((flags & ENTROPY_BUSYWAIT) == 0U)) {
return rng_pool_get(
(struct rng_pool *)(entropy_stm32_rng_data.isr),
buf, len);
}
if (len) {
unsigned int key;
int irq_enabled;
key = irq_lock();
irq_enabled = irq_is_enabled(IRQN);
irq_disable(IRQN);
irq_unlock(key);
/* Clear NVIC pending bit. This ensures that a subsequent
* RNG event will set the Cortex-M single-bit event register
* to 1 (the bit is set when NVIC pending IRQ status is
* changed from 0 to 1)
*/
NVIC_ClearPendingIRQ(IRQN);
do {
int byte;
while (LL_RNG_IsActiveFlag_DRDY(
entropy_stm32_rng_data.rng) != 1) {
/*
* To guarantee waking up from the event, the
* SEV-On-Pend feature must be enabled (enabled
* during ARCH initialization).
*
* DSB is recommended by spec before WFE (to
* guarantee completion of memory transactions)
*/
__DSB();
__WFE();
__SEV();
__WFE();
}
byte = random_byte_get();
NVIC_ClearPendingIRQ(IRQN);
if (byte < 0) {
continue;
}
buf[--len] = byte;
} while (len);
if (irq_enabled) {
irq_enable(IRQN);
}
}
return cnt;
}
static int entropy_stm32_rng_init(const struct device *dev)
{
struct entropy_stm32_rng_dev_data *dev_data;
const struct entropy_stm32_rng_dev_cfg *dev_cfg;
int res;
__ASSERT_NO_MSG(dev != NULL);
dev_data = DEV_DATA(dev);
dev_cfg = DEV_CFG(dev);
__ASSERT_NO_MSG(dev_data != NULL);
__ASSERT_NO_MSG(dev_cfg != NULL);
#if CONFIG_SOC_SERIES_STM32L4X
/* Configure PLLSA11 to enable 48M domain */
LL_RCC_PLLSAI1_ConfigDomain_48M(LL_RCC_PLLSOURCE_MSI,
LL_RCC_PLLM_DIV_1,
24, LL_RCC_PLLSAI1Q_DIV_2);
/* Enable PLLSA1 */
LL_RCC_PLLSAI1_Enable();
/* Enable PLLSAI1 output mapped on 48MHz domain clock */
LL_RCC_PLLSAI1_EnableDomain_48M();
/* Wait for PLLSA1 ready flag */
while (LL_RCC_PLLSAI1_IsReady() != 1) {
}
/* Write the peripherals independent clock configuration register :
* choose PLLSAI1 source as the 48 MHz clock is needed for the RNG
* Linear Feedback Shift Register
*/
LL_RCC_SetRNGClockSource(LL_RCC_RNG_CLKSOURCE_PLLSAI1);
#elif defined(RCC_CR2_HSI48ON) || defined(RCC_CR_HSI48ON) \
|| defined(RCC_CRRCR_HSI48ON)
#if CONFIG_SOC_SERIES_STM32L0X
/* We need SYSCFG to control VREFINT, so make sure it is clocked */
if (!LL_APB2_GRP1_IsEnabledClock(LL_APB2_GRP1_PERIPH_SYSCFG)) {
return -EINVAL;
}
/* HSI48 requires VREFINT (see RM0376 section 7.2.4). */
LL_SYSCFG_VREFINT_EnableHSI48();
#endif /* CONFIG_SOC_SERIES_STM32L0X */
z_stm32_hsem_lock(CFG_HW_CLK48_CONFIG_SEMID, HSEM_LOCK_DEFAULT_RETRY);
/* Use the HSI48 for the RNG */
LL_RCC_HSI48_Enable();
while (!LL_RCC_HSI48_IsReady()) {
/* Wait for HSI48 to become ready */
}
LL_RCC_SetRNGClockSource(LL_RCC_RNG_CLKSOURCE_HSI48);
#if !defined(CONFIG_SOC_SERIES_STM32WBX)
/* Specially for STM32WB, don't unlock the HSEM to prevent M0 core
* to disable HSI48 clock used for RNG.
*/
z_stm32_hsem_unlock(CFG_HW_CLK48_CONFIG_SEMID);
#endif /* CONFIG_SOC_SERIES_STM32WBX */
#endif /* CONFIG_SOC_SERIES_STM32L4X */
dev_data->clock = device_get_binding(STM32_CLOCK_CONTROL_NAME);
__ASSERT_NO_MSG(dev_data->clock != NULL);
res = clock_control_on(dev_data->clock,
(clock_control_subsys_t *)&dev_cfg->pclken);
__ASSERT_NO_MSG(res == 0);
LL_RNG_EnableIT(dev_data->rng);
LL_RNG_Enable(dev_data->rng);
/* Locking semaphore initialized to 1 (unlocked) */
k_sem_init(&dev_data->sem_lock, 1, 1);
/* Synching semaphore */
k_sem_init(&dev_data->sem_sync, 0, 1);
rng_pool_init((struct rng_pool *)(dev_data->thr),
CONFIG_ENTROPY_STM32_THR_POOL_SIZE,
CONFIG_ENTROPY_STM32_THR_THRESHOLD);
rng_pool_init((struct rng_pool *)(dev_data->isr),
CONFIG_ENTROPY_STM32_ISR_POOL_SIZE,
CONFIG_ENTROPY_STM32_ISR_THRESHOLD);
IRQ_CONNECT(IRQN, IRQ_PRIO, stm32_rng_isr, &entropy_stm32_rng_data, 0);
irq_enable(IRQN);
return 0;
}
static const struct entropy_driver_api entropy_stm32_rng_api = {
.get_entropy = entropy_stm32_rng_get_entropy,
.get_entropy_isr = entropy_stm32_rng_get_entropy_isr
};
DEVICE_DT_INST_DEFINE(0,
entropy_stm32_rng_init, device_pm_control_nop,
&entropy_stm32_rng_data, &entropy_stm32_rng_config,
PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
&entropy_stm32_rng_api);