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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         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",
244                 .owner          = THIS_MODULE,
245                 .of_match_table = gpio_wdt_dt_ids,
246         },
247         .probe  = gpio_wdt_probe,
248         .remove = gpio_wdt_remove,
249 };
250 module_platform_driver(gpio_wdt_driver);
251 
252 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
253 MODULE_DESCRIPTION("GPIO Watchdog");
254 MODULE_LICENSE("GPL");
255 

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