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   1 /* cpwd.c - driver implementation for hardware watchdog
   2  * timers found on Sun Microsystems CP1400 and CP1500 boards.
   3  *
   4  * This device supports both the generic Linux watchdog
   5  * interface and Solaris-compatible ioctls as best it is
   6  * able.
   7  *
   8  * NOTE:        CP1400 systems appear to have a defective intr_mask
   9  *                      register on the PLD, preventing the disabling of
  10  *                      timer interrupts.  We use a timer to periodically
  11  *                      reset 'stopped' watchdogs on affected platforms.
  12  *
  13  * Copyright (c) 2000 Eric Brower (ebrower@usa.net)
  14  * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/fs.h>
  20 #include <linux/errno.h>
  21 #include <linux/major.h>
  22 #include <linux/init.h>
  23 #include <linux/miscdevice.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/ioport.h>
  26 #include <linux/timer.h>
  27 #include <linux/smp_lock.h>
  28 #include <linux/io.h>
  29 #include <linux/of.h>
  30 #include <linux/of_device.h>
  31 #include <linux/uaccess.h>
  32
  33 #include <asm/irq.h>
  34 #include <asm/watchdog.h>
  35
  36 #define DRIVER_NAME     "cpwd"
  37 #define PFX             DRIVER_NAME ": "
  38
  39 #define WD_OBPNAME      "watchdog"
  40 #define WD_BADMODEL     "SUNW,501-5336"
  41 #define WD_BTIMEOUT     (jiffies + (HZ * 1000))
  42 #define WD_BLIMIT       0xFFFF
  43
  44 #define WD0_MINOR       212
  45 #define WD1_MINOR       213
  46 #define WD2_MINOR       214
  47
  48 /* Internal driver definitions.  */
  49 #define WD0_ID                  0
  50 #define WD1_ID                  1
  51 #define WD2_ID                  2
  52 #define WD_NUMDEVS              3
  53
  54 #define WD_INTR_OFF             0
  55 #define WD_INTR_ON              1
  56
  57 #define WD_STAT_INIT    0x01    /* Watchdog timer is initialized        */
  58 #define WD_STAT_BSTOP   0x02    /* Watchdog timer is brokenstopped      */
  59 #define WD_STAT_SVCD    0x04    /* Watchdog interrupt occurred          */
  60
  61 /* Register value definitions
  62  */
  63 #define WD0_INTR_MASK   0x01    /* Watchdog device interrupt masks      */
  64 #define WD1_INTR_MASK   0x02
  65 #define WD2_INTR_MASK   0x04
  66
  67 #define WD_S_RUNNING    0x01    /* Watchdog device status running       */
  68 #define WD_S_EXPIRED    0x02    /* Watchdog device status expired       */
  69
  70 struct cpwd {
  71         void __iomem    *regs;
  72         spinlock_t      lock;
  73
  74         unsigned int    irq;
  75
  76         unsigned long   timeout;
  77         bool            enabled;
  78         bool            reboot;
  79         bool            broken;
  80         bool            initialized;
  81
  82         struct {
  83                 struct miscdevice       misc;
  84                 void __iomem            *regs;
  85                 u8                      intr_mask;
  86                 u8                      runstatus;
  87                 u16                     timeout;
  88         } devs[WD_NUMDEVS];
  89 };
  90
  91 static struct cpwd *cpwd_device;
  92
  93 /* Sun uses Altera PLD EPF8820ATC144-4
  94  * providing three hardware watchdogs:
  95  *
  96  * 1) RIC - sends an interrupt when triggered
  97  * 2) XIR - asserts XIR_B_RESET when triggered, resets CPU
  98  * 3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
  99  *
 100  *** Timer register block definition (struct wd_timer_regblk)
 101  *
 102  * dcntr and limit registers (halfword access):
 103  * -------------------
 104  * | 15 | ...| 1 | 0 |
 105  * -------------------
 106  * |-  counter val  -|
 107  * -------------------
 108  * dcntr -      Current 16-bit downcounter value.
 109  *                      When downcounter reaches '0' watchdog expires.
 110  *                      Reading this register resets downcounter with
 111  *                      'limit' value.
