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