summaryrefslogtreecommitdiff
path: root/drivers/parport/share.c
blob: 49c74ded8a53ce70279246c9d85aa4698c084110 (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
/*
 * Parallel-port resource manager code.
 *
 * Authors: David Campbell <campbell@tirian.che.curtin.edu.au>
 *          Tim Waugh <tim@cyberelk.demon.co.uk>
 *          Jose Renau <renau@acm.org>
 *          Philip Blundell <philb@gnu.org>
 *	    Andrea Arcangeli
 *
 * based on work by Grant Guenther <grant@torque.net>
 *          and Philip Blundell
 *
 * Any part of this program may be used in documents licensed under
 * the GNU Free Documentation License, Version 1.1 or any later version
 * published by the Free Software Foundation.
 */

#undef PARPORT_DEBUG_SHARING		/* undef for production */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/threads.h>
#include <linux/parport.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/kmod.h>
#include <linux/device.h>

#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <asm/irq.h>

#undef PARPORT_PARANOID

#define PARPORT_DEFAULT_TIMESLICE	(HZ/5)

unsigned long parport_default_timeslice = PARPORT_DEFAULT_TIMESLICE;
int parport_default_spintime =  DEFAULT_SPIN_TIME;

static LIST_HEAD(portlist);
static DEFINE_SPINLOCK(parportlist_lock);

/* list of all allocated ports, sorted by ->number */
static LIST_HEAD(all_ports);
static DEFINE_SPINLOCK(full_list_lock);

static LIST_HEAD(drivers);

static DEFINE_MUTEX(registration_lock);

/* What you can do to a port that's gone away.. */
static void dead_write_lines(struct parport *p, unsigned char b){}
static unsigned char dead_read_lines(struct parport *p) { return 0; }
static unsigned char dead_frob_lines(struct parport *p, unsigned char b,
			     unsigned char c) { return 0; }
static void dead_onearg(struct parport *p){}
static void dead_initstate(struct pardevice *d, struct parport_state *s) { }
static void dead_state(struct parport *p, struct parport_state *s) { }
static size_t dead_write(struct parport *p, const void *b, size_t l, int f)
{ return 0; }
static size_t dead_read(struct parport *p, void *b, size_t l, int f)
{ return 0; }
static struct parport_operations dead_ops = {
	.write_data	= dead_write_lines,	/* data */
	.read_data	= dead_read_lines,

	.write_control	= dead_write_lines,	/* control */
	.read_control	= dead_read_lines,
	.frob_control	= dead_frob_lines,

	.read_status	= dead_read_lines,	/* status */

	.enable_irq	= dead_onearg,		/* enable_irq */
	.disable_irq	= dead_onearg,		/* disable_irq */

	.data_forward	= dead_onearg,		/* data_forward */
	.data_reverse	= dead_onearg,		/* data_reverse */

	.init_state	= dead_initstate,	/* init_state */
	.save_state	= dead_state,
	.restore_state	= dead_state,

	.epp_write_data	= dead_write,		/* epp */
	.epp_read_data	= dead_read,
	.epp_write_addr	= dead_write,
	.epp_read_addr	= dead_read,

	.ecp_write_data	= dead_write,		/* ecp */
	.ecp_read_data	= dead_read,
	.ecp_write_addr	= dead_write,

	.compat_write_data	= dead_write,	/* compat */
	.nibble_read_data	= dead_read,	/* nibble */
	.byte_read_data		= dead_read,	/* byte */

	.owner		= NULL,
};

static struct device_type parport_device_type = {
	.name = "parport",
};

static int is_parport(struct device *dev)
{
	return dev->type == &parport_device_type;
}

static int parport_probe(struct device *dev)
{
	struct parport_driver *drv;

	if (is_parport(dev))
		return -ENODEV;

	drv = to_parport_driver(dev->driver);
	if (!drv->probe) {
		/* if driver has not defined a custom probe */
		struct pardevice *par_dev = to_pardevice(dev);

		if (strcmp(par_dev->name, drv->name))
			return -ENODEV;
		return 0;
	}
	/* if driver defined its own probe */
	return drv->probe(to_pardevice(dev));
}

static struct bus_type parport_bus_type = {
	.name = "parport",
	.probe = parport_probe,
};

int parport_bus_init(void)
{
	return bus_register(&parport_bus_type);
}

void parport_bus_exit(void)
{
	bus_unregister(&parport_bus_type);
}

/*
 * iterates through all the drivers registered with the bus and sends the port
 * details to the match_port callback of the driver, so that the driver can
 * know about the new port that just registered with the bus and decide if it
 * wants to use this new port.
 */
static int driver_check(struct device_driver *dev_drv, void *_port)
{
	struct parport *port = _port;
	struct parport_driver *drv = to_parport_driver(dev_drv);

	if (drv->match_port)
		drv->match_port(port);
	return 0;
}

/* Call attach(port) for each registered driver. */
static void attach_driver_chain(struct parport *port)
{
	/* caller has exclusive registration_lock */
	struct parport_driver *drv;

	list_for_each_entry(drv, &drivers, list)
		drv->attach(port);

