hwmon: (lm75) sensor reading bugfix
[linux-2.6] / drivers / watchdog / hpwdt.c
1 /*
2  *      HP WatchDog Driver
3  *      based on
4  *
5  *      SoftDog 0.05:   A Software Watchdog Device
6  *
7  *      (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
8  *      Thomas Mingarelli <thomas.mingarelli@hp.com>
9  *
10  *      This program is free software; you can redistribute it and/or
11  *      modify it under the terms of the GNU General Public License
12  *      version 2 as published by the Free Software Foundation
13  *
14  */
15
16 #include <linux/device.h>
17 #include <linux/fs.h>
18 #include <linux/init.h>
19 #include <linux/interrupt.h>
20 #include <linux/io.h>
21 #include <linux/irq.h>
22 #include <linux/kernel.h>
23 #include <linux/miscdevice.h>
24 #include <linux/mm.h>
25 #include <linux/module.h>
26 #include <linux/kdebug.h>
27 #include <linux/moduleparam.h>
28 #include <linux/notifier.h>
29 #include <linux/pci.h>
30 #include <linux/pci_ids.h>
31 #include <linux/reboot.h>
32 #include <linux/sched.h>
33 #include <linux/timer.h>
34 #include <linux/types.h>
35 #include <linux/uaccess.h>
36 #include <linux/watchdog.h>
37 #include <linux/dmi.h>
38 #include <linux/efi.h>
39 #include <linux/string.h>
40 #include <linux/bootmem.h>
41 #include <linux/slab.h>
42 #include <asm/dmi.h>
43 #include <asm/desc.h>
44 #include <asm/kdebug.h>
45
46 #define PCI_BIOS32_SD_VALUE             0x5F32335F      /* "_32_" */
47 #define CRU_BIOS_SIGNATURE_VALUE        0x55524324
48 #define PCI_BIOS32_PARAGRAPH_LEN        16
49 #define PCI_ROM_BASE1                   0x000F0000
50 #define ROM_SIZE                        0x10000
51
52 struct bios32_service_dir {
53         u32 signature;
54         u32 entry_point;
55         u8 revision;
56         u8 length;
57         u8 checksum;
58         u8 reserved[5];
59 };
60
61 /* type 212 */
62 struct smbios_cru64_info {
63         u8 type;
64         u8 byte_length;
65         u16 handle;
66         u32 signature;
67         u64 physical_address;
68         u32 double_length;
69         u32 double_offset;
70 };
71 #define SMBIOS_CRU64_INFORMATION        212
72
73 struct cmn_registers {
74         union {
75                 struct {
76                         u8 ral;
77                         u8 rah;
78                         u16 rea2;
79                 };
80                 u32 reax;
81         } u1;
82         union {
83                 struct {
84                         u8 rbl;
85                         u8 rbh;
86                         u8 reb2l;
87                         u8 reb2h;
88                 };
89                 u32 rebx;
90         } u2;
91         union {
92                 struct {
93                         u8 rcl;
94                         u8 rch;
95                         u16 rec2;
96                 };
97                 u32 recx;
98         } u3;
99         union {
100                 struct {
101                         u8 rdl;
102                         u8 rdh;
103                         u16 red2;
104                 };
105                 u32 redx;
106         } u4;
107
108         u32 resi;
109         u32 redi;
110         u16 rds;
111         u16 res;
112         u32 reflags;
113 }  __attribute__((packed));
114
115 #define DEFAULT_MARGIN  30
116 static unsigned int soft_margin = DEFAULT_MARGIN;       /* in seconds */
117 static unsigned int reload;                     /* the computed soft_margin */
118 static int nowayout = WATCHDOG_NOWAYOUT;
119 static char expect_release;
120 static unsigned long hpwdt_is_open;
121
122 static void __iomem *pci_mem_addr;              /* the PCI-memory address */
123 static unsigned long __iomem *hpwdt_timer_reg;
124 static unsigned long __iomem *hpwdt_timer_con;
125
126 static DEFINE_SPINLOCK(rom_lock);
127
128 static void *cru_rom_addr;
129
130 static struct cmn_registers cmn_regs;
131
132 static struct pci_device_id hpwdt_devices[] = {
133         {
134          .vendor = PCI_VENDOR_ID_COMPAQ,
135          .device = 0xB203,
136          .subvendor = PCI_ANY_ID,
137          .subdevice = PCI_ANY_ID,
138         },
139         {0},                    /* terminate list */
140 };
141 MODULE_DEVICE_TABLE(pci, hpwdt_devices);
142
143 #ifndef CONFIG_X86_64
144 /* --32 Bit Bios------------------------------------------------------------ */
145
146 #define HPWDT_ARCH      32
147
148 static void asminline_call(struct cmn_registers *pi86Regs,
149                            unsigned long *pRomEntry)
150 {
151         asm("pushl       %ebp               \n\t"
152             "movl        %esp, %ebp         \n\t"