 112  * limit -      16-bit countdown value in 1/10th second increments.
 113  *                      Writing this register begins countdown with input value.
 114  *                      Reading from this register does not affect counter.
 115  * NOTES:       After watchdog reset, dcntr and limit contain '1'
 116  *
 117  * status register (byte access):
 118  * ---------------------------
 119  * | 7 | ... | 2 |  1  |  0  |
 120  * --------------+------------
 121  * |-   UNUSED  -| EXP | RUN |
 122  * ---------------------------
 123  * status-      Bit 0 - Watchdog is running
 124  *                      Bit 1 - Watchdog has expired
 125  *
 126  *** PLD register block definition (struct wd_pld_regblk)
 127  *
 128  * intr_mask register (byte access):
 129  * ---------------------------------
 130  * | 7 | ... | 3 |  2  |  1  |  0  |
 131  * +-------------+------------------
 132  * |-   UNUSED  -| WD3 | WD2 | WD1 |
 133  * ---------------------------------
 134  * WD3 -  1 == Interrupt disabled for watchdog 3
 135  * WD2 -  1 == Interrupt disabled for watchdog 2
 136  * WD1 -  1 == Interrupt disabled for watchdog 1
 137  *
 138  * pld_status register (byte access):
 139  * UNKNOWN, MAGICAL MYSTERY REGISTER
 140  *
 141  */
 142 #define WD_TIMER_REGSZ  16
 143 #define WD0_OFF         0
 144 #define WD1_OFF         (WD_TIMER_REGSZ * 1)
 145 #define WD2_OFF         (WD_TIMER_REGSZ * 2)
 146 #define PLD_OFF         (WD_TIMER_REGSZ * 3)
 147
 148 #define WD_DCNTR        0x00
 149 #define WD_LIMIT        0x04
 150 #define WD_STATUS       0x08
 151
 152 #define PLD_IMASK       (PLD_OFF + 0x00)
 153 #define PLD_STATUS      (PLD_OFF + 0x04)
 154
 155 static struct timer_list cpwd_timer;
 156
 157 static int wd0_timeout;
 158 static int wd1_timeout;
 159 static int wd2_timeout;
 160
 161 module_param(wd0_timeout, int, 0);
 162 MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
 163 module_param(wd1_timeout, int, 0);
 164 MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
 165 module_param(wd2_timeout, int, 0);
 166 MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");
 167
 168 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
 169 MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
 170 MODULE_LICENSE("GPL");
 171 MODULE_SUPPORTED_DEVICE("watchdog");
 172
 173 static void cpwd_writew(u16 val, void __iomem *addr)
 174 {
 175         writew(cpu_to_le16(val), addr);
 176 }
 177 static u16 cpwd_readw(void __iomem *addr)
 178 {
 179         u16 val = readw(addr);
 180
 181         return le16_to_cpu(val);
 182 }
 183
 184 static void cpwd_writeb(u8 val, void __iomem *addr)
 185 {
 186         writeb(val, addr);
 187 }
 188
 189 static u8 cpwd_readb(void __iomem *addr)
 190 {
 191         return readb(addr);
 192 }
 193
 194 /* Enable or disable watchdog interrupts
 195  * Because of the CP1400 defect this should only be
 196  * called during initialzation or by wd_[start|stop]timer()
 197  *
 198  * index        - sub-device index, or -1 for 'all'
 199  * enable       - non-zero to enable interrupts, zero to disable
 200  */
 201 static void cpwd_toggleintr(struct cpwd *p, int index, int enable)
 202 {
 203         unsigned char curregs = cpwd_readb(p->regs + PLD_IMASK);
 204         unsigned char setregs =
 205                 (index == -1) ?
 206                 (WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) :
 207                 (p->devs[index].intr_mask);
 208
 209         if (enable == WD_INTR_ON)
 210                 curregs &= ~setregs;
 211         else
 212                 curregs |= setregs;
 213
 214         cpwd_writeb(curregs, p->regs + PLD_IMASK);
 215 }
 216
 217 /* Restarts timer with maximum limit value and
 218  * does not unset 'brokenstop' value.
