drivers/watchdog/cpwd.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* cpwd.c - driver implementation for hardware watchdog
   3  * timers found on Sun Microsystems CP1400 and CP1500 boards.
   4  *
   5  * This device supports both the generic Linux watchdog
   6  * interface and Solaris-compatible ioctls as best it is
   7  * able.
   8  *
   9  * NOTE:        CP1400 systems appear to have a defective intr_mask
  10  *                      register on the PLD, preventing the disabling of
  11  *                      timer interrupts.  We use a timer to periodically
  12  *                      reset 'stopped' watchdogs on affected platforms.
  13  *
  14  * Copyright (c) 2000 Eric Brower (ebrower@usa.net)
  15  * Copyright (C) 2008 David S. Miller <davem@davemloft.net>
  16  */
  17
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/fs.h>
  23 #include <linux/errno.h>
  24 #include <linux/major.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/ioport.h>
  28 #include <linux/timer.h>
  29 #include <linux/compat.h>
  30 #include <linux/slab.h>
  31 #include <linux/mutex.h>
  32 #include <linux/io.h>
  33 #include <linux/of.h>
  34 #include <linux/of_device.h>
  35 #include <linux/uaccess.h>
  36
  37 #include <asm/irq.h>
  38 #include <asm/watchdog.h>
  39
  40 #define DRIVER_NAME     "cpwd"
  41
  42 #define WD_OBPNAME      "watchdog"
  43 #define WD_BADMODEL     "SUNW,501-5336"
  44 #define WD_BTIMEOUT     (jiffies + (HZ * 1000))
  45 #define WD_BLIMIT       0xFFFF
  46
  47 #define WD0_MINOR       212
  48 #define WD1_MINOR       213
  49 #define WD2_MINOR       214
  50
  51 /* Internal driver definitions.  */
  52 #define WD0_ID                  0
  53 #define WD1_ID                  1
  54 #define WD2_ID                  2
  55 #define WD_NUMDEVS              3
  56
  57 #define WD_INTR_OFF             0
  58 #define WD_INTR_ON              1
  59
  60 #define WD_STAT_INIT    0x01    /* Watchdog timer is initialized        */
  61 #define WD_STAT_BSTOP   0x02    /* Watchdog timer is brokenstopped      */
  62 #define WD_STAT_SVCD    0x04    /* Watchdog interrupt occurred          */
  63
  64 /* Register value definitions
  65  */
  66 #define WD0_INTR_MASK   0x01    /* Watchdog device interrupt masks      */
  67 #define WD1_INTR_MASK   0x02
  68 #define WD2_INTR_MASK   0x04
  69
  70 #define WD_S_RUNNING    0x01    /* Watchdog device status running       */
  71 #define WD_S_EXPIRED    0x02    /* Watchdog device status expired       */
  72
  73 struct cpwd {
  74         void __iomem    *regs;
  75         spinlock_t      lock;
  76
  77         unsigned int    irq;
  78
  79         unsigned long   timeout;
  80         bool            enabled;
  81         bool            reboot;
  82         bool            broken;
  83         bool            initialized;
  84
  85         struct {
  86                 struct miscdevice       misc;
  87                 void __iomem            *regs;
  88                 u8                      intr_mask;
  89                 u8                      runstatus;
  90                 u16                     timeout;
  91         } devs[WD_NUMDEVS];
  92 };
  93
  94 static DEFINE_MUTEX(cpwd_mutex);
  95 static struct cpwd *cpwd_device;
  96
  97 /* Sun uses Altera PLD EPF8820ATC144-4
  98  * providing three hardware watchdogs:
  99  *
 100  * 1) RIC - sends an interrupt when triggered
 101  * 2) XIR - asserts XIR_B_RESET when triggered, resets CPU
 102  * 3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
 103  *
 104  *** Timer register block definition (struct wd_timer_regblk)
 105  *
 106  * dcntr and limit registers (halfword access):
 107  * -------------------
 108  * | 15 | ...| 1 | 0 |
 109  * -------------------
 110  * |-  counter val  -|
 111  * -------------------
 112  * dcntr -      Current 16-bit downcounter value.
