drivers/watchdog/at91rm9200_wdt.c

   1 /*
   2  * Watchdog driver for Atmel AT91RM9200 (Thunder)
   3  *
   4  *  Copyright (C) 2003 SAN People (Pty) Ltd
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/bitops.h>
  15 #include <linux/delay.h>
  16 #include <linux/errno.h>
  17 #include <linux/fs.h>
  18 #include <linux/init.h>
  19 #include <linux/io.h>
  20 #include <linux/kernel.h>
  21 #include <linux/mfd/syscon.h>
  22 #include <linux/mfd/syscon/atmel-st.h>
  23 #include <linux/miscdevice.h>
  24 #include <linux/module.h>
  25 #include <linux/moduleparam.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/reboot.h>
  28 #include <linux/regmap.h>
  29 #include <linux/types.h>
  30 #include <linux/watchdog.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/of.h>
  33 #include <linux/of_device.h>
  34
  35 #define WDT_DEFAULT_TIME        5       /* seconds */
  36 #define WDT_MAX_TIME            256     /* seconds */
  37
  38 static int wdt_time = WDT_DEFAULT_TIME;
  39 static bool nowayout = WATCHDOG_NOWAYOUT;
  40 static struct regmap *regmap_st;
  41
  42 module_param(wdt_time, int, 0);
  43 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  44                                 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  45
  46 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  47 module_param(nowayout, bool, 0);
  48 MODULE_PARM_DESC(nowayout,
  49                 "Watchdog cannot be stopped once started (default="
  50                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  51 #endif
  52
  53
  54 static unsigned long at91wdt_busy;
  55
  56 /* ......................................................................... */
  57
  58 static int at91rm9200_restart(struct notifier_block *this,
  59                                         unsigned long mode, void *cmd)
  60 {
  61         /*
  62          * Perform a hardware reset with the use of the Watchdog timer.
  63          */
  64         regmap_write(regmap_st, AT91_ST_WDMR,
  65                      AT91_ST_RSTEN | AT91_ST_EXTEN | 1);
  66         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
  67
  68         mdelay(2000);
  69
  70         pr_emerg("Unable to restart system\n");
  71         return NOTIFY_DONE;
  72 }
  73
  74 static struct notifier_block at91rm9200_restart_nb = {
  75         .notifier_call = at91rm9200_restart,
  76         .priority = 192,
  77 };
  78
  79 /*
  80  * Disable the watchdog.
  81  */
  82 static inline void at91_wdt_stop(void)
  83 {
  84         regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN);
  85 }
  86
  87 /*
  88  * Enable and reset the watchdog.
  89  */
  90 static inline void at91_wdt_start(void)
  91 {
  92         regmap_write(regmap_st, AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  93                                 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
  94         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
  95 }
  96
  97 /*
  98  * Reload the watchdog timer.  (ie, pat the watchdog)
  99  */
 100 static inline void at91_wdt_reload(void)
 101 {
 102         regmap_write(regmap_st, AT91_ST_CR, AT91_ST_WDRST);
 103 }
 104
 105 /* ......................................................................... */
 106
 107 /*
 108  * Watchdog device is opened, and watchdog starts running.
 109  */
 110 static int at91_wdt_open(struct inode *inode, struct file *file)
 111 {
 112         if (test_and_set_bit(0, &at91wdt_busy))
 113                 return -EBUSY;
 114
 115         at91_wdt_start();
 116         return nonseekable_open(inode, file);
 117 }
 118
 119 /*
 120  * Close the watchdog device.
 121  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
 122  *  disabled.
 123  */
 124 static int at91_wdt_close(struct inode *inode, struct file *file)
 125 {
 126         /* Disable the watchdog when file is closed */
 127         if (!nowayout)
 128                 at91_wdt_stop();
 129
 130         clear_bit(0, &at91wdt_busy);
 131         return 0;
 132 }
 133
 134 /*
 135  * Change the watchdog time interval.
 136  */
 137 static int at91_wdt_settimeout(int new_time)
 138 {
 139         /*
 140          * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
 141          *
 142          * Since WDV is a 16-bit counter, the maximum period is
 143          * 65536 / 256 = 256 seconds.
 144          */
 145         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 146                 return -EINVAL;
 147
 148         /* Set new watchdog time. It will be used when
 149            at91_wdt_start() is called. */
 150         wdt_time = new_time;
 151         return 0;
 152 }
 153
 154 static const struct watchdog_info at91_wdt_info = {
 155         .identity       = "at91 watchdog",
 156         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 157 };
 158
 159 /*
 160  * Handle commands from user-space.
