aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/parport-lowlevel.txt
blob: 120eb20dbb09199afc1628a2ca1187812789bde9 (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
PARPORT interface documentation
-------------------------------

Time-stamp: <2000-02-24 13:30:20 twaugh>

Described here are the following functions:

Global functions:
  parport_register_driver
  parport_unregister_driver
  parport_enumerate
  parport_register_device
  parport_unregister_device
  parport_claim
  parport_claim_or_block
  parport_release
  parport_yield
  parport_yield_blocking
  parport_wait_peripheral
  parport_poll_peripheral
  parport_wait_event
  parport_negotiate
  parport_read
  parport_write
  parport_open
  parport_close
  parport_device_id
  parport_device_coords
  parport_find_class
  parport_find_device
  parport_set_timeout

Port functions (can be overridden by low-level drivers):
  SPP:
    port->ops->read_data
    port->ops->write_data
    port->ops->read_status
    port->ops->read_control
    port->ops->write_control
    port->ops->frob_control
    port->ops->enable_irq
    port->ops->disable_irq
    port->ops->data_forward
    port->ops->data_reverse

  EPP:
    port->ops->epp_write_data
    port->ops->epp_read_data
    port->ops->epp_write_addr
    port->ops->epp_read_addr

  ECP:
    port->ops->ecp_write_data
    port->ops->ecp_read_data
    port->ops->ecp_write_addr

  Other:
    port->ops->nibble_read_data
    port->ops->byte_read_data
    port->ops->compat_write_data

The parport subsystem comprises 'parport' (the core port-sharing
code), and a variety of low-level drivers that actually do the port
accesses.  Each low-level driver handles a particular style of port
(PC, Amiga, and so on).

The parport interface to the device driver author can be broken down
into global functions and port functions.

The global functions are mostly for communicating between the device
driver and the parport subsystem: acquiring a list of available ports,
claiming a port for exclusive use, and so on.  They also include
'generic' functions for doing standard things that will work on any
IEEE 1284-capable architecture.

The port functions are provided by the low-level drivers, although the
core parport module provides generic 'defaults' for some routines.
The port functions can be split into three groups: SPP, EPP, and ECP.

SPP (Standard Parallel Port) functions modify so-called 'SPP'
registers: data, status, and control.  The hardware may not actually
have registers exactly like that, but the PC does and this interface is
modelled after common PC implementations.  Other low-level drivers may
be able to emulate most of the functionality.

EPP (Enhanced Parallel Port) functions are provided for reading and
writing in IEEE 1284 EPP mode, and ECP (Extended Capabilities Port)
functions are used for IEEE 1284 ECP mode. (What about BECP? Does
anyone care?)

Hardware assistance for EPP and/or ECP transfers may or may not be
available, and if it is available it may or may not be used.  If
hardware is not used, the transfer will be software-driven.  In order
to cope with peripherals that only tenuously support IEEE 1284, a
low-level driver specific function is provided, for altering 'fudge
factors'.

GLOBAL FUNCTIONS
----------------

parport_register_driver - register a device driver with parport
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_driver {
	const char *name;
	void (*attach) (struct parport *);
	void (*detach) (struct parport *);
	struct parport_driver *next;
};
int parport_register_driver (struct parport_driver *driver);

DESCRIPTION

In order to be notified about parallel ports when they are detected,
parport_register_driver should be called.  Your driver will
immediately be notified of all ports that have already been detected,
and of each new port as low-level drivers are loaded.

A 'struct parport_driver' contains the textual name of your driver,
a pointer to a function to handle new ports, and a pointer to a
function to handle ports going away due to a low-level driver
unloading.  Ports will only be detached if they are not being used
(i.e. there are no devices registered on them).

The visible parts of the 'struct parport *' argument given to
attach/detach are:

struct parport
{
	struct parport *next; /* next parport in list */
	const char *name;     /* port's name */
	unsigned int modes;   /* bitfield of hardware modes */
	struct parport_device_info probe_info;
			      /* IEEE1284 info */
	int number;           /* parport index */
	struct parport_operations *ops;
	...
};

There are other members of the structure, but they should not be
touched.

