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
cpwd_writew(u16 val,void __iomem * addr)177 static void cpwd_writew(u16 val, void __iomem *addr)
178 {
179 writew(cpu_to_le16(val), addr);
180 }
cpwd_readw(void __iomem * addr)181 static u16 cpwd_readw(void __iomem *addr)
182 {
183 u16 val = readw(addr);
184
185 return le16_to_cpu(val);
186 }
187
cpwd_writeb(u8 val,void __iomem * addr)188 static void cpwd_writeb(u8 val, void __iomem *addr)
189 {
190 writeb(val, addr);
191 }
192
cpwd_readb(void __iomem * addr)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 */
cpwd_toggleintr(struct cpwd * p,int index,int enable)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 */
cpwd_resetbrokentimer(struct cpwd * p,int index)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 */
cpwd_brokentimer(struct timer_list * unused)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 */
cpwd_pingtimer(struct cpwd * p,int index)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 */
cpwd_stoptimer(struct cpwd * p,int index)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 */
cpwd_starttimer(struct cpwd * p,int index)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
cpwd_getstatus(struct cpwd * p,int index)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
cpwd_interrupt(int irq,void * dev_id)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
cpwd_open(struct inode * inode,struct file * f)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
cpwd_release(struct inode * inode,struct file * file)402 static int cpwd_release(struct inode *inode, struct file *file)
403 {
404 return 0;
405 }
406
cpwd_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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
cpwd_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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
cpwd_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)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
cpwd_read(struct file * file,char __user * buffer,size_t count,loff_t * ppos)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
cpwd_probe(struct platform_device * op)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
cpwd_remove(struct platform_device * op)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