summaryrefslogtreecommitdiff
path: root/drivers/acpi/battery.c
blob: 9b2c0f74f869a6c4ce74e64462432c24ebf770b0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
/*
 *  acpi_battery.c - ACPI Battery Driver ($Revision: 37 $)
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/uaccess.h>

#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>

#define ACPI_BATTERY_VALUE_UNKNOWN 0xFFFFFFFF

#define ACPI_BATTERY_FORMAT_BIF	"NNNNNNNNNSSSS"
#define ACPI_BATTERY_FORMAT_BST	"NNNN"

#define ACPI_BATTERY_COMPONENT		0x00040000
#define ACPI_BATTERY_CLASS		"battery"
#define ACPI_BATTERY_DEVICE_NAME	"Battery"
#define ACPI_BATTERY_NOTIFY_STATUS	0x80
#define ACPI_BATTERY_NOTIFY_INFO	0x81
#define ACPI_BATTERY_UNITS_WATTS	"mW"
#define ACPI_BATTERY_UNITS_AMPS		"mA"

#define _COMPONENT		ACPI_BATTERY_COMPONENT

#define ACPI_BATTERY_UPDATE_TIME	0

#define ACPI_BATTERY_NONE_UPDATE	0
#define ACPI_BATTERY_EASY_UPDATE	1
#define ACPI_BATTERY_INIT_UPDATE	2

ACPI_MODULE_NAME("battery");

MODULE_AUTHOR("Paul Diefenbaugh");
MODULE_DESCRIPTION("ACPI Battery Driver");
MODULE_LICENSE("GPL");

static unsigned int update_time = ACPI_BATTERY_UPDATE_TIME;

/* 0 - every time, > 0 - by update_time */
module_param(update_time, uint, 0644);

extern struct proc_dir_entry *acpi_lock_battery_dir(void);
extern void *acpi_unlock_battery_dir(struct proc_dir_entry *acpi_battery_dir);

static int acpi_battery_add(struct acpi_device *device);
static int acpi_battery_remove(struct acpi_device *device, int type);
static int acpi_battery_resume(struct acpi_device *device);

static const struct acpi_device_id battery_device_ids[] = {
	{"PNP0C0A", 0},
	{"", 0},
};
MODULE_DEVICE_TABLE(acpi, battery_device_ids);

static struct acpi_driver acpi_battery_driver = {
	.name = "battery",
	.class = ACPI_BATTERY_CLASS,
	.ids = battery_device_ids,
	.ops = {
		.add = acpi_battery_add,
		.resume = acpi_battery_resume,
		.remove = acpi_battery_remove,
		},
};

struct acpi_battery_state {
	acpi_integer state;
	acpi_integer present_rate;
	acpi_integer remaining_capacity;
	acpi_integer present_voltage;
};

struct acpi_battery_info {
	acpi_integer power_unit;
	acpi_integer design_capacity;
	acpi_integer last_full_capacity;
	acpi_integer battery_technology;
	acpi_integer design_voltage;
	acpi_integer design_capacity_warning;
	acpi_integer design_capacity_low;
	acpi_integer battery_capacity_granularity_1;
	acpi_integer battery_capacity_granularity_2;
	acpi_string model_number;
	acpi_string serial_number;
	acpi_string battery_type;
	acpi_string oem_info;
};

enum acpi_battery_files{
	ACPI_BATTERY_INFO = 0,
	ACPI_BATTERY_STATE,
	ACPI_BATTERY_ALARM,
	ACPI_BATTERY_NUMFILES,
};

struct acpi_battery_flags {
	u8 battery_present_prev;
	u8 alarm_present;
	u8 init_update;
	u8 update[ACPI_BATTERY_NUMFILES];
	u8 power_unit;
};

struct acpi_battery {
	struct mutex mutex;
	struct acpi_device *device;
	struct acpi_battery_flags flags;
	struct acpi_buffer bif_data;
	struct acpi_buffer bst_data;
	unsigned long alarm;
	unsigned long update_time[ACPI_BATTERY_NUMFILES];
};

inline int acpi_battery_present(struct acpi_battery *battery)
{
	return battery->device->status.battery_present;
}
inline char *acpi_battery_power_units(struct acpi_battery *battery)
{
	if (battery->flags.power_unit)
		return ACPI_BATTERY_UNITS_AMPS;
	else
		return ACPI_BATTERY_UNITS_WATTS;
}

inline acpi_handle acpi_battery_handle(struct acpi_battery *battery)
{
	return battery->device->handle;
}

