summaryrefslogtreecommitdiff
path: root/Documentation/ioctl/hdio.rst
blob: e822e3dff1769bd952c390f2f6fa4e4dd28b1a33 (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
==============================
Summary of `HDIO_` ioctl calls
==============================

- Edward A. Falk <efalk@google.com>

November, 2004

This document attempts to describe the ioctl(2) calls supported by
the HD/IDE layer.  These are by-and-large implemented (as of Linux 2.6)
in drivers/ide/ide.c and drivers/block/scsi_ioctl.c

ioctl values are listed in <linux/hdreg.h>.  As of this writing, they
are as follows:

    ioctls that pass argument pointers to user space:

	=======================	=======================================
	HDIO_GETGEO		get device geometry
	HDIO_GET_UNMASKINTR	get current unmask setting
	HDIO_GET_MULTCOUNT	get current IDE blockmode setting
	HDIO_GET_QDMA		get use-qdma flag
	HDIO_SET_XFER		set transfer rate via proc
	HDIO_OBSOLETE_IDENTITY	OBSOLETE, DO NOT USE
	HDIO_GET_KEEPSETTINGS	get keep-settings-on-reset flag
	HDIO_GET_32BIT		get current io_32bit setting
	HDIO_GET_NOWERR		get ignore-write-error flag
	HDIO_GET_DMA		get use-dma flag
	HDIO_GET_NICE		get nice flags
	HDIO_GET_IDENTITY	get IDE identification info
	HDIO_GET_WCACHE		get write cache mode on|off
	HDIO_GET_ACOUSTIC	get acoustic value
	HDIO_GET_ADDRESS	get sector addressing mode
	HDIO_GET_BUSSTATE	get the bus state of the hwif
	HDIO_TRISTATE_HWIF	execute a channel tristate
	HDIO_DRIVE_RESET	execute a device reset
	HDIO_DRIVE_TASKFILE	execute raw taskfile
	HDIO_DRIVE_TASK		execute task and special drive command
	HDIO_DRIVE_CMD		execute a special drive command
	HDIO_DRIVE_CMD_AEB	HDIO_DRIVE_TASK
	=======================	=======================================

    ioctls that pass non-pointer values:

	=======================	=======================================
	HDIO_SET_MULTCOUNT	change IDE blockmode
	HDIO_SET_UNMASKINTR	permit other irqs during I/O
	HDIO_SET_KEEPSETTINGS	keep ioctl settings on reset
	HDIO_SET_32BIT		change io_32bit flags
	HDIO_SET_NOWERR		change ignore-write-error flag
	HDIO_SET_DMA		change use-dma flag
	HDIO_SET_PIO_MODE	reconfig interface to new speed
	HDIO_SCAN_HWIF		register and (re)scan interface
	HDIO_SET_NICE		set nice flags
	HDIO_UNREGISTER_HWIF	unregister interface
	HDIO_SET_WCACHE		change write cache enable-disable
	HDIO_SET_ACOUSTIC	change acoustic behavior
	HDIO_SET_BUSSTATE	set the bus state of the hwif
	HDIO_SET_QDMA		change use-qdma flag
	HDIO_SET_ADDRESS	change lba addressing modes

	HDIO_SET_IDE_SCSI	Set scsi emulation mode on/off
	HDIO_SET_SCSI_IDE	not implemented yet
	=======================	=======================================


The information that follows was determined from reading kernel source
code.  It is likely that some corrections will be made over time.

------------------------------------------------------------------------------

General:

	Unless otherwise specified, all ioctl calls return 0 on success
	and -1 with errno set to an appropriate value on error.

	Unless otherwise specified, all ioctl calls return -1 and set
	errno to EFAULT on a failed attempt to copy data to or from user
	address space.