The 'modes' member summarises the capabilities of the underlying
hardware.  It consists of flags which may be bitwise-ored together:

  PARPORT_MODE_PCSPP		IBM PC registers are available,
				i.e. functions that act on data,
				control and status registers are
				probably writing directly to the
				hardware.
  PARPORT_MODE_TRISTATE		The data drivers may be turned off.
				This allows the data lines to be used
				for reverse (peripheral to host)
				transfers.
  PARPORT_MODE_COMPAT		The hardware can assist with
				compatibility-mode (printer)
				transfers, i.e. compat_write_block.
  PARPORT_MODE_EPP		The hardware can assist with EPP
				transfers.
  PARPORT_MODE_ECP		The hardware can assist with ECP
				transfers.
  PARPORT_MODE_DMA		The hardware can use DMA, so you might
				want to pass ISA DMA-able memory
				(i.e. memory allocated using the
				GFP_DMA flag with kmalloc) to the
				low-level driver in order to take
				advantage of it.

There may be other flags in 'modes' as well.

The contents of 'modes' is advisory only.  For example, if the
hardware is capable of DMA, and PARPORT_MODE_DMA is in 'modes', it
doesn't necessarily mean that DMA will always be used when possible.
Similarly, hardware that is capable of assisting ECP transfers won't
necessarily be used.

RETURN VALUE

Zero on success, otherwise an error code.

ERRORS

None. (Can it fail? Why return int?)

EXAMPLE

static void lp_attach (struct parport *port)
{
	...
	private = kmalloc (...);
	dev[count++] = parport_register_device (...);
	...
}

static void lp_detach (struct parport *port)
{
	...
}

static struct parport_driver lp_driver = {
	"lp",
	lp_attach,
	lp_detach,
	NULL /* always put NULL here */
};

int lp_init (void)
{
	...
	if (parport_register_driver (&lp_driver)) {
		/* Failed; nothing we can do. */
		return -EIO;
	}
	...
}

SEE ALSO

parport_unregister_driver, parport_register_device, parport_enumerate

parport_unregister_driver - tell parport to forget about this driver
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_driver {
	const char *name;
	void (*attach) (struct parport *);
	void (*detach) (struct parport *);
	struct parport_driver *next;
};
void parport_unregister_driver (struct parport_driver *driver);

DESCRIPTION

This tells parport not to notify the device driver of new ports or of
ports going away.  Registered devices belonging to that driver are NOT
unregistered: parport_unregister_device must be used for each one.

EXAMPLE

void cleanup_module (void)
{
	...
	/* Stop notifications. */
	parport_unregister_driver (&lp_driver);

	/* Unregister devices. */
	for (i = 0; i < NUM_DEVS; i++)
		parport_unregister_device (dev[i]);
	...
}

SEE ALSO

parport_register_driver, parport_enumerate

parport_enumerate - retrieve a list of parallel ports (DEPRECATED)
-----------------

SYNOPSIS

#include <linux/parport.h>

struct parport *parport_enumerate (void);

DESCRIPTION

Retrieve the first of a list of valid parallel ports for this machine.
Successive parallel ports can be found using the 'struct parport
*next' element of the 'struct parport *' that is returned.  If 'next'
is NULL, there are no more parallel ports in the list.  The number of
ports in the list will not exceed PARPORT_MAX.

RETURN VALUE

A 'struct parport *' describing a valid parallel port for the machine,
or NULL if there are none.

ERRORS

This function can return NULL to indicate that there are no parallel
ports to use.

EXAMPLE

int detect_device (void)
{
	struct parport *port;

	for (port = parport_enumerate ();
	     port != NULL;
	     port = port->next) {
		/* Try to detect a device on the port... */
		...
             }
	}

	...
}

NOTES

parport_enumerate is deprecated; parport_register_driver should be
used instead.

SEE ALSO

parport_register_driver, parport_unregister_driver

parport_register_device - register to use a port
-----------------------

SYNOPSIS

#include <linux/parport.h>

typedef int (*preempt_func) (void *handle);
typedef void (*wakeup_func) (void *handle);
typedef int (*irq_func) (int irq, void *handle, struct pt_regs *);

struct pardevice *parport_register_device(struct parport *port,
                                          const char *name,
                                          preempt_func preempt,
                                          wakeup_func wakeup,
                                          irq_func irq,
                                          int flags,
                                          void *handle);

DESCRIPTION

Use this function to register your device driver on a parallel port
('port').  Once you have done that, you will be able to use
parport_claim and parport_release in order to use the port.

The ('name') argument is the name of the device that appears in /proc
filesystem. The string must be valid for the whole lifetime of the
device (until parport_unregister_device is called).