/* --------------------------------------------------------------------------
                               Battery Management
   -------------------------------------------------------------------------- */

static void acpi_battery_check_result(struct acpi_battery *battery, int result)
{
	if (!battery)
		return;

	if (result) {
		battery->flags.init_update = 1;
	}
}

static int acpi_battery_extract_package(struct acpi_battery *battery,
					union acpi_object *package,
					struct acpi_buffer *format,
					struct acpi_buffer *data,
					char *package_name)
{
	acpi_status status = AE_OK;
	struct acpi_buffer data_null = { 0, NULL };

	status = acpi_extract_package(package, format, &data_null);
	if (status != AE_BUFFER_OVERFLOW) {
		ACPI_EXCEPTION((AE_INFO, status, "Extracting size %s",
				package_name));
		return -ENODEV;
	}

	if (data_null.length != data->length) {
		kfree(data->pointer);
		data->pointer = kzalloc(data_null.length, GFP_KERNEL);
		if (!data->pointer) {
			ACPI_EXCEPTION((AE_INFO, AE_NO_MEMORY, "kzalloc()"));
			return -ENOMEM;
		}
		data->length = data_null.length;
	}

	status = acpi_extract_package(package, format, data);
	if (ACPI_FAILURE(status)) {
		ACPI_EXCEPTION((AE_INFO, status, "Extracting %s",
				package_name));
		return -ENODEV;
	}

	return 0;
}

static int acpi_battery_get_status(struct acpi_battery *battery)
{
	int result = 0;

	result = acpi_bus_get_status(battery->device);
	if (result) {
		ACPI_EXCEPTION((AE_INFO, AE_ERROR, "Evaluating _STA"));
		return -ENODEV;
	}
	return result;
}

static int acpi_battery_get_info(struct acpi_battery *battery)
{
	int result = 0;
	acpi_status status = 0;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	struct acpi_buffer format = { sizeof(ACPI_BATTERY_FORMAT_BIF),
		ACPI_BATTERY_FORMAT_BIF
	};
	union acpi_object *package = NULL;
	struct acpi_buffer *data = NULL;
	struct acpi_battery_info *bif = NULL;

	battery->update_time[ACPI_BATTERY_INFO] = get_seconds();

	if (!acpi_battery_present(battery))
		return 0;

	/* Evaluate _BIF */

	status =
	    acpi_evaluate_object(acpi_battery_handle(battery), "_BIF", NULL,
				 &buffer);
	if (ACPI_FAILURE(status)) {
		ACPI_EXCEPTION((AE_INFO, status, "Evaluating _BIF"));
		return -ENODEV;
	}

	package = buffer.pointer;

	data = &battery->bif_data;

	/* Extract Package Data */

	result =
	    acpi_battery_extract_package(battery, package, &format, data,
					 "_BIF");
	if (result)
		goto end;

      end:

	kfree(buffer.pointer);

	if (!result) {
		bif = data->pointer;
		battery->flags.power_unit = bif->power_unit;
	}

	return result;
}

static int acpi_battery_get_state(struct acpi_battery *battery)
{
	int result = 0;
	acpi_status status = 0;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	struct acpi_buffer format = { sizeof(ACPI_BATTERY_FORMAT_BST),
		ACPI_BATTERY_FORMAT_BST
	};
	union acpi_object *package = NULL;
	struct acpi_buffer *data = NULL;

	battery->update_time[ACPI_BATTERY_STATE] = get_seconds();

	if (!acpi_battery_present(battery))
		return 0;