	Unless otherwise specified, all data structures and constants
	are defined in <linux/hdreg.h>

------------------------------------------------------------------------------

HDIO_GETGEO
	get device geometry


	usage::

	  struct hd_geometry geom;

	  ioctl(fd, HDIO_GETGEO, &geom);


	inputs:
		none



	outputs:
		hd_geometry structure containing:


	    =========	==================================
	    heads	number of heads
	    sectors	number of sectors/track
	    cylinders	number of cylinders, mod 65536
	    start	starting sector of this partition.
	    =========	==================================


	error returns:
	  - EINVAL

			if the device is not a disk drive or floppy drive,
			or if the user passes a null pointer


	notes:
		Not particularly useful with modern disk drives, whose geometry
		is a polite fiction anyway.  Modern drives are addressed
		purely by sector number nowadays (lba addressing), and the
		drive geometry is an abstraction which is actually subject
		to change.  Currently (as of Nov 2004), the geometry values
		are the "bios" values -- presumably the values the drive had
		when Linux first booted.

		In addition, the cylinders field of the hd_geometry is an
		unsigned short, meaning that on most architectures, this
		ioctl will not return a meaningful value on drives with more
		than 65535 tracks.

		The start field is unsigned long, meaning that it will not
		contain a meaningful value for disks over 219 Gb in size.




HDIO_GET_UNMASKINTR
	get current unmask setting


	usage::

	  long val;

	  ioctl(fd, HDIO_GET_UNMASKINTR, &val);

	inputs:
		none



	outputs:
		The value of the drive's current unmask setting





HDIO_SET_UNMASKINTR
	permit other irqs during I/O


	usage::

	  unsigned long val;

	  ioctl(fd, HDIO_SET_UNMASKINTR, val);

	inputs:
		New value for unmask flag



	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 1]
	  - EBUSY	Controller busy




HDIO_GET_MULTCOUNT
	get current IDE blockmode setting


	usage::

	  long val;

	  ioctl(fd, HDIO_GET_MULTCOUNT, &val);

	inputs:
		none



	outputs:
		The value of the current IDE block mode setting.  This
		controls how many sectors the drive will transfer per
		interrupt.



HDIO_SET_MULTCOUNT
	change IDE blockmode


	usage::

	  int val;

	  ioctl(fd, HDIO_SET_MULTCOUNT, val);

	inputs:
		New value for IDE block mode setting.  This controls how many
		sectors the drive will transfer per interrupt.

	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range supported by disk.
	  - EBUSY	Controller busy or blockmode already set.
	  - EIO		Drive did not accept new block mode.

	notes:
	  Source code comments read::

	    This is tightly woven into the driver->do_special cannot
	    touch.  DON'T do it again until a total personality rewrite
	    is committed.

	  If blockmode has already been set, this ioctl will fail with
	  -EBUSY



HDIO_GET_QDMA
	get use-qdma flag


	Not implemented, as of 2.6.8.1



HDIO_SET_XFER
	set transfer rate via proc


	Not implemented, as of 2.6.8.1



HDIO_OBSOLETE_IDENTITY
	OBSOLETE, DO NOT USE


	Same as HDIO_GET_IDENTITY (see below), except that it only
	returns the first 142 bytes of drive identity information.



HDIO_GET_IDENTITY
	get IDE identification info


	usage::

	  unsigned char identity[512];

	  ioctl(fd, HDIO_GET_IDENTITY, identity);

	inputs:
		none



	outputs:
		ATA drive identity information.  For full description, see
		the IDENTIFY DEVICE and IDENTIFY PACKET DEVICE commands in
		the ATA specification.

	error returns:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - ENOMSG	IDENTIFY DEVICE information not available

	notes:
		Returns information that was obtained when the drive was
		probed.  Some of this information is subject to change, and
		this ioctl does not re-probe the drive to update the
		information.

		This information is also available from /proc/ide/hdX/identify



HDIO_GET_KEEPSETTINGS
	get keep-settings-on-reset flag


	usage::

	  long val;

	  ioctl(fd, HDIO_GET_KEEPSETTINGS, &val);

	inputs:
		none



	outputs:
		The value of the current "keep settings" flag



	notes:
		When set, indicates that kernel should restore settings
		after a drive reset.



