drivers/char/watchdog/alim7101_wdt.c

   1 /*
   2  *      ALi M7101 PMU Computer Watchdog Timer driver
   3  *
   4  *      Based on w83877f_wdt.c by Scott Jennings <linuxdrivers@oro.net>
   5  *      and the Cobalt kernel WDT timer driver by Tim Hockin
   6  *                                            <thockin@cobaltnet.com>
   7  *
   8  *      (c)2002 Steve Hill <steve@navaho.co.uk>
   9  *
  10  *  This WDT driver is different from most other Linux WDT
  11  *  drivers in that the driver will ping the watchdog by itself,
  12  *  because this particular WDT has a very short timeout (1.6
  13  *  seconds) and it would be insane to count on any userspace
  14  *  daemon always getting scheduled within that time frame.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/types.h>
  20 #include <linux/timer.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/watchdog.h>
  23 #include <linux/ioport.h>
  24 #include <linux/notifier.h>
  25 #include <linux/reboot.h>
  26 #include <linux/init.h>
  27 #include <linux/fs.h>
  28 #include <linux/pci.h>
  29
  30 #include <asm/io.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/system.h>
  33
  34 #define OUR_NAME "alim7101_wdt"
  35 #define PFX OUR_NAME ": "
  36
  37 #define WDT_ENABLE 0x9C
  38 #define WDT_DISABLE 0x8C
  39
  40 #define ALI_7101_WDT    0x92
  41 #define ALI_WDT_ARM     0x01
  42
  43 /*
  44  * We're going to use a 1 second timeout.
  45  * If we reset the watchdog every ~250ms we should be safe.  */
  46
  47 #define WDT_INTERVAL (HZ/4+1)
  48
  49 /*
  50  * We must not require too good response from the userspace daemon.
  51  * Here we require the userspace daemon to send us a heartbeat
  52  * char to /dev/watchdog every 30 seconds.
  53  */
  54
  55 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
  56 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  57 module_param(timeout, int, 0);
  58 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  59
  60 static void wdt_timer_ping(unsigned long);
  61 static struct timer_list timer;
  62 static unsigned long next_heartbeat;
  63 static unsigned long wdt_is_open;
  64 static char wdt_expect_close;
  65 static struct pci_dev *alim7101_pmu;
  66
  67 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  68 static int nowayout = 1;
  69 #else
  70 static int nowayout = 0;
  71 #endif
  72
  73 module_param(nowayout, int, 0);
  74 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  75
  76 /*
  77  *      Whack the dog
  78  */
  79
  80 static void wdt_timer_ping(unsigned long data)
  81 {
  82         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
  83          * we agree to ping the WDT
  84          */
  85         char    tmp;
  86
  87         if(time_before(jiffies, next_heartbeat))
  88         {
  89                 /* Ping the WDT (this is actually a disarm/arm sequence) */
  90                 pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
  91                 pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
  92                 pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp | ALI_WDT_ARM));
  93         } else {
  94                 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
  95         }
  96         /* Re-set the timer interval */
  97         timer.expires = jiffies + WDT_INTERVAL;
  98         add_timer(&timer);
  99 }
 100
 101 /*
 102  * Utility routines
 103  */
 104
 105 static void wdt_change(int writeval)
 106 {
 107         char    tmp;
 108
 109         pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
 110         if (writeval == WDT_ENABLE)
 111                 pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp | ALI_WDT_ARM));
 112         else
 113                 pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
 114 }
 115
 116 static void wdt_startup(void)
 117 {
 118         next_heartbeat = jiffies + (timeout * HZ);
 119
 120         /* We must enable before we kick off the timer in case the timer
 121            occurs as we ping it */
 122
 123         wdt_change(WDT_ENABLE);
 124
 125         /* Start the timer */
 126         timer.expires = jiffies + WDT_INTERVAL;
 127         add_timer(&timer);
 128
 129
 130         printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 131 }
 132
 133 static void wdt_turnoff(void)
 134 {
 135         /* Stop the timer */
 136         del_timer_sync(&timer);
 137         wdt_change(WDT_DISABLE);
