aboutsummaryrefslogtreecommitdiff
path: root/drivers/parisc/pdc_stable.c
blob: 0f54ab6260dfdcd719542e2a420db5b568b15ba4 (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
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
/* 
 *    Interfaces to retrieve and set PDC Stable options (firmware)
 *
 *    Copyright (C) 2005-2006 Thibaut VARENE <varenet@parisc-linux.org>
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License, version 2, as
 *    published by the Free Software Foundation.
 *
 *    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
 *
 *
 *    DEV NOTE: the PDC Procedures reference states that:
 *    "A minimum of 96 bytes of Stable Storage is required. Providing more than
 *    96 bytes of Stable Storage is optional [...]. Failure to provide the
 *    optional locations from 96 to 192 results in the loss of certain
 *    functionality during boot."
 *
 *    Since locations between 96 and 192 are the various paths, most (if not
 *    all) PA-RISC machines should have them. Anyway, for safety reasons, the
 *    following code can deal with just 96 bytes of Stable Storage, and all
 *    sizes between 96 and 192 bytes (provided they are multiple of struct
 *    device_path size, eg: 128, 160 and 192) to provide full information.
 *    One last word: there's one path we can always count on: the primary path.
 *    Anything above 224 bytes is used for 'osdep2' OS-dependent storage area.
 *
 *    The first OS-dependent area should always be available. Obviously, this is
 *    not true for the other one. Also bear in mind that reading/writing from/to
 *    osdep2 is much more expensive than from/to osdep1.
 *    NOTE: We do not handle the 2 bytes OS-dep area at 0x5D, nor the first
 *    2 bytes of storage available right after OSID. That's a total of 4 bytes
 *    sacrificed: -ETOOLAZY :P
 *
 *    The current policy wrt file permissions is:
 *	- write: root only
 *	- read: (reading triggers PDC calls) ? root only : everyone
 *    The rationale is that PDC calls could hog (DoS) the machine.
 *
 *	TODO:
 *	- timer/fastsize write calls
 */

#undef PDCS_DEBUG
#ifdef PDCS_DEBUG
#define DPRINTK(fmt, args...)	printk(KERN_DEBUG fmt, ## args)
#else
#define DPRINTK(fmt, args...)
#endif

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/capability.h>
#include <linux/ctype.h>
#include <linux/sysfs.h>
#include <linux/kobject.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/spinlock.h>

#include <asm/pdc.h>
#include <asm/page.h>
#include <asm/uaccess.h>
#include <asm/hardware.h>

#define PDCS_VERSION	"0.30"
#define PDCS_PREFIX	"PDC Stable Storage"

#define PDCS_ADDR_PPRI	0x00
#define PDCS_ADDR_OSID	0x40
#define PDCS_ADDR_OSD1	0x48
#define PDCS_ADDR_DIAG	0x58
#define PDCS_ADDR_FSIZ	0x5C
#define PDCS_ADDR_PCON	0x60
#define PDCS_ADDR_PALT	0x80
#define PDCS_ADDR_PKBD	0xA0
#define PDCS_ADDR_OSD2	0xE0

MODULE_AUTHOR("Thibaut VARENE <varenet@parisc-linux.org>");
MODULE_DESCRIPTION("sysfs interface to HP PDC Stable Storage data");
MODULE_LICENSE("GPL");
MODULE_VERSION(PDCS_VERSION);

/* holds Stable Storage size. Initialized once and for all, no lock needed */
static unsigned long pdcs_size __read_mostly;

/* holds OS ID. Initialized once and for all, hopefully to 0x0006 */
static u16 pdcs_osid __read_mostly;

/* This struct defines what we need to deal with a parisc pdc path entry */
struct pdcspath_entry {
	rwlock_t rw_lock;		/* to protect path entry access */
	short ready;			/* entry record is valid if != 0 */
	unsigned long addr;		/* entry address in stable storage */
	char *name;			/* entry name */
	struct device_path devpath;	/* device path in parisc representation */
	struct device *dev;		/* corresponding device */
	struct kobject kobj;
};

struct pdcspath_attribute {
	struct attribute attr;
	ssize_t (*show)(struct pdcspath_entry *entry, char *buf);
	ssize_t (*store)(struct pdcspath_entry *entry, const char *buf, size_t count);
};

#define PDCSPATH_ENTRY(_addr, _name) \
struct pdcspath_entry pdcspath_entry_##_name = { \
	.ready = 0, \
	.addr = _addr, \
	.name = __stringify(_name), \
};

