drivers/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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/types.h>
  15 #include <linux/miscdevice.h>
  16 #include <linux/watchdog.h>
  17 #include <linux/ioport.h>
  18 #include <linux/notifier.h>
  19 #include <linux/reboot.h>
  20 #include <linux/init.h>
  21 #include <linux/fs.h>
  22 #include <linux/pci.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/io.h>
  25
  26 #define WATCHDOG_NAME "ALi_M1535"
  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 DEFINE_SPINLOCK(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,
  40                 "Watchdog timeout in seconds. (0 < timeout < 18000, default="
  41                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  42
  43 static bool nowayout = WATCHDOG_NOWAYOUT;
  44 module_param(nowayout, bool, 0);
  45 MODULE_PARM_DESC(nowayout,
  46                 "Watchdog cannot be stopped once started (default="
  47                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  48
  49 /*
  50  *      ali_start       -       start watchdog countdown
  51  *
  52  *      Starts the timer running providing the timer has a counter
  53  *      configuration set.
  54  */
  55
  56 static void ali_start(void)
  57 {
  58         u32 val;
  59
  60         spin_lock(&ali_lock);
  61
  62         pci_read_config_dword(ali_pci, 0xCC, &val);
  63         val &= ~0x3F;   /* Mask count */
  64         val |= (1 << 25) | ali_timeout_bits;
  65         pci_write_config_dword(ali_pci, 0xCC, val);
  66
  67         spin_unlock(&ali_lock);
  68 }
  69
  70 /*
  71  *      ali_stop        -       stop the timer countdown
  72  *
  73  *      Stop the ALi watchdog countdown
  74  */
  75
  76 static void ali_stop(void)
  77 {
  78         u32 val;
  79
  80         spin_lock(&ali_lock);
  81
  82         pci_read_config_dword(ali_pci, 0xCC, &val);
  83         val &= ~0x3F;           /* Mask count to zero (disabled) */
  84         val &= ~(1 << 25);      /* and for safety mask the reset enable */
  85         pci_write_config_dword(ali_pci, 0xCC, val);
  86
  87         spin_unlock(&ali_lock);
  88 }
  89
  90 /*
  91  *      ali_keepalive   -       send a keepalive to the watchdog
  92  *
  93  *      Send a keepalive to the timer (actually we restart the timer).
  94  */
  95
  96 static void ali_keepalive(void)
  97 {
  98         ali_start();
  99 }
 100
 101 /*
 102  *      ali_settimer    -       compute the timer reload value
 103  *      @t: time in seconds
 104  *
 105  *      Computes the timeout values needed
 106  */
 107
 108 static int ali_settimer(int t)
 109 {
 110         if (t < 0)
 111                 return -EINVAL;
 112         else if (t < 60)
 113                 ali_timeout_bits = t|(1 << 6);
 114         else if (t < 3600)
 115                 ali_timeout_bits = (t / 60)|(1 << 7);
 116         else if (t < 18000)
 117                 ali_timeout_bits = (t / 300)|(1 << 6)|(1 << 7);
 118         else
 119                 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
 150                            magic character five months ago... */
 151                         ali_expect_release = 0;
 152
 153                         /* scan to see whether or not we got
 154                            the magic character */
 155                         for (i = 0; i != len; i++) {
 156                                 char c;
 157                                 if (get_user(c, data + i))
 158                                         return -EFAULT;
 159                                 if (c == 'V')
 160                                         ali_expect_release = 42;
 161                         }
 162                 }
 163
 164                 /* someone wrote to us, we should reload the timer */
 165                 ali_start();
 166         }
 167         return len;
 168 }
 169
 170 /*
 171  *      ali_ioctl       -       handle watchdog ioctls
 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 long ali_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 181 {
 182         void __user *argp = (void __user *)arg;
