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[linux-2.6.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 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/fs.h>
20 #include <linux/errno.h>
21 #include <linux/major.h>
22 #include <linux/init.h>
23 #include <linux/miscdevice.h>
24 #include <linux/interrupt.h>
25 #include <linux/ioport.h>
26 #include <linux/timer.h>
27 #include <linux/slab.h>
28 #include <linux/mutex.h>
29 #include <linux/io.h>
30 #include <linux/of.h>
31 #include <linux/of_device.h>
32 #include <linux/uaccess.h>
33
34 #include <asm/irq.h>
35 #include <asm/watchdog.h>
36
37 #define DRIVER_NAME     "cpwd"
38 #define PFX             DRIVER_NAME ": "
39
40 #define WD_OBPNAME      "watchdog"
41 #define WD_BADMODEL     "SUNW,501-5336"
42 #define WD_BTIMEOUT     (jiffies + (HZ * 1000))
43 #define WD_BLIMIT       0xFFFF
44
45 #define WD0_MINOR       212
46 #define WD1_MINOR       213
47 #define WD2_MINOR       214
48
49 /* Internal driver definitions.  */
50 #define WD0_ID                  0
51 #define WD1_ID                  1
52 #define WD2_ID                  2
53 #define WD_NUMDEVS              3
54
55 #define WD_INTR_OFF             0
56 #define WD_INTR_ON              1
57
58 #define WD_STAT_INIT    0x01    /* Watchdog timer is initialized        */
59 #define WD_STAT_BSTOP   0x02    /* Watchdog timer is brokenstopped      */
60 #define WD_STAT_SVCD    0x04    /* Watchdog interrupt occurred          */
61
62 /* Register value definitions
63  */
64 #define WD0_INTR_MASK   0x01    /* Watchdog device interrupt masks      */
65 #define WD1_INTR_MASK   0x02
66 #define WD2_INTR_MASK   0x04
67
68 #define WD_S_RUNNING    0x01    /* Watchdog device status running       */
69 #define WD_S_EXPIRED    0x02    /* Watchdog device status expired       */
70
71 struct cpwd {
72         void __iomem    *regs;
73         spinlock_t      lock;
74
75         unsigned int    irq;
76
77         unsigned long   timeout;
78         bool            enabled;
79         bool            reboot;
80         bool            broken;
81         bool            initialized;
82
83         struct {
84                 struct miscdevice       misc;
85                 void __iomem            *regs;
86                 u8                      intr_mask;
87                 u8                      runstatus;
88                 u16                     timeout;
89         } devs[WD_NUMDEVS];
90 };
91
92 static DEFINE_MUTEX(cpwd_mutex);
93 static struct cpwd *cpwd_device;
94
95 /* Sun uses Altera PLD EPF8820ATC144-4
96  * providing three hardware watchdogs:
97  *
98  * 1) RIC - sends an interrupt when triggered
99  * 2) XIR - asserts XIR_B_RESET when triggered, resets CPU
100  * 3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
101  *
102  *** Timer register block definition (struct wd_timer_regblk)
103  *
104  * dcntr and limit registers (halfword access):
105  * -------------------
106  * | 15 | ...| 1 | 0 |
107  * -------------------
108  * |-  counter val  -|
109  * -------------------
110  * dcntr -      Current 16-bit downcounter value.
111  *                      When downcounter reaches '0' watchdog expires.
112  *                      Reading this register resets downcounter with
113  *                      'limit' value.
114  * limit -      16-bit countdown value in 1/10th second increments.
115  *                      Writing this register begins countdown with input value.
116  *                      Reading from this register does not affect counter.
