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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/gpio/consumer.h>
16#include <linux/of.h>
17#include <linux/platform_device.h>
18#include <linux/watchdog.h>
19
20#define SOFT_TIMEOUT_MIN 1
21#define SOFT_TIMEOUT_DEF 60
22
23enum {
24 HW_ALGO_TOGGLE,
25 HW_ALGO_LEVEL,
26};
27
28struct gpio_wdt_priv {
29 struct gpio_desc *gpiod;
30 bool state;
31 bool always_running;
32 unsigned int hw_algo;
33 struct watchdog_device wdd;
34};
35
36static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
37{
38 /* Eternal ping */
39 gpiod_set_value_cansleep(priv->gpiod, 1);
40
41 /* Put GPIO back to tristate */
42 if (priv->hw_algo == HW_ALGO_TOGGLE)
43 gpiod_direction_input(priv->gpiod);
44}
45
46static int gpio_wdt_ping(struct watchdog_device *wdd)
47{
48 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
49
50 switch (priv->hw_algo) {
51 case HW_ALGO_TOGGLE:
52 /* Toggle output pin */
53 priv->state = !priv->state;
54 gpiod_set_value_cansleep(priv->gpiod, priv->state);
55 break;
56 case HW_ALGO_LEVEL:
57 /* Pulse */
58 gpiod_set_value_cansleep(priv->gpiod, 1);
59 udelay(1);
60 gpiod_set_value_cansleep(priv->gpiod, 0);
61 break;
62 }
63 return 0;
64}
65
66static int gpio_wdt_start(struct watchdog_device *wdd)
67{
68 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
69
70 priv->state = 0;
71 gpiod_direction_output(priv->gpiod, priv->state);
72
73 set_bit(WDOG_HW_RUNNING, &wdd->status);
74
75 return gpio_wdt_ping(wdd);
76}
77
78static int gpio_wdt_stop(struct watchdog_device *wdd)
79{
80 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
81
82 if (!priv->always_running) {
83 gpio_wdt_disable(priv);
84 } else {
85 set_bit(WDOG_HW_RUNNING, &wdd->status);
86 }
87
88 return 0;
89}
90
91static const struct watchdog_info gpio_wdt_ident = {
92 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
93 WDIOF_SETTIMEOUT,
94 .identity = "GPIO Watchdog",
95};
96
97static const struct watchdog_ops gpio_wdt_ops = {
98 .owner = THIS_MODULE,
99 .start = gpio_wdt_start,
100 .stop = gpio_wdt_stop,
101 .ping = gpio_wdt_ping,
102};
103
104static int gpio_wdt_probe(struct platform_device *pdev)
105{
106 struct device *dev = &pdev->dev;
107 struct device_node *np = dev->of_node;
108 struct gpio_wdt_priv *priv;
109 enum gpiod_flags gflags;
110 unsigned int hw_margin;
111 const char *algo;
112 int ret;
113
114 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
115 if (!priv)
116 return -ENOMEM;
117
118 platform_set_drvdata(pdev, priv);
119
120 ret = of_property_read_string(np, "hw_algo", &algo);
121 if (ret)
122 return ret;
123 if (!strcmp(algo, "toggle")) {
124 priv->hw_algo = HW_ALGO_TOGGLE;
125 gflags = GPIOD_IN;
126 } else if (!strcmp(algo, "level")) {
127 priv->hw_algo = HW_ALGO_LEVEL;
128 gflags = GPIOD_OUT_LOW;
129 } else {
130 return -EINVAL;
131 }
132
133 priv->gpiod = devm_gpiod_get(dev, NULL, gflags);
134 if (IS_ERR(priv->gpiod))
135 return PTR_ERR(priv->gpiod);
136
137 ret = of_property_read_u32(np,
138 "hw_margin_ms", &hw_margin);
139 if (ret)
140 return ret;
141 /* Disallow values lower than 2 and higher than 65535 ms */
142 if (hw_margin < 2 || hw_margin > 65535)
143 return -EINVAL;
144
145 priv->always_running = of_property_read_bool(np,
146 "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, &pdev->dev);
158
159 watchdog_stop_on_reboot(&priv->wdd);
160
161 if (priv->always_running)
162 gpio_wdt_start(&priv->wdd);
163
164 ret = watchdog_register_device(&priv->wdd);
165
166 return ret;
167}
168
169static int gpio_wdt_remove(struct platform_device *pdev)
170{
171 struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
172
173 watchdog_unregister_device(&priv->wdd);
174
175 return 0;
176}
177
178static const struct of_device_id gpio_wdt_dt_ids[] = {
179 { .compatible = "linux,wdt-gpio", },
180 { }
181};
182MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
183
184static struct platform_driver gpio_wdt_driver = {
185 .driver = {
186 .name = "gpio-wdt",
187 .of_match_table = gpio_wdt_dt_ids,
188 },
189 .probe = gpio_wdt_probe,
190 .remove = gpio_wdt_remove,
191};
192
193#ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
194static int __init gpio_wdt_init(void)
195{
196 return platform_driver_register(&gpio_wdt_driver);
197}
198arch_initcall(gpio_wdt_init);
199#else
200module_platform_driver(gpio_wdt_driver);
201#endif
202
203MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
204MODULE_DESCRIPTION("GPIO Watchdog");
205MODULE_LICENSE("GPL");