HDIO_SET_KEEPSETTINGS
	keep ioctl settings on reset


	usage::

	  long val;

	  ioctl(fd, HDIO_SET_KEEPSETTINGS, val);

	inputs:
		New value for keep_settings flag



	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 1]
	  - EBUSY		Controller busy



HDIO_GET_32BIT
	get current io_32bit setting


	usage::

	  long val;

	  ioctl(fd, HDIO_GET_32BIT, &val);

	inputs:
		none



	outputs:
		The value of the current io_32bit setting



	notes:
		0=16-bit, 1=32-bit, 2,3 = 32bit+sync





HDIO_GET_NOWERR
	get ignore-write-error flag


	usage::

	  long val;

	  ioctl(fd, HDIO_GET_NOWERR, &val);

	inputs:
		none



	outputs:
		The value of the current ignore-write-error flag





HDIO_GET_DMA
	get use-dma flag


	usage::

	  long val;

	  ioctl(fd, HDIO_GET_DMA, &val);

	inputs:
		none



	outputs:
		The value of the current use-dma flag





HDIO_GET_NICE
	get nice flags


	usage::

	  long nice;

	  ioctl(fd, HDIO_GET_NICE, &nice);

	inputs:
		none



	outputs:
		The drive's "nice" values.



	notes:
		Per-drive flags which determine when the system will give more
		bandwidth to other devices sharing the same IDE bus.

		See <linux/hdreg.h>, near symbol IDE_NICE_DSC_OVERLAP.




HDIO_SET_NICE
	set nice flags


	usage::

	  unsigned long nice;

	  ...
	  ioctl(fd, HDIO_SET_NICE, nice);

	inputs:
		bitmask of nice flags.



	outputs:
		none



	error returns:
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EPERM	Flags other than DSC_OVERLAP and NICE_1 set.
	  - EPERM	DSC_OVERLAP specified but not supported by drive

	notes:
		This ioctl sets the DSC_OVERLAP and NICE_1 flags from values
		provided by the user.

		Nice flags are listed in <linux/hdreg.h>, starting with
		IDE_NICE_DSC_OVERLAP.  These values represent shifts.





HDIO_GET_WCACHE
	get write cache mode on|off


	usage::

	  long val;

	  ioctl(fd, HDIO_GET_WCACHE, &val);

	inputs:
		none



	outputs:
		The value of the current write cache mode





HDIO_GET_ACOUSTIC
	get acoustic value


	usage::

	  long val;

	  ioctl(fd, HDIO_GET_ACOUSTIC, &val);

	inputs:
		none



	outputs:
		The value of the current acoustic settings



	notes:
		See HDIO_SET_ACOUSTIC





HDIO_GET_ADDRESS
	usage::


	  long val;

	  ioctl(fd, HDIO_GET_ADDRESS, &val);

	inputs:
		none



	outputs:
		The value of the current addressing mode:

	    =  ===================
	    0  28-bit
	    1  48-bit
	    2  48-bit doing 28-bit
	    3  64-bit
	    =  ===================



HDIO_GET_BUSSTATE
	get the bus state of the hwif


	usage::

	  long state;

	  ioctl(fd, HDIO_SCAN_HWIF, &state);

	inputs:
		none



	outputs:
		Current power state of the IDE bus.  One of BUSSTATE_OFF,
		BUSSTATE_ON, or BUSSTATE_TRISTATE

	error returns:
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN




HDIO_SET_BUSSTATE
	set the bus state of the hwif


	usage::

	  int state;

	  ...
	  ioctl(fd, HDIO_SCAN_HWIF, state);

	inputs:
		Desired IDE power state.  One of BUSSTATE_OFF, BUSSTATE_ON,
		or BUSSTATE_TRISTATE

	outputs:
		none



	error returns:
	  - EACCES	Access denied:  requires CAP_SYS_RAWIO
	  - EOPNOTSUPP	Hardware interface does not support bus power control




HDIO_TRISTATE_HWIF
	execute a channel tristate


	Not implemented, as of 2.6.8.1.  See HDIO_SET_BUSSTATE



HDIO_DRIVE_RESET
	execute a device reset


	usage::

	  int args[3]

	  ...
	  ioctl(fd, HDIO_DRIVE_RESET, args);

	inputs:
		none



	outputs:
		none



	error returns:
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - ENXIO	No such device:	phy dead or ctl_addr == 0
	  - EIO		I/O error:	reset timed out or hardware error

	notes:

	  - Execute a reset on the device as soon as the current IO
	    operation has completed.