This function will register three callbacks into your driver:
'preempt', 'wakeup' and 'irq'.  Each of these may be NULL in order to
indicate that you do not want a callback.

When the 'preempt' function is called, it is because another driver
wishes to use the parallel port.  The 'preempt' function should return
non-zero if the parallel port cannot be released yet -- if zero is
returned, the port is lost to another driver and the port must be
re-claimed before use.

The 'wakeup' function is called once another driver has released the
port and no other driver has yet claimed it.  You can claim the
parallel port from within the 'wakeup' function (in which case the
claim is guaranteed to succeed), or choose not to if you don't need it
now.

If an interrupt occurs on the parallel port your driver has claimed,
the 'irq' function will be called. (Write something about shared
interrupts here.)

The 'handle' is a pointer to driver-specific data, and is passed to
the callback functions.

'flags' may be a bitwise combination of the following flags:

        Flag            Meaning
  PARPORT_DEV_EXCL	The device cannot share the parallel port at all.
			Use this only when absolutely necessary.

The typedefs are not actually defined -- they are only shown in order
to make the function prototype more readable.

The visible parts of the returned 'struct pardevice' are:

struct pardevice {
	struct parport *port;	/* Associated port */
	void *private;		/* Device driver's 'handle' */
	...
};

RETURN VALUE

A 'struct pardevice *': a handle to the registered parallel port
device that can be used for parport_claim, parport_release, etc.

ERRORS

A return value of NULL indicates that there was a problem registering
a device on that port.

EXAMPLE

static int preempt (void *handle)
{
	if (busy_right_now)
		return 1;

	must_reclaim_port = 1;
	return 0;
}

static void wakeup (void *handle)
{
	struct toaster *private = handle;
	struct pardevice *dev = private->dev;
	if (!dev) return; /* avoid races */

	if (want_port)
		parport_claim (dev);
}

static int toaster_detect (struct toaster *private, struct parport *port)
{
	private->dev = parport_register_device (port, "toaster", preempt,
					        wakeup, NULL, 0,
						private);
	if (!private->dev)
		/* Couldn't register with parport. */
		return -EIO;

	must_reclaim_port = 0;
	busy_right_now = 1;
	parport_claim_or_block (private->dev);
	...
	/* Don't need the port while the toaster warms up. */
	busy_right_now = 0;
	...
	busy_right_now = 1;
	if (must_reclaim_port) {
		parport_claim_or_block (private->dev);
		must_reclaim_port = 0;
	}
	...
}

SEE ALSO

parport_unregister_device, parport_claim

parport_unregister_device - finish using a port
-------------------------

SYNPOPSIS

#include <linux/parport.h>

void parport_unregister_device (struct pardevice *dev);

DESCRIPTION

This function is the opposite of parport_register_device.  After using
parport_unregister_device, 'dev' is no longer a valid device handle.

You should not unregister a device that is currently claimed, although
if you do it will be released automatically.

EXAMPLE

	...
	kfree (dev->private); /* before we lose the pointer */
	parport_unregister_device (dev);
	...

SEE ALSO

parport_unregister_driver

parport_claim, parport_claim_or_block - claim the parallel port for a device
-------------------------------------

SYNOPSIS

#include <linux/parport.h>

int parport_claim (struct pardevice *dev);
int parport_claim_or_block (struct pardevice *dev);

DESCRIPTION

These functions attempt to gain control of the parallel port on which
'dev' is registered.  'parport_claim' does not block, but
'parport_claim_or_block' may do. (Put something here about blocking
interruptibly or non-interruptibly.)

You should not try to claim a port that you have already claimed.

RETURN VALUE

A return value of zero indicates that the port was successfully
claimed, and the caller now has possession of the parallel port.

If 'parport_claim_or_block' blocks before returning successfully, the
return value is positive.

ERRORS

  -EAGAIN  The port is unavailable at the moment, but another attempt
           to claim it may succeed.

SEE ALSO

parport_release

parport_release - release the parallel port
---------------

SYNOPSIS

#include <linux/parport.h>

void parport_release (struct pardevice *dev);

DESCRIPTION

Once a parallel port device has been claimed, it can be released using
'parport_release'.  It cannot fail, but you should not release a
device that you do not have possession of.

