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/*
* Copyright (c) 2016 Open-RnD Sp. z o.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @brief Driver for Independent Watchdog (IWDG) for STM32 MCUs
*
* Based on reference manual:
* STM32F101xx, STM32F102xx, STM32F103xx, STM32F105xx and STM32F107xx
* advanced ARM ® -based 32-bit MCUs
*
* Chapter 19: Independent watchdog (IWDG)
*
*/
#include <watchdog.h>
#include <soc.h>
#include <errno.h>
#include "iwdg_stm32.h"
#define AS_IWDG(__base_addr) \
(struct iwdg_stm32 *)(__base_addr)
static void iwdg_stm32_enable(struct device *dev)
{
volatile struct iwdg_stm32 *iwdg = AS_IWDG(IWDG_BASE);
ARG_UNUSED(dev);
iwdg->kr.bit.key = STM32_IWDG_KR_START;
}
static void iwdg_stm32_disable(struct device *dev)
{
/* watchdog cannot be stopped once started */
ARG_UNUSED(dev);
}
static int iwdg_stm32_set_config(struct device *dev,
struct wdt_config *config)
{
ARG_UNUSED(dev);
ARG_UNUSED(config);
/* no configuration */
return -ENOTSUP;
}
static void iwdg_stm32_get_config(struct device *dev,
struct wdt_config *config)
{
ARG_UNUSED(dev);
ARG_UNUSED(config);
}
static void iwdg_stm32_reload(struct device *dev)
{
volatile struct iwdg_stm32 *iwdg = AS_IWDG(IWDG_BASE);
ARG_UNUSED(dev);
iwdg->kr.bit.key = STM32_IWDG_KR_RELOAD;
}
static const struct wdt_driver_api iwdg_stm32_api = {
.enable = iwdg_stm32_enable,
.disable = iwdg_stm32_disable,
.get_config = iwdg_stm32_get_config,
.set_config = iwdg_stm32_set_config,
.reload = iwdg_stm32_reload,
};
static inline int __iwdg_stm32_prescaler(int setting)
{
int v;
int i = 0;
/* prescaler range 4 - 256 */
for (v = 4; v < 256; v *= 2, i++) {
if (v == setting)
return i;
}
return i;
}
static int iwdg_stm32_init(struct device *dev)
{
volatile struct iwdg_stm32 *iwdg = AS_IWDG(IWDG_BASE);
/* clock setup is not required, once the watchdog is enabled
* LSI oscillator will be forced on and fed to IWD after
* stabilization period
*/
/* unlock access to configuration registers */
iwdg->kr.bit.key = STM32_IWDG_KR_UNLOCK;
iwdg->pr.bit.pr =
__iwdg_stm32_prescaler(CONFIG_IWDG_STM32_PRESCALER);
iwdg->rlr.bit.rl = CONFIG_IWDG_STM32_RELOAD_COUNTER;
#ifdef CONFIG_IWDG_STM32_START_AT_BOOT
iwdg_stm32_enable(dev);
#endif
return 0;
}
DEVICE_AND_API_INIT(iwdg_stm32, CONFIG_IWDG_STM32_DEVICE_NAME, iwdg_stm32_init,
NULL, NULL,
PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
&iwdg_stm32_api);
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