mirror of
https://github.com/RIOT-OS/RIOT.git
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144 lines
3.1 KiB
C
144 lines
3.1 KiB
C
/*
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* Copyright (C) 2019 Inria
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup cpu_stm32
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* @ingroup drivers_periph_wdt
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*
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* @brief
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*
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* @{
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*
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* @file wdt.c
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* @brief Independent Watchdog timer for STM32L platforms
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*
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* @author Francisco Molina <francois-xavier.molina@inria.fr>
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*/
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#include <stdlib.h>
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#include <assert.h>
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#include <inttypes.h>
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#include "cpu.h"
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#include "timex.h"
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#include "periph_cpu.h"
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#include "periph/wdt.h"
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#define ENABLE_DEBUG 0
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#include "debug.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define MAX_RELOAD (4096U)
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#define MAX_PRESCALER (6U)
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#define IWDG_STEP_MS ((4U * US_PER_MS * MAX_RELOAD) / CLOCK_LSI)
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#define IWDG_KR_KEY_RELOAD ((uint16_t)0xAAAA)
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#define IWDG_KR_KEY_ENABLE ((uint16_t)0xCCCC)
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#define IWDG_UNLOCK ((uint16_t)0x5555)
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#define IWDG_LOCK ((uint16_t)0x0000)
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static inline uint32_t _wdt_time(uint8_t pre, uint16_t rel)
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{
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/* wdt_time (us) = LSI(us) x 4 x 2^PRE x RELOAD */
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return (uint32_t)(((uint64_t) US_PER_SEC * 4 * (1 << pre) * rel ) / CLOCK_LSI);
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}
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static inline void _iwdt_unlock(void)
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{
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IWDG->KR = IWDG_UNLOCK;
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}
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static inline void _iwdt_lock(void)
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{
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IWDG->KR = IWDG_LOCK;
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}
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static void _set_prescaler(uint8_t prescaler)
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{
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assert(prescaler <= MAX_PRESCALER);
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_iwdt_unlock();
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IWDG->PR = prescaler;
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_iwdt_lock();
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}
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static void _set_reload(uint16_t reload)
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{
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assert(reload <= IWDG_RLR_RL);
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_iwdt_unlock();
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IWDG->RLR = reload;
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_iwdt_lock();
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}
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static uint8_t _find_prescaler(uint32_t rst_time)
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{
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/* Divide by the range to get power of 2 of the prescaler */
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uint8_t pre = 32U - __builtin_clz(rst_time / IWDG_STEP_MS);
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DEBUG("[wdt]: prescaler value %d\n", pre);
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return pre;
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}
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static uint16_t _find_reload_value(uint8_t pre, uint32_t rst_time)
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{
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/* Calculate best reload value = rst_time / LSI(ms) x 4 x 2^PRE */
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uint16_t rel = (uint16_t)((rst_time * CLOCK_LSI) / \
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((uint32_t) (US_PER_MS * 4 * (1 << pre))));
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DEBUG("[wdt]: reload value %d\n", rel);
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return rel;
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}
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void wdt_start(void)
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{
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IWDG->KR = IWDG_KR_KEY_ENABLE;
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}
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#ifdef CPU_FAM_STM32L4
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void wdt_init(void)
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{
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FLASH->OPTR |= ~(FLASH_OPTR_IWDG_STOP || FLASH_OPTR_IWDG_STDBY);
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}
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#endif
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void wdt_kick(void)
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{
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IWDG->KR = IWDG_KR_KEY_RELOAD;
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}
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void wdt_setup_reboot(uint32_t min_time, uint32_t max_time)
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{
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(void) min_time;
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/* Windowed wdt not supported */
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assert(min_time == 0);
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/* Check reset time limit */
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assert((max_time > NWDT_TIME_LOWER_LIMIT) || \
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(max_time < NWDT_TIME_UPPER_LIMIT));
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uint8_t pre = _find_prescaler(max_time);
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uint16_t rel = _find_reload_value(pre, max_time);
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/* Set watchdog prescaler and reload value */
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_set_prescaler(pre);
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_set_reload(rel);
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DEBUG("[wdt]: reset time %" PRIu32 " [us]\n", _wdt_time(pre, rel));
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/* Refresh wdt counter */
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wdt_kick();
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}
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#ifdef __cplusplus
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}
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#endif
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