 219  */
 220 static void cpwd_resetbrokentimer(struct cpwd *p, int index)
 221 {
 222         cpwd_toggleintr(p, index, WD_INTR_ON);
 223         cpwd_writew(WD_BLIMIT, p->devs[index].regs + WD_LIMIT);
 224 }
 225
 226 /* Timer method called to reset stopped watchdogs--
 227  * because of the PLD bug on CP1400, we cannot mask
 228  * interrupts within the PLD so me must continually
 229  * reset the timers ad infinitum.
 230  */
 231 static void cpwd_brokentimer(unsigned long data)
 232 {
 233         struct cpwd *p = (struct cpwd *) data;
 234         int id, tripped = 0;
 235
 236         /* kill a running timer instance, in case we
 237          * were called directly instead of by kernel timer
 238          */
 239         if (timer_pending(&cpwd_timer))
 240                 del_timer(&cpwd_timer);
 241
 242         for (id = 0; id < WD_NUMDEVS; id++) {
 243                 if (p->devs[id].runstatus & WD_STAT_BSTOP) {
 244                         ++tripped;
 245                         cpwd_resetbrokentimer(p, id);
 246                 }
 247         }
 248
 249         if (tripped) {
 250                 /* there is at least one timer brokenstopped-- reschedule */
 251                 cpwd_timer.expires = WD_BTIMEOUT;
 252                 add_timer(&cpwd_timer);
 253         }
 254 }
 255
 256 /* Reset countdown timer with 'limit' value and continue countdown.
 257  * This will not start a stopped timer.
 258  */
 259 static void cpwd_pingtimer(struct cpwd *p, int index)
 260 {
 261         if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING)
 262                 cpwd_readw(p->devs[index].regs + WD_DCNTR);
 263 }
 264
 265 /* Stop a running watchdog timer-- the timer actually keeps
 266  * running, but the interrupt is masked so that no action is
 267  * taken upon expiration.
 268  */
 269 static void cpwd_stoptimer(struct cpwd *p, int index)
 270 {
 271         if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING) {
 272                 cpwd_toggleintr(p, index, WD_INTR_OFF);
 273
 274                 if (p->broken) {
 275                         p->devs[index].runstatus |= WD_STAT_BSTOP;
 276                         cpwd_brokentimer((unsigned long) p);
 277                 }
 278         }
 279 }
 280
 281 /* Start a watchdog timer with the specified limit value
 282  * If the watchdog is running, it will be restarted with
 283  * the provided limit value.
 284  *
 285  * This function will enable interrupts on the specified
 286  * watchdog.
 287  */
 288 static void cpwd_starttimer(struct cpwd *p, int index)
 289 {
 290         if (p->broken)
 291                 p->devs[index].runstatus &= ~WD_STAT_BSTOP;
 292
 293         p->devs[index].runstatus &= ~WD_STAT_SVCD;
 294
 295         cpwd_writew(p->devs[index].timeout, p->devs[index].regs + WD_LIMIT);
 296         cpwd_toggleintr(p, index, WD_INTR_ON);
 297 }
 298
 299 static int cpwd_getstatus(struct cpwd *p, int index)
 300 {
 301         unsigned char stat = cpwd_readb(p->devs[index].regs + WD_STATUS);
 302         unsigned char intr = cpwd_readb(p->devs[index].regs + PLD_IMASK);
 303         unsigned char ret  = WD_STOPPED;
 304
 305         /* determine STOPPED */
 306         if (!stat)
 307                 return ret;
 308
 309         /* determine EXPIRED vs FREERUN vs RUNNING */
 310         else if (WD_S_EXPIRED & stat) {
 311                 ret = WD_EXPIRED;
 312         } else if (WD_S_RUNNING & stat) {
 313                 if (intr & p->devs[index].intr_mask) {
 314                         ret = WD_FREERUN;
 315                 } else {
 316                         /* Fudge WD_EXPIRED status for defective CP1400--
 317                          * IF timer is running
 318                          *      AND brokenstop is set
 319                          *      AND an interrupt has been serviced
 320                          * we are WD_EXPIRED.
 321                          *
 322                          * IF timer is running
 323                          *      AND brokenstop is set
 324                          *      AND no interrupt has been serviced
 325                          * we are WD_FREERUN.