 113  *                      When downcounter reaches '0' watchdog expires.
 114  *                      Reading this register resets downcounter with
 115  *                      'limit' value.
 116  * limit -      16-bit countdown value in 1/10th second increments.
 117  *                      Writing this register begins countdown with input value.
 118  *                      Reading from this register does not affect counter.
 119  * NOTES:       After watchdog reset, dcntr and limit contain '1'
 120  *
 121  * status register (byte access):
 122  * ---------------------------
 123  * | 7 | ... | 2 |  1  |  0  |
 124  * --------------+------------
 125  * |-   UNUSED  -| EXP | RUN |
 126  * ---------------------------
 127  * status-      Bit 0 - Watchdog is running
 128  *                      Bit 1 - Watchdog has expired
 129  *
 130  *** PLD register block definition (struct wd_pld_regblk)
 131  *
 132  * intr_mask register (byte access):
 133  * ---------------------------------
 134  * | 7 | ... | 3 |  2  |  1  |  0  |
 135  * +-------------+------------------
 136  * |-   UNUSED  -| WD3 | WD2 | WD1 |
 137  * ---------------------------------
 138  * WD3 -  1 == Interrupt disabled for watchdog 3
 139  * WD2 -  1 == Interrupt disabled for watchdog 2
 140  * WD1 -  1 == Interrupt disabled for watchdog 1
 141  *
 142  * pld_status register (byte access):
 143  * UNKNOWN, MAGICAL MYSTERY REGISTER
 144  *
 145  */
 146 #define WD_TIMER_REGSZ  16
 147 #define WD0_OFF         0
 148 #define WD1_OFF         (WD_TIMER_REGSZ * 1)
 149 #define WD2_OFF         (WD_TIMER_REGSZ * 2)
 150 #define PLD_OFF         (WD_TIMER_REGSZ * 3)
 151
 152 #define WD_DCNTR        0x00
 153 #define WD_LIMIT        0x04
 154 #define WD_STATUS       0x08
 155
 156 #define PLD_IMASK       (PLD_OFF + 0x00)
 157 #define PLD_STATUS      (PLD_OFF + 0x04)
 158
 159 static struct timer_list cpwd_timer;
 160
 161 static int wd0_timeout;
 162 static int wd1_timeout;
 163 static int wd2_timeout;
 164
 165 module_param(wd0_timeout, int, 0);
 166 MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
 167 module_param(wd1_timeout, int, 0);
 168 MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
 169 module_param(wd2_timeout, int, 0);
 170 MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");
 171
 172 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
 173 MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
 174 MODULE_LICENSE("GPL");
 175 MODULE_SUPPORTED_DEVICE("watchdog");
 176
 177 static void cpwd_writew(u16 val, void __iomem *addr)
 178 {
 179         writew(cpu_to_le16(val), addr);
 180 }
 181 static u16 cpwd_readw(void __iomem *addr)
 182 {
 183         u16 val = readw(addr);
 184
 185         return le16_to_cpu(val);
 186 }
 187
 188 static void cpwd_writeb(u8 val, void __iomem *addr)
 189 {
 190         writeb(val, addr);
 191 }
 192
 193 static u8 cpwd_readb(void __iomem *addr)
 194 {
 195         return readb(addr);
 196 }
 197
 198 /* Enable or disable watchdog interrupts
 199  * Because of the CP1400 defect this should only be
 200  * called during initialzation or by wd_[start|stop]timer()
 201  *
 202  * index        - sub-device index, or -1 for 'all'
 203  * enable       - non-zero to enable interrupts, zero to disable
 204  */
 205 static void cpwd_toggleintr(struct cpwd *p, int index, int enable)
 206 {
 207         unsigned char curregs = cpwd_readb(p->regs + PLD_IMASK);
 208         unsigned char setregs =
 209                 (index == -1) ?