	/*
	 * call the driver_check function of the drivers registered in
	 * new device model
	 */

	bus_for_each_drv(&parport_bus_type, NULL, port, driver_check);
}

static int driver_detach(struct device_driver *_drv, void *_port)
{
	struct parport *port = _port;
	struct parport_driver *drv = to_parport_driver(_drv);

	if (drv->detach)
		drv->detach(port);
	return 0;
}

/* Call detach(port) for each registered driver. */
static void detach_driver_chain(struct parport *port)
{
	struct parport_driver *drv;
	/* caller has exclusive registration_lock */
	list_for_each_entry(drv, &drivers, list)
		drv->detach(port);

	/*
	 * call the detach function of the drivers registered in
	 * new device model
	 */

	bus_for_each_drv(&parport_bus_type, NULL, port, driver_detach);
}

/* Ask kmod for some lowlevel drivers. */
static void get_lowlevel_driver(void)
{
	/*
	 * There is no actual module called this: you should set
	 * up an alias for modutils.
	 */
	request_module("parport_lowlevel");
}

/*
 * iterates through all the devices connected to the bus and sends the device
 * details to the match_port callback of the driver, so that the driver can
 * know what are all the ports that are connected to the bus and choose the
 * port to which it wants to register its device.
 */
static int port_check(struct device *dev, void *dev_drv)
{
	struct parport_driver *drv = dev_drv;

	/* only send ports, do not send other devices connected to bus */
	if (is_parport(dev))
		drv->match_port(to_parport_dev(dev));
	return 0;
}

/*
 * Iterates through all the devices connected to the bus and return 1
 * if the device is a parallel port.
 */

static int port_detect(struct device *dev, void *dev_drv)
{
	if (is_parport(dev))
		return 1;
	return 0;
}

/**
 *	__parport_register_driver - register a parallel port device driver
 *	@drv: structure describing the driver
 *	@owner: owner module of drv
 *	@mod_name: module name string
 *
 *	This can be called by a parallel port device driver in order
 *	to receive notifications about ports being found in the
 *	system, as well as ports no longer available.
 *
 *	If devmodel is true then the new device model is used
 *	for registration.
 *
 *	The @drv structure is allocated by the caller and must not be
 *	deallocated until after calling parport_unregister_driver().
 *
 *	If using the non device model:
 *	The driver's attach() function may block.  The port that
 *	attach() is given will be valid for the duration of the
 *	callback, but if the driver wants to take a copy of the
 *	pointer it must call parport_get_port() to do so.  Calling
 *	parport_register_device() on that port will do this for you.
 *
 *	The driver's detach() function may block.  The port that
 *	detach() is given will be valid for the duration of the
 *	callback, but if the driver wants to take a copy of the
 *	pointer it must call parport_get_port() to do so.
 *
 *
 *	Returns 0 on success. The non device model will always succeeds.
 *	but the new device model can fail and will return the error code.
 **/

int __parport_register_driver(struct parport_driver *drv, struct module *owner,
			      const char *mod_name)
{
	/* using device model */
	int ret;

	/* initialize common driver fields */
	drv->driver.name = drv->name;
	drv->driver.bus = &parport_bus_type;
	drv->driver.owner = owner;
	drv->driver.mod_name = mod_name;
	ret = driver_register(&drv->driver);
	if (ret)
		return ret;

	/*
	 * check if bus has any parallel port registered, if
	 * none is found then load the lowlevel driver.
	 */
	ret = bus_for_each_dev(&parport_bus_type, NULL, NULL,
			       port_detect);
	if (!ret)
		get_lowlevel_driver();

	mutex_lock(&registration_lock);
	if (drv->match_port)
		bus_for_each_dev(&parport_bus_type, NULL, drv,
				 port_check);
	mutex_unlock(&registration_lock);

	return 0;
}
EXPORT_SYMBOL(__parport_register_driver);

static int port_detach(struct device *dev, void *_drv)
{
	struct parport_driver *drv = _drv;

	if (is_parport(dev) && drv->detach)
		drv->detach(to_parport_dev(dev));

