summaryrefslogtreecommitdiff
path: root/drivers/gpu/vga/vgaarb.c
blob: 0f5b2dd245075830a3796e98256409a3152bab73 (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
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
/*
 * vgaarb.c: Implements the VGA arbitration. For details refer to
 * Documentation/vgaarbiter.txt
 *
 *
 * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
 * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
 * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS
 * IN THE SOFTWARE.
 *
 */

#define pr_fmt(fmt) "vgaarb: " fmt

#define vgaarb_dbg(dev, fmt, arg...)	dev_dbg(dev, "vgaarb: " fmt, ##arg)
#define vgaarb_info(dev, fmt, arg...)	dev_info(dev, "vgaarb: " fmt, ##arg)
#define vgaarb_err(dev, fmt, arg...)	dev_err(dev, "vgaarb: " fmt, ##arg)

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <linux/poll.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/screen_info.h>

#include <linux/uaccess.h>

#include <linux/vgaarb.h>

static void vga_arbiter_notify_clients(void);
/*
 * We keep a list of all vga devices in the system to speed
 * up the various operations of the arbiter
 */
struct vga_device {
	struct list_head list;
	struct pci_dev *pdev;
	unsigned int decodes;	/* what does it decodes */
	unsigned int owns;	/* what does it owns */
	unsigned int locks;	/* what does it locks */
	unsigned int io_lock_cnt;	/* legacy IO lock count */
	unsigned int mem_lock_cnt;	/* legacy MEM lock count */
	unsigned int io_norm_cnt;	/* normal IO count */
	unsigned int mem_norm_cnt;	/* normal MEM count */
	bool bridge_has_one_vga;
	/* allow IRQ enable/disable hook */
	void *cookie;
	void (*irq_set_state)(void *cookie, bool enable);
	unsigned int (*set_vga_decode)(void *cookie, bool decode);
};

static LIST_HEAD(vga_list);
static int vga_count, vga_decode_count;
static bool vga_arbiter_used;
static DEFINE_SPINLOCK(vga_lock);
static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);


static const char *vga_iostate_to_str(unsigned int iostate)
{
	/* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
	iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
	switch (iostate) {
	case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
		return "io+mem";
	case VGA_RSRC_LEGACY_IO:
		return "io";
	case VGA_RSRC_LEGACY_MEM:
		return "mem";
	}
	return "none";
}

static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
{
	/* we could in theory hand out locks on IO and mem
	 * separately to userspace but it can cause deadlocks */
	if (strncmp(buf, "none", 4) == 0) {
		*io_state = VGA_RSRC_NONE;
		return 1;
	}

	/* XXX We're not chekcing the str_size! */
	if (strncmp(buf, "io+mem", 6) == 0)
		goto both;
	else if (strncmp(buf, "io", 2) == 0)
		goto both;
	else if (strncmp(buf, "mem", 3) == 0)
		goto both;
	return 0;
both:
	*io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
	return 1;
}

/* this is only used a cookie - it should not be dereferenced */
static struct pci_dev *vga_default;

static void vga_arb_device_card_gone(struct pci_dev *pdev);

/* Find somebody in our list */
static struct vga_device *vgadev_find(struct pci_dev *pdev)
{
	struct vga_device *vgadev;

	list_for_each_entry(vgadev, &vga_list, list)
		if (pdev == vgadev->pdev)
			return vgadev;
	return NULL;
}

/**
 * vga_default_device - return the default VGA device, for vgacon
 *
 * This can be defined by the platform. The default implementation
 * is rather dumb and will probably only work properly on single
 * vga card setups and/or x86 platforms.
 *
 * If your VGA default device is not PCI, you'll have to return
 * NULL here. In this case, I assume it will not conflict with
 * any PCI card. If this is not true, I'll have to define two archs
 * hooks for enabling/disabling the VGA default device if that is
 * possible. This may be a problem with real _ISA_ VGA cards, in
 * addition to a PCI one. I don't know at this point how to deal
 * with that card. Can theirs IOs be disabled at all ? If not, then
 * I suppose it's a matter of having the proper arch hook telling
 * us about it, so we basically never allow anybody to succeed a
 * vga_get()...
 */
struct pci_dev *vga_default_device(void)
{
	return vga_default;
}
EXPORT_SYMBOL_GPL(vga_default_device);

void vga_set_default_device(struct pci_dev *pdev)
{
	if (vga_default == pdev)
		return;

	pci_dev_put(vga_default);
	vga_default = pci_dev_get(pdev);
}

static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
{
	if (vgadev->irq_set_state)
		vgadev->irq_set_state(vgadev->cookie, state);
}


/* If we don't ever use VGA arb we should avoid
   turning off anything anywhere due to old X servers getting
   confused about the boot device not being VGA */
static void vga_check_first_use(void)
{
	/* we should inform all GPUs in the system that
	 * VGA arb has occurred and to try and disable resources
	 * if they can */
	if (!vga_arbiter_used) {
		vga_arbiter_used = true;
		vga_arbiter_notify_clients();
	}
}

static struct vga_device *__vga_tryget(struct vga_device *vgadev,
				       unsigned int rsrc)
{
	struct device *dev = &vgadev->pdev->dev;
	unsigned int wants, legacy_wants, match;
	struct vga_device *conflict;
	unsigned int pci_bits;
	u32 flags = 0;