EXAMPLE

static size_t write (struct pardevice *dev, const void *buf,
		     size_t len)
{
	...
	written = dev->port->ops->write_ecp_data (dev->port, buf,
						  len);
	parport_release (dev);
	...
}


SEE ALSO

change_mode, parport_claim, parport_claim_or_block, parport_yield

parport_yield, parport_yield_blocking - temporarily release a parallel port
-------------------------------------

SYNOPSIS

#include <linux/parport.h>

int parport_yield (struct pardevice *dev)
int parport_yield_blocking (struct pardevice *dev);

DESCRIPTION

When a driver has control of a parallel port, it may allow another
driver to temporarily 'borrow' it.  'parport_yield' does not block;
'parport_yield_blocking' may do.

RETURN VALUE

A return value of zero indicates that the caller still owns the port
and the call did not block.

A positive return value from 'parport_yield_blocking' indicates that
the caller still owns the port and the call blocked.

A return value of -EAGAIN indicates that the caller no longer owns the
port, and it must be re-claimed before use.

ERRORS

  -EAGAIN  Ownership of the parallel port was given away.

SEE ALSO

parport_release

parport_wait_peripheral - wait for status lines, up to 35ms
-----------------------

SYNOPSIS

#include <linux/parport.h>

int parport_wait_peripheral (struct parport *port,
			     unsigned char mask,
			     unsigned char val);

DESCRIPTION

Wait for the status lines in mask to match the values in val.

RETURN VALUE

 -EINTR  a signal is pending
      0  the status lines in mask have values in val
      1  timed out while waiting (35ms elapsed)

SEE ALSO

parport_poll_peripheral

parport_poll_peripheral - wait for status lines, in usec
-----------------------

SYNOPSIS

#include <linux/parport.h>

int parport_poll_peripheral (struct parport *port,
			     unsigned char mask,
			     unsigned char val,
			     int usec);

DESCRIPTION

Wait for the status lines in mask to match the values in val.

RETURN VALUE

 -EINTR  a signal is pending
      0  the status lines in mask have values in val
      1  timed out while waiting (usec microseconds have elapsed)

SEE ALSO

parport_wait_peripheral

parport_wait_event - wait for an event on a port
------------------

SYNOPSIS

#include <linux/parport.h>

int parport_wait_event (struct parport *port, signed long timeout)

DESCRIPTION

Wait for an event (e.g. interrupt) on a port.  The timeout is in
jiffies.

RETURN VALUE

      0  success
     <0  error (exit as soon as possible)
     >0  timed out

parport_negotiate - perform IEEE 1284 negotiation
-----------------

SYNOPSIS

#include <linux/parport.h>

int parport_negotiate (struct parport *, int mode);

DESCRIPTION

Perform IEEE 1284 negotiation.

RETURN VALUE

     0  handshake OK; IEEE 1284 peripheral and mode available
    -1  handshake failed; peripheral not compliant (or none present)
     1  handshake OK; IEEE 1284 peripheral present but mode not
        available

SEE ALSO

parport_read, parport_write

parport_read - read data from device
------------

SYNOPSIS

#include <linux/parport.h>

ssize_t parport_read (struct parport *, void *buf, size_t len);

DESCRIPTION

Read data from device in current IEEE 1284 transfer mode.  This only
works for modes that support reverse data transfer.

RETURN VALUE

If negative, an error code; otherwise the number of bytes transferred.

SEE ALSO

parport_write, parport_negotiate

parport_write - write data to device
-------------

SYNOPSIS

#include <linux/parport.h>

ssize_t parport_write (struct parport *, const void *buf, size_t len);

DESCRIPTION

Write data to device in current IEEE 1284 transfer mode.  This only
works for modes that support forward data transfer.

RETURN VALUE

If negative, an error code; otherwise the number of bytes transferred.

SEE ALSO

parport_read, parport_negotiate

parport_open - register device for particular device number
------------

SYNOPSIS

#include <linux/parport.h>

struct pardevice *parport_open (int devnum, const char *name,
			        int (*pf) (void *),
				void (*kf) (void *),
				void (*irqf) (int, void *,
					      struct pt_regs *),
				int flags, void *handle);

DESCRIPTION

This is like parport_register_device but takes a device number instead
of a pointer to a struct parport.

RETURN VALUE

See parport_register_device.  If no device is associated with devnum,
NULL is returned.

SEE ALSO

parport_register_device

parport_close - unregister device for particular device number
-------------

SYNOPSIS

#include <linux/parport.h>

void parport_close (struct pardevice *dev);

DESCRIPTION

This is the equivalent of parport_unregister_device for parport_open.

