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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Driver for watchdog device controlled through GPIO-line
4 *
5 * Author: 2013, Alexander Shiyan <shc_work@mail.ru>
6 */
7
8#include <linux/delay.h>
9#include <linux/err.h>
10#include <linux/gpio/consumer.h>
11#include <linux/mod_devicetable.h>
12#include <linux/module.h>
13#include <linux/platform_device.h>
14#include <linux/property.h>
15#include <linux/watchdog.h>
16
17static bool nowayout = WATCHDOG_NOWAYOUT;
18module_param(nowayout, bool, 0);
19MODULE_PARM_DESC(nowayout,
20 "Watchdog cannot be stopped once started (default="
21 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
22
23#define SOFT_TIMEOUT_MIN 1
24#define SOFT_TIMEOUT_DEF 60
25
26enum {
27 HW_ALGO_TOGGLE,
28 HW_ALGO_LEVEL,
29};
30
31struct gpio_wdt_priv {
32 struct gpio_desc *gpiod;
33 bool state;
34 bool always_running;
35 unsigned int hw_algo;
36 struct watchdog_device wdd;
37};
38
39static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
40{
41 /* Eternal ping */
42 gpiod_set_value_cansleep(priv->gpiod, 1);
43
44 /* Put GPIO back to tristate */
45 if (priv->hw_algo == HW_ALGO_TOGGLE)
46 gpiod_direction_input(priv->gpiod);
47}
48
49static int gpio_wdt_ping(struct watchdog_device *wdd)
50{
51 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
52
53 switch (priv->hw_algo) {
54 case HW_ALGO_TOGGLE:
55 /* Toggle output pin */
56 priv->state = !priv->state;
57 gpiod_set_value_cansleep(priv->gpiod, priv->state);
58 break;
59 case HW_ALGO_LEVEL:
60 /* Pulse */
61 gpiod_set_value_cansleep(priv->gpiod, 1);
62 udelay(1);
63 gpiod_set_value_cansleep(priv->gpiod, 0);
64 break;
65 }
66 return 0;
67}
68
69static int gpio_wdt_start(struct watchdog_device *wdd)
70{
71 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
72
73 priv->state = 0;
74 gpiod_direction_output(priv->gpiod, priv->state);
75
76 set_bit(WDOG_HW_RUNNING, &wdd->status);
77
78 return gpio_wdt_ping(wdd);
79}
80
81static int gpio_wdt_stop(struct watchdog_device *wdd)
82{
83 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
84
85 if (!priv->always_running) {
86 gpio_wdt_disable(priv);
87 } else {
88 set_bit(WDOG_HW_RUNNING, &wdd->status);
89 }
90
91 return 0;
92}
93
94static const struct watchdog_info gpio_wdt_ident = {
95 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
96 WDIOF_SETTIMEOUT,
97 .identity = "GPIO Watchdog",
98};
99
100static const struct watchdog_ops gpio_wdt_ops = {
101 .owner = THIS_MODULE,
102 .start = gpio_wdt_start,
103 .stop = gpio_wdt_stop,
104 .ping = gpio_wdt_ping,
105};
106
107static int gpio_wdt_probe(struct platform_device *pdev)
108{
109 struct device *dev = &pdev->dev;
110 struct gpio_wdt_priv *priv;
111 enum gpiod_flags gflags;
112 unsigned int hw_margin;
113 const char *algo;
114 int ret;
115
116 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
117 if (!priv)
118 return -ENOMEM;
119
120 platform_set_drvdata(pdev, priv);
121
122 ret = device_property_read_string(dev, "hw_algo", &algo);
123 if (ret)
124 return ret;
125 if (!strcmp(algo, "toggle")) {
126 priv->hw_algo = HW_ALGO_TOGGLE;
127 gflags = GPIOD_IN;
128 } else if (!strcmp(algo, "level")) {
129 priv->hw_algo = HW_ALGO_LEVEL;
130 gflags = GPIOD_OUT_LOW;
131 } else {
132 return -EINVAL;
133 }
134
135 priv->gpiod = devm_gpiod_get(dev, NULL, gflags);
136 if (IS_ERR(priv->gpiod))
137 return PTR_ERR(priv->gpiod);
138
139 ret = device_property_read_u32(dev, "hw_margin_ms", &hw_margin);
140 if (ret)
141 return ret;
142 /* Disallow values lower than 2 and higher than 65535 ms */
143 if (hw_margin < 2 || hw_margin > 65535)
144 return -EINVAL;
145
146 priv->always_running = device_property_read_bool(dev, "always-running");
147