 326                          */
 327                         if (p->broken &&
 328                             (p->devs[index].runstatus & WD_STAT_BSTOP)) {
 329                                 if (p->devs[index].runstatus & WD_STAT_SVCD) {
 330                                         ret = WD_EXPIRED;
 331                                 } else {
 332                                         /* we could as well pretend
 333                                          * we are expired */
 334                                         ret = WD_FREERUN;
 335                                 }
 336                         } else {
 337                                 ret = WD_RUNNING;
 338                         }
 339                 }
 340         }
 341
 342         /* determine SERVICED */
 343         if (p->devs[index].runstatus & WD_STAT_SVCD)
 344                 ret |= WD_SERVICED;
 345
 346         return ret;
 347 }
 348
 349 static irqreturn_t cpwd_interrupt(int irq, void *dev_id)
 350 {
 351         struct cpwd *p = dev_id;
 352
 353         /* Only WD0 will interrupt-- others are NMI and we won't
 354          * see them here....
 355          */
 356         spin_lock_irq(&p->lock);
 357
 358         cpwd_stoptimer(p, WD0_ID);
 359         p->devs[WD0_ID].runstatus |=  WD_STAT_SVCD;
 360
 361         spin_unlock_irq(&p->lock);
 362
 363         return IRQ_HANDLED;
 364 }
 365
 366 static int cpwd_open(struct inode *inode, struct file *f)
 367 {
 368         struct cpwd *p = cpwd_device;
 369
 370         lock_kernel();
 371         switch (iminor(inode)) {
 372         case WD0_MINOR:
 373         case WD1_MINOR:
 374         case WD2_MINOR:
 375                 break;
 376
 377         default:
 378                 unlock_kernel();
 379                 return -ENODEV;
 380         }
 381
 382         /* Register IRQ on first open of device */
 383         if (!p->initialized) {
 384                 if (request_irq(p->irq, &cpwd_interrupt,
 385                                 IRQF_SHARED, DRIVER_NAME, p)) {
 386                         printk(KERN_ERR PFX "Cannot register IRQ %d\n",
 387                                 p->irq);
 388                         unlock_kernel();
 389                         return -EBUSY;
 390                 }
 391                 p->initialized = true;
 392         }
 393
 394         unlock_kernel();
 395
 396         return nonseekable_open(inode, f);
 397 }
 398
 399 static int cpwd_release(struct inode *inode, struct file *file)
 400 {
 401         return 0;
 402 }
 403
 404 static long cpwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 405 {
 406         static struct watchdog_info info = {
 407                 .options                = WDIOF_SETTIMEOUT,
 408                 .firmware_version       = 1,
 409                 .identity               = DRIVER_NAME,
 410         };
 411         void __user *argp = (void __user *)arg;
 412         struct inode *inode = file->f_path.dentry->d_inode;
 413         int index = iminor(inode) - WD0_MINOR;
 414         struct cpwd *p = cpwd_device;
 415         int setopt = 0;
 416
 417         switch (cmd) {
 418         /* Generic Linux IOCTLs */
 419         case WDIOC_GETSUPPORT:
 420                 if (copy_to_user(argp, &info, sizeof(struct watchdog_info)))
 421                         return -EFAULT;
 422                 break;
 423
 424         case WDIOC_GETSTATUS:
 425         case WDIOC_GETBOOTSTATUS:
 426                 if (put_user(0, (int __user *)argp))
 427                         return -EFAULT;
 428                 break;
 429
 430         case WDIOC_KEEPALIVE:
 431                 cpwd_pingtimer(p, index);
 432                 break;
 433
 434         case WDIOC_SETOPTIONS:
 435                 if (copy_from_user(&setopt, argp, sizeof(unsigned int)))
 436                         return -EFAULT;
 437
 438                 if (setopt & WDIOS_DISABLECARD) {
 439                         if (p->enabled)
 440                                 return -EINVAL;
 441                         cpwd_stoptimer(p, index);
 442                 } else if (setopt & WDIOS_ENABLECARD) {
 443                         cpwd_starttimer(p, index);
 444                 } else {
 445                         return -EINVAL;
 446                 }
 447                 break;