	/* Account for "normal" resources to lock. If we decode the legacy,
	 * counterpart, we need to request it as well
	 */
	if ((rsrc & VGA_RSRC_NORMAL_IO) &&
	    (vgadev->decodes & VGA_RSRC_LEGACY_IO))
		rsrc |= VGA_RSRC_LEGACY_IO;
	if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
	    (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
		rsrc |= VGA_RSRC_LEGACY_MEM;

	vgaarb_dbg(dev, "%s: %d\n", __func__, rsrc);
	vgaarb_dbg(dev, "%s: owns: %d\n", __func__, vgadev->owns);

	/* Check what resources we need to acquire */
	wants = rsrc & ~vgadev->owns;

	/* We already own everything, just mark locked & bye bye */
	if (wants == 0)
		goto lock_them;

	/* We don't need to request a legacy resource, we just enable
	 * appropriate decoding and go
	 */
	legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
	if (legacy_wants == 0)
		goto enable_them;

	/* Ok, we don't, let's find out how we need to kick off */
	list_for_each_entry(conflict, &vga_list, list) {
		unsigned int lwants = legacy_wants;
		unsigned int change_bridge = 0;

		/* Don't conflict with myself */
		if (vgadev == conflict)
			continue;

		/* Check if the architecture allows a conflict between those
		 * 2 devices or if they are on separate domains
		 */
		if (!vga_conflicts(vgadev->pdev, conflict->pdev))
			continue;

		/* We have a possible conflict. before we go further, we must
		 * check if we sit on the same bus as the conflicting device.
		 * if we don't, then we must tie both IO and MEM resources
		 * together since there is only a single bit controlling
		 * VGA forwarding on P2P bridges
		 */
		if (vgadev->pdev->bus != conflict->pdev->bus) {
			change_bridge = 1;
			lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
		}

		/* Check if the guy has a lock on the resource. If he does,
		 * return the conflicting entry
		 */
		if (conflict->locks & lwants)
			return conflict;

		/* Ok, now check if it owns the resource we want.  We can
		 * lock resources that are not decoded, therefore a device
		 * can own resources it doesn't decode.
		 */
		match = lwants & conflict->owns;
		if (!match)
			continue;

		/* looks like he doesn't have a lock, we can steal
		 * them from him
		 */

		flags = 0;
		pci_bits = 0;

		/* If we can't control legacy resources via the bridge, we
		 * also need to disable normal decoding.
		 */
		if (!conflict->bridge_has_one_vga) {
			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_MEM)
				pci_bits |= PCI_COMMAND_MEMORY;
			if ((match & conflict->decodes) & VGA_RSRC_LEGACY_IO)
				pci_bits |= PCI_COMMAND_IO;

			if (pci_bits) {
				vga_irq_set_state(conflict, false);
				flags |= PCI_VGA_STATE_CHANGE_DECODES;
			}
		}

		if (change_bridge)
			flags |= PCI_VGA_STATE_CHANGE_BRIDGE;

		pci_set_vga_state(conflict->pdev, false, pci_bits, flags);
		conflict->owns &= ~match;

		/* If we disabled normal decoding, reflect it in owns */
		if (pci_bits & PCI_COMMAND_MEMORY)
			conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
		if (pci_bits & PCI_COMMAND_IO)
			conflict->owns &= ~VGA_RSRC_NORMAL_IO;
	}

enable_them:
	/* ok dude, we got it, everybody conflicting has been disabled, let's
	 * enable us.  Mark any bits in "owns" regardless of whether we
	 * decoded them.  We can lock resources we don't decode, therefore
	 * we must track them via "owns".
	 */
	flags = 0;
	pci_bits = 0;

	if (!vgadev->bridge_has_one_vga) {
		flags |= PCI_VGA_STATE_CHANGE_DECODES;
		if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
			pci_bits |= PCI_COMMAND_MEMORY;
		if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
			pci_bits |= PCI_COMMAND_IO;
	}
	if (wants & VGA_RSRC_LEGACY_MASK)
		flags |= PCI_VGA_STATE_CHANGE_BRIDGE;

	pci_set_vga_state(vgadev->pdev, true, pci_bits, flags);

	if (!vgadev->bridge_has_one_vga)
		vga_irq_set_state(vgadev, true);

	vgadev->owns |= wants;
lock_them:
	vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
	if (rsrc & VGA_RSRC_LEGACY_IO)
		vgadev->io_lock_cnt++;
	if (rsrc & VGA_RSRC_LEGACY_MEM)
		vgadev->mem_lock_cnt++;
	if (rsrc & VGA_RSRC_NORMAL_IO)
		vgadev->io_norm_cnt++;
	if (rsrc & VGA_RSRC_NORMAL_MEM)
		vgadev->mem_norm_cnt++;

	return NULL;
}

static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
{
	struct device *dev = &vgadev->pdev->dev;
	unsigned int old_locks = vgadev->locks;

	vgaarb_dbg(dev, "%s\n", __func__);

	/* Update our counters, and account for equivalent legacy resources
	 * if we decode them
	 */
	if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
		vgadev->io_norm_cnt--;
		if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
			rsrc |= VGA_RSRC_LEGACY_IO;
	}
	if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
		vgadev->mem_norm_cnt--;
		if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
			rsrc |= VGA_RSRC_LEGACY_MEM;
	}
	if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
		vgadev->io_lock_cnt--;
	if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
		vgadev->mem_lock_cnt--;

	/* Just clear lock bits, we do lazy operations so we don't really
	 * have to bother about anything else at this point
	 */
	if (vgadev->io_lock_cnt == 0)
		vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
	if (vgadev->mem_lock_cnt == 0)
		vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;

