aboutsummaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kernel/vio.c
blob: 77f64218abf3fd116031a3fd9b7fed71e0604e03 (plain) (blame)
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
/*
 * IBM PowerPC Virtual I/O Infrastructure Support.
 *
 *    Copyright (c) 2003,2008 IBM Corp.
 *     Dave Engebretsen engebret@us.ibm.com
 *     Santiago Leon santil@us.ibm.com
 *     Hollis Blanchard <hollisb@us.ibm.com>
 *     Stephen Rothwell
 *     Robert Jennings <rcjenn@us.ibm.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.
 */

#include <linux/types.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/kobject.h>

#include <asm/iommu.h>
#include <asm/dma.h>
#include <asm/vio.h>
#include <asm/prom.h>
#include <asm/firmware.h>
#include <asm/tce.h>
#include <asm/abs_addr.h>
#include <asm/page.h>
#include <asm/hvcall.h>
#include <asm/iseries/vio.h>
#include <asm/iseries/hv_types.h>
#include <asm/iseries/hv_lp_config.h>
#include <asm/iseries/hv_call_xm.h>
#include <asm/iseries/iommu.h>

static struct bus_type vio_bus_type;

static struct vio_dev vio_bus_device  = { /* fake "parent" device */
	.name = "vio",
	.type = "",
	.dev.init_name = "vio",
	.dev.bus = &vio_bus_type,
};

#ifdef CONFIG_PPC_SMLPAR
/**
 * vio_cmo_pool - A pool of IO memory for CMO use
 *
 * @size: The size of the pool in bytes
 * @free: The amount of free memory in the pool
 */
struct vio_cmo_pool {
	size_t size;
	size_t free;
};

/* How many ms to delay queued balance work */
#define VIO_CMO_BALANCE_DELAY 100

/* Portion out IO memory to CMO devices by this chunk size */
#define VIO_CMO_BALANCE_CHUNK 131072

/**
 * vio_cmo_dev_entry - A device that is CMO-enabled and requires entitlement
 *
 * @vio_dev: struct vio_dev pointer
 * @list: pointer to other devices on bus that are being tracked
 */
struct vio_cmo_dev_entry {
	struct vio_dev *viodev;
	struct list_head list;
};

/**
 * vio_cmo - VIO bus accounting structure for CMO entitlement
 *
 * @lock: spinlock for entire structure
 * @balance_q: work queue for balancing system entitlement
 * @device_list: list of CMO-enabled devices requiring entitlement
 * @entitled: total system entitlement in bytes
 * @reserve: pool of memory from which devices reserve entitlement, incl. spare
 * @excess: pool of excess entitlement not needed for device reserves or spare
 * @spare: IO memory for device hotplug functionality
 * @min: minimum necessary for system operation
 * @desired: desired memory for system operation
 * @curr: bytes currently allocated
 * @high: high water mark for IO data usage
 */
struct vio_cmo {
	spinlock_t lock;
	struct delayed_work balance_q;
	struct list_head device_list;
	size_t entitled;
	struct vio_cmo_pool reserve;
	struct vio_cmo_pool excess;
	size_t spare;
	size_t min;
	size_t desired;
	size_t curr;
	size_t high;
} vio_cmo;

/**
 * vio_cmo_OF_devices - Count the number of OF devices that have DMA windows
 */
static int vio_cmo_num_OF_devs(void)
{
	struct device_node *node_vroot;
	int count = 0;

	/*
	 * Count the number of vdevice entries with an
	 * ibm,my-dma-window OF property
	 */
	node_vroot = of_find_node_by_name(NULL, "vdevice");
	if (node_vroot) {
		struct device_node *of_node;
		struct property *prop;

		for_each_child_of_node(node_vroot, of_node) {
			prop = of_find_property(of_node, "ibm,my-dma-window",
			                       NULL);
			if (prop)
				count++;
		}
	}
	of_node_put(node_vroot);
	return count;
}

/**
 * vio_cmo_alloc - allocate IO memory for CMO-enable devices
 *
 * @viodev: VIO device requesting IO memory
 * @size: size of allocation requested
 *
 * Allocations come from memory reserved for the devices and any excess
 * IO memory available to all devices.  The spare pool used to service
 * hotplug must be equal to %VIO_CMO_MIN_ENT for the excess pool to be
 * made available.
 *
 * Return codes:
 *  0 for successful allocation and -ENOMEM for a failure
 */
static inline int vio_cmo_alloc(struct vio_dev *viodev, size_t size)
{
	unsigned long flags;
	size_t reserve_free = 0;
	size_t excess_free = 0;
	int ret = -ENOMEM;

	spin_lock_irqsave(&vio_cmo.lock, flags);

	/* Determine the amount of free entitlement available in reserve */
	if (viodev->cmo.entitled > viodev->cmo.allocated)
		reserve_free = viodev->cmo.entitled - viodev->cmo.allocated;

	/* If spare is not fulfilled, the excess pool can not be used. */
	if (vio_cmo.spare >= VIO_CMO_MIN_ENT)
		excess_free = vio_cmo.excess.free;

	/* The request can be satisfied */
	if ((reserve_free + excess_free) >= size) {
		vio_cmo.curr += size;
		if (vio_cmo.curr > vio_cmo.high)
			vio_cmo.high = vio_cmo.curr;
		viodev->cmo.allocated += size;
		size -= min(reserve_free, size);
		vio_cmo.excess.free -= size;
		ret = 0;
	}

	spin_unlock_irqrestore(&vio_cmo.lock, flags);
	return ret;
}

/**
 * vio_cmo_dealloc - deallocate IO memory from CMO-enable devices
 * @viodev: VIO device freeing IO memory
 * @size: size of deallocation
 *
 * IO memory is freed by the device back to the correct memory pools.
 * The spare pool is replenished first from either memory pool, then
 * the reserve pool is used to reduce device entitlement, the excess
 * pool is used to increase the reserve pool toward the desired entitlement
 * target, and then the remaining memory is returned to the pools.
 *
 */
static inline void vio_cmo_dealloc(struct vio_dev *viodev, size_t size)
{
	unsigned long flags;
	size_t spare_needed = 0;
	size_t excess_freed = 0;
	size_t reserve_freed = size;
	size_t tmp;
	int balance = 0;

	spin_lock_irqsave(&vio_cmo.lock, flags);
	vio_cmo.curr -= size;

