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/platform_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
cpwd_writew(u16 val,void __iomem * addr)176 static void cpwd_writew(u16 val, void __iomem *addr)
177 {
178 writew(cpu_to_le16(val), addr);
179 }
cpwd_readw(void __iomem * addr)180 static u16 cpwd_readw(void __iomem *addr)
181 {
182 u16 val = readw(addr);
183
184 return le16_to_cpu(val);
185 }
186
cpwd_writeb(u8 val,void __iomem * addr)187 static void cpwd_writeb(u8 val, void __iomem *addr)
188 {
189 writeb(val, addr);
190 }
191
cpwd_readb(void __iomem * addr)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 */
cpwd_toggleintr(struct cpwd * p,int index,int enable)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 */
cpwd_resetbrokentimer(struct cpwd * p,int index)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 */
cpwd_brokentimer(struct timer_list * unused)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 */
cpwd_pingtimer(struct cpwd * p,int index)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 */
cpwd_stoptimer(struct cpwd * p,int index)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 */
cpwd_starttimer(struct cpwd * p,int index)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
cpwd_getstatus(struct cpwd * p,int index)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
cpwd_interrupt(int irq,void * dev_id)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
cpwd_open(struct inode * inode,struct file * f)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
cpwd_release(struct inode * inode,struct file * file)401 static int cpwd_release(struct inode *inode, struct file *file)
402 {
403 return 0;
404 }
405
cpwd_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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
cpwd_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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
cpwd_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)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
cpwd_read(struct file * file,char __user * buffer,size_t count,loff_t * ppos)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
cpwd_probe(struct platform_device * op)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
cpwd_remove(struct platform_device * op)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