	/* Kick the wait queue in case somebody was waiting if we actually
	 * released something
	 */
	if (old_locks != vgadev->locks)
		wake_up_all(&vga_wait_queue);
}

/**
 * vga_get - acquire & locks VGA resources
 * @pdev: pci device of the VGA card or NULL for the system default
 * @rsrc: bit mask of resources to acquire and lock
 * @interruptible: blocking should be interruptible by signals ?
 *
 * This function acquires VGA resources for the given card and mark those
 * resources locked. If the resource requested are "normal" (and not legacy)
 * resources, the arbiter will first check whether the card is doing legacy
 * decoding for that type of resource. If yes, the lock is "converted" into a
 * legacy resource lock.
 *
 * The arbiter will first look for all VGA cards that might conflict and disable
 * their IOs and/or Memory access, including VGA forwarding on P2P bridges if
 * necessary, so that the requested resources can be used. Then, the card is
 * marked as locking these resources and the IO and/or Memory accesses are
 * enabled on the card (including VGA forwarding on parent P2P bridges if any).
 *
 * This function will block if some conflicting card is already locking one of
 * the required resources (or any resource on a different bus segment, since P2P
 * bridges don't differentiate VGA memory and IO afaik). You can indicate
 * whether this blocking should be interruptible by a signal (for userland
 * interface) or not.
 *
 * Must not be called at interrupt time or in atomic context.  If the card
 * already owns the resources, the function succeeds.  Nested calls are
 * supported (a per-resource counter is maintained)
 *
 * On success, release the VGA resource again with vga_put().
 *
 * Returns:
 *
 * 0 on success, negative error code on failure.
 */
int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
{
	struct vga_device *vgadev, *conflict;
	unsigned long flags;
	wait_queue_t wait;
	int rc = 0;

	vga_check_first_use();
	/* The one who calls us should check for this, but lets be sure... */
	if (pdev == NULL)
		pdev = vga_default_device();
	if (pdev == NULL)
		return 0;

	for (;;) {
		spin_lock_irqsave(&vga_lock, flags);
		vgadev = vgadev_find(pdev);
		if (vgadev == NULL) {
			spin_unlock_irqrestore(&vga_lock, flags);
			rc = -ENODEV;
			break;
		}
		conflict = __vga_tryget(vgadev, rsrc);
		spin_unlock_irqrestore(&vga_lock, flags);
		if (conflict == NULL)
			break;


		/* We have a conflict, we wait until somebody kicks the
		 * work queue. Currently we have one work queue that we
		 * kick each time some resources are released, but it would
		 * be fairly easy to have a per device one so that we only
		 * need to attach to the conflicting device
		 */
		init_waitqueue_entry(&wait, current);
		add_wait_queue(&vga_wait_queue, &wait);
		set_current_state(interruptible ?
				  TASK_INTERRUPTIBLE :
				  TASK_UNINTERRUPTIBLE);
		if (interruptible && signal_pending(current)) {
			__set_current_state(TASK_RUNNING);
			remove_wait_queue(&vga_wait_queue, &wait);
			rc = -ERESTARTSYS;
			break;
		}
		schedule();
		remove_wait_queue(&vga_wait_queue, &wait);
	}
	return rc;
}
EXPORT_SYMBOL(vga_get);

/**
 * vga_tryget - try to acquire & lock legacy VGA resources
 * @pdev: pci devivce of VGA card or NULL for system default
 * @rsrc: bit mask of resources to acquire and lock
 *
 * This function performs the same operation as vga_get(), but will return an
 * error (-EBUSY) instead of blocking if the resources are already locked by
 * another card. It can be called in any context
 *
 * On success, release the VGA resource again with vga_put().
 *
 * Returns:
 *
 * 0 on success, negative error code on failure.
 */
int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
{
	struct vga_device *vgadev;
	unsigned long flags;
	int rc = 0;

	vga_check_first_use();

	/* The one who calls us should check for this, but lets be sure... */
	if (pdev == NULL)
		pdev = vga_default_device();
	if (pdev == NULL)
		return 0;
	spin_lock_irqsave(&vga_lock, flags);
	vgadev = vgadev_find(pdev);
	if (vgadev == NULL) {
		rc = -ENODEV;
		goto bail;
	}
	if (__vga_tryget(vgadev, rsrc))
		rc = -EBUSY;
bail:
	spin_unlock_irqrestore(&vga_lock, flags);
	return rc;
}
EXPORT_SYMBOL(vga_tryget);

/**
 * vga_put - release lock on legacy VGA resources
 * @pdev: pci device of VGA card or NULL for system default
 * @rsrc: but mask of resource to release
 *
 * This fuction releases resources previously locked by vga_get() or
 * vga_tryget(). The resources aren't disabled right away, so that a subsequence
 * vga_get() on the same card will succeed immediately. Resources have a
 * counter, so locks are only released if the counter reaches 0.
 */
void vga_put(struct pci_dev *pdev, unsigned int rsrc)
{
	struct vga_device *vgadev;
	unsigned long flags;

	/* The one who calls us should check for this, but lets be sure... */
	if (pdev == NULL)
		pdev = vga_default_device();
	if (pdev == NULL)
		return;
	spin_lock_irqsave(&vga_lock, flags);
	vgadev = vgadev_find(pdev);
	if (vgadev == NULL)
		goto bail;
	__vga_put(vgadev, rsrc);
bail:
	spin_unlock_irqrestore(&vga_lock, flags);
}
EXPORT_SYMBOL(vga_put);