153             "pusha                          \n\t"
154             "pushf                          \n\t"
155             "push        %es                \n\t"
156             "push        %ds                \n\t"
157             "pop         %es                \n\t"
158             "movl        8(%ebp),%eax       \n\t"
159             "movl        4(%eax),%ebx       \n\t"
160             "movl        8(%eax),%ecx       \n\t"
161             "movl        12(%eax),%edx      \n\t"
162             "movl        16(%eax),%esi      \n\t"
163             "movl        20(%eax),%edi      \n\t"
164             "movl        (%eax),%eax        \n\t"
165             "push        %cs                \n\t"
166             "call        *12(%ebp)          \n\t"
167             "pushf                          \n\t"
168             "pushl       %eax               \n\t"
169             "movl        8(%ebp),%eax       \n\t"
170             "movl        %ebx,4(%eax)       \n\t"
171             "movl        %ecx,8(%eax)       \n\t"
172             "movl        %edx,12(%eax)      \n\t"
173             "movl        %esi,16(%eax)      \n\t"
174             "movl        %edi,20(%eax)      \n\t"
175             "movw        %ds,24(%eax)       \n\t"
176             "movw        %es,26(%eax)       \n\t"
177             "popl        %ebx               \n\t"
178             "movl        %ebx,(%eax)        \n\t"
179             "popl        %ebx               \n\t"
180             "movl        %ebx,28(%eax)      \n\t"
181             "pop         %es                \n\t"
182             "popf                           \n\t"
183             "popa                           \n\t"
184             "leave                          \n\t" "ret");
185 }
186
187 /*
188  *      cru_detect
189  *
190  *      Routine Description:
191  *      This function uses the 32-bit BIOS Service Directory record to
192  *      search for a $CRU record.
193  *
194  *      Return Value:
195  *      0        :  SUCCESS
196  *      <0       :  FAILURE
197  */
198 static int __devinit cru_detect(unsigned long map_entry,
199         unsigned long map_offset)
200 {
201         void *bios32_map;
202         unsigned long *bios32_entrypoint;
203         unsigned long cru_physical_address;
204         unsigned long cru_length;
205         unsigned long physical_bios_base = 0;
206         unsigned long physical_bios_offset = 0;
207         int retval = -ENODEV;
208
209         bios32_map = ioremap(map_entry, (2 * PAGE_SIZE));
210
211         if (bios32_map == NULL)
212                 return -ENODEV;
213
214         bios32_entrypoint = bios32_map + map_offset;
215
216         cmn_regs.u1.reax = CRU_BIOS_SIGNATURE_VALUE;
217
218         asminline_call(&cmn_regs, bios32_entrypoint);
219
220         if (cmn_regs.u1.ral != 0) {
221                 printk(KERN_WARNING
222                        "hpwdt: Call succeeded but with an error: 0x%x\n",
223                        cmn_regs.u1.ral);
224         } else {
225                 physical_bios_base = cmn_regs.u2.rebx;
226                 physical_bios_offset = cmn_regs.u4.redx;
227                 cru_length = cmn_regs.u3.recx;
228                 cru_physical_address =
229                     physical_bios_base + physical_bios_offset;
230
231                 /* If the values look OK, then map it in. */
232                 if ((physical_bios_base + physical_bios_offset)) {
233                         cru_rom_addr =
234                             ioremap(cru_physical_address, cru_length);
235                         if (cru_rom_addr)
236                                 retval = 0;
237                 }
238
239                 printk(KERN_DEBUG "hpwdt: CRU Base Address:   0x%lx\n",
240                         physical_bios_base);
241                 printk(KERN_DEBUG "hpwdt: CRU Offset Address: 0x%lx\n",
242                         physical_bios_offset);
243                 printk(KERN_DEBUG "hpwdt: CRU Length:         0x%lx\n",
244                         cru_length);
245                 printk(KERN_DEBUG "hpwdt: CRU Mapped Address: 0x%x\n",
246                         (unsigned int)&cru_rom_addr);
247         }
248         iounmap(bios32_map);
249         return retval;
250 }
251
252 /*
253  *      bios_checksum
254  */
255 static int __devinit bios_checksum(const char __iomem *ptr, int len)
256 {
257         char sum = 0;
258         int i;
259
260         /*
261          * calculate checksum of size bytes. This should add up
262          * to zero if we have a valid header.
