kernel/linux/drivers/char/watchdog/softdog.c

   1 /*
   2  *      SoftDog 0.07:   A Software Watchdog Device
   3  *
   4  *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
   5  *                              http://www.redhat.com
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  *
  12  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  13  *      warranty for any of this software. This material is provided
  14  *      "AS-IS" and at no charge.
  15  *
  16  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  17  *
  18  *      Software only watchdog driver. Unlike its big brother the WDT501P
  19  *      driver this won't always recover a failed machine.
  20  *
  21  *  03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
  22  *      Modularised.
  23  *      Added soft_margin; use upon insmod to change the timer delay.
  24  *      NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
  25  *          minors.
  26  *
  27  *  19980911 Alan Cox
  28  *      Made SMP safe for 2.3.x
  29  *
  30  *  20011127 Joel Becker (jlbec@evilplan.org>
  31  *      Added soft_noboot; Allows testing the softdog trigger without
  32  *      requiring a recompile.
  33  *      Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
  34  *
  35  *  20020530 Joel Becker <joel.becker@oracle.com>
  36  *      Added Matt Domsch's nowayout module option.
  37  */
  38
  39 #include <linux/module.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/config.h>
  42 #include <linux/types.h>
  43 #include <linux/timer.h>
  44 #include <linux/delay.h>                // added by ccchiu
  45 #include <linux/miscdevice.h>
  46 #include <linux/watchdog.h>
  47 #include <linux/fs.h>
  48 #include <linux/notifier.h>
  49 #include <linux/reboot.h>
  50 #include <linux/init.h>
  51 #include <asm/uaccess.h>
  52
  53
  54 #define PFX "SoftDog: "
  55
  56 //#define TIMER_MARGIN  60              /* Default is 60 seconds */
  57 #define TIMER_MARGIN    2               // modified by ccchiu
  58 static int soft_margin = TIMER_MARGIN;  /* in seconds */
  59 module_param(soft_margin, int, 0);
  60 MODULE_PARM_DESC(soft_margin, "Watchdog soft_margin in seconds. (0<soft_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
  61
  62 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  63 static int nowayout = 1;
  64 #else
  65 static int nowayout = 0;
  66 #endif
  67
  68 module_param(nowayout, int, 0);
  69 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  70
  71 #ifdef ONLY_TESTING
  72 static int soft_noboot = 1;
  73 #else
  74 static int soft_noboot = 0;
  75 #endif  /* ONLY_TESTING */
  76
  77 module_param(soft_noboot, int, 0);
  78 MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
  79
  80 /*
  81  *      Our timer
  82  */
  83
  84 static void watchdog_fire(unsigned long);
  85
  86 static struct timer_list watchdog_ticktock =
  87                 TIMER_INITIALIZER(watchdog_fire, 0, 0);
  88 static unsigned long timer_alive;
  89 static char expect_close;
  90
  91
  92 /*
  93  *      If the timer expires..
  94  */
  95
  96 static void watchdog_fire(unsigned long data)
  97 {
  98 #if 0
  99         if (soft_noboot)
 100                 printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
 101         else
 102         {
 103                 printk(KERN_CRIT PFX "Initiating system reboot.\n");
 104                 machine_restart(NULL);
 105                 printk(KERN_CRIT PFX "Reboot didn't ?????\n");
 106         }
 107 #endif
 108 #if 0
 109         *(volatile int*)0xFFFE0404 |= 0x0020;
 110
 111         *(volatile int*)0xFFFE040C |= 0x0020;
 112         udelay(2000);
 113         *(volatile int*)0xFFFE040C &= ~(0x0020);
 114 #endif
 115 #if 1
 116         int i;
 117
 118         //GPIO->GPIODir |= 0x0020;
 119         *(volatile int*)0xFFFE0404 |= 0x0020;
 120
 121         for(i = 0; i < 5; i ++) {
 122                 //GPIO->GPIOio  &= ~(0x0020);
 123                 *(volatile int*)0xFFFE040C |= 0x0020;
 124                 udelay(50000);
 125                 //GPIO->GPIOio  |= 0x0020;
 126                 *(volatile int*)0xFFFE040C &= ~(0x0020);
 127                 udelay(50000);
 128         }
 129
 130 #endif
 131         //printk("watchdog_fire - softdog timer triggered\n");
 132
 133         mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
 134
 135 }
 136
 137 /*
 138  *      Softdog operations
 139  */
 140
 141 static int softdog_keepalive(void)
 142 {
 143         mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
 144         return 0;
 145 }
 146
 147 static int softdog_stop(void)
 148 {
 149         del_timer(&watchdog_ticktock);
 150         return 0;
 151 }
 152
 153 static int softdog_set_heartbeat(int t)
 154 {
 155         if ((t < 0x0001) || (t > 0xFFFF))
 156                 return -EINVAL;
 157
 158         soft_margin = t;
 159         return 0;
 160 }
 161
 162 /*
 163  *      /dev/watchdog handling
 164  */
 165
 166 static int softdog_open(struct inode *inode, struct file *file)
 167 {
 168         if(test_and_set_bit(0, &timer_alive))
 169                 return -EBUSY;
 170         if (nowayout)
 171                 __module_get(THIS_MODULE);
 172         /*
 173          *      Activate timer
 174          */
 175         softdog_keepalive();
 176         return nonseekable_open(inode, file);
 177 }
 178
 179 static int softdog_release(struct inode *inode, struct file *file)
 180 {
 181         /*
 182          *      Shut off the timer.