/*
 * Rules for using a bridge to control a VGA descendant decoding: if a bridge
 * has only one VGA descendant then it can be used to control the VGA routing
 * for that device. It should always use the bridge closest to the device to
 * control it. If a bridge has a direct VGA descendant, but also have a sub-
 * bridge VGA descendant then we cannot use that bridge to control the direct
 * VGA descendant. So for every device we register, we need to iterate all
 * its parent bridges so we can invalidate any devices using them properly.
 */
static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
{
	struct vga_device *same_bridge_vgadev;
	struct pci_bus *new_bus, *bus;
	struct pci_dev *new_bridge, *bridge;

	vgadev->bridge_has_one_vga = true;

	if (list_empty(&vga_list))
		return;

	/* okay iterate the new devices bridge hierarachy */
	new_bus = vgadev->pdev->bus;
	while (new_bus) {
		new_bridge = new_bus->self;

		/* go through list of devices already registered */
		list_for_each_entry(same_bridge_vgadev, &vga_list, list) {
			bus = same_bridge_vgadev->pdev->bus;
			bridge = bus->self;

			/* see if the share a bridge with this device */
			if (new_bridge == bridge) {
				/*
				 * If their direct parent bridge is the same
				 * as any bridge of this device then it can't
				 * be used for that device.
				 */
				same_bridge_vgadev->bridge_has_one_vga = false;
			}

			/*
			 * Now iterate the previous devices bridge hierarchy.
			 * If the new devices parent bridge is in the other
			 * devices hierarchy then we can't use it to control
			 * this device
			 */
			while (bus) {
				bridge = bus->self;

				if (bridge && bridge == vgadev->pdev->bus->self)
					vgadev->bridge_has_one_vga = false;

				bus = bus->parent;
			}
		}
		new_bus = new_bus->parent;
	}
}

/*
 * Currently, we assume that the "initial" setup of the system is
 * not sane, that is we come up with conflicting devices and let
 * the arbiter's client decides if devices decodes or not legacy
 * things.
 */
static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
{
	struct vga_device *vgadev;
	unsigned long flags;
	struct pci_bus *bus;
	struct pci_dev *bridge;
	u16 cmd;

	/* Only deal with VGA class devices */
	if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
		return false;

	/* Allocate structure */
	vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
	if (vgadev == NULL) {
		vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");
		/*
		 * What to do on allocation failure ? For now, let's just do
		 * nothing, I'm not sure there is anything saner to be done.
		 */
		return false;
	}

	/* Take lock & check for duplicates */
	spin_lock_irqsave(&vga_lock, flags);
	if (vgadev_find(pdev) != NULL) {
		BUG_ON(1);
		goto fail;
	}
	vgadev->pdev = pdev;

	/* By default, assume we decode everything */
	vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
			  VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;

	/* by default mark it as decoding */
	vga_decode_count++;
	/* Mark that we "own" resources based on our enables, we will
	 * clear that below if the bridge isn't forwarding
	 */
	pci_read_config_word(pdev, PCI_COMMAND, &cmd);
	if (cmd & PCI_COMMAND_IO)
		vgadev->owns |= VGA_RSRC_LEGACY_IO;
	if (cmd & PCI_COMMAND_MEMORY)
		vgadev->owns |= VGA_RSRC_LEGACY_MEM;

	/* Check if VGA cycles can get down to us */
	bus = pdev->bus;
	while (bus) {
		bridge = bus->self;
		if (bridge) {
			u16 l;

			pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, &l);
			if (!(l & PCI_BRIDGE_CTL_VGA)) {
				vgadev->owns = 0;
				break;
			}
		}
		bus = bus->parent;
	}

	/* Deal with VGA default device. Use first enabled one
	 * by default if arch doesn't have it's own hook
	 */
	if (vga_default == NULL &&
	    ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)) {
		vgaarb_info(&pdev->dev, "setting as boot VGA device\n");
		vga_set_default_device(pdev);
	}

	vga_arbiter_check_bridge_sharing(vgadev);

	/* Add to the list */
	list_add(&vgadev->list, &vga_list);
	vga_count++;
	vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",
		vga_iostate_to_str(vgadev->decodes),
		vga_iostate_to_str(vgadev->owns),
		vga_iostate_to_str(vgadev->locks));

	spin_unlock_irqrestore(&vga_lock, flags);
	return true;
fail:
	spin_unlock_irqrestore(&vga_lock, flags);
	kfree(vgadev);
	return false;
}

static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
{
	struct vga_device *vgadev;
	unsigned long flags;
	bool ret = true;

	spin_lock_irqsave(&vga_lock, flags);
	vgadev = vgadev_find(pdev);
	if (vgadev == NULL) {
		ret = false;
		goto bail;
	}

	if (vga_default == pdev)
		vga_set_default_device(NULL);

	if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
		vga_decode_count--;

	/* Remove entry from list */
	list_del(&vgadev->list);
	vga_count--;
	/* Notify userland driver that the device is gone so it discards
	 * it's copies of the pci_dev pointer
	 */
	vga_arb_device_card_gone(pdev);

	/* Wake up all possible waiters */
	wake_up_all(&vga_wait_queue);
bail:
	spin_unlock_irqrestore(&vga_lock, flags);
	kfree(vgadev);
	return ret;
}

/* this is called with the lock */
static inline void vga_update_device_decodes(struct vga_device *vgadev,
					     int new_decodes)
{
	struct device *dev = &vgadev->pdev->dev;
	int old_decodes, decodes_removed, decodes_unlocked;

	old_decodes = vgadev->decodes;
	decodes_removed = ~new_decodes & old_decodes;
	decodes_unlocked = vgadev->locks & decodes_removed;
	vgadev->decodes = new_decodes;

	vgaarb_info(dev, "changed VGA decodes: olddecodes=%s,decodes=%s:owns=%s\n",
		vga_iostate_to_str(old_decodes),
		vga_iostate_to_str(vgadev->decodes),
		vga_iostate_to_str(vgadev->owns));

