drivers/char/watchdog/alim1535_wdt.c

   1 /*
   2  *      Watchdog for the 7101 PMU version found in the ALi M1535 chipsets
   3  *
   4  *      This program is free software; you can redistribute it and/or
   5  *      modify it under the terms of the GNU General Public License
   6  *      as published by the Free Software Foundation; either version
   7  *      2 of the License, or (at your option) any later version.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/types.h>
  13 #include <linux/miscdevice.h>
  14 #include <linux/watchdog.h>
  15 #include <linux/ioport.h>
  16 #include <linux/notifier.h>
  17 #include <linux/reboot.h>
  18 #include <linux/init.h>
  19 #include <linux/fs.h>
  20 #include <linux/pci.h>
  21
  22 #include <asm/uaccess.h>
  23 #include <asm/io.h>
  24
  25 #define WATCHDOG_NAME "ALi_M1535"
  26 #define PFX WATCHDOG_NAME ": "
  27 #define WATCHDOG_TIMEOUT 60     /* 60 sec default timeout */
  28
  29 /* internal variables */
  30 static unsigned long ali_is_open;
  31 static char ali_expect_release;
  32 static struct pci_dev *ali_pci;
  33 static u32 ali_timeout_bits;    /* stores the computed timeout */
  34 static spinlock_t ali_lock;     /* Guards the hardware */
  35
  36 /* module parameters */
  37 static int timeout = WATCHDOG_TIMEOUT;
  38 module_param(timeout, int, 0);
  39 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (0<timeout<18000, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  40
  41 static int nowayout = WATCHDOG_NOWAYOUT;
  42 module_param(nowayout, int, 0);
  43 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  44
  45 /*
  46  *      ali_start       -       start watchdog countdown
  47  *
  48  *      Starts the timer running providing the timer has a counter
  49  *      configuration set.
  50  */
  51
  52 static void ali_start(void)
  53 {
  54         u32 val;
  55
  56         spin_lock(&ali_lock);
  57
  58         pci_read_config_dword(ali_pci, 0xCC, &val);
  59         val &= ~0x3F;   /* Mask count */
  60         val |= (1<<25) | ali_timeout_bits;
  61         pci_write_config_dword(ali_pci, 0xCC, val);
  62
  63         spin_unlock(&ali_lock);
  64 }
  65
  66 /*
  67  *      ali_stop        -       stop the timer countdown
  68  *
  69  *      Stop the ALi watchdog countdown
  70  */
  71
  72 static void ali_stop(void)
  73 {
  74         u32 val;
  75
  76         spin_lock(&ali_lock);
  77
  78         pci_read_config_dword(ali_pci, 0xCC, &val);
  79         val &= ~0x3F;   /* Mask count to zero (disabled) */
  80         val &= ~(1<<25);/* and for safety mask the reset enable */
  81         pci_write_config_dword(ali_pci, 0xCC, val);
  82
  83         spin_unlock(&ali_lock);
  84 }
  85
  86 /*
  87  *      ali_keepalive   -       send a keepalive to the watchdog
  88  *
  89  *      Send a keepalive to the timer (actually we restart the timer).
  90  */
  91
  92 static void ali_keepalive(void)
  93 {
  94         ali_start();
  95 }
  96
  97 /*
  98  *      ali_settimer    -       compute the timer reload value
  99  *      @t: time in seconds
 100  *
 101  *      Computes the timeout values needed
 102  */
 103
 104 static int ali_settimer(int t)
 105 {
 106         if(t < 0)
 107                 return -EINVAL;
 108         else if(t < 60)
 109                 ali_timeout_bits = t|(1<<6);
 110         else if(t < 3600)
 111                 ali_timeout_bits = (t/60)|(1<<7);
 112         else if(t < 18000)
 113                 ali_timeout_bits = (t/300)|(1<<6)|(1<<7);
 114         else return -EINVAL;
 115
 116         timeout = t;
 117         return 0;
 118 }
 119
 120 /*
 121  *      /dev/watchdog handling
 122  */
 123
 124 /*
 125  *      ali_write       -       writes to ALi watchdog
 126  *      @file: file from VFS
 127  *      @data: user address of data
 128  *      @len: length of data
 129  *      @ppos: pointer to the file offset
 130  *
 131  *      Handle a write to the ALi watchdog. Writing to the file pings
 132  *      the watchdog and resets it. Writing the magic 'V' sequence allows
 133  *      the next close to turn off the watchdog.
