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