	/* if we removed locked decodes, lock count goes to zero, and release */
	if (decodes_unlocked) {
		if (decodes_unlocked & VGA_RSRC_LEGACY_IO)
			vgadev->io_lock_cnt = 0;
		if (decodes_unlocked & VGA_RSRC_LEGACY_MEM)
			vgadev->mem_lock_cnt = 0;
		__vga_put(vgadev, decodes_unlocked);
	}

	/* change decodes counter */
	if (old_decodes & VGA_RSRC_LEGACY_MASK &&
	    !(new_decodes & VGA_RSRC_LEGACY_MASK))
		vga_decode_count--;
	if (!(old_decodes & VGA_RSRC_LEGACY_MASK) &&
	    new_decodes & VGA_RSRC_LEGACY_MASK)
		vga_decode_count++;
	vgaarb_dbg(dev, "decoding count now is: %d\n", vga_decode_count);
}

static void __vga_set_legacy_decoding(struct pci_dev *pdev,
				      unsigned int decodes,
				      bool userspace)
{
	struct vga_device *vgadev;
	unsigned long flags;

	decodes &= VGA_RSRC_LEGACY_MASK;

	spin_lock_irqsave(&vga_lock, flags);
	vgadev = vgadev_find(pdev);
	if (vgadev == NULL)
		goto bail;

	/* don't let userspace futz with kernel driver decodes */
	if (userspace && vgadev->set_vga_decode)
		goto bail;

	/* update the device decodes + counter */
	vga_update_device_decodes(vgadev, decodes);

	/* XXX if somebody is going from "doesn't decode" to "decodes" state
	 * here, additional care must be taken as we may have pending owner
	 * ship of non-legacy region ...
	 */
bail:
	spin_unlock_irqrestore(&vga_lock, flags);
}

void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
{
	__vga_set_legacy_decoding(pdev, decodes, false);
}
EXPORT_SYMBOL(vga_set_legacy_decoding);

/**
 * vga_client_register - register or unregister a VGA arbitration client
 * @pdev: pci device of the VGA client
 * @cookie: client cookie to be used in callbacks
 * @irq_set_state: irq state change callback
 * @set_vga_decode: vga decode change callback
 *
 * Clients have two callback mechanisms they can use.
 *
 * @irq_set_state callback: If a client can't disable its GPUs VGA
 * resources, then we need to be able to ask it to turn off its irqs when we
 * turn off its mem and io decoding.
 *
 * @set_vga_decode callback: If a client can disable its GPU VGA resource, it
 * will get a callback from this to set the encode/decode state.
 *
 * Rationale: we cannot disable VGA decode resources unconditionally some single
 * GPU laptops seem to require ACPI or BIOS access to the VGA registers to
 * control things like backlights etc.  Hopefully newer multi-GPU laptops do
 * something saner, and desktops won't have any special ACPI for this. The
 * driver will get a callback when VGA arbitration is first used by userspace
 * since some older X servers have issues.
 *
 * This function does not check whether a client for @pdev has been registered
 * already.
 *
 * To unregister just call this function with @irq_set_state and @set_vga_decode
 * both set to NULL for the same @pdev as originally used to register them.
 *
 * Returns: 0 on success, -1 on failure
 */
int vga_client_register(struct pci_dev *pdev, void *cookie,
			void (*irq_set_state)(void *cookie, bool state),
			unsigned int (*set_vga_decode)(void *cookie,
						       bool decode))
{
	int ret = -ENODEV;
	struct vga_device *vgadev;
	unsigned long flags;

	spin_lock_irqsave(&vga_lock, flags);
	vgadev = vgadev_find(pdev);
	if (!vgadev)
		goto bail;

	vgadev->irq_set_state = irq_set_state;
	vgadev->set_vga_decode = set_vga_decode;
	vgadev->cookie = cookie;
	ret = 0;

bail:
	spin_unlock_irqrestore(&vga_lock, flags);
	return ret;

}
EXPORT_SYMBOL(vga_client_register);

/*
 * Char driver implementation
 *
 * Semantics is:
 *
 *  open       : open user instance of the arbitrer. by default, it's
 *                attached to the default VGA device of the system.
 *
 *  close      : close user instance, release locks
 *
 *  read       : return a string indicating the status of the target.
 *                an IO state string is of the form {io,mem,io+mem,none},
 *                mc and ic are respectively mem and io lock counts (for
 *                debugging/diagnostic only). "decodes" indicate what the
 *                card currently decodes, "owns" indicates what is currently
 *                enabled on it, and "locks" indicates what is locked by this
 *                card. If the card is unplugged, we get "invalid" then for
 *                card_ID and an -ENODEV error is returned for any command
 *                until a new card is targeted
 *
 *   "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
 *
 * write       : write a command to the arbiter. List of commands is:
 *
 *   target <card_ID>   : switch target to card <card_ID> (see below)
 *   lock <io_state>    : acquires locks on target ("none" is invalid io_state)
 *   trylock <io_state> : non-blocking acquire locks on target
 *   unlock <io_state>  : release locks on target
 *   unlock all         : release all locks on target held by this user
 *   decodes <io_state> : set the legacy decoding attributes for the card
 *
 * poll         : event if something change on any card (not just the target)
 *
 * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
 * to go back to the system default card (TODO: not implemented yet).
 * Currently, only PCI is supported as a prefix, but the userland API may
 * support other bus types in the future, even if the current kernel
 * implementation doesn't.
 *
 * Note about locks:
 *
 * The driver keeps track of which user has what locks on which card. It
 * supports stacking, like the kernel one. This complexifies the implementation
 * a bit, but makes the arbiter more tolerant to userspace problems and able
 * to properly cleanup in all cases when a process dies.
 * Currently, a max of 16 cards simultaneously can have locks issued from
 * userspace for a given user (file descriptor instance) of the arbiter.
 *
 * If the device is hot-unplugged, there is a hook inside the module to notify
 * they being added/removed in the system and automatically added/removed in
 * the arbiter.
 */

