summaryrefslogtreecommitdiff
path: root/drivers/staging/comedi/drivers.c
blob: a5bf2cc165c01e6c9a452ed56e6b02a5e901b4fe (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
/*
 *  module/drivers.c
 *  functions for manipulating drivers
 *
 *  COMEDI - Linux Control and Measurement Device Interface
 *  Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>
 *  Copyright (C) 2002 Frank Mori Hess <fmhess@users.sourceforge.net>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/dma-direction.h>
#include <linux/interrupt.h>
#include <linux/firmware.h>

#include "comedidev.h"
#include "comedi_internal.h"

struct comedi_driver *comedi_drivers;
/* protects access to comedi_drivers */
DEFINE_MUTEX(comedi_drivers_list_lock);

/**
 * comedi_set_hw_dev() - Set hardware device associated with COMEDI device
 * @dev: COMEDI device.
 * @hw_dev: Hardware device.
 *
 * For automatically configured COMEDI devices (resulting from a call to
 * comedi_auto_config() or one of its wrappers from the low-level COMEDI
 * driver), comedi_set_hw_dev() is called automatically by the COMEDI core
 * to associate the COMEDI device with the hardware device.  It can also be
 * called directly by "legacy" low-level COMEDI drivers that rely on the
 * %COMEDI_DEVCONFIG ioctl to configure the hardware as long as the hardware
 * has a &struct device.
 *
 * If @dev->hw_dev is NULL, it gets a reference to @hw_dev and sets
 * @dev->hw_dev, otherwise, it does nothing.  Calling it multiple times
 * with the same hardware device is not considered an error.  If it gets
 * a reference to the hardware device, it will be automatically 'put' when
 * the device is detached from COMEDI.
 *
 * Returns 0 if @dev->hw_dev was NULL or the same as @hw_dev, otherwise
 * returns -EEXIST.
 */
int comedi_set_hw_dev(struct comedi_device *dev, struct device *hw_dev)
{
	if (hw_dev == dev->hw_dev)
		return 0;
	if (dev->hw_dev)
		return -EEXIST;
	dev->hw_dev = get_device(hw_dev);
	return 0;
}
EXPORT_SYMBOL_GPL(comedi_set_hw_dev);

static void comedi_clear_hw_dev(struct comedi_device *dev)
{
	put_device(dev->hw_dev);
	dev->hw_dev = NULL;
}

/**
 * comedi_alloc_devpriv() - Allocate memory for the device private data
 * @dev: COMEDI device.
 * @size: Size of the memory to allocate.
 *
 * The allocated memory is zero-filled.  @dev->private points to it on
 * return.  The memory will be automatically freed when the COMEDI device is
 * "detached".
 *
 * Returns a pointer to the allocated memory, or NULL on failure.
 */
void *comedi_alloc_devpriv(struct comedi_device *dev, size_t size)
{
	dev->private = kzalloc(size, GFP_KERNEL);
	return dev->private;
}
EXPORT_SYMBOL_GPL(comedi_alloc_devpriv);

/**
 * comedi_alloc_subdevices() - Allocate subdevices for COMEDI device
 * @dev: COMEDI device.
 * @num_subdevices: Number of subdevices to allocate.
 *
 * Allocates and initializes an array of &struct comedi_subdevice for the
 * COMEDI device.  If successful, sets @dev->subdevices to point to the
 * first one and @dev->n_subdevices to the number.
 *
 * Returns 0 on success, -EINVAL if @num_subdevices is < 1, or -ENOMEM if
 * failed to allocate the memory.
 */
int comedi_alloc_subdevices(struct comedi_device *dev, int num_subdevices)
{
	struct comedi_subdevice *s;
	int i;

	if (num_subdevices < 1)
		return -EINVAL;

	s = kcalloc(num_subdevices, sizeof(*s), GFP_KERNEL);
	if (!s)
		return -ENOMEM;
	dev->subdevices = s;
	dev->n_subdevices = num_subdevices;

	for (i = 0; i < num_subdevices; ++i) {
		s = &dev->subdevices[i];
		s->device = dev;
		s->index = i;
		s->async_dma_dir = DMA_NONE;
		spin_lock_init(&s->spin_lock);
		s->minor = -1;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(comedi_alloc_subdevices);

