PM / Hibernate: Update some comments in core hibernate code
[linux-2.6.git] / kernel / power / hibernate.c
1 /*
2  * kernel/power/hibernate.c - Hibernation (a.k.a suspend-to-disk) support.
3  *
4  * Copyright (c) 2003 Patrick Mochel
5  * Copyright (c) 2003 Open Source Development Lab
6  * Copyright (c) 2004 Pavel Machek <pavel@ucw.cz>
7  * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
8  *
9  * This file is released under the GPLv2.
10  */
11
12 #include <linux/suspend.h>
13 #include <linux/syscalls.h>
14 #include <linux/reboot.h>
15 #include <linux/string.h>
16 #include <linux/device.h>
17 #include <linux/kmod.h>
18 #include <linux/delay.h>
19 #include <linux/fs.h>
20 #include <linux/mount.h>
21 #include <linux/pm.h>
22 #include <linux/console.h>
23 #include <linux/cpu.h>
24 #include <linux/freezer.h>
25 #include <linux/gfp.h>
26 #include <linux/syscore_ops.h>
27 #include <scsi/scsi_scan.h>
28 #include <asm/suspend.h>
29
30 #include "power.h"
31
32
33 static int nocompress = 0;
34 static int noresume = 0;
35 static char resume_file[256] = CONFIG_PM_STD_PARTITION;
36 dev_t swsusp_resume_device;
37 sector_t swsusp_resume_block;
38 int in_suspend __nosavedata = 0;
39
40 enum {
41         HIBERNATION_INVALID,
42         HIBERNATION_PLATFORM,
43         HIBERNATION_TEST,
44         HIBERNATION_TESTPROC,
45         HIBERNATION_SHUTDOWN,
46         HIBERNATION_REBOOT,
47         /* keep last */
48         __HIBERNATION_AFTER_LAST
49 };
50 #define HIBERNATION_MAX (__HIBERNATION_AFTER_LAST-1)
51 #define HIBERNATION_FIRST (HIBERNATION_INVALID + 1)
52
53 static int hibernation_mode = HIBERNATION_SHUTDOWN;
54
55 static const struct platform_hibernation_ops *hibernation_ops;
56
57 /**
58  * hibernation_set_ops - set the global hibernate operations
59  * @ops: the hibernation operations to use in subsequent hibernation transitions
60  */
61
62 void hibernation_set_ops(const struct platform_hibernation_ops *ops)
63 {
64         if (ops && !(ops->begin && ops->end &&  ops->pre_snapshot
65             && ops->prepare && ops->finish && ops->enter && ops->pre_restore
66             && ops->restore_cleanup && ops->leave)) {
67                 WARN_ON(1);
68                 return;
69         }
70         mutex_lock(&pm_mutex);
71         hibernation_ops = ops;
72         if (ops)
73                 hibernation_mode = HIBERNATION_PLATFORM;
74         else if (hibernation_mode == HIBERNATION_PLATFORM)
75                 hibernation_mode = HIBERNATION_SHUTDOWN;
76
77         mutex_unlock(&pm_mutex);
78 }
79
80 static bool entering_platform_hibernation;
81
82 bool system_entering_hibernation(void)
83 {
84         return entering_platform_hibernation;
85 }
86 EXPORT_SYMBOL(system_entering_hibernation);
87
88 #ifdef CONFIG_PM_DEBUG
89 static void hibernation_debug_sleep(void)
90 {
91         printk(KERN_INFO "hibernation debug: Waiting for 5 seconds.\n");
92         mdelay(5000);
93 }
94
95 static int hibernation_testmode(int mode)
96 {
97         if (hibernation_mode == mode) {
98                 hibernation_debug_sleep();
99                 return 1;
100         }
101         return 0;
102 }
103
104 static int hibernation_test(int level)
105 {
106         if (pm_test_level == level) {
107                 hibernation_debug_sleep();
108                 return 1;
109         }
110         return 0;
111 }
112 #else /* !CONFIG_PM_DEBUG */
113 static int hibernation_testmode(int mode) { return 0; }
114 static int hibernation_test(int level) { return 0; }
115 #endif /* !CONFIG_PM_DEBUG */
116
117 /**
118  *      platform_begin - tell the platform driver that we're starting
119  *      hibernation
120  */
121
122 static int platform_begin(int platform_mode)
123 {
124         return (platform_mode && hibernation_ops) ?
