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/kernel.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/types.h>
  22 #include <linux/watchdog.h>
  23 #include <linux/uaccess.h>
  24 #include <mach/at91_st.h>
  25
  26 #define WDT_DEFAULT_TIME        5       /* seconds */
  27 #define WDT_MAX_TIME            256     /* seconds */
  28
  29 static int wdt_time = WDT_DEFAULT_TIME;
  30 static int nowayout = WATCHDOG_NOWAYOUT;
  31
  32 module_param(wdt_time, int, 0);
  33 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  34                                 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  35
  36 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  37 module_param(nowayout, int, 0);
  38 MODULE_PARM_DESC(nowayout,
  39                 "Watchdog cannot be stopped once started (default="
  40                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  41 #endif
  42
  43
  44 static unsigned long at91wdt_busy;
  45
  46 /* ......................................................................... */
  47
  48 /*
  49  * Disable the watchdog.
  50  */
  51 static inline void at91_wdt_stop(void)
  52 {
  53         at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
  54 }
  55
  56 /*
  57  * Enable and reset the watchdog.
  58  */
  59 static inline void at91_wdt_start(void)
  60 {
  61         at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  62                                 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
  63         at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
  64 }
  65
  66 /*
  67  * Reload the watchdog timer.  (ie, pat the watchdog)
  68  */
  69 static inline void at91_wdt_reload(void)
  70 {
  71         at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
  72 }
  73
  74 /* ......................................................................... */
  75
  76 /*
  77  * Watchdog device is opened, and watchdog starts running.
  78  */
  79 static int at91_wdt_open(struct inode *inode, struct file *file)
  80 {
  81         if (test_and_set_bit(0, &at91wdt_busy))
  82                 return -EBUSY;
  83
  84         at91_wdt_start();
  85         return nonseekable_open(inode, file);
  86 }
  87
  88 /*
  89  * Close the watchdog device.
  90  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
  91  *  disabled.
  92  */
  93 static int at91_wdt_close(struct inode *inode, struct file *file)
  94 {
  95         /* Disable the watchdog when file is closed */
  96         if (!nowayout)
  97                 at91_wdt_stop();
  98
  99         clear_bit(0, &at91wdt_busy);
 100         return 0;
 101 }
 102
 103 /*
 104  * Change the watchdog time interval.
 105  */
 106 static int at91_wdt_settimeout(int new_time)
 107 {
 108         /*
 109          * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
 110          *
 111          * Since WDV is a 16-bit counter, the maximum period is
 112          * 65536 / 0.256 = 256 seconds.
 113          */
 114         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 115                 return -EINVAL;
 116
 117         /* Set new watchdog time. It will be used when
 118            at91_wdt_start() is called. */
 119         wdt_time = new_time;
 120         return 0;
 121 }
 122
 123 static struct watchdog_info at91_wdt_info = {
 124         .identity       = "at91 watchdog",
 125         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 126 };
 127
 128 /*
 129  * Handle commands from user-space.
 130  */
 131 static long at91_wdt_ioctl(struct file *file,
 132                                         unsigned int cmd, unsigned long arg)
 133 {
 134         void __user *argp = (void __user *)arg;
 135         int __user *p = argp;
 136         int new_value;
 137
 138         switch (cmd) {
 139         case WDIOC_GETSUPPORT:
 140                 return copy_to_user(argp, &at91_wdt_info,
 141                                 sizeof(at91_wdt_info)) ? -EFAULT : 0;
 142         case WDIOC_GETSTATUS:
 143         case WDIOC_GETBOOTSTATUS:
 144                 return put_user(0, p);
 145         case WDIOC_SETOPTIONS:
 146                 if (get_user(new_value, p))
 147                         return -EFAULT;
 148                 if (new_value & WDIOS_DISABLECARD)
 149                         at91_wdt_stop();
 150                 if (new_value & WDIOS_ENABLECARD)
 151                         at91_wdt_start();
 152                 return 0;
 153         case WDIOC_KEEPALIVE:
 154                 at91_wdt_reload();      /* pat the watchdog */
 155                 return 0;
 156         case WDIOC_SETTIMEOUT:
 157                 if (get_user(new_value, p))
 158                         return -EFAULT;
 159                 if (at91_wdt_settimeout(new_value))
 160                         return -EINVAL;
 161                 /* Enable new time value */
 162                 at91_wdt_start();
 163                 /* Return current value */
 164                 return put_user(wdt_time, p);
 165         case WDIOC_GETTIMEOUT:
 166                 return put_user(wdt_time, p);
 167         default:
 168                 return -ENOTTY;
 169         }
 170 }
 171
 172 /*
 173  * Pat the watchdog whenever device is written to.
