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Linux/drivers/watchdog/gpio_wdt.c

  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         bool                    always_running;
 35         bool                    armed;
 36         unsigned int            hw_algo;
 37         unsigned int            hw_margin;
 38         unsigned long           last_jiffies;
 39         struct notifier_block   notifier;
 40         struct timer_list       timer;
 41         struct watchdog_device  wdd;
 42 };
 43 
 44 static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
 45 {
 46         gpio_set_value_cansleep(priv->gpio, !priv->active_low);
 47 
 48         /* Put GPIO back to tristate */
 49         if (priv->hw_algo == HW_ALGO_TOGGLE)
 50                 gpio_direction_input(priv->gpio);
 51 }
 52 
 53 static void gpio_wdt_hwping(unsigned long data)
 54 {
 55         struct watchdog_device *wdd = (struct watchdog_device *)data;
 56         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
 57 
 58         if (priv->armed && time_after(jiffies, priv->last_jiffies +
 59                                       msecs_to_jiffies(wdd->timeout * 1000))) {
 60                 dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
 61                 return;
 62         }
 63 
 64         /* Restart timer */
 65         mod_timer(&priv->timer, jiffies + priv->hw_margin);
 66 
 67         switch (priv->hw_algo) {
 68         case HW_ALGO_TOGGLE:
 69                 /* Toggle output pin */
 70                 priv->state = !priv->state;
 71                 gpio_set_value_cansleep(priv->gpio, priv->state);
 72                 break;
 73         case HW_ALGO_LEVEL:
 74                 /* Pulse */
 75                 gpio_set_value_cansleep(priv->gpio, !priv->active_low);
 76                 udelay(1);
 77                 gpio_set_value_cansleep(priv->gpio, priv->active_low);
 78                 break;
 79         }
 80 }
 81 
 82 static void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)
 83 {
 84         priv->state = priv->active_low;
 85         gpio_direction_output(priv->gpio, priv->state);
 86         priv->last_jiffies = jiffies;
 87         gpio_wdt_hwping((unsigned long)&priv->wdd);
 88 }
 89 
 90 static int gpio_wdt_start(struct watchdog_device *wdd)
 91 {
 92         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
 93 
 94         gpio_wdt_start_impl(priv);
 95         priv->armed = true;
 96 
 97         return 0;
 98 }
 99 
100 static int gpio_wdt_stop(struct watchdog_device *wdd)
101 {
102         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
103 
104         priv->armed = false;
105         if (!priv->always_running) {
106                 mod_timer(&priv->timer, 0);
107                 gpio_wdt_disable(priv);
108         }
109 
110         return 0;
111 }
112 
113 static int gpio_wdt_ping(struct watchdog_device *wdd)
114 {
115         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
116 
117         priv->last_jiffies = jiffies;
118 
119         return 0;
120 }
121 
122 static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
123 {
124         wdd->timeout = t;
125 
126         return gpio_wdt_ping(wdd);
127 }
128 
129 static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
130                                void *unused)
131 {
132         struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
133                                                   notifier);
134 
135         mod_timer(&priv->timer, 0);
136 
137         switch (code) {
138         case SYS_HALT:
139         case SYS_POWER_OFF:
140                 gpio_wdt_disable(priv);
141                 break;
142         default:
143                 break;
144         }
145 
146         return NOTIFY_DONE;
147 }
148 
149 static const struct watchdog_info gpio_wdt_ident = {
150         .options        = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
151                           WDIOF_SETTIMEOUT,
152         .identity       = "GPIO Watchdog",
153 };
154 
155 static const struct watchdog_ops gpio_wdt_ops = {
156         .owner          = THIS_MODULE,
157         .start          = gpio_wdt_start,
158         .stop           = gpio_wdt_stop,
159         .ping           = gpio_wdt_ping,
160         .set_timeout    = gpio_wdt_set_timeout,