125                 hibernation_ops->begin() : 0;
126 }
127
128 /**
129  *      platform_end - tell the platform driver that we've entered the
130  *      working state
131  */
132
133 static void platform_end(int platform_mode)
134 {
135         if (platform_mode && hibernation_ops)
136                 hibernation_ops->end();
137 }
138
139 /**
140  *      platform_pre_snapshot - prepare the machine for hibernation using the
141  *      platform driver if so configured and return an error code if it fails
142  */
143
144 static int platform_pre_snapshot(int platform_mode)
145 {
146         return (platform_mode && hibernation_ops) ?
147                 hibernation_ops->pre_snapshot() : 0;
148 }
149
150 /**
151  *      platform_leave - prepare the machine for switching to the normal mode
152  *      of operation using the platform driver (called with interrupts disabled)
153  */
154
155 static void platform_leave(int platform_mode)
156 {
157         if (platform_mode && hibernation_ops)
158                 hibernation_ops->leave();
159 }
160
161 /**
162  *      platform_finish - switch the machine to the normal mode of operation
163  *      using the platform driver (must be called after platform_prepare())
164  */
165
166 static void platform_finish(int platform_mode)
167 {
168         if (platform_mode && hibernation_ops)
169                 hibernation_ops->finish();
170 }
171
172 /**
173  *      platform_pre_restore - prepare the platform for the restoration from a
174  *      hibernation image.  If the restore fails after this function has been
175  *      called, platform_restore_cleanup() must be called.
176  */
177
178 static int platform_pre_restore(int platform_mode)
179 {
180         return (platform_mode && hibernation_ops) ?
181                 hibernation_ops->pre_restore() : 0;
182 }
183
184 /**
185  *      platform_restore_cleanup - switch the platform to the normal mode of
186  *      operation after a failing restore.  If platform_pre_restore() has been
187  *      called before the failing restore, this function must be called too,
188  *      regardless of the result of platform_pre_restore().
189  */
190
191 static void platform_restore_cleanup(int platform_mode)
192 {
193         if (platform_mode && hibernation_ops)
194                 hibernation_ops->restore_cleanup();
195 }
196
197 /**
198  *      platform_recover - recover the platform from a failure to suspend
199  *      devices.
200  */
201
202 static void platform_recover(int platform_mode)
203 {
204         if (platform_mode && hibernation_ops && hibernation_ops->recover)
205                 hibernation_ops->recover();
206 }
207
208 /**
209  *      swsusp_show_speed - print the time elapsed between two events.
210  *      @start: Starting event.
211  *      @stop: Final event.
212  *      @nr_pages -     number of pages processed between @start and @stop
213  *      @msg -          introductory message to print
214  */
215
216 void swsusp_show_speed(struct timeval *start, struct timeval *stop,
217                         unsigned nr_pages, char *msg)
218 {
219         s64 elapsed_centisecs64;
220         int centisecs;
221         int k;
222         int kps;
223
224         elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
225         do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
226         centisecs = elapsed_centisecs64;
227         if (centisecs == 0)
228                 centisecs = 1;  /* avoid div-by-zero */
229         k = nr_pages * (PAGE_SIZE / 1024);
230         kps = (k * 100) / centisecs;
231         printk(KERN_INFO "PM: %s %d kbytes in %d.%02d seconds (%d.%02d MB/s)\n",
232                         msg, k,
233                         centisecs / 100, centisecs % 100,
234                         kps / 1000, (kps % 1000) / 10);
235 }
236
237 /**
238  *      create_image - freeze devices that need to be frozen with interrupts
239  *      off, create the hibernation image and thaw those devices.  Control
240  *      reappears in this routine after a restore.