	/* Amount of memory freed from the excess pool */
	if (viodev->cmo.allocated > viodev->cmo.entitled) {
		excess_freed = min(reserve_freed, (viodev->cmo.allocated -
		                                   viodev->cmo.entitled));
		reserve_freed -= excess_freed;
	}

	/* Remove allocation from device */
	viodev->cmo.allocated -= (reserve_freed + excess_freed);

	/* Spare is a subset of the reserve pool, replenish it first. */
	spare_needed = VIO_CMO_MIN_ENT - vio_cmo.spare;

	/*
	 * Replenish the spare in the reserve pool from the excess pool.
	 * This moves entitlement into the reserve pool.
	 */
	if (spare_needed && excess_freed) {
		tmp = min(excess_freed, spare_needed);
		vio_cmo.excess.size -= tmp;
		vio_cmo.reserve.size += tmp;
		vio_cmo.spare += tmp;
		excess_freed -= tmp;
		spare_needed -= tmp;
		balance = 1;
	}

	/*
	 * Replenish the spare in the reserve pool from the reserve pool.
	 * This removes entitlement from the device down to VIO_CMO_MIN_ENT,
	 * if needed, and gives it to the spare pool. The amount of used
	 * memory in this pool does not change.
	 */
	if (spare_needed && reserve_freed) {
		tmp = min(spare_needed, min(reserve_freed,
		                            (viodev->cmo.entitled -
		                             VIO_CMO_MIN_ENT)));

		vio_cmo.spare += tmp;
		viodev->cmo.entitled -= tmp;
		reserve_freed -= tmp;
		spare_needed -= tmp;
		balance = 1;
	}

	/*
	 * Increase the reserve pool until the desired allocation is met.
	 * Move an allocation freed from the excess pool into the reserve
	 * pool and schedule a balance operation.
	 */
	if (excess_freed && (vio_cmo.desired > vio_cmo.reserve.size)) {
		tmp = min(excess_freed, (vio_cmo.desired - vio_cmo.reserve.size));

		vio_cmo.excess.size -= tmp;
		vio_cmo.reserve.size += tmp;
		excess_freed -= tmp;
		balance = 1;
	}

	/* Return memory from the excess pool to that pool */
	if (excess_freed)
		vio_cmo.excess.free += excess_freed;

	if (balance)
		schedule_delayed_work(&vio_cmo.balance_q, VIO_CMO_BALANCE_DELAY);
	spin_unlock_irqrestore(&vio_cmo.lock, flags);
}

/**
 * vio_cmo_entitlement_update - Manage system entitlement changes
 *
 * @new_entitlement: new system entitlement to attempt to accommodate
 *
 * Increases in entitlement will be used to fulfill the spare entitlement
 * and the rest is given to the excess pool.  Decreases, if they are
 * possible, come from the excess pool and from unused device entitlement
 *
 * Returns: 0 on success, -ENOMEM when change can not be made
 */
int vio_cmo_entitlement_update(size_t new_entitlement)
{
	struct vio_dev *viodev;
	struct vio_cmo_dev_entry *dev_ent;
	unsigned long flags;
	size_t avail, delta, tmp;

	spin_lock_irqsave(&vio_cmo.lock, flags);

	/* Entitlement increases */
	if (new_entitlement > vio_cmo.entitled) {
		delta = new_entitlement - vio_cmo.entitled;

		/* Fulfill spare allocation */
		if (vio_cmo.spare < VIO_CMO_MIN_ENT) {
			tmp = min(delta, (VIO_CMO_MIN_ENT - vio_cmo.spare));
			vio_cmo.spare += tmp;
			vio_cmo.reserve.size += tmp;
			delta -= tmp;
		}

		/* Remaining new allocation goes to the excess pool */
		vio_cmo.entitled += delta;
		vio_cmo.excess.size += delta;
		vio_cmo.excess.free += delta;

		goto out;
	}

	/* Entitlement decreases */
	delta = vio_cmo.entitled - new_entitlement;
	avail = vio_cmo.excess.free;

	/*
	 * Need to check how much unused entitlement each device can
	 * sacrifice to fulfill entitlement change.
	 */
	list_for_each_entry(dev_ent, &vio_cmo.device_list, list) {
		if (avail >= delta)
			break;

		viodev = dev_ent->viodev;
		if ((viodev->cmo.entitled > viodev->cmo.allocated) &&
		    (viodev->cmo.entitled > VIO_CMO_MIN_ENT))
				avail += viodev->cmo.entitled -
				         max_t(size_t, viodev->cmo.allocated,
				               VIO_CMO_MIN_ENT);
	}

	if (delta <= avail) {
		vio_cmo.entitled -= delta;

		/* Take entitlement from the excess pool first */
		tmp = min(vio_cmo.excess.free, delta);
		vio_cmo.excess.size -= tmp;
		vio_cmo.excess.free -= tmp;
		delta -= tmp;

		/*
		 * Remove all but VIO_CMO_MIN_ENT bytes from devices
		 * until entitlement change is served
		 */
		list_for_each_entry(dev_ent, &vio_cmo.device_list, list) {
			if (!delta)
				break;

			viodev = dev_ent->viodev;
			tmp = 0;
			if ((viodev->cmo.entitled > viodev->cmo.allocated) &&
			    (viodev->cmo.entitled > VIO_CMO_MIN_ENT))
				tmp = viodev->cmo.entitled -
				      max_t(size_t, viodev->cmo.allocated,
				            VIO_CMO_MIN_ENT);
			viodev->cmo.entitled -= min(tmp, delta);
			delta -= min(tmp, delta);
		}
	} else {
		spin_unlock_irqrestore(&vio_cmo.lock, flags);
		return -ENOMEM;
	}

out:
	schedule_delayed_work(&vio_cmo.balance_q, 0);
	spin_unlock_irqrestore(&vio_cmo.lock, flags);
	return 0;
}