	  - Executes an ATAPI soft reset if applicable, otherwise
	    executes an ATA soft reset on the controller.



HDIO_DRIVE_TASKFILE
	execute raw taskfile


	Note:
		If you don't have a copy of the ANSI ATA specification
		handy, you should probably ignore this ioctl.

	- Execute an ATA disk command directly by writing the "taskfile"
	  registers of the drive.  Requires ADMIN and RAWIO access
	  privileges.

	usage::

	  struct {

	    ide_task_request_t req_task;
	    u8 outbuf[OUTPUT_SIZE];
	    u8 inbuf[INPUT_SIZE];
	  } task;
	  memset(&task.req_task, 0, sizeof(task.req_task));
	  task.req_task.out_size = sizeof(task.outbuf);
	  task.req_task.in_size = sizeof(task.inbuf);
	  ...
	  ioctl(fd, HDIO_DRIVE_TASKFILE, &task);
	  ...

	inputs:

	  (See below for details on memory area passed to ioctl.)

	  ============	===================================================
	  io_ports[8]	values to be written to taskfile registers
	  hob_ports[8]	high-order bytes, for extended commands.
	  out_flags	flags indicating which registers are valid
	  in_flags	flags indicating which registers should be returned
	  data_phase	see below
	  req_cmd	command type to be executed
	  out_size	size of output buffer
	  outbuf	buffer of data to be transmitted to disk
	  inbuf		buffer of data to be received from disk (see [1])
	  ============	===================================================

	outputs:

	  ===========	====================================================
	  io_ports[]	values returned in the taskfile registers
	  hob_ports[]	high-order bytes, for extended commands.
	  out_flags	flags indicating which registers are valid (see [2])
	  in_flags	flags indicating which registers should be returned
	  outbuf	buffer of data to be transmitted to disk (see [1])
	  inbuf		buffer of data to be received from disk
	  ===========	====================================================

	error returns:
	  - EACCES	CAP_SYS_ADMIN or CAP_SYS_RAWIO privilege not set.
	  - ENOMSG	Device is not a disk drive.
	  - ENOMEM	Unable to allocate memory for task
	  - EFAULT	req_cmd == TASKFILE_IN_OUT (not implemented as of 2.6.8)
	  - EPERM

			req_cmd == TASKFILE_MULTI_OUT and drive
			multi-count not yet set.
	  - EIO		Drive failed the command.

	notes:

	  [1] READ THE FOLLOWING NOTES *CAREFULLY*.  THIS IOCTL IS
	  FULL OF GOTCHAS.  Extreme caution should be used with using
	  this ioctl.  A mistake can easily corrupt data or hang the
	  system.

	  [2] Both the input and output buffers are copied from the
	  user and written back to the user, even when not used.

	  [3] If one or more bits are set in out_flags and in_flags is
	  zero, the following values are used for in_flags.all and
	  written back into in_flags on completion.

	   * IDE_TASKFILE_STD_IN_FLAGS | (IDE_HOB_STD_IN_FLAGS << 8)
	     if LBA48 addressing is enabled for the drive
	   * IDE_TASKFILE_STD_IN_FLAGS
	     if CHS/LBA28

	  The association between in_flags.all and each enable
	  bitfield flips depending on endianness; fortunately, TASKFILE
	  only uses inflags.b.data bit and ignores all other bits.
	  The end result is that, on any endian machines, it has no
	  effect other than modifying in_flags on completion.

	  [4] The default value of SELECT is (0xa0|DEV_bit|LBA_bit)
	  except for four drives per port chipsets.  For four drives
	  per port chipsets, it's (0xa0|DEV_bit|LBA_bit) for the first
	  pair and (0x80|DEV_bit|LBA_bit) for the second pair.

	  [5] The argument to the ioctl is a pointer to a region of
	  memory containing a ide_task_request_t structure, followed
	  by an optional buffer of data to be transmitted to the
	  drive, followed by an optional buffer to receive data from
	  the drive.

