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![Alexander Shiyan](/assets/img/avatar_default.png)
This patch adds a watchdog driver for devices controlled through GPIO, (Analog Devices ADM706, Maxim MAX823, National NE555 etc). Signed-off-by: Alexander Shiyan <shc_work@mail.ru> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
254 lines
5.9 KiB
C
254 lines
5.9 KiB
C
/*
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* Driver for watchdog device controlled through GPIO-line
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*
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* Author: 2013, Alexander Shiyan <shc_work@mail.ru>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/err.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/notifier.h>
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#include <linux/of_gpio.h>
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#include <linux/platform_device.h>
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#include <linux/reboot.h>
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#include <linux/watchdog.h>
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#define SOFT_TIMEOUT_MIN 1
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#define SOFT_TIMEOUT_DEF 60
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#define SOFT_TIMEOUT_MAX 0xffff
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enum {
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HW_ALGO_TOGGLE,
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HW_ALGO_LEVEL,
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};
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struct gpio_wdt_priv {
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int gpio;
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bool active_low;
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bool state;
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unsigned int hw_algo;
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unsigned int hw_margin;
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unsigned long last_jiffies;
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struct notifier_block notifier;
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struct timer_list timer;
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struct watchdog_device wdd;
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};
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static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
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{
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gpio_set_value_cansleep(priv->gpio, !priv->active_low);
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/* Put GPIO back to tristate */
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if (priv->hw_algo == HW_ALGO_TOGGLE)
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gpio_direction_input(priv->gpio);
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}
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static int gpio_wdt_start(struct watchdog_device *wdd)
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{
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struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
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priv->state = priv->active_low;
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gpio_direction_output(priv->gpio, priv->state);
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priv->last_jiffies = jiffies;
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mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin);
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return 0;
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}
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static int gpio_wdt_stop(struct watchdog_device *wdd)
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{
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struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
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mod_timer(&priv->timer, 0);
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gpio_wdt_disable(priv);
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return 0;
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}
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static int gpio_wdt_ping(struct watchdog_device *wdd)
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{
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struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
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priv->last_jiffies = jiffies;
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return 0;
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}
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static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
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{
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wdd->timeout = t;
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return gpio_wdt_ping(wdd);
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}
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static void gpio_wdt_hwping(unsigned long data)
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{
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struct watchdog_device *wdd = (struct watchdog_device *)data;
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struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
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if (time_after(jiffies, priv->last_jiffies +
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msecs_to_jiffies(wdd->timeout * 1000))) {
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dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
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return;
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}
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/* Restart timer */
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mod_timer(&priv->timer, jiffies + priv->hw_margin);
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switch (priv->hw_algo) {
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case HW_ALGO_TOGGLE:
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/* Toggle output pin */
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priv->state = !priv->state;
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gpio_set_value_cansleep(priv->gpio, priv->state);
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break;
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case HW_ALGO_LEVEL:
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/* Pulse */
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gpio_set_value_cansleep(priv->gpio, !priv->active_low);
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udelay(1);
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gpio_set_value_cansleep(priv->gpio, priv->active_low);
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break;
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}
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}
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static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
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void *unused)
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{
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struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
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notifier);
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mod_timer(&priv->timer, 0);
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switch (code) {
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case SYS_HALT:
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case SYS_POWER_OFF:
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gpio_wdt_disable(priv);
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break;
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default:
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break;
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}
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return NOTIFY_DONE;
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}
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static const struct watchdog_info gpio_wdt_ident = {
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.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
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WDIOF_SETTIMEOUT,
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.identity = "GPIO Watchdog",
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};
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static const struct watchdog_ops gpio_wdt_ops = {
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.owner = THIS_MODULE,
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.start = gpio_wdt_start,
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.stop = gpio_wdt_stop,
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.ping = gpio_wdt_ping,
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.set_timeout = gpio_wdt_set_timeout,
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};
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static int gpio_wdt_probe(struct platform_device *pdev)
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{
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struct gpio_wdt_priv *priv;
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enum of_gpio_flags flags;
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unsigned int hw_margin;
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unsigned long f = 0;
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const char *algo;
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int ret;
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priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
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if (!gpio_is_valid(priv->gpio))
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return priv->gpio;
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priv->active_low = flags & OF_GPIO_ACTIVE_LOW;
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ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
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if (ret)
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return ret;
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if (!strncmp(algo, "toggle", 6)) {
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priv->hw_algo = HW_ALGO_TOGGLE;
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f = GPIOF_IN;
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} else if (!strncmp(algo, "level", 5)) {
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priv->hw_algo = HW_ALGO_LEVEL;
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f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
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} else {
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return -EINVAL;
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}
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ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,
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dev_name(&pdev->dev));
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if (ret)
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return ret;
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ret = of_property_read_u32(pdev->dev.of_node,
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"hw_margin_ms", &hw_margin);
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if (ret)
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return ret;
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/* Disallow values lower than 2 and higher than 65535 ms */
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if (hw_margin < 2 || hw_margin > 65535)
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return -EINVAL;
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/* Use safe value (1/2 of real timeout) */
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priv->hw_margin = msecs_to_jiffies(hw_margin / 2);
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watchdog_set_drvdata(&priv->wdd, priv);
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priv->wdd.info = &gpio_wdt_ident;
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priv->wdd.ops = &gpio_wdt_ops;
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priv->wdd.min_timeout = SOFT_TIMEOUT_MIN;
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priv->wdd.max_timeout = SOFT_TIMEOUT_MAX;
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if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
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priv->wdd.timeout = SOFT_TIMEOUT_DEF;
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setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
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ret = watchdog_register_device(&priv->wdd);
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if (ret)
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return ret;
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priv->notifier.notifier_call = gpio_wdt_notify_sys;
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ret = register_reboot_notifier(&priv->notifier);
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if (ret)
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watchdog_unregister_device(&priv->wdd);
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return ret;
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}
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static int gpio_wdt_remove(struct platform_device *pdev)
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{
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struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
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del_timer_sync(&priv->timer);
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unregister_reboot_notifier(&priv->notifier);
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watchdog_unregister_device(&priv->wdd);
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return 0;
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}
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static const struct of_device_id gpio_wdt_dt_ids[] = {
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{ .compatible = "linux,wdt-gpio", },
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{ }
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};
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MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
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static struct platform_driver gpio_wdt_driver = {
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.driver = {
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.name = "gpio-wdt",
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.owner = THIS_MODULE,
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.of_match_table = gpio_wdt_dt_ids,
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},
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.probe = gpio_wdt_probe,
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.remove = gpio_wdt_remove,
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};
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module_platform_driver(gpio_wdt_driver);
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MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
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MODULE_DESCRIPTION("GPIO Watchdog");
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MODULE_LICENSE("GPL");
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