#define PDCS_ATTR(_name, _mode, _show, _store) \
struct kobj_attribute pdcs_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode}, \
	.show = _show, \
	.store = _store, \
};

#define PATHS_ATTR(_name, _mode, _show, _store) \
struct pdcspath_attribute paths_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode}, \
	.show = _show, \
	.store = _store, \
};

#define to_pdcspath_attribute(_attr) container_of(_attr, struct pdcspath_attribute, attr)
#define to_pdcspath_entry(obj)  container_of(obj, struct pdcspath_entry, kobj)

/**
 * pdcspath_fetch - This function populates the path entry structs.
 * @entry: A pointer to an allocated pdcspath_entry.
 * 
 * The general idea is that you don't read from the Stable Storage every time
 * you access the files provided by the facilities. We store a copy of the
 * content of the stable storage WRT various paths in these structs. We read
 * these structs when reading the files, and we will write to these structs when
 * writing to the files, and only then write them back to the Stable Storage.
 *
 * This function expects to be called with @entry->rw_lock write-hold.
 */
static int
pdcspath_fetch(struct pdcspath_entry *entry)
{
	struct device_path *devpath;

	if (!entry)
		return -EINVAL;

	devpath = &entry->devpath;
	
	DPRINTK("%s: fetch: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
			entry, devpath, entry->addr);

	/* addr, devpath and count must be word aligned */
	if (pdc_stable_read(entry->addr, devpath, sizeof(*devpath)) != PDC_OK)
		return -EIO;
		
	/* Find the matching device.
	   NOTE: hardware_path overlays with device_path, so the nice cast can
	   be used */
	entry->dev = hwpath_to_device((struct hardware_path *)devpath);

	entry->ready = 1;
	
	DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
	
	return 0;
}

/**
 * pdcspath_store - This function writes a path to stable storage.
 * @entry: A pointer to an allocated pdcspath_entry.
 * 
 * It can be used in two ways: either by passing it a preset devpath struct
 * containing an already computed hardware path, or by passing it a device
 * pointer, from which it'll find out the corresponding hardware path.
 * For now we do not handle the case where there's an error in writing to the
 * Stable Storage area, so you'd better not mess up the data :P
 *
 * This function expects to be called with @entry->rw_lock write-hold.
 */
static void
pdcspath_store(struct pdcspath_entry *entry)
{
	struct device_path *devpath;

	BUG_ON(!entry);

	devpath = &entry->devpath;
	
	/* We expect the caller to set the ready flag to 0 if the hardware
	   path struct provided is invalid, so that we know we have to fill it.
	   First case, we don't have a preset hwpath... */
	if (!entry->ready) {
		/* ...but we have a device, map it */
		BUG_ON(!entry->dev);
		device_to_hwpath(entry->dev, (struct hardware_path *)devpath);
	}
	/* else, we expect the provided hwpath to be valid. */
	
	DPRINTK("%s: store: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
			entry, devpath, entry->addr);

	/* addr, devpath and count must be word aligned */
	if (pdc_stable_write(entry->addr, devpath, sizeof(*devpath)) != PDC_OK)
		WARN(1, KERN_ERR "%s: an error occurred when writing to PDC.\n"
				"It is likely that the Stable Storage data has been corrupted.\n"
				"Please check it carefully upon next reboot.\n", __func__);
		
	/* kobject is already registered */
	entry->ready = 2;
	
	DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
}

/**
 * pdcspath_hwpath_read - This function handles hardware path pretty printing.
 * @entry: An allocated and populated pdscpath_entry struct.
 * @buf: The output buffer to write to.
 * 
 * We will call this function to format the output of the hwpath attribute file.
 */
static ssize_t
pdcspath_hwpath_read(struct pdcspath_entry *entry, char *buf)
{
	char *out = buf;
	struct device_path *devpath;
	short i;

	if (!entry || !buf)
		return -EINVAL;

	read_lock(&entry->rw_lock);
	devpath = &entry->devpath;
	i = entry->ready;
	read_unlock(&entry->rw_lock);

	if (!i)	/* entry is not ready */
		return -ENODATA;
	
	for (i = 0; i < 6; i++) {
		if (devpath->bc[i] >= 128)
			continue;
		out += sprintf(out, "%u/", (unsigned char)devpath->bc[i]);
	}
	out += sprintf(out, "%u\n", (unsigned char)devpath->mod);
	