/**
 * comedi_alloc_subdev_readback() - Allocate memory for the subdevice readback
 * @s: COMEDI subdevice.
 *
 * This is called by low-level COMEDI drivers to allocate an array to record
 * the last values written to a subdevice's analog output channels (at least
 * by the %INSN_WRITE instruction), to allow them to be read back by an
 * %INSN_READ instruction.  It also provides a default handler for the
 * %INSN_READ instruction unless one has already been set.
 *
 * On success, @s->readback points to the first element of the array, which
 * is zero-filled.  The low-level driver is responsible for updating its
 * contents.  @s->insn_read will be set to comedi_readback_insn_read()
 * unless it is already non-NULL.
 *
 * Returns 0 on success, -EINVAL if the subdevice has no channels, or
 * -ENOMEM on allocation failure.
 */
int comedi_alloc_subdev_readback(struct comedi_subdevice *s)
{
	if (!s->n_chan)
		return -EINVAL;

	s->readback = kcalloc(s->n_chan, sizeof(*s->readback), GFP_KERNEL);
	if (!s->readback)
		return -ENOMEM;

	if (!s->insn_read)
		s->insn_read = comedi_readback_insn_read;

	return 0;
}
EXPORT_SYMBOL_GPL(comedi_alloc_subdev_readback);

static void comedi_device_detach_cleanup(struct comedi_device *dev)
{
	int i;
	struct comedi_subdevice *s;

	if (dev->subdevices) {
		for (i = 0; i < dev->n_subdevices; i++) {
			s = &dev->subdevices[i];
			if (comedi_can_auto_free_spriv(s))
				kfree(s->private);
			comedi_free_subdevice_minor(s);
			if (s->async) {
				comedi_buf_alloc(dev, s, 0);
				kfree(s->async);
			}
			kfree(s->readback);
		}
		kfree(dev->subdevices);
		dev->subdevices = NULL;
		dev->n_subdevices = 0;
	}
	kfree(dev->private);
	kfree(dev->pacer);
	dev->private = NULL;
	dev->pacer = NULL;
	dev->driver = NULL;
	dev->board_name = NULL;
	dev->board_ptr = NULL;
	dev->mmio = NULL;
	dev->iobase = 0;
	dev->iolen = 0;
	dev->ioenabled = false;
	dev->irq = 0;
	dev->read_subdev = NULL;
	dev->write_subdev = NULL;
	dev->open = NULL;
	dev->close = NULL;
	comedi_clear_hw_dev(dev);
}

void comedi_device_detach(struct comedi_device *dev)
{
	comedi_device_cancel_all(dev);
	down_write(&dev->attach_lock);
	dev->attached = false;
	dev->detach_count++;
	if (dev->driver)
		dev->driver->detach(dev);
	comedi_device_detach_cleanup(dev);
	up_write(&dev->attach_lock);
}

static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s)
{
	return -EINVAL;
}

int insn_inval(struct comedi_device *dev, struct comedi_subdevice *s,
	       struct comedi_insn *insn, unsigned int *data)
{
	return -EINVAL;
}

/**
 * comedi_readback_insn_read() - A generic (*insn_read) for subdevice readback.
 * @dev: COMEDI device.
 * @s: COMEDI subdevice.
 * @insn: COMEDI instruction.
 * @data: Pointer to return the readback data.
 *
 * Handles the %INSN_READ instruction for subdevices that use the readback
 * array allocated by comedi_alloc_subdev_readback().  It may be used
 * directly as the subdevice's handler (@s->insn_read) or called via a
 * wrapper.
 *
 * @insn->n is normally 1, which will read a single value.  If higher, the
 * same element of the readback array will be read multiple times.
 *
 * Returns @insn->n on success, or -EINVAL if @s->readback is NULL.
 */
int comedi_readback_insn_read(struct comedi_device *dev,
			      struct comedi_subdevice *s,
			      struct comedi_insn *insn,
			      unsigned int *data)
{
	unsigned int chan = CR_CHAN(insn->chanspec);
	int i;

	if (!s->readback)
		return -EINVAL;

	for (i = 0; i < insn->n; i++)
		data[i] = s->readback[chan];

	return insn->n;
}
EXPORT_SYMBOL_GPL(comedi_readback_insn_read);