	  Command is passed to the disk drive via the ide_task_request_t
	  structure, which contains these fields:

	    ============	===============================================
	    io_ports[8]		values for the taskfile registers
	    hob_ports[8]	high-order bytes, for extended commands
	    out_flags		flags indicating which entries in the
				io_ports[] and hob_ports[] arrays
				contain valid values.  Type ide_reg_valid_t.
	    in_flags		flags indicating which entries in the
				io_ports[] and hob_ports[] arrays
				are expected to contain valid values
				on return.
	    data_phase		See below
	    req_cmd		Command type, see below
	    out_size		output (user->drive) buffer size, bytes
	    in_size		input (drive->user) buffer size, bytes
	    ============	===============================================

	  When out_flags is zero, the following registers are loaded.

	    ============	===============================================
	    HOB_FEATURE		If the drive supports LBA48
	    HOB_NSECTOR		If the drive supports LBA48
	    HOB_SECTOR		If the drive supports LBA48
	    HOB_LCYL		If the drive supports LBA48
	    HOB_HCYL		If the drive supports LBA48
	    FEATURE
	    NSECTOR
	    SECTOR
	    LCYL
	    HCYL
	    SELECT		First, masked with 0xE0 if LBA48, 0xEF
				otherwise; then, or'ed with the default
				value of SELECT.
	    ============	===============================================

	  If any bit in out_flags is set, the following registers are loaded.

	    ============	===============================================
	    HOB_DATA		If out_flags.b.data is set.  HOB_DATA will
				travel on DD8-DD15 on little endian machines
				and on DD0-DD7 on big endian machines.
	    DATA		If out_flags.b.data is set.  DATA will
				travel on DD0-DD7 on little endian machines
				and on DD8-DD15 on big endian machines.
	    HOB_NSECTOR		If out_flags.b.nsector_hob is set
	    HOB_SECTOR		If out_flags.b.sector_hob is set
	    HOB_LCYL		If out_flags.b.lcyl_hob is set
	    HOB_HCYL		If out_flags.b.hcyl_hob is set
	    FEATURE		If out_flags.b.feature is set
	    NSECTOR		If out_flags.b.nsector is set
	    SECTOR		If out_flags.b.sector is set
	    LCYL		If out_flags.b.lcyl is set
	    HCYL		If out_flags.b.hcyl is set
	    SELECT		Or'ed with the default value of SELECT and
				loaded regardless of out_flags.b.select.
	    ============	===============================================

	  Taskfile registers are read back from the drive into
	  {io|hob}_ports[] after the command completes iff one of the
	  following conditions is met; otherwise, the original values
	  will be written back, unchanged.

	    1. The drive fails the command (EIO).
	    2. One or more than one bits are set in out_flags.
	    3. The requested data_phase is TASKFILE_NO_DATA.

	    ============	===============================================
	    HOB_DATA		If in_flags.b.data is set.  It will contain
				DD8-DD15 on little endian machines and
				DD0-DD7 on big endian machines.
	    DATA		If in_flags.b.data is set.  It will contain
				DD0-DD7 on little endian machines and
				DD8-DD15 on big endian machines.
	    HOB_FEATURE		If the drive supports LBA48
	    HOB_NSECTOR		If the drive supports LBA48
	    HOB_SECTOR		If the drive supports LBA48
	    HOB_LCYL		If the drive supports LBA48
	    HOB_HCYL		If the drive supports LBA48
	    NSECTOR
	    SECTOR
	    LCYL
	    HCYL
	    ============	===============================================

	  The data_phase field describes the data transfer to be
	  performed.  Value is one of:

	    ===================        ========================================
	    TASKFILE_IN
	    TASKFILE_MULTI_IN
	    TASKFILE_OUT
	    TASKFILE_MULTI_OUT
	    TASKFILE_IN_OUT
	    TASKFILE_IN_DMA
	    TASKFILE_IN_DMAQ		== IN_DMA (queueing not supported)
	    TASKFILE_OUT_DMA
	    TASKFILE_OUT_DMAQ		== OUT_DMA (queueing not supported)
	    TASKFILE_P_IN		unimplemented
	    TASKFILE_P_IN_DMA		unimplemented
	    TASKFILE_P_IN_DMAQ		unimplemented
	    TASKFILE_P_OUT		unimplemented
	    TASKFILE_P_OUT_DMA		unimplemented
	    TASKFILE_P_OUT_DMAQ		unimplemented
	    ===================        ========================================

