[mirror_ubuntu-zesty-kernel.git] / drivers / watchdog / gpio_wdt.c

/*
 * 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;
	bool			always_running;
	bool			armed;
	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 void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)
{
	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);
}

static int gpio_wdt_start(struct watchdog_device *wdd)
{
	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);

	gpio_wdt_start_impl(priv);
	priv->armed = true;

	return 0;
}

static int gpio_wdt_stop(struct watchdog_device *wdd)
{
	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);

	priv->armed = false;
	if (!priv->always_running) {
		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 (priv->armed && 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);

	priv->always_running = of_property_read_bool(pdev->dev.of_node,
						     "always-running");

	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)
		goto error_unregister;

	if (priv->always_running)
		gpio_wdt_start_impl(priv);

	return 0;

error_unregister:
	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",
		.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");
Commit	Line	Data
25134eaf AS	1	/*
	2	* Driver for watchdog device controlled through GPIO-line
	3	*
	4	* Author: 2013, Alexander Shiyan <shc_work@mail.ru>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*/
	11
	12	#include <linux/err.h>
	13	#include <linux/delay.h>
	14	#include <linux/module.h>
	15	#include <linux/notifier.h>
	16	#include <linux/of_gpio.h>
	17	#include <linux/platform_device.h>
	18	#include <linux/reboot.h>
	19	#include <linux/watchdog.h>
	20
	21	#define SOFT_TIMEOUT_MIN 1
	22	#define SOFT_TIMEOUT_DEF 60
	23	#define SOFT_TIMEOUT_MAX 0xffff
	24
	25	enum {
	26	HW_ALGO_TOGGLE,
	27	HW_ALGO_LEVEL,
	28	};
	29
	30	struct gpio_wdt_priv {
	31	int gpio;
	32	bool active_low;
	33	bool state;
ba804a95 ML	34	bool always_running;
ba804a95 ML	35	bool armed;
25134eaf AS	36	unsigned int hw_algo;
	37	unsigned int hw_margin;
	38	unsigned long last_jiffies;
	39	struct notifier_block notifier;
	40	struct timer_list timer;
	41	struct watchdog_device wdd;
	42	};
	43
	44	static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
	45	{
	46	gpio_set_value_cansleep(priv->gpio, !priv->active_low);
	47
	48	/* Put GPIO back to tristate */
	49	if (priv->hw_algo == HW_ALGO_TOGGLE)
	50	gpio_direction_input(priv->gpio);
	51	}
	52
ba804a95	53	static void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)
25134eaf	54	{
25134eaf AS	55	priv->state = priv->active_low;
	56	gpio_direction_output(priv->gpio, priv->state);
	57	priv->last_jiffies = jiffies;
	58	mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin);
ba804a95 ML	59	}
	60
	61	static int gpio_wdt_start(struct watchdog_device *wdd)
	62	{
	63	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
	64
	65	gpio_wdt_start_impl(priv);
	66	priv->armed = true;
25134eaf AS	67
	68	return 0;
	69	}
	70
	71	static int gpio_wdt_stop(struct watchdog_device *wdd)
	72	{
	73	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
	74
ba804a95 ML	75	priv->armed = false;
	76	if (!priv->always_running) {
	77	mod_timer(&priv->timer, 0);
	78	gpio_wdt_disable(priv);
	79	}
25134eaf AS	80
	81	return 0;
	82	}
	83
	84	static int gpio_wdt_ping(struct watchdog_device *wdd)
	85	{
	86	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
	87
	88	priv->last_jiffies = jiffies;
	89
	90	return 0;
	91	}
	92
	93	static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
	94	{
	95	wdd->timeout = t;
	96
	97	return gpio_wdt_ping(wdd);
	98	}
	99
	100	static void gpio_wdt_hwping(unsigned long data)
	101	{
	102	struct watchdog_device wdd = (struct watchdog_device )data;
	103	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
	104
ba804a95 ML	105	if (priv->armed && time_after(jiffies, priv->last_jiffies +
ba804a95 ML	106	msecs_to_jiffies(wdd->timeout * 1000))) {
25134eaf AS	107	dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
	108	return;
	109	}
	110
	111	/* Restart timer */
	112	mod_timer(&priv->timer, jiffies + priv->hw_margin);
	113
	114	switch (priv->hw_algo) {
	115	case HW_ALGO_TOGGLE:
	116	/* Toggle output pin */
	117	priv->state = !priv->state;
	118	gpio_set_value_cansleep(priv->gpio, priv->state);