/**
 * comedi_timeout() - Busy-wait for a driver condition to occur
 * @dev: COMEDI device.
 * @s: COMEDI subdevice.
 * @insn: COMEDI instruction.
 * @cb: Callback to check for the condition.
 * @context: Private context from the driver.
 *
 * Busy-waits for up to a second (%COMEDI_TIMEOUT_MS) for the condition or
 * some error (other than -EBUSY) to occur.  The parameters @dev, @s, @insn,
 * and @context are passed to the callback function, which returns -EBUSY to
 * continue waiting or some other value to stop waiting (generally 0 if the
 * condition occurred, or some error value).
 *
 * Returns -ETIMEDOUT if timed out, otherwise the return value from the
 * callback function.
 */
int comedi_timeout(struct comedi_device *dev,
		   struct comedi_subdevice *s,
		   struct comedi_insn *insn,
		   int (*cb)(struct comedi_device *dev,
			     struct comedi_subdevice *s,
			     struct comedi_insn *insn,
			     unsigned long context),
		   unsigned long context)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(COMEDI_TIMEOUT_MS);
	int ret;

	while (time_before(jiffies, timeout)) {
		ret = cb(dev, s, insn, context);
		if (ret != -EBUSY)
			return ret;	/* success (0) or non EBUSY errno */
		cpu_relax();
	}
	return -ETIMEDOUT;
}
EXPORT_SYMBOL_GPL(comedi_timeout);

/**
 * comedi_dio_insn_config() - Boilerplate (*insn_config) for DIO subdevices
 * @dev: COMEDI device.
 * @s: COMEDI subdevice.
 * @insn: COMEDI instruction.
 * @data: Instruction parameters and return data.
 * @mask: io_bits mask for grouped channels, or 0 for single channel.
 *
 * If @mask is 0, it is replaced with a single-bit mask corresponding to the
 * channel number specified by @insn->chanspec.  Otherwise, @mask
 * corresponds to a group of channels (which should include the specified
 * channel) that are always configured together as inputs or outputs.
 *
 * Partially handles the %INSN_CONFIG_DIO_INPUT, %INSN_CONFIG_DIO_OUTPUTS,
 * and %INSN_CONFIG_DIO_QUERY instructions.  The first two update
 * @s->io_bits to record the directions of the masked channels.  The last
 * one sets @data[1] to the current direction of the group of channels
 * (%COMEDI_INPUT) or %COMEDI_OUTPUT) as recorded in @s->io_bits.
 *
 * The caller is responsible for updating the DIO direction in the hardware
 * registers if this function returns 0.
 *
 * Returns 0 for a %INSN_CONFIG_DIO_INPUT or %INSN_CONFIG_DIO_OUTPUT
 * instruction, @insn->n (> 0) for a %INSN_CONFIG_DIO_QUERY instruction, or
 * -EINVAL for some other instruction.
 */
int comedi_dio_insn_config(struct comedi_device *dev,
			   struct comedi_subdevice *s,
			   struct comedi_insn *insn,
			   unsigned int *data,
			   unsigned int mask)
{
	unsigned int chan_mask = 1 << CR_CHAN(insn->chanspec);

	if (!mask)
		mask = chan_mask;

	switch (data[0]) {
	case INSN_CONFIG_DIO_INPUT:
		s->io_bits &= ~mask;
		break;

	case INSN_CONFIG_DIO_OUTPUT:
		s->io_bits |= mask;
		break;

	case INSN_CONFIG_DIO_QUERY:
		data[1] = (s->io_bits & mask) ? COMEDI_OUTPUT : COMEDI_INPUT;
		return insn->n;

	default:
		return -EINVAL;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(comedi_dio_insn_config);

/**
 * comedi_dio_update_state() - Update the internal state of DIO subdevices
 * @s: COMEDI subdevice.
 * @data: The channel mask and bits to update.
 *
 * Updates @s->state which holds the internal state of the outputs for DIO
 * or DO subdevices (up to 32 channels).  @data[0] contains a bit-mask of
 * the channels to be updated.  @data[1] contains a bit-mask of those
 * channels to be set to '1'.  The caller is responsible for updating the
 * outputs in hardware according to @s->state.  As a minimum, the channels
 * in the returned bit-mask need to be updated.
 *
 * Returns @mask with non-existent channels removed.
 */
unsigned int comedi_dio_update_state(struct comedi_subdevice *s,
				     unsigned int *data)
{
	unsigned int chanmask = (s->n_chan < 32) ? ((1 << s->n_chan) - 1)
						 : 0xffffffff;
	unsigned int mask = data[0] & chanmask;
	unsigned int bits = data[1];

	if (mask) {
		s->state &= ~mask;
		s->state |= (bits & mask);
	}

	return mask;
}
EXPORT_SYMBOL_GPL(comedi_dio_update_state);