	  The req_cmd field classifies the command type.  It may be
	  one of:

	    ========================    =======================================
	    IDE_DRIVE_TASK_NO_DATA
	    IDE_DRIVE_TASK_SET_XFER	unimplemented
	    IDE_DRIVE_TASK_IN
	    IDE_DRIVE_TASK_OUT		unimplemented
	    IDE_DRIVE_TASK_RAW_WRITE
	    ========================    =======================================

	  [6] Do not access {in|out}_flags->all except for resetting
	  all the bits.  Always access individual bit fields.  ->all
	  value will flip depending on endianness.  For the same
	  reason, do not use IDE_{TASKFILE|HOB}_STD_{OUT|IN}_FLAGS
	  constants defined in hdreg.h.



HDIO_DRIVE_CMD
	execute a special drive command


	Note:  If you don't have a copy of the ANSI ATA specification
	handy, you should probably ignore this ioctl.

	usage::

	  u8 args[4+XFER_SIZE];

	  ...
	  ioctl(fd, HDIO_DRIVE_CMD, args);

	inputs:
	    Commands other than WIN_SMART:

	    =======     =======
	    args[0]	COMMAND
	    args[1]	NSECTOR
	    args[2]	FEATURE
	    args[3]	NSECTOR
	    =======     =======

	    WIN_SMART:

	    =======     =======
	    args[0]	COMMAND
	    args[1]	SECTOR
	    args[2]	FEATURE
	    args[3]	NSECTOR
	    =======     =======

	outputs:
		args[] buffer is filled with register values followed by any


	  data returned by the disk.

	    ========	====================================================
	    args[0]	status
	    args[1]	error
	    args[2]	NSECTOR
	    args[3]	undefined
	    args[4+]	NSECTOR * 512 bytes of data returned by the command.
	    ========	====================================================

	error returns:
	  - EACCES	Access denied:  requires CAP_SYS_RAWIO
	  - ENOMEM	Unable to allocate memory for task
	  - EIO		Drive reports error

	notes:

	  [1] For commands other than WIN_SMART, args[1] should equal
	  args[3].  SECTOR, LCYL and HCYL are undefined.  For
	  WIN_SMART, 0x4f and 0xc2 are loaded into LCYL and HCYL
	  respectively.  In both cases SELECT will contain the default
	  value for the drive.  Please refer to HDIO_DRIVE_TASKFILE
	  notes for the default value of SELECT.

	  [2] If NSECTOR value is greater than zero and the drive sets
	  DRQ when interrupting for the command, NSECTOR * 512 bytes
	  are read from the device into the area following NSECTOR.
	  In the above example, the area would be
	  args[4..4+XFER_SIZE].  16bit PIO is used regardless of
	  HDIO_SET_32BIT setting.

	  [3] If COMMAND == WIN_SETFEATURES && FEATURE == SETFEATURES_XFER
	  && NSECTOR >= XFER_SW_DMA_0 && the drive supports any DMA
	  mode, IDE driver will try to tune the transfer mode of the
	  drive accordingly.



HDIO_DRIVE_TASK
	execute task and special drive command


	Note:  If you don't have a copy of the ANSI ATA specification
	handy, you should probably ignore this ioctl.

	usage::

	  u8 args[7];

	  ...
	  ioctl(fd, HDIO_DRIVE_TASK, args);

	inputs:
	    Taskfile register values:

	    =======	=======
	    args[0]	COMMAND
	    args[1]	FEATURE
	    args[2]	NSECTOR
	    args[3]	SECTOR
	    args[4]	LCYL
	    args[5]	HCYL
	    args[6]	SELECT
	    =======	=======

	outputs:
	    Taskfile register values:


	    =======	=======
	    args[0]	status
	    args[1]	error
	    args[2]	NSECTOR
	    args[3]	SECTOR
	    args[4]	LCYL
	    args[5]	HCYL
	    args[6]	SELECT
	    =======	=======

	error returns:
	  - EACCES	Access denied:  requires CAP_SYS_RAWIO
	  - ENOMEM	Unable to allocate memory for task
	  - ENOMSG	Device is not a disk drive.
	  - EIO		Drive failed the command.

	notes:

	  [1] DEV bit (0x10) of SELECT register is ignored and the
	  appropriate value for the drive is used.  All other bits
	  are used unaltered.