241  */
242
243 static int create_image(int platform_mode)
244 {
245         int error;
246
247         error = arch_prepare_suspend();
248         if (error)
249                 return error;
250
251         error = dpm_suspend_noirq(PMSG_FREEZE);
252         if (error) {
253                 printk(KERN_ERR "PM: Some devices failed to power down, "
254                         "aborting hibernation\n");
255                 return error;
256         }
257
258         error = platform_pre_snapshot(platform_mode);
259         if (error || hibernation_test(TEST_PLATFORM))
260                 goto Platform_finish;
261
262         error = disable_nonboot_cpus();
263         if (error || hibernation_test(TEST_CPUS)
264             || hibernation_testmode(HIBERNATION_TEST))
265                 goto Enable_cpus;
266
267         local_irq_disable();
268
269         error = syscore_suspend();
270         if (error) {
271                 printk(KERN_ERR "PM: Some system devices failed to power down, "
272                         "aborting hibernation\n");
273                 goto Enable_irqs;
274         }
275
276         if (hibernation_test(TEST_CORE) || pm_wakeup_pending())
277                 goto Power_up;
278
279         in_suspend = 1;
280         save_processor_state();
281         error = swsusp_arch_suspend();
282         if (error)
283                 printk(KERN_ERR "PM: Error %d creating hibernation image\n",
284                         error);
285         /* Restore control flow magically appears here */
286         restore_processor_state();
287         if (!in_suspend) {
288                 events_check_enabled = false;
289                 platform_leave(platform_mode);
290         }
291
292  Power_up:
293         syscore_resume();
294
295  Enable_irqs:
296         local_irq_enable();
297
298  Enable_cpus:
299         enable_nonboot_cpus();
300
301  Platform_finish:
302         platform_finish(platform_mode);
303
304         dpm_resume_noirq(in_suspend ?
305                 (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
306
307         return error;
308 }
309
310 /**
311  *      hibernation_snapshot - quiesce devices and create the hibernation
312  *      snapshot image.
313  *      @platform_mode - if set, use the platform driver, if available, to
314  *                       prepare the platform firmware for the power transition.
315  *
316  *      Must be called with pm_mutex held
317  */
318
319 int hibernation_snapshot(int platform_mode)
320 {
321         pm_message_t msg = PMSG_RECOVER;
322         int error;
323
324         error = platform_begin(platform_mode);
325         if (error)
326                 goto Close;
327
328         error = dpm_prepare(PMSG_FREEZE);
329         if (error)
330                 goto Complete_devices;
331
332         /* Preallocate image memory before shutting down devices. */
333         error = hibernate_preallocate_memory();
334         if (error)
335                 goto Complete_devices;
336
337         suspend_console();
338         pm_restrict_gfp_mask();
339         error = dpm_suspend(PMSG_FREEZE);
340         if (error)
341                 goto Recover_platform;
342
343         if (hibernation_test(TEST_DEVICES))
344                 goto Recover_platform;
345
346         error = create_image(platform_mode);
347         /*
348          * Control returns here (1) after the image has been created or the
349          * image creation has failed and (2) after a successful restore.
350          */
351
352  Resume_devices:
353         /* We may need to release the preallocated image pages here. */
354         if (error || !in_suspend)
355                 swsusp_free();
356
357         msg = in_suspend ? (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE;
358         dpm_resume(msg);
359
360         if (error || !in_suspend)
361                 pm_restore_gfp_mask();
362
363         resume_console();
364
365  Complete_devices:
366         dpm_complete(msg);
367
368  Close:
369         platform_end(platform_mode);
370         return error;
371
372  Recover_platform:
373         platform_recover(platform_mode);
374         goto Resume_devices;
375 }
376
377 /**
378  *      resume_target_kernel - prepare devices that need to be suspended with
379  *      interrupts off, restore the contents of highmem that have not been
380  *      restored yet from the image and run the low level code that will restore
381  *      the remaining contents of memory and switch to the just restored target
382  *      kernel.