 210                 (WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) :
 211                 (p->devs[index].intr_mask);
 212
 213         if (enable == WD_INTR_ON)
 214                 curregs &= ~setregs;
 215         else
 216                 curregs |= setregs;
 217
 218         cpwd_writeb(curregs, p->regs + PLD_IMASK);
 219 }
 220
 221 /* Restarts timer with maximum limit value and
 222  * does not unset 'brokenstop' value.
 223  */
 224 static void cpwd_resetbrokentimer(struct cpwd *p, int index)
 225 {
 226         cpwd_toggleintr(p, index, WD_INTR_ON);
 227         cpwd_writew(WD_BLIMIT, p->devs[index].regs + WD_LIMIT);
 228 }
 229
 230 /* Timer method called to reset stopped watchdogs--
 231  * because of the PLD bug on CP1400, we cannot mask
 232  * interrupts within the PLD so me must continually
 233  * reset the timers ad infinitum.
 234  */
 235 static void cpwd_brokentimer(struct timer_list *unused)
 236 {
 237         struct cpwd *p = cpwd_device;
 238         int id, tripped = 0;
 239
 240         /* kill a running timer instance, in case we
 241          * were called directly instead of by kernel timer
 242          */
 243         if (timer_pending(&cpwd_timer))
 244                 del_timer(&cpwd_timer);
 245
 246         for (id = 0; id < WD_NUMDEVS; id++) {
 247                 if (p->devs[id].runstatus & WD_STAT_BSTOP) {
 248                         ++tripped;
 249                         cpwd_resetbrokentimer(p, id);
 250                 }
 251         }
 252
 253         if (tripped) {
 254                 /* there is at least one timer brokenstopped-- reschedule */
 255                 cpwd_timer.expires = WD_BTIMEOUT;
 256                 add_timer(&cpwd_timer);
 257         }
 258 }
 259
 260 /* Reset countdown timer with 'limit' value and continue countdown.
 261  * This will not start a stopped timer.
 262  */
 263 static void cpwd_pingtimer(struct cpwd *p, int index)
 264 {
 265         if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING)
 266                 cpwd_readw(p->devs[index].regs + WD_DCNTR);
 267 }
 268
 269 /* Stop a running watchdog timer-- the timer actually keeps
 270  * running, but the interrupt is masked so that no action is
 271  * taken upon expiration.
 272  */
 273 static void cpwd_stoptimer(struct cpwd *p, int index)
 274 {
 275         if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING) {
 276                 cpwd_toggleintr(p, index, WD_INTR_OFF);
 277
 278                 if (p->broken) {
 279                         p->devs[index].runstatus |= WD_STAT_BSTOP;
 280                         cpwd_brokentimer(NULL);
 281                 }
 282         }
 283 }
 284
 285 /* Start a watchdog timer with the specified limit value
 286  * If the watchdog is running, it will be restarted with
 287  * the provided limit value.
 288  *
 289  * This function will enable interrupts on the specified
 290  * watchdog.
 291  */
 292 static void cpwd_starttimer(struct cpwd *p, int index)
 293 {
 294         if (p->broken)
 295                 p->devs[index].runstatus &= ~WD_STAT_BSTOP;
 296
 297         p->devs[index].runstatus &= ~WD_STAT_SVCD;
 298
 299         cpwd_writew(p->devs[index].timeout, p->devs[index].regs + WD_LIMIT);
 300         cpwd_toggleintr(p, index, WD_INTR_ON);
 301 }
 302
 303 static int cpwd_getstatus(struct cpwd *p, int index)
 304 {
 305         unsigned char stat = cpwd_readb(p->devs[index].regs + WD_STATUS);
 306         unsigned char intr = cpwd_readb(p->devs[index].regs + PLD_IMASK);
 307         unsigned char ret  = WD_STOPPED;
 308
 309         /* determine STOPPED */
 310         if (!stat)
 311                 return ret;
 312
 313         /* determine EXPIRED vs FREERUN vs RUNNING */
 314         else if (WD_S_EXPIRED & stat) {
 315                 ret = WD_EXPIRED;
 316         } else if (WD_S_RUNNING & stat) {
 317                 if (intr & p->devs[index].intr_mask) {
 318                         ret = WD_FREERUN;
 319                 } else {
 320                         /* Fudge WD_EXPIRED status for defective CP1400--
 321                          * IF timer is running
 322                          *      AND brokenstop is set
 323                          *      AND an interrupt has been serviced
 324                          * we are WD_EXPIRED.