	return out - buf;
}

/**
 * pdcspath_hwpath_write - This function handles hardware path modifying.
 * @entry: An allocated and populated pdscpath_entry struct.
 * @buf: The input buffer to read from.
 * @count: The number of bytes to be read.
 * 
 * We will call this function to change the current hardware path.
 * Hardware paths are to be given '/'-delimited, without brackets.
 * We make sure that the provided path actually maps to an existing
 * device, BUT nothing would prevent some foolish user to set the path to some
 * PCI bridge or even a CPU...
 * A better work around would be to make sure we are at the end of a device tree
 * for instance, but it would be IMHO beyond the simple scope of that driver.
 * The aim is to provide a facility. Data correctness is left to userland.
 */
static ssize_t
pdcspath_hwpath_write(struct pdcspath_entry *entry, const char *buf, size_t count)
{
	struct hardware_path hwpath;
	unsigned short i;
	char in[count+1], *temp;
	struct device *dev;
	int ret;

	if (!entry || !buf || !count)
		return -EINVAL;

	/* We'll use a local copy of buf */
	memset(in, 0, count+1);
	strncpy(in, buf, count);
	
	/* Let's clean up the target. 0xff is a blank pattern */
	memset(&hwpath, 0xff, sizeof(hwpath));
	
	/* First, pick the mod field (the last one of the input string) */
	if (!(temp = strrchr(in, '/')))
		return -EINVAL;
			
	hwpath.mod = simple_strtoul(temp+1, NULL, 10);
	in[temp-in] = '\0';	/* truncate the remaining string. just precaution */
	DPRINTK("%s: mod: %d\n", __func__, hwpath.mod);
	
	/* Then, loop for each delimiter, making sure we don't have too many.
	   we write the bc fields in a down-top way. No matter what, we stop
	   before writing the last field. If there are too many fields anyway,
	   then the user is a moron and it'll be caught up later when we'll
	   check the consistency of the given hwpath. */
	for (i=5; ((temp = strrchr(in, '/'))) && (temp-in > 0) && (likely(i)); i--) {
		hwpath.bc[i] = simple_strtoul(temp+1, NULL, 10);
		in[temp-in] = '\0';
		DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.bc[i]);
	}
	
	/* Store the final field */		
	hwpath.bc[i] = simple_strtoul(in, NULL, 10);
	DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.bc[i]);
	
	/* Now we check that the user isn't trying to lure us */
	if (!(dev = hwpath_to_device((struct hardware_path *)&hwpath))) {
		printk(KERN_WARNING "%s: attempt to set invalid \"%s\" "
			"hardware path: %s\n", __func__, entry->name, buf);
		return -EINVAL;
	}
	
	/* So far so good, let's get in deep */
	write_lock(&entry->rw_lock);
	entry->ready = 0;
	entry->dev = dev;
	
	/* Now, dive in. Write back to the hardware */
	pdcspath_store(entry);
	
	/* Update the symlink to the real device */
	sysfs_remove_link(&entry->kobj, "device");
	ret = sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
	WARN_ON(ret);

	write_unlock(&entry->rw_lock);
	
	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" path to \"%s\"\n",
		entry->name, buf);
	
	return count;
}

/**
 * pdcspath_layer_read - Extended layer (eg. SCSI ids) pretty printing.
 * @entry: An allocated and populated pdscpath_entry struct.
 * @buf: The output buffer to write to.
 * 
 * We will call this function to format the output of the layer attribute file.
 */
static ssize_t
pdcspath_layer_read(struct pdcspath_entry *entry, char *buf)
{
	char *out = buf;
	struct device_path *devpath;
	short i;

	if (!entry || !buf)
		return -EINVAL;
	
	read_lock(&entry->rw_lock);
	devpath = &entry->devpath;
	i = entry->ready;
	read_unlock(&entry->rw_lock);

	if (!i)	/* entry is not ready */
		return -ENODATA;
	
	for (i = 0; i < 6 && devpath->layers[i]; i++)
		out += sprintf(out, "%u ", devpath->layers[i]);

	out += sprintf(out, "\n");
	
	return out - buf;
}

/**
 * pdcspath_layer_write - This function handles extended layer modifying.
 * @entry: An allocated and populated pdscpath_entry struct.
 * @buf: The input buffer to read from.
 * @count: The number of bytes to be read.
 * 
 * We will call this function to change the current layer value.
 * Layers are to be given '.'-delimited, without brackets.
 * XXX beware we are far less checky WRT input data provided than for hwpath.
 * Potential harm can be done, since there's no way to check the validity of
 * the layer fields.
 */
static ssize_t
pdcspath_layer_write(struct pdcspath_entry *entry, const char *buf, size_t count)
{
	unsigned int layers[6]; /* device-specific info (ctlr#, unit#, ...) */
	unsigned short i;
	char in[count+1], *temp;

	if (!entry || !buf || !count)
		return -EINVAL;