/**
 * vio_cmo_balance - Balance entitlement among devices
 *
 * @work: work queue structure for this operation
 *
 * Any system entitlement above the minimum needed for devices, or
 * already allocated to devices, can be distributed to the devices.
 * The list of devices is iterated through to recalculate the desired
 * entitlement level and to determine how much entitlement above the
 * minimum entitlement is allocated to devices.
 *
 * Small chunks of the available entitlement are given to devices until
 * their requirements are fulfilled or there is no entitlement left to give.
 * Upon completion sizes of the reserve and excess pools are calculated.
 *
 * The system minimum entitlement level is also recalculated here.
 * Entitlement will be reserved for devices even after vio_bus_remove to
 * accommodate reloading the driver.  The OF tree is walked to count the
 * number of devices present and this will remove entitlement for devices
 * that have actually left the system after having vio_bus_remove called.
 */
static void vio_cmo_balance(struct work_struct *work)
{
	struct vio_cmo *cmo;
	struct vio_dev *viodev;
	struct vio_cmo_dev_entry *dev_ent;
	unsigned long flags;
	size_t avail = 0, level, chunk, need;
	int devcount = 0, fulfilled;

	cmo = container_of(work, struct vio_cmo, balance_q.work);

	spin_lock_irqsave(&vio_cmo.lock, flags);

	/* Calculate minimum entitlement and fulfill spare */
	cmo->min = vio_cmo_num_OF_devs() * VIO_CMO_MIN_ENT;
	BUG_ON(cmo->min > cmo->entitled);
	cmo->spare = min_t(size_t, VIO_CMO_MIN_ENT, (cmo->entitled - cmo->min));
	cmo->min += cmo->spare;
	cmo->desired = cmo->min;

	/*
	 * Determine how much entitlement is available and reset device
	 * entitlements
	 */
	avail = cmo->entitled - cmo->spare;
	list_for_each_entry(dev_ent, &vio_cmo.device_list, list) {
		viodev = dev_ent->viodev;
		devcount++;
		viodev->cmo.entitled = VIO_CMO_MIN_ENT;
		cmo->desired += (viodev->cmo.desired - VIO_CMO_MIN_ENT);
		avail -= max_t(size_t, viodev->cmo.allocated, VIO_CMO_MIN_ENT);
	}

	/*
	 * Having provided each device with the minimum entitlement, loop
	 * over the devices portioning out the remaining entitlement
	 * until there is nothing left.
	 */
	level = VIO_CMO_MIN_ENT;
	while (avail) {
		fulfilled = 0;
		list_for_each_entry(dev_ent, &vio_cmo.device_list, list) {
			viodev = dev_ent->viodev;

			if (viodev->cmo.desired <= level) {
				fulfilled++;
				continue;
			}

			/*
			 * Give the device up to VIO_CMO_BALANCE_CHUNK
			 * bytes of entitlement, but do not exceed the
			 * desired level of entitlement for the device.
			 */
			chunk = min_t(size_t, avail, VIO_CMO_BALANCE_CHUNK);
			chunk = min(chunk, (viodev->cmo.desired -
			                    viodev->cmo.entitled));
			viodev->cmo.entitled += chunk;

			/*
			 * If the memory for this entitlement increase was
			 * already allocated to the device it does not come
			 * from the available pool being portioned out.
			 */
			need = max(viodev->cmo.allocated, viodev->cmo.entitled)-
			       max(viodev->cmo.allocated, level);
			avail -= need;

		}
		if (fulfilled == devcount)
			break;
		level += VIO_CMO_BALANCE_CHUNK;
	}

	/* Calculate new reserve and excess pool sizes */
	cmo->reserve.size = cmo->min;
	cmo->excess.free = 0;
	cmo->excess.size = 0;
	need = 0;
	list_for_each_entry(dev_ent, &vio_cmo.device_list, list) {
		viodev = dev_ent->viodev;
		/* Calculated reserve size above the minimum entitlement */
		if (viodev->cmo.entitled)
			cmo->reserve.size += (viodev->cmo.entitled -
			                      VIO_CMO_MIN_ENT);
		/* Calculated used excess entitlement */
		if (viodev->cmo.allocated > viodev->cmo.entitled)
			need += viodev->cmo.allocated - viodev->cmo.entitled;
	}
	cmo->excess.size = cmo->entitled - cmo->reserve.size;
	cmo->excess.free = cmo->excess.size - need;

	cancel_delayed_work(to_delayed_work(work));
	spin_unlock_irqrestore(&vio_cmo.lock, flags);
}

static void *vio_dma_iommu_alloc_coherent(struct device *dev, size_t size,
                                          dma_addr_t *dma_handle, gfp_t flag)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	void *ret;

	if (vio_cmo_alloc(viodev, roundup(size, PAGE_SIZE))) {
		atomic_inc(&viodev->cmo.allocs_failed);
		return NULL;
	}

	ret = dma_iommu_ops.alloc_coherent(dev, size, dma_handle, flag);
	if (unlikely(ret == NULL)) {
		vio_cmo_dealloc(viodev, roundup(size, PAGE_SIZE));
		atomic_inc(&viodev->cmo.allocs_failed);
	}

	return ret;
}

static void vio_dma_iommu_free_coherent(struct device *dev, size_t size,
                                        void *vaddr, dma_addr_t dma_handle)
{
	struct vio_dev *viodev = to_vio_dev(dev);

	dma_iommu_ops.free_coherent(dev, size, vaddr, dma_handle);

	vio_cmo_dealloc(viodev, roundup(size, PAGE_SIZE));
}

static dma_addr_t vio_dma_iommu_map_page(struct device *dev, struct page *page,
                                         unsigned long offset, size_t size,
                                         enum dma_data_direction direction,
                                         struct dma_attrs *attrs)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	dma_addr_t ret = DMA_ERROR_CODE;

	if (vio_cmo_alloc(viodev, roundup(size, IOMMU_PAGE_SIZE))) {
		atomic_inc(&viodev->cmo.allocs_failed);
		return ret;
	}

	ret = dma_iommu_ops.map_page(dev, page, offset, size, direction, attrs);
	if (unlikely(dma_mapping_error(dev, ret))) {
		vio_cmo_dealloc(viodev, roundup(size, IOMMU_PAGE_SIZE));
		atomic_inc(&viodev->cmo.allocs_failed);
	}

	return ret;
}

static void vio_dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
				     size_t size,
				     enum dma_data_direction direction,
				     struct dma_attrs *attrs)
{
	struct vio_dev *viodev = to_vio_dev(dev);

	dma_iommu_ops.unmap_page(dev, dma_handle, size, direction, attrs);