 183          *      Lock it in if it's a module and we set nowayout
 184          */
 185         if (expect_close == 42) {
 186                 softdog_stop();
 187         } else {
 188                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 189                 softdog_keepalive();
 190         }
 191         clear_bit(0, &timer_alive);
 192         expect_close = 0;
 193         return 0;
 194 }
 195
 196 static ssize_t softdog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
 197 {
 198         /*
 199          *      Refresh the timer.
 200          */
 201         if(len) {
 202                 if (!nowayout) {
 203                         size_t i;
 204
 205                         /* In case it was set long ago */
 206                         expect_close = 0;
 207
 208                         for (i = 0; i != len; i++) {
 209                                 char c;
 210
 211                                 if (get_user(c, data + i))
 212                                         return -EFAULT;
 213                                 if (c == 'V')
 214                                         expect_close = 42;
 215                         }
 216                 }
 217                 softdog_keepalive();
 218         }
 219         return len;
 220 }
 221
 222 static int softdog_ioctl(struct inode *inode, struct file *file,
 223         unsigned int cmd, unsigned long arg)
 224 {
 225         void __user *argp = (void __user *)arg;
 226         int __user *p = argp;
 227         int new_margin;
 228         static struct watchdog_info ident = {
 229                 .options =              WDIOF_SETTIMEOUT |
 230                                         WDIOF_KEEPALIVEPING |
 231                                         WDIOF_MAGICCLOSE,
 232                 .firmware_version =     0,
 233                 .identity =             "Software Watchdog",
 234         };
 235         switch (cmd) {
 236                 default:
 237                         return -ENOIOCTLCMD;
 238                 case WDIOC_GETSUPPORT:
 239                         return copy_to_user(argp, &ident,
 240                                 sizeof(ident)) ? -EFAULT : 0;
 241                 case WDIOC_GETSTATUS:
 242                 case WDIOC_GETBOOTSTATUS:
 243                         return put_user(0, p);
 244                 case WDIOC_KEEPALIVE:
 245                         softdog_keepalive();
 246                         return 0;
 247                 case WDIOC_SETTIMEOUT:
 248                         if (get_user(new_margin, p))
 249                                 return -EFAULT;
 250                         if (softdog_set_heartbeat(new_margin))
 251                                 return -EINVAL;
 252                         softdog_keepalive();
 253                         /* Fall */
 254                 case WDIOC_GETTIMEOUT:
 255                         return put_user(soft_margin, p);
 256         }
 257 }
 258
 259 /*
 260  *      Notifier for system down
 261  */
 262
 263 static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
 264         void *unused)
 265 {
 266         if(code==SYS_DOWN || code==SYS_HALT) {
 267                 /* Turn the WDT off */
 268                 softdog_stop();
 269         }
 270         return NOTIFY_DONE;
 271 }
 272
 273 /*
 274  *      Kernel Interfaces
 275  */
 276
 277 static struct file_operations softdog_fops = {
 278         .owner          = THIS_MODULE,
 279         .llseek         = no_llseek,
 280         .write          = softdog_write,
 281         .ioctl          = softdog_ioctl,
 282         .open           = softdog_open,
 283         .release        = softdog_release,
 284 };
 285
 286 static struct miscdevice softdog_miscdev = {
 287         .minor          = WATCHDOG_MINOR,
 288         .name           = "watchdog",
 289         .fops           = &softdog_fops,
 290 };
 291
 292 static struct notifier_block softdog_notifier = {
 293         .notifier_call  = softdog_notify_sys,
 294 };
 295
 296 static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
 297
 298 static int __init watchdog_init(void)
 299 {
 300         int ret;
 301
 302 #if 0
 303         /* Check that the soft_margin value is within it's range ; if not reset to the default */
 304         if (softdog_set_heartbeat(soft_margin)) {
 305                 softdog_set_heartbeat(TIMER_MARGIN);
 306                 printk(KERN_INFO PFX "soft_margin value must be 0<soft_margin<65536, using %d\n",
 307                         TIMER_MARGIN);
 308         }
 309
 310         ret = register_reboot_notifier(&softdog_notifier);
 311         if (ret) {
 312                 printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 313                         ret);
 314                 return ret;
 315         }
 316
 317         ret = misc_register(&softdog_miscdev);
 318         if (ret) {
 319                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 320                         WATCHDOG_MINOR, ret);
 321                 unregister_reboot_notifier(&softdog_notifier);
 322                 return ret;
 323         }
 324 #endif(ccchiu)
 325
 326         printk(banner, soft_noboot, soft_margin, nowayout);
 327         // added by ccchiu
 328         watchdog_fire(0);
 329         mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
 330
 331
 332         return 0;
 333 }
 334
 335 static void __exit watchdog_exit(void)
 336 {
 337         misc_deregister(&softdog_miscdev);
 338         unregister_reboot_notifier(&softdog_notifier);
 339 }
 340
 341 module_init(watchdog_init);
 342 module_exit(watchdog_exit);
 343
 344 MODULE_AUTHOR("Alan Cox");
 345 MODULE_DESCRIPTION("Software Watchdog Device Driver");
 346 MODULE_LICENSE("GPL");
 347 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);