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); 664