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25134eaf AS |
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/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; | |
34 | unsigned int hw_algo; | |
35 | unsigned int hw_margin; | |
36 | unsigned long last_jiffies; | |
37 | struct notifier_block notifier; | |
38 | struct timer_list timer; | |
39 | struct watchdog_device wdd; | |
40 | }; | |
41 | ||
42 | static void gpio_wdt_disable(struct gpio_wdt_priv *priv) | |
43 | { | |
44 | gpio_set_value_cansleep(priv->gpio, !priv->active_low); | |
45 | ||
46 | /* Put GPIO back to tristate */ | |
47 | if (priv->hw_algo == HW_ALGO_TOGGLE) | |
48 | gpio_direction_input(priv->gpio); | |
49 | } | |
50 | ||
51 | static int gpio_wdt_start(struct watchdog_device *wdd) | |
52 | { | |
53 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); | |
54 | ||
55 | priv->state = priv->active_low; | |
56 | gpio_direction_output(priv->gpio, priv->state); | |
57 | priv->last_jiffies = jiffies; | |
58 | mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin); | |
59 | ||
60 | return 0; | |
61 | } | |
62 | ||
63 | static int gpio_wdt_stop(struct watchdog_device *wdd) | |
64 | { | |
65 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); | |
66 | ||
67 | mod_timer(&priv->timer, 0); | |
68 | gpio_wdt_disable(priv); | |
69 | ||
70 | return 0; | |
71 | } | |
72 | ||
73 | static int gpio_wdt_ping(struct watchdog_device *wdd) | |
74 | { | |
75 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); | |
76 | ||
77 | priv->last_jiffies = jiffies; | |
78 | ||
79 | return 0; | |
80 | } | |
81 | ||
82 | static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t) | |
83 | { | |
84 | wdd->timeout = t; | |
85 | ||
86 | return gpio_wdt_ping(wdd); | |
87 | } | |
88 | ||
89 | static void gpio_wdt_hwping(unsigned long data) | |
90 | { | |
91 | struct watchdog_device *wdd = (struct watchdog_device *)data; | |
92 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); | |
93 | ||
94 | if (time_after(jiffies, priv->last_jiffies + | |
95 | msecs_to_jiffies(wdd->timeout * 1000))) { | |
96 | dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n"); | |
97 | return; | |
98 | } | |
99 | ||
100 | /* Restart timer */ | |
101 | mod_timer(&priv->timer, jiffies + priv->hw_margin); | |
102 | ||
103 | switch (priv->hw_algo) { | |
104 | case HW_ALGO_TOGGLE: | |
105 | /* Toggle output pin */ | |
106 | priv->state = !priv->state; | |
107 | gpio_set_value_cansleep(priv->gpio, priv->state); | |
108 | break; | |
109 | case HW_ALGO_LEVEL: | |
110 | /* Pulse */ | |
111 | gpio_set_value_cansleep(priv->gpio, !priv->active_low); | |
112 | udelay(1); | |
113 | gpio_set_value_cansleep(priv->gpio, priv->active_low); | |
114 | break; | |
115 | } | |
116 | } | |
117 | ||
118 | static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code, | |
119 | void *unused) | |
120 | { | |
121 | struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv, | |
122 | notifier); | |
123 | ||
124 | mod_timer(&priv->timer, 0); | |
125 | ||
126 | switch (code) { | |
127 | case SYS_HALT: | |
128 | case SYS_POWER_OFF: | |
129 | gpio_wdt_disable(priv); | |
130 | break; | |
131 | default: | |
132 | break; | |
133 | } | |
134 | ||
135 | return NOTIFY_DONE; | |
136 | } | |
137 | ||
138 | static const struct watchdog_info gpio_wdt_ident = { | |
139 | .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | | |
140 | WDIOF_SETTIMEOUT, | |
141 | .identity = "GPIO Watchdog", | |
142 | }; | |
143 | ||
144 | static const struct watchdog_ops gpio_wdt_ops = { | |
145 | .owner = THIS_MODULE, | |
146 | .start = gpio_wdt_start, | |