117  * NOTES:       After watchdog reset, dcntr and limit contain '1'
118  *
119  * status register (byte access):
120  * ---------------------------
121  * | 7 | ... | 2 |  1  |  0  |
122  * --------------+------------
123  * |-   UNUSED  -| EXP | RUN |
124  * ---------------------------
125  * status-      Bit 0 - Watchdog is running
126  *                      Bit 1 - Watchdog has expired
127  *
128  *** PLD register block definition (struct wd_pld_regblk)
129  *
130  * intr_mask register (byte access):
131  * ---------------------------------
132  * | 7 | ... | 3 |  2  |  1  |  0  |
133  * +-------------+------------------
134  * |-   UNUSED  -| WD3 | WD2 | WD1 |
135  * ---------------------------------
136  * WD3 -  1 == Interrupt disabled for watchdog 3
137  * WD2 -  1 == Interrupt disabled for watchdog 2
138  * WD1 -  1 == Interrupt disabled for watchdog 1
139  *
140  * pld_status register (byte access):
141  * UNKNOWN, MAGICAL MYSTERY REGISTER
142  *
143  */
144 #define WD_TIMER_REGSZ  16
145 #define WD0_OFF         0
146 #define WD1_OFF         (WD_TIMER_REGSZ * 1)
147 #define WD2_OFF         (WD_TIMER_REGSZ * 2)
148 #define PLD_OFF         (WD_TIMER_REGSZ * 3)
149
150 #define WD_DCNTR        0x00
151 #define WD_LIMIT        0x04
152 #define WD_STATUS       0x08
153
154 #define PLD_IMASK       (PLD_OFF + 0x00)
155 #define PLD_STATUS      (PLD_OFF + 0x04)
156
157 static struct timer_list cpwd_timer;
158
159 static int wd0_timeout;
160 static int wd1_timeout;
161 static int wd2_timeout;
162
163 module_param(wd0_timeout, int, 0);
164 MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
165 module_param(wd1_timeout, int, 0);
166 MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
167 module_param(wd2_timeout, int, 0);
168 MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");
169
170 MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
171 MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
172 MODULE_LICENSE("GPL");
173 MODULE_SUPPORTED_DEVICE("watchdog");
174
175 static void cpwd_writew(u16 val, void __iomem *addr)
176 {
177         writew(cpu_to_le16(val), addr);
178 }
179 static u16 cpwd_readw(void __iomem *addr)
180 {
181         u16 val = readw(addr);
182
183         return le16_to_cpu(val);
184 }
185
186 static void cpwd_writeb(u8 val, void __iomem *addr)
187 {
188         writeb(val, addr);
189 }
190
191 static u8 cpwd_readb(void __iomem *addr)
192 {
193         return readb(addr);
194 }
195
196 /* Enable or disable watchdog interrupts
197  * Because of the CP1400 defect this should only be
198  * called during initialzation or by wd_[start|stop]timer()
199  *
200  * index        - sub-device index, or -1 for 'all'
201  * enable       - non-zero to enable interrupts, zero to disable
202  */
203 static void cpwd_toggleintr(struct cpwd *p, int index, int enable)
204 {
205         unsigned char curregs = cpwd_readb(p->regs + PLD_IMASK);
206         unsigned char setregs =
207                 (index == -1) ?
208                 (WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) :
209                 (p->devs[index].intr_mask);
210
211         if (enable == WD_INTR_ON)
212                 curregs &= ~setregs;
213         else
214                 curregs |= setregs;
215
216         cpwd_writeb(curregs, p->regs + PLD_IMASK);
217 }
218
219 /* Restarts timer with maximum limit value and
220  * does not unset 'brokenstop' value.
221  */
222 static void cpwd_resetbrokentimer(struct cpwd *p, int index)
223 {
224         cpwd_toggleintr(p, index, WD_INTR_ON);
225         cpwd_writew(WD_BLIMIT, p->devs[index].regs + WD_LIMIT);
226 }
227
228 /* Timer method called to reset stopped watchdogs--
229  * because of the PLD bug on CP1400, we cannot mask
230  * interrupts within the PLD so me must continually
231  * reset the timers ad infinitum.
232  */
233 static void cpwd_brokentimer(unsigned long data)
234 {
235         struct cpwd *p = (struct cpwd *) data;
236         int id, tripped = 0;
237
238         /* kill a running timer instance, in case we
239          * were called directly instead of by kernel timer
240          */
241         if (timer_pending(&cpwd_timer))
242                 del_timer(&cpwd_timer);
243
244         for (id = 0; id < WD_NUMDEVS; id++) {
245                 if (p->devs[id].runstatus & WD_STAT_BSTOP) {
246                         ++tripped;
247                         cpwd_resetbrokentimer(p, id);
248                 }
249         }
250
251         if (tripped) {
252                 /* there is at least one timer brokenstopped-- reschedule */
253                 cpwd_timer.expires = WD_BTIMEOUT;
254                 add_timer(&cpwd_timer);
255         }
256 }
257
258 /* Reset countdown timer with 'limit' value and continue countdown.
259  * This will not start a stopped timer.
260  */
261 static void cpwd_pingtimer(struct cpwd *p, int index)
262 {
263         if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING)
264                 cpwd_readw(p->devs[index].regs + WD_DCNTR);
265 }
266
267 /* Stop a running watchdog timer-- the timer actually keeps
268  * running, but the interrupt is masked so that no action is
269  * taken upon expiration.
270  */
271 static void cpwd_stoptimer(struct cpwd *p, int index)
272 {
273         if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING) {
274                 cpwd_toggleintr(p, index, WD_INTR_OFF);
275
276                 if (p->broken) {
277                         p->devs[index].runstatus |= WD_STAT_BSTOP;
278                         cpwd_brokentimer((unsigned long) p);
279                 }
280         }
281 }
282
283 /* Start a watchdog timer with the specified limit value
284  * If the watchdog is running, it will be restarted with
285  * the provided limit value.