	/* Evaluate _BST */

	status =
	    acpi_evaluate_object(acpi_battery_handle(battery), "_BST", NULL,
				 &buffer);
	if (ACPI_FAILURE(status)) {
		ACPI_EXCEPTION((AE_INFO, status, "Evaluating _BST"));
		return -ENODEV;
	}

	package = buffer.pointer;

	data = &battery->bst_data;

	/* Extract Package Data */

	result =
	    acpi_battery_extract_package(battery, package, &format, data,
					 "_BST");
	if (result)
		goto end;

      end:
	kfree(buffer.pointer);

	return result;
}

static int acpi_battery_get_alarm(struct acpi_battery *battery)
{
	battery->update_time[ACPI_BATTERY_ALARM] = get_seconds();

	return 0;
}

static int acpi_battery_set_alarm(struct acpi_battery *battery,
				  unsigned long alarm)
{
	acpi_status status = 0;
	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
	struct acpi_object_list arg_list = { 1, &arg0 };

	battery->update_time[ACPI_BATTERY_ALARM] = get_seconds();

	if (!acpi_battery_present(battery))
		return -ENODEV;

	if (!battery->flags.alarm_present)
		return -ENODEV;

	arg0.integer.value = alarm;

	status =
	    acpi_evaluate_object(acpi_battery_handle(battery), "_BTP",
				 &arg_list, NULL);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Alarm set to %d\n", (u32) alarm));

	battery->alarm = alarm;

	return 0;
}

static int acpi_battery_init_alarm(struct acpi_battery *battery)
{
	int result = 0;
	acpi_status status = AE_OK;
	acpi_handle handle = NULL;
	struct acpi_battery_info *bif = battery->bif_data.pointer;
	unsigned long alarm = battery->alarm;

	/* See if alarms are supported, and if so, set default */

	status = acpi_get_handle(acpi_battery_handle(battery), "_BTP", &handle);
	if (ACPI_SUCCESS(status)) {
		battery->flags.alarm_present = 1;
		if (!alarm && bif) {
			alarm = bif->design_capacity_warning;
		}
		result = acpi_battery_set_alarm(battery, alarm);
		if (result)
			goto end;
	} else {
		battery->flags.alarm_present = 0;
	}

      end:

	return result;
}

static int acpi_battery_init_update(struct acpi_battery *battery)
{
	int result = 0;

	result = acpi_battery_get_status(battery);
	if (result)
		return result;

	battery->flags.battery_present_prev = acpi_battery_present(battery);

	if (acpi_battery_present(battery)) {
		result = acpi_battery_get_info(battery);
		if (result)
			return result;
		result = acpi_battery_get_state(battery);
		if (result)
			return result;

		acpi_battery_init_alarm(battery);
	}

	return result;
}

static int acpi_battery_update(struct acpi_battery *battery,
			       int update, int *update_result_ptr)
{
	int result = 0;
	int update_result = ACPI_BATTERY_NONE_UPDATE;

	if (!acpi_battery_present(battery)) {
		update = 1;
	}

	if (battery->flags.init_update) {
		result = acpi_battery_init_update(battery);
		if (result)
			goto end;
		update_result = ACPI_BATTERY_INIT_UPDATE;
	} else if (update) {
		result = acpi_battery_get_status(battery);
		if (result)
			goto end;
		if ((!battery->flags.battery_present_prev & acpi_battery_present(battery))
		    || (battery->flags.battery_present_prev & !acpi_battery_present(battery))) {
			result = acpi_battery_init_update(battery);
			if (result)
				goto end;
			update_result = ACPI_BATTERY_INIT_UPDATE;
		} else {
			update_result = ACPI_BATTERY_EASY_UPDATE;
		}
	}

      end:

	battery->flags.init_update = (result != 0);