	/* We'll use a local copy of buf */
	memset(in, 0, count+1);
	strncpy(in, buf, count);
	
	/* Let's clean up the target. 0 is a blank pattern */
	memset(&layers, 0, sizeof(layers));
	
	/* First, pick the first layer */
	if (unlikely(!isdigit(*in)))
		return -EINVAL;
	layers[0] = simple_strtoul(in, NULL, 10);
	DPRINTK("%s: layer[0]: %d\n", __func__, layers[0]);
	
	temp = in;
	for (i=1; ((temp = strchr(temp, '.'))) && (likely(i<6)); i++) {
		if (unlikely(!isdigit(*(++temp))))
			return -EINVAL;
		layers[i] = simple_strtoul(temp, NULL, 10);
		DPRINTK("%s: layer[%d]: %d\n", __func__, i, layers[i]);
	}
		
	/* So far so good, let's get in deep */
	write_lock(&entry->rw_lock);
	
	/* First, overwrite the current layers with the new ones, not touching
	   the hardware path. */
	memcpy(&entry->devpath.layers, &layers, sizeof(layers));
	
	/* Now, dive in. Write back to the hardware */
	pdcspath_store(entry);
	write_unlock(&entry->rw_lock);
	
	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" layers to \"%s\"\n",
		entry->name, buf);
	
	return count;
}

/**
 * pdcspath_attr_show - Generic read function call wrapper.
 * @kobj: The kobject to get info from.
 * @attr: The attribute looked upon.
 * @buf: The output buffer.
 */
static ssize_t
pdcspath_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
{
	struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
	struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
	ssize_t ret = 0;

	if (pdcs_attr->show)
		ret = pdcs_attr->show(entry, buf);

	return ret;
}

/**
 * pdcspath_attr_store - Generic write function call wrapper.
 * @kobj: The kobject to write info to.
 * @attr: The attribute to be modified.
 * @buf: The input buffer.
 * @count: The size of the buffer.
 */
static ssize_t
pdcspath_attr_store(struct kobject *kobj, struct attribute *attr,
			const char *buf, size_t count)
{
	struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
	struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
	ssize_t ret = 0;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (pdcs_attr->store)
		ret = pdcs_attr->store(entry, buf, count);

	return ret;
}

static const struct sysfs_ops pdcspath_attr_ops = {
	.show = pdcspath_attr_show,
	.store = pdcspath_attr_store,
};

/* These are the two attributes of any PDC path. */
static PATHS_ATTR(hwpath, 0644, pdcspath_hwpath_read, pdcspath_hwpath_write);
static PATHS_ATTR(layer, 0644, pdcspath_layer_read, pdcspath_layer_write);

static struct attribute *paths_subsys_attrs[] = {
	&paths_attr_hwpath.attr,
	&paths_attr_layer.attr,
	NULL,
};

/* Specific kobject type for our PDC paths */
static struct kobj_type ktype_pdcspath = {
	.sysfs_ops = &pdcspath_attr_ops,
	.default_attrs = paths_subsys_attrs,
};

/* We hard define the 4 types of path we expect to find */
static PDCSPATH_ENTRY(PDCS_ADDR_PPRI, primary);
static PDCSPATH_ENTRY(PDCS_ADDR_PCON, console);
static PDCSPATH_ENTRY(PDCS_ADDR_PALT, alternative);
static PDCSPATH_ENTRY(PDCS_ADDR_PKBD, keyboard);

/* An array containing all PDC paths we will deal with */
static struct pdcspath_entry *pdcspath_entries[] = {
	&pdcspath_entry_primary,
	&pdcspath_entry_alternative,
	&pdcspath_entry_console,
	&pdcspath_entry_keyboard,
	NULL,
};


/* For more insight of what's going on here, refer to PDC Procedures doc,
 * Section PDC_STABLE */