 325                          *
 326                          * IF timer is running
 327                          *      AND brokenstop is set
 328                          *      AND no interrupt has been serviced
 329                          * we are WD_FREERUN.
 330                          */
 331                         if (p->broken &&
 332                             (p->devs[index].runstatus & WD_STAT_BSTOP)) {
 333                                 if (p->devs[index].runstatus & WD_STAT_SVCD) {
 334                                         ret = WD_EXPIRED;
 335                                 } else {
 336                                         /* we could as well pretend
 337                                          * we are expired */
 338                                         ret = WD_FREERUN;
 339                                 }
 340                         } else {
 341                                 ret = WD_RUNNING;
 342                         }
 343                 }
 344         }
 345
 346         /* determine SERVICED */
 347         if (p->devs[index].runstatus & WD_STAT_SVCD)
 348                 ret |= WD_SERVICED;
 349
 350         return ret;
 351 }
 352
 353 static irqreturn_t cpwd_interrupt(int irq, void *dev_id)
 354 {
 355         struct cpwd *p = dev_id;
 356
 357         /* Only WD0 will interrupt-- others are NMI and we won't
 358          * see them here....
 359          */
 360         spin_lock_irq(&p->lock);
 361
 362         cpwd_stoptimer(p, WD0_ID);
 363         p->devs[WD0_ID].runstatus |=  WD_STAT_SVCD;
 364
 365         spin_unlock_irq(&p->lock);
 366
 367         return IRQ_HANDLED;
 368 }
 369
 370 static int cpwd_open(struct inode *inode, struct file *f)
 371 {
 372         struct cpwd *p = cpwd_device;
 373
 374         mutex_lock(&cpwd_mutex);
 375         switch (iminor(inode)) {
 376         case WD0_MINOR:
 377         case WD1_MINOR:
 378         case WD2_MINOR:
 379                 break;
 380
 381         default:
 382                 mutex_unlock(&cpwd_mutex);
 383                 return -ENODEV;
 384         }
 385
 386         /* Register IRQ on first open of device */
 387         if (!p->initialized) {
 388                 if (request_irq(p->irq, &cpwd_interrupt,
 389                                 IRQF_SHARED, DRIVER_NAME, p)) {
 390                         pr_err("Cannot register IRQ %d\n", p->irq);
 391                         mutex_unlock(&cpwd_mutex);
 392                         return -EBUSY;
 393                 }
 394                 p->initialized = true;
 395         }
 396
 397         mutex_unlock(&cpwd_mutex);
 398
 399         return stream_open(inode, f);
 400 }
 401
 402 static int cpwd_release(struct inode *inode, struct file *file)
 403 {
 404         return 0;
 405 }
 406
 407 static long cpwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 408 {
 409         static const struct watchdog_info info = {
 410                 .options                = WDIOF_SETTIMEOUT,
 411                 .firmware_version       = 1,
 412                 .identity               = DRIVER_NAME,
 413         };
 414         void __user *argp = (void __user *)arg;
 415         struct inode *inode = file_inode(file);
 416         int index = iminor(inode) - WD0_MINOR;
 417         struct cpwd *p = cpwd_device;
 418         int setopt = 0;
 419
 420         switch (cmd) {
 421         /* Generic Linux IOCTLs */
 422         case WDIOC_GETSUPPORT:
 423                 if (copy_to_user(argp, &info, sizeof(struct watchdog_info)))
 424                         return -EFAULT;
 425                 break;
 426
 427         case WDIOC_GETSTATUS:
 428         case WDIOC_GETBOOTSTATUS:
 429                 if (put_user(0, (int __user *)argp))
 430                         return -EFAULT;
 431                 break;
 432
 433         case WDIOC_KEEPALIVE:
 434                 cpwd_pingtimer(p, index);
 435                 break;
 436
 437         case WDIOC_SETOPTIONS:
 438                 if (copy_from_user(&setopt, argp, sizeof(unsigned int)))
 439                         return -EFAULT;
 440