	*update_result_ptr = update_result;

	return result;
}

static void acpi_battery_notify_update(struct acpi_battery *battery)
{
	acpi_battery_get_status(battery);

	if (battery->flags.init_update) {
		return;
	}

	if ((!battery->flags.battery_present_prev &
	     acpi_battery_present(battery)) ||
	    (battery->flags.battery_present_prev &
	     !acpi_battery_present(battery))) {
		battery->flags.init_update = 1;
	} else {
		battery->flags.update[ACPI_BATTERY_INFO] = 1;
		battery->flags.update[ACPI_BATTERY_STATE] = 1;
		battery->flags.update[ACPI_BATTERY_ALARM] = 1;
	}
}

/* --------------------------------------------------------------------------
                              FS Interface (/proc)
   -------------------------------------------------------------------------- */

static struct proc_dir_entry *acpi_battery_dir;

static int acpi_battery_print_info(struct seq_file *seq, int result)
{
	struct acpi_battery *battery = seq->private;
	struct acpi_battery_info *bif = NULL;
	char *units = "?";

	if (result)
		goto end;

	if (acpi_battery_present(battery))
		seq_printf(seq, "present:                 yes\n");
	else {
		seq_printf(seq, "present:                 no\n");
		goto end;
	}

	bif = battery->bif_data.pointer;
	if (!bif) {
		ACPI_EXCEPTION((AE_INFO, AE_ERROR, "BIF buffer is NULL"));
		result = -ENODEV;
		goto end;
	}

	/* Battery Units */

	units = acpi_battery_power_units(battery);

	if (bif->design_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
		seq_printf(seq, "design capacity:         unknown\n");
	else
		seq_printf(seq, "design capacity:         %d %sh\n",
			   (u32) bif->design_capacity, units);

	if (bif->last_full_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
		seq_printf(seq, "last full capacity:      unknown\n");
	else
		seq_printf(seq, "last full capacity:      %d %sh\n",
			   (u32) bif->last_full_capacity, units);

	switch ((u32) bif->battery_technology) {
	case 0:
		seq_printf(seq, "battery technology:      non-rechargeable\n");
		break;
	case 1:
		seq_printf(seq, "battery technology:      rechargeable\n");
		break;
	default:
		seq_printf(seq, "battery technology:      unknown\n");
		break;
	}

	if (bif->design_voltage == ACPI_BATTERY_VALUE_UNKNOWN)
		seq_printf(seq, "design voltage:          unknown\n");
	else
		seq_printf(seq, "design voltage:          %d mV\n",
			   (u32) bif->design_voltage);
	seq_printf(seq, "design capacity warning: %d %sh\n",
		   (u32) bif->design_capacity_warning, units);
	seq_printf(seq, "design capacity low:     %d %sh\n",
		   (u32) bif->design_capacity_low, units);
	seq_printf(seq, "capacity granularity 1:  %d %sh\n",
		   (u32) bif->battery_capacity_granularity_1, units);
	seq_printf(seq, "capacity granularity 2:  %d %sh\n",
		   (u32) bif->battery_capacity_granularity_2, units);
	seq_printf(seq, "model number:            %s\n", bif->model_number);
	seq_printf(seq, "serial number:           %s\n", bif->serial_number);
	seq_printf(seq, "battery type:            %s\n", bif->battery_type);
	seq_printf(seq, "OEM info:                %s\n", bif->oem_info);

      end:

	if (result)
		seq_printf(seq, "ERROR: Unable to read battery info\n");

	return result;
}

static int acpi_battery_print_state(struct seq_file *seq, int result)
{
	struct acpi_battery *battery = seq->private;
	struct acpi_battery_state *bst = NULL;
	char *units = "?";

	if (result)
		goto end;

	if (acpi_battery_present(battery))
		seq_printf(seq, "present:                 yes\n");
	else {
		seq_printf(seq, "present:                 no\n");
		goto end;
	}

	bst = battery->bst_data.pointer;
	if (!bst) {
		ACPI_EXCEPTION((AE_INFO, AE_ERROR, "BST buffer is NULL"));
		result = -ENODEV;
		goto end;
	}