263          */
264         for (i = 0; i < len; i++)
265                 sum += ptr[i];
266
267         return ((sum == 0) && (len > 0));
268 }
269
270 /*
271  *      bios32_present
272  *
273  *      Routine Description:
274  *      This function finds the 32-bit BIOS Service Directory
275  *
276  *      Return Value:
277  *      0        :  SUCCESS
278  *      <0       :  FAILURE
279  */
280 static int __devinit bios32_present(const char __iomem *p)
281 {
282         struct bios32_service_dir *bios_32_ptr;
283         int length;
284         unsigned long map_entry, map_offset;
285
286         bios_32_ptr = (struct bios32_service_dir *) p;
287
288         /*
289          * Search for signature by checking equal to the swizzled value
290          * instead of calling another routine to perform a strcmp.
291          */
292         if (bios_32_ptr->signature == PCI_BIOS32_SD_VALUE) {
293                 length = bios_32_ptr->length * PCI_BIOS32_PARAGRAPH_LEN;
294                 if (bios_checksum(p, length)) {
295                         /*
296                          * According to the spec, we're looking for the
297                          * first 4KB-aligned address below the entrypoint
298                          * listed in the header. The Service Directory code
299                          * is guaranteed to occupy no more than 2 4KB pages.
300                          */
301                         map_entry = bios_32_ptr->entry_point & ~(PAGE_SIZE - 1);
302                         map_offset = bios_32_ptr->entry_point - map_entry;
303
304                         return cru_detect(map_entry, map_offset);
305                 }
306         }
307         return -ENODEV;
308 }
309
310 static int __devinit detect_cru_service(void)
311 {
312         char __iomem *p, *q;
313         int rc = -1;
314
315         /*
316          * Search from 0x0f0000 through 0x0fffff, inclusive.
317          */
318         p = ioremap(PCI_ROM_BASE1, ROM_SIZE);
319         if (p == NULL)
320                 return -ENOMEM;
321
322         for (q = p; q < p + ROM_SIZE; q += 16) {
323                 rc = bios32_present(q);
324                 if (!rc)
325                         break;
326         }
327         iounmap(p);
328         return rc;
329 }
330
331 #else
332 /* --64 Bit Bios------------------------------------------------------------ */
333
334 #define HPWDT_ARCH      64
335
336 static void asminline_call(struct cmn_registers *pi86Regs,
337                            unsigned long *pRomEntry)
338 {
339         asm("pushq      %rbp            \n\t"
340             "movq       %rsp, %rbp      \n\t"
341             "pushq      %rax            \n\t"
342             "pushq      %rbx            \n\t"
343             "pushq      %rdx            \n\t"
344             "pushq      %r12            \n\t"
345             "pushq      %r9             \n\t"
346             "movq       %rsi, %r12      \n\t"
347             "movq       %rdi, %r9       \n\t"
348             "movl       4(%r9),%ebx     \n\t"
349             "movl       8(%r9),%ecx     \n\t"
350             "movl       12(%r9),%edx    \n\t"
351             "movl       16(%r9),%esi    \n\t"
352             "movl       20(%r9),%edi    \n\t"
353             "movl       (%r9),%eax      \n\t"
354             "call       *%r12           \n\t"
355             "pushfq                     \n\t"
356             "popq        %r12           \n\t"
357             "popfq                      \n\t"
358             "movl       %eax, (%r9)     \n\t"
359             "movl       %ebx, 4(%r9)    \n\t"
360             "movl       %ecx, 8(%r9)    \n\t"
361             "movl       %edx, 12(%r9)   \n\t"
362             "movl       %esi, 16(%r9)   \n\t"
363             "movl       %edi, 20(%r9)   \n\t"
364             "movq       %r12, %rax      \n\t"
365             "movl       %eax, 28(%r9)   \n\t"
366             "popq       %r9             \n\t"
367             "popq       %r12            \n\t"
368             "popq       %rdx            \n\t"
369             "popq       %rbx            \n\t"