	vio_cmo_dealloc(viodev, roundup(size, IOMMU_PAGE_SIZE));
}

static int vio_dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
                                int nelems, enum dma_data_direction direction,
                                struct dma_attrs *attrs)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	struct scatterlist *sgl;
	int ret, count = 0;
	size_t alloc_size = 0;

	for (sgl = sglist; count < nelems; count++, sgl++)
		alloc_size += roundup(sgl->length, IOMMU_PAGE_SIZE);

	if (vio_cmo_alloc(viodev, alloc_size)) {
		atomic_inc(&viodev->cmo.allocs_failed);
		return 0;
	}

	ret = dma_iommu_ops.map_sg(dev, sglist, nelems, direction, attrs);

	if (unlikely(!ret)) {
		vio_cmo_dealloc(viodev, alloc_size);
		atomic_inc(&viodev->cmo.allocs_failed);
		return ret;
	}

	for (sgl = sglist, count = 0; count < ret; count++, sgl++)
		alloc_size -= roundup(sgl->dma_length, IOMMU_PAGE_SIZE);
	if (alloc_size)
		vio_cmo_dealloc(viodev, alloc_size);

	return ret;
}

static void vio_dma_iommu_unmap_sg(struct device *dev,
		struct scatterlist *sglist, int nelems,
		enum dma_data_direction direction,
		struct dma_attrs *attrs)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	struct scatterlist *sgl;
	size_t alloc_size = 0;
	int count = 0;

	for (sgl = sglist; count < nelems; count++, sgl++)
		alloc_size += roundup(sgl->dma_length, IOMMU_PAGE_SIZE);

	dma_iommu_ops.unmap_sg(dev, sglist, nelems, direction, attrs);

	vio_cmo_dealloc(viodev, alloc_size);
}

struct dma_map_ops vio_dma_mapping_ops = {
	.alloc_coherent = vio_dma_iommu_alloc_coherent,
	.free_coherent  = vio_dma_iommu_free_coherent,
	.map_sg         = vio_dma_iommu_map_sg,
	.unmap_sg       = vio_dma_iommu_unmap_sg,
	.map_page       = vio_dma_iommu_map_page,
	.unmap_page     = vio_dma_iommu_unmap_page,

};

/**
 * vio_cmo_set_dev_desired - Set desired entitlement for a device
 *
 * @viodev: struct vio_dev for device to alter
 * @new_desired: new desired entitlement level in bytes
 *
 * For use by devices to request a change to their entitlement at runtime or
 * through sysfs.  The desired entitlement level is changed and a balancing
 * of system resources is scheduled to run in the future.
 */
void vio_cmo_set_dev_desired(struct vio_dev *viodev, size_t desired)
{
	unsigned long flags;
	struct vio_cmo_dev_entry *dev_ent;
	int found = 0;

	if (!firmware_has_feature(FW_FEATURE_CMO))
		return;

	spin_lock_irqsave(&vio_cmo.lock, flags);
	if (desired < VIO_CMO_MIN_ENT)
		desired = VIO_CMO_MIN_ENT;

	/*
	 * Changes will not be made for devices not in the device list.
	 * If it is not in the device list, then no driver is loaded
	 * for the device and it can not receive entitlement.
	 */
	list_for_each_entry(dev_ent, &vio_cmo.device_list, list)
		if (viodev == dev_ent->viodev) {
			found = 1;
			break;
		}
	if (!found)
		return;

	/* Increase/decrease in desired device entitlement */
	if (desired >= viodev->cmo.desired) {
		/* Just bump the bus and device values prior to a balance*/
		vio_cmo.desired += desired - viodev->cmo.desired;
		viodev->cmo.desired = desired;
	} else {
		/* Decrease bus and device values for desired entitlement */
		vio_cmo.desired -= viodev->cmo.desired - desired;
		viodev->cmo.desired = desired;
		/*
		 * If less entitlement is desired than current entitlement, move
		 * any reserve memory in the change region to the excess pool.
		 */
		if (viodev->cmo.entitled > desired) {
			vio_cmo.reserve.size -= viodev->cmo.entitled - desired;
			vio_cmo.excess.size += viodev->cmo.entitled - desired;
			/*
			 * If entitlement moving from the reserve pool to the
			 * excess pool is currently unused, add to the excess
			 * free counter.
			 */
			if (viodev->cmo.allocated < viodev->cmo.entitled)
				vio_cmo.excess.free += viodev->cmo.entitled -
				                       max(viodev->cmo.allocated, desired);
			viodev->cmo.entitled = desired;
		}
	}
	schedule_delayed_work(&vio_cmo.balance_q, 0);
	spin_unlock_irqrestore(&vio_cmo.lock, flags);
}

/**
 * vio_cmo_bus_probe - Handle CMO specific bus probe activities
 *
 * @viodev - Pointer to struct vio_dev for device
 *
 * Determine the devices IO memory entitlement needs, attempting
 * to satisfy the system minimum entitlement at first and scheduling
 * a balance operation to take care of the rest at a later time.
 *
 * Returns: 0 on success, -EINVAL when device doesn't support CMO, and
 *          -ENOMEM when entitlement is not available for device or
 *          device entry.
 *
 */
static int vio_cmo_bus_probe(struct vio_dev *viodev)
{
	struct vio_cmo_dev_entry *dev_ent;
	struct device *dev = &viodev->dev;
	struct vio_driver *viodrv = to_vio_driver(dev->driver);
	unsigned long flags;
	size_t size;

	/*
	 * Check to see that device has a DMA window and configure
	 * entitlement for the device.
	 */
	if (of_get_property(viodev->dev.archdata.of_node,
	                    "ibm,my-dma-window", NULL)) {
		/* Check that the driver is CMO enabled and get desired DMA */
		if (!viodrv->get_desired_dma) {
			dev_err(dev, "%s: device driver does not support CMO\n",
			        __func__);
			return -EINVAL;
		}

		viodev->cmo.desired = IOMMU_PAGE_ALIGN(viodrv->get_desired_dma(viodev));
		if (viodev->cmo.desired < VIO_CMO_MIN_ENT)
			viodev->cmo.desired = VIO_CMO_MIN_ENT;
		size = VIO_CMO_MIN_ENT;

		dev_ent = kmalloc(sizeof(struct vio_cmo_dev_entry),
		                  GFP_KERNEL);
		if (!dev_ent)
			return -ENOMEM;

		dev_ent->viodev = viodev;
		spin_lock_irqsave(&vio_cmo.lock, flags);
		list_add(&dev_ent->list, &vio_cmo.device_list);
	} else {
		viodev->cmo.desired = 0;
		size = 0;
		spin_lock_irqsave(&vio_cmo.lock, flags);
	}