/**
 * comedi_bytes_per_scan() - Get length of asynchronous command "scan" in bytes
 * @s: COMEDI subdevice.
 *
 * Determines the overall scan length according to the subdevice type and the
 * number of channels in the scan.
 *
 * For digital input, output or input/output subdevices, samples for
 * multiple channels are assumed to be packed into one or more unsigned
 * short or unsigned int values according to the subdevice's %SDF_LSAMPL
 * flag.  For other types of subdevice, samples are assumed to occupy a
 * whole unsigned short or unsigned int according to the %SDF_LSAMPL flag.
 *
 * Returns the overall scan length in bytes.
 */
unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s)
{
	struct comedi_cmd *cmd = &s->async->cmd;
	unsigned int num_samples;
	unsigned int bits_per_sample;

	switch (s->type) {
	case COMEDI_SUBD_DI:
	case COMEDI_SUBD_DO:
	case COMEDI_SUBD_DIO:
		bits_per_sample = 8 * comedi_bytes_per_sample(s);
		num_samples = DIV_ROUND_UP(cmd->scan_end_arg, bits_per_sample);
		break;
	default:
		num_samples = cmd->scan_end_arg;
		break;
	}
	return comedi_samples_to_bytes(s, num_samples);
}
EXPORT_SYMBOL_GPL(comedi_bytes_per_scan);

static unsigned int __comedi_nscans_left(struct comedi_subdevice *s,
					 unsigned int nscans)
{
	struct comedi_async *async = s->async;
	struct comedi_cmd *cmd = &async->cmd;

	if (cmd->stop_src == TRIG_COUNT) {
		unsigned int scans_left = 0;

		if (async->scans_done < cmd->stop_arg)
			scans_left = cmd->stop_arg - async->scans_done;

		if (nscans > scans_left)
			nscans = scans_left;
	}
	return nscans;
}

/**
 * comedi_nscans_left() - Return the number of scans left in the command
 * @s: COMEDI subdevice.
 * @nscans: The expected number of scans or 0 for all available scans.
 *
 * If @nscans is 0, it is set to the number of scans available in the
 * async buffer.
 *
 * If the async command has a stop_src of %TRIG_COUNT, the @nscans will be
 * checked against the number of scans remaining to complete the command.
 *
 * The return value will then be either the expected number of scans or the
 * number of scans remaining to complete the command, whichever is fewer.
 */
unsigned int comedi_nscans_left(struct comedi_subdevice *s,
				unsigned int nscans)
{
	if (nscans == 0) {
		unsigned int nbytes = comedi_buf_read_n_available(s);

		nscans = nbytes / comedi_bytes_per_scan(s);
	}
	return __comedi_nscans_left(s, nscans);
}
EXPORT_SYMBOL_GPL(comedi_nscans_left);

/**
 * comedi_nsamples_left() - Return the number of samples left in the command
 * @s: COMEDI subdevice.
 * @nsamples: The expected number of samples.
 *
 * Returns the number of samples remaining to complete the command, or the
 * specified expected number of samples (@nsamples), whichever is fewer.
 */
unsigned int comedi_nsamples_left(struct comedi_subdevice *s,
				  unsigned int nsamples)
{
	struct comedi_async *async = s->async;
	struct comedi_cmd *cmd = &async->cmd;

	if (cmd->stop_src == TRIG_COUNT) {
		unsigned int nscans = nsamples / cmd->scan_end_arg;
		unsigned int scans_left = __comedi_nscans_left(s, nscans);
		unsigned int scan_pos =
		    comedi_bytes_to_samples(s, async->scan_progress);
		unsigned long long samples_left = 0;

		if (scans_left) {
			samples_left = ((unsigned long long)scans_left *
					cmd->scan_end_arg) - scan_pos;
		}

		if (samples_left < nsamples)
			nsamples = samples_left;
	}
	return nsamples;
}
EXPORT_SYMBOL_GPL(comedi_nsamples_left);

/**
 * comedi_inc_scan_progress() - Update scan progress in asynchronous command
 * @s: COMEDI subdevice.
 * @num_bytes: Amount of data in bytes to increment scan progress.
 *
 * Increments the scan progress by the number of bytes specified by @num_bytes.
 * If the scan progress reaches or exceeds the scan length in bytes, reduce
 * it modulo the scan length in bytes and set the "end of scan" asynchronous
 * event flag (%COMEDI_CB_EOS) to be processed later.
 */
void comedi_inc_scan_progress(struct comedi_subdevice *s,
			      unsigned int num_bytes)
{
	struct comedi_async *async = s->async;
	struct comedi_cmd *cmd = &async->cmd;
	unsigned int scan_length = comedi_bytes_per_scan(s);