383  */
384
385 static int resume_target_kernel(bool platform_mode)
386 {
387         int error;
388
389         error = dpm_suspend_noirq(PMSG_QUIESCE);
390         if (error) {
391                 printk(KERN_ERR "PM: Some devices failed to power down, "
392                         "aborting resume\n");
393                 return error;
394         }
395
396         error = platform_pre_restore(platform_mode);
397         if (error)
398                 goto Cleanup;
399
400         error = disable_nonboot_cpus();
401         if (error)
402                 goto Enable_cpus;
403
404         local_irq_disable();
405
406         error = syscore_suspend();
407         if (error)
408                 goto Enable_irqs;
409
410         save_processor_state();
411         error = restore_highmem();
412         if (!error) {
413                 error = swsusp_arch_resume();
414                 /*
415                  * The code below is only ever reached in case of a failure.
416                  * Otherwise, execution continues at the place where
417                  * swsusp_arch_suspend() was called.
418                  */
419                 BUG_ON(!error);
420                 /*
421                  * This call to restore_highmem() reverts the changes made by
422                  * the previous one.
423                  */
424                 restore_highmem();
425         }
426         /*
427          * The only reason why swsusp_arch_resume() can fail is memory being
428          * very tight, so we have to free it as soon as we can to avoid
429          * subsequent failures.
430          */
431         swsusp_free();
432         restore_processor_state();
433         touch_softlockup_watchdog();
434
435         syscore_resume();
436
437  Enable_irqs:
438         local_irq_enable();
439
440  Enable_cpus:
441         enable_nonboot_cpus();
442
443  Cleanup:
444         platform_restore_cleanup(platform_mode);
445
446         dpm_resume_noirq(PMSG_RECOVER);
447
448         return error;
449 }
450
451 /**
452  *      hibernation_restore - quiesce devices and restore the hibernation
453  *      snapshot image.  If successful, control returns in hibernation_snaphot()
454  *      @platform_mode - if set, use the platform driver, if available, to
455  *                       prepare the platform firmware for the transition.
456  *
457  *      Must be called with pm_mutex held
458  */
459
460 int hibernation_restore(int platform_mode)
461 {
462         int error;
463
464         pm_prepare_console();
465         suspend_console();
466         pm_restrict_gfp_mask();
467         error = dpm_suspend_start(PMSG_QUIESCE);
468         if (!error) {
469                 error = resume_target_kernel(platform_mode);
470                 dpm_resume_end(PMSG_RECOVER);
471         }
472         pm_restore_gfp_mask();
473         resume_console();
474         pm_restore_console();
475         return error;
476 }
477
478 /**
479  *      hibernation_platform_enter - enter the hibernation state using the
480  *      platform driver (if available)
481  */
482
483 int hibernation_platform_enter(void)
484 {
485         int error;
486
487         if (!hibernation_ops)
488                 return -ENOSYS;
489
490         /*
491          * We have cancelled the power transition by running
492          * hibernation_ops->finish() before saving the image, so we should let
493          * the firmware know that we're going to enter the sleep state after all
494          */
495         error = hibernation_ops->begin();
496         if (error)
497                 goto Close;
498
499         entering_platform_hibernation = true;
500         suspend_console();
501         error = dpm_suspend_start(PMSG_HIBERNATE);
502         if (error) {
503                 if (hibernation_ops->recover)
504                         hibernation_ops->recover();
505                 goto Resume_devices;
506         }
507
508         error = dpm_suspend_noirq(PMSG_HIBERNATE);
509         if (error)
510                 goto Resume_devices;
511
512         error = hibernation_ops->prepare();
513         if (error)
514                 goto Platform_finish;
515
516         error = disable_nonboot_cpus();
517         if (error)
518                 goto Platform_finish;
519
520         local_irq_disable();
521         syscore_suspend();
522         if (pm_wakeup_pending()) {
523                 error = -EAGAIN;
524                 goto Power_up;
525         }
526
527         hibernation_ops->enter();
528         /* We should never get here */
529         while (1);
530
531  Power_up:
532         syscore_resume();
533         local_irq_enable();
534         enable_nonboot_cpus();
535
536  Platform_finish:
537         hibernation_ops->finish();
538
539         dpm_resume_noirq(PMSG_RESTORE);
540
541  Resume_devices:
542         entering_platform_hibernation = false;
543         dpm_resume_end(PMSG_RESTORE);
544         resume_console();
545
546  Close:
547         hibernation_ops->end();
548
549         return error;
550 }
551
552 /**
553  *      power_down - Shut the machine down for hibernation.
