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");