	return 0;
}

/**
 *	parport_unregister_driver - deregister a parallel port device driver
 *	@drv: structure describing the driver that was given to
 *	      parport_register_driver()
 *
 *	This should be called by a parallel port device driver that
 *	has registered itself using parport_register_driver() when it
 *	is about to be unloaded.
 *
 *	When it returns, the driver's attach() routine will no longer
 *	be called, and for each port that attach() was called for, the
 *	detach() routine will have been called.
 *
 *	All the driver's attach() and detach() calls are guaranteed to have
 *	finished by the time this function returns.
 **/

void parport_unregister_driver(struct parport_driver *drv)
{
	mutex_lock(&registration_lock);
	bus_for_each_dev(&parport_bus_type, NULL, drv, port_detach);
	driver_unregister(&drv->driver);
	mutex_unlock(&registration_lock);
}
EXPORT_SYMBOL(parport_unregister_driver);

static void free_port(struct device *dev)
{
	int d;
	struct parport *port = to_parport_dev(dev);

	spin_lock(&full_list_lock);
	list_del(&port->full_list);
	spin_unlock(&full_list_lock);
	for (d = 0; d < 5; d++) {
		kfree(port->probe_info[d].class_name);
		kfree(port->probe_info[d].mfr);
		kfree(port->probe_info[d].model);
		kfree(port->probe_info[d].cmdset);
		kfree(port->probe_info[d].description);
	}

	kfree(port);
}

/**
 *	parport_get_port - increment a port's reference count
 *	@port: the port
 *
 *	This ensures that a struct parport pointer remains valid
 *	until the matching parport_put_port() call.
 **/

struct parport *parport_get_port(struct parport *port)
{
	struct device *dev = get_device(&port->bus_dev);

	return to_parport_dev(dev);
}
EXPORT_SYMBOL(parport_get_port);

void parport_del_port(struct parport *port)
{
	device_unregister(&port->bus_dev);
}
EXPORT_SYMBOL(parport_del_port);

/**
 *	parport_put_port - decrement a port's reference count
 *	@port: the port
 *
 *	This should be called once for each call to parport_get_port(),
 *	once the port is no longer needed. When the reference count reaches
 *	zero (port is no longer used), free_port is called.
 **/

void parport_put_port(struct parport *port)
{
	put_device(&port->bus_dev);
}
EXPORT_SYMBOL(parport_put_port);

/**
 *	parport_register_port - register a parallel port
 *	@base: base I/O address
 *	@irq: IRQ line
 *	@dma: DMA channel
 *	@ops: pointer to the port driver's port operations structure
 *
 *	When a parallel port (lowlevel) driver finds a port that
 *	should be made available to parallel port device drivers, it
 *	should call parport_register_port().  The @base, @irq, and
 *	@dma parameters are for the convenience of port drivers, and
 *	for ports where they aren't meaningful needn't be set to
 *	anything special.  They can be altered afterwards by adjusting
 *	the relevant members of the parport structure that is returned
 *	and represents the port.  They should not be tampered with
 *	after calling parport_announce_port, however.
 *
 *	If there are parallel port device drivers in the system that
 *	have registered themselves using parport_register_driver(),
 *	they are not told about the port at this time; that is done by
 *	parport_announce_port().
 *
 *	The @ops structure is allocated by the caller, and must not be
 *	deallocated before calling parport_remove_port().
 *
 *	If there is no memory to allocate a new parport structure,
 *	this function will return %NULL.
 **/

struct parport *parport_register_port(unsigned long base, int irq, int dma,
				      struct parport_operations *ops)
{
	struct list_head *l;
	struct parport *tmp;
	int num;
	int device;
	int ret;

	tmp = kzalloc(sizeof(struct parport), GFP_KERNEL);
	if (!tmp)
		return NULL;

	/* Init our structure */
	tmp->base = base;
	tmp->irq = irq;
	tmp->dma = dma;
	tmp->muxport = tmp->daisy = tmp->muxsel = -1;
	INIT_LIST_HEAD(&tmp->list);
	tmp->ops = ops;
	tmp->physport = tmp;
	rwlock_init(&tmp->cad_lock);
	spin_lock_init(&tmp->waitlist_lock);
	spin_lock_init(&tmp->pardevice_lock);
	tmp->ieee1284.mode = IEEE1284_MODE_COMPAT;
	tmp->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
	sema_init(&tmp->ieee1284.irq, 0);
	tmp->spintime = parport_default_spintime;
	atomic_set(&tmp->ref_count, 1);

	/* Search for the lowest free parport number. */

	spin_lock(&full_list_lock);
	num = 0;
	list_for_each(l, &all_ports) {
		struct parport *p = list_entry(l, struct parport, full_list);

		if (p->number != num++)
			break;
	}
	tmp->portnum = tmp->number = num;
	list_add_tail(&tmp->full_list, l);
	spin_unlock(&full_list_lock);

