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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/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 '' 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         platform_set_drvdata(op, 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 = platform_get_drvdata(op);
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);
691 

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