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wdt_sam.c
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wdt_sam.c
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/*
* Copyright (C) 2017 Intel Deutschland GmbH
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT atmel_sam_watchdog
/**
* @brief Watchdog (WDT) Driver for Atmel SAM MCUs
*
* Note:
* - Once the watchdog disable bit is set, it cannot be cleared till next
* power reset, i.e, the watchdog cannot be started once stopped.
* - Since the MCU boots with WDT enabled, the CONFIG_WDT_DISABLE_AT_BOOT
* is set default at boot and watchdog module is disabled in the MCU for
* systems that don't need watchdog functionality.
* - If the application needs to use the watchdog in the system, then
* CONFIG_WDT_DISABLE_AT_BOOT must be unset in the app's config file
*/
#include <zephyr/drivers/watchdog.h>
#include <zephyr/irq.h>
#include <soc.h>
#define LOG_LEVEL CONFIG_WDT_LOG_LEVEL
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(wdt_sam);
#define SAM_PRESCALAR 128
#define WDT_MAX_VALUE 4095
/* Device constant configuration parameters */
struct wdt_sam_dev_cfg {
Wdt *regs;
};
struct wdt_sam_dev_data {
wdt_callback_t cb;
uint32_t mode;
bool timeout_valid;
bool mode_set;
};
static struct wdt_sam_dev_data wdt_sam_data = { 0 };
static void wdt_sam_isr(const struct device *dev)
{
const struct wdt_sam_dev_cfg *config = dev->config;
uint32_t wdt_sr;
Wdt * const wdt = config->regs;
struct wdt_sam_dev_data *data = dev->data;
/* Clear status bit to acknowledge interrupt by dummy read. */
wdt_sr = wdt->WDT_SR;
data->cb(dev, 0);
}
/**
* @brief Calculates the watchdog counter value (WDV)
* to be installed in the watchdog timer
*
* @param timeout Timeout value in milliseconds.
* @param slow clock on board in Hz.
*/
int wdt_sam_convert_timeout(uint32_t timeout, uint32_t sclk)
{
uint32_t max, min;
timeout = timeout * 1000U;
min = (SAM_PRESCALAR * 1000000) / sclk;
max = min * WDT_MAX_VALUE;
if ((timeout < min) || (timeout > max)) {
LOG_ERR("Invalid timeout value allowed range:"
"%d ms to %d ms", min / 1000U, max / 1000U);
return -EINVAL;
}
return WDT_MR_WDV(timeout / min);
}
static int wdt_sam_disable(const struct device *dev)
{
const struct wdt_sam_dev_cfg *config = dev->config;
Wdt * const wdt = config->regs;
struct wdt_sam_dev_data *data = dev->data;
/* since Watchdog mode register is 'write-once', we can't disable if
* someone has already set the mode register
*/
if (data->mode_set) {
return -EPERM;
}
/* do we handle -EFAULT here */
/* Watchdog Mode register is 'write-once' only register.
* Once disabled, it cannot be enabled until the device is reset
*/
wdt->WDT_MR |= WDT_MR_WDDIS;
data->mode_set = true;
return 0;
}
static int wdt_sam_setup(const struct device *dev, uint8_t options)
{
const struct wdt_sam_dev_cfg *config = dev->config;
Wdt * const wdt = config->regs;
struct wdt_sam_dev_data *data = dev->data;
if (!data->timeout_valid) {
LOG_ERR("No valid timeouts installed");
return -EINVAL;
}
/* since Watchdog mode register is 'write-once', we can't set if
* someone has already set the mode register
*/
if (data->mode_set) {
return -EPERM;
}
if ((options & WDT_OPT_PAUSE_IN_SLEEP) == WDT_OPT_PAUSE_IN_SLEEP) {
data->mode |= WDT_MR_WDIDLEHLT;
}
if ((options & WDT_OPT_PAUSE_HALTED_BY_DBG) ==
WDT_OPT_PAUSE_HALTED_BY_DBG) {
data->mode |= WDT_MR_WDDBGHLT;
}
wdt->WDT_MR = data->mode;
data->mode_set = true;
return 0;
}
static int wdt_sam_install_timeout(const struct device *dev,
const struct wdt_timeout_cfg *cfg)
{
uint32_t wdt_mode = 0U;
int timeout_value;
struct wdt_sam_dev_data *data = dev->data;
if (data->timeout_valid) {
LOG_ERR("No more timeouts can be installed");
return -ENOMEM;
}
if (cfg->window.min != 0U) {
return -EINVAL;
}
/*
* Convert time to cycles. SAM3X SoC doesn't supports window
* timeout config. So the api expects the timeout to be filled
* in the max field of the timeout config.
