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/errno.h>
  16 #include <linux/fs.h>
  17 #include <linux/init.h>
  18 #include <linux/io.h>
  19 #include <linux/kernel.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/types.h>
  25 #include <linux/watchdog.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/of.h>
  28 #include <linux/of_device.h>
  29 #include <mach/at91_st.h>
  30
  31 #define WDT_DEFAULT_TIME        5       /* seconds */
  32 #define WDT_MAX_TIME            256     /* seconds */
  33
  34 static int wdt_time = WDT_DEFAULT_TIME;
  35 static bool nowayout = WATCHDOG_NOWAYOUT;
  36
  37 module_param(wdt_time, int, 0);
  38 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  39                                 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  40
  41 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  42 module_param(nowayout, bool, 0);
  43 MODULE_PARM_DESC(nowayout,
  44                 "Watchdog cannot be stopped once started (default="
  45                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  46 #endif
  47
  48
  49 static unsigned long at91wdt_busy;
  50
  51 /* ......................................................................... */
  52
  53 /*
  54  * Disable the watchdog.
  55  */
  56 static inline void at91_wdt_stop(void)
  57 {
  58         at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN);
  59 }
  60
  61 /*
  62  * Enable and reset the watchdog.
  63  */
  64 static inline void at91_wdt_start(void)
  65 {
  66         at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  67                                 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
  68         at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
  69 }
  70
  71 /*
  72  * Reload the watchdog timer.  (ie, pat the watchdog)
  73  */
  74 static inline void at91_wdt_reload(void)
  75 {
  76         at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
  77 }
  78
  79 /* ......................................................................... */
  80
  81 /*
  82  * Watchdog device is opened, and watchdog starts running.
  83  */
  84 static int at91_wdt_open(struct inode *inode, struct file *file)
  85 {
  86         if (test_and_set_bit(0, &at91wdt_busy))
  87                 return -EBUSY;
  88
  89         at91_wdt_start();
  90         return nonseekable_open(inode, file);
  91 }
  92
  93 /*
  94  * Close the watchdog device.
  95  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
  96  *  disabled.
  97  */
  98 static int at91_wdt_close(struct inode *inode, struct file *file)
  99 {
 100         /* Disable the watchdog when file is closed */
 101         if (!nowayout)
 102                 at91_wdt_stop();
 103
 104         clear_bit(0, &at91wdt_busy);
 105         return 0;
 106 }
 107
 108 /*
 109  * Change the watchdog time interval.
 110  */
 111 static int at91_wdt_settimeout(int new_time)
 112 {
 113         /*
 114          * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
 115          *
 116          * Since WDV is a 16-bit counter, the maximum period is
 117          * 65536 / 256 = 256 seconds.
 118          */
 119         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 120                 return -EINVAL;
 121
 122         /* Set new watchdog time. It will be used when
 123            at91_wdt_start() is called. */
 124         wdt_time = new_time;
 125         return 0;
 126 }
 127
 128 static const struct watchdog_info at91_wdt_info = {
 129         .identity       = "at91 watchdog",
 130         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 131 };
 132
 133 /*
 134  * Handle commands from user-space.
 135  */
 136 static long at91_wdt_ioctl(struct file *file,
 137                                         unsigned int cmd, unsigned long arg)
 138 {
 139         void __user *argp = (void __user *)arg;
 140         int __user *p = argp;
 141         int new_value;
 142
 143         switch (cmd) {
 144         case WDIOC_GETSUPPORT:
 145                 return copy_to_user(argp, &at91_wdt_info,
 146                                 sizeof(at91_wdt_info)) ? -EFAULT : 0;
 147         case WDIOC_GETSTATUS:
 148         case WDIOC_GETBOOTSTATUS:
 149                 return put_user(0, p);
 150         case WDIOC_SETOPTIONS:
 151                 if (get_user(new_value, p))
 152                         return -EFAULT;
 153                 if (new_value & WDIOS_DISABLECARD)
 154                         at91_wdt_stop();
 155                 if (new_value & WDIOS_ENABLECARD)
 156                         at91_wdt_start();
 157                 return 0;
 158         case WDIOC_KEEPALIVE:
 159                 at91_wdt_reload();      /* pat the watchdog */
 160                 return 0;
 161         case WDIOC_SETTIMEOUT:
 162                 if (get_user(new_value, p))
 163                         return -EFAULT;
 164                 if (at91_wdt_settimeout(new_value))
 165                         return -EINVAL;
 166                 /* Enable new time value */
 167                 at91_wdt_start();
 168                 /* Return current value */
 169                 return put_user(wdt_time, p);
 170         case WDIOC_GETTIMEOUT:
 171                 return put_user(wdt_time, p);
 172         default:
 173                 return -ENOTTY;
 174         }
 175 }
 176
 177 /*
 178  * Pat the watchdog whenever device is written to.