	/*
	 * If the needs for vio_cmo.min have not changed since they
	 * were last set, the number of devices in the OF tree has
	 * been constant and the IO memory for this is already in
	 * the reserve pool.
	 */
	if (vio_cmo.min == ((vio_cmo_num_OF_devs() + 1) *
	                    VIO_CMO_MIN_ENT)) {
		/* Updated desired entitlement if device requires it */
		if (size)
			vio_cmo.desired += (viodev->cmo.desired -
		                        VIO_CMO_MIN_ENT);
	} else {
		size_t tmp;

		tmp = vio_cmo.spare + vio_cmo.excess.free;
		if (tmp < size) {
			dev_err(dev, "%s: insufficient free "
			        "entitlement to add device. "
			        "Need %lu, have %lu\n", __func__,
				size, (vio_cmo.spare + tmp));
			spin_unlock_irqrestore(&vio_cmo.lock, flags);
			return -ENOMEM;
		}

		/* Use excess pool first to fulfill request */
		tmp = min(size, vio_cmo.excess.free);
		vio_cmo.excess.free -= tmp;
		vio_cmo.excess.size -= tmp;
		vio_cmo.reserve.size += tmp;

		/* Use spare if excess pool was insufficient */
		vio_cmo.spare -= size - tmp;

		/* Update bus accounting */
		vio_cmo.min += size;
		vio_cmo.desired += viodev->cmo.desired;
	}
	spin_unlock_irqrestore(&vio_cmo.lock, flags);
	return 0;
}

/**
 * vio_cmo_bus_remove - Handle CMO specific bus removal activities
 *
 * @viodev - Pointer to struct vio_dev for device
 *
 * Remove the device from the cmo device list.  The minimum entitlement
 * will be reserved for the device as long as it is in the system.  The
 * rest of the entitlement the device had been allocated will be returned
 * to the system.
 */
static void vio_cmo_bus_remove(struct vio_dev *viodev)
{
	struct vio_cmo_dev_entry *dev_ent;
	unsigned long flags;
	size_t tmp;

	spin_lock_irqsave(&vio_cmo.lock, flags);
	if (viodev->cmo.allocated) {
		dev_err(&viodev->dev, "%s: device had %lu bytes of IO "
		        "allocated after remove operation.\n",
		        __func__, viodev->cmo.allocated);
		BUG();
	}

	/*
	 * Remove the device from the device list being maintained for
	 * CMO enabled devices.
	 */
	list_for_each_entry(dev_ent, &vio_cmo.device_list, list)
		if (viodev == dev_ent->viodev) {
			list_del(&dev_ent->list);
			kfree(dev_ent);
			break;
		}

	/*
	 * Devices may not require any entitlement and they do not need
	 * to be processed.  Otherwise, return the device's entitlement
	 * back to the pools.
	 */
	if (viodev->cmo.entitled) {
		/*
		 * This device has not yet left the OF tree, it's
		 * minimum entitlement remains in vio_cmo.min and
		 * vio_cmo.desired
		 */
		vio_cmo.desired -= (viodev->cmo.desired - VIO_CMO_MIN_ENT);

		/*
		 * Save min allocation for device in reserve as long
		 * as it exists in OF tree as determined by later
		 * balance operation
		 */
		viodev->cmo.entitled -= VIO_CMO_MIN_ENT;

		/* Replenish spare from freed reserve pool */
		if (viodev->cmo.entitled && (vio_cmo.spare < VIO_CMO_MIN_ENT)) {
			tmp = min(viodev->cmo.entitled, (VIO_CMO_MIN_ENT -
			                                 vio_cmo.spare));
			vio_cmo.spare += tmp;
			viodev->cmo.entitled -= tmp;
		}

		/* Remaining reserve goes to excess pool */
		vio_cmo.excess.size += viodev->cmo.entitled;
		vio_cmo.excess.free += viodev->cmo.entitled;
		vio_cmo.reserve.size -= viodev->cmo.entitled;

		/*
		 * Until the device is removed it will keep a
		 * minimum entitlement; this will guarantee that
		 * a module unload/load will result in a success.
		 */
		viodev->cmo.entitled = VIO_CMO_MIN_ENT;
		viodev->cmo.desired = VIO_CMO_MIN_ENT;
		atomic_set(&viodev->cmo.allocs_failed, 0);
	}

	spin_unlock_irqrestore(&vio_cmo.lock, flags);
}

static void vio_cmo_set_dma_ops(struct vio_dev *viodev)
{
	vio_dma_mapping_ops.dma_supported = dma_iommu_ops.dma_supported;
	viodev->dev.archdata.dma_ops = &vio_dma_mapping_ops;
}

/**
 * vio_cmo_bus_init - CMO entitlement initialization at bus init time
 *
 * Set up the reserve and excess entitlement pools based on available
 * system entitlement and the number of devices in the OF tree that
 * require entitlement in the reserve pool.
 */
static void vio_cmo_bus_init(void)
{
	struct hvcall_mpp_data mpp_data;
	int err;

	memset(&vio_cmo, 0, sizeof(struct vio_cmo));
	spin_lock_init(&vio_cmo.lock);
	INIT_LIST_HEAD(&vio_cmo.device_list);
	INIT_DELAYED_WORK(&vio_cmo.balance_q, vio_cmo_balance);

	/* Get current system entitlement */
	err = h_get_mpp(&mpp_data);

	/*
	 * On failure, continue with entitlement set to 0, will panic()
	 * later when spare is reserved.
	 */
	if (err != H_SUCCESS) {
		printk(KERN_ERR "%s: unable to determine system IO "\
		       "entitlement. (%d)\n", __func__, err);
		vio_cmo.entitled = 0;
	} else {
		vio_cmo.entitled = mpp_data.entitled_mem;
	}