	/* Battery Units */

	units = acpi_battery_power_units(battery);

	if (!(bst->state & 0x04))
		seq_printf(seq, "capacity state:          ok\n");
	else
		seq_printf(seq, "capacity state:          critical\n");

	if ((bst->state & 0x01) && (bst->state & 0x02)) {
		seq_printf(seq,
			   "charging state:          charging/discharging\n");
	} else if (bst->state & 0x01)
		seq_printf(seq, "charging state:          discharging\n");
	else if (bst->state & 0x02)
		seq_printf(seq, "charging state:          charging\n");
	else {
		seq_printf(seq, "charging state:          charged\n");
	}

	if (bst->present_rate == ACPI_BATTERY_VALUE_UNKNOWN)
		seq_printf(seq, "present rate:            unknown\n");
	else
		seq_printf(seq, "present rate:            %d %s\n",
			   (u32) bst->present_rate, units);

	if (bst->remaining_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
		seq_printf(seq, "remaining capacity:      unknown\n");
	else
		seq_printf(seq, "remaining capacity:      %d %sh\n",
			   (u32) bst->remaining_capacity, units);

	if (bst->present_voltage == ACPI_BATTERY_VALUE_UNKNOWN)
		seq_printf(seq, "present voltage:         unknown\n");
	else
		seq_printf(seq, "present voltage:         %d mV\n",
			   (u32) bst->present_voltage);

      end:

	if (result) {
		seq_printf(seq, "ERROR: Unable to read battery state\n");
	}

	return result;
}

static int acpi_battery_print_alarm(struct seq_file *seq, int result)
{
	struct acpi_battery *battery = seq->private;
	char *units = "?";

	if (result)
		goto end;

	if (!acpi_battery_present(battery)) {
		seq_printf(seq, "present:                 no\n");
		goto end;
	}

	/* Battery Units */

	units = acpi_battery_power_units(battery);

	seq_printf(seq, "alarm:                   ");
	if (!battery->alarm)
		seq_printf(seq, "unsupported\n");
	else
		seq_printf(seq, "%lu %sh\n", battery->alarm, units);

      end:

	if (result)
		seq_printf(seq, "ERROR: Unable to read battery alarm\n");

	return result;
}

static ssize_t
acpi_battery_write_alarm(struct file *file,
			 const char __user * buffer,
			 size_t count, loff_t * ppos)
{
	int result = 0;
	char alarm_string[12] = { '\0' };
	struct seq_file *m = file->private_data;
	struct acpi_battery *battery = m->private;
	int update_result = ACPI_BATTERY_NONE_UPDATE;

	if (!battery || (count > sizeof(alarm_string) - 1))
		return -EINVAL;

	mutex_lock(&battery->mutex);

	result = acpi_battery_update(battery, 1, &update_result);
	if (result) {
		result = -ENODEV;
		goto end;
	}

	if (!acpi_battery_present(battery)) {
		result = -ENODEV;
		goto end;
	}

	if (copy_from_user(alarm_string, buffer, count)) {
		result = -EFAULT;
		goto end;
	}

	alarm_string[count] = '\0';

	result = acpi_battery_set_alarm(battery,
					simple_strtoul(alarm_string, NULL, 0));
	if (result)
		goto end;

      end:

	acpi_battery_check_result(battery, result);

	if (!result)
		result = count;

	mutex_unlock(&battery->mutex);

	return result;
}

typedef int(*print_func)(struct seq_file *seq, int result);
typedef int(*get_func)(struct acpi_battery *battery);

static struct acpi_read_mux {
	print_func print;
	get_func get;
} acpi_read_funcs[ACPI_BATTERY_NUMFILES] = {
	{.get = acpi_battery_get_info, .print = acpi_battery_print_info},
	{.get = acpi_battery_get_state, .print = acpi_battery_print_state},
	{.get = acpi_battery_get_alarm, .print = acpi_battery_print_alarm},
};

static int acpi_battery_read(int fid, struct seq_file *seq)
{
	struct acpi_battery *battery = seq->private;
	int result = 0;
	int update_result = ACPI_BATTERY_NONE_UPDATE;
	int update = 0;

	mutex_lock(&battery->mutex);