	119	break;
	120	case HW_ALGO_LEVEL:
	121	/* Pulse */
	122	gpio_set_value_cansleep(priv->gpio, !priv->active_low);
	123	udelay(1);
	124	gpio_set_value_cansleep(priv->gpio, priv->active_low);
	125	break;
	126	}
	127	}
	128
	129	static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
	130	void *unused)
	131	{
	132	struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
	133	notifier);
	134
	135	mod_timer(&priv->timer, 0);
	136
	137	switch (code) {
	138	case SYS_HALT:
	139	case SYS_POWER_OFF:
	140	gpio_wdt_disable(priv);
	141	break;
	142	default:
	143	break;
	144	}
	145
	146	return NOTIFY_DONE;
	147	}
	148
	149	static const struct watchdog_info gpio_wdt_ident = {
	150	.options = WDIOF_MAGICCLOSE \| WDIOF_KEEPALIVEPING \|
	151	WDIOF_SETTIMEOUT,
	152	.identity = "GPIO Watchdog",
	153	};
	154
	155	static const struct watchdog_ops gpio_wdt_ops = {
	156	.owner = THIS_MODULE,
	157	.start = gpio_wdt_start,
	158	.stop = gpio_wdt_stop,
	159	.ping = gpio_wdt_ping,
	160	.set_timeout = gpio_wdt_set_timeout,
	161	};
	162
	163	static int gpio_wdt_probe(struct platform_device *pdev)
	164	{
	165	struct gpio_wdt_priv *priv;
	166	enum of_gpio_flags flags;
	167	unsigned int hw_margin;
	168	unsigned long f = 0;
	169	const char *algo;
	170	int ret;
171
172	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
173	if (!priv)
174	return -ENOMEM;
175
176	priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
177	if (!gpio_is_valid(priv->gpio))
178	return priv->gpio;
179
180	priv->active_low = flags & OF_GPIO_ACTIVE_LOW;
181
182	ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
183	if (ret)
184	return ret;
185	if (!strncmp(algo, "toggle", 6)) {
186	priv->hw_algo = HW_ALGO_TOGGLE;
187	f = GPIOF_IN;
188	} else if (!strncmp(algo, "level", 5)) {
189	priv->hw_algo = HW_ALGO_LEVEL;
190	f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
191	} else {
192	return -EINVAL;
193	}
194
195	ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,
196	dev_name(&pdev->dev));
197	if (ret)
198	return ret;
199
200	ret = of_property_read_u32(pdev->dev.of_node,
201	"hw_margin_ms", &hw_margin);
202	if (ret)
203	return ret;
204	/* Disallow values lower than 2 and higher than 65535 ms */
205	if (hw_margin < 2 \|\| hw_margin > 65535)
206	return -EINVAL;
207
208	/* Use safe value (1/2 of real timeout) */
209	priv->hw_margin = msecs_to_jiffies(hw_margin / 2);
210
ba804a95 ML	211	priv->always_running = of_property_read_bool(pdev->dev.of_node,
	212	"always-running");
	213
25134eaf AS	214	watchdog_set_drvdata(&priv->wdd, priv);
	215
	216	priv->wdd.info = &gpio_wdt_ident;
	217	priv->wdd.ops = &gpio_wdt_ops;
	218	priv->wdd.min_timeout = SOFT_TIMEOUT_MIN;
	219	priv->wdd.max_timeout = SOFT_TIMEOUT_MAX;
	220
	221	if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
	222	priv->wdd.timeout = SOFT_TIMEOUT_DEF;
	223
	224	setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
	225
	226	ret = watchdog_register_device(&priv->wdd);
	227	if (ret)
	228	return ret;
	229
	230	priv->notifier.notifier_call = gpio_wdt_notify_sys;
	231	ret = register_reboot_notifier(&priv->notifier);
	232	if (ret)
ba804a95	233	goto error_unregister;
25134eaf	234
ba804a95 ML	235	if (priv->always_running)
	236	gpio_wdt_start_impl(priv);
	237
	238	return 0;
	239
	240	error_unregister:
	241	watchdog_unregister_device(&priv->wdd);
25134eaf AS	242	return ret;
	243	}
	244
	245	static int gpio_wdt_remove(struct platform_device *pdev)
	246	{
	247	struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
	248
	249	del_timer_sync(&priv->timer);
	250	unregister_reboot_notifier(&priv->notifier);
	251	watchdog_unregister_device(&priv->wdd);
	252
	253	return 0;
	254	}
	255
	256	static const struct of_device_id gpio_wdt_dt_ids[] = {
	257	{ .compatible = "linux,wdt-gpio", },
	258	{ }
	259	};
	260	MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
	261
	262	static struct platform_driver gpio_wdt_driver = {
	263	.driver = {
	264	.name = "gpio-wdt",
25134eaf AS	265	.of_match_table = gpio_wdt_dt_ids,
	266	},
	267	.probe = gpio_wdt_probe,
	268	.remove = gpio_wdt_remove,
	269	};
	270	module_platform_driver(gpio_wdt_driver);
	271
	272	MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
	273	MODULE_DESCRIPTION("GPIO Watchdog");
	274	MODULE_LICENSE("GPL");