 448
 449         /* Solaris-compatible IOCTLs */
 450         case WIOCGSTAT:
 451                 setopt = cpwd_getstatus(p, index);
 452                 if (copy_to_user(argp, &setopt, sizeof(unsigned int)))
 453                         return -EFAULT;
 454                 break;
 455
 456         case WIOCSTART:
 457                 cpwd_starttimer(p, index);
 458                 break;
 459
 460         case WIOCSTOP:
 461                 if (p->enabled)
 462                         return -EINVAL;
 463
 464                 cpwd_stoptimer(p, index);
 465                 break;
 466
 467         default:
 468                 return -EINVAL;
 469         }
 470
 471         return 0;
 472 }
 473
 474 static long cpwd_compat_ioctl(struct file *file, unsigned int cmd,
 475                               unsigned long arg)
 476 {
 477         int rval = -ENOIOCTLCMD;
 478
 479         switch (cmd) {
 480         /* solaris ioctls are specific to this driver */
 481         case WIOCSTART:
 482         case WIOCSTOP:
 483         case WIOCGSTAT:
 484                 lock_kernel();
 485                 rval = cpwd_ioctl(file, cmd, arg);
 486                 unlock_kernel();
 487                 break;
 488
 489         /* everything else is handled by the generic compat layer */
 490         default:
 491                 break;
 492         }
 493
 494         return rval;
 495 }
 496
 497 static ssize_t cpwd_write(struct file *file, const char __user *buf,
 498                           size_t count, loff_t *ppos)
 499 {
 500         struct inode *inode = file->f_path.dentry->d_inode;
 501         struct cpwd *p = cpwd_device;
 502         int index = iminor(inode);
 503
 504         if (count) {
 505                 cpwd_pingtimer(p, index);
 506                 return 1;
 507         }
 508
 509         return 0;
 510 }
 511
 512 static ssize_t cpwd_read(struct file *file, char __user *buffer,
 513                          size_t count, loff_t *ppos)
 514 {
 515         return -EINVAL;
 516 }
 517
 518 static const struct file_operations cpwd_fops = {
 519         .owner =                THIS_MODULE,
 520         .unlocked_ioctl =       cpwd_ioctl,
 521         .compat_ioctl =         cpwd_compat_ioctl,
 522         .open =                 cpwd_open,
 523         .write =                cpwd_write,
 524         .read =                 cpwd_read,
 525         .release =              cpwd_release,
 526 };
 527
 528 static int __devinit cpwd_probe(struct of_device *op,
 529                                 const struct of_device_id *match)
 530 {
 531         struct device_node *options;
 532         const char *str_prop;
 533         const void *prop_val;
 534         int i, err = -EINVAL;
 535         struct cpwd *p;
 536
 537         if (cpwd_device)
 538                 return -EINVAL;
 539
 540         p = kzalloc(sizeof(*p), GFP_KERNEL);
 541         err = -ENOMEM;
 542         if (!p) {
 543                 printk(KERN_ERR PFX "Unable to allocate struct cpwd.\n");
 544                 goto out;
 545         }
 546
 547         p->irq = op->irqs[0];
 548
 549         spin_lock_init(&p->lock);
 550
 551         p->regs = of_ioremap(&op->resource[0], 0,
 552                              4 * WD_TIMER_REGSZ, DRIVER_NAME);
 553         if (!p->regs) {
 554                 printk(KERN_ERR PFX "Unable to map registers.\n");
 555                 goto out_free;
 556         }
 557
 558         options = of_find_node_by_path("/options");
 559         err = -ENODEV;
 560         if (!options) {
 561                 printk(KERN_ERR PFX "Unable to find /options node.\n");
 562                 goto out_iounmap;
 563         }
 564
 565         prop_val = of_get_property(options, "watchdog-enable?", NULL);
 566         p->enabled = (prop_val ? true : false);
 567
 568         prop_val = of_get_property(options, "watchdog-reboot?", NULL);
 569         p->reboot = (prop_val ? true : false);
 570
 571         str_prop = of_get_property(options, "watchdog-timeout", NULL);
 572         if (str_prop)
 573                 p->timeout = simple_strtoul(str_prop, NULL, 10);
 574
 575         /* CP1400s seem to have broken PLD implementations-- the
 576          * interrupt_mask register cannot be written, so no timer
 577          * interrupts can be masked within the PLD.