148 watchdog_set_drvdata(&priv->wdd, priv);
149
150 priv->wdd.info = &gpio_wdt_ident;
151 priv->wdd.ops = &gpio_wdt_ops;
152 priv->wdd.min_timeout = SOFT_TIMEOUT_MIN;
153 priv->wdd.max_hw_heartbeat_ms = hw_margin;
154 priv->wdd.parent = dev;
155 priv->wdd.timeout = SOFT_TIMEOUT_DEF;
156
157 watchdog_init_timeout(&priv->wdd, 0, dev);
158 watchdog_set_nowayout(&priv->wdd, nowayout);
159
160 watchdog_stop_on_reboot(&priv->wdd);
161
162 if (priv->always_running)
163 gpio_wdt_start(&priv->wdd);
164
165 return devm_watchdog_register_device(dev, &priv->wdd);
166}
167
168static const struct of_device_id gpio_wdt_dt_ids[] = {
169 { .compatible = "linux,wdt-gpio", },
170 { }
171};
172MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
173
174static struct platform_driver gpio_wdt_driver = {
175 .driver = {
176 .name = "gpio-wdt",
177 .of_match_table = gpio_wdt_dt_ids,
178 },
179 .probe = gpio_wdt_probe,
180};
181
182#ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
183static int __init gpio_wdt_init(void)
184{
185 return platform_driver_register(&gpio_wdt_driver);
186}
187arch_initcall(gpio_wdt_init);
188#else
189module_platform_driver(gpio_wdt_driver);
190#endif
191
192MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
193MODULE_DESCRIPTION("GPIO Watchdog");
194MODULE_LICENSE("GPL");
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/of_gpio.h>
16#include <linux/platform_device.h>
17#include <linux/watchdog.h>
18
19#define SOFT_TIMEOUT_MIN 1
20#define SOFT_TIMEOUT_DEF 60
21#define SOFT_TIMEOUT_MAX 0xffff
22
23enum {
24 HW_ALGO_TOGGLE,
25 HW_ALGO_LEVEL,
26};
27
28struct gpio_wdt_priv {
29 int gpio;
30 bool active_low;
31 bool state;
32 bool always_running;
33 bool armed;
34 unsigned int hw_algo;
35 unsigned int hw_margin;
36 unsigned long last_jiffies;
37 struct timer_list timer;
38 struct watchdog_device wdd;
39};
40
41static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
42{
43 gpio_set_value_cansleep(priv->gpio, !priv->active_low);
44
45 /* Put GPIO back to tristate */
46 if (priv->hw_algo == HW_ALGO_TOGGLE)
47 gpio_direction_input(priv->gpio);
48}
49
50static void gpio_wdt_hwping(unsigned long data)
51{
52 struct watchdog_device *wdd = (struct watchdog_device *)data;
53 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
54
55 if (priv->armed && time_after(jiffies, priv->last_jiffies +
56 msecs_to_jiffies(wdd->timeout * 1000))) {
57 dev_crit(wdd->parent,
58 "Timer expired. System will reboot soon!\n");
59 return;
60 }
61
62 /* Restart timer */
63 mod_timer(&priv->timer, jiffies + priv->hw_margin);
64
65 switch (priv->hw_algo) {
66 case HW_ALGO_TOGGLE:
67 /* Toggle output pin */
68 priv->state = !priv->state;
69 gpio_set_value_cansleep(priv->gpio, priv->state);
70 break;
71 case HW_ALGO_LEVEL:
72 /* Pulse */
73 gpio_set_value_cansleep(priv->gpio, !priv->active_low);
74 udelay(1);
75 gpio_set_value_cansleep(priv->gpio, priv->active_low);
76 break;
77 }
78}
79
80static void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)
81{
82 priv->state = priv->active_low;
83 gpio_direction_output(priv->gpio, priv->state);
84 priv->last_jiffies = jiffies;
85 gpio_wdt_hwping((unsigned long)&priv->wdd);
86}
87
88static int gpio_wdt_start(struct watchdog_device *wdd)
89{
90 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
91
92 gpio_wdt_start_impl(priv);
93 priv->armed = true;
94
95 return 0;
96}
97
98static int gpio_wdt_stop(struct watchdog_device *wdd)
99{
100 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
101
102 priv->armed = false;
103 if (!priv->always_running) {
104 mod_timer(&priv->timer, 0);
105 gpio_wdt_disable(priv);
106 }
107
108 return 0;
109}
110
111static int gpio_wdt_ping(struct watchdog_device *wdd)
112{
