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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 18 19 #include <linux/kernel.h> 20 #include <linux/module.h> 21 #include <linux/fs.h> 22 #include <linux/errno.h> 23 #include <linux/major.h> 24 #include <linux/init.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(unsigned long data) 235 { 236 struct cpwd *p = (struct cpwd *) data; 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((unsigned long) p); 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 nonseekable_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 long cpwd_compat_ioctl(struct file *file, unsigned int cmd, 477 unsigned long arg) 478 { 479 int rval = -ENOIOCTLCMD; 480 481 switch (cmd) { 482 /* solaris ioctls are specific to this driver */ 483 case WIOCSTART: 484 case WIOCSTOP: 485 case WIOCGSTAT: 486 mutex_lock(&cpwd_mutex); 487 rval = cpwd_ioctl(file, cmd, arg); 488 mutex_unlock(&cpwd_mutex); 489 break; 490 491 /* everything else is handled by the generic compat layer */ 492 default: 493 break; 494 } 495 496 return rval; 497 } 498 499 static ssize_t cpwd_write(struct file *file, const char __user *buf, 500 size_t count, loff_t *ppos) 501 { 502 struct inode *inode = file_inode(file); 503 struct cpwd *p = cpwd_device; 504 int index = iminor(inode); 505 506 if (count) { 507 cpwd_pingtimer(p, index); 508 return 1; 509 } 510 511 return 0; 512 } 513 514 static ssize_t cpwd_read(struct file *file, char __user *buffer, 515 size_t count, loff_t *ppos) 516 { 517 return -EINVAL; 518 } 519 520 static const struct file_operations cpwd_fops = { 521 .owner = THIS_MODULE, 522 .unlocked_ioctl = cpwd_ioctl, 523 .compat_ioctl = cpwd_compat_ioctl, 524 .open = cpwd_open, 525 .write = cpwd_write, 526 .read = cpwd_read, 527 .release = cpwd_release, 528 .llseek = no_llseek, 529 }; 530 531 static int cpwd_probe(struct platform_device *op) 532 { 533 struct device_node *options; 534 const char *str_prop; 535 const void *prop_val; 536 int i, err = -EINVAL; 537 struct cpwd *p; 538 539 if (cpwd_device) 540 return -EINVAL; 541 542 p = kzalloc(sizeof(*p), GFP_KERNEL); 543 err = -ENOMEM; 544 if (!p) { 545 pr_err("Unable to allocate struct cpwd\n"); 546 goto out; 547 } 548 549 p->irq = op->archdata.irqs[0]; 550 551 spin_lock_init(&p->lock); 552 553 p->regs = of_ioremap(&op->resource[0], 0, 554 4 * WD_TIMER_REGSZ, DRIVER_NAME); 555 if (!p->regs) { 556 pr_err("Unable to map registers\n"); 557 goto out_free; 558 } 559 560 options = of_find_node_by_path("/options"); 561 err = -ENODEV; 562 if (!options) { 563 pr_err("Unable to find /options node\n"); 564 goto out_iounmap; 565 } 566 567 prop_val = of_get_property(options, "watchdog-enable?", NULL); 568 p->enabled = (prop_val ? true : false); 569 570 prop_val = of_get_property(options, "watchdog-reboot?", NULL); 571 p->reboot = (prop_val ? true : false); 572 573 str_prop = of_get_property(options, "watchdog-timeout", NULL); 574 if (str_prop) 575 p->timeout = simple_strtoul(str_prop, NULL, 10); 576 577 /* CP1400s seem to have broken PLD implementations-- the 578 * interrupt_mask register cannot be written, so no timer 579 * interrupts can be masked within the PLD. 580 */ 581 str_prop = of_get_property(op->dev.of_node, "model", NULL); 582 p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL)); 583 584 if (!p->enabled) 585 cpwd_toggleintr(p, -1, WD_INTR_OFF); 586 587 for (i = 0; i < WD_NUMDEVS; i++) { 588 static const char *cpwd_names[] = { "RIC", "XIR", "POR" }; 589 static int *parms[] = { &wd0_timeout, 590 &wd1_timeout, 591 &wd2_timeout }; 592 struct miscdevice *mp = &p->devs[i].misc; 593 594 mp->minor = WD0_MINOR + i; 595 mp->name = cpwd_names[i]; 596 mp->fops = &cpwd_fops; 597 598 p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ); 599 p->devs[i].intr_mask = (WD0_INTR_MASK << i); 600 p->devs[i].runstatus &= ~WD_STAT_BSTOP; 601 p->devs[i].runstatus |= WD_STAT_INIT; 602 p->devs[i].timeout = p->timeout; 603 if (*parms[i]) 604 p->devs[i].timeout = *parms[i]; 605 606 err = misc_register(&p->devs[i].misc); 607 if (err) { 608 pr_err("Could not register misc device for dev %d\n", 609 i); 610 goto out_unregister; 611 } 612 } 613 614 if (p->broken) { 615 init_timer(&cpwd_timer); 616 cpwd_timer.function = cpwd_brokentimer; 617 cpwd_timer.data = (unsigned long) p; 618 cpwd_timer.expires = WD_BTIMEOUT; 619 620 pr_info("PLD defect workaround enabled for model %s\n", 621 WD_BADMODEL); 622 } 623 624 platform_set_drvdata(op, p); 625 cpwd_device = p; 626 err = 0; 627 628 out: 629 return err; 630 631 out_unregister: 632 for (i--; i >= 0; i--) 633 misc_deregister(&p->devs[i].misc); 634 635 out_iounmap: 636 of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ); 637 638 out_free: 639 kfree(p); 640 goto out; 641 } 642 643 static int cpwd_remove(struct platform_device *op) 644 { 645 struct cpwd *p = platform_get_drvdata(op); 646 int i; 647 648 for (i = 0; i < WD_NUMDEVS; i++) { 649 misc_deregister(&p->devs[i].misc); 650 651 if (!p->enabled) { 652 cpwd_stoptimer(p, i); 653 if (p->devs[i].runstatus & WD_STAT_BSTOP) 654 cpwd_resetbrokentimer(p, i); 655 } 656 } 657 658 if (p->broken) 659 del_timer_sync(&cpwd_timer); 660 661 if (p->initialized) 662 free_irq(p->irq, p); 663 664 of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ); 665 kfree(p); 666 667 cpwd_device = NULL; 668 669 return 0; 670 } 671 672 static const struct of_device_id cpwd_match[] = { 673 { 674 .name = "watchdog", 675 }, 676 {}, 677 }; 678 MODULE_DEVICE_TABLE(of, cpwd_match); 679 680 static struct platform_driver cpwd_driver = { 681 .driver = { 682 .name = DRIVER_NAME, 683 .owner = THIS_MODULE, 684 .of_match_table = cpwd_match, 685 }, 686 .probe = cpwd_probe, 687 .remove = cpwd_remove, 688 }; 689 690 module_platform_driver(cpwd_driver); 691