	/* Set reservation and check against entitlement */
	vio_cmo.spare = VIO_CMO_MIN_ENT;
	vio_cmo.reserve.size = vio_cmo.spare;
	vio_cmo.reserve.size += (vio_cmo_num_OF_devs() *
	                         VIO_CMO_MIN_ENT);
	if (vio_cmo.reserve.size > vio_cmo.entitled) {
		printk(KERN_ERR "%s: insufficient system entitlement\n",
		       __func__);
		panic("%s: Insufficient system entitlement", __func__);
	}

	/* Set the remaining accounting variables */
	vio_cmo.excess.size = vio_cmo.entitled - vio_cmo.reserve.size;
	vio_cmo.excess.free = vio_cmo.excess.size;
	vio_cmo.min = vio_cmo.reserve.size;
	vio_cmo.desired = vio_cmo.reserve.size;
}

/* sysfs device functions and data structures for CMO */

#define viodev_cmo_rd_attr(name)                                        \
static ssize_t viodev_cmo_##name##_show(struct device *dev,             \
                                        struct device_attribute *attr,  \
                                         char *buf)                     \
{                                                                       \
	return sprintf(buf, "%lu\n", to_vio_dev(dev)->cmo.name);        \
}

static ssize_t viodev_cmo_allocs_failed_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	return sprintf(buf, "%d\n", atomic_read(&viodev->cmo.allocs_failed));
}

static ssize_t viodev_cmo_allocs_failed_reset(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	atomic_set(&viodev->cmo.allocs_failed, 0);
	return count;
}

static ssize_t viodev_cmo_desired_set(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	size_t new_desired;
	int ret;

	ret = strict_strtoul(buf, 10, &new_desired);
	if (ret)
		return ret;

	vio_cmo_set_dev_desired(viodev, new_desired);
	return count;
}

viodev_cmo_rd_attr(desired);
viodev_cmo_rd_attr(entitled);
viodev_cmo_rd_attr(allocated);

static ssize_t name_show(struct device *, struct device_attribute *, char *);
static ssize_t devspec_show(struct device *, struct device_attribute *, char *);
static struct device_attribute vio_cmo_dev_attrs[] = {
	__ATTR_RO(name),
	__ATTR_RO(devspec),
	__ATTR(cmo_desired,       S_IWUSR|S_IRUSR|S_IWGRP|S_IRGRP|S_IROTH,
	       viodev_cmo_desired_show, viodev_cmo_desired_set),
	__ATTR(cmo_entitled,      S_IRUGO, viodev_cmo_entitled_show,      NULL),
	__ATTR(cmo_allocated,     S_IRUGO, viodev_cmo_allocated_show,     NULL),
	__ATTR(cmo_allocs_failed, S_IWUSR|S_IRUSR|S_IWGRP|S_IRGRP|S_IROTH,
	       viodev_cmo_allocs_failed_show, viodev_cmo_allocs_failed_reset),
	__ATTR_NULL
};

/* sysfs bus functions and data structures for CMO */

#define viobus_cmo_rd_attr(name)                                        \
static ssize_t                                                          \
viobus_cmo_##name##_show(struct bus_type *bt, char *buf)                \
{                                                                       \
	return sprintf(buf, "%lu\n", vio_cmo.name);                     \
}

#define viobus_cmo_pool_rd_attr(name, var)                              \
static ssize_t                                                          \
viobus_cmo_##name##_pool_show_##var(struct bus_type *bt, char *buf)     \
{                                                                       \
	return sprintf(buf, "%lu\n", vio_cmo.name.var);                 \
}

static ssize_t viobus_cmo_high_reset(struct bus_type *bt, const char *buf,
                                     size_t count)
{
	unsigned long flags;

	spin_lock_irqsave(&vio_cmo.lock, flags);
	vio_cmo.high = vio_cmo.curr;
	spin_unlock_irqrestore(&vio_cmo.lock, flags);

	return count;
}

viobus_cmo_rd_attr(entitled);
viobus_cmo_pool_rd_attr(reserve, size);
viobus_cmo_pool_rd_attr(excess, size);
viobus_cmo_pool_rd_attr(excess, free);
viobus_cmo_rd_attr(spare);
viobus_cmo_rd_attr(min);
viobus_cmo_rd_attr(desired);
viobus_cmo_rd_attr(curr);
viobus_cmo_rd_attr(high);

static struct bus_attribute vio_cmo_bus_attrs[] = {
	__ATTR(cmo_entitled, S_IRUGO, viobus_cmo_entitled_show, NULL),
	__ATTR(cmo_reserve_size, S_IRUGO, viobus_cmo_reserve_pool_show_size, NULL),
	__ATTR(cmo_excess_size, S_IRUGO, viobus_cmo_excess_pool_show_size, NULL),
	__ATTR(cmo_excess_free, S_IRUGO, viobus_cmo_excess_pool_show_free, NULL),
	__ATTR(cmo_spare,   S_IRUGO, viobus_cmo_spare_show,   NULL),
	__ATTR(cmo_min,     S_IRUGO, viobus_cmo_min_show,     NULL),
	__ATTR(cmo_desired, S_IRUGO, viobus_cmo_desired_show, NULL),
	__ATTR(cmo_curr,    S_IRUGO, viobus_cmo_curr_show,    NULL),
	__ATTR(cmo_high,    S_IWUSR|S_IRUSR|S_IWGRP|S_IRGRP|S_IROTH,
	       viobus_cmo_high_show, viobus_cmo_high_reset),
	__ATTR_NULL
};

static void vio_cmo_sysfs_init(void)
{
	vio_bus_type.dev_attrs = vio_cmo_dev_attrs;
	vio_bus_type.bus_attrs = vio_cmo_bus_attrs;
}
#else /* CONFIG_PPC_SMLPAR */
/* Dummy functions for iSeries platform */
int vio_cmo_entitlement_update(size_t new_entitlement) { return 0; }
void vio_cmo_set_dev_desired(struct vio_dev *viodev, size_t desired) {}
static int vio_cmo_bus_probe(struct vio_dev *viodev) { return 0; }
static void vio_cmo_bus_remove(struct vio_dev *viodev) {}
static void vio_cmo_set_dma_ops(struct vio_dev *viodev) {}
static void vio_cmo_bus_init(void) {}
static void vio_cmo_sysfs_init(void) { }
#endif /* CONFIG_PPC_SMLPAR */
EXPORT_SYMBOL(vio_cmo_entitlement_update);
EXPORT_SYMBOL(vio_cmo_set_dev_desired);

static struct iommu_table *vio_build_iommu_table(struct vio_dev *dev)
{
	const unsigned char *dma_window;
	struct iommu_table *tbl;
	unsigned long offset, size;

	if (firmware_has_feature(FW_FEATURE_ISERIES))
		return vio_build_iommu_table_iseries(dev);

	dma_window = of_get_property(dev->dev.archdata.of_node,
				  "ibm,my-dma-window", NULL);
	if (!dma_window)
		return NULL;

	tbl = kmalloc(sizeof(*tbl), GFP_KERNEL);
	if (tbl == NULL)
		return NULL;

	of_parse_dma_window(dev->dev.archdata.of_node, dma_window,
			    &tbl->it_index, &offset, &size);

