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         /* See if we got the magic character 'V' and reload the timer */
 154         if(count) {
 155                 if (!nowayout) {
 156                         size_t ofs;
 157
 158                         /* note: just in case someone wrote the magic character
 159                          * five months ago... */
 160                         wdt_expect_close = 0;
 161
 162                         /* now scan */
 163                         for (ofs = 0; ofs != count; ofs++) {
 164                                 char c;
 165                                 if (get_user(c, buf+ofs))
 166                                         return -EFAULT;
 167                                 if (c == 'V')
 168                                         wdt_expect_close = 42;
 169                         }
 170                 }
 171                 /* someone wrote to us, we should restart timer */
 172                 wdt_keepalive();
 173         }
 174         return count;
 175 }
 176
 177 static int fop_open(struct inode * inode, struct file * file)
 178 {
 179         /* Just in case we're already talking to someone... */
 180         if(test_and_set_bit(0, &wdt_is_open))
 181                 return -EBUSY;
 182         /* Good, fire up the show */
 183         wdt_startup();
 184         return nonseekable_open(inode, file);
 185 }
 186
 187 static int fop_close(struct inode * inode, struct file * file)
 188 {
 189         if(wdt_expect_close == 42)
 190                 wdt_turnoff();
 191         else {
 192                 /* wim: shouldn't there be a: del_timer(&timer); */
 193                 printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
 194         }
 195         clear_bit(0, &wdt_is_open);
 196         wdt_expect_close = 0;
 197         return 0;
 198 }
 199
 200 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
 201 {
 202         void __user *argp = (void __user *)arg;
 203         int __user *p = argp;
 204         static struct watchdog_info ident =
 205         {
 206                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 207                 .firmware_version = 1,
 208                 .identity = "ALiM7101",
 209         };
 210
 211         switch(cmd)
 212         {
 213                 case WDIOC_GETSUPPORT:
 214                         return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
 215                 case WDIOC_GETSTATUS:
 216                 case WDIOC_GETBOOTSTATUS:
 217                         return put_user(0, p);
 218                 case WDIOC_KEEPALIVE:
 219                         wdt_keepalive();
 220                         return 0;
 221                 case WDIOC_SETOPTIONS:
 222                 {
 223                         int new_options, retval = -EINVAL;
 224
 225                         if(get_user(new_options, p))
 226                                 return -EFAULT;
 227
 228                         if(new_options & WDIOS_DISABLECARD) {
 229                                 wdt_turnoff();
 230                                 retval = 0;
 231                         }
 232
 233                         if(new_options & WDIOS_ENABLECARD) {
 234                                 wdt_startup();
 235                                 retval = 0;
 236                         }
 237
 238                         return retval;
 239                 }
 240                 case WDIOC_SETTIMEOUT:
 241                 {
 242                         int new_timeout;
 243
 244                         if(get_user(new_timeout, p))
 245                                 return -EFAULT;
 246
 247                         if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
 248                                 return -EINVAL;
 249
 250                         timeout = new_timeout;
 251                         wdt_keepalive();
 252                         /* Fall through */
 253                 }
 254                 case WDIOC_GETTIMEOUT:
 255                         return put_user(timeout, p);
 256                 default:
 257                         return -ENOIOCTLCMD;
 258         }
 259 }
 260
 261 static struct file_operations wdt_fops = {
 262         .owner=         THIS_MODULE,
 263         .llseek=        no_llseek,
 264         .write=         fop_write,
 265         .open=          fop_open,
 266         .release=       fop_close,
 267         .ioctl=         fop_ioctl,
 268 };
 269
 270 static struct miscdevice wdt_miscdev = {
 271         .minor=WATCHDOG_MINOR,
 272         .name="watchdog",
 273         .fops=&wdt_fops,
 274 };
 275
 276 /*
 277  *      Notifier for system down
 278  */
 279
 280 static int wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused)
 281 {
 282         if (code==SYS_DOWN || code==SYS_HALT)
 283                 wdt_turnoff();
 284
 285         if (code==SYS_RESTART) {
 286                 /*
 287                  * Cobalt devices have no way of rebooting themselves other than
 288                  * getting the watchdog to pull reset, so we restart the watchdog on
 289                  * reboot with no heartbeat
 290                  */
 291                 wdt_change(WDT_ENABLE);
 292                 printk(KERN_INFO PFX "Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second.\n");
 293         }
 294         return NOTIFY_DONE;
 295 }
 296
 297 /*
 298  *      The WDT needs to learn about soft shutdowns in order to
 299  *      turn the timebomb registers off.
 300  */
 301
 302 static struct notifier_block wdt_notifier=
 303 {
 304         .notifier_call = wdt_notify_sys,
 305 };
 306
 307 static void __exit alim7101_wdt_unload(void)
 308 {
 309         wdt_turnoff();
 310         /* Deregister */
 311         misc_deregister(&wdt_miscdev);
 312         unregister_reboot_notifier(&wdt_notifier);
 313 }
 314
 315 static int __init alim7101_wdt_init(void)
 316 {
 317         int rc = -EBUSY;
 318         struct pci_dev *ali1543_south;
 319         char tmp;
 320
 321         printk(KERN_INFO PFX "Steve Hill <steve@navaho.co.uk>.\n");
 322         alim7101_pmu = pci_find_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,NULL);
 323         if (!alim7101_pmu) {
 324                 printk(KERN_INFO PFX "ALi M7101 PMU not present - WDT not set\n");
 325                 return -EBUSY;
 326         }
 327
 328         /* Set the WDT in the PMU to 1 second */
 329         pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
 330
 331         ali1543_south = pci_find_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533, NULL);
 332         if (!ali1543_south) {
 333                 printk(KERN_INFO PFX "ALi 1543 South-Bridge not present - WDT not set\n");
 334                 return -EBUSY;
 335         }
 336         pci_read_config_byte(ali1543_south, 0x5e, &tmp);
 337         if ((tmp & 0x1e) != 0x12) {
 338                 printk(KERN_INFO PFX "ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
 339                 return -EBUSY;
 340         }
 341
 342         if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 343         {
 344                 timeout = WATCHDOG_TIMEOUT;
 345                 printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
 346                         timeout);
 347         }
 348
 349         init_timer(&timer);
 350         timer.function = wdt_timer_ping;
 351         timer.data = 1;
 352
 353         rc = misc_register(&wdt_miscdev);
 354         if (rc) {
 355                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 356                         wdt_miscdev.minor, rc);
 357                 goto err_out;
 358         }
 359
 360         rc = register_reboot_notifier(&wdt_notifier);
 361         if (rc) {
 362                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 363                         rc);
 364                 goto err_out_miscdev;
 365         }
 366
 367         printk(KERN_INFO PFX "WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
 368                 timeout, nowayout);
 369         return 0;
 370
 371 err_out_miscdev:
 372         misc_deregister(&wdt_miscdev);
 373 err_out:
 374         return rc;
 375 }
 376
 377 module_init(alim7101_wdt_init);
 378 module_exit(alim7101_wdt_unload);
 379
 380 MODULE_AUTHOR("Steve Hill");
 381 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
 382 MODULE_LICENSE("GPL");
 383 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);