 441                 if (setopt & WDIOS_DISABLECARD) {
 442                         if (p->enabled)
 443                                 return -EINVAL;
 444                         cpwd_stoptimer(p, index);
 445                 } else if (setopt & WDIOS_ENABLECARD) {
 446                         cpwd_starttimer(p, index);
 447                 } else {
 448                         return -EINVAL;
 449                 }
 450                 break;
 451
 452         /* Solaris-compatible IOCTLs */
 453         case WIOCGSTAT:
 454                 setopt = cpwd_getstatus(p, index);
 455                 if (copy_to_user(argp, &setopt, sizeof(unsigned int)))
 456                         return -EFAULT;
 457                 break;
 458
 459         case WIOCSTART:
 460                 cpwd_starttimer(p, index);
 461                 break;
 462
 463         case WIOCSTOP:
 464                 if (p->enabled)
 465                         return -EINVAL;
 466
 467                 cpwd_stoptimer(p, index);
 468                 break;
 469
 470         default:
 471                 return -EINVAL;
 472         }
 473
 474         return 0;
 475 }
 476
 477 static long cpwd_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 478 {
 479         return cpwd_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
 480 }
 481
 482 static ssize_t cpwd_write(struct file *file, const char __user *buf,
 483                           size_t count, loff_t *ppos)
 484 {
 485         struct inode *inode = file_inode(file);
 486         struct cpwd *p = cpwd_device;
 487         int index = iminor(inode);
 488
 489         if (count) {
 490                 cpwd_pingtimer(p, index);
 491                 return 1;
 492         }
 493
 494         return 0;
 495 }
 496
 497 static ssize_t cpwd_read(struct file *file, char __user *buffer,
 498                          size_t count, loff_t *ppos)
 499 {
 500         return -EINVAL;
 501 }
 502
 503 static const struct file_operations cpwd_fops = {
 504         .owner =                THIS_MODULE,
 505         .unlocked_ioctl =       cpwd_ioctl,
 506         .compat_ioctl =         cpwd_compat_ioctl,
 507         .open =                 cpwd_open,
 508         .write =                cpwd_write,
 509         .read =                 cpwd_read,
 510         .release =              cpwd_release,
 511         .llseek =               no_llseek,
 512 };
 513
 514 static int cpwd_probe(struct platform_device *op)
 515 {
 516         struct device_node *options;
 517         const char *str_prop;
 518         const void *prop_val;
 519         int i, err = -EINVAL;
 520         struct cpwd *p;
 521
 522         if (cpwd_device)
 523                 return -EINVAL;
 524
 525         p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
 526         if (!p)
 527                 return -ENOMEM;
 528
 529         p->irq = op->archdata.irqs[0];
 530
 531         spin_lock_init(&p->lock);
 532
 533         p->regs = of_ioremap(&op->resource[0], 0,
 534                              4 * WD_TIMER_REGSZ, DRIVER_NAME);
 535         if (!p->regs) {
 536                 pr_err("Unable to map registers\n");
 537                 return -ENOMEM;
 538         }
 539
 540         options = of_find_node_by_path("/options");
 541         if (!options) {
 542                 err = -ENODEV;
 543                 pr_err("Unable to find /options node\n");
 544                 goto out_iounmap;
 545         }
 546
 547         prop_val = of_get_property(options, "watchdog-enable?", NULL);
 548         p->enabled = (prop_val ? true : false);
 549
 550         prop_val = of_get_property(options, "watchdog-reboot?", NULL);
 551         p->reboot = (prop_val ? true : false);
 552
 553         str_prop = of_get_property(options, "watchdog-timeout", NULL);
 554         if (str_prop)
 555                 p->timeout = simple_strtoul(str_prop, NULL, 10);
 556
 557         of_node_put(options);
 558
 559         /* CP1400s seem to have broken PLD implementations-- the
 560          * interrupt_mask register cannot be written, so no timer
 561          * interrupts can be masked within the PLD.
