summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/gpio_wdt.c
blob: bc24674b4d9e1a5dd079640431d977472f7a8226 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
/*
 * 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/gpio/consumer.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>

#define SOFT_TIMEOUT_MIN	1
#define SOFT_TIMEOUT_DEF	60

enum {
	HW_ALGO_TOGGLE,
	HW_ALGO_LEVEL,
};

struct gpio_wdt_priv {
	struct gpio_desc	*gpiod;
	bool			state;
	bool			always_running;
	unsigned int		hw_algo;
	struct watchdog_device	wdd;
};

static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
{
	/* Eternal ping */
	gpiod_set_value_cansleep(priv->gpiod, 1);

	/* Put GPIO back to tristate */
	if (priv->hw_algo == HW_ALGO_TOGGLE)
		gpiod_direction_input(priv->gpiod);
}

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

	switch (priv->hw_algo) {
	case HW_ALGO_TOGGLE:
		/* Toggle output pin */
		priv->state = !priv->state;
		gpiod_set_value_cansleep(priv->gpiod, priv->state);
		break;
	case HW_ALGO_LEVEL:
		/* Pulse */
		gpiod_set_value_cansleep(priv->gpiod, 1);
		udelay(1);
		gpiod_set_value_cansleep(priv->gpiod, 0);
		break;
	}
	return 0;
}

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

	priv->state = 0;
	gpiod_direction_output(priv->gpiod, priv->state);

	set_bit(WDOG_HW_RUNNING, &wdd->status);

	return gpio_wdt_ping(wdd);
}

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

	if (!priv->always_running) {
		gpio_wdt_disable(priv);
	} else {
		set_bit(WDOG_HW_RUNNING, &wdd->status);
	}

	return 0;
}

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,
};

static int gpio_wdt_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct gpio_wdt_priv *priv;
	enum gpiod_flags gflags;
	unsigned int hw_margin;
	const char *algo;
	int ret;

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	platform_set_drvdata(pdev, priv);

	ret = of_property_read_string(np, "hw_algo", &algo);
	if (ret)
		return ret;
	if (!strcmp(algo, "toggle")) {
		priv->hw_algo = HW_ALGO_TOGGLE;
		gflags = GPIOD_IN;
	} else if (!strcmp(algo, "level")) {
		priv->hw_algo = HW_ALGO_LEVEL;
		gflags = GPIOD_OUT_LOW;
	} else {
		return -EINVAL;
	}

	priv->gpiod = devm_gpiod_get(dev, NULL, gflags);
	if (IS_ERR(priv->gpiod))
		return PTR_ERR(priv->gpiod);

	ret = of_property_read_u32(np,
				   "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;

	priv->always_running = of_property_read_bool(np,
						     "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_hw_heartbeat_ms = hw_margin;
	priv->wdd.parent	= dev;
	priv->wdd.timeout	= SOFT_TIMEOUT_DEF;

	watchdog_init_timeout(&priv->wdd, 0, dev);

	watchdog_stop_on_reboot(&priv->wdd);

	if (priv->always_running)
		gpio_wdt_start(&priv->wdd);

	return devm_watchdog_register_device(dev, &priv->wdd);
}

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,
};

#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 <shc_work@mail.ru>");
MODULE_DESCRIPTION("GPIO Watchdog");
MODULE_LICENSE("GPL");