[linux.git] / drivers / watchdog / gpio_wdt.c

/*
 * Driver for watchdog device controlled through GPIO-line
 *
 * Author: 2013, Alexander Shiyan <[email protected]>
 *
 * 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_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 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;
	gpio_wdt_hwping((unsigned long)&priv->wdd);
}

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 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 (!strcmp(algo, "toggle")) {
		priv->hw_algo = HW_ALGO_TOGGLE;
		f = GPIOF_IN;
	} else if (!strcmp(algo, "level")) {
		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;
	priv->wdd.parent	= &pdev->dev;

	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,
};

#ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
static int __init gpio_wdt_init(void)
{
	return platform_driver_register(&gpio_wdt_driver);
}
arch_initcall(gpio_wdt_init);
#else
module_platform_driver(gpio_wdt_driver);
#endif

MODULE_AUTHOR("Alexander Shiyan <[email protected]>");
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 <[email protected]>
	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
4f2d0b2d UKK	53	static void gpio_wdt_hwping(unsigned long data)
	54	{
	55	struct watchdog_device wdd = (struct watchdog_device )data;
	56	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
	57
	58	if (priv->armed && time_after(jiffies, priv->last_jiffies +
	59	msecs_to_jiffies(wdd->timeout * 1000))) {
	60	dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
	61	return;
	62	}
	63
	64	/* Restart timer */
	65	mod_timer(&priv->timer, jiffies + priv->hw_margin);
	66
	67	switch (priv->hw_algo) {
	68	case HW_ALGO_TOGGLE:
	69	/* Toggle output pin */
	70	priv->state = !priv->state;
	71	gpio_set_value_cansleep(priv->gpio, priv->state);
	72	break;
	73	case HW_ALGO_LEVEL:
	74	/* Pulse */
	75	gpio_set_value_cansleep(priv->gpio, !priv->active_low);
	76	udelay(1);
	77	gpio_set_value_cansleep(priv->gpio, priv->active_low);
	78	break;
	79	}
	80	}
	81
ba804a95	82	static void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)
25134eaf	83	{
25134eaf AS	84	priv->state = priv->active_low;
	85	gpio_direction_output(priv->gpio, priv->state);
	86	priv->last_jiffies = jiffies;
4f2d0b2d	87	gpio_wdt_hwping((unsigned long)&priv->wdd);
ba804a95 ML	88	}
	89
	90	static int gpio_wdt_start(struct watchdog_device *wdd)
	91	{
	92	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
	93
	94	gpio_wdt_start_impl(priv);
	95	priv->armed = true;
25134eaf AS	96
	97	return 0;
	98	}
	99
	100	static int gpio_wdt_stop(struct watchdog_device *wdd)
	101	{
	102	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
	103
ba804a95 ML	104	priv->armed = false;
	105	if (!priv->always_running) {
	106	mod_timer(&priv->timer, 0);
	107	gpio_wdt_disable(priv);
	108	}
25134eaf AS	109
	110	return 0;
	111	}
	112
	113	static int gpio_wdt_ping(struct watchdog_device *wdd)
	114	{
	115	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
	116
	117	priv->last_jiffies = jiffies;
	118
	119	return 0;
	120	}
	121
	122	static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
	123	{
	124	wdd->timeout = t;
	125
	126	return gpio_wdt_ping(wdd);
	127	}
	128
25134eaf AS	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;
0a0a542f	185	if (!strcmp(algo, "toggle")) {
25134eaf AS	186	priv->hw_algo = HW_ALGO_TOGGLE;
25134eaf AS	187	f = GPIOF_IN;
0a0a542f	188	} else if (!strcmp(algo, "level")) {
25134eaf AS	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;
6551881c	220	priv->wdd.parent = &pdev->dev;
25134eaf AS	221
	222	if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
	223	priv->wdd.timeout = SOFT_TIMEOUT_DEF;
	224
	225	setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
	226
	227	ret = watchdog_register_device(&priv->wdd);
	228	if (ret)
	229	return ret;
	230
	231	priv->notifier.notifier_call = gpio_wdt_notify_sys;
	232	ret = register_reboot_notifier(&priv->notifier);
	233	if (ret)
ba804a95	234	goto error_unregister;
25134eaf	235
ba804a95 ML	236	if (priv->always_running)
	237	gpio_wdt_start_impl(priv);
	238
	239	return 0;
	240
	241	error_unregister:
	242	watchdog_unregister_device(&priv->wdd);
25134eaf AS	243	return ret;
	244	}
	245
	246	static int gpio_wdt_remove(struct platform_device *pdev)
	247	{
	248	struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
	249
	250	del_timer_sync(&priv->timer);
	251	unregister_reboot_notifier(&priv->notifier);
	252	watchdog_unregister_device(&priv->wdd);
	253
	254	return 0;
	255	}
	256
	257	static const struct of_device_id gpio_wdt_dt_ids[] = {
	258	{ .compatible = "linux,wdt-gpio", },
	259	{ }
	260	};
	261	MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
	262
	263	static struct platform_driver gpio_wdt_driver = {
	264	.driver = {
	265	.name = "gpio-wdt",
25134eaf AS	266	.of_match_table = gpio_wdt_dt_ids,
	267	},
	268	.probe = gpio_wdt_probe,
	269	.remove = gpio_wdt_remove,
	270	};
5e53c8ed JBT	271
	272	#ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
	273	static int __init gpio_wdt_init(void)
	274	{
	275	return platform_driver_register(&gpio_wdt_driver);
	276	}
	277	arch_initcall(gpio_wdt_init);
	278	#else
25134eaf	279	module_platform_driver(gpio_wdt_driver);
5e53c8ed	280	#endif
25134eaf AS	281
	282	MODULE_AUTHOR("Alexander Shiyan <[email protected]>");
	283	MODULE_DESCRIPTION("GPIO Watchdog");
	284	MODULE_LICENSE("GPL");