	/* track the 'cur_chan' for non-SDF_PACKED subdevices */
	if (!(s->subdev_flags & SDF_PACKED)) {
		async->cur_chan += comedi_bytes_to_samples(s, num_bytes);
		async->cur_chan %= cmd->chanlist_len;
	}

	async->scan_progress += num_bytes;
	if (async->scan_progress >= scan_length) {
		unsigned int nscans = async->scan_progress / scan_length;

		if (async->scans_done < (UINT_MAX - nscans))
			async->scans_done += nscans;
		else
			async->scans_done = UINT_MAX;

		async->scan_progress %= scan_length;
		async->events |= COMEDI_CB_EOS;
	}
}
EXPORT_SYMBOL_GPL(comedi_inc_scan_progress);

/**
 * comedi_handle_events() - Handle events and possibly stop acquisition
 * @dev: COMEDI device.
 * @s: COMEDI subdevice.
 *
 * Handles outstanding asynchronous acquisition event flags associated
 * with the subdevice.  Call the subdevice's @s->cancel() handler if the
 * "end of acquisition", "error" or "overflow" event flags are set in order
 * to stop the acquisition at the driver level.
 *
 * Calls comedi_event() to further process the event flags, which may mark
 * the asynchronous command as no longer running, possibly terminated with
 * an error, and may wake up tasks.
 *
 * Return a bit-mask of the handled events.
 */
unsigned int comedi_handle_events(struct comedi_device *dev,
				  struct comedi_subdevice *s)
{
	unsigned int events = s->async->events;

	if (events == 0)
		return events;

	if ((events & COMEDI_CB_CANCEL_MASK) && s->cancel)
		s->cancel(dev, s);

	comedi_event(dev, s);

	return events;
}
EXPORT_SYMBOL_GPL(comedi_handle_events);

static int insn_rw_emulate_bits(struct comedi_device *dev,
				struct comedi_subdevice *s,
				struct comedi_insn *insn,
				unsigned int *data)
{
	struct comedi_insn _insn;
	unsigned int chan = CR_CHAN(insn->chanspec);
	unsigned int base_chan = (chan < 32) ? 0 : chan;
	unsigned int _data[2];
	int ret;

	memset(_data, 0, sizeof(_data));
	memset(&_insn, 0, sizeof(_insn));
	_insn.insn = INSN_BITS;
	_insn.chanspec = base_chan;
	_insn.n = 2;
	_insn.subdev = insn->subdev;

	if (insn->insn == INSN_WRITE) {
		if (!(s->subdev_flags & SDF_WRITABLE))
			return -EINVAL;
		_data[0] = 1 << (chan - base_chan);		    /* mask */
		_data[1] = data[0] ? (1 << (chan - base_chan)) : 0; /* bits */
	}

	ret = s->insn_bits(dev, s, &_insn, _data);
	if (ret < 0)
		return ret;

	if (insn->insn == INSN_READ)
		data[0] = (_data[1] >> (chan - base_chan)) & 1;

	return 1;
}

static int __comedi_device_postconfig_async(struct comedi_device *dev,
					    struct comedi_subdevice *s)
{
	struct comedi_async *async;
	unsigned int buf_size;
	int ret;

	if ((s->subdev_flags & (SDF_CMD_READ | SDF_CMD_WRITE)) == 0) {
		dev_warn(dev->class_dev,
			 "async subdevices must support SDF_CMD_READ or SDF_CMD_WRITE\n");
		return -EINVAL;
	}
	if (!s->do_cmdtest) {
		dev_warn(dev->class_dev,
			 "async subdevices must have a do_cmdtest() function\n");
		return -EINVAL;
	}
	if (!s->cancel)
		dev_warn(dev->class_dev,
			 "async subdevices should have a cancel() function\n");

	async = kzalloc(sizeof(*async), GFP_KERNEL);
	if (!async)
		return -ENOMEM;

	init_waitqueue_head(&async->wait_head);
	s->async = async;

	async->max_bufsize = comedi_default_buf_maxsize_kb * 1024;
	buf_size = comedi_default_buf_size_kb * 1024;
	if (buf_size > async->max_bufsize)
		buf_size = async->max_bufsize;

