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