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
23 enum {
24 HW_ALGO_TOGGLE,
25 HW_ALGO_LEVEL,
26 };
27
28 struct 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
gpio_wdt_disable(struct gpio_wdt_priv * priv)36 static 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
gpio_wdt_ping(struct watchdog_device * wdd)46 static 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
gpio_wdt_start(struct watchdog_device * wdd)66 static 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
gpio_wdt_stop(struct watchdog_device * wdd)78 static 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
91 static const struct watchdog_info gpio_wdt_ident = {
92 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
93 WDIOF_SETTIMEOUT,
94 .identity = "GPIO Watchdog",
95 };
96
97 static 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
gpio_wdt_probe(struct platform_device * pdev)104 static 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
gpio_wdt_remove(struct platform_device * pdev)169 static 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
178 static const struct of_device_id gpio_wdt_dt_ids[] = {
179 { .compatible = "linux,wdt-gpio", },
180 { }
181 };
182 MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
183
184 static 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
gpio_wdt_init(void)194 static int __init gpio_wdt_init(void)
195 {
196 return platform_driver_register(&gpio_wdt_driver);
197 }
198 arch_initcall(gpio_wdt_init);
199 #else
200 module_platform_driver(gpio_wdt_driver);
201 #endif
202
203 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
204 MODULE_DESCRIPTION("GPIO Watchdog");
205 MODULE_LICENSE("GPL");
206