	/*
	 * Now that the portnum is known finish doing the Init.
	 */
	dev_set_name(&tmp->bus_dev, "parport%d", tmp->portnum);
	tmp->bus_dev.bus = &parport_bus_type;
	tmp->bus_dev.release = free_port;
	tmp->bus_dev.type = &parport_device_type;

	tmp->name = dev_name(&tmp->bus_dev);

	for (device = 0; device < 5; device++)
		/* assume the worst */
		tmp->probe_info[device].class = PARPORT_CLASS_LEGACY;

	ret = device_register(&tmp->bus_dev);
	if (ret) {
		put_device(&tmp->bus_dev);
		return NULL;
	}

	return tmp;
}
EXPORT_SYMBOL(parport_register_port);

/**
 *	parport_announce_port - tell device drivers about a parallel port
 *	@port: parallel port to announce
 *
 *	After a port driver has registered a parallel port with
 *	parport_register_port, and performed any necessary
 *	initialisation or adjustments, it should call
 *	parport_announce_port() in order to notify all device drivers
 *	that have called parport_register_driver().  Their attach()
 *	functions will be called, with @port as the parameter.
 **/

void parport_announce_port(struct parport *port)
{
	int i;

#ifdef CONFIG_PARPORT_1284
	/* Analyse the IEEE1284.3 topology of the port. */
	parport_daisy_init(port);
#endif

	if (!port->dev)
		pr_warn("%s: fix this legacy no-device port driver!\n",
			port->name);

	parport_proc_register(port);
	mutex_lock(&registration_lock);
	spin_lock_irq(&parportlist_lock);
	list_add_tail(&port->list, &portlist);
	for (i = 1; i < 3; i++) {
		struct parport *slave = port->slaves[i-1];
		if (slave)
			list_add_tail(&slave->list, &portlist);
	}
	spin_unlock_irq(&parportlist_lock);

	/* Let drivers know that new port(s) has arrived. */
	attach_driver_chain(port);
	for (i = 1; i < 3; i++) {
		struct parport *slave = port->slaves[i-1];
		if (slave)
			attach_driver_chain(slave);
	}
	mutex_unlock(&registration_lock);
}
EXPORT_SYMBOL(parport_announce_port);

/**
 *	parport_remove_port - deregister a parallel port
 *	@port: parallel port to deregister
 *
 *	When a parallel port driver is forcibly unloaded, or a
 *	parallel port becomes inaccessible, the port driver must call
 *	this function in order to deal with device drivers that still
 *	want to use it.
 *
 *	The parport structure associated with the port has its
 *	operations structure replaced with one containing 'null'
 *	operations that return errors or just don't do anything.
 *
 *	Any drivers that have registered themselves using
 *	parport_register_driver() are notified that the port is no
 *	longer accessible by having their detach() routines called
 *	with @port as the parameter.
 **/

void parport_remove_port(struct parport *port)
{
	int i;

	mutex_lock(&registration_lock);

	/* Spread the word. */
	detach_driver_chain(port);

#ifdef CONFIG_PARPORT_1284
	/* Forget the IEEE1284.3 topology of the port. */
	parport_daisy_fini(port);
	for (i = 1; i < 3; i++) {
		struct parport *slave = port->slaves[i-1];
		if (!slave)
			continue;
		detach_driver_chain(slave);
		parport_daisy_fini(slave);
	}
#endif

	port->ops = &dead_ops;
	spin_lock(&parportlist_lock);
	list_del_init(&port->list);
	for (i = 1; i < 3; i++) {
		struct parport *slave = port->slaves[i-1];
		if (slave)
			list_del_init(&slave->list);
	}
	spin_unlock(&parportlist_lock);

	mutex_unlock(&registration_lock);

	parport_proc_unregister(port);

	for (i = 1; i < 3; i++) {
		struct parport *slave = port->slaves[i-1];
		if (slave)
			parport_put_port(slave);
	}
}
EXPORT_SYMBOL(parport_remove_port);

static void free_pardevice(struct device *dev)
{
	struct pardevice *par_dev = to_pardevice(dev);