SEE ALSO

parport_unregister_device, parport_open

parport_device_id - obtain IEEE 1284 Device ID
-----------------

SYNOPSIS

#include <linux/parport.h>

ssize_t parport_device_id (int devnum, char *buffer, size_t len);

DESCRIPTION

Obtains the IEEE 1284 Device ID associated with a given device.

RETURN VALUE

If negative, an error code; otherwise, the number of bytes of buffer
that contain the device ID.  The format of the device ID is as
follows:

[length][ID]

The first two bytes indicate the inclusive length of the entire Device
ID, and are in big-endian order.  The ID is a sequence of pairs of the
form:

key:value;

NOTES

Many devices have ill-formed IEEE 1284 Device IDs.

SEE ALSO

parport_find_class, parport_find_device

parport_device_coords - convert device number to device coordinates
------------------

SYNOPSIS

#include <linux/parport.h>

int parport_device_coords (int devnum, int *parport, int *mux,
			   int *daisy);

DESCRIPTION

Convert between device number (zero-based) and device coordinates
(port, multiplexor, daisy chain address).

RETURN VALUE

Zero on success, in which case the coordinates are (*parport, *mux,
*daisy).

SEE ALSO

parport_open, parport_device_id

parport_find_class - find a device by its class
------------------

SYNOPSIS

#include <linux/parport.h>

typedef enum {
	PARPORT_CLASS_LEGACY = 0,       /* Non-IEEE1284 device */
	PARPORT_CLASS_PRINTER,
	PARPORT_CLASS_MODEM,
	PARPORT_CLASS_NET,
	PARPORT_CLASS_HDC,              /* Hard disk controller */
	PARPORT_CLASS_PCMCIA,
	PARPORT_CLASS_MEDIA,            /* Multimedia device */
	PARPORT_CLASS_FDC,              /* Floppy disk controller */
	PARPORT_CLASS_PORTS,
	PARPORT_CLASS_SCANNER,
	PARPORT_CLASS_DIGCAM,
	PARPORT_CLASS_OTHER,            /* Anything else */
	PARPORT_CLASS_UNSPEC,           /* No CLS field in ID */
	PARPORT_CLASS_SCSIADAPTER
} parport_device_class;

int parport_find_class (parport_device_class cls, int from);

DESCRIPTION

Find a device by class.  The search starts from device number from+1.

RETURN VALUE

The device number of the next device in that class, or -1 if no such
device exists.

NOTES

Example usage:

int devnum = -1;
while ((devnum = parport_find_class (PARPORT_CLASS_DIGCAM, devnum)) != -1) {
    struct pardevice *dev = parport_open (devnum, ...);
    ...
}

SEE ALSO

parport_find_device, parport_open, parport_device_id

parport_find_device - find a device by its class
------------------

SYNOPSIS

#include <linux/parport.h>

int parport_find_device (const char *mfg, const char *mdl, int from);

DESCRIPTION

Find a device by vendor and model.  The search starts from device
number from+1.

RETURN VALUE

The device number of the next device matching the specifications, or
-1 if no such device exists.

NOTES

Example usage:

int devnum = -1;
while ((devnum = parport_find_device ("IOMEGA", "ZIP+", devnum)) != -1) {
    struct pardevice *dev = parport_open (devnum, ...);
    ...
}

SEE ALSO

parport_find_class, parport_open, parport_device_id

parport_set_timeout - set the inactivity timeout
-------------------

SYNOPSIS

#include <linux/parport.h>

long parport_set_timeout (struct pardevice *dev, long inactivity);

DESCRIPTION

Set the inactivity timeout, in jiffies, for a registered device.  The
previous timeout is returned.

RETURN VALUE

The previous timeout, in jiffies.

NOTES

Some of the port->ops functions for a parport may take time, owing to
delays at the peripheral.  After the peripheral has not responded for
'inactivity' jiffies, a timeout will occur and the blocking function
will return.

A timeout of 0 jiffies is a special case: the function must do as much
as it can without blocking or leaving the hardware in an unknown
state.  If port operations are performed from within an interrupt
handler, for instance, a timeout of 0 jiffies should be used.

Once set for a registered device, the timeout will remain at the set
value until set again.