	if (comedi_buf_alloc(dev, s, buf_size) < 0) {
		dev_warn(dev->class_dev, "Buffer allocation failed\n");
		return -ENOMEM;
	}
	if (s->buf_change) {
		ret = s->buf_change(dev, s);
		if (ret < 0)
			return ret;
	}

	comedi_alloc_subdevice_minor(s);

	return 0;
}

static int __comedi_device_postconfig(struct comedi_device *dev)
{
	struct comedi_subdevice *s;
	int ret;
	int i;

	for (i = 0; i < dev->n_subdevices; i++) {
		s = &dev->subdevices[i];

		if (s->type == COMEDI_SUBD_UNUSED)
			continue;

		if (s->type == COMEDI_SUBD_DO) {
			if (s->n_chan < 32)
				s->io_bits = (1 << s->n_chan) - 1;
			else
				s->io_bits = 0xffffffff;
		}

		if (s->len_chanlist == 0)
			s->len_chanlist = 1;

		if (s->do_cmd) {
			ret = __comedi_device_postconfig_async(dev, s);
			if (ret)
				return ret;
		}

		if (!s->range_table && !s->range_table_list)
			s->range_table = &range_unknown;

		if (!s->insn_read && s->insn_bits)
			s->insn_read = insn_rw_emulate_bits;
		if (!s->insn_write && s->insn_bits)
			s->insn_write = insn_rw_emulate_bits;

		if (!s->insn_read)
			s->insn_read = insn_inval;
		if (!s->insn_write)
			s->insn_write = insn_inval;
		if (!s->insn_bits)
			s->insn_bits = insn_inval;
		if (!s->insn_config)
			s->insn_config = insn_inval;

		if (!s->poll)
			s->poll = poll_invalid;
	}

	return 0;
}

/* do a little post-config cleanup */
static int comedi_device_postconfig(struct comedi_device *dev)
{
	int ret;

	ret = __comedi_device_postconfig(dev);
	if (ret < 0)
		return ret;
	down_write(&dev->attach_lock);
	dev->attached = true;
	up_write(&dev->attach_lock);
	return 0;
}

/*
 * Generic recognize function for drivers that register their supported
 * board names.
 *
 * 'driv->board_name' points to a 'const char *' member within the
 * zeroth element of an array of some private board information
 * structure, say 'struct foo_board' containing a member 'const char
 * *board_name' that is initialized to point to a board name string that
 * is one of the candidates matched against this function's 'name'
 * parameter.
 *
 * 'driv->offset' is the size of the private board information
 * structure, say 'sizeof(struct foo_board)', and 'driv->num_names' is
 * the length of the array of private board information structures.
 *
 * If one of the board names in the array of private board information
 * structures matches the name supplied to this function, the function
 * returns a pointer to the pointer to the board name, otherwise it
 * returns NULL.  The return value ends up in the 'board_ptr' member of
 * a 'struct comedi_device' that the low-level comedi driver's
 * 'attach()' hook can convert to a point to a particular element of its
 * array of private board information structures by subtracting the
 * offset of the member that points to the board name.  (No subtraction
 * is required if the board name pointer is the first member of the
 * private board information structure, which is generally the case.)
 */
static void *comedi_recognize(struct comedi_driver *driv, const char *name)
{
	char **name_ptr = (char **)driv->board_name;
	int i;

	for (i = 0; i < driv->num_names; i++) {
		if (strcmp(*name_ptr, name) == 0)
			return name_ptr;
		name_ptr = (void *)name_ptr + driv->offset;
	}

	return NULL;
}

static void comedi_report_boards(struct comedi_driver *driv)
{
	unsigned int i;
	const char *const *name_ptr;

	pr_info("comedi: valid board names for %s driver are:\n",
		driv->driver_name);

	name_ptr = driv->board_name;
	for (i = 0; i < driv->num_names; i++) {
		pr_info(" %s\n", *name_ptr);
		name_ptr = (const char **)((char *)name_ptr + driv->offset);
	}

