drivers/watchdog/alim1535_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Watchdog for the 7101 PMU version found in the ALi M1535 chipsets
   4  */
   5
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/module.h>
   9 #include <linux/moduleparam.h>
  10 #include <linux/types.h>
  11 #include <linux/miscdevice.h>
  12 #include <linux/watchdog.h>
  13 #include <linux/ioport.h>
  14 #include <linux/notifier.h>
  15 #include <linux/reboot.h>
  16 #include <linux/init.h>
  17 #include <linux/fs.h>
  18 #include <linux/pci.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/io.h>
  21
  22 #define WATCHDOG_NAME "ALi_M1535"
  23 #define WATCHDOG_TIMEOUT 60     /* 60 sec default timeout */
  24
  25 /* internal variables */
  26 static unsigned long ali_is_open;
  27 static char ali_expect_release;
  28 static struct pci_dev *ali_pci;
  29 static u32 ali_timeout_bits;            /* stores the computed timeout */
  30 static DEFINE_SPINLOCK(ali_lock);       /* Guards the hardware */
  31
  32 /* module parameters */
  33 static int timeout = WATCHDOG_TIMEOUT;
  34 module_param(timeout, int, 0);
  35 MODULE_PARM_DESC(timeout,
  36                 "Watchdog timeout in seconds. (0 < timeout < 18000, default="
  37                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  38
  39 static bool nowayout = WATCHDOG_NOWAYOUT;
  40 module_param(nowayout, bool, 0);
  41 MODULE_PARM_DESC(nowayout,
  42                 "Watchdog cannot be stopped once started (default="
  43                                 __MODULE_STRING(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
 115                 return -EINVAL;
 116
 117         timeout = t;
 118         return 0;
 119 }
 120
 121 /*
 122  *      /dev/watchdog handling
 123  */
 124
 125 /*
 126  *      ali_write       -       writes to ALi watchdog
 127  *      @file: file from VFS
 128  *      @data: user address of data
 129  *      @len: length of data
 130  *      @ppos: pointer to the file offset
 131  *
 132  *      Handle a write to the ALi watchdog. Writing to the file pings
 133  *      the watchdog and resets it. Writing the magic 'V' sequence allows
 134  *      the next close to turn off the watchdog.
 135  */
 136
 137 static ssize_t ali_write(struct file *file, const char __user *data,
 138                                                 size_t len, loff_t *ppos)
 139 {
 140         /* See if we got the magic character 'V' and reload the timer */
 141         if (len) {
 142                 if (!nowayout) {
 143                         size_t i;
 144
 145                         /* note: just in case someone wrote the
 146                            magic character five months ago... */
 147                         ali_expect_release = 0;
 148
 149                         /* scan to see whether or not we got
 150                            the magic character */
 151                         for (i = 0; i != len; i++) {
 152                                 char c;
 153                                 if (get_user(c, data + i))
 154                                         return -EFAULT;
 155                                 if (c == 'V')
 156                                         ali_expect_release = 42;
 157                         }
 158                 }
 159
 160                 /* someone wrote to us, we should reload the timer */
 161                 ali_start();
 162         }
 163         return len;
 164 }
 165
 166 /*
 167  *      ali_ioctl       -       handle watchdog ioctls
 168  *      @file: VFS file pointer
 169  *      @cmd: ioctl number
 170  *      @arg: arguments to the ioctl
 171  *
 172  *      Handle the watchdog ioctls supported by the ALi driver. Really
 173  *      we want an extension to enable irq ack monitoring and the like
 174  */
 175