	/* TCE table size - measured in tce entries */
	tbl->it_size = size >> IOMMU_PAGE_SHIFT;
	/* offset for VIO should always be 0 */
	tbl->it_offset = offset >> IOMMU_PAGE_SHIFT;
	tbl->it_busno = 0;
	tbl->it_type = TCE_VB;

	return iommu_init_table(tbl, -1);
}

/**
 * vio_match_device: - Tell if a VIO device has a matching
 *			VIO device id structure.
 * @ids:	array of VIO device id structures to search in
 * @dev:	the VIO device structure to match against
 *
 * Used by a driver to check whether a VIO device present in the
 * system is in its list of supported devices. Returns the matching
 * vio_device_id structure or NULL if there is no match.
 */
static const struct vio_device_id *vio_match_device(
		const struct vio_device_id *ids, const struct vio_dev *dev)
{
	while (ids->type[0] != '\0') {
		if ((strncmp(dev->type, ids->type, strlen(ids->type)) == 0) &&
		    of_device_is_compatible(dev->dev.archdata.of_node,
					 ids->compat))
			return ids;
		ids++;
	}
	return NULL;
}

/*
 * Convert from struct device to struct vio_dev and pass to driver.
 * dev->driver has already been set by generic code because vio_bus_match
 * succeeded.
 */
static int vio_bus_probe(struct device *dev)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	struct vio_driver *viodrv = to_vio_driver(dev->driver);
	const struct vio_device_id *id;
	int error = -ENODEV;

	if (!viodrv->probe)
		return error;

	id = vio_match_device(viodrv->id_table, viodev);
	if (id) {
		memset(&viodev->cmo, 0, sizeof(viodev->cmo));
		if (firmware_has_feature(FW_FEATURE_CMO)) {
			error = vio_cmo_bus_probe(viodev);
			if (error)
				return error;
		}
		error = viodrv->probe(viodev, id);
		if (error && firmware_has_feature(FW_FEATURE_CMO))
			vio_cmo_bus_remove(viodev);
	}

	return error;
}

/* convert from struct device to struct vio_dev and pass to driver. */
static int vio_bus_remove(struct device *dev)
{
	struct vio_dev *viodev = to_vio_dev(dev);
	struct vio_driver *viodrv = to_vio_driver(dev->driver);
	struct device *devptr;
	int ret = 1;

	/*
	 * Hold a reference to the device after the remove function is called
	 * to allow for CMO accounting cleanup for the device.
	 */
	devptr = get_device(dev);

	if (viodrv->remove)
		ret = viodrv->remove(viodev);

	if (!ret && firmware_has_feature(FW_FEATURE_CMO))
		vio_cmo_bus_remove(viodev);

	put_device(devptr);
	return ret;
}

/**
 * vio_register_driver: - Register a new vio driver
 * @drv:	The vio_driver structure to be registered.
 */
int vio_register_driver(struct vio_driver *viodrv)
{
	printk(KERN_DEBUG "%s: driver %s registering\n", __func__,
		viodrv->driver.name);

	/* fill in 'struct driver' fields */
	viodrv->driver.bus = &vio_bus_type;

	return driver_register(&viodrv->driver);
}
EXPORT_SYMBOL(vio_register_driver);

/**
 * vio_unregister_driver - Remove registration of vio driver.
 * @driver:	The vio_driver struct to be removed form registration
 */
void vio_unregister_driver(struct vio_driver *viodrv)
{
	driver_unregister(&viodrv->driver);
}
EXPORT_SYMBOL(vio_unregister_driver);

/* vio_dev refcount hit 0 */
static void __devinit vio_dev_release(struct device *dev)
{
	/* XXX should free TCE table */
	of_node_put(dev->archdata.of_node);
	kfree(to_vio_dev(dev));
}

/**
 * vio_register_device_node: - Register a new vio device.
 * @of_node:	The OF node for this device.
 *
 * Creates and initializes a vio_dev structure from the data in
 * of_node and adds it to the list of virtual devices.
 * Returns a pointer to the created vio_dev or NULL if node has
 * NULL device_type or compatible fields.
 */
struct vio_dev *vio_register_device_node(struct device_node *of_node)
{
	struct vio_dev *viodev;
	const unsigned int *unit_address;

	/* we need the 'device_type' property, in order to match with drivers */
	if (of_node->type == NULL) {
		printk(KERN_WARNING "%s: node %s missing 'device_type'\n",
				__func__,
				of_node->name ? of_node->name : "<unknown>");
		return NULL;
	}

	unit_address = of_get_property(of_node, "reg", NULL);
	if (unit_address == NULL) {
		printk(KERN_WARNING "%s: node %s missing 'reg'\n",
				__func__,
				of_node->name ? of_node->name : "<unknown>");
		return NULL;
	}

	/* allocate a vio_dev for this node */
	viodev = kzalloc(sizeof(struct vio_dev), GFP_KERNEL);
	if (viodev == NULL)
		return NULL;

	viodev->irq = irq_of_parse_and_map(of_node, 0);

	dev_set_name(&viodev->dev, "%x", *unit_address);
	viodev->name = of_node->name;
	viodev->type = of_node->type;
	viodev->unit_address = *unit_address;
	if (firmware_has_feature(FW_FEATURE_ISERIES)) {
		unit_address = of_get_property(of_node,
				"linux,unit_address", NULL);
		if (unit_address != NULL)
			viodev->unit_address = *unit_address;
	}
	viodev->dev.archdata.of_node = of_node_get(of_node);

	if (firmware_has_feature(FW_FEATURE_CMO))
		vio_cmo_set_dma_ops(viodev);
	else
		viodev->dev.archdata.dma_ops = &dma_iommu_ops;
	set_iommu_table_base(&viodev->dev, vio_build_iommu_table(viodev));
	set_dev_node(&viodev->dev, of_node_to_nid(of_node));

