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