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Linux/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/miscdevice.h>
 25 #include <linux/interrupt.h>
 26 #include <linux/ioport.h>
 27 #include <linux/timer.h>
 28 #include <linux/slab.h>
 29 #include <linux/mutex.h>
 30 #include <linux/io.h>
 31 #include <linux/of.h>
 32 #include <linux/of_device.h>
 33 #include <linux/uaccess.h>
 34 
 35 #include <asm/irq.h>
 36 #include <asm/watchdog.h>
 37 
 38 #define DRIVER_NAME     "cpwd"
 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 '' 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                         pr_err("Cannot register IRQ %d\n", p->irq);
389                         mutex_unlock(&cpwd_mutex);
390                         return -EBUSY;
391                 }
392                 p->initialized = true;
393         }
394 
395         mutex_unlock(&cpwd_mutex);
396 
397         return nonseekable_open(inode, f);
398 }
399 
400 static int cpwd_release(struct inode *inode, struct file *file)
401 {
402         return 0;
403 }
404 
405 static long cpwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
406 {
407         static const struct watchdog_info info = {
408                 .options                = WDIOF_SETTIMEOUT,
409                 .firmware_version       = 1,
410                 .identity               = DRIVER_NAME,
411         };
412         void __user *argp = (void __user *)arg;
413         struct inode *inode = file_inode(file);
414         int index = iminor(inode) - WD0_MINOR;
415         struct cpwd *p = cpwd_device;
416         int setopt = 0;
417 
418         switch (cmd) {
419         /* Generic Linux IOCTLs */
420         case WDIOC_GETSUPPORT:
421                 if (copy_to_user(argp, &info, sizeof(struct watchdog_info)))
422                         return -EFAULT;
423                 break;
424 
425         case WDIOC_GETSTATUS:
426         case WDIOC_GETBOOTSTATUS:
427                 if (put_user(0, (int __user *)argp))
428                         return -EFAULT;
429                 break;
430 
431         case WDIOC_KEEPALIVE:
432                 cpwd_pingtimer(p, index);
433                 break;
434 
435         case WDIOC_SETOPTIONS:
436                 if (copy_from_user(&setopt, argp, sizeof(unsigned int)))
437                         return -EFAULT;
438 
439                 if (setopt & WDIOS_DISABLECARD) {
440                         if (p->enabled)
441                                 return -EINVAL;
442                         cpwd_stoptimer(p, index);
443                 } else if (setopt & WDIOS_ENABLECARD) {
444                         cpwd_starttimer(p, index);
445                 } else {
446                         return -EINVAL;
447                 }
448                 break;
449 
450         /* Solaris-compatible IOCTLs */
451         case WIOCGSTAT:
452                 setopt = cpwd_getstatus(p, index);
453                 if (copy_to_user(argp, &setopt, sizeof(unsigned int)))
454                         return -EFAULT;
455                 break;
456 
457         case WIOCSTART:
458                 cpwd_starttimer(p, index);
459                 break;
460 
461         case WIOCSTOP:
462                 if (p->enabled)
463                         return -EINVAL;
464 
465                 cpwd_stoptimer(p, index);
466                 break;
467 
468         default:
469                 return -EINVAL;
470         }
471 
472         return 0;
473 }
474 
475 static long cpwd_compat_ioctl(struct file *file, unsigned int cmd,
476                               unsigned long arg)
477 {
478         int rval = -ENOIOCTLCMD;
479 
480         switch (cmd) {
481         /* solaris ioctls are specific to this driver */
482         case WIOCSTART:
483         case WIOCSTOP:
484         case WIOCGSTAT:
485                 mutex_lock(&cpwd_mutex);
486                 rval = cpwd_ioctl(file, cmd, arg);
487                 mutex_unlock(&cpwd_mutex);
488                 break;
489 
490         /* everything else is handled by the generic compat layer */
491         default:
492                 break;
493         }
494 
495         return rval;
496 }
497 
498 static ssize_t cpwd_write(struct file *file, const char __user *buf,
499                           size_t count, loff_t *ppos)
500 {
501         struct inode *inode = file_inode(file);
502         struct cpwd *p = cpwd_device;
503         int index = iminor(inode);
504 
505         if (count) {
506                 cpwd_pingtimer(p, index);
507                 return 1;
508         }
509 
510         return 0;
511 }
512 
513 static ssize_t cpwd_read(struct file *file, char __user *buffer,
514                          size_t count, loff_t *ppos)
515 {
516         return -EINVAL;
517 }
518 
519 static const struct file_operations cpwd_fops = {
520         .owner =                THIS_MODULE,
521         .unlocked_ioctl =       cpwd_ioctl,
522         .compat_ioctl =         cpwd_compat_ioctl,
523         .open =                 cpwd_open,
524         .write =                cpwd_write,
525         .read =                 cpwd_read,
526         .release =              cpwd_release,
527         .llseek =               no_llseek,
528 };
529 
530 static int cpwd_probe(struct platform_device *op)
531 {
532         struct device_node *options;