	/* init generic 'struct device' fields: */
	viodev->dev.parent = &vio_bus_device.dev;
	viodev->dev.bus = &vio_bus_type;
	viodev->dev.release = vio_dev_release;

	/* register with generic device framework */
	if (device_register(&viodev->dev)) {
		printk(KERN_ERR "%s: failed to register device %s\n",
				__func__, dev_name(&viodev->dev));
		/* XXX free TCE table */
		kfree(viodev);
		return NULL;
	}

	return viodev;
}
EXPORT_SYMBOL(vio_register_device_node);

/**
 * vio_bus_init: - Initialize the virtual IO bus
 */
static int __init vio_bus_init(void)
{
	int err;
	struct device_node *node_vroot;

	if (firmware_has_feature(FW_FEATURE_CMO))
		vio_cmo_sysfs_init();

	err = bus_register(&vio_bus_type);
	if (err) {
		printk(KERN_ERR "failed to register VIO bus\n");
		return err;
	}

	/*
	 * The fake parent of all vio devices, just to give us
	 * a nice directory
	 */
	err = device_register(&vio_bus_device.dev);
	if (err) {
		printk(KERN_WARNING "%s: device_register returned %i\n",
				__func__, err);
		return err;
	}

	if (firmware_has_feature(FW_FEATURE_CMO))
		vio_cmo_bus_init();

	node_vroot = of_find_node_by_name(NULL, "vdevice");
	if (node_vroot) {
		struct device_node *of_node;

		/*
		 * Create struct vio_devices for each virtual device in
		 * the device tree. Drivers will associate with them later.
		 */
		for (of_node = node_vroot->child; of_node != NULL;
				of_node = of_node->sibling)
			vio_register_device_node(of_node);
		of_node_put(node_vroot);
	}

	return 0;
}
__initcall(vio_bus_init);

static ssize_t name_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%s\n", to_vio_dev(dev)->name);
}

static ssize_t devspec_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct device_node *of_node = dev->archdata.of_node;

	return sprintf(buf, "%s\n", of_node ? of_node->full_name : "none");
}

static struct device_attribute vio_dev_attrs[] = {
	__ATTR_RO(name),
	__ATTR_RO(devspec),
	__ATTR_NULL
};

void __devinit vio_unregister_device(struct vio_dev *viodev)
{
	device_unregister(&viodev->dev);
}
EXPORT_SYMBOL(vio_unregister_device);

static int vio_bus_match(struct device *dev, struct device_driver *drv)
{
	const struct vio_dev *vio_dev = to_vio_dev(dev);
	struct vio_driver *vio_drv = to_vio_driver(drv);
	const struct vio_device_id *ids = vio_drv->id_table;

	return (ids != NULL) && (vio_match_device(ids, vio_dev) != NULL);
}

static int vio_hotplug(struct device *dev, struct kobj_uevent_env *env)
{
	const struct vio_dev *vio_dev = to_vio_dev(dev);
	struct device_node *dn;
	const char *cp;

	dn = dev->archdata.of_node;
	if (!dn)
		return -ENODEV;
	cp = of_get_property(dn, "compatible", NULL);
	if (!cp)
		return -ENODEV;

	add_uevent_var(env, "MODALIAS=vio:T%sS%s", vio_dev->type, cp);
	return 0;
}

static struct bus_type vio_bus_type = {
	.name = "vio",
	.dev_attrs = vio_dev_attrs,
	.uevent = vio_hotplug,
	.match = vio_bus_match,
	.probe = vio_bus_probe,
	.remove = vio_bus_remove,
};

/**
 * vio_get_attribute: - get attribute for virtual device
 * @vdev:	The vio device to get property.
 * @which:	The property/attribute to be extracted.
 * @length:	Pointer to length of returned data size (unused if NULL).
 *
 * Calls prom.c's of_get_property() to return the value of the
 * attribute specified by @which
*/
const void *vio_get_attribute(struct vio_dev *vdev, char *which, int *length)
{
	return of_get_property(vdev->dev.archdata.of_node, which, length);
}
EXPORT_SYMBOL(vio_get_attribute);

#ifdef CONFIG_PPC_PSERIES
/* vio_find_name() - internal because only vio.c knows how we formatted the
 * kobject name
 */
static struct vio_dev *vio_find_name(const char *name)
{
	struct device *found;

	found = bus_find_device_by_name(&vio_bus_type, NULL, name);
	if (!found)
		return NULL;

	return to_vio_dev(found);
}

/**
 * vio_find_node - find an already-registered vio_dev
 * @vnode: device_node of the virtual device we're looking for
 */
struct vio_dev *vio_find_node(struct device_node *vnode)
{
	const uint32_t *unit_address;
	char kobj_name[20];

	/* construct the kobject name from the device node */
	unit_address = of_get_property(vnode, "reg", NULL);
	if (!unit_address)
		return NULL;
	snprintf(kobj_name, sizeof(kobj_name), "%x", *unit_address);

	return vio_find_name(kobj_name);
}
EXPORT_SYMBOL(vio_find_node);

int vio_enable_interrupts(struct vio_dev *dev)
{
	int rc = h_vio_signal(dev->unit_address, VIO_IRQ_ENABLE);
	if (rc != H_SUCCESS)
		printk(KERN_ERR "vio: Error 0x%x enabling interrupts\n", rc);
	return rc;
}
EXPORT_SYMBOL(vio_enable_interrupts);

int vio_disable_interrupts(struct vio_dev *dev)
{
	int rc = h_vio_signal(dev->unit_address, VIO_IRQ_DISABLE);
	if (rc != H_SUCCESS)
		printk(KERN_ERR "vio: Error 0x%x disabling interrupts\n", rc);
	return rc;
}
EXPORT_SYMBOL(vio_disable_interrupts);
#endif /* CONFIG_PPC_PSERIES */