	update = (get_seconds() - battery->update_time[fid] >= update_time);
	update = (update | battery->flags.update[fid]);

	result = acpi_battery_update(battery, update, &update_result);
	if (result)
		goto end;

	if (update_result == ACPI_BATTERY_EASY_UPDATE) {
		result = acpi_read_funcs[fid].get(battery);
		if (result)
			goto end;
	}

      end:
	result = acpi_read_funcs[fid].print(seq, result);
	acpi_battery_check_result(battery, result);
	battery->flags.update[fid] = result;
	mutex_unlock(&battery->mutex);
	return result;
}

static int acpi_battery_read_info(struct seq_file *seq, void *offset)
{
	return acpi_battery_read(ACPI_BATTERY_INFO, seq);
}

static int acpi_battery_read_state(struct seq_file *seq, void *offset)
{
	return acpi_battery_read(ACPI_BATTERY_STATE, seq);
}

static int acpi_battery_read_alarm(struct seq_file *seq, void *offset)
{
	return acpi_battery_read(ACPI_BATTERY_ALARM, seq);
}

static int acpi_battery_info_open_fs(struct inode *inode, struct file *file)
{
	return single_open(file, acpi_battery_read_info, PDE(inode)->data);
}

static int acpi_battery_state_open_fs(struct inode *inode, struct file *file)
{
	return single_open(file, acpi_battery_read_state, PDE(inode)->data);
}

static int acpi_battery_alarm_open_fs(struct inode *inode, struct file *file)
{
	return single_open(file, acpi_battery_read_alarm, PDE(inode)->data);
}

static struct battery_file {
	struct file_operations ops;
	mode_t mode;
	char *name;
} acpi_battery_file[] = {
	{
	.name = "info",
	.mode = S_IRUGO,
	.ops = {
	.open = acpi_battery_info_open_fs,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
	.owner = THIS_MODULE,
	},
	},
	{
	.name = "state",
	.mode = S_IRUGO,
	.ops = {
	.open = acpi_battery_state_open_fs,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
	.owner = THIS_MODULE,
	},
	},
	{
	.name = "alarm",
	.mode = S_IFREG | S_IRUGO | S_IWUSR,
	.ops = {
	.open = acpi_battery_alarm_open_fs,
	.read = seq_read,
	.write = acpi_battery_write_alarm,
	.llseek = seq_lseek,
	.release = single_release,
	.owner = THIS_MODULE,
	},
	},
};

static int acpi_battery_add_fs(struct acpi_device *device)
{
	struct proc_dir_entry *entry = NULL;
	int i;

	if (!acpi_device_dir(device)) {
		acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device),
						     acpi_battery_dir);
		if (!acpi_device_dir(device))
			return -ENODEV;
		acpi_device_dir(device)->owner = THIS_MODULE;
	}

	for (i = 0; i < ACPI_BATTERY_NUMFILES; ++i) {
		entry = create_proc_entry(acpi_battery_file[i].name,
				  acpi_battery_file[i].mode, acpi_device_dir(device));
		if (!entry)
			return -ENODEV;
		else {
			entry->proc_fops = &acpi_battery_file[i].ops;
			entry->data = acpi_driver_data(device);
			entry->owner = THIS_MODULE;
		}
	}

	return 0;
}

static int acpi_battery_remove_fs(struct acpi_device *device)
{
	int i;
	if (acpi_device_dir(device)) {
		for (i = 0; i < ACPI_BATTERY_NUMFILES; ++i) {
			remove_proc_entry(acpi_battery_file[i].name,
				  acpi_device_dir(device));
		}
		remove_proc_entry(acpi_device_bid(device), acpi_battery_dir);
		acpi_device_dir(device) = NULL;
	}

	return 0;
}

/* --------------------------------------------------------------------------
                                 Driver Interface
   -------------------------------------------------------------------------- */

static void acpi_battery_notify(acpi_handle handle, u32 event, void *data)
{
	struct acpi_battery *battery = data;
	struct acpi_device *device = NULL;