/**
 * pdcs_size_read - Stable Storage size output.
 * @buf: The output buffer to write to.
 */
static ssize_t pdcs_size_read(struct kobject *kobj,
			      struct kobj_attribute *attr,
			      char *buf)
{
	char *out = buf;

	if (!buf)
		return -EINVAL;

	/* show the size of the stable storage */
	out += sprintf(out, "%ld\n", pdcs_size);

	return out - buf;
}

/**
 * pdcs_auto_read - Stable Storage autoboot/search flag output.
 * @buf: The output buffer to write to.
 * @knob: The PF_AUTOBOOT or PF_AUTOSEARCH flag
 */
static ssize_t pdcs_auto_read(struct kobject *kobj,
			      struct kobj_attribute *attr,
			      char *buf, int knob)
{
	char *out = buf;
	struct pdcspath_entry *pathentry;

	if (!buf)
		return -EINVAL;

	/* Current flags are stored in primary boot path entry */
	pathentry = &pdcspath_entry_primary;

	read_lock(&pathentry->rw_lock);
	out += sprintf(out, "%s\n", (pathentry->devpath.flags & knob) ?
					"On" : "Off");
	read_unlock(&pathentry->rw_lock);

	return out - buf;
}

/**
 * pdcs_autoboot_read - Stable Storage autoboot flag output.
 * @buf: The output buffer to write to.
 */
static ssize_t pdcs_autoboot_read(struct kobject *kobj,
				  struct kobj_attribute *attr, char *buf)
{
	return pdcs_auto_read(kobj, attr, buf, PF_AUTOBOOT);
}

/**
 * pdcs_autosearch_read - Stable Storage autoboot flag output.
 * @buf: The output buffer to write to.
 */
static ssize_t pdcs_autosearch_read(struct kobject *kobj,
				    struct kobj_attribute *attr, char *buf)
{
	return pdcs_auto_read(kobj, attr, buf, PF_AUTOSEARCH);
}

/**
 * pdcs_timer_read - Stable Storage timer count output (in seconds).
 * @buf: The output buffer to write to.
 *
 * The value of the timer field correponds to a number of seconds in powers of 2.
 */
static ssize_t pdcs_timer_read(struct kobject *kobj,
			       struct kobj_attribute *attr, char *buf)
{
	char *out = buf;
	struct pdcspath_entry *pathentry;

	if (!buf)
		return -EINVAL;

	/* Current flags are stored in primary boot path entry */
	pathentry = &pdcspath_entry_primary;

	/* print the timer value in seconds */
	read_lock(&pathentry->rw_lock);
	out += sprintf(out, "%u\n", (pathentry->devpath.flags & PF_TIMER) ?
				(1 << (pathentry->devpath.flags & PF_TIMER)) : 0);
	read_unlock(&pathentry->rw_lock);

	return out - buf;
}

/**
 * pdcs_osid_read - Stable Storage OS ID register output.
 * @buf: The output buffer to write to.
 */
static ssize_t pdcs_osid_read(struct kobject *kobj,
			      struct kobj_attribute *attr, char *buf)
{
	char *out = buf;

	if (!buf)
		return -EINVAL;

	out += sprintf(out, "%s dependent data (0x%.4x)\n",
		os_id_to_string(pdcs_osid), pdcs_osid);

	return out - buf;
}

/**
 * pdcs_osdep1_read - Stable Storage OS-Dependent data area 1 output.
 * @buf: The output buffer to write to.
 *
 * This can hold 16 bytes of OS-Dependent data.
 */
static ssize_t pdcs_osdep1_read(struct kobject *kobj,
				struct kobj_attribute *attr, char *buf)
{
	char *out = buf;
	u32 result[4];

	if (!buf)
		return -EINVAL;

	if (pdc_stable_read(PDCS_ADDR_OSD1, &result, sizeof(result)) != PDC_OK)
		return -EIO;

	out += sprintf(out, "0x%.8x\n", result[0]);
	out += sprintf(out, "0x%.8x\n", result[1]);
	out += sprintf(out, "0x%.8x\n", result[2]);
	out += sprintf(out, "0x%.8x\n", result[3]);

	return out - buf;
}

/**
 * pdcs_diagnostic_read - Stable Storage Diagnostic register output.
 * @buf: The output buffer to write to.
 *
 * I have NFC how to interpret the content of that register ;-).
 */
static ssize_t pdcs_diagnostic_read(struct kobject *kobj,
				    struct kobj_attribute *attr, char *buf)
{
	char *out = buf;
	u32 result;

	if (!buf)
		return -EINVAL;