 134  */
 135
 136 static ssize_t ali_write(struct file *file, const char __user *data,
 137                               size_t len, loff_t * ppos)
 138 {
 139         /* See if we got the magic character 'V' and reload the timer */
 140         if (len) {
 141                 if (!nowayout) {
 142                         size_t i;
 143
 144                         /* note: just in case someone wrote the magic character
 145                          * five months ago... */
 146                         ali_expect_release = 0;
 147
 148                         /* scan to see whether or not we got the magic character */
 149                         for (i = 0; i != len; i++) {
 150                                 char c;
 151                                 if(get_user(c, data+i))
 152                                         return -EFAULT;
 153                                 if (c == 'V')
 154                                         ali_expect_release = 42;
 155                         }
 156                 }
 157
 158                 /* someone wrote to us, we should reload the timer */
 159                 ali_start();
 160         }
 161         return len;
 162 }
 163
 164 /*
 165  *      ali_ioctl       -       handle watchdog ioctls
 166  *      @inode: VFS inode
 167  *      @file: VFS file pointer
 168  *      @cmd: ioctl number
 169  *      @arg: arguments to the ioctl
 170  *
 171  *      Handle the watchdog ioctls supported by the ALi driver. Really
 172  *      we want an extension to enable irq ack monitoring and the like
 173  */
 174
 175 static int ali_ioctl(struct inode *inode, struct file *file,
 176                           unsigned int cmd, unsigned long arg)
 177 {
 178         void __user *argp = (void __user *)arg;
 179         int __user *p = argp;
 180         static struct watchdog_info ident = {
 181                 .options =              WDIOF_KEEPALIVEPING |
 182                                         WDIOF_SETTIMEOUT |
 183                                         WDIOF_MAGICCLOSE,
 184                 .firmware_version =     0,
 185                 .identity =             "ALi M1535 WatchDog Timer",
 186         };
 187
 188         switch (cmd) {
 189                 case WDIOC_GETSUPPORT:
 190                         return copy_to_user(argp, &ident,
 191                                 sizeof (ident)) ? -EFAULT : 0;
 192
 193                 case WDIOC_GETSTATUS:
 194                 case WDIOC_GETBOOTSTATUS:
 195                         return put_user(0, p);
 196
 197                 case WDIOC_KEEPALIVE:
 198                         ali_keepalive();
 199                         return 0;
 200
 201                 case WDIOC_SETOPTIONS:
 202                 {
 203                         int new_options, retval = -EINVAL;
 204
 205                         if (get_user (new_options, p))
 206                                 return -EFAULT;
 207
 208                         if (new_options & WDIOS_DISABLECARD) {
 209                                 ali_stop();
 210                                 retval = 0;
 211                         }
 212
 213                         if (new_options & WDIOS_ENABLECARD) {
 214                                 ali_start();
 215                                 retval = 0;
 216                         }
 217
 218                         return retval;
 219                 }
 220
 221                 case WDIOC_SETTIMEOUT:
 222                 {
 223                         int new_timeout;
 224
 225                         if (get_user(new_timeout, p))
 226                                 return -EFAULT;
 227
 228                         if (ali_settimer(new_timeout))
 229                             return -EINVAL;
 230
 231                         ali_keepalive();
 232                         /* Fall */
 233                 }
 234
 235                 case WDIOC_GETTIMEOUT:
 236                         return put_user(timeout, p);
 237
 238                 default:
 239                         return -ENOTTY;
 240         }
 241 }
 242
 243 /*
 244  *      ali_open        -       handle open of ali watchdog
 245  *      @inode: inode from VFS
 246  *      @file: file from VFS
 247  *
 248  *      Open the ALi watchdog device. Ensure only one person opens it
 249  *      at a time. Also start the watchdog running.
 250  */
 251
 252 static int ali_open(struct inode *inode, struct file *file)
 253 {
 254         /* /dev/watchdog can only be opened once */
 255         if (test_and_set_bit(0, &ali_is_open))
 256                 return -EBUSY;
 257
 258         /* Activate */
 259         ali_start();
 260         return nonseekable_open(inode, file);
 261 }
 262
 263 /*
 264  *      ali_release     -       close an ALi watchdog
 265  *      @inode: inode from VFS
 266  *      @file: file from VFS
 267  *
 268  *      Close the ALi watchdog device. Actual shutdown of the timer
 269  *      only occurs if the magic sequence has been set.
 270  */
 271
 272 static int ali_release(struct inode *inode, struct file *file)
 273 {
 274         /*
 275          *      Shut off the timer.
 276          */
 277         if (ali_expect_release == 42) {
 278                 ali_stop();
 279         } else {
 280                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 281                 ali_keepalive();
 282         }
 283         clear_bit(0, &ali_is_open);
 284         ali_expect_release = 0;
 285         return 0;
 286 }
 287
 288 /*
 289  *      ali_notify_sys  -       System down notifier
 290  *
 291  *      Notifier for system down
 292  */
 293
 294
 295 static int ali_notify_sys(struct notifier_block *this, unsigned long code, void *unused)
 296 {
 297         if (code==SYS_DOWN || code==SYS_HALT) {
 298                 /* Turn the WDT off */
 299                 ali_stop();
 300         }
 301
 302         return NOTIFY_DONE;
 303 }
 304
 305 /*
 306  *      Data for PCI driver interface
 307  *
 308  *      This data only exists for exporting the supported
 309  *      PCI ids via MODULE_DEVICE_TABLE.  We do not actually
 310  *      register a pci_driver, because someone else might one day
 311  *      want to register another driver on the same PCI id.