 161  */
 162 static long at91_wdt_ioctl(struct file *file,
 163                                         unsigned int cmd, unsigned long arg)
 164 {
 165         void __user *argp = (void __user *)arg;
 166         int __user *p = argp;
 167         int new_value;
 168
 169         switch (cmd) {
 170         case WDIOC_GETSUPPORT:
 171                 return copy_to_user(argp, &at91_wdt_info,
 172                                 sizeof(at91_wdt_info)) ? -EFAULT : 0;
 173         case WDIOC_GETSTATUS:
 174         case WDIOC_GETBOOTSTATUS:
 175                 return put_user(0, p);
 176         case WDIOC_SETOPTIONS:
 177                 if (get_user(new_value, p))
 178                         return -EFAULT;
 179                 if (new_value & WDIOS_DISABLECARD)
 180                         at91_wdt_stop();
 181                 if (new_value & WDIOS_ENABLECARD)
 182                         at91_wdt_start();
 183                 return 0;
 184         case WDIOC_KEEPALIVE:
 185                 at91_wdt_reload();      /* pat the watchdog */
 186                 return 0;
 187         case WDIOC_SETTIMEOUT:
 188                 if (get_user(new_value, p))
 189                         return -EFAULT;
 190                 if (at91_wdt_settimeout(new_value))
 191                         return -EINVAL;
 192                 /* Enable new time value */
 193                 at91_wdt_start();
 194                 /* Return current value */
 195                 return put_user(wdt_time, p);
 196         case WDIOC_GETTIMEOUT:
 197                 return put_user(wdt_time, p);
 198         default:
 199                 return -ENOTTY;
 200         }
 201 }
 202
 203 /*
 204  * Pat the watchdog whenever device is written to.
 205  */
 206 static ssize_t at91_wdt_write(struct file *file, const char *data,
 207                                                 size_t len, loff_t *ppos)
 208 {
 209         at91_wdt_reload();              /* pat the watchdog */
 210         return len;
 211 }
 212
 213 /* ......................................................................... */
 214
 215 static const struct file_operations at91wdt_fops = {
 216         .owner          = THIS_MODULE,
 217         .llseek         = no_llseek,
 218         .unlocked_ioctl = at91_wdt_ioctl,
 219         .open           = at91_wdt_open,
 220         .release        = at91_wdt_close,
 221         .write          = at91_wdt_write,
 222 };
 223
 224 static struct miscdevice at91wdt_miscdev = {
 225         .minor          = WATCHDOG_MINOR,
 226         .name           = "watchdog",
 227         .fops           = &at91wdt_fops,
 228 };
 229
 230 static int at91wdt_probe(struct platform_device *pdev)
 231 {
 232         struct device *dev = &pdev->dev;
 233         struct device *parent;
 234         int res;
 235
 236         if (at91wdt_miscdev.parent)
 237                 return -EBUSY;
 238         at91wdt_miscdev.parent = &pdev->dev;
 239
 240         parent = dev->parent;
 241         if (!parent) {
 242                 dev_err(dev, "no parent\n");
 243                 return -ENODEV;
 244         }
 245
 246         regmap_st = syscon_node_to_regmap(parent->of_node);
 247         if (IS_ERR(regmap_st))
 248                 return -ENODEV;
 249
 250         res = misc_register(&at91wdt_miscdev);
 251         if (res)
 252                 return res;
 253
 254         res = register_restart_handler(&at91rm9200_restart_nb);
 255         if (res)
 256                 dev_warn(dev, "failed to register restart handler\n");
 257
 258         pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
 259                 wdt_time, nowayout ? ", nowayout" : "");
 260         return 0;
 261 }
 262
 263 static int at91wdt_remove(struct platform_device *pdev)
 264 {
 265         struct device *dev = &pdev->dev;
 266         int res;
 267
 268         res = unregister_restart_handler(&at91rm9200_restart_nb);
 269         if (res)
 270                 dev_warn(dev, "failed to unregister restart handler\n");
 271
 272         misc_deregister(&at91wdt_miscdev);
 273         at91wdt_miscdev.parent = NULL;
 274
 275         return res;
 276 }
 277
 278 static void at91wdt_shutdown(struct platform_device *pdev)
 279 {
 280         at91_wdt_stop();
 281 }
 282
 283 #ifdef CONFIG_PM
 284
 285 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
 286 {
 287         at91_wdt_stop();
 288         return 0;
 289 }
 290
 291 static int at91wdt_resume(struct platform_device *pdev)
 292 {
 293         if (at91wdt_busy)
 294                 at91_wdt_start();
 295         return 0;
 296 }
 297
 298 #else
 299 #define at91wdt_suspend NULL
 300 #define at91wdt_resume  NULL
 301 #endif
 302
 303 static const struct of_device_id at91_wdt_dt_ids[] = {
 304         { .compatible = "atmel,at91rm9200-wdt" },
 305         { /* sentinel */ }
 306 };
 307 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
 308
 309 static struct platform_driver at91wdt_driver = {
 310         .probe          = at91wdt_probe,
 311         .remove         = at91wdt_remove,
 312         .shutdown       = at91wdt_shutdown,
 313         .suspend        = at91wdt_suspend,
 314         .resume         = at91wdt_resume,
 315         .driver         = {
 316                 .name   = "atmel_st_watchdog",
 317                 .of_match_table = at91_wdt_dt_ids,
 318         },
 319 };
 320
 321 static int __init at91_wdt_init(void)
 322 {
 323         /* Check that the heartbeat value is within range;
 324            if not reset to the default */
 325         if (at91_wdt_settimeout(wdt_time)) {
 326                 at91_wdt_settimeout(WDT_DEFAULT_TIME);
 327                 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
 328                         wdt_time);
 329         }
 330
 331         return platform_driver_register(&at91wdt_driver);
 332 }
 333
 334 static void __exit at91_wdt_exit(void)
 335 {
 336         platform_driver_unregister(&at91wdt_driver);
 337 }
 338
 339 module_init(at91_wdt_init);
 340 module_exit(at91_wdt_exit);
 341
 342 MODULE_AUTHOR("Andrew Victor");
 343 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
 344 MODULE_LICENSE("GPL");
 345 MODULE_ALIAS("platform:atmel_st_watchdog");