	/* get diagnostic */
	if (pdc_stable_read(PDCS_ADDR_DIAG, &result, sizeof(result)) != PDC_OK)
		return -EIO;

	out += sprintf(out, "0x%.4x\n", (result >> 16));

	return out - buf;
}

/**
 * pdcs_fastsize_read - Stable Storage FastSize register output.
 * @buf: The output buffer to write to.
 *
 * This register holds the amount of system RAM to be tested during boot sequence.
 */
static ssize_t pdcs_fastsize_read(struct kobject *kobj,
				  struct kobj_attribute *attr, char *buf)
{
	char *out = buf;
	u32 result;

	if (!buf)
		return -EINVAL;

	/* get fast-size */
	if (pdc_stable_read(PDCS_ADDR_FSIZ, &result, sizeof(result)) != PDC_OK)
		return -EIO;

	if ((result & 0x0F) < 0x0E)
		out += sprintf(out, "%d kB", (1<<(result & 0x0F))*256);
	else
		out += sprintf(out, "All");
	out += sprintf(out, "\n");
	
	return out - buf;
}

/**
 * pdcs_osdep2_read - Stable Storage OS-Dependent data area 2 output.
 * @buf: The output buffer to write to.
 *
 * This can hold pdcs_size - 224 bytes of OS-Dependent data, when available.
 */
static ssize_t pdcs_osdep2_read(struct kobject *kobj,
				struct kobj_attribute *attr, char *buf)
{
	char *out = buf;
	unsigned long size;
	unsigned short i;
	u32 result;

	if (unlikely(pdcs_size <= 224))
		return -ENODATA;

	size = pdcs_size - 224;

	if (!buf)
		return -EINVAL;

	for (i=0; i<size; i+=4) {
		if (unlikely(pdc_stable_read(PDCS_ADDR_OSD2 + i, &result,
					sizeof(result)) != PDC_OK))
			return -EIO;
		out += sprintf(out, "0x%.8x\n", result);
	}

	return out - buf;
}

/**
 * pdcs_auto_write - This function handles autoboot/search flag modifying.
 * @buf: The input buffer to read from.
 * @count: The number of bytes to be read.
 * @knob: The PF_AUTOBOOT or PF_AUTOSEARCH flag
 * 
 * We will call this function to change the current autoboot flag.
 * We expect a precise syntax:
 *	\"n\" (n == 0 or 1) to toggle AutoBoot Off or On
 */
static ssize_t pdcs_auto_write(struct kobject *kobj,
			       struct kobj_attribute *attr, const char *buf,
			       size_t count, int knob)
{
	struct pdcspath_entry *pathentry;
	unsigned char flags;
	char in[count+1], *temp;
	char c;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (!buf || !count)
		return -EINVAL;

	/* We'll use a local copy of buf */
	memset(in, 0, count+1);
	strncpy(in, buf, count);

	/* Current flags are stored in primary boot path entry */
	pathentry = &pdcspath_entry_primary;
	
	/* Be nice to the existing flag record */
	read_lock(&pathentry->rw_lock);
	flags = pathentry->devpath.flags;
	read_unlock(&pathentry->rw_lock);
	
	DPRINTK("%s: flags before: 0x%X\n", __func__, flags);

	temp = skip_spaces(in);

	c = *temp++ - '0';
	if ((c != 0) && (c != 1))
		goto parse_error;
	if (c == 0)
		flags &= ~knob;
	else
		flags |= knob;
	
	DPRINTK("%s: flags after: 0x%X\n", __func__, flags);
		
	/* So far so good, let's get in deep */
	write_lock(&pathentry->rw_lock);
	
	/* Change the path entry flags first */
	pathentry->devpath.flags = flags;
		
	/* Now, dive in. Write back to the hardware */
	pdcspath_store(pathentry);
	write_unlock(&pathentry->rw_lock);
	
	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" to \"%s\"\n",
		(knob & PF_AUTOBOOT) ? "autoboot" : "autosearch",
		(flags & knob) ? "On" : "Off");
	
	return count;

parse_error:
	printk(KERN_WARNING "%s: Parse error: expect \"n\" (n == 0 or 1)\n", __func__);
	return -EINVAL;
}

