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Commit 25134eaf authored by Alexander Shiyan's avatar Alexander Shiyan Committed by Wim Van Sebroeck
Browse files

watchdog: GPIO-controlled watchdog 



This patch adds a watchdog driver for devices controlled through GPIO,
(Analog Devices ADM706, Maxim MAX823, National NE555 etc).

Signed-off-by: default avatarAlexander Shiyan <shc_work@mail.ru>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWim Van Sebroeck <wim@iguana.be>
parent 8832b200

Documentation/devicetree/bindings/watchdog/gpio-wdt.txt

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* GPIO-controlled Watchdog



Required Properties:

- compatible: Should contain "linux,wdt-gpio".

- gpios: From common gpio binding; gpio connection to WDT reset pin.

- hw_algo: The algorithm used by the driver. Should be one of the

  following values:

  - toggle: Either a high-to-low or a low-to-high transition clears

    the WDT counter. The watchdog timer is disabled when GPIO is

    left floating or connected to a three-state buffer.

  - level: Low or high level starts counting WDT timeout,

    the opposite level disables the WDT. Active level is determined

    by the GPIO flags.

- hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds).



Example:

	watchdog: watchdog {

		/* ADM706 */

		compatible = "linux,wdt-gpio";

		gpios = <&gpio3 9 GPIO_ACTIVE_LOW>;

		hw_algo = "toggle";

		hw_margin_ms = <1600>;

	};

drivers/watchdog/Kconfig

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@@ -87,6 +87,14 @@ config DA9055_WATCHDOG 
	  This driver can also be built as a module.  If so, the module

	  will be called da9055_wdt.



config GPIO_WATCHDOG

	tristate "Watchdog device controlled through GPIO-line"

	depends on OF_GPIO

	select WATCHDOG_CORE

	help

	  If you say yes here you get support for watchdog device

	  controlled through GPIO-line.



config WM831X_WATCHDOG

	tristate "WM831x watchdog"

	depends on MFD_WM831X

drivers/watchdog/Makefile

+1 −0
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@@ -172,6 +172,7 @@ obj-$(CONFIG_XEN_WDT) += xen_wdt.o 
# Architecture Independent

obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o

obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o

obj-$(CONFIG_GPIO_WATCHDOG)	+= gpio_wdt.o

obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o

obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o

obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o

drivers/watchdog/gpio_wdt.c

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/*

 * Driver for watchdog device controlled through GPIO-line

 *

 * Author: 2013, Alexander Shiyan <shc_work@mail.ru>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 */



#include <linux/err.h>

#include <linux/delay.h>

#include <linux/module.h>

#include <linux/notifier.h>

#include <linux/of_gpio.h>

#include <linux/platform_device.h>

#include <linux/reboot.h>

#include <linux/watchdog.h>



#define SOFT_TIMEOUT_MIN	1

#define SOFT_TIMEOUT_DEF	60

#define SOFT_TIMEOUT_MAX	0xffff



enum {

	HW_ALGO_TOGGLE,

	HW_ALGO_LEVEL,

};



struct gpio_wdt_priv {

	int			gpio;

	bool			active_low;

	bool			state;

	unsigned int		hw_algo;

	unsigned int		hw_margin;

	unsigned long		last_jiffies;

	struct notifier_block	notifier;

	struct timer_list	timer;

	struct watchdog_device	wdd;

};



static void gpio_wdt_disable(struct gpio_wdt_priv *priv)

{

	gpio_set_value_cansleep(priv->gpio, !priv->active_low);



	/* Put GPIO back to tristate */

	if (priv->hw_algo == HW_ALGO_TOGGLE)

		gpio_direction_input(priv->gpio);

}



static int gpio_wdt_start(struct watchdog_device *wdd)

{

	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);



	priv->state = priv->active_low;

	gpio_direction_output(priv->gpio, priv->state);

	priv->last_jiffies = jiffies;

	mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin);



	return 0;

}



static int gpio_wdt_stop(struct watchdog_device *wdd)

{

	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);



	mod_timer(&priv->timer, 0);

	gpio_wdt_disable(priv);



	return 0;

}



static int gpio_wdt_ping(struct watchdog_device *wdd)

{

	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);



	priv->last_jiffies = jiffies;



	return 0;

}



static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)

{

	wdd->timeout = t;



	return gpio_wdt_ping(wdd);

}



static void gpio_wdt_hwping(unsigned long data)

{

	struct watchdog_device *wdd = (struct watchdog_device *)data;