 183         int __user *p = argp;
 184         static const struct watchdog_info ident = {
 185                 .options =              WDIOF_KEEPALIVEPING |
 186                                         WDIOF_SETTIMEOUT |
 187                                         WDIOF_MAGICCLOSE,
 188                 .firmware_version =     0,
 189                 .identity =             "ALi M1535 WatchDog Timer",
 190         };
 191
 192         switch (cmd) {
 193         case WDIOC_GETSUPPORT:
 194                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 195
 196         case WDIOC_GETSTATUS:
 197         case WDIOC_GETBOOTSTATUS:
 198                 return put_user(0, p);
 199         case WDIOC_SETOPTIONS:
 200         {
 201                 int new_options, retval = -EINVAL;
 202
 203                 if (get_user(new_options, p))
 204                         return -EFAULT;
 205                 if (new_options & WDIOS_DISABLECARD) {
 206                         ali_stop();
 207                         retval = 0;
 208                 }
 209                 if (new_options & WDIOS_ENABLECARD) {
 210                         ali_start();
 211                         retval = 0;
 212                 }
 213                 return retval;
 214         }
 215         case WDIOC_KEEPALIVE:
 216                 ali_keepalive();
 217                 return 0;
 218         case WDIOC_SETTIMEOUT:
 219         {
 220                 int new_timeout;
 221                 if (get_user(new_timeout, p))
 222                         return -EFAULT;
 223                 if (ali_settimer(new_timeout))
 224                         return -EINVAL;
 225                 ali_keepalive();
 226         }
 227                 /* fall through */
 228         case WDIOC_GETTIMEOUT:
 229                 return put_user(timeout, p);
 230         default:
 231                 return -ENOTTY;
 232         }
 233 }
 234
 235 /*
 236  *      ali_open        -       handle open of ali watchdog
 237  *      @inode: inode from VFS
 238  *      @file: file from VFS
 239  *
 240  *      Open the ALi watchdog device. Ensure only one person opens it
 241  *      at a time. Also start the watchdog running.
 242  */
 243
 244 static int ali_open(struct inode *inode, struct file *file)
 245 {
 246         /* /dev/watchdog can only be opened once */
 247         if (test_and_set_bit(0, &ali_is_open))
 248                 return -EBUSY;
 249
 250         /* Activate */
 251         ali_start();
 252         return nonseekable_open(inode, file);
 253 }
 254
 255 /*
 256  *      ali_release     -       close an ALi watchdog
 257  *      @inode: inode from VFS
 258  *      @file: file from VFS
 259  *
 260  *      Close the ALi watchdog device. Actual shutdown of the timer
 261  *      only occurs if the magic sequence has been set.
 262  */
 263
 264 static int ali_release(struct inode *inode, struct file *file)
 265 {
 266         /*
 267          *      Shut off the timer.
 268          */
 269         if (ali_expect_release == 42)
 270                 ali_stop();
 271         else {
 272                 pr_crit("Unexpected close, not stopping watchdog!\n");
 273                 ali_keepalive();
 274         }
 275         clear_bit(0, &ali_is_open);
 276         ali_expect_release = 0;
 277         return 0;
 278 }
 279
 280 /*
 281  *      ali_notify_sys  -       System down notifier
 282  *
 283  *      Notifier for system down
 284  */
 285
 286
 287 static int ali_notify_sys(struct notifier_block *this,
 288                                         unsigned long code, void *unused)
 289 {
 290         if (code == SYS_DOWN || code == SYS_HALT)
 291                 ali_stop();             /* Turn the WDT off */
 292         return NOTIFY_DONE;
 293 }
 294
 295 /*
 296  *      Data for PCI driver interface
 297  *
 298  *      This data only exists for exporting the supported
 299  *      PCI ids via MODULE_DEVICE_TABLE.  We do not actually
 300  *      register a pci_driver, because someone else might one day
 301  *      want to register another driver on the same PCI id.