/**
 * pdcs_autoboot_write - This function handles autoboot flag modifying.
 * @buf: The input buffer to read from.
 * @count: The number of bytes to be read.
 *
 * We will call this function to change the current boot flags.
 * We expect a precise syntax:
 *	\"n\" (n == 0 or 1) to toggle AutoSearch Off or On
 */
static ssize_t pdcs_autoboot_write(struct kobject *kobj,
				   struct kobj_attribute *attr,
				   const char *buf, size_t count)
{
	return pdcs_auto_write(kobj, attr, buf, count, PF_AUTOBOOT);
}

/**
 * pdcs_autosearch_write - This function handles autosearch flag modifying.
 * @buf: The input buffer to read from.
 * @count: The number of bytes to be read.
 *
 * We will call this function to change the current boot flags.
 * We expect a precise syntax:
 *	\"n\" (n == 0 or 1) to toggle AutoSearch Off or On
 */
static ssize_t pdcs_autosearch_write(struct kobject *kobj,
				     struct kobj_attribute *attr,
				     const char *buf, size_t count)
{
	return pdcs_auto_write(kobj, attr, buf, count, PF_AUTOSEARCH);
}

/**
 * pdcs_osdep1_write - Stable Storage OS-Dependent data area 1 input.
 * @buf: The input buffer to read from.
 * @count: The number of bytes to be read.
 *
 * This can store 16 bytes of OS-Dependent data. We use a byte-by-byte
 * write approach. It's up to userspace to deal with it when constructing
 * its input buffer.
 */
static ssize_t pdcs_osdep1_write(struct kobject *kobj,
				 struct kobj_attribute *attr,
				 const char *buf, size_t count)
{
	u8 in[16];

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (!buf || !count)
		return -EINVAL;

	if (unlikely(pdcs_osid != OS_ID_LINUX))
		return -EPERM;

	if (count > 16)
		return -EMSGSIZE;

	/* We'll use a local copy of buf */
	memset(in, 0, 16);
	memcpy(in, buf, count);

	if (pdc_stable_write(PDCS_ADDR_OSD1, &in, sizeof(in)) != PDC_OK)
		return -EIO;

	return count;
}

/**
 * pdcs_osdep2_write - Stable Storage OS-Dependent data area 2 input.
 * @buf: The input buffer to read from.
 * @count: The number of bytes to be read.
 *
 * This can store pdcs_size - 224 bytes of OS-Dependent data. We use a
 * byte-by-byte write approach. It's up to userspace to deal with it when
 * constructing its input buffer.
 */
static ssize_t pdcs_osdep2_write(struct kobject *kobj,
				 struct kobj_attribute *attr,
				 const char *buf, size_t count)
{
	unsigned long size;
	unsigned short i;
	u8 in[4];

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (!buf || !count)
		return -EINVAL;

	if (unlikely(pdcs_size <= 224))
		return -ENOSYS;

	if (unlikely(pdcs_osid != OS_ID_LINUX))
		return -EPERM;

	size = pdcs_size - 224;

	if (count > size)
		return -EMSGSIZE;

	/* We'll use a local copy of buf */

	for (i=0; i<count; i+=4) {
		memset(in, 0, 4);
		memcpy(in, buf+i, (count-i < 4) ? count-i : 4);
		if (unlikely(pdc_stable_write(PDCS_ADDR_OSD2 + i, &in,
					sizeof(in)) != PDC_OK))
			return -EIO;
	}

	return count;
}

/* The remaining attributes. */
static PDCS_ATTR(size, 0444, pdcs_size_read, NULL);
static PDCS_ATTR(autoboot, 0644, pdcs_autoboot_read, pdcs_autoboot_write);
static PDCS_ATTR(autosearch, 0644, pdcs_autosearch_read, pdcs_autosearch_write);
static PDCS_ATTR(timer, 0444, pdcs_timer_read, NULL);
static PDCS_ATTR(osid, 0444, pdcs_osid_read, NULL);
static PDCS_ATTR(osdep1, 0600, pdcs_osdep1_read, pdcs_osdep1_write);
static PDCS_ATTR(diagnostic, 0400, pdcs_diagnostic_read, NULL);
static PDCS_ATTR(fastsize, 0400, pdcs_fastsize_read, NULL);
static PDCS_ATTR(osdep2, 0600, pdcs_osdep2_read, pdcs_osdep2_write);

static struct attribute *pdcs_subsys_attrs[] = {
	&pdcs_attr_size.attr,
	&pdcs_attr_autoboot.attr,
	&pdcs_attr_autosearch.attr,
	&pdcs_attr_timer.attr,
	&pdcs_attr_osid.attr,
	&pdcs_attr_osdep1.attr,
	&pdcs_attr_diagnostic.attr,
	&pdcs_attr_fastsize.attr,
	&pdcs_attr_osdep2.attr,
	NULL,
};

static struct attribute_group pdcs_attr_group = {
	.attrs = pdcs_subsys_attrs,
};

static struct kobject *stable_kobj;
static struct kset *paths_kset;

