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