 138         printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 139 }
 140
 141 static void wdt_keepalive(void)
 142 {
 143         /* user land ping */
 144         next_heartbeat = jiffies + (timeout * HZ);
 145 }
 146
 147 /*
 148  * /dev/watchdog handling
 149  */
 150
 151 static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
 152 {
 153         /* We can't seek */
 154         if(ppos != &file->f_pos)
 155                 return -ESPIPE;
 156
 157         /* See if we got the magic character 'V' and reload the timer */
 158         if(count) {
 159                 if (!nowayout) {
 160                         size_t ofs;
 161
 162                         /* note: just in case someone wrote the magic character
 163                          * five months ago... */
 164                         wdt_expect_close = 0;
 165
 166                         /* now scan */
 167                         for (ofs = 0; ofs != count; ofs++) {
 168                                 char c;
 169                                 if (get_user(c, buf+ofs))
 170                                         return -EFAULT;
 171                                 if (c == 'V')
 172                                         wdt_expect_close = 42;
 173                         }
 174                 }
 175                 /* someone wrote to us, we should restart timer */
 176                 wdt_keepalive();
 177         }
 178         return count;
 179 }
 180
 181 static int fop_open(struct inode * inode, struct file * file)
 182 {
 183         /* Just in case we're already talking to someone... */
 184         if(test_and_set_bit(0, &wdt_is_open))
 185                 return -EBUSY;
 186         /* Good, fire up the show */
 187         wdt_startup();
 188         return 0;
 189 }
 190
 191 static int fop_close(struct inode * inode, struct file * file)
 192 {
 193         if(wdt_expect_close == 42)
 194                 wdt_turnoff();
 195         else {
 196                 /* wim: shouldn't there be a: del_timer(&timer); */
 197                 printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
 198         }
 199         clear_bit(0, &wdt_is_open);
 200         wdt_expect_close = 0;
 201         return 0;
 202 }
 203
 204 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
 205 {
 206         void __user *argp = (void __user *)arg;
 207         int __user *p = argp;
 208         static struct watchdog_info ident =
 209         {
 210                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 211                 .firmware_version = 1,
 212                 .identity = "ALiM7101",
 213         };
 214
 215         switch(cmd)
 216         {
 217                 case WDIOC_GETSUPPORT:
 218                         return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
 219                 case WDIOC_GETSTATUS:
 220                 case WDIOC_GETBOOTSTATUS:
 221                         return put_user(0, p);
 222                 case WDIOC_KEEPALIVE:
 223                         wdt_keepalive();
 224                         return 0;
 225                 case WDIOC_SETOPTIONS:
 226                 {
 227                         int new_options, retval = -EINVAL;
 228
 229                         if(get_user(new_options, p))
 230                                 return -EFAULT;
 231
 232                         if(new_options & WDIOS_DISABLECARD) {
 233                                 wdt_turnoff();
 234                                 retval = 0;
 235                         }
 236
 237                         if(new_options & WDIOS_ENABLECARD) {
 238                                 wdt_startup();
 239                                 retval = 0;
 240                         }
 241
 242                         return retval;
 243                 }
 244                 case WDIOC_SETTIMEOUT:
 245                 {
 246                         int new_timeout;
 247
 248                         if(get_user(new_timeout, p))
 249                                 return -EFAULT;
 250
 251                         if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
 252                                 return -EINVAL;
 253
 254                         timeout = new_timeout;
 255                         wdt_keepalive();
 256                         /* Fall through */
 257                 }
 258                 case WDIOC_GETTIMEOUT:
 259                         return put_user(timeout, p);
 260                 default:
 261                         return -ENOIOCTLCMD;
 262         }
 263 }
 264
 265 static struct file_operations wdt_fops = {
 266         .owner=         THIS_MODULE,
 267         .llseek=        no_llseek,
 268         .write=         fop_write,
 269         .open=          fop_open,
 270         .release=       fop_close,
 271         .ioctl=         fop_ioctl,
 272 };
 273
 274 static struct miscdevice wdt_miscdev = {
 275         .minor=WATCHDOG_MINOR,
 276         .name="watchdog",
 277         .fops=&wdt_fops,
 278 };
 279
 280 /*
 281  *      Notifier for system down
 282  */
 283
 284 static int wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused)
 285 {
 286         if (code==SYS_DOWN || code==SYS_HALT)
 287                 wdt_turnoff();
 288
 289         if (code==SYS_RESTART) {
 290                 /*
 291                  * Cobalt devices have no way of rebooting themselves other than
 292                  * getting the watchdog to pull reset, so we restart the watchdog on
 293                  * reboot with no heartbeat
 294                  */
 295                 wdt_change(WDT_ENABLE);
 296                 printk(KERN_INFO PFX "Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second.\n");
 297         }
 298         return NOTIFY_DONE;
 299 }
 300
 301 /*
 302  *      The WDT needs to learn about soft shutdowns in order to
 303  *      turn the timebomb registers off.
 304  */
 305
 306 static struct notifier_block wdt_notifier=
 307 {
 308         .notifier_call = wdt_notify_sys,
 309 };
 310
 311 static void __exit alim7101_wdt_unload(void)
 312 {
 313         wdt_turnoff();
 314         /* Deregister */
 315         misc_deregister(&wdt_miscdev);
 316         unregister_reboot_notifier(&wdt_notifier);
 317 }
 318
 319 static int __init alim7101_wdt_init(void)
 320 {
 321         int rc = -EBUSY;
 322         struct pci_dev *ali1543_south;
 323         char tmp;
 324
 325         printk(KERN_INFO PFX "Steve Hill <steve@navaho.co.uk>.\n");
 326         alim7101_pmu = pci_find_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,NULL);
 327         if (!alim7101_pmu) {
 328                 printk(KERN_INFO PFX "ALi M7101 PMU not present - WDT not set\n");
 329                 return -EBUSY;
 330         }
 331
 332         /* Set the WDT in the PMU to 1 second */
 333         pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
 334
 335         ali1543_south = pci_find_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533, NULL);
 336         if (!ali1543_south) {
 337                 printk(KERN_INFO PFX "ALi 1543 South-Bridge not present - WDT not set\n");
 338                 return -EBUSY;
 339         }
 340         pci_read_config_byte(ali1543_south, 0x5e, &tmp);
 341         if ((tmp & 0x1e) != 0x12) {
 342                 printk(KERN_INFO PFX "ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
 343                 return -EBUSY;
 344         }
 345
 346         if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 347         {
 348                 timeout = WATCHDOG_TIMEOUT;
 349                 printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
 350                         timeout);
 351         }
 352
 353         init_timer(&timer);
 354         timer.function = wdt_timer_ping;
 355         timer.data = 1;
 356
 357         rc = misc_register(&wdt_miscdev);
 358         if (rc) {
 359                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 360                         wdt_miscdev.minor, rc);
 361                 goto err_out;
 362         }
 363
 364         rc = register_reboot_notifier(&wdt_notifier);
 365         if (rc) {
 366                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 367                         rc);
 368                 goto err_out_miscdev;
 369         }
 370
 371         printk(KERN_INFO PFX "WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
 372                 timeout, nowayout);
 373         return 0;
 374
 375 err_out_miscdev:
 376         misc_deregister(&wdt_miscdev);
 377 err_out:
 378         return rc;
 379 }
 380
 381 module_init(alim7101_wdt_init);
 382 module_exit(alim7101_wdt_unload);
 383
 384 MODULE_AUTHOR("Steve Hill");
 385 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
 386 MODULE_LICENSE("GPL");
 387 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);