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[GitHub/LineageOS/android_kernel_samsung_universal7580.git] / drivers / watchdog / cpwd.c
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/init.h>
25 #include <linux/miscdevice.h>
26 #include <linux/interrupt.h>
27 #include <linux/ioport.h>
28 #include <linux/timer.h>
29 #include <linux/slab.h>
30 #include <linux/mutex.h>
31 #include <linux/io.h>
32 #include <linux/of.h>
33 #include <linux/of_device.h>
34 #include <linux/uaccess.h>
35
36 #include <asm/irq.h>
37 #include <asm/watchdog.h>
38
39 #define DRIVER_NAME "cpwd"
40
41 #define WD_OBPNAME "watchdog"
42 #define WD_BADMODEL "SUNW,501-5336"
43 #define WD_BTIMEOUT (jiffies + (HZ * 1000))
44 #define WD_BLIMIT 0xFFFF
45
46 #define WD0_MINOR 212
47 #define WD1_MINOR 213
48 #define WD2_MINOR 214
49
50 /* Internal driver definitions. */
51 #define WD0_ID 0
52 #define WD1_ID 1
53 #define WD2_ID 2
54 #define WD_NUMDEVS 3
55
56 #define WD_INTR_OFF 0
57 #define WD_INTR_ON 1
58
59 #define WD_STAT_INIT 0x01 /* Watchdog timer is initialized */
60 #define WD_STAT_BSTOP 0x02 /* Watchdog timer is brokenstopped */
61 #define WD_STAT_SVCD 0x04 /* Watchdog interrupt occurred */
62
63 /* Register value definitions
64 */
65 #define WD0_INTR_MASK 0x01 /* Watchdog device interrupt masks */
66 #define WD1_INTR_MASK 0x02
67 #define WD2_INTR_MASK 0x04
68
69 #define WD_S_RUNNING 0x01 /* Watchdog device status running */
70 #define WD_S_EXPIRED 0x02 /* Watchdog device status expired */
71
72 struct cpwd {
73 void __iomem *regs;
74 spinlock_t lock;
75
76 unsigned int irq;
77
78 unsigned long timeout;
79 bool enabled;
80 bool reboot;
81 bool broken;
82 bool initialized;
83
84 struct {
85 struct miscdevice misc;
86 void __iomem *regs;
87 u8 intr_mask;
88 u8 runstatus;
89 u16 timeout;
90 } devs[WD_NUMDEVS];
91 };
92
93 static DEFINE_MUTEX(cpwd_mutex);
94 static struct cpwd *cpwd_device;
95
96 /* Sun uses Altera PLD EPF8820ATC144-4
97 * providing three hardware watchdogs:
98 *
99 * 1) RIC - sends an interrupt when triggered
100 * 2) XIR - asserts XIR_B_RESET when triggered, resets CPU
101 * 3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
102 *
103 *** Timer register block definition (struct wd_timer_regblk)
104 *
105 * dcntr and limit registers (halfword access):
106 * -------------------
107 * | 15 | ...| 1 | 0 |
108 * -------------------
109 * |- counter val -|
110 * -------------------
111 * dcntr - Current 16-bit downcounter value.
112 * When downcounter reaches '0' watchdog expires.
113 * Reading this register resets downcounter with
114 * 'limit' value.
115 * limit - 16-bit countdown value in 1/10th second increments.
116 * Writing this register begins countdown with input value.
117 * Reading from this register does not affect counter.
