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_start_impl(struct gpio_wdt_priv *priv)
  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
  61 static int gpio_wdt_start(struct watchdog_device *wdd)
  62 {
  63         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
  64
  65         gpio_wdt_start_impl(priv);
  66         priv->armed = true;
  67
  68         return 0;
  69 }
  70
  71 static int gpio_wdt_stop(struct watchdog_device *wdd)
  72 {
  73         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
  74
  75         priv->armed = false;
  76         if (!priv->always_running) {
  77                 mod_timer(&priv->timer, 0);
  78                 gpio_wdt_disable(priv);
  79         }
  80
  81         return 0;
  82 }
  83
  84 static int gpio_wdt_ping(struct watchdog_device *wdd)
  85 {
  86         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
  87
  88         priv->last_jiffies = jiffies;
  89
  90         return 0;
  91 }
  92
  93 static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
  94 {
  95         wdd->timeout = t;
  96
  97         return gpio_wdt_ping(wdd);
  98 }
  99
 100 static void gpio_wdt_hwping(unsigned long data)
 101 {
 102         struct watchdog_device *wdd = (struct watchdog_device *)data;
 103         struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
 104
 105         if (priv->armed && time_after(jiffies, priv->last_jiffies +
 106                                       msecs_to_jiffies(wdd->timeout * 1000))) {
 107                 dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
 108                 return;
 109         }
 110
 111         /* Restart timer */
 112         mod_timer(&priv->timer, jiffies + priv->hw_margin);
 113
 114         switch (priv->hw_algo) {
 115         case HW_ALGO_TOGGLE:
 116                 /* Toggle output pin */
 117                 priv->state = !priv->state;
 118                 gpio_set_value_cansleep(priv->gpio, priv->state);
 119                 break;
 120         case HW_ALGO_LEVEL:
 121                 /* Pulse */
 122                 gpio_set_value_cansleep(priv->gpio, !priv->active_low);
 123                 udelay(1);
 124                 gpio_set_value_cansleep(priv->gpio, priv->active_low);
 125                 break;
 126         }
 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 (!strncmp(algo, "toggle", 6)) {
 186                 priv->hw_algo = HW_ALGO_TOGGLE;
 187                 f = GPIOF_IN;
 188         } else if (!strncmp(algo, "level", 5)) {
 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
 221         if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
 222                 priv->wdd.timeout = SOFT_TIMEOUT_DEF;
 223
 224         setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
 225
 226         ret = watchdog_register_device(&priv->wdd);
 227         if (ret)
 228                 return ret;
 229
 230         priv->notifier.notifier_call = gpio_wdt_notify_sys;
 231         ret = register_reboot_notifier(&priv->notifier);
 232         if (ret)
 233                 goto error_unregister;
 234
 235         if (priv->always_running)
 236                 gpio_wdt_start_impl(priv);
 237
 238         return 0;
 239
 240 error_unregister:
 241         watchdog_unregister_device(&priv->wdd);
 242         return ret;
 243 }
 244
 245 static int gpio_wdt_remove(struct platform_device *pdev)
 246 {
 247         struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
 248
 249         del_timer_sync(&priv->timer);
 250         unregister_reboot_notifier(&priv->notifier);
 251         watchdog_unregister_device(&priv->wdd);
 252
 253         return 0;
 254 }
 255
 256 static const struct of_device_id gpio_wdt_dt_ids[] = {
 257         { .compatible = "linux,wdt-gpio", },
 258         { }
 259 };
 260 MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
 261
 262 static struct platform_driver gpio_wdt_driver = {
 263         .driver = {
 264                 .name           = "gpio-wdt",
 265                 .of_match_table = gpio_wdt_dt_ids,
 266         },
 267         .probe  = gpio_wdt_probe,
 268         .remove = gpio_wdt_remove,
 269 };
 270 module_platform_driver(gpio_wdt_driver);
 271
 272 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
 273 MODULE_DESCRIPTION("GPIO Watchdog");
 274 MODULE_LICENSE("GPL");