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 #include <linux/bitops.h>
  13 #include <linux/errno.h>
  14 #include <linux/fs.h>
  15 #include <linux/init.h>
  16 #include <linux/io.h>
  17 #include <linux/kernel.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/types.h>
  23 #include <linux/watchdog.h>
  24 #include <linux/uaccess.h>
  25 #include <mach/at91_st.h>
  26
  27 #define WDT_DEFAULT_TIME        5       /* seconds */
  28 #define WDT_MAX_TIME            256     /* seconds */
  29
  30 static int wdt_time = WDT_DEFAULT_TIME;
  31 static int nowayout = WATCHDOG_NOWAYOUT;
  32
  33 module_param(wdt_time, int, 0);
  34 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  35                                 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  36
  37 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  38 module_param(nowayout, int, 0);
  39 MODULE_PARM_DESC(nowayout,
  40                 "Watchdog cannot be stopped once started (default="
  41                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  42 #endif
  43
  44
  45 static unsigned long at91wdt_busy;
  46
  47 /* ......................................................................... */
  48
  49 /*
  50  * Disable the watchdog.
  51  */
  52 static inline void at91_wdt_stop(void)
  53 {
  54         at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
  55 }
  56
  57 /*
  58  * Enable and reset the watchdog.
  59  */
  60 static inline void at91_wdt_start(void)
  61 {
  62         at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  63                                 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
  64         at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
  65 }
  66
  67 /*
  68  * Reload the watchdog timer.  (ie, pat the watchdog)
  69  */
  70 static inline void at91_wdt_reload(void)
  71 {
  72         at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
  73 }
  74
  75 /* ......................................................................... */
  76
  77 /*
  78  * Watchdog device is opened, and watchdog starts running.
  79  */
  80 static int at91_wdt_open(struct inode *inode, struct file *file)
  81 {
  82         if (test_and_set_bit(0, &at91wdt_busy))
  83                 return -EBUSY;
  84
  85         at91_wdt_start();
  86         return nonseekable_open(inode, file);
  87 }
  88
  89 /*
  90  * Close the watchdog device.
  91  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
  92  *  disabled.
  93  */
  94 static int at91_wdt_close(struct inode *inode, struct file *file)
  95 {
  96         /* Disable the watchdog when file is closed */
  97         if (!nowayout)
  98                 at91_wdt_stop();
  99
 100         clear_bit(0, &at91wdt_busy);
 101         return 0;
 102 }
 103
 104 /*
 105  * Change the watchdog time interval.
 106  */
 107 static int at91_wdt_settimeout(int new_time)
 108 {
 109         /*
 110          * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
 111          *
 112          * Since WDV is a 16-bit counter, the maximum period is
 113          * 65536 / 256 = 256 seconds.
 114          */
 115         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 116                 return -EINVAL;
 117
 118         /* Set new watchdog time. It will be used when
 119            at91_wdt_start() is called. */
 120         wdt_time = new_time;
 121         return 0;
 122 }
 123
 124 static struct watchdog_info at91_wdt_info = {
 125         .identity       = "at91 watchdog",
 126         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 127 };
 128
 129 /*
 130  * Handle commands from user-space.
 131  */
 132 static long at91_wdt_ioctl(struct file *file,
 133                                         unsigned int cmd, unsigned long arg)
 134 {
 135         void __user *argp = (void __user *)arg;
 136         int __user *p = argp;
 137         int new_value;
 138
 139         switch (cmd) {
 140         case WDIOC_GETSUPPORT:
 141                 return copy_to_user(argp, &at91_wdt_info,
 142                                 sizeof(at91_wdt_info)) ? -EFAULT : 0;
 143         case WDIOC_GETSTATUS:
 144         case WDIOC_GETBOOTSTATUS:
 145                 return put_user(0, p);
 146         case WDIOC_SETOPTIONS:
 147                 if (get_user(new_value, p))
 148                         return -EFAULT;
 149                 if (new_value & WDIOS_DISABLECARD)
 150                         at91_wdt_stop();
 151                 if (new_value & WDIOS_ENABLECARD)
 152                         at91_wdt_start();
 153                 return 0;
 154         case WDIOC_KEEPALIVE:
 155                 at91_wdt_reload();      /* pat the watchdog */
 156                 return 0;
 157         case WDIOC_SETTIMEOUT:
 158                 if (get_user(new_value, p))
 159                         return -EFAULT;
 160                 if (at91_wdt_settimeout(new_value))
 161                         return -EINVAL;
 162                 /* Enable new time value */
 163                 at91_wdt_start();
 164                 /* Return current value */
 165                 return put_user(wdt_time, p);
 166         case WDIOC_GETTIMEOUT:
 167                 return put_user(wdt_time, p);
 168         default:
 169                 return -ENOTTY;
 170         }
 171 }
 172
 173 /*
 174  * Pat the watchdog whenever device is written to.