113 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
114
115 priv->last_jiffies = jiffies;
116
117 return 0;
118}
119
120static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
121{
122 wdd->timeout = t;
123
124 return gpio_wdt_ping(wdd);
125}
126
127static const struct watchdog_info gpio_wdt_ident = {
128 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
129 WDIOF_SETTIMEOUT,
130 .identity = "GPIO Watchdog",
131};
132
133static const struct watchdog_ops gpio_wdt_ops = {
134 .owner = THIS_MODULE,
135 .start = gpio_wdt_start,
136 .stop = gpio_wdt_stop,
137 .ping = gpio_wdt_ping,
138 .set_timeout = gpio_wdt_set_timeout,
139};
140
141static int gpio_wdt_probe(struct platform_device *pdev)
142{
143 struct gpio_wdt_priv *priv;
144 enum of_gpio_flags flags;
145 unsigned int hw_margin;
146 unsigned long f = 0;
147 const char *algo;
148 int ret;
149
150 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
151 if (!priv)
152 return -ENOMEM;
153
154 platform_set_drvdata(pdev, priv);
155
156 priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
157 if (!gpio_is_valid(priv->gpio))
158 return priv->gpio;
159
160 priv->active_low = flags & OF_GPIO_ACTIVE_LOW;
161
162 ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
163 if (ret)
164 return ret;
165 if (!strcmp(algo, "toggle")) {
166 priv->hw_algo = HW_ALGO_TOGGLE;
167 f = GPIOF_IN;
168 } else if (!strcmp(algo, "level")) {
169 priv->hw_algo = HW_ALGO_LEVEL;
170 f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
171 } else {
172 return -EINVAL;
173 }
174
175 ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,
176 dev_name(&pdev->dev));
177 if (ret)
178 return ret;
179
180 ret = of_property_read_u32(pdev->dev.of_node,
181 "hw_margin_ms", &hw_margin);
182 if (ret)
183 return ret;
184 /* Disallow values lower than 2 and higher than 65535 ms */
185 if (hw_margin < 2 || hw_margin > 65535)
186 return -EINVAL;
187
188 /* Use safe value (1/2 of real timeout) */
189 priv->hw_margin = msecs_to_jiffies(hw_margin / 2);
190
191 priv->always_running = of_property_read_bool(pdev->dev.of_node,
192 "always-running");
193
194 watchdog_set_drvdata(&priv->wdd, priv);
195
196 priv->wdd.info = &gpio_wdt_ident;
197 priv->wdd.ops = &gpio_wdt_ops;
198 priv->wdd.min_timeout = SOFT_TIMEOUT_MIN;
199 priv->wdd.max_timeout = SOFT_TIMEOUT_MAX;
200 priv->wdd.parent = &pdev->dev;
201
202 if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
203 priv->wdd.timeout = SOFT_TIMEOUT_DEF;
204
205 setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
206
207 watchdog_stop_on_reboot(&priv->wdd);
208
209 ret = watchdog_register_device(&priv->wdd);
210 if (ret)
211 return ret;
212
213 if (priv->always_running)
214 gpio_wdt_start_impl(priv);
215
216 return 0;
217}
218
219static int gpio_wdt_remove(struct platform_device *pdev)
220{
221 struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
222
223 del_timer_sync(&priv->timer);
224 watchdog_unregister_device(&priv->wdd);
225
226 return 0;
227}
228
229static const struct of_device_id gpio_wdt_dt_ids[] = {
230 { .compatible = "linux,wdt-gpio", },
231 { }
232};
233MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
234
235static struct platform_driver gpio_wdt_driver = {
236 .driver = {
237 .name = "gpio-wdt",
238 .of_match_table = gpio_wdt_dt_ids,
239 },
240 .probe = gpio_wdt_probe,
241 .remove = gpio_wdt_remove,
242};
243
244#ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
245static int __init gpio_wdt_init(void)
246{
247 return platform_driver_register(&gpio_wdt_driver);
248}
249arch_initcall(gpio_wdt_init);
250#else
251module_platform_driver(gpio_wdt_driver);
252#endif
253
254MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
255MODULE_DESCRIPTION("GPIO Watchdog");
256MODULE_LICENSE("GPL");