	kfree_const(par_dev->name);
	kfree(par_dev);
}

/**
 *	parport_register_dev_model - register a device on a parallel port
 *	@port: port to which the device is attached
 *	@name: a name to refer to the device
 *	@par_dev_cb: struct containing callbacks
 *	@id: device number to be given to the device
 *
 *	This function, called by parallel port device drivers,
 *	declares that a device is connected to a port, and tells the
 *	system all it needs to know.
 *
 *	The struct pardev_cb contains pointer to callbacks. preemption
 *	callback function, @preempt, is called when this device driver
 *	has claimed access to the port but another device driver wants
 *	to use it.  It is given, @private, as its parameter, and should
 *	return zero if it is willing for the system to release the port
 *	to another driver on its behalf. If it wants to keep control of
 *	the port it should return non-zero, and no action will be taken.
 *	It is good manners for the driver to try to release the port at
 *	the earliest opportunity after its preemption callback rejects a
 *	preemption attempt. Note that if a preemption callback is happy
 *	for preemption to go ahead, there is no need to release the
 *	port; it is done automatically. This function may not block, as
 *	it may be called from interrupt context. If the device driver
 *	does not support preemption, @preempt can be %NULL.
 *
 *	The wake-up ("kick") callback function, @wakeup, is called when
 *	the port is available to be claimed for exclusive access; that
 *	is, parport_claim() is guaranteed to succeed when called from
 *	inside the wake-up callback function.  If the driver wants to
 *	claim the port it should do so; otherwise, it need not take
 *	any action.  This function may not block, as it may be called
 *	from interrupt context.  If the device driver does not want to
 *	be explicitly invited to claim the port in this way, @wakeup can
 *	be %NULL.
 *
 *	The interrupt handler, @irq_func, is called when an interrupt
 *	arrives from the parallel port.  Note that if a device driver
 *	wants to use interrupts it should use parport_enable_irq(),
 *	and can also check the irq member of the parport structure
 *	representing the port.
 *
 *	The parallel port (lowlevel) driver is the one that has called
 *	request_irq() and whose interrupt handler is called first.
 *	This handler does whatever needs to be done to the hardware to
 *	acknowledge the interrupt (for PC-style ports there is nothing
 *	special to be done).  It then tells the IEEE 1284 code about
 *	the interrupt, which may involve reacting to an IEEE 1284
 *	event depending on the current IEEE 1284 phase.  After this,
 *	it calls @irq_func.  Needless to say, @irq_func will be called
 *	from interrupt context, and may not block.
 *
 *	The %PARPORT_DEV_EXCL flag is for preventing port sharing, and
 *	so should only be used when sharing the port with other device
 *	drivers is impossible and would lead to incorrect behaviour.
 *	Use it sparingly!  Normally, @flags will be zero.
 *
 *	This function returns a pointer to a structure that represents
 *	the device on the port, or %NULL if there is not enough memory
 *	to allocate space for that structure.
 **/

struct pardevice *
parport_register_dev_model(struct parport *port, const char *name,
			   const struct pardev_cb *par_dev_cb, int id)
{
	struct pardevice *par_dev;
	const char *devname;
	int ret;

	if (port->physport->flags & PARPORT_FLAG_EXCL) {
		/* An exclusive device is registered. */
		pr_err("%s: no more devices allowed\n", port->name);
		return NULL;
	}

	if (par_dev_cb->flags & PARPORT_DEV_LURK) {
		if (!par_dev_cb->preempt || !par_dev_cb->wakeup) {
			pr_info("%s: refused to register lurking device (%s) without callbacks\n",
				port->name, name);
			return NULL;
		}
	}

	if (par_dev_cb->flags & PARPORT_DEV_EXCL) {
		if (port->physport->devices) {
			/*
			 * If a device is already registered and this new
			 * device wants exclusive access, then no need to
			 * continue as we can not grant exclusive access to
			 * this device.
			 */
			pr_err("%s: cannot grant exclusive access for device %s\n",
			       port->name, name);
			return NULL;
		}
	}

	if (!try_module_get(port->ops->owner))
		return NULL;

	parport_get_port(port);

	par_dev = kzalloc(sizeof(*par_dev), GFP_KERNEL);
	if (!par_dev)
		goto err_put_port;

	par_dev->state = kzalloc(sizeof(*par_dev->state), GFP_KERNEL);
	if (!par_dev->state)
		goto err_put_par_dev;

	devname = kstrdup_const(name, GFP_KERNEL);
	if (!devname)
		goto err_free_par_dev;

	par_dev->name = devname;
	par_dev->port = port;
	par_dev->daisy = -1;
	par_dev->preempt = par_dev_cb->preempt;
	par_dev->wakeup = par_dev_cb->wakeup;
	par_dev->private = par_dev_cb->private;
	par_dev->flags = par_dev_cb->flags;
	par_dev->irq_func = par_dev_cb->irq_func;
	par_dev->waiting = 0;
	par_dev->timeout = 5 * HZ;

	par_dev->dev.parent = &port->bus_dev;
	par_dev->dev.bus = &parport_bus_type;
	ret = dev_set_name(&par_dev->dev, "%s.%d", devname, id);
	if (ret)
		goto err_free_devname;
	par_dev->dev.release = free_pardevice;
	par_dev->devmodel = true;
	ret = device_register(&par_dev->dev);
	if (ret) {
		kfree(par_dev->state);
		put_device(&par_dev->dev);
		goto err_put_port;
	}