SEE ALSO

port->ops->xxx_read/write_yyy

PORT FUNCTIONS
--------------

The functions in the port->ops structure (struct parport_operations)
are provided by the low-level driver responsible for that port.

port->ops->read_data - read the data register
--------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	unsigned char (*read_data) (struct parport *port);
	...
};

DESCRIPTION

If port->modes contains the PARPORT_MODE_TRISTATE flag and the
PARPORT_CONTROL_DIRECTION bit in the control register is set, this
returns the value on the data pins.  If port->modes contains the
PARPORT_MODE_TRISTATE flag and the PARPORT_CONTROL_DIRECTION bit is
not set, the return value _may_ be the last value written to the data
register.  Otherwise the return value is undefined.

SEE ALSO

write_data, read_status, write_control

port->ops->write_data - write the data register
---------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	void (*write_data) (struct parport *port, unsigned char d);
	...
};

DESCRIPTION

Writes to the data register.  May have side-effects (a STROBE pulse,
for instance).

SEE ALSO

read_data, read_status, write_control

port->ops->read_status - read the status register
----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	unsigned char (*read_status) (struct parport *port);
	...
};

DESCRIPTION

Reads from the status register.  This is a bitmask:

- PARPORT_STATUS_ERROR (printer fault, "nFault")
- PARPORT_STATUS_SELECT (on-line, "Select")
- PARPORT_STATUS_PAPEROUT (no paper, "PError")
- PARPORT_STATUS_ACK (handshake, "nAck")
- PARPORT_STATUS_BUSY (busy, "Busy")

There may be other bits set.

SEE ALSO

read_data, write_data, write_control

port->ops->read_control - read the control register
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	unsigned char (*read_control) (struct parport *port);
	...
};

DESCRIPTION

Returns the last value written to the control register (either from
write_control or frob_control).  No port access is performed.

SEE ALSO

read_data, write_data, read_status, write_control

port->ops->write_control - write the control register
------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	void (*write_control) (struct parport *port, unsigned char s);
	...
};

DESCRIPTION

Writes to the control register. This is a bitmask:
                          _______
- PARPORT_CONTROL_STROBE (nStrobe)
                          _______
- PARPORT_CONTROL_AUTOFD (nAutoFd)
                        _____
- PARPORT_CONTROL_INIT (nInit)
                          _________
- PARPORT_CONTROL_SELECT (nSelectIn)

SEE ALSO

read_data, write_data, read_status, frob_control

port->ops->frob_control - write control register bits
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	unsigned char (*frob_control) (struct parport *port,
				       unsigned char mask,
				       unsigned char val);
	...
};

DESCRIPTION

This is equivalent to reading from the control register, masking out
the bits in mask, exclusive-or'ing with the bits in val, and writing
the result to the control register.

As some ports don't allow reads from the control port, a software copy
of its contents is maintained, so frob_control is in fact only one
port access.

SEE ALSO

read_data, write_data, read_status, write_control

port->ops->enable_irq - enable interrupt generation
---------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	void (*enable_irq) (struct parport *port);
	...
};

DESCRIPTION

The parallel port hardware is instructed to generate interrupts at
appropriate moments, although those moments are
architecture-specific.  For the PC architecture, interrupts are
commonly generated on the rising edge of nAck.

SEE ALSO

disable_irq

port->ops->disable_irq - disable interrupt generation
----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	void (*disable_irq) (struct parport *port);
	...
};

DESCRIPTION

The parallel port hardware is instructed not to generate interrupts.
The interrupt itself is not masked.

SEE ALSO

enable_irq

port->ops->data_forward - enable data drivers
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	void (*data_forward) (struct parport *port);
	...
};

DESCRIPTION

Enables the data line drivers, for 8-bit host-to-peripheral
communications.

SEE ALSO

data_reverse

port->ops->data_reverse - tristate the buffer
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	void (*data_reverse) (struct parport *port);
	...
};

DESCRIPTION

Places the data bus in a high impedance state, if port->modes has the
PARPORT_MODE_TRISTATE bit set.

SEE ALSO

data_forward

port->ops->epp_write_data - write EPP data
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*epp_write_data) (struct parport *port, const void *buf,
				  size_t len, int flags);
	...
};

DESCRIPTION

Writes data in EPP mode, and returns the number of bytes written.

The 'flags' parameter may be one or more of the following,
bitwise-or'ed together:

PARPORT_EPP_FAST	Use fast transfers. Some chips provide 16-bit and
			32-bit registers.  However, if a transfer
			times out, the return value may be unreliable.