#define MAX_USER_CARDS         CONFIG_VGA_ARB_MAX_GPUS
#define PCI_INVALID_CARD       ((struct pci_dev *)-1UL)

/*
 * Each user has an array of these, tracking which cards have locks
 */
struct vga_arb_user_card {
	struct pci_dev *pdev;
	unsigned int mem_cnt;
	unsigned int io_cnt;
};

struct vga_arb_private {
	struct list_head list;
	struct pci_dev *target;
	struct vga_arb_user_card cards[MAX_USER_CARDS];
	spinlock_t lock;
};

static LIST_HEAD(vga_user_list);
static DEFINE_SPINLOCK(vga_user_lock);


/*
 * This function gets a string in the format: "PCI:domain:bus:dev.fn" and
 * returns the respective values. If the string is not in this format,
 * it returns 0.
 */
static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
			       unsigned int *bus, unsigned int *devfn)
{
	int n;
	unsigned int slot, func;


	n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
	if (n != 4)
		return 0;

	*devfn = PCI_DEVFN(slot, func);

	return 1;
}

static ssize_t vga_arb_read(struct file *file, char __user *buf,
			    size_t count, loff_t *ppos)
{
	struct vga_arb_private *priv = file->private_data;
	struct vga_device *vgadev;
	struct pci_dev *pdev;
	unsigned long flags;
	size_t len;
	int rc;
	char *lbuf;

	lbuf = kmalloc(1024, GFP_KERNEL);
	if (lbuf == NULL)
		return -ENOMEM;

	/* Shields against vga_arb_device_card_gone (pci_dev going
	 * away), and allows access to vga list
	 */
	spin_lock_irqsave(&vga_lock, flags);

	/* If we are targeting the default, use it */
	pdev = priv->target;
	if (pdev == NULL || pdev == PCI_INVALID_CARD) {
		spin_unlock_irqrestore(&vga_lock, flags);
		len = sprintf(lbuf, "invalid");
		goto done;
	}

	/* Find card vgadev structure */
	vgadev = vgadev_find(pdev);
	if (vgadev == NULL) {
		/* Wow, it's not in the list, that shouldn't happen,
		 * let's fix us up and return invalid card
		 */
		if (pdev == priv->target)
			vga_arb_device_card_gone(pdev);
		spin_unlock_irqrestore(&vga_lock, flags);
		len = sprintf(lbuf, "invalid");
		goto done;
	}

	/* Fill the buffer with infos */
	len = snprintf(lbuf, 1024,
		       "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
		       vga_decode_count, pci_name(pdev),
		       vga_iostate_to_str(vgadev->decodes),
		       vga_iostate_to_str(vgadev->owns),
		       vga_iostate_to_str(vgadev->locks),
		       vgadev->io_lock_cnt, vgadev->mem_lock_cnt);

	spin_unlock_irqrestore(&vga_lock, flags);
done:

	/* Copy that to user */
	if (len > count)
		len = count;
	rc = copy_to_user(buf, lbuf, len);
	kfree(lbuf);
	if (rc)
		return -EFAULT;
	return len;
}

/*
 * TODO: To avoid parsing inside kernel and to improve the speed we may
 * consider use ioctl here
 */
static ssize_t vga_arb_write(struct file *file, const char __user *buf,
			     size_t count, loff_t *ppos)
{
	struct vga_arb_private *priv = file->private_data;
	struct vga_arb_user_card *uc = NULL;
	struct pci_dev *pdev;

	unsigned int io_state;

	char kbuf[64], *curr_pos;
	size_t remaining = count;

	int ret_val;
	int i;

	if (count >= sizeof(kbuf))
		return -EINVAL;
	if (copy_from_user(kbuf, buf, count))
		return -EFAULT;
	curr_pos = kbuf;
	kbuf[count] = '\0';	/* Just to make sure... */

	if (strncmp(curr_pos, "lock ", 5) == 0) {
		curr_pos += 5;
		remaining -= 5;

		pr_debug("client 0x%p called 'lock'\n", priv);

		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
			ret_val = -EPROTO;
			goto done;
		}
		if (io_state == VGA_RSRC_NONE) {
			ret_val = -EPROTO;
			goto done;
		}

		pdev = priv->target;
		if (priv->target == NULL) {
			ret_val = -ENODEV;
			goto done;
		}

		vga_get_uninterruptible(pdev, io_state);