 176 static long ali_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 177 {
 178         void __user *argp = (void __user *)arg;
 179         int __user *p = argp;
 180         static const 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, sizeof(ident)) ? -EFAULT : 0;
 191
 192         case WDIOC_GETSTATUS:
 193         case WDIOC_GETBOOTSTATUS:
 194                 return put_user(0, p);
 195         case WDIOC_SETOPTIONS:
 196         {
 197                 int new_options, retval = -EINVAL;
 198
 199                 if (get_user(new_options, p))
 200                         return -EFAULT;
 201                 if (new_options & WDIOS_DISABLECARD) {
 202                         ali_stop();
 203                         retval = 0;
 204                 }
 205                 if (new_options & WDIOS_ENABLECARD) {
 206                         ali_start();
 207                         retval = 0;
 208                 }
 209                 return retval;
 210         }
 211         case WDIOC_KEEPALIVE:
 212                 ali_keepalive();
 213                 return 0;
 214         case WDIOC_SETTIMEOUT:
 215         {
 216                 int new_timeout;
 217                 if (get_user(new_timeout, p))
 218                         return -EFAULT;
 219                 if (ali_settimer(new_timeout))
 220                         return -EINVAL;
 221                 ali_keepalive();
 222         }
 223                 fallthrough;
 224         case WDIOC_GETTIMEOUT:
 225                 return put_user(timeout, p);
 226         default:
 227                 return -ENOTTY;
 228         }
 229 }
 230
 231 /*
 232  *      ali_open        -       handle open of ali watchdog
 233  *      @inode: inode from VFS
 234  *      @file: file from VFS
 235  *
 236  *      Open the ALi watchdog device. Ensure only one person opens it
 237  *      at a time. Also start the watchdog running.
 238  */
 239
 240 static int ali_open(struct inode *inode, struct file *file)
 241 {
 242         /* /dev/watchdog can only be opened once */
 243         if (test_and_set_bit(0, &ali_is_open))
 244                 return -EBUSY;
 245
 246         /* Activate */
 247         ali_start();
 248         return stream_open(inode, file);
 249 }
 250
 251 /*
 252  *      ali_release     -       close an ALi watchdog
 253  *      @inode: inode from VFS
 254  *      @file: file from VFS
 255  *
 256  *      Close the ALi watchdog device. Actual shutdown of the timer
 257  *      only occurs if the magic sequence has been set.
 258  */
 259
 260 static int ali_release(struct inode *inode, struct file *file)
 261 {
 262         /*
 263          *      Shut off the timer.
 264          */
 265         if (ali_expect_release == 42)
 266                 ali_stop();
 267         else {
 268                 pr_crit("Unexpected close, not stopping watchdog!\n");
 269                 ali_keepalive();
 270         }
 271         clear_bit(0, &ali_is_open);
 272         ali_expect_release = 0;
 273         return 0;
 274 }
 275
 276 /*
 277  *      ali_notify_sys  -       System down notifier
 278  *
 279  *      Notifier for system down
 280  */
 281
 282
 283 static int ali_notify_sys(struct notifier_block *this,
 284                                         unsigned long code, void *unused)
 285 {
 286         if (code == SYS_DOWN || code == SYS_HALT)
 287                 ali_stop();             /* Turn the WDT off */
 288         return NOTIFY_DONE;
 289 }
 290
 291 /*
 292  *      Data for PCI driver interface
 293  *
 294  *      This data only exists for exporting the supported
 295  *      PCI ids via MODULE_DEVICE_TABLE.  We do not actually
 296  *      register a pci_driver, because someone else might one day
 297  *      want to register another driver on the same PCI id.
