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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/of_gpio.h>
 16 #include <linux/platform_device.h>
 17 #include <linux/watchdog.h>
 18 
 19 #define SOFT_TIMEOUT_MIN        1
 20 #define SOFT_TIMEOUT_DEF        60
 21 #define SOFT_TIMEOUT_MAX        0xffff
 22 
 23 enum {
 24         HW_ALGO_TOGGLE,
 25         HW_ALGO_LEVEL,
 26 };
 27 
 28 struct gpio_wdt_priv {
 29         int                     gpio;
 30         bool                    active_low;
 31         bool                    state;
 32         bool                    always_running;
 33         bool                    armed;
 34         unsigned int            hw_algo;
 35         unsigned int            hw_margin;
 36         unsigned long           last_jiffies;
 37         struct timer_list       timer;
 38         struct watchdog_device  wdd;
 39 };
 40 
 41 static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
 42 {
 43         gpio_set_value_cansleep(priv->gpio, !priv->active_low);
 44 
 45         /* Put GPIO back to tristate */
 46         if (priv->hw_algo == HW_ALGO_TOGGLE)
 47                 gpio_direction_input(priv->gpio);
 48 }
 49 
 50 static void gpio_wdt_hwping(unsigned long data)
 51 {
 52         struct watchdog_device *wdd = (struct watchdog_device *)data;
 53         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
 54 
 55         if (priv->armed && time_after(jiffies, priv->last_jiffies +
 56                                       msecs_to_jiffies(wdd->timeout * 1000))) {
 57                 dev_crit(wdd->parent,
 58                          "Timer expired. System will reboot soon!\n");
 59                 return;
 60         }
 61 
 62         /* Restart timer */
 63         mod_timer(&priv->timer, jiffies + priv->hw_margin);
 64 
 65         switch (priv->hw_algo) {
 66         case HW_ALGO_TOGGLE:
 67                 /* Toggle output pin */
 68                 priv->state = !priv->state;
 69                 gpio_set_value_cansleep(priv->gpio, priv->state);
 70                 break;
 71         case HW_ALGO_LEVEL:
 72                 /* Pulse */
 73                 gpio_set_value_cansleep(priv->gpio, !priv->active_low);
 74                 udelay(1);
 75                 gpio_set_value_cansleep(priv->gpio, priv->active_low);
 76                 break;
 77         }
 78 }
 79 
 80 static void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)
 81 {
 82         priv->state = priv->active_low;
 83         gpio_direction_output(priv->gpio, priv->state);
 84         priv->last_jiffies = jiffies;
 85         gpio_wdt_hwping((unsigned long)&priv->wdd);
 86 }
 87 
 88 static int gpio_wdt_start(struct watchdog_device *wdd)
 89 {
 90         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
 91 
 92         gpio_wdt_start_impl(priv);
 93         priv->armed = true;
 94 
 95         return 0;
 96 }
 97 
 98 static int gpio_wdt_stop(struct watchdog_device *wdd)
 99 {
100         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
101 
102         priv->armed = false;
103         if (!priv->always_running) {
104                 mod_timer(&priv->timer, 0);
105                 gpio_wdt_disable(priv);
106         }
107 
108         return 0;
109 }
110 
111 static int gpio_wdt_ping(struct watchdog_device *wdd)
112 {
113         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
114 
115         priv->last_jiffies = jiffies;
116 
117         return 0;
118 }
119 
120 static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
121 {
122         wdd->timeout = t;
123 
124         return gpio_wdt_ping(wdd);
125 }
126 
127 static const struct watchdog_info gpio_wdt_ident = {
128         .options        = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
129                           WDIOF_SETTIMEOUT,
130         .identity       = "GPIO Watchdog",
131 };
132 
133 static const struct watchdog_ops gpio_wdt_ops = {
134         .owner          = THIS_MODULE,
135         .start          = gpio_wdt_start,
136         .stop           = gpio_wdt_stop,
137         .ping           = gpio_wdt_ping,
138         .set_timeout    = gpio_wdt_set_timeout,
139 };
140 
141 static int gpio_wdt_probe(struct platform_device *pdev)
142 {
143         struct gpio_wdt_priv *priv;
144         enum of_gpio_flags flags;
145         unsigned int hw_margin;
146         unsigned long f = 0;
147         const char *algo;
148         int ret;
149 
150         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
151         if (!priv)
152                 return -ENOMEM;
153 
154         priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
155         if (!gpio_is_valid(priv->gpio))
156                 return priv->gpio;
157 
158         priv->active_low = flags & OF_GPIO_ACTIVE_LOW;
159 
160         ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
161         if (ret)
162                 return ret;
163         if (!strcmp(algo, "toggle")) {
164                 priv->hw_algo = HW_ALGO_TOGGLE;
165                 f = GPIOF_IN;
166         } else if (!strcmp(algo, "level")) {
167                 priv->hw_algo = HW_ALGO_LEVEL;
168                 f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
169         } else {
170                 return -EINVAL;
171         }
172 
173         ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,
174                                     dev_name(&pdev->dev));
175         if (ret)
176                 return ret;
177 
178         ret = of_property_read_u32(pdev->dev.of_node,
179                                    "hw_margin_ms", &hw_margin);
180         if (ret)
181                 return ret;
182         /* Disallow values lower than 2 and higher than 65535 ms */
183         if (hw_margin < 2 || hw_margin > 65535)
184                 return -EINVAL;
185 
186         /* Use safe value (1/2 of real timeout) */
187         priv->hw_margin = msecs_to_jiffies(hw_margin / 2);
188 
189         priv->always_running = of_property_read_bool(pdev->dev.of_node,
190                                                      "always-running");
191 
192         watchdog_set_drvdata(&priv->wdd, priv);
193 
194         priv->wdd.info          = &gpio_wdt_ident;
195         priv->wdd.ops           = &gpio_wdt_ops;
196         priv->wdd.min_timeout   = SOFT_TIMEOUT_MIN;
197         priv->wdd.max_timeout   = SOFT_TIMEOUT_MAX;
198         priv->wdd.parent        = &pdev->dev;
199 
200         if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
201                 priv->wdd.timeout = SOFT_TIMEOUT_DEF;
202 
203         setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
204 
205         watchdog_stop_on_reboot(&priv->wdd);
206 
207         ret = watchdog_register_device(&priv->wdd);
208         if (ret)
209                 return ret;
210 
211         if (priv->always_running)
212                 gpio_wdt_start_impl(priv);
213 
214         return 0;
215 }
216 
217 static int gpio_wdt_remove(struct platform_device *pdev)
218 {
219         struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
220 
221         del_timer_sync(&priv->timer);
222         watchdog_unregister_device(&priv->wdd);
223 
224         return 0;
225 }
226 
227 static const struct of_device_id gpio_wdt_dt_ids[] = {
228         { .compatible = "linux,wdt-gpio", },
229         { }
230 };
231 MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
232 
233 static struct platform_driver gpio_wdt_driver = {
234         .driver = {
235                 .name           = "gpio-wdt",
236                 .of_match_table = gpio_wdt_dt_ids,
237         },
238         .probe  = gpio_wdt_probe,
239         .remove = gpio_wdt_remove,
240 };
241 
242 #ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
243 static int __init gpio_wdt_init(void)
244 {
245         return platform_driver_register(&gpio_wdt_driver);
246 }
247 arch_initcall(gpio_wdt_init);
248 #else
249 module_platform_driver(gpio_wdt_driver);
250 #endif
251 
252 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
253 MODULE_DESCRIPTION("GPIO Watchdog");
254 MODULE_LICENSE("GPL");
255 

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