	/* Chain this onto the list */
	par_dev->prev = NULL;
	/*
	 * This function must not run from an irq handler so we don' t need
	 * to clear irq on the local CPU. -arca
	 */
	spin_lock(&port->physport->pardevice_lock);

	if (par_dev_cb->flags & PARPORT_DEV_EXCL) {
		if (port->physport->devices) {
			spin_unlock(&port->physport->pardevice_lock);
			pr_debug("%s: cannot grant exclusive access for device %s\n",
				 port->name, name);
			kfree(par_dev->state);
			device_unregister(&par_dev->dev);
			goto err_put_port;
		}
		port->flags |= PARPORT_FLAG_EXCL;
	}

	par_dev->next = port->physport->devices;
	wmb();	/*
		 * Make sure that tmp->next is written before it's
		 * added to the list; see comments marked 'no locking
		 * required'
		 */
	if (port->physport->devices)
		port->physport->devices->prev = par_dev;
	port->physport->devices = par_dev;
	spin_unlock(&port->physport->pardevice_lock);

	init_waitqueue_head(&par_dev->wait_q);
	par_dev->timeslice = parport_default_timeslice;
	par_dev->waitnext = NULL;
	par_dev->waitprev = NULL;

	/*
	 * This has to be run as last thing since init_state may need other
	 * pardevice fields. -arca
	 */
	port->ops->init_state(par_dev, par_dev->state);
	if (!test_and_set_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags)) {
		port->proc_device = par_dev;
		parport_device_proc_register(par_dev);
	}

	return par_dev;

err_free_devname:
	kfree_const(devname);
err_free_par_dev:
	kfree(par_dev->state);
err_put_par_dev:
	if (!par_dev->devmodel)
		kfree(par_dev);
err_put_port:
	parport_put_port(port);
	module_put(port->ops->owner);

	return NULL;
}
EXPORT_SYMBOL(parport_register_dev_model);

/**
 *	parport_unregister_device - deregister a device on a parallel port
 *	@dev: pointer to structure representing device
 *
 *	This undoes the effect of parport_register_device().
 **/

void parport_unregister_device(struct pardevice *dev)
{
	struct parport *port;

#ifdef PARPORT_PARANOID
	if (!dev) {
		pr_err("%s: passed NULL\n", __func__);
		return;
	}
#endif

	port = dev->port->physport;

	if (port->proc_device == dev) {
		port->proc_device = NULL;
		clear_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags);
		parport_device_proc_unregister(dev);
	}

	if (port->cad == dev) {
		printk(KERN_DEBUG "%s: %s forgot to release port\n",
		       port->name, dev->name);
		parport_release(dev);
	}

	spin_lock(&port->pardevice_lock);
	if (dev->next)
		dev->next->prev = dev->prev;
	if (dev->prev)
		dev->prev->next = dev->next;
	else
		port->devices = dev->next;

	if (dev->flags & PARPORT_DEV_EXCL)
		port->flags &= ~PARPORT_FLAG_EXCL;

	spin_unlock(&port->pardevice_lock);

	/*
	 * Make sure we haven't left any pointers around in the wait
	 * list.
	 */
	spin_lock_irq(&port->waitlist_lock);
	if (dev->waitprev || dev->waitnext || port->waithead == dev) {
		if (dev->waitprev)
			dev->waitprev->waitnext = dev->waitnext;
		else
			port->waithead = dev->waitnext;
		if (dev->waitnext)
			dev->waitnext->waitprev = dev->waitprev;
		else
			port->waittail = dev->waitprev;
	}
	spin_unlock_irq(&port->waitlist_lock);

	kfree(dev->state);
	device_unregister(&dev->dev);

	module_put(port->ops->owner);
	parport_put_port(port);
}
EXPORT_SYMBOL(parport_unregister_device);

/**
 *	parport_find_number - find a parallel port by number
 *	@number: parallel port number
 *
 *	This returns the parallel port with the specified number, or
 *	%NULL if there is none.
 *
 *	There is an implicit parport_get_port() done already; to throw
 *	away the reference to the port that parport_find_number()
 *	gives you, use parport_put_port().
 */

struct parport *parport_find_number(int number)
{
	struct parport *port, *result = NULL;

	if (list_empty(&portlist))
		get_lowlevel_driver();

	spin_lock(&parportlist_lock);
	list_for_each_entry(port, &portlist, list) {
		if (port->number == number) {
			result = parport_get_port(port);
			break;
		}
	}
	spin_unlock(&parportlist_lock);
	return result;
}
EXPORT_SYMBOL(parport_find_number);