	if (driv->num_names == 0)
		pr_info(" %s\n", driv->driver_name);
}

/**
 * comedi_load_firmware() - Request and load firmware for a device
 * @dev: COMEDI device.
 * @device: Hardware device.
 * @name: The name of the firmware image.
 * @cb: Callback to the upload the firmware image.
 * @context: Private context from the driver.
 *
 * Sends a firmware request for the hardware device and waits for it.  Calls
 * the callback function to upload the firmware to the device, them releases
 * the firmware.
 *
 * Returns 0 on success, -EINVAL if @cb is NULL, or a negative error number
 * from the firmware request or the callback function.
 */
int comedi_load_firmware(struct comedi_device *dev,
			 struct device *device,
			 const char *name,
			 int (*cb)(struct comedi_device *dev,
				   const u8 *data, size_t size,
				   unsigned long context),
			 unsigned long context)
{
	const struct firmware *fw;
	int ret;

	if (!cb)
		return -EINVAL;

	ret = request_firmware(&fw, name, device);
	if (ret == 0) {
		ret = cb(dev, fw->data, fw->size, context);
		release_firmware(fw);
	}

	return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(comedi_load_firmware);

/**
 * __comedi_request_region() - Request an I/O region for a legacy driver
 * @dev: COMEDI device.
 * @start: Base address of the I/O region.
 * @len: Length of the I/O region.
 *
 * Requests the specified I/O port region which must start at a non-zero
 * address.
 *
 * Returns 0 on success, -EINVAL if @start is 0, or -EIO if the request
 * fails.
 */
int __comedi_request_region(struct comedi_device *dev,
			    unsigned long start, unsigned long len)
{
	if (!start) {
		dev_warn(dev->class_dev,
			 "%s: a I/O base address must be specified\n",
			 dev->board_name);
		return -EINVAL;
	}

	if (!request_region(start, len, dev->board_name)) {
		dev_warn(dev->class_dev, "%s: I/O port conflict (%#lx,%lu)\n",
			 dev->board_name, start, len);
		return -EIO;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(__comedi_request_region);

/**
 * comedi_request_region() - Request an I/O region for a legacy driver
 * @dev: COMEDI device.
 * @start: Base address of the I/O region.
 * @len: Length of the I/O region.
 *
 * Requests the specified I/O port region which must start at a non-zero
 * address.
 *
 * On success, @dev->iobase is set to the base address of the region and
 * @dev->iolen is set to its length.
 *
 * Returns 0 on success, -EINVAL if @start is 0, or -EIO if the request
 * fails.
 */
int comedi_request_region(struct comedi_device *dev,
			  unsigned long start, unsigned long len)
{
	int ret;

	ret = __comedi_request_region(dev, start, len);
	if (ret == 0) {
		dev->iobase = start;
		dev->iolen = len;
	}

	return ret;
}
EXPORT_SYMBOL_GPL(comedi_request_region);

/**
 * comedi_legacy_detach() - A generic (*detach) function for legacy drivers
 * @dev: COMEDI device.
 *
 * This is a simple, generic 'detach' handler for legacy COMEDI devices that
 * just use a single I/O port region and possibly an IRQ and that don't need
 * any special clean-up for their private device or subdevice storage.  It
 * can also be called by a driver-specific 'detach' handler.
 *
 * If @dev->irq is non-zero, the IRQ will be freed.  If @dev->iobase and
 * @dev->iolen are both non-zero, the I/O port region will be released.
 */
void comedi_legacy_detach(struct comedi_device *dev)
{
	if (dev->irq) {
		free_irq(dev->irq, dev);
		dev->irq = 0;
	}
	if (dev->iobase && dev->iolen) {
		release_region(dev->iobase, dev->iolen);
		dev->iobase = 0;
		dev->iolen = 0;
	}
}
EXPORT_SYMBOL_GPL(comedi_legacy_detach);

int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
	struct comedi_driver *driv;
	int ret;

	if (dev->attached)
		return -EBUSY;

	mutex_lock(&comedi_drivers_list_lock);
	for (driv = comedi_drivers; driv; driv = driv->next) {
		if (!try_module_get(driv->module))
			continue;
		if (driv->num_names) {
			dev->board_ptr = comedi_recognize(driv, it->board_name);
			if (dev->board_ptr)
				break;
		} else if (strcmp(driv->driver_name, it->board_name) == 0) {
			break;
		}
		module_put(driv->module);
	}
	if (!driv) {
		/*  recognize has failed if we get here */
		/*  report valid board names before returning error */
		for (driv = comedi_drivers; driv; driv = driv->next) {
			if (!try_module_get(driv->module))
				continue;
			comedi_report_boards(driv);
			module_put(driv->module);
		}
		ret = -EIO;
		goto out;
	}
	if (!driv->attach) {
		/* driver does not support manual configuration */
		dev_warn(dev->class_dev,
			 "driver '%s' does not support attach using comedi_config\n",
			 driv->driver_name);
		module_put(driv->module);
		ret = -EIO;
		goto out;
	}
	dev->driver = driv;
	dev->board_name = dev->board_ptr ? *(const char **)dev->board_ptr
					 : dev->driver->driver_name;
	ret = driv->attach(dev, it);
	if (ret >= 0)
		ret = comedi_device_postconfig(dev);
	if (ret < 0) {
		comedi_device_detach(dev);
		module_put(driv->module);
	}
	/* On success, the driver module count has been incremented. */
out:
	mutex_unlock(&comedi_drivers_list_lock);
	return ret;
}