 174  */
 175 static ssize_t at91_wdt_write(struct file *file, const char *data,
 176                                                 size_t len, loff_t *ppos)
 177 {
 178         at91_wdt_reload();              /* pat the watchdog */
 179         return len;
 180 }
 181
 182 /* ......................................................................... */
 183
 184 static const struct file_operations at91wdt_fops = {
 185         .owner          = THIS_MODULE,
 186         .llseek         = no_llseek,
 187         .unlocked_ioctl = at91_wdt_ioctl,
 188         .open           = at91_wdt_open,
 189         .release        = at91_wdt_close,
 190         .write          = at91_wdt_write,
 191 };
 192
 193 static struct miscdevice at91wdt_miscdev = {
 194         .minor          = WATCHDOG_MINOR,
 195         .name           = "watchdog",
 196         .fops           = &at91wdt_fops,
 197 };
 198
 199 static int __init at91wdt_probe(struct platform_device *pdev)
 200 {
 201         int res;
 202
 203         if (at91wdt_miscdev.parent)
 204                 return -EBUSY;
 205         at91wdt_miscdev.parent = &pdev->dev;
 206
 207         res = misc_register(&at91wdt_miscdev);
 208         if (res)
 209                 return res;
 210
 211         printk(KERN_INFO "AT91 Watchdog Timer enabled (%d seconds%s)\n",
 212                                 wdt_time, nowayout ? ", nowayout" : "");
 213         return 0;
 214 }
 215
 216 static int __exit at91wdt_remove(struct platform_device *pdev)
 217 {
 218         int res;
 219
 220         res = misc_deregister(&at91wdt_miscdev);
 221         if (!res)
 222                 at91wdt_miscdev.parent = NULL;
 223
 224         return res;
 225 }
 226
 227 static void at91wdt_shutdown(struct platform_device *pdev)
 228 {
 229         at91_wdt_stop();
 230 }
 231
 232 #ifdef CONFIG_PM
 233
 234 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
 235 {
 236         at91_wdt_stop();
 237         return 0;
 238 }
 239
 240 static int at91wdt_resume(struct platform_device *pdev)
 241 {
 242         if (at91wdt_busy)
 243                 at91_wdt_start();
 244         return 0;
 245 }
 246
 247 #else
 248 #define at91wdt_suspend NULL
 249 #define at91wdt_resume  NULL
 250 #endif
 251
 252 static struct platform_driver at91wdt_driver = {
 253         .probe          = at91wdt_probe,
 254         .remove         = __exit_p(at91wdt_remove),
 255         .shutdown       = at91wdt_shutdown,
 256         .suspend        = at91wdt_suspend,
 257         .resume         = at91wdt_resume,
 258         .driver         = {
 259                 .name   = "at91_wdt",
 260                 .owner  = THIS_MODULE,
 261         },
 262 };
 263
 264 static int __init at91_wdt_init(void)
 265 {
 266         /* Check that the heartbeat value is within range;
 267            if not reset to the default */
 268         if (at91_wdt_settimeout(wdt_time)) {
 269                 at91_wdt_settimeout(WDT_DEFAULT_TIME);
 270                 pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time);
 271         }
 272
 273         return platform_driver_register(&at91wdt_driver);
 274 }
 275
 276 static void __exit at91_wdt_exit(void)
 277 {
 278         platform_driver_unregister(&at91wdt_driver);
 279 }
 280
 281 module_init(at91_wdt_init);
 282 module_exit(at91_wdt_exit);
 283
 284 MODULE_AUTHOR("Andrew Victor");
 285 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
 286 MODULE_LICENSE("GPL");
 287 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 288 MODULE_ALIAS("platform:at91_wdt");