/**
 * pdcs_register_pathentries - Prepares path entries kobjects for sysfs usage.
 * 
 * It creates kobjects corresponding to each path entry with nice sysfs
 * links to the real device. This is where the magic takes place: when
 * registering the subsystem attributes during module init, each kobject hereby
 * created will show in the sysfs tree as a folder containing files as defined
 * by path_subsys_attr[].
 */
static inline int __init
pdcs_register_pathentries(void)
{
	unsigned short i;
	struct pdcspath_entry *entry;
	int err;
	
	/* Initialize the entries rw_lock before anything else */
	for (i = 0; (entry = pdcspath_entries[i]); i++)
		rwlock_init(&entry->rw_lock);

	for (i = 0; (entry = pdcspath_entries[i]); i++) {
		write_lock(&entry->rw_lock);
		err = pdcspath_fetch(entry);
		write_unlock(&entry->rw_lock);

		if (err < 0)
			continue;

		entry->kobj.kset = paths_kset;
		err = kobject_init_and_add(&entry->kobj, &ktype_pdcspath, NULL,
					   "%s", entry->name);
		if (err)
			return err;

		/* kobject is now registered */
		write_lock(&entry->rw_lock);
		entry->ready = 2;
		
		/* Add a nice symlink to the real device */
		if (entry->dev) {
			err = sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
			WARN_ON(err);
		}

		write_unlock(&entry->rw_lock);
		kobject_uevent(&entry->kobj, KOBJ_ADD);
	}
	
	return 0;
}

/**
 * pdcs_unregister_pathentries - Routine called when unregistering the module.
 */
static inline void
pdcs_unregister_pathentries(void)
{
	unsigned short i;
	struct pdcspath_entry *entry;
	
	for (i = 0; (entry = pdcspath_entries[i]); i++) {
		read_lock(&entry->rw_lock);
		if (entry->ready >= 2)
			kobject_put(&entry->kobj);
		read_unlock(&entry->rw_lock);
	}
}

/*
 * For now we register the stable subsystem with the firmware subsystem
 * and the paths subsystem with the stable subsystem
 */
static int __init
pdc_stable_init(void)
{
	int rc = 0, error = 0;
	u32 result;

	/* find the size of the stable storage */
	if (pdc_stable_get_size(&pdcs_size) != PDC_OK) 
		return -ENODEV;

	/* make sure we have enough data */
	if (pdcs_size < 96)
		return -ENODATA;

	printk(KERN_INFO PDCS_PREFIX " facility v%s\n", PDCS_VERSION);

	/* get OSID */
	if (pdc_stable_read(PDCS_ADDR_OSID, &result, sizeof(result)) != PDC_OK)
		return -EIO;

	/* the actual result is 16 bits away */
	pdcs_osid = (u16)(result >> 16);

	/* For now we'll register the directory at /sys/firmware/stable */
	stable_kobj = kobject_create_and_add("stable", firmware_kobj);
	if (!stable_kobj) {
		rc = -ENOMEM;
		goto fail_firmreg;
	}

	/* Don't forget the root entries */
	error = sysfs_create_group(stable_kobj, &pdcs_attr_group);

	/* register the paths kset as a child of the stable kset */
	paths_kset = kset_create_and_add("paths", NULL, stable_kobj);
	if (!paths_kset) {
		rc = -ENOMEM;
		goto fail_ksetreg;
	}

	/* now we create all "files" for the paths kset */
	if ((rc = pdcs_register_pathentries()))
		goto fail_pdcsreg;

	return rc;
	
fail_pdcsreg:
	pdcs_unregister_pathentries();
	kset_unregister(paths_kset);
	
fail_ksetreg:
	kobject_put(stable_kobj);
	
fail_firmreg:
	printk(KERN_INFO PDCS_PREFIX " bailing out\n");
	return rc;
}

static void __exit
pdc_stable_exit(void)
{
	pdcs_unregister_pathentries();
	kset_unregister(paths_kset);
	kobject_put(stable_kobj);
}


module_init(pdc_stable_init);
module_exit(pdc_stable_exit);