		/* Update the client's locks lists... */
		for (i = 0; i < MAX_USER_CARDS; i++) {
			if (priv->cards[i].pdev == pdev) {
				if (io_state & VGA_RSRC_LEGACY_IO)
					priv->cards[i].io_cnt++;
				if (io_state & VGA_RSRC_LEGACY_MEM)
					priv->cards[i].mem_cnt++;
				break;
			}
		}

		ret_val = count;
		goto done;
	} else if (strncmp(curr_pos, "unlock ", 7) == 0) {
		curr_pos += 7;
		remaining -= 7;

		pr_debug("client 0x%p called 'unlock'\n", priv);

		if (strncmp(curr_pos, "all", 3) == 0)
			io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
		else {
			if (!vga_str_to_iostate
			    (curr_pos, remaining, &io_state)) {
				ret_val = -EPROTO;
				goto done;
			}
			/* TODO: Add this?
			   if (io_state == VGA_RSRC_NONE) {
			   ret_val = -EPROTO;
			   goto done;
			   }
			  */
		}

		pdev = priv->target;
		if (priv->target == NULL) {
			ret_val = -ENODEV;
			goto done;
		}
		for (i = 0; i < MAX_USER_CARDS; i++) {
			if (priv->cards[i].pdev == pdev)
				uc = &priv->cards[i];
		}

		if (!uc) {
			ret_val = -EINVAL;
			goto done;
		}

		if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) {
			ret_val = -EINVAL;
			goto done;
		}

		if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) {
			ret_val = -EINVAL;
			goto done;
		}

		vga_put(pdev, io_state);

		if (io_state & VGA_RSRC_LEGACY_IO)
			uc->io_cnt--;
		if (io_state & VGA_RSRC_LEGACY_MEM)
			uc->mem_cnt--;

		ret_val = count;
		goto done;
	} else if (strncmp(curr_pos, "trylock ", 8) == 0) {
		curr_pos += 8;
		remaining -= 8;

		pr_debug("client 0x%p called 'trylock'\n", priv);

		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
			ret_val = -EPROTO;
			goto done;
		}
		/* TODO: Add this?
		   if (io_state == VGA_RSRC_NONE) {
		   ret_val = -EPROTO;
		   goto done;
		   }
		 */

		pdev = priv->target;
		if (priv->target == NULL) {
			ret_val = -ENODEV;
			goto done;
		}

		if (vga_tryget(pdev, io_state)) {
			/* Update the client's locks lists... */
			for (i = 0; i < MAX_USER_CARDS; i++) {
				if (priv->cards[i].pdev == pdev) {
					if (io_state & VGA_RSRC_LEGACY_IO)
						priv->cards[i].io_cnt++;
					if (io_state & VGA_RSRC_LEGACY_MEM)
						priv->cards[i].mem_cnt++;
					break;
				}
			}
			ret_val = count;
			goto done;
		} else {
			ret_val = -EBUSY;
			goto done;
		}

	} else if (strncmp(curr_pos, "target ", 7) == 0) {
		unsigned int domain, bus, devfn;
		struct vga_device *vgadev;

		curr_pos += 7;
		remaining -= 7;
		pr_debug("client 0x%p called 'target'\n", priv);
		/* if target is default */
		if (!strncmp(curr_pos, "default", 7))
			pdev = pci_dev_get(vga_default_device());
		else {
			if (!vga_pci_str_to_vars(curr_pos, remaining,
						 &domain, &bus, &devfn)) {
				ret_val = -EPROTO;
				goto done;
			}
			pdev = pci_get_domain_bus_and_slot(domain, bus, devfn);
			if (!pdev) {
				pr_debug("invalid PCI address %04x:%02x:%02x.%x\n",
					 domain, bus, PCI_SLOT(devfn),
					 PCI_FUNC(devfn));
				ret_val = -ENODEV;
				goto done;
			}

			pr_debug("%s ==> %04x:%02x:%02x.%x pdev %p\n", curr_pos,
				domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
				pdev);
		}

		vgadev = vgadev_find(pdev);
		pr_debug("vgadev %p\n", vgadev);
		if (vgadev == NULL) {
			if (pdev) {
				vgaarb_dbg(&pdev->dev, "not a VGA device\n");
				pci_dev_put(pdev);
			}

			ret_val = -ENODEV;
			goto done;
		}

		priv->target = pdev;
		for (i = 0; i < MAX_USER_CARDS; i++) {
			if (priv->cards[i].pdev == pdev)
				break;
			if (priv->cards[i].pdev == NULL) {
				priv->cards[i].pdev = pdev;
				priv->cards[i].io_cnt = 0;
				priv->cards[i].mem_cnt = 0;
				break;
			}
		}
		if (i == MAX_USER_CARDS) {
			vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n",
				MAX_USER_CARDS);
			pci_dev_put(pdev);
			/* XXX: which value to return? */
			ret_val =  -ENOMEM;
			goto done;
		}

		ret_val = count;
		pci_dev_put(pdev);
		goto done;


	} else if (strncmp(curr_pos, "decodes ", 8) == 0) {
		curr_pos += 8;
		remaining -= 8;
		pr_debug("client 0x%p called 'decodes'\n", priv);

		if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
			ret_val = -EPROTO;
			goto done;
		}
		pdev = priv->target;
		if (priv->target == NULL) {
			ret_val = -ENODEV;
			goto done;
		}

		__vga_set_legacy_decoding(pdev, io_state, true);
		ret_val = count;
		goto done;
	}
	/* If we got here, the message written is not part of the protocol! */
	return -EPROTO;

done:
	return ret_val;
}

static unsigned int vga_arb_fpoll(struct file *file, poll_table *wait)
{
	pr_debug("%s\n", __func__);

	poll_wait(file, &vga_wait_queue, wait);
	return POLLIN;
}

static int vga_arb_open(struct inode *inode, struct file *file)
{
	struct vga_arb_private *priv;
	unsigned long flags;

	pr_debug("%s\n", __func__);