*/
timeout_value = wdt_sam_convert_timeout(cfg->window.max,
(uint32_t) CHIP_FREQ_XTAL_32K);
if (timeout_value < 0) {
return -EINVAL;
}
switch (cfg->flags) {
case WDT_FLAG_RESET_SOC:
/*A Watchdog fault (underflow or error) activates all resets */
wdt_mode = WDT_MR_WDRSTEN; /* WDT reset enable */
break;
case WDT_FLAG_RESET_NONE:
/* A Watchdog fault (underflow or error) asserts interrupt. */
if (cfg->callback) {
wdt_mode = WDT_MR_WDFIEN; /* WDT fault interrupt. */
data->cb = cfg->callback;
} else {
LOG_ERR("Invalid(NULL) ISR callback passed\n");
return -EINVAL;
}
break;
/* Processor only reset mode not available in same70 series */
#ifdef WDT_MR_WDRPROC
case WDT_FLAG_RESET_CPU_CORE:
/*A Watchdog fault activates the processor reset*/
LOG_DBG("Configuring reset CPU only mode\n");
wdt_mode = WDT_MR_WDRSTEN | /* WDT reset enable */
WDT_MR_WDRPROC; /* WDT reset processor only*/
break;
#endif
default:
LOG_ERR("Unsupported watchdog config Flag\n");
return -ENOTSUP;
}
data->mode = wdt_mode |
WDT_MR_WDV(timeout_value) |
WDT_MR_WDD(timeout_value);
data->timeout_valid = true;
return 0;
}
static int wdt_sam_feed(const struct device *dev, int channel_id)
{
const struct wdt_sam_dev_cfg *config = dev->config;
/*
* On watchdog restart the Watchdog counter is immediately
* reloaded/fed with the 12-bit watchdog counter
* value from WDT_MR and restarted
*/
Wdt * const wdt = config->regs;
wdt->WDT_CR |= WDT_CR_KEY_PASSWD | WDT_CR_WDRSTT;
return 0;
}
static const struct wdt_driver_api wdt_sam_api = {
.setup = wdt_sam_setup,
.disable = wdt_sam_disable,
.install_timeout = wdt_sam_install_timeout,
.feed = wdt_sam_feed,
};
static const struct wdt_sam_dev_cfg wdt_sam_cfg = {
.regs = (Wdt *)DT_INST_REG_ADDR(0),
};
static void wdt_sam_irq_config(void)
{
IRQ_CONNECT(DT_INST_IRQN(0),
DT_INST_IRQ(0, priority), wdt_sam_isr,
DEVICE_DT_INST_GET(0), 0);
irq_enable(DT_INST_IRQN(0));
}
static int wdt_sam_init(const struct device *dev)
{
#ifdef CONFIG_WDT_DISABLE_AT_BOOT
wdt_sam_disable(dev);
#endif
wdt_sam_irq_config();
return 0;
}
DEVICE_DT_INST_DEFINE(0, wdt_sam_init, NULL,
&wdt_sam_data, &wdt_sam_cfg, PRE_KERNEL_1,
CONFIG_KERNEL_INIT_PRIORITY_DEVICE, &wdt_sam_api);