554  *
555  *      Use the platform driver, if configured so; otherwise try
556  *      to power off or reboot.
557  */
558
559 static void power_down(void)
560 {
561         switch (hibernation_mode) {
562         case HIBERNATION_TEST:
563         case HIBERNATION_TESTPROC:
564                 break;
565         case HIBERNATION_REBOOT:
566                 kernel_restart(NULL);
567                 break;
568         case HIBERNATION_PLATFORM:
569                 hibernation_platform_enter();
570         case HIBERNATION_SHUTDOWN:
571                 kernel_power_off();
572                 break;
573         }
574         kernel_halt();
575         /*
576          * Valid image is on the disk, if we continue we risk serious data
577          * corruption after resume.
578          */
579         printk(KERN_CRIT "PM: Please power down manually\n");
580         while(1);
581 }
582
583 static int prepare_processes(void)
584 {
585         int error = 0;
586
587         if (freeze_processes()) {
588                 error = -EBUSY;
589                 thaw_processes();
590         }
591         return error;
592 }
593
594 /**
595  *      hibernate - The granpappy of the built-in hibernation management
596  */
597
598 int hibernate(void)
599 {
600         int error;
601
602         mutex_lock(&pm_mutex);
603         /* The snapshot device should not be opened while we're running */
604         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
605                 error = -EBUSY;
606                 goto Unlock;
607         }
608
609         pm_prepare_console();
610         error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
611         if (error)
612                 goto Exit;
613
614         error = usermodehelper_disable();
615         if (error)
616                 goto Exit;
617
618         /* Allocate memory management structures */
619         error = create_basic_memory_bitmaps();
620         if (error)
621                 goto Exit;
622
623         printk(KERN_INFO "PM: Syncing filesystems ... ");
624         sys_sync();
625         printk("done.\n");
626
627         error = prepare_processes();
628         if (error)
629                 goto Finish;
630
631         if (hibernation_test(TEST_FREEZER))
632                 goto Thaw;
633
634         if (hibernation_testmode(HIBERNATION_TESTPROC))
635                 goto Thaw;
636
637         error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
638         if (error)
639                 goto Thaw;
640
641         if (in_suspend) {
642                 unsigned int flags = 0;
643
644                 if (hibernation_mode == HIBERNATION_PLATFORM)
645                         flags |= SF_PLATFORM_MODE;
646                 if (nocompress)
647                         flags |= SF_NOCOMPRESS_MODE;
648                 pr_debug("PM: writing image.\n");
649                 error = swsusp_write(flags);
650                 swsusp_free();
651                 if (!error)
652                         power_down();
653                 in_suspend = 0;
654                 pm_restore_gfp_mask();
655         } else {
656                 pr_debug("PM: Image restored successfully.\n");
657         }
658
659  Thaw:
660         thaw_processes();
661  Finish:
662         free_basic_memory_bitmaps();
663         usermodehelper_enable();
664  Exit:
665         pm_notifier_call_chain(PM_POST_HIBERNATION);
666         pm_restore_console();
667         atomic_inc(&snapshot_device_available);
668  Unlock:
669         mutex_unlock(&pm_mutex);
670         return error;
671 }
672
673
674 /**
675  *      software_resume - Resume from a saved image.