 578          */
 579         str_prop = of_get_property(op->node, "model", NULL);
 580         p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));
 581
 582         if (!p->enabled)
 583                 cpwd_toggleintr(p, -1, WD_INTR_OFF);
 584
 585         for (i = 0; i < WD_NUMDEVS; i++) {
 586                 static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
 587                 static int *parms[] = { &wd0_timeout,
 588                                         &wd1_timeout,
 589                                         &wd2_timeout };
 590                 struct miscdevice *mp = &p->devs[i].misc;
 591
 592                 mp->minor = WD0_MINOR + i;
 593                 mp->name = cpwd_names[i];
 594                 mp->fops = &cpwd_fops;
 595
 596                 p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
 597                 p->devs[i].intr_mask = (WD0_INTR_MASK << i);
 598                 p->devs[i].runstatus &= ~WD_STAT_BSTOP;
 599                 p->devs[i].runstatus |= WD_STAT_INIT;
 600                 p->devs[i].timeout = p->timeout;
 601                 if (*parms[i])
 602                         p->devs[i].timeout = *parms[i];
 603
 604                 err = misc_register(&p->devs[i].misc);
 605                 if (err) {
 606                         printk(KERN_ERR "Could not register misc device for "
 607                                "dev %d\n", i);
 608                         goto out_unregister;
 609                 }
 610         }
 611
 612         if (p->broken) {
 613                 init_timer(&cpwd_timer);
 614                 cpwd_timer.function     = cpwd_brokentimer;
 615                 cpwd_timer.data         = (unsigned long) p;
 616                 cpwd_timer.expires      = WD_BTIMEOUT;
 617
 618                 printk(KERN_INFO PFX "PLD defect workaround enabled for "
 619                        "model " WD_BADMODEL ".\n");
 620         }
 621
 622         dev_set_drvdata(&op->dev, p);
 623         cpwd_device = p;
 624         err = 0;
 625
 626 out:
 627         return err;
 628
 629 out_unregister:
 630         for (i--; i >= 0; i--)
 631                 misc_deregister(&p->devs[i].misc);
 632
 633 out_iounmap:
 634         of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
 635
 636 out_free:
 637         kfree(p);
 638         goto out;
 639 }
 640
 641 static int __devexit cpwd_remove(struct of_device *op)
 642 {
 643         struct cpwd *p = dev_get_drvdata(&op->dev);
 644         int i;
 645
 646         for (i = 0; i < 4; i++) {
 647                 misc_deregister(&p->devs[i].misc);
 648
 649                 if (!p->enabled) {
 650                         cpwd_stoptimer(p, i);
 651                         if (p->devs[i].runstatus & WD_STAT_BSTOP)
 652                                 cpwd_resetbrokentimer(p, i);
 653                 }
 654         }
 655
 656         if (p->broken)
 657                 del_timer_sync(&cpwd_timer);
 658
 659         if (p->initialized)
 660                 free_irq(p->irq, p);
 661
 662         of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
 663         kfree(p);
 664
 665         cpwd_device = NULL;
 666
 667         return 0;
 668 }
 669
 670 static const struct of_device_id cpwd_match[] = {
 671         {
 672                 .name = "watchdog",
 673         },
 674         {},
 675 };
 676 MODULE_DEVICE_TABLE(of, cpwd_match);
 677
 678 static struct of_platform_driver cpwd_driver = {
 679         .name           = DRIVER_NAME,
 680         .match_table    = cpwd_match,
 681         .probe          = cpwd_probe,
 682         .remove         = __devexit_p(cpwd_remove),
 683 };
 684
 685 static int __init cpwd_init(void)
 686 {
 687         return of_register_driver(&cpwd_driver, &of_bus_type);
 688 }
 689
 690 static void __exit cpwd_exit(void)
 691 {
 692         of_unregister_driver(&cpwd_driver);
 693 }
 694
 695 module_init(cpwd_init);
 696 module_exit(cpwd_exit);