SEE ALSO

epp_read_data, epp_write_addr, epp_read_addr

port->ops->epp_read_data - read EPP data
------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*epp_read_data) (struct parport *port, void *buf,
				 size_t len, int flags);
	...
};

DESCRIPTION

Reads data in EPP mode, and returns the number of bytes read.

The 'flags' parameter may be one or more of the following,
bitwise-or'ed together:

PARPORT_EPP_FAST	Use fast transfers. Some chips provide 16-bit and
			32-bit registers.  However, if a transfer
			times out, the return value may be unreliable.

SEE ALSO

epp_write_data, epp_write_addr, epp_read_addr

port->ops->epp_write_addr - write EPP address
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*epp_write_addr) (struct parport *port,
				  const void *buf, size_t len, int flags);
	...
};

DESCRIPTION

Writes EPP addresses (8 bits each), and returns the number written.

The 'flags' parameter may be one or more of the following,
bitwise-or'ed together:

PARPORT_EPP_FAST	Use fast transfers. Some chips provide 16-bit and
			32-bit registers.  However, if a transfer
			times out, the return value may be unreliable.

(Does PARPORT_EPP_FAST make sense for this function?)

SEE ALSO

epp_write_data, epp_read_data, epp_read_addr

port->ops->epp_read_addr - read EPP address
------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*epp_read_addr) (struct parport *port, void *buf,
				 size_t len, int flags);
	...
};

DESCRIPTION

Reads EPP addresses (8 bits each), and returns the number read.

The 'flags' parameter may be one or more of the following,
bitwise-or'ed together:

PARPORT_EPP_FAST	Use fast transfers. Some chips provide 16-bit and
			32-bit registers.  However, if a transfer
			times out, the return value may be unreliable.

(Does PARPORT_EPP_FAST make sense for this function?)

SEE ALSO

epp_write_data, epp_read_data, epp_write_addr

port->ops->ecp_write_data - write a block of ECP data
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*ecp_write_data) (struct parport *port,
				  const void *buf, size_t len, int flags);
	...
};

DESCRIPTION

Writes a block of ECP data.  The 'flags' parameter is ignored.

RETURN VALUE

The number of bytes written.

SEE ALSO

ecp_read_data, ecp_write_addr

port->ops->ecp_read_data - read a block of ECP data
------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*ecp_read_data) (struct parport *port,
				 void *buf, size_t len, int flags);
	...
};

DESCRIPTION

Reads a block of ECP data.  The 'flags' parameter is ignored.

RETURN VALUE

The number of bytes read.  NB. There may be more unread data in a
FIFO.  Is there a way of stunning the FIFO to prevent this?

SEE ALSO

ecp_write_block, ecp_write_addr

port->ops->ecp_write_addr - write a block of ECP addresses
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*ecp_write_addr) (struct parport *port,
				  const void *buf, size_t len, int flags);
	...
};

DESCRIPTION

Writes a block of ECP addresses.  The 'flags' parameter is ignored.

RETURN VALUE

The number of bytes written.

NOTES

This may use a FIFO, and if so shall not return until the FIFO is empty.

SEE ALSO

ecp_read_data, ecp_write_data

port->ops->nibble_read_data - read a block of data in nibble mode
---------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*nibble_read_data) (struct parport *port,
				    void *buf, size_t len, int flags);
	...
};

DESCRIPTION

Reads a block of data in nibble mode.  The 'flags' parameter is ignored.

RETURN VALUE

The number of whole bytes read.

SEE ALSO

byte_read_data, compat_write_data

port->ops->byte_read_data - read a block of data in byte mode
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*byte_read_data) (struct parport *port,
				  void *buf, size_t len, int flags);
	...
};

DESCRIPTION

Reads a block of data in byte mode.  The 'flags' parameter is ignored.

RETURN VALUE

The number of bytes read.

SEE ALSO

nibble_read_data, compat_write_data

port->ops->compat_write_data - write a block of data in compatibility mode
----------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
	...
	size_t (*compat_write_data) (struct parport *port,
				     const void *buf, size_t len, int flags);
	...
};

DESCRIPTION

Writes a block of data in compatibility mode.  The 'flags' parameter
is ignored.

RETURN VALUE

The number of bytes written.

SEE ALSO

nibble_read_data, byte_read_data

Privacy Policy