118 * NOTES: After watchdog reset, dcntr and limit contain '1'
119 *
120 * status register (byte access):
121 * ---------------------------
122 * | 7 | ... | 2 | 1 | 0 |
123 * --------------+------------
124 * |- UNUSED -| EXP | RUN |
125 * ---------------------------
126 * status- Bit 0 - Watchdog is running
127 * Bit 1 - Watchdog has expired
128 *
129 *** PLD register block definition (struct wd_pld_regblk)
130 *
131 * intr_mask register (byte access):
132 * ---------------------------------
133 * | 7 | ... | 3 | 2 | 1 | 0 |
134 * +-------------+------------------
135 * |- UNUSED -| WD3 | WD2 | WD1 |
136 * ---------------------------------
137 * WD3 - 1 == Interrupt disabled for watchdog 3
138 * WD2 - 1 == Interrupt disabled for watchdog 2
139 * WD1 - 1 == Interrupt disabled for watchdog 1
140 *
141 * pld_status register (byte access):
142 * UNKNOWN, MAGICAL MYSTERY REGISTER
143 *
144 */
145 #define WD_TIMER_REGSZ 16
146 #define WD0_OFF 0
147 #define WD1_OFF (WD_TIMER_REGSZ * 1)
148 #define WD2_OFF (WD_TIMER_REGSZ * 2)
149 #define PLD_OFF (WD_TIMER_REGSZ * 3)
150
151 #define WD_DCNTR 0x00
152 #define WD_LIMIT 0x04
153 #define WD_STATUS 0x08
154
155 #define PLD_IMASK (PLD_OFF + 0x00)
156 #define PLD_STATUS (PLD_OFF + 0x04)
157
158 static struct timer_list cpwd_timer;
159
160 static int wd0_timeout;
161 static int wd1_timeout;
162 static int wd2_timeout;
163
164 module_param(wd0_timeout, int, 0);
165 MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
166 module_param(wd1_timeout, int, 0);
167 MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
168 module_param(wd2_timeout, int, 0);
169 MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");
170
171 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
172 MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
173 MODULE_LICENSE("GPL");
174 MODULE_SUPPORTED_DEVICE("watchdog");
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(unsigned long data)
235 {
236 struct cpwd *p = (struct cpwd *) data;
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((unsigned long) p);
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 nonseekable_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,
477 unsigned long arg)
478 {
479 int rval = -ENOIOCTLCMD;
480
481 switch (cmd) {
482 /* solaris ioctls are specific to this driver */
483 case WIOCSTART:
484 case WIOCSTOP:
485 case WIOCGSTAT:
486 mutex_lock(&cpwd_mutex);
487 rval = cpwd_ioctl(file, cmd, arg);
488 mutex_unlock(&cpwd_mutex);
489 break;
490
491 /* everything else is handled by the generic compat layer */
492 default:
493 break;
494 }
495
496 return rval;
497 }
498
499 static ssize_t cpwd_write(struct file *file, const char __user *buf,
500 size_t count, loff_t *ppos)
501 {
502 struct inode *inode = file_inode(file);
503 struct cpwd *p = cpwd_device;
504 int index = iminor(inode);
505
506 if (count) {
507 cpwd_pingtimer(p, index);
508 return 1;
509 }
510
511 return 0;
512 }
513
514 static ssize_t cpwd_read(struct file *file, char __user *buffer,
515 size_t count, loff_t *ppos)
516 {
517 return -EINVAL;
518 }
519
520 static const struct file_operations cpwd_fops = {
521 .owner = THIS_MODULE,
522 .unlocked_ioctl = cpwd_ioctl,
523 .compat_ioctl = cpwd_compat_ioctl,
524 .open = cpwd_open,
525 .write = cpwd_write,
526 .read = cpwd_read,
527 .release = cpwd_release,
528 .llseek = no_llseek,
529 };
530
531 static int cpwd_probe(struct platform_device *op)
532 {
533 struct device_node *options;
534 const char *str_prop;
535 const void *prop_val;
536 int i, err = -EINVAL;
537 struct cpwd *p;
538
539 if (cpwd_device)
540 return -EINVAL;
541
542 p = kzalloc(sizeof(*p), GFP_KERNEL);
543 err = -ENOMEM;
544 if (!p) {
545 pr_err("Unable to allocate struct cpwd\n");
546 goto out;
547 }
548
549 p->irq = op->archdata.irqs[0];
550
551 spin_lock_init(&p->lock);
552
553 p->regs = of_ioremap(&op->resource[0], 0,
554 4 * WD_TIMER_REGSZ, DRIVER_NAME);
555 if (!p->regs) {
556 pr_err("Unable to map registers\n");
557 goto out_free;
558 }
559
560 options = of_find_node_by_path("/options");
561 err = -ENODEV;
562 if (!options) {
563 pr_err("Unable to find /options node\n");
564 goto out_iounmap;
565 }
566
567 prop_val = of_get_property(options, "watchdog-enable?", NULL);
568 p->enabled = (prop_val ? true : false);
569
570 prop_val = of_get_property(options, "watchdog-reboot?", NULL);
571 p->reboot = (prop_val ? true : false);
572
573 str_prop = of_get_property(options, "watchdog-timeout", NULL);
574 if (str_prop)
575 p->timeout = simple_strtoul(str_prop, NULL, 10);
576
577 /* CP1400s seem to have broken PLD implementations-- the
578 * interrupt_mask register cannot be written, so no timer
579 * interrupts can be masked within the PLD.