/**
 *	parport_find_base - find a parallel port by base address
 *	@base: base I/O address
 *
 *	This returns the parallel port with the specified base
 *	address, or %NULL if there is none.
 *
 *	There is an implicit parport_get_port() done already; to throw
 *	away the reference to the port that parport_find_base()
 *	gives you, use parport_put_port().
 */

struct parport *parport_find_base(unsigned long base)
{
	struct parport *port, *result = NULL;

	if (list_empty(&portlist))
		get_lowlevel_driver();

	spin_lock(&parportlist_lock);
	list_for_each_entry(port, &portlist, list) {
		if (port->base == base) {
			result = parport_get_port(port);
			break;
		}
	}
	spin_unlock(&parportlist_lock);
	return result;
}
EXPORT_SYMBOL(parport_find_base);

/**
 *	parport_claim - claim access to a parallel port device
 *	@dev: pointer to structure representing a device on the port
 *
 *	This function will not block and so can be used from interrupt
 *	context.  If parport_claim() succeeds in claiming access to
 *	the port it returns zero and the port is available to use.  It
 *	may fail (returning non-zero) if the port is in use by another
 *	driver and that driver is not willing to relinquish control of
 *	the port.
 **/

int parport_claim(struct pardevice *dev)
{
	struct pardevice *oldcad;
	struct parport *port = dev->port->physport;
	unsigned long flags;

	if (port->cad == dev) {
		pr_info("%s: %s already owner\n", dev->port->name, dev->name);
		return 0;
	}

	/* Preempt any current device */
	write_lock_irqsave(&port->cad_lock, flags);
	oldcad = port->cad;
	if (oldcad) {
		if (oldcad->preempt) {
			if (oldcad->preempt(oldcad->private))
				goto blocked;
			port->ops->save_state(port, dev->state);
		} else
			goto blocked;

		if (port->cad != oldcad) {
			/*
			 * I think we'll actually deadlock rather than
			 * get here, but just in case..
			 */
			pr_warn("%s: %s released port when preempted!\n",
				port->name, oldcad->name);
			if (port->cad)
				goto blocked;
		}
	}

	/* Can't fail from now on, so mark ourselves as no longer waiting.  */
	if (dev->waiting & 1) {
		dev->waiting = 0;

		/* Take ourselves out of the wait list again.  */
		spin_lock_irq(&port->waitlist_lock);
		if (dev->waitprev)
			dev->waitprev->waitnext = dev->waitnext;
		else
			port->waithead = dev->waitnext;
		if (dev->waitnext)
			dev->waitnext->waitprev = dev->waitprev;
		else
			port->waittail = dev->waitprev;
		spin_unlock_irq(&port->waitlist_lock);
		dev->waitprev = dev->waitnext = NULL;
	}

	/* Now we do the change of devices */
	port->cad = dev;

#ifdef CONFIG_PARPORT_1284
	/* If it's a mux port, select it. */
	if (dev->port->muxport >= 0) {
		/* FIXME */
		port->muxsel = dev->port->muxport;
	}

	/* If it's a daisy chain device, select it. */
	if (dev->daisy >= 0) {
		/* This could be lazier. */
		if (!parport_daisy_select(port, dev->daisy,
					   IEEE1284_MODE_COMPAT))
			port->daisy = dev->daisy;
	}
#endif /* IEEE1284.3 support */

	/* Restore control registers */
	port->ops->restore_state(port, dev->state);
	write_unlock_irqrestore(&port->cad_lock, flags);
	dev->time = jiffies;
	return 0;

blocked:
	/*
	 * If this is the first time we tried to claim the port, register an
	 * interest.  This is only allowed for devices sleeping in
	 * parport_claim_or_block(), or those with a wakeup function.
	 */

	/* The cad_lock is still held for writing here */
	if (dev->waiting & 2 || dev->wakeup) {
		spin_lock(&port->waitlist_lock);
		if (test_and_set_bit(0, &dev->waiting) == 0) {
			/* First add ourselves to the end of the wait list. */
			dev->waitnext = NULL;
			dev->waitprev = port->waittail;
			if (port->waittail) {
				port->waittail->waitnext = dev;
				port->waittail = dev;
			} else
				port->waithead = port->waittail = dev;
		}
		spin_unlock(&port->waitlist_lock);
	}
	write_unlock_irqrestore(&port->cad_lock, flags);
	return -EAGAIN;
}
EXPORT_SYMBOL(parport_claim);