676  *
677  *      Called as a late_initcall (so all devices are discovered and
678  *      initialized), we call swsusp to see if we have a saved image or not.
679  *      If so, we quiesce devices, the restore the saved image. We will
680  *      return above (in hibernate() ) if everything goes well.
681  *      Otherwise, we fail gracefully and return to the normally
682  *      scheduled program.
683  *
684  */
685
686 static int software_resume(void)
687 {
688         int error;
689         unsigned int flags;
690
691         /*
692          * If the user said "noresume".. bail out early.
693          */
694         if (noresume)
695                 return 0;
696
697         /*
698          * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
699          * is configured into the kernel. Since the regular hibernate
700          * trigger path is via sysfs which takes a buffer mutex before
701          * calling hibernate functions (which take pm_mutex) this can
702          * cause lockdep to complain about a possible ABBA deadlock
703          * which cannot happen since we're in the boot code here and
704          * sysfs can't be invoked yet. Therefore, we use a subclass
705          * here to avoid lockdep complaining.
706          */
707         mutex_lock_nested(&pm_mutex, SINGLE_DEPTH_NESTING);
708
709         if (swsusp_resume_device)
710                 goto Check_image;
711
712         if (!strlen(resume_file)) {
713                 error = -ENOENT;
714                 goto Unlock;
715         }
716
717         pr_debug("PM: Checking hibernation image partition %s\n", resume_file);
718
719         /* Check if the device is there */
720         swsusp_resume_device = name_to_dev_t(resume_file);
721         if (!swsusp_resume_device) {
722                 /*
723                  * Some device discovery might still be in progress; we need
724                  * to wait for this to finish.
725                  */
726                 wait_for_device_probe();
727                 /*
728                  * We can't depend on SCSI devices being available after loading
729                  * one of their modules until scsi_complete_async_scans() is
730                  * called and the resume device usually is a SCSI one.
731                  */
732                 scsi_complete_async_scans();
733
734                 swsusp_resume_device = name_to_dev_t(resume_file);
735                 if (!swsusp_resume_device) {
736                         error = -ENODEV;
737                         goto Unlock;
738                 }
739         }
740
741  Check_image:
742         pr_debug("PM: Hibernation image partition %d:%d present\n",
743                 MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
744
745         pr_debug("PM: Looking for hibernation image.\n");
746         error = swsusp_check();
747         if (error)
748                 goto Unlock;
749
750         /* The snapshot device should not be opened while we're running */
751         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
752                 error = -EBUSY;
753                 swsusp_close(FMODE_READ);
754                 goto Unlock;
755         }
756
757         pm_prepare_console();
758         error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
759         if (error)
760                 goto close_finish;
761
762         error = usermodehelper_disable();
763         if (error)
764                 goto close_finish;
765
766         error = create_basic_memory_bitmaps();
767         if (error)
768                 goto close_finish;
769
770         pr_debug("PM: Preparing processes for restore.\n");
771         error = prepare_processes();
772         if (error) {
773                 swsusp_close(FMODE_READ);
774                 goto Done;
775         }
776
777         pr_debug("PM: Loading hibernation image.\n");
778
779         error = swsusp_read(&flags);
780         swsusp_close(FMODE_READ);
781         if (!error)
782                 hibernation_restore(flags & SF_PLATFORM_MODE);
783
784         printk(KERN_ERR "PM: Failed to load hibernation image, recovering.\n");
785         swsusp_free();
786         thaw_processes();
787  Done:
788         free_basic_memory_bitmaps();