286  *
287  * This function will enable interrupts on the specified
288  * watchdog.
289  */
290 static void cpwd_starttimer(struct cpwd *p, int index)
291 {
292         if (p->broken)
293                 p->devs[index].runstatus &= ~WD_STAT_BSTOP;
294
295         p->devs[index].runstatus &= ~WD_STAT_SVCD;
296
297         cpwd_writew(p->devs[index].timeout, p->devs[index].regs + WD_LIMIT);
298         cpwd_toggleintr(p, index, WD_INTR_ON);
299 }
300
301 static int cpwd_getstatus(struct cpwd *p, int index)
302 {
303         unsigned char stat = cpwd_readb(p->devs[index].regs + WD_STATUS);
304         unsigned char intr = cpwd_readb(p->devs[index].regs + PLD_IMASK);
305         unsigned char ret  = WD_STOPPED;
306
307         /* determine STOPPED */
308         if (!stat)
309                 return ret;
310
311         /* determine EXPIRED vs FREERUN vs RUNNING */
312         else if (WD_S_EXPIRED & stat) {
313                 ret = WD_EXPIRED;
314         } else if (WD_S_RUNNING & stat) {
315                 if (intr & p->devs[index].intr_mask) {
316                         ret = WD_FREERUN;
317                 } else {
318                         /* Fudge WD_EXPIRED status for defective CP1400--
319                          * IF timer is running
320                          *      AND brokenstop is set
321                          *      AND an interrupt has been serviced
322                          * we are WD_EXPIRED.
323                          *
324                          * IF timer is running
325                          *      AND brokenstop is set
326                          *      AND no interrupt has been serviced
327                          * we are WD_FREERUN.
328                          */
329                         if (p->broken &&
330                             (p->devs[index].runstatus & WD_STAT_BSTOP)) {
331                                 if (p->devs[index].runstatus & WD_STAT_SVCD) {
332                                         ret = WD_EXPIRED;
333                                 } else {
334                                         /* we could as well pretend
335                                          * we are expired */
336                                         ret = WD_FREERUN;
337                                 }
338                         } else {
339                                 ret = WD_RUNNING;
340                         }
341                 }
342         }
343
344         /* determine SERVICED */
345         if (p->devs[index].runstatus & WD_STAT_SVCD)
346                 ret |= WD_SERVICED;
347
348         return ret;
349 }
350
351 static irqreturn_t cpwd_interrupt(int irq, void *dev_id)
352 {
353         struct cpwd *p = dev_id;
354
355         /* Only WD0 will interrupt-- others are NMI and we won't
356          * see them here....
357          */
358         spin_lock_irq(&p->lock);
359
360         cpwd_stoptimer(p, WD0_ID);
361         p->devs[WD0_ID].runstatus |=  WD_STAT_SVCD;
362
363         spin_unlock_irq(&p->lock);
364
365         return IRQ_HANDLED;
366 }
367
368 static int cpwd_open(struct inode *inode, struct file *f)
369 {
370         struct cpwd *p = cpwd_device;
371
372         mutex_lock(&cpwd_mutex);
373         switch (iminor(inode)) {
374         case WD0_MINOR:
375         case WD1_MINOR:
376         case WD2_MINOR:
377                 break;
378
379         default:
380                 mutex_unlock(&cpwd_mutex);
381                 return -ENODEV;
382         }
383
384         /* Register IRQ on first open of device */
385         if (!p->initialized) {
386                 if (request_irq(p->irq, &cpwd_interrupt,
387                                 IRQF_SHARED, DRIVER_NAME, p)) {
388                         printk(KERN_ERR PFX "Cannot register IRQ %d\n",
389                                 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->f_path.dentry->d_inode;
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->f_path.dentry->d_inode;
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 __devinit 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                 printk(KERN_ERR PFX "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                 printk(KERN_ERR PFX "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                 printk(KERN_ERR PFX "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                         printk(KERN_ERR "Could not register misc device for "
609                                "dev %d\n", 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                 printk(KERN_INFO PFX "PLD defect workaround enabled for "
621                        "model " WD_BADMODEL ".\n");
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 __devexit 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         = __devexit_p(cpwd_remove),
688 };
689
690 static int __init cpwd_init(void)
691 {
692         return platform_driver_register(&cpwd_driver);
693 }
694
695 static void __exit cpwd_exit(void)
696 {
697         platform_driver_unregister(&cpwd_driver);
698 }
699
700 module_init(cpwd_init);
701 module_exit(cpwd_exit);