 562          */
 563         str_prop = of_get_property(op->dev.of_node, "model", NULL);
 564         p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));
 565
 566         if (!p->enabled)
 567                 cpwd_toggleintr(p, -1, WD_INTR_OFF);
 568
 569         for (i = 0; i < WD_NUMDEVS; i++) {
 570                 static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
 571                 static int *parms[] = { &wd0_timeout,
 572                                         &wd1_timeout,
 573                                         &wd2_timeout };
 574                 struct miscdevice *mp = &p->devs[i].misc;
 575
 576                 mp->minor = WD0_MINOR + i;
 577                 mp->name = cpwd_names[i];
 578                 mp->fops = &cpwd_fops;
 579
 580                 p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
 581                 p->devs[i].intr_mask = (WD0_INTR_MASK << i);
 582                 p->devs[i].runstatus &= ~WD_STAT_BSTOP;
 583                 p->devs[i].runstatus |= WD_STAT_INIT;
 584                 p->devs[i].timeout = p->timeout;
 585                 if (*parms[i])
 586                         p->devs[i].timeout = *parms[i];
 587
 588                 err = misc_register(&p->devs[i].misc);
 589                 if (err) {
 590                         pr_err("Could not register misc device for dev %d\n",
 591                                i);
 592                         goto out_unregister;
 593                 }
 594         }
 595
 596         if (p->broken) {
 597                 timer_setup(&cpwd_timer, cpwd_brokentimer, 0);
 598                 cpwd_timer.expires      = WD_BTIMEOUT;
 599
 600                 pr_info("PLD defect workaround enabled for model %s\n",
 601                         WD_BADMODEL);
 602         }
 603
 604         platform_set_drvdata(op, p);
 605         cpwd_device = p;
 606         return 0;
 607
 608 out_unregister:
 609         for (i--; i >= 0; i--)
 610                 misc_deregister(&p->devs[i].misc);
 611
 612 out_iounmap:
 613         of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
 614
 615         return err;
 616 }
 617
 618 static int cpwd_remove(struct platform_device *op)
 619 {
 620         struct cpwd *p = platform_get_drvdata(op);
 621         int i;
 622
 623         for (i = 0; i < WD_NUMDEVS; i++) {
 624                 misc_deregister(&p->devs[i].misc);
 625
 626                 if (!p->enabled) {
 627                         cpwd_stoptimer(p, i);
 628                         if (p->devs[i].runstatus & WD_STAT_BSTOP)
 629                                 cpwd_resetbrokentimer(p, i);
 630                 }
 631         }
 632
 633         if (p->broken)
 634                 del_timer_sync(&cpwd_timer);
 635
 636         if (p->initialized)
 637                 free_irq(p->irq, p);
 638
 639         of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
 640
 641         cpwd_device = NULL;
 642
 643         return 0;
 644 }
 645
 646 static const struct of_device_id cpwd_match[] = {
 647         {
 648                 .name = "watchdog",
 649         },
 650         {},
 651 };
 652 MODULE_DEVICE_TABLE(of, cpwd_match);
 653
 654 static struct platform_driver cpwd_driver = {
 655         .driver = {
 656                 .name = DRIVER_NAME,
 657                 .of_match_table = cpwd_match,
 658         },
 659         .probe          = cpwd_probe,
 660         .remove         = cpwd_remove,
 661 };
 662
 663 module_platform_driver(cpwd_driver);