789         usermodehelper_enable();
790  Finish:
791         pm_notifier_call_chain(PM_POST_RESTORE);
792         pm_restore_console();
793         atomic_inc(&snapshot_device_available);
794         /* For success case, the suspend path will release the lock */
795  Unlock:
796         mutex_unlock(&pm_mutex);
797         pr_debug("PM: Hibernation image not present or could not be loaded.\n");
798         return error;
799 close_finish:
800         swsusp_close(FMODE_READ);
801         goto Finish;
802 }
803
804 late_initcall(software_resume);
805
806
807 static const char * const hibernation_modes[] = {
808         [HIBERNATION_PLATFORM]  = "platform",
809         [HIBERNATION_SHUTDOWN]  = "shutdown",
810         [HIBERNATION_REBOOT]    = "reboot",
811         [HIBERNATION_TEST]      = "test",
812         [HIBERNATION_TESTPROC]  = "testproc",
813 };
814
815 /**
816  *      disk - Control hibernation mode
817  *
818  *      Suspend-to-disk can be handled in several ways. We have a few options
819  *      for putting the system to sleep - using the platform driver (e.g. ACPI
820  *      or other hibernation_ops), powering off the system or rebooting the
821  *      system (for testing) as well as the two test modes.
822  *
823  *      The system can support 'platform', and that is known a priori (and
824  *      encoded by the presence of hibernation_ops). However, the user may
825  *      choose 'shutdown' or 'reboot' as alternatives, as well as one fo the
826  *      test modes, 'test' or 'testproc'.
827  *
828  *      show() will display what the mode is currently set to.
829  *      store() will accept one of
830  *
831  *      'platform'
832  *      'shutdown'
833  *      'reboot'
834  *      'test'
835  *      'testproc'
836  *
837  *      It will only change to 'platform' if the system
838  *      supports it (as determined by having hibernation_ops).
839  */
840
841 static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
842                          char *buf)
843 {
844         int i;
845         char *start = buf;
846
847         for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
848                 if (!hibernation_modes[i])
849                         continue;
850                 switch (i) {
851                 case HIBERNATION_SHUTDOWN:
852                 case HIBERNATION_REBOOT:
853                 case HIBERNATION_TEST:
854                 case HIBERNATION_TESTPROC:
855                         break;
856                 case HIBERNATION_PLATFORM:
857                         if (hibernation_ops)
858                                 break;
859                         /* not a valid mode, continue with loop */
860                         continue;
861                 }
862                 if (i == hibernation_mode)
863                         buf += sprintf(buf, "[%s] ", hibernation_modes[i]);
864                 else
865                         buf += sprintf(buf, "%s ", hibernation_modes[i]);
866         }
867         buf += sprintf(buf, "\n");
868         return buf-start;
869 }
870
871
872 static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
873                           const char *buf, size_t n)
874 {
875         int error = 0;
876         int i;
877         int len;
878         char *p;
879         int mode = HIBERNATION_INVALID;
880
881         p = memchr(buf, '\n', n);
882         len = p ? p - buf : n;
883
884         mutex_lock(&pm_mutex);
885         for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
886                 if (len == strlen(hibernation_modes[i])
887                     && !strncmp(buf, hibernation_modes[i], len)) {
888                         mode = i;
889                         break;
890                 }
891         }
892         if (mode != HIBERNATION_INVALID) {
893                 switch (mode) {
894                 case HIBERNATION_SHUTDOWN:
895                 case HIBERNATION_REBOOT:
896                 case HIBERNATION_TEST:
897                 case HIBERNATION_TESTPROC:
898                         hibernation_mode = mode;
899                         break;
900                 case HIBERNATION_PLATFORM:
901                         if (hibernation_ops)
902                                 hibernation_mode = mode;