370             "popq       %rax            \n\t"
371             "leave                      \n\t" "ret");
372 }
373
374 /*
375  *      dmi_find_cru
376  *
377  *      Routine Description:
378  *      This function checks whether or not a SMBIOS/DMI record is
379  *      the 64bit CRU info or not
380  */
381 static void __devinit dmi_find_cru(const struct dmi_header *dm)
382 {
383         struct smbios_cru64_info *smbios_cru64_ptr;
384         unsigned long cru_physical_address;
385
386         if (dm->type == SMBIOS_CRU64_INFORMATION) {
387                 smbios_cru64_ptr = (struct smbios_cru64_info *) dm;
388                 if (smbios_cru64_ptr->signature == CRU_BIOS_SIGNATURE_VALUE) {
389                         cru_physical_address =
390                             smbios_cru64_ptr->physical_address +
391                             smbios_cru64_ptr->double_offset;
392                         cru_rom_addr = ioremap(cru_physical_address,
393                                     smbios_cru64_ptr->double_length);
394                 }
395         }
396 }
397
398 static int __devinit detect_cru_service(void)
399 {
400         cru_rom_addr = NULL;
401
402         dmi_walk(dmi_find_cru);
403
404         /* if cru_rom_addr has been set then we found a CRU service */
405         return ((cru_rom_addr != NULL)? 0: -ENODEV);
406 }
407
408 /* ------------------------------------------------------------------------- */
409
410 #endif
411
412 /*
413  *      NMI Handler
414  */
415 static int hpwdt_pretimeout(struct notifier_block *nb, unsigned long ulReason,
416                             void *data)
417 {
418         static unsigned long rom_pl;
419         static int die_nmi_called;
420
421         if (ulReason == DIE_NMI || ulReason == DIE_NMI_IPI) {
422                 spin_lock_irqsave(&rom_lock, rom_pl);
423                 if (!die_nmi_called)
424                         asminline_call(&cmn_regs, cru_rom_addr);
425                 die_nmi_called = 1;
426                 spin_unlock_irqrestore(&rom_lock, rom_pl);
427                 if (cmn_regs.u1.ral != 0) {
428                         panic("An NMI occurred, please see the Integrated "
429                               "Management Log for details.\n");
430                 }
431         }
432
433         die_nmi_called = 0;
434         return NOTIFY_DONE;
435 }
436
437 /*
438  *      Watchdog operations
439  */
440 static void hpwdt_start(void)
441 {
442         reload = (soft_margin * 1000) / 128;
443         iowrite16(reload, hpwdt_timer_reg);
444         iowrite16(0x85, hpwdt_timer_con);
445 }
446
447 static void hpwdt_stop(void)
448 {
449         unsigned long data;
450
451         data = ioread16(hpwdt_timer_con);
452         data &= 0xFE;
453         iowrite16(data, hpwdt_timer_con);
454 }
455
456 static void hpwdt_ping(void)
457 {
458         iowrite16(reload, hpwdt_timer_reg);
459 }
460
461 static int hpwdt_change_timer(int new_margin)
462 {
463         /* Arbitrary, can't find the card's limits */
464         if (new_margin < 30 || new_margin > 600) {
465                 printk(KERN_WARNING
466                         "hpwdt: New value passed in is invalid: %d seconds.\n",
467                         new_margin);
468                 return -EINVAL;
469         }
470
471         soft_margin = new_margin;
472         printk(KERN_DEBUG
473                 "hpwdt: New timer passed in is %d seconds.\n",
474                 new_margin);
475         reload = (soft_margin * 1000) / 128;
476
477         return 0;
478 }
479
480 /*
481  *      /dev/watchdog handling
482  */
483 static int hpwdt_open(struct inode *inode, struct file *file)
484 {
485         /* /dev/watchdog can only be opened once */
486         if (test_and_set_bit(0, &hpwdt_is_open))
487                 return -EBUSY;
488
489         /* Start the watchdog */
490         hpwdt_start();
491         hpwdt_ping();
492
493         return nonseekable_open(inode, file);
494 }
495
496 static int hpwdt_release(struct inode *inode, struct file *file)
497 {