 175  */
 176 static ssize_t at91_wdt_write(struct file *file, const char *data,
 177                                                 size_t len, loff_t *ppos)
 178 {
 179         at91_wdt_reload();              /* pat the watchdog */
 180         return len;
 181 }
 182
 183 /* ......................................................................... */
 184
 185 static const struct file_operations at91wdt_fops = {
 186         .owner          = THIS_MODULE,
 187         .llseek         = no_llseek,
 188         .unlocked_ioctl = at91_wdt_ioctl,
 189         .open           = at91_wdt_open,
 190         .release        = at91_wdt_close,
 191         .write          = at91_wdt_write,
 192 };
 193
 194 static struct miscdevice at91wdt_miscdev = {
 195         .minor          = WATCHDOG_MINOR,
 196         .name           = "watchdog",
 197         .fops           = &at91wdt_fops,
 198 };
 199
 200 static int __init at91wdt_probe(struct platform_device *pdev)
 201 {
 202         int res;
 203
 204         if (at91wdt_miscdev.parent)
 205                 return -EBUSY;
 206         at91wdt_miscdev.parent = &pdev->dev;
 207
 208         res = misc_register(&at91wdt_miscdev);
 209         if (res)
 210                 return res;
 211
 212         printk(KERN_INFO "AT91 Watchdog Timer enabled (%d seconds%s)\n",
 213                                 wdt_time, nowayout ? ", nowayout" : "");
 214         return 0;
 215 }
 216
 217 static int __exit at91wdt_remove(struct platform_device *pdev)
 218 {
 219         int res;
 220
 221         res = misc_deregister(&at91wdt_miscdev);
 222         if (!res)
 223                 at91wdt_miscdev.parent = NULL;
 224
 225         return res;
 226 }
 227
 228 static void at91wdt_shutdown(struct platform_device *pdev)
 229 {
 230         at91_wdt_stop();
 231 }
 232
 233 #ifdef CONFIG_PM
 234
 235 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
 236 {
 237         at91_wdt_stop();
 238         return 0;
 239 }
 240
 241 static int at91wdt_resume(struct platform_device *pdev)
 242 {
 243         if (at91wdt_busy)
 244                 at91_wdt_start();
 245         return 0;
 246 }
 247
 248 #else
 249 #define at91wdt_suspend NULL
 250 #define at91wdt_resume  NULL
 251 #endif
 252
 253 static struct platform_driver at91wdt_driver = {
 254         .probe          = at91wdt_probe,
 255         .remove         = __exit_p(at91wdt_remove),
 256         .shutdown       = at91wdt_shutdown,
 257         .suspend        = at91wdt_suspend,
 258         .resume         = at91wdt_resume,
 259         .driver         = {
 260                 .name   = "at91_wdt",
 261                 .owner  = THIS_MODULE,
 262         },
 263 };
 264
 265 static int __init at91_wdt_init(void)
 266 {
 267         /* Check that the heartbeat value is within range;
 268            if not reset to the default */
 269         if (at91_wdt_settimeout(wdt_time)) {
 270                 at91_wdt_settimeout(WDT_DEFAULT_TIME);
 271                 pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time);
 272         }
 273
 274         return platform_driver_register(&at91wdt_driver);
 275 }
 276
 277 static void __exit at91_wdt_exit(void)
 278 {
 279         platform_driver_unregister(&at91wdt_driver);
 280 }
 281
 282 module_init(at91_wdt_init);
 283 module_exit(at91_wdt_exit);
 284
 285 MODULE_AUTHOR("Andrew Victor");
 286 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
 287 MODULE_LICENSE("GPL");
 288 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 289 MODULE_ALIAS("platform:at91_wdt");