	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);



	if (time_after(jiffies, priv->last_jiffies +

		       msecs_to_jiffies(wdd->timeout * 1000))) {

		dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");

		return;

	}



	/* Restart timer */

	mod_timer(&priv->timer, jiffies + priv->hw_margin);



	switch (priv->hw_algo) {

	case HW_ALGO_TOGGLE:

		/* Toggle output pin */

		priv->state = !priv->state;

		gpio_set_value_cansleep(priv->gpio, priv->state);

		break;

	case HW_ALGO_LEVEL:

		/* Pulse */

		gpio_set_value_cansleep(priv->gpio, !priv->active_low);

		udelay(1);

		gpio_set_value_cansleep(priv->gpio, priv->active_low);

		break;

	}

}



static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,

			       void *unused)

{

	struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,

						  notifier);



	mod_timer(&priv->timer, 0);



	switch (code) {

	case SYS_HALT:

	case SYS_POWER_OFF:

		gpio_wdt_disable(priv);

		break;

	default:

		break;

	}



	return NOTIFY_DONE;

}



static const struct watchdog_info gpio_wdt_ident = {

	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |

			  WDIOF_SETTIMEOUT,

	.identity	= "GPIO Watchdog",

};



static const struct watchdog_ops gpio_wdt_ops = {

	.owner		= THIS_MODULE,

	.start		= gpio_wdt_start,

	.stop		= gpio_wdt_stop,

	.ping		= gpio_wdt_ping,

	.set_timeout	= gpio_wdt_set_timeout,

};



static int gpio_wdt_probe(struct platform_device *pdev)

{

	struct gpio_wdt_priv *priv;

	enum of_gpio_flags flags;

	unsigned int hw_margin;

	unsigned long f = 0;

	const char *algo;

	int ret;



	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);

	if (!priv)

		return -ENOMEM;



	priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);

	if (!gpio_is_valid(priv->gpio))

		return priv->gpio;



	priv->active_low = flags & OF_GPIO_ACTIVE_LOW;



	ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);

	if (ret)

		return ret;

	if (!strncmp(algo, "toggle", 6)) {

		priv->hw_algo = HW_ALGO_TOGGLE;

		f = GPIOF_IN;

	} else if (!strncmp(algo, "level", 5)) {

		priv->hw_algo = HW_ALGO_LEVEL;

		f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;

	} else {

		return -EINVAL;

	}



	ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,

				    dev_name(&pdev->dev));

	if (ret)

		return ret;



	ret = of_property_read_u32(pdev->dev.of_node,

				   "hw_margin_ms", &hw_margin);

	if (ret)

		return ret;

	/* Disallow values lower than 2 and higher than 65535 ms */

	if (hw_margin < 2 || hw_margin > 65535)

		return -EINVAL;



	/* Use safe value (1/2 of real timeout) */

	priv->hw_margin = msecs_to_jiffies(hw_margin / 2);



	watchdog_set_drvdata(&priv->wdd, priv);



	priv->wdd.info		= &gpio_wdt_ident;

	priv->wdd.ops		= &gpio_wdt_ops;

	priv->wdd.min_timeout	= SOFT_TIMEOUT_MIN;

	priv->wdd.max_timeout	= SOFT_TIMEOUT_MAX;



	if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)

		priv->wdd.timeout = SOFT_TIMEOUT_DEF;



	setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);



	ret = watchdog_register_device(&priv->wdd);

	if (ret)

		return ret;



	priv->notifier.notifier_call = gpio_wdt_notify_sys;

	ret = register_reboot_notifier(&priv->notifier);

	if (ret)

		watchdog_unregister_device(&priv->wdd);



	return ret;

}



static int gpio_wdt_remove(struct platform_device *pdev)

{

	struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);



	del_timer_sync(&priv->timer);

	unregister_reboot_notifier(&priv->notifier);

	watchdog_unregister_device(&priv->wdd);



	return 0;

}



static const struct of_device_id gpio_wdt_dt_ids[] = {

	{ .compatible = "linux,wdt-gpio", },

	{ }

};

MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);



static struct platform_driver gpio_wdt_driver = {

	.driver	= {

		.name		= "gpio-wdt",

		.owner		= THIS_MODULE,

		.of_match_table	= gpio_wdt_dt_ids,

	},

	.probe	= gpio_wdt_probe,

	.remove	= gpio_wdt_remove,

};

module_platform_driver(gpio_wdt_driver);



MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");

MODULE_DESCRIPTION("GPIO Watchdog");

MODULE_LICENSE("GPL");