498         /* Stop the watchdog */
499         if (expect_release == 42) {
500                 hpwdt_stop();
501         } else {
502                 printk(KERN_CRIT
503                         "hpwdt: Unexpected close, not stopping watchdog!\n");
504                 hpwdt_ping();
505         }
506
507         expect_release = 0;
508
509         /* /dev/watchdog is being closed, make sure it can be re-opened */
510         clear_bit(0, &hpwdt_is_open);
511
512         return 0;
513 }
514
515 static ssize_t hpwdt_write(struct file *file, const char __user *data,
516         size_t len, loff_t *ppos)
517 {
518         /* See if we got the magic character 'V' and reload the timer */
519         if (len) {
520                 if (!nowayout) {
521                         size_t i;
522
523                         /* note: just in case someone wrote the magic character
524                          * five months ago... */
525                         expect_release = 0;
526
527                         /* scan to see whether or not we got the magic char. */
528                         for (i = 0; i != len; i++) {
529                                 char c;
530                                 if (get_user(c, data+i))
531                                         return -EFAULT;
532                                 if (c == 'V')
533                                         expect_release = 42;
534                         }
535                 }
536
537                 /* someone wrote to us, we should reload the timer */
538                 hpwdt_ping();
539         }
540
541         return len;
542 }
543
544 static struct watchdog_info ident = {
545         .options = WDIOF_SETTIMEOUT |
546                    WDIOF_KEEPALIVEPING |
547                    WDIOF_MAGICCLOSE,
548         .identity = "HP iLO2 HW Watchdog Timer",
549 };
550
551 static long hpwdt_ioctl(struct file *file, unsigned int cmd,
552         unsigned long arg)
553 {
554         void __user *argp = (void __user *)arg;
555         int __user *p = argp;
556         int new_margin;
557         int ret = -ENOTTY;
558
559         switch (cmd) {
560         case WDIOC_GETSUPPORT:
561                 ret = 0;
562                 if (copy_to_user(argp, &ident, sizeof(ident)))
563                         ret = -EFAULT;
564                 break;
565
566         case WDIOC_GETSTATUS:
567         case WDIOC_GETBOOTSTATUS:
568                 ret = put_user(0, p);
569                 break;
570
571         case WDIOC_KEEPALIVE:
572                 hpwdt_ping();
573                 ret = 0;
574                 break;
575
576         case WDIOC_SETTIMEOUT:
577                 ret = get_user(new_margin, p);
578                 if (ret)
579                         break;
580
581                 ret = hpwdt_change_timer(new_margin);
582                 if (ret)
583                         break;
584
585                 hpwdt_ping();
586                 /* Fall */
587         case WDIOC_GETTIMEOUT:
588                 ret = put_user(soft_margin, p);
589                 break;
590         }
591         return ret;
592 }
593
594 /*
595  *      Kernel interfaces
596  */
597 static struct file_operations hpwdt_fops = {
598         .owner = THIS_MODULE,
599         .llseek = no_llseek,
600         .write = hpwdt_write,
601         .unlocked_ioctl = hpwdt_ioctl,
602         .open = hpwdt_open,
603         .release = hpwdt_release,
604 };
605
606 static struct miscdevice hpwdt_miscdev = {
607         .minor = WATCHDOG_MINOR,
608         .name = "watchdog",
609         .fops = &hpwdt_fops,
610 };
611
612 static struct notifier_block die_notifier = {
613         .notifier_call = hpwdt_pretimeout,
614         .priority = 0x7FFFFFFF,
615 };
616
617 /*
618  *      Init & Exit
619  */
620
621 static int __devinit hpwdt_init_one(struct pci_dev *dev,
622                                     const struct pci_device_id *ent)
623 {
624         int retval;
625
626         /*
627          * First let's find out if we are on an iLO2 server. We will
628          * not run on a legacy ASM box.