 312  */
 313
 314 static struct pci_device_id ali_pci_tbl[] = {
 315         { PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,},
 316         { 0, },
 317 };
 318 MODULE_DEVICE_TABLE(pci, ali_pci_tbl);
 319
 320 /*
 321  *      ali_find_watchdog       -       find a 1535 and 7101
 322  *
 323  *      Scans the PCI hardware for a 1535 series bridge and matching 7101
 324  *      watchdog device. This may be overtight but it is better to be safe
 325  */
 326
 327 static int __init ali_find_watchdog(void)
 328 {
 329         struct pci_dev *pdev;
 330         u32 wdog;
 331
 332         /* Check for a 1535 series bridge */
 333         pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL);
 334         if(pdev == NULL)
 335                 return -ENODEV;
 336         pci_dev_put(pdev);
 337
 338         /* Check for the a 7101 PMU */
 339         pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL);
 340         if(pdev == NULL)
 341                 return -ENODEV;
 342
 343         if(pci_enable_device(pdev)) {
 344                 pci_dev_put(pdev);
 345                 return -EIO;
 346         }
 347
 348         ali_pci = pdev;
 349
 350         /*
 351          *      Initialize the timer bits
 352          */
 353         pci_read_config_dword(pdev, 0xCC, &wdog);
 354
 355         wdog &= ~0x3F;          /* Timer bits */
 356         wdog &= ~((1<<27)|(1<<26)|(1<<25)|(1<<24));     /* Issued events */
 357         wdog &= ~((1<<16)|(1<<13)|(1<<12)|(1<<11)|(1<<10)|(1<<9));      /* No monitor bits */
 358
 359         pci_write_config_dword(pdev, 0xCC, wdog);
 360
 361         return 0;
 362 }
 363
 364 /*
 365  *      Kernel Interfaces
 366  */
 367
 368 static const struct file_operations ali_fops = {
 369         .owner =        THIS_MODULE,
 370         .llseek =       no_llseek,
 371         .write =        ali_write,
 372         .ioctl =        ali_ioctl,
 373         .open =         ali_open,
 374         .release =      ali_release,
 375 };
 376
 377 static struct miscdevice ali_miscdev = {
 378         .minor =        WATCHDOG_MINOR,
 379         .name =         "watchdog",
 380         .fops =         &ali_fops,
 381 };
 382
 383 static struct notifier_block ali_notifier = {
 384         .notifier_call =        ali_notify_sys,
 385 };
 386
 387 /*
 388  *      watchdog_init   -       module initialiser
 389  *
 390  *      Scan for a suitable watchdog and if so initialize it. Return an error
 391  *      if we cannot, the error causes the module to unload
 392  */
 393
 394 static int __init watchdog_init(void)
 395 {
 396         int ret;
 397
 398         spin_lock_init(&ali_lock);
 399
 400         /* Check whether or not the hardware watchdog is there */
 401         if (ali_find_watchdog() != 0) {
 402                 return -ENODEV;
 403         }
 404
 405         /* Check that the timeout value is within it's range ; if not reset to the default */
 406         if (timeout < 1 || timeout >= 18000) {
 407                 timeout = WATCHDOG_TIMEOUT;
 408                 printk(KERN_INFO PFX "timeout value must be 0<timeout<18000, using %d\n",
 409                         timeout);
 410         }
 411
 412         /* Calculate the watchdog's timeout */
 413         ali_settimer(timeout);
 414
 415         ret = misc_register(&ali_miscdev);
 416         if (ret != 0) {
 417                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 418                         WATCHDOG_MINOR, ret);
 419                 goto out;
 420         }
 421
 422         ret = register_reboot_notifier(&ali_notifier);
 423         if (ret != 0) {
 424                 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 425                         ret);
 426                 goto unreg_miscdev;
 427         }
 428
 429         printk(KERN_INFO PFX "initialized. timeout=%d sec (nowayout=%d)\n",
 430                 timeout, nowayout);
 431
 432 out:
 433         return ret;
 434 unreg_miscdev:
 435         misc_deregister(&ali_miscdev);
 436         goto out;
 437 }
 438
 439 /*
 440  *      watchdog_exit   -       module de-initialiser
 441  *
 442  *      Called while unloading a successfully installed watchdog module.
 443  */
 444
 445 static void __exit watchdog_exit(void)
 446 {
 447         /* Stop the timer before we leave */
 448         ali_stop();
 449
 450         /* Deregister */
 451         unregister_reboot_notifier(&ali_notifier);
 452         misc_deregister(&ali_miscdev);
 453         pci_dev_put(ali_pci);
 454 }
 455
 456 module_init(watchdog_init);
 457 module_exit(watchdog_exit);
 458
 459 MODULE_AUTHOR("Alan Cox");
 460 MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
 461 MODULE_LICENSE("GPL");
 462 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);