HDIO_DRIVE_CMD_AEB
	HDIO_DRIVE_TASK


	Not implemented, as of 2.6.8.1



HDIO_SET_32BIT
	change io_32bit flags


	usage::

	  int val;

	  ioctl(fd, HDIO_SET_32BIT, val);

	inputs:
		New value for io_32bit flag



	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 3]
	  - EBUSY	Controller busy




HDIO_SET_NOWERR
	change ignore-write-error flag


	usage::

	  int val;

	  ioctl(fd, HDIO_SET_NOWERR, val);

	inputs:
		New value for ignore-write-error flag.  Used for ignoring


	  WRERR_STAT

	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 1]
	  - EBUSY		Controller busy



HDIO_SET_DMA
	change use-dma flag


	usage::

	  long val;

	  ioctl(fd, HDIO_SET_DMA, val);

	inputs:
		New value for use-dma flag



	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 1]
	  - EBUSY	Controller busy



HDIO_SET_PIO_MODE
	reconfig interface to new speed


	usage::

	  long val;

	  ioctl(fd, HDIO_SET_PIO_MODE, val);

	inputs:
		New interface speed.



	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 255]
	  - EBUSY	Controller busy



HDIO_SCAN_HWIF
	register and (re)scan interface


	usage::

	  int args[3]

	  ...
	  ioctl(fd, HDIO_SCAN_HWIF, args);

	inputs:

	  =======	=========================
	  args[0]	io address to probe


	  args[1]	control address to probe
	  args[2]	irq number
	  =======	=========================

	outputs:
		none



	error returns:
	  - EACCES	Access denied:  requires CAP_SYS_RAWIO
	  - EIO		Probe failed.

	notes:
		This ioctl initializes the addresses and irq for a disk
		controller, probes for drives, and creates /proc/ide
		interfaces as appropriate.



HDIO_UNREGISTER_HWIF
	unregister interface


	usage::

	  int index;

	  ioctl(fd, HDIO_UNREGISTER_HWIF, index);

	inputs:
		index		index of hardware interface to unregister



	outputs:
		none



	error returns:
	  - EACCES	Access denied:  requires CAP_SYS_RAWIO

	notes:
		This ioctl removes a hardware interface from the kernel.

		Currently (2.6.8) this ioctl silently fails if any drive on
		the interface is busy.



HDIO_SET_WCACHE
	change write cache enable-disable


	usage::

	  int val;

	  ioctl(fd, HDIO_SET_WCACHE, val);

	inputs:
		New value for write cache enable



	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 1]
	  - EBUSY	Controller busy



HDIO_SET_ACOUSTIC
	change acoustic behavior


	usage::

	  int val;

	  ioctl(fd, HDIO_SET_ACOUSTIC, val);

	inputs:
		New value for drive acoustic settings



	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 254]
	  - EBUSY	Controller busy



HDIO_SET_QDMA
	change use-qdma flag


	Not implemented, as of 2.6.8.1



HDIO_SET_ADDRESS
	change lba addressing modes


	usage::

	  int val;

	  ioctl(fd, HDIO_SET_ADDRESS, val);

	inputs:
		New value for addressing mode

	    =   ===================
	    0   28-bit
	    1   48-bit
	    2   48-bit doing 28-bit
	    =   ===================

	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 2]
	  - EBUSY		Controller busy
	  - EIO		Drive does not support lba48 mode.


HDIO_SET_IDE_SCSI
	usage::


	  long val;

	  ioctl(fd, HDIO_SET_IDE_SCSI, val);

	inputs:
		New value for scsi emulation mode (?)



	outputs:
		none



	error return:
	  - EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EINVAL	value out of range [0 1]
	  - EBUSY	Controller busy



HDIO_SET_SCSI_IDE
	Not implemented, as of 2.6.8.1