629          */
630         if (dev->subsystem_vendor != PCI_VENDOR_ID_HP) {
631                 dev_warn(&dev->dev,
632                        "This server does not have an iLO2 ASIC.\n");
633                 return -ENODEV;
634         }
635
636         if (pci_enable_device(dev)) {
637                 dev_warn(&dev->dev,
638                         "Not possible to enable PCI Device: 0x%x:0x%x.\n",
639                         ent->vendor, ent->device);
640                 return -ENODEV;
641         }
642
643         pci_mem_addr = pci_iomap(dev, 1, 0x80);
644         if (!pci_mem_addr) {
645                 dev_warn(&dev->dev,
646                         "Unable to detect the iLO2 server memory.\n");
647                 retval = -ENOMEM;
648                 goto error_pci_iomap;
649         }
650         hpwdt_timer_reg = pci_mem_addr + 0x70;
651         hpwdt_timer_con = pci_mem_addr + 0x72;
652
653         /* Make sure that we have a valid soft_margin */
654         if (hpwdt_change_timer(soft_margin))
655                 hpwdt_change_timer(DEFAULT_MARGIN);
656
657         /*
658          * We need to map the ROM to get the CRU service.
659          * For 32 bit Operating Systems we need to go through the 32 Bit
660          * BIOS Service Directory
661          * For 64 bit Operating Systems we get that service through SMBIOS.
662          */
663         retval = detect_cru_service();
664         if (retval < 0) {
665                 dev_warn(&dev->dev,
666                        "Unable to detect the %d Bit CRU Service.\n",
667                         HPWDT_ARCH);
668                 goto error_get_cru;
669         }
670
671         /*
672          * We know this is the only CRU call we need to make so lets keep as
673          * few instructions as possible once the NMI comes in.
674          */
675         cmn_regs.u1.rah = 0x0D;
676         cmn_regs.u1.ral = 0x02;
677
678         retval = register_die_notifier(&die_notifier);
679         if (retval != 0) {
680                 dev_warn(&dev->dev,
681                        "Unable to register a die notifier (err=%d).\n",
682                         retval);
683                 goto error_die_notifier;
684         }
685
686         retval = misc_register(&hpwdt_miscdev);
687         if (retval < 0) {
688                 dev_warn(&dev->dev,
689                         "Unable to register miscdev on minor=%d (err=%d).\n",
690                         WATCHDOG_MINOR, retval);
691                 goto error_misc_register;
692         }
693
694         printk(KERN_INFO
695                 "hp Watchdog Timer Driver: 1.00"
696                 ", timer margin: %d seconds( nowayout=%d).\n",
697                 soft_margin, nowayout);
698
699         return 0;
700
701 error_misc_register:
702         unregister_die_notifier(&die_notifier);
703 error_die_notifier:
704         if (cru_rom_addr)
705                 iounmap(cru_rom_addr);
706 error_get_cru:
707         pci_iounmap(dev, pci_mem_addr);
708 error_pci_iomap:
709         pci_disable_device(dev);
710         return retval;
711 }
712
713 static void __devexit hpwdt_exit(struct pci_dev *dev)
714 {
715         if (!nowayout)
716                 hpwdt_stop();
717
718         misc_deregister(&hpwdt_miscdev);
719         unregister_die_notifier(&die_notifier);
720
721         if (cru_rom_addr)
722                 iounmap(cru_rom_addr);
723         pci_iounmap(dev, pci_mem_addr);
724         pci_disable_device(dev);
725 }
726
727 static struct pci_driver hpwdt_driver = {
728         .name = "hpwdt",
729         .id_table = hpwdt_devices,
730         .probe = hpwdt_init_one,
731         .remove = __devexit_p(hpwdt_exit),
732 };
733
734 static void __exit hpwdt_cleanup(void)
735 {
736         pci_unregister_driver(&hpwdt_driver);
737 }
738
739 static int __init hpwdt_init(void)
740 {
741         return pci_register_driver(&hpwdt_driver);
742 }
743
744 MODULE_AUTHOR("Tom Mingarelli");
745 MODULE_DESCRIPTION("hp watchdog driver");
746 MODULE_LICENSE("GPL");
747 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
748
749 module_param(soft_margin, int, 0);
750 MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
751
752 module_param(nowayout, int, 0);
753 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
754                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
755
756 module_init(hpwdt_init);
757 module_exit(hpwdt_cleanup);