 298  */
 299
 300 static const struct pci_device_id ali_pci_tbl[] __used = {
 301         { PCI_VENDOR_ID_AL, 0x1533, PCI_ANY_ID, PCI_ANY_ID,},
 302         { PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,},
 303         { 0, },
 304 };
 305 MODULE_DEVICE_TABLE(pci, ali_pci_tbl);
 306
 307 /*
 308  *      ali_find_watchdog       -       find a 1535 and 7101
 309  *
 310  *      Scans the PCI hardware for a 1535 series bridge and matching 7101
 311  *      watchdog device. This may be overtight but it is better to be safe
 312  */
 313
 314 static int __init ali_find_watchdog(void)
 315 {
 316         struct pci_dev *pdev;
 317         u32 wdog;
 318
 319         /* Check for a 1533/1535 series bridge */
 320         pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL);
 321         if (pdev == NULL)
 322                 pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1533, NULL);
 323         if (pdev == NULL)
 324                 return -ENODEV;
 325         pci_dev_put(pdev);
 326
 327         /* Check for the a 7101 PMU */
 328         pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL);
 329         if (pdev == NULL)
 330                 return -ENODEV;
 331
 332         if (pci_enable_device(pdev)) {
 333                 pci_dev_put(pdev);
 334                 return -EIO;
 335         }
 336
 337         ali_pci = pdev;
 338
 339         /*
 340          *      Initialize the timer bits
 341          */
 342         pci_read_config_dword(pdev, 0xCC, &wdog);
 343
 344         /* Timer bits */
 345         wdog &= ~0x3F;
 346         /* Issued events */
 347         wdog &= ~((1 << 27)|(1 << 26)|(1 << 25)|(1 << 24));
 348         /* No monitor bits */
 349         wdog &= ~((1 << 16)|(1 << 13)|(1 << 12)|(1 << 11)|(1 << 10)|(1 << 9));
 350
 351         pci_write_config_dword(pdev, 0xCC, wdog);
 352
 353         return 0;
 354 }
 355
 356 /*
 357  *      Kernel Interfaces
 358  */
 359
 360 static const struct file_operations ali_fops = {
 361         .owner          =       THIS_MODULE,
 362         .llseek         =       no_llseek,
 363         .write          =       ali_write,
 364         .unlocked_ioctl =       ali_ioctl,
 365         .compat_ioctl   =       compat_ptr_ioctl,
 366         .open           =       ali_open,
 367         .release        =       ali_release,
 368 };
 369
 370 static struct miscdevice ali_miscdev = {
 371         .minor =        WATCHDOG_MINOR,
 372         .name =         "watchdog",
 373         .fops =         &ali_fops,
 374 };
 375
 376 static struct notifier_block ali_notifier = {
 377         .notifier_call =        ali_notify_sys,
 378 };
 379
 380 /*
 381  *      watchdog_init   -       module initialiser
 382  *
 383  *      Scan for a suitable watchdog and if so initialize it. Return an error
 384  *      if we cannot, the error causes the module to unload
 385  */
 386
 387 static int __init watchdog_init(void)
 388 {
 389         int ret;
 390
 391         /* Check whether or not the hardware watchdog is there */
 392         if (ali_find_watchdog() != 0)
 393                 return -ENODEV;
 394
 395         /* Check that the timeout value is within it's range;
 396            if not reset to the default */
 397         if (timeout < 1 || timeout >= 18000) {
 398                 timeout = WATCHDOG_TIMEOUT;
 399                 pr_info("timeout value must be 0 < timeout < 18000, using %d\n",
 400                         timeout);
 401         }
 402
 403         /* Calculate the watchdog's timeout */
 404         ali_settimer(timeout);
 405
 406         ret = register_reboot_notifier(&ali_notifier);
 407         if (ret != 0) {
 408                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 409                 goto out;
 410         }
 411
 412         ret = misc_register(&ali_miscdev);
 413         if (ret != 0) {
 414                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 415                        WATCHDOG_MINOR, ret);
 416                 goto unreg_reboot;
 417         }
 418
 419         pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
 420                 timeout, nowayout);
 421
 422 out:
 423         return ret;
 424 unreg_reboot:
 425         unregister_reboot_notifier(&ali_notifier);
 426         goto out;
 427 }
 428
 429 /*
 430  *      watchdog_exit   -       module de-initialiser
 431  *
 432  *      Called while unloading a successfully installed watchdog module.
 433  */
 434
 435 static void __exit watchdog_exit(void)
 436 {
 437         /* Stop the timer before we leave */
 438         ali_stop();
 439
 440         /* Deregister */
 441         misc_deregister(&ali_miscdev);
 442         unregister_reboot_notifier(&ali_notifier);
 443         pci_dev_put(ali_pci);
 444 }
 445
 446 module_init(watchdog_init);
 447 module_exit(watchdog_exit);
 448
 449 MODULE_AUTHOR("Alan Cox");
 450 MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
 451 MODULE_LICENSE("GPL");