903                         else
904                                 error = -EINVAL;
905                 }
906         } else
907                 error = -EINVAL;
908
909         if (!error)
910                 pr_debug("PM: Hibernation mode set to '%s'\n",
911                          hibernation_modes[mode]);
912         mutex_unlock(&pm_mutex);
913         return error ? error : n;
914 }
915
916 power_attr(disk);
917
918 static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
919                            char *buf)
920 {
921         return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
922                        MINOR(swsusp_resume_device));
923 }
924
925 static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
926                             const char *buf, size_t n)
927 {
928         unsigned int maj, min;
929         dev_t res;
930         int ret = -EINVAL;
931
932         if (sscanf(buf, "%u:%u", &maj, &min) != 2)
933                 goto out;
934
935         res = MKDEV(maj,min);
936         if (maj != MAJOR(res) || min != MINOR(res))
937                 goto out;
938
939         mutex_lock(&pm_mutex);
940         swsusp_resume_device = res;
941         mutex_unlock(&pm_mutex);
942         printk(KERN_INFO "PM: Starting manual resume from disk\n");
943         noresume = 0;
944         software_resume();
945         ret = n;
946  out:
947         return ret;
948 }
949
950 power_attr(resume);
951
952 static ssize_t image_size_show(struct kobject *kobj, struct kobj_attribute *attr,
953                                char *buf)
954 {
955         return sprintf(buf, "%lu\n", image_size);
956 }
957
958 static ssize_t image_size_store(struct kobject *kobj, struct kobj_attribute *attr,
959                                 const char *buf, size_t n)
960 {
961         unsigned long size;
962
963         if (sscanf(buf, "%lu", &size) == 1) {
964                 image_size = size;
965                 return n;
966         }
967
968         return -EINVAL;
969 }
970
971 power_attr(image_size);
972
973 static ssize_t reserved_size_show(struct kobject *kobj,
974                                   struct kobj_attribute *attr, char *buf)
975 {
976         return sprintf(buf, "%lu\n", reserved_size);
977 }
978
979 static ssize_t reserved_size_store(struct kobject *kobj,
980                                    struct kobj_attribute *attr,
981                                    const char *buf, size_t n)
982 {
983         unsigned long size;
984
985         if (sscanf(buf, "%lu", &size) == 1) {
986                 reserved_size = size;
987                 return n;
988         }
989
990         return -EINVAL;
991 }
992
993 power_attr(reserved_size);
994
995 static struct attribute * g[] = {
996         &disk_attr.attr,
997         &resume_attr.attr,
998         &image_size_attr.attr,
999         &reserved_size_attr.attr,
1000         NULL,
1001 };
1002
1003
1004 static struct attribute_group attr_group = {
1005         .attrs = g,
1006 };
1007
1008
1009 static int __init pm_disk_init(void)
1010 {
1011         return sysfs_create_group(power_kobj, &attr_group);
1012 }
1013
1014 core_initcall(pm_disk_init);
1015
1016
1017 static int __init resume_setup(char *str)
1018 {
1019         if (noresume)
1020                 return 1;
1021
1022         strncpy( resume_file, str, 255 );
1023         return 1;
1024 }
1025
1026 static int __init resume_offset_setup(char *str)
1027 {
1028         unsigned long long offset;
1029
1030         if (noresume)
1031                 return 1;
1032
1033         if (sscanf(str, "%llu", &offset) == 1)
1034                 swsusp_resume_block = offset;
1035
1036         return 1;
1037 }
1038
1039 static int __init hibernate_setup(char *str)
1040 {
1041         if (!strncmp(str, "noresume", 8))
1042                 noresume = 1;
1043         else if (!strncmp(str, "nocompress", 10))
1044                 nocompress = 1;
1045         return 1;
1046 }
1047
1048 static int __init noresume_setup(char *str)
1049 {
1050         noresume = 1;
1051         return 1;
1052 }
1053
1054 __setup("noresume", noresume_setup);
1055 __setup("resume_offset=", resume_offset_setup);
1056 __setup("resume=", resume_setup);
1057 __setup("hibernate=", hibernate_setup);