 179  */
 180 static ssize_t at91_wdt_write(struct file *file, const char *data,
 181                                                 size_t len, loff_t *ppos)
 182 {
 183         at91_wdt_reload();              /* pat the watchdog */
 184         return len;
 185 }
 186
 187 /* ......................................................................... */
 188
 189 static const struct file_operations at91wdt_fops = {
 190         .owner          = THIS_MODULE,
 191         .llseek         = no_llseek,
 192         .unlocked_ioctl = at91_wdt_ioctl,
 193         .open           = at91_wdt_open,
 194         .release        = at91_wdt_close,
 195         .write          = at91_wdt_write,
 196 };
 197
 198 static struct miscdevice at91wdt_miscdev = {
 199         .minor          = WATCHDOG_MINOR,
 200         .name           = "watchdog",
 201         .fops           = &at91wdt_fops,
 202 };
 203
 204 static int at91wdt_probe(struct platform_device *pdev)
 205 {
 206         int res;
 207
 208         if (at91wdt_miscdev.parent)
 209                 return -EBUSY;
 210         at91wdt_miscdev.parent = &pdev->dev;
 211
 212         res = misc_register(&at91wdt_miscdev);
 213         if (res)
 214                 return res;
 215
 216         pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
 217                 wdt_time, nowayout ? ", nowayout" : "");
 218         return 0;
 219 }
 220
 221 static int at91wdt_remove(struct platform_device *pdev)
 222 {
 223         int res;
 224
 225         res = misc_deregister(&at91wdt_miscdev);
 226         if (!res)
 227                 at91wdt_miscdev.parent = NULL;
 228
 229         return res;
 230 }
 231
 232 static void at91wdt_shutdown(struct platform_device *pdev)
 233 {
 234         at91_wdt_stop();
 235 }
 236
 237 #ifdef CONFIG_PM
 238
 239 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
 240 {
 241         at91_wdt_stop();
 242         return 0;
 243 }
 244
 245 static int at91wdt_resume(struct platform_device *pdev)
 246 {
 247         if (at91wdt_busy)
 248                 at91_wdt_start();
 249         return 0;
 250 }
 251
 252 #else
 253 #define at91wdt_suspend NULL
 254 #define at91wdt_resume  NULL
 255 #endif
 256
 257 static const struct of_device_id at91_wdt_dt_ids[] = {
 258         { .compatible = "atmel,at91rm9200-wdt" },
 259         { /* sentinel */ }
 260 };
 261 MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
 262
 263 static struct platform_driver at91wdt_driver = {
 264         .probe          = at91wdt_probe,
 265         .remove         = at91wdt_remove,
 266         .shutdown       = at91wdt_shutdown,
 267         .suspend        = at91wdt_suspend,
 268         .resume         = at91wdt_resume,
 269         .driver         = {
 270                 .name   = "at91_wdt",
 271                 .owner  = THIS_MODULE,
 272                 .of_match_table = at91_wdt_dt_ids,
 273         },
 274 };
 275
 276 static int __init at91_wdt_init(void)
 277 {
 278         /* Check that the heartbeat value is within range;
 279            if not reset to the default */
 280         if (at91_wdt_settimeout(wdt_time)) {
 281                 at91_wdt_settimeout(WDT_DEFAULT_TIME);
 282                 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
 283                         wdt_time);
 284         }
 285
 286         return platform_driver_register(&at91wdt_driver);
 287 }
 288
 289 static void __exit at91_wdt_exit(void)
 290 {
 291         platform_driver_unregister(&at91wdt_driver);
 292 }
 293
 294 module_init(at91_wdt_init);
 295 module_exit(at91_wdt_exit);
 296
 297 MODULE_AUTHOR("Andrew Victor");
 298 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
 299 MODULE_LICENSE("GPL");
 300 MODULE_ALIAS("platform:at91_wdt");