 302  */
 303
 304 static const struct pci_device_id ali_pci_tbl[] __used = {
 305         { PCI_VENDOR_ID_AL, 0x1533, PCI_ANY_ID, PCI_ANY_ID,},
 306         { PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,},
 307         { 0, },
 308 };
 309 MODULE_DEVICE_TABLE(pci, ali_pci_tbl);
 310
 311 /*
 312  *      ali_find_watchdog       -       find a 1535 and 7101
 313  *
 314  *      Scans the PCI hardware for a 1535 series bridge and matching 7101
 315  *      watchdog device. This may be overtight but it is better to be safe
 316  */
 317
 318 static int __init ali_find_watchdog(void)
 319 {
 320         struct pci_dev *pdev;
 321         u32 wdog;
 322
 323         /* Check for a 1533/1535 series bridge */
 324         pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL);
 325         if (pdev == NULL)
 326                 pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1533, NULL);
 327         if (pdev == NULL)
 328                 return -ENODEV;
 329         pci_dev_put(pdev);
 330
 331         /* Check for the a 7101 PMU */
 332         pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL);
 333         if (pdev == NULL)
 334                 return -ENODEV;
 335
 336         if (pci_enable_device(pdev)) {
 337                 pci_dev_put(pdev);
 338                 return -EIO;
 339         }
 340
 341         ali_pci = pdev;
 342
 343         /*
 344          *      Initialize the timer bits
 345          */
 346         pci_read_config_dword(pdev, 0xCC, &wdog);
 347
 348         /* Timer bits */
 349         wdog &= ~0x3F;
 350         /* Issued events */
 351         wdog &= ~((1 << 27)|(1 << 26)|(1 << 25)|(1 << 24));
 352         /* No monitor bits */
 353         wdog &= ~((1 << 16)|(1 << 13)|(1 << 12)|(1 << 11)|(1 << 10)|(1 << 9));
 354
 355         pci_write_config_dword(pdev, 0xCC, wdog);
 356
 357         return 0;
 358 }
 359
 360 /*
 361  *      Kernel Interfaces
 362  */
 363
 364 static const struct file_operations ali_fops = {
 365         .owner          =       THIS_MODULE,
 366         .llseek         =       no_llseek,
 367         .write          =       ali_write,
 368         .unlocked_ioctl =       ali_ioctl,
 369         .open           =       ali_open,
 370         .release        =       ali_release,
 371 };
 372
 373 static struct miscdevice ali_miscdev = {
 374         .minor =        WATCHDOG_MINOR,
 375         .name =         "watchdog",
 376         .fops =         &ali_fops,
 377 };
 378
 379 static struct notifier_block ali_notifier = {
 380         .notifier_call =        ali_notify_sys,
 381 };
 382
 383 /*
 384  *      watchdog_init   -       module initialiser
 385  *
 386  *      Scan for a suitable watchdog and if so initialize it. Return an error
 387  *      if we cannot, the error causes the module to unload
 388  */
 389
 390 static int __init watchdog_init(void)
 391 {
 392         int ret;
 393
 394         /* Check whether or not the hardware watchdog is there */
 395         if (ali_find_watchdog() != 0)
 396                 return -ENODEV;
 397
 398         /* Check that the timeout value is within it's range;
 399            if not reset to the default */
 400         if (timeout < 1 || timeout >= 18000) {
 401                 timeout = WATCHDOG_TIMEOUT;
 402                 pr_info("timeout value must be 0 < timeout < 18000, using %d\n",
 403                         timeout);
 404         }
 405
 406         /* Calculate the watchdog's timeout */
 407         ali_settimer(timeout);
 408
 409         ret = register_reboot_notifier(&ali_notifier);
 410         if (ret != 0) {
 411                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 412                 goto out;
 413         }
 414
 415         ret = misc_register(&ali_miscdev);
 416         if (ret != 0) {
 417                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 418                        WATCHDOG_MINOR, ret);
 419                 goto unreg_reboot;
 420         }
 421
 422         pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
 423                 timeout, nowayout);
 424
 425 out:
 426         return ret;
 427 unreg_reboot:
 428         unregister_reboot_notifier(&ali_notifier);
 429         goto out;
 430 }
 431
 432 /*
 433  *      watchdog_exit   -       module de-initialiser
 434  *
 435  *      Called while unloading a successfully installed watchdog module.
 436  */
 437
 438 static void __exit watchdog_exit(void)
 439 {
 440         /* Stop the timer before we leave */
 441         ali_stop();
 442
 443         /* Deregister */
 444         misc_deregister(&ali_miscdev);
 445         unregister_reboot_notifier(&ali_notifier);
 446         pci_dev_put(ali_pci);
 447 }
 448
 449 module_init(watchdog_init);
 450 module_exit(watchdog_exit);
 451
 452 MODULE_AUTHOR("Alan Cox");
 453 MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
 454 MODULE_LICENSE("GPL");