	if (!battery)
		return;

	device = battery->device;

	switch (event) {
	case ACPI_BATTERY_NOTIFY_STATUS:
	case ACPI_BATTERY_NOTIFY_INFO:
	case ACPI_NOTIFY_BUS_CHECK:
	case ACPI_NOTIFY_DEVICE_CHECK:
		device = battery->device;
		acpi_battery_notify_update(battery);
		acpi_bus_generate_proc_event(device, event,
					acpi_battery_present(battery));
		acpi_bus_generate_netlink_event(device->pnp.device_class,
						  device->dev.bus_id, event,
						  acpi_battery_present(battery));
		break;
	default:
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "Unsupported event [0x%x]\n", event));
		break;
	}

	return;
}

static int acpi_battery_add(struct acpi_device *device)
{
	int result = 0;
	acpi_status status = 0;
	struct acpi_battery *battery = NULL;

	if (!device)
		return -EINVAL;

	battery = kzalloc(sizeof(struct acpi_battery), GFP_KERNEL);
	if (!battery)
		return -ENOMEM;

	mutex_init(&battery->mutex);

	mutex_lock(&battery->mutex);

	battery->device = device;
	strcpy(acpi_device_name(device), ACPI_BATTERY_DEVICE_NAME);
	strcpy(acpi_device_class(device), ACPI_BATTERY_CLASS);
	acpi_driver_data(device) = battery;

	result = acpi_battery_get_status(battery);
	if (result)
		goto end;

	battery->flags.init_update = 1;

	result = acpi_battery_add_fs(device);
	if (result)
		goto end;

	status = acpi_install_notify_handler(device->handle,
					     ACPI_ALL_NOTIFY,
					     acpi_battery_notify, battery);
	if (ACPI_FAILURE(status)) {
		ACPI_EXCEPTION((AE_INFO, status, "Installing notify handler"));
		result = -ENODEV;
		goto end;
	}

	printk(KERN_INFO PREFIX "%s Slot [%s] (battery %s)\n",
	       ACPI_BATTERY_DEVICE_NAME, acpi_device_bid(device),
	       device->status.battery_present ? "present" : "absent");

      end:

	if (result) {
		acpi_battery_remove_fs(device);
		kfree(battery);
	}

	mutex_unlock(&battery->mutex);

	return result;
}

static int acpi_battery_remove(struct acpi_device *device, int type)
{
	acpi_status status = 0;
	struct acpi_battery *battery = NULL;

	if (!device || !acpi_driver_data(device))
		return -EINVAL;

	battery = acpi_driver_data(device);

	mutex_lock(&battery->mutex);

	status = acpi_remove_notify_handler(device->handle,
					    ACPI_ALL_NOTIFY,
					    acpi_battery_notify);

	acpi_battery_remove_fs(device);

	kfree(battery->bif_data.pointer);

	kfree(battery->bst_data.pointer);

	mutex_unlock(&battery->mutex);

	mutex_destroy(&battery->mutex);

	kfree(battery);

	return 0;
}

/* this is needed to learn about changes made in suspended state */
static int acpi_battery_resume(struct acpi_device *device)
{
	struct acpi_battery *battery;

	if (!device)
		return -EINVAL;

	battery = device->driver_data;

	battery->flags.init_update = 1;

	return 0;
}

static int __init acpi_battery_init(void)
{
	int result;

	if (acpi_disabled)
		return -ENODEV;

	acpi_battery_dir = acpi_lock_battery_dir();
	if (!acpi_battery_dir)
		return -ENODEV;

	result = acpi_bus_register_driver(&acpi_battery_driver);
	if (result < 0) {
		acpi_unlock_battery_dir(acpi_battery_dir);
		return -ENODEV;
	}

	return 0;
}

static void __exit acpi_battery_exit(void)
{
	acpi_bus_unregister_driver(&acpi_battery_driver);

	acpi_unlock_battery_dir(acpi_battery_dir);

	return;
}

module_init(acpi_battery_init);
module_exit(acpi_battery_exit);