/**
 *	parport_claim_or_block - claim access to a parallel port device
 *	@dev: pointer to structure representing a device on the port
 *
 *	This behaves like parport_claim(), but will block if necessary
 *	to wait for the port to be free.  A return value of 1
 *	indicates that it slept; 0 means that it succeeded without
 *	needing to sleep.  A negative error code indicates failure.
 **/

int parport_claim_or_block(struct pardevice *dev)
{
	int r;

	/*
	 * Signal to parport_claim() that we can wait even without a
	 * wakeup function.
	 */
	dev->waiting = 2;

	/* Try to claim the port.  If this fails, we need to sleep.  */
	r = parport_claim(dev);
	if (r == -EAGAIN) {
#ifdef PARPORT_DEBUG_SHARING
		printk(KERN_DEBUG "%s: parport_claim() returned -EAGAIN\n",
		       dev->name);
#endif
		/*
		 * FIXME!!! Use the proper locking for dev->waiting,
		 * and make this use the "wait_event_interruptible()"
		 * interfaces. The cli/sti that used to be here
		 * did nothing.
		 *
		 * See also parport_release()
		 */

		/*
		 * If dev->waiting is clear now, an interrupt
		 * gave us the port and we would deadlock if we slept.
		 */
		if (dev->waiting) {
			wait_event_interruptible(dev->wait_q,
						 !dev->waiting);
			if (signal_pending(current))
				return -EINTR;
			r = 1;
		} else {
			r = 0;
#ifdef PARPORT_DEBUG_SHARING
			printk(KERN_DEBUG "%s: didn't sleep in parport_claim_or_block()\n",
			       dev->name);
#endif
		}

#ifdef PARPORT_DEBUG_SHARING
		if (dev->port->physport->cad != dev)
			printk(KERN_DEBUG "%s: exiting parport_claim_or_block but %s owns port!\n",
			       dev->name, dev->port->physport->cad ?
			       dev->port->physport->cad->name : "nobody");
#endif
	}
	dev->waiting = 0;
	return r;
}
EXPORT_SYMBOL(parport_claim_or_block);

/**
 *	parport_release - give up access to a parallel port device
 *	@dev: pointer to structure representing parallel port device
 *
 *	This function cannot fail, but it should not be called without
 *	the port claimed.  Similarly, if the port is already claimed
 *	you should not try claiming it again.
 **/

void parport_release(struct pardevice *dev)
{
	struct parport *port = dev->port->physport;
	struct pardevice *pd;
	unsigned long flags;

	/* Make sure that dev is the current device */
	write_lock_irqsave(&port->cad_lock, flags);
	if (port->cad != dev) {
		write_unlock_irqrestore(&port->cad_lock, flags);
		pr_warn("%s: %s tried to release parport when not owner\n",
			port->name, dev->name);
		return;
	}

#ifdef CONFIG_PARPORT_1284
	/* If this is on a mux port, deselect it. */
	if (dev->port->muxport >= 0) {
		/* FIXME */
		port->muxsel = -1;
	}

	/* If this is a daisy device, deselect it. */
	if (dev->daisy >= 0) {
		parport_daisy_deselect_all(port);
		port->daisy = -1;
	}
#endif

	port->cad = NULL;
	write_unlock_irqrestore(&port->cad_lock, flags);

	/* Save control registers */
	port->ops->save_state(port, dev->state);

	/*
	 * If anybody is waiting, find out who's been there longest and
	 * then wake them up. (Note: no locking required)
	 */
	/* !!! LOCKING IS NEEDED HERE */
	for (pd = port->waithead; pd; pd = pd->waitnext) {
		if (pd->waiting & 2) { /* sleeping in claim_or_block */
			parport_claim(pd);
			if (waitqueue_active(&pd->wait_q))
				wake_up_interruptible(&pd->wait_q);
			return;
		} else if (pd->wakeup) {
			pd->wakeup(pd->private);
			if (dev->port->cad) /* racy but no matter */
				return;
		} else {
			pr_err("%s: don't know how to wake %s\n",
			       port->name, pd->name);
		}
	}

	/*
	 * Nobody was waiting, so walk the list to see if anyone is
	 * interested in being woken up. (Note: no locking required)
	 */
	/* !!! LOCKING IS NEEDED HERE */
	for (pd = port->devices; !port->cad && pd; pd = pd->next) {
		if (pd->wakeup && pd != dev)
			pd->wakeup(pd->private);
	}
}
EXPORT_SYMBOL(parport_release);

irqreturn_t parport_irq_handler(int irq, void *dev_id)
{
	struct parport *port = dev_id;

	parport_generic_irq(port);

	return IRQ_HANDLED;
}
EXPORT_SYMBOL(parport_irq_handler);

MODULE_LICENSE("GPL");