161 };
162 
163 static int gpio_wdt_probe(struct platform_device *pdev)
164 {
165         struct gpio_wdt_priv *priv;
166         enum of_gpio_flags flags;
167         unsigned int hw_margin;
168         unsigned long f = 0;
169         const char *algo;
170         int ret;
171 
172         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
173         if (!priv)
174                 return -ENOMEM;
175 
176         priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
177         if (!gpio_is_valid(priv->gpio))
178                 return priv->gpio;
179 
180         priv->active_low = flags & OF_GPIO_ACTIVE_LOW;
181 
182         ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
183         if (ret)
184                 return ret;
185         if (!strcmp(algo, "toggle")) {
186                 priv->hw_algo = HW_ALGO_TOGGLE;
187                 f = GPIOF_IN;
188         } else if (!strcmp(algo, "level")) {
189                 priv->hw_algo = HW_ALGO_LEVEL;
190                 f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
191         } else {
192                 return -EINVAL;
193         }
194 
195         ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,
196                                     dev_name(&pdev->dev));
197         if (ret)
198                 return ret;
199 
200         ret = of_property_read_u32(pdev->dev.of_node,
201                                    "hw_margin_ms", &hw_margin);
202         if (ret)
203                 return ret;
204         /* Disallow values lower than 2 and higher than 65535 ms */
205         if (hw_margin < 2 || hw_margin > 65535)
206                 return -EINVAL;
207 
208         /* Use safe value (1/2 of real timeout) */
209         priv->hw_margin = msecs_to_jiffies(hw_margin / 2);
210 
211         priv->always_running = of_property_read_bool(pdev->dev.of_node,
212                                                      "always-running");
213 
214         watchdog_set_drvdata(&priv->wdd, priv);
215 
216         priv->wdd.info          = &gpio_wdt_ident;
217         priv->wdd.ops           = &gpio_wdt_ops;
218         priv->wdd.min_timeout   = SOFT_TIMEOUT_MIN;
219         priv->wdd.max_timeout   = SOFT_TIMEOUT_MAX;
220         priv->wdd.parent        = &pdev->dev;
221 
222         if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
223                 priv->wdd.timeout = SOFT_TIMEOUT_DEF;
224 
225         setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
226 
227         ret = watchdog_register_device(&priv->wdd);
228         if (ret)
229                 return ret;
230 
231         priv->notifier.notifier_call = gpio_wdt_notify_sys;
232         ret = register_reboot_notifier(&priv->notifier);
233         if (ret)
234                 goto error_unregister;
235 
236         if (priv->always_running)
237                 gpio_wdt_start_impl(priv);
238 
239         return 0;
240 
241 error_unregister:
242         watchdog_unregister_device(&priv->wdd);
243         return ret;
244 }
245 
246 static int gpio_wdt_remove(struct platform_device *pdev)
247 {
248         struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
249 
250         del_timer_sync(&priv->timer);
251         unregister_reboot_notifier(&priv->notifier);
252         watchdog_unregister_device(&priv->wdd);
253 
254         return 0;
255 }
256 
257 static const struct of_device_id gpio_wdt_dt_ids[] = {
258         { .compatible = "linux,wdt-gpio", },
259         { }
260 };
261 MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
262 
263 static struct platform_driver gpio_wdt_driver = {
264         .driver = {
265                 .name           = "gpio-wdt",
266                 .of_match_table = gpio_wdt_dt_ids,
267         },
268         .probe  = gpio_wdt_probe,
269         .remove = gpio_wdt_remove,
270 };
271 
272 #ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
273 static int __init gpio_wdt_init(void)
274 {
275         return platform_driver_register(&gpio_wdt_driver);
276 }
277 arch_initcall(gpio_wdt_init);
278 #else
279 module_platform_driver(gpio_wdt_driver);
280 #endif
281 
282 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
283 MODULE_DESCRIPTION("GPIO Watchdog");
284 MODULE_LICENSE("GPL");
285 

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