533         const char *str_prop;
534         const void *prop_val;
535         int i, err = -EINVAL;
536         struct cpwd *p;
537 
538         if (cpwd_device)
539                 return -EINVAL;
540 
541         p = kzalloc(sizeof(*p), GFP_KERNEL);
542         err = -ENOMEM;
543         if (!p) {
544                 pr_err("Unable to allocate struct cpwd\n");
545                 goto out;
546         }
547 
548         p->irq = op->archdata.irqs[0];
549 
550         spin_lock_init(&p->lock);
551 
552         p->regs = of_ioremap(&op->resource[0], 0,
553                              4 * WD_TIMER_REGSZ, DRIVER_NAME);
554         if (!p->regs) {
555                 pr_err("Unable to map registers\n");
556                 goto out_free;
557         }
558 
559         options = of_find_node_by_path("/options");
560         err = -ENODEV;
561         if (!options) {
562                 pr_err("Unable to find /options node\n");
563                 goto out_iounmap;
564         }
565 
566         prop_val = of_get_property(options, "watchdog-enable?", NULL);
567         p->enabled = (prop_val ? true : false);
568 
569         prop_val = of_get_property(options, "watchdog-reboot?", NULL);
570         p->reboot = (prop_val ? true : false);
571 
572         str_prop = of_get_property(options, "watchdog-timeout", NULL);
573         if (str_prop)
574                 p->timeout = simple_strtoul(str_prop, NULL, 10);
575 
576         /* CP1400s seem to have broken PLD implementations-- the
577          * interrupt_mask register cannot be written, so no timer
578          * interrupts can be masked within the PLD.
579          */
580         str_prop = of_get_property(op->dev.of_node, "model", NULL);
581         p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));
582 
583         if (!p->enabled)
584                 cpwd_toggleintr(p, -1, WD_INTR_OFF);
585 
586         for (i = 0; i < WD_NUMDEVS; i++) {
587                 static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
588                 static int *parms[] = { &wd0_timeout,
589                                         &wd1_timeout,
590                                         &wd2_timeout };
591                 struct miscdevice *mp = &p->devs[i].misc;
592 
593                 mp->minor = WD0_MINOR + i;
594                 mp->name = cpwd_names[i];
595                 mp->fops = &cpwd_fops;
596 
597                 p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
598                 p->devs[i].intr_mask = (WD0_INTR_MASK << i);
599                 p->devs[i].runstatus &= ~WD_STAT_BSTOP;
600                 p->devs[i].runstatus |= WD_STAT_INIT;
601                 p->devs[i].timeout = p->timeout;
602                 if (*parms[i])
603                         p->devs[i].timeout = *parms[i];
604 
605                 err = misc_register(&p->devs[i].misc);
606                 if (err) {
607                         pr_err("Could not register misc device for dev %d\n",
608                                i);
609                         goto out_unregister;
610                 }
611         }
612 
613         if (p->broken) {
614                 init_timer(&cpwd_timer);
615                 cpwd_timer.function     = cpwd_brokentimer;
616                 cpwd_timer.data         = (unsigned long) p;
617                 cpwd_timer.expires      = WD_BTIMEOUT;
618 
619                 pr_info("PLD defect workaround enabled for model %s\n",
620                         WD_BADMODEL);
621         }
622 
623         platform_set_drvdata(op, p);
624         cpwd_device = p;
625         err = 0;
626 
627 out:
628         return err;
629 
630 out_unregister:
631         for (i--; i >= 0; i--)
632                 misc_deregister(&p->devs[i].misc);
633 
634 out_iounmap:
635         of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
636 
637 out_free:
638         kfree(p);
639         goto out;
640 }
641 
642 static int cpwd_remove(struct platform_device *op)
643 {
644         struct cpwd *p = platform_get_drvdata(op);
645         int i;
646 
647         for (i = 0; i < WD_NUMDEVS; i++) {
648                 misc_deregister(&p->devs[i].misc);
649 
650                 if (!p->enabled) {
651                         cpwd_stoptimer(p, i);
652                         if (p->devs[i].runstatus & WD_STAT_BSTOP)
653                                 cpwd_resetbrokentimer(p, i);
654                 }
655         }
656 
657         if (p->broken)
658                 del_timer_sync(&cpwd_timer);
659 
660         if (p->initialized)
661                 free_irq(p->irq, p);
662 
663         of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
664         kfree(p);
665 
666         cpwd_device = NULL;
667 
668         return 0;
669 }
670 
671 static const struct of_device_id cpwd_match[] = {
672         {
673                 .name = "watchdog",
674         },
675         {},
676 };
677 MODULE_DEVICE_TABLE(of, cpwd_match);
678 
679 static struct platform_driver cpwd_driver = {
680         .driver = {
681                 .name = DRIVER_NAME,
682                 .owner = THIS_MODULE,
683                 .of_match_table = cpwd_match,
684         },
685         .probe          = cpwd_probe,
686         .remove         = cpwd_remove,
687 };
688 
689 module_platform_driver(cpwd_driver);
690 

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