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"); 175 176 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 long cpwd_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 477 { 478 return cpwd_ioctl(file, cmd, (unsigned long)compat_ptr(arg)); 479 } 480 481 static ssize_t cpwd_write(struct file *file, const char __user *buf, 482 size_t count, loff_t *ppos) 483 { 484 struct inode *inode = file_inode(file); 485 struct cpwd *p = cpwd_device; 486 int index = iminor(inode); 487 488 if (count) { 489 cpwd_pingtimer(p, index); 490 return 1; 491 } 492 493 return 0; 494 } 495 496 static ssize_t cpwd_read(struct file *file, char __user *buffer, 497 size_t count, loff_t *ppos) 498 { 499 return -EINVAL; 500 } 501 502 static const struct file_operations cpwd_fops = { 503 .owner = THIS_MODULE, 504 .unlocked_ioctl = cpwd_ioctl, 505 .compat_ioctl = cpwd_compat_ioctl, 506 .open = cpwd_open, 507 .write = cpwd_write, 508 .read = cpwd_read, 509 .release = cpwd_release, 510 .llseek = no_llseek, 511 }; 512 513 static int cpwd_probe(struct platform_device *op) 514 { 515 struct device_node *options; 516 const char *str_prop; 517 const void *prop_val; 518 int i, err = -EINVAL; 519 struct cpwd *p; 520 521 if (cpwd_device) 522 return -EINVAL; 523 524 p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL); 525 if (!p) 526 return -ENOMEM; 527 528 p->irq = op->archdata.irqs[0]; 529 530 spin_lock_init(&p->lock); 531 532 p->regs = of_ioremap(&op->resource[0], 0, 533 4 * WD_TIMER_REGSZ, DRIVER_NAME); 534 if (!p->regs) { 535 pr_err("Unable to map registers\n"); 536 return -ENOMEM; 537 } 538 539 options = of_find_node_by_path("/options"); 540 if (!options) { 541 err = -ENODEV; 542 pr_err("Unable to find /options node\n"); 543 goto out_iounmap; 544 } 545 546 prop_val = of_get_property(options, "watchdog-enable?", NULL); 547 p->enabled = (prop_val ? true : false); 548 549 prop_val = of_get_property(options, "watchdog-reboot?", NULL); 550 p->reboot = (prop_val ? true : false); 551 552 str_prop = of_get_property(options, "watchdog-timeout", NULL); 553 if (str_prop) 554 p->timeout = simple_strtoul(str_prop, NULL, 10); 555 556 of_node_put(options); 557 558 /* CP1400s seem to have broken PLD implementations-- the 559 * interrupt_mask register cannot be written, so no timer 560 * interrupts can be masked within the PLD. 561 */ 562 str_prop = of_get_property(op->dev.of_node, "model", NULL); 563 p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL)); 564 565 if (!p->enabled) 566 cpwd_toggleintr(p, -1, WD_INTR_OFF); 567 568 for (i = 0; i < WD_NUMDEVS; i++) { 569 static const char *cpwd_names[] = { "RIC", "XIR", "POR" }; 570 static int *parms[] = { &wd0_timeout, 571 &wd1_timeout, 572 &wd2_timeout }; 573 struct miscdevice *mp = &p->devs[i].misc; 574 575 mp->minor = WD0_MINOR + i; 576 mp->name = cpwd_names[i]; 577 mp->fops = &cpwd_fops; 578 579 p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ); 580 p->devs[i].intr_mask = (WD0_INTR_MASK << i); 581 p->devs[i].runstatus &= ~WD_STAT_BSTOP; 582 p->devs[i].runstatus |= WD_STAT_INIT; 583 p->devs[i].timeout = p->timeout; 584 if (*parms[i]) 585 p->devs[i].timeout = *parms[i]; 586 587 err = misc_register(&p->devs[i].misc); 588 if (err) { 589 pr_err("Could not register misc device for dev %d\n", 590 i); 591 goto out_unregister; 592 } 593 } 594 595 if (p->broken) { 596 timer_setup(&cpwd_timer, cpwd_brokentimer, 0); 597 cpwd_timer.expires = WD_BTIMEOUT; 598 599 pr_info("PLD defect workaround enabled for model %s\n", 600 WD_BADMODEL); 601 } 602 603 platform_set_drvdata(op, p); 604 cpwd_device = p; 605 return 0; 606 607 out_unregister: 608 for (i--; i >= 0; i--) 609 misc_deregister(&p->devs[i].misc); 610 611 out_iounmap: 612 of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ); 613 614 return err; 615 } 616 617 static void cpwd_remove(struct platform_device *op) 618 { 619 struct cpwd *p = platform_get_drvdata(op); 620 int i; 621 622 for (i = 0; i < WD_NUMDEVS; i++) { 623 misc_deregister(&p->devs[i].misc); 624 625 if (!p->enabled) { 626 cpwd_stoptimer(p, i); 627 if (p->devs[i].runstatus & WD_STAT_BSTOP) 628 cpwd_resetbrokentimer(p, i); 629 } 630 } 631 632 if (p->broken) 633 del_timer_sync(&cpwd_timer); 634 635 if (p->initialized) 636 free_irq(p->irq, p); 637 638 of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ); 639 640 cpwd_device = NULL; 641 } 642 643 static const struct of_device_id cpwd_match[] = { 644 { 645 .name = "watchdog", 646 }, 647 {}, 648 }; 649 MODULE_DEVICE_TABLE(of, cpwd_match); 650 651 static struct platform_driver cpwd_driver = { 652 .driver = { 653 .name = DRIVER_NAME, 654 .of_match_table = cpwd_match, 655 }, 656 .probe = cpwd_probe, 657 .remove_new = cpwd_remove, 658 }; 659 660 module_platform_driver(cpwd_driver); 661