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (priv == NULL)
		return -ENOMEM;
	spin_lock_init(&priv->lock);
	file->private_data = priv;

	spin_lock_irqsave(&vga_user_lock, flags);
	list_add(&priv->list, &vga_user_list);
	spin_unlock_irqrestore(&vga_user_lock, flags);

	/* Set the client' lists of locks */
	priv->target = vga_default_device(); /* Maybe this is still null! */
	priv->cards[0].pdev = priv->target;
	priv->cards[0].io_cnt = 0;
	priv->cards[0].mem_cnt = 0;


	return 0;
}

static int vga_arb_release(struct inode *inode, struct file *file)
{
	struct vga_arb_private *priv = file->private_data;
	struct vga_arb_user_card *uc;
	unsigned long flags;
	int i;

	pr_debug("%s\n", __func__);

	spin_lock_irqsave(&vga_user_lock, flags);
	list_del(&priv->list);
	for (i = 0; i < MAX_USER_CARDS; i++) {
		uc = &priv->cards[i];
		if (uc->pdev == NULL)
			continue;
		vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n",
			uc->io_cnt, uc->mem_cnt);
		while (uc->io_cnt--)
			vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
		while (uc->mem_cnt--)
			vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
	}
	spin_unlock_irqrestore(&vga_user_lock, flags);

	kfree(priv);

	return 0;
}

static void vga_arb_device_card_gone(struct pci_dev *pdev)
{
}

/*
 * callback any registered clients to let them know we have a
 * change in VGA cards
 */
static void vga_arbiter_notify_clients(void)
{
	struct vga_device *vgadev;
	unsigned long flags;
	uint32_t new_decodes;
	bool new_state;

	if (!vga_arbiter_used)
		return;

	spin_lock_irqsave(&vga_lock, flags);
	list_for_each_entry(vgadev, &vga_list, list) {
		if (vga_count > 1)
			new_state = false;
		else
			new_state = true;
		if (vgadev->set_vga_decode) {
			new_decodes = vgadev->set_vga_decode(vgadev->cookie,
							     new_state);
			vga_update_device_decodes(vgadev, new_decodes);
		}
	}
	spin_unlock_irqrestore(&vga_lock, flags);
}

static int pci_notify(struct notifier_block *nb, unsigned long action,
		      void *data)
{
	struct device *dev = data;
	struct pci_dev *pdev = to_pci_dev(dev);
	bool notify = false;

	vgaarb_dbg(dev, "%s\n", __func__);

	/* For now we're only intereted in devices added and removed. I didn't
	 * test this thing here, so someone needs to double check for the
	 * cases of hotplugable vga cards. */
	if (action == BUS_NOTIFY_ADD_DEVICE)
		notify = vga_arbiter_add_pci_device(pdev);
	else if (action == BUS_NOTIFY_DEL_DEVICE)
		notify = vga_arbiter_del_pci_device(pdev);

	if (notify)
		vga_arbiter_notify_clients();
	return 0;
}

static struct notifier_block pci_notifier = {
	.notifier_call = pci_notify,
};

static const struct file_operations vga_arb_device_fops = {
	.read = vga_arb_read,
	.write = vga_arb_write,
	.poll = vga_arb_fpoll,
	.open = vga_arb_open,
	.release = vga_arb_release,
	.llseek = noop_llseek,
};

static struct miscdevice vga_arb_device = {
	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
};

static int __init vga_arb_device_init(void)
{
	int rc;
	struct pci_dev *pdev;
	struct vga_device *vgadev;

	rc = misc_register(&vga_arb_device);
	if (rc < 0)
		pr_err("error %d registering device\n", rc);

	bus_register_notifier(&pci_bus_type, &pci_notifier);

	/* We add all pci devices satisfying vga class in the arbiter by
	 * default */
	pdev = NULL;
	while ((pdev =
		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
			       PCI_ANY_ID, pdev)) != NULL)
		vga_arbiter_add_pci_device(pdev);

	list_for_each_entry(vgadev, &vga_list, list) {
		struct device *dev = &vgadev->pdev->dev;
#if defined(CONFIG_X86) || defined(CONFIG_IA64)
		/*
		 * Override vga_arbiter_add_pci_device()'s I/O based detection
		 * as it may take the wrong device (e.g. on Apple system under
		 * EFI).
		 *
		 * Select the device owning the boot framebuffer if there is
		 * one.
		 */
		resource_size_t start, end, limit;
		unsigned long flags;
		int i;

		limit = screen_info.lfb_base + screen_info.lfb_size;

		/* Does firmware framebuffer belong to us? */
		for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
			flags = pci_resource_flags(vgadev->pdev, i);

			if ((flags & IORESOURCE_MEM) == 0)
				continue;

			start = pci_resource_start(vgadev->pdev, i);
			end  = pci_resource_end(vgadev->pdev, i);

			if (!start || !end)
				continue;

			if (screen_info.lfb_base < start || limit >= end)
				continue;

			if (!vga_default_device())
				vgaarb_info(dev, "setting as boot device\n");
			else if (vgadev->pdev != vga_default_device())
				vgaarb_info(dev, "overriding boot device\n");
			vga_set_default_device(vgadev->pdev);
		}
#endif
		if (vgadev->bridge_has_one_vga)
			vgaarb_info(dev, "bridge control possible\n");
		else
			vgaarb_info(dev, "no bridge control possible\n");
	}

	pr_info("loaded\n");
	return rc;
}
subsys_initcall(vga_arb_device_init);