147 | .stop = gpio_wdt_stop, | |
148 | .ping = gpio_wdt_ping, | |
149 | .set_timeout = gpio_wdt_set_timeout, | |
150 | }; | |
151 | ||
152 | static int gpio_wdt_probe(struct platform_device *pdev) | |
153 | { | |
154 | struct gpio_wdt_priv *priv; | |
155 | enum of_gpio_flags flags; | |
156 | unsigned int hw_margin; | |
157 | unsigned long f = 0; | |
158 | const char *algo; | |
159 | int ret; | |
160 | ||
161 | priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); | |
162 | if (!priv) | |
163 | return -ENOMEM; | |
164 | ||
165 | priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags); | |
166 | if (!gpio_is_valid(priv->gpio)) | |
167 | return priv->gpio; | |
168 | ||
169 | priv->active_low = flags & OF_GPIO_ACTIVE_LOW; | |
170 | ||
171 | ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo); | |
172 | if (ret) | |
173 | return ret; | |
174 | if (!strncmp(algo, "toggle", 6)) { | |
175 | priv->hw_algo = HW_ALGO_TOGGLE; | |
176 | f = GPIOF_IN; | |
177 | } else if (!strncmp(algo, "level", 5)) { | |
178 | priv->hw_algo = HW_ALGO_LEVEL; | |
179 | f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW; | |
180 | } else { | |
181 | return -EINVAL; | |
182 | } | |
183 | ||
184 | ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f, | |
185 | dev_name(&pdev->dev)); | |
186 | if (ret) | |
187 | return ret; | |
188 | ||
189 | ret = of_property_read_u32(pdev->dev.of_node, | |
190 | "hw_margin_ms", &hw_margin); | |
191 | if (ret) | |
192 | return ret; | |
193 | /* Disallow values lower than 2 and higher than 65535 ms */ | |
194 | if (hw_margin < 2 || hw_margin > 65535) | |
195 | return -EINVAL; | |
196 | ||
197 | /* Use safe value (1/2 of real timeout) */ | |
198 | priv->hw_margin = msecs_to_jiffies(hw_margin / 2); | |
199 | ||
200 | watchdog_set_drvdata(&priv->wdd, priv); | |
201 | ||
202 | priv->wdd.info = &gpio_wdt_ident; | |
203 | priv->wdd.ops = &gpio_wdt_ops; | |
204 | priv->wdd.min_timeout = SOFT_TIMEOUT_MIN; | |
205 | priv->wdd.max_timeout = SOFT_TIMEOUT_MAX; | |
206 | ||
207 | if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0) | |
208 | priv->wdd.timeout = SOFT_TIMEOUT_DEF; | |
209 | ||
210 | setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd); | |
211 | ||
212 | ret = watchdog_register_device(&priv->wdd); | |
213 | if (ret) | |
214 | return ret; | |
215 | ||
216 | priv->notifier.notifier_call = gpio_wdt_notify_sys; | |
217 | ret = register_reboot_notifier(&priv->notifier); | |
218 | if (ret) | |
219 | watchdog_unregister_device(&priv->wdd); | |
220 | ||
221 | return ret; | |
222 | } | |
223 | ||
224 | static int gpio_wdt_remove(struct platform_device *pdev) | |
225 | { | |
226 | struct gpio_wdt_priv *priv = platform_get_drvdata(pdev); | |
227 | ||
228 | del_timer_sync(&priv->timer); | |
229 | unregister_reboot_notifier(&priv->notifier); | |
230 | watchdog_unregister_device(&priv->wdd); | |
231 | ||
232 | return 0; | |
233 | } | |
234 | ||
235 | static const struct of_device_id gpio_wdt_dt_ids[] = { | |
236 | { .compatible = "linux,wdt-gpio", }, | |
237 | { } | |
238 | }; | |
239 | MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids); | |
240 | ||
241 | static struct platform_driver gpio_wdt_driver = { | |
242 | .driver = { | |
243 | .name = "gpio-wdt", | |
25134eaf AS |
244 | .of_match_table = gpio_wdt_dt_ids, |
245 | }, | |
246 | .probe = gpio_wdt_probe, | |
247 | .remove = gpio_wdt_remove, | |
248 | }; | |
249 | module_platform_driver(gpio_wdt_driver); | |
250 | ||
251 | MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>"); | |
252 | MODULE_DESCRIPTION("GPIO Watchdog"); | |
253 | MODULE_LICENSE("GPL"); |