580 */
581 str_prop = of_get_property(op->dev.of_node, "model", NULL);
582 p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));
583
584 if (!p->enabled)
585 cpwd_toggleintr(p, -1, WD_INTR_OFF);
586
587 for (i = 0; i < WD_NUMDEVS; i++) {
588 static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
589 static int *parms[] = { &wd0_timeout,
590 &wd1_timeout,
591 &wd2_timeout };
592 struct miscdevice *mp = &p->devs[i].misc;
593
594 mp->minor = WD0_MINOR + i;
595 mp->name = cpwd_names[i];
596 mp->fops = &cpwd_fops;
597
598 p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
599 p->devs[i].intr_mask = (WD0_INTR_MASK << i);
600 p->devs[i].runstatus &= ~WD_STAT_BSTOP;
601 p->devs[i].runstatus |= WD_STAT_INIT;
602 p->devs[i].timeout = p->timeout;
603 if (*parms[i])
604 p->devs[i].timeout = *parms[i];
605
606 err = misc_register(&p->devs[i].misc);
607 if (err) {
608 pr_err("Could not register misc device for dev %d\n",
609 i);
610 goto out_unregister;
611 }
612 }
613
614 if (p->broken) {
615 init_timer(&cpwd_timer);
616 cpwd_timer.function = cpwd_brokentimer;
617 cpwd_timer.data = (unsigned long) p;
618 cpwd_timer.expires = WD_BTIMEOUT;
619
620 pr_info("PLD defect workaround enabled for model %s\n",
621 WD_BADMODEL);
622 }
623
624 dev_set_drvdata(&op->dev, p);
625 cpwd_device = p;
626 err = 0;
627
628 out:
629 return err;
630
631 out_unregister:
632 for (i--; i >= 0; i--)
633 misc_deregister(&p->devs[i].misc);
634
635 out_iounmap:
636 of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
637
638 out_free:
639 kfree(p);
640 goto out;
641 }
642
643 static int cpwd_remove(struct platform_device *op)
644 {
645 struct cpwd *p = dev_get_drvdata(&op->dev);
646 int i;
647
648 for (i = 0; i < WD_NUMDEVS; i++) {
649 misc_deregister(&p->devs[i].misc);
650
651 if (!p->enabled) {
652 cpwd_stoptimer(p, i);
653 if (p->devs[i].runstatus & WD_STAT_BSTOP)
654 cpwd_resetbrokentimer(p, i);
655 }
656 }
657
658 if (p->broken)
659 del_timer_sync(&cpwd_timer);
660
661 if (p->initialized)
662 free_irq(p->irq, p);
663
664 of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
665 kfree(p);
666
667 cpwd_device = NULL;
668
669 return 0;
670 }
671
672 static const struct of_device_id cpwd_match[] = {
673 {
674 .name = "watchdog",
675 },
676 {},
677 };
678 MODULE_DEVICE_TABLE(of, cpwd_match);
679
680 static struct platform_driver cpwd_driver = {
681 .driver = {
682 .name = DRIVER_NAME,
683 .owner = THIS_MODULE,
684 .of_match_table = cpwd_match,
685 },
686 .probe = cpwd_probe,
687 .remove = cpwd_remove,
688 };
689
690 module_platform_driver(cpwd_driver);