/**
 * comedi_auto_config() - Create a COMEDI device for a hardware device
 * @hardware_device: Hardware device.
 * @driver: COMEDI low-level driver for the hardware device.
 * @context: Driver context for the auto_attach handler.
 *
 * Allocates a new COMEDI device for the hardware device and calls the
 * low-level driver's 'auto_attach' handler to set-up the hardware and
 * allocate the COMEDI subdevices.  Additional "post-configuration" setting
 * up is performed on successful return from the 'auto_attach' handler.
 * If the 'auto_attach' handler fails, the low-level driver's 'detach'
 * handler will be called as part of the clean-up.
 *
 * This is usually called from a wrapper function in a bus-specific COMEDI
 * module, which in turn is usually called from a bus device 'probe'
 * function in the low-level driver.
 *
 * Returns 0 on success, -EINVAL if the parameters are invalid or the
 * post-configuration determines the driver has set the COMEDI device up
 * incorrectly, -ENOMEM if failed to allocate memory, -EBUSY if run out of
 * COMEDI minor device numbers, or some negative error number returned by
 * the driver's 'auto_attach' handler.
 */
int comedi_auto_config(struct device *hardware_device,
		       struct comedi_driver *driver, unsigned long context)
{
	struct comedi_device *dev;
	int ret;

	if (!hardware_device) {
		pr_warn("BUG! comedi_auto_config called with NULL hardware_device\n");
		return -EINVAL;
	}
	if (!driver) {
		dev_warn(hardware_device,
			 "BUG! comedi_auto_config called with NULL comedi driver\n");
		return -EINVAL;
	}

	if (!driver->auto_attach) {
		dev_warn(hardware_device,
			 "BUG! comedi driver '%s' has no auto_attach handler\n",
			 driver->driver_name);
		return -EINVAL;
	}

	dev = comedi_alloc_board_minor(hardware_device);
	if (IS_ERR(dev)) {
		dev_warn(hardware_device,
			 "driver '%s' could not create device.\n",
			 driver->driver_name);
		return PTR_ERR(dev);
	}
	/* Note: comedi_alloc_board_minor() locked dev->mutex. */

	dev->driver = driver;
	dev->board_name = dev->driver->driver_name;
	ret = driver->auto_attach(dev, context);
	if (ret >= 0)
		ret = comedi_device_postconfig(dev);
	mutex_unlock(&dev->mutex);

	if (ret < 0) {
		dev_warn(hardware_device,
			 "driver '%s' failed to auto-configure device.\n",
			 driver->driver_name);
		comedi_release_hardware_device(hardware_device);
	} else {
		/*
		 * class_dev should be set properly here
		 *  after a successful auto config
		 */
		dev_info(dev->class_dev,
			 "driver '%s' has successfully auto-configured '%s'.\n",
			 driver->driver_name, dev->board_name);
	}
	return ret;
}
EXPORT_SYMBOL_GPL(comedi_auto_config);

/**
 * comedi_auto_unconfig() - Unconfigure auto-allocated COMEDI device
 * @hardware_device: Hardware device previously passed to
 *                   comedi_auto_config().
 *
 * Cleans up and eventually destroys the COMEDI device allocated by
 * comedi_auto_config() for the same hardware device.  As part of this
 * clean-up, the low-level COMEDI driver's 'detach' handler will be called.
 * (The COMEDI device itself will persist in an unattached state if it is
 * still open, until it is released, and any mmapped buffers will persist
 * until they are munmapped.)
 *
 * This is usually called from a wrapper module in a bus-specific COMEDI
 * module, which in turn is usually set as the bus device 'remove' function
 * in the low-level COMEDI driver.
 */
void comedi_auto_unconfig(struct device *hardware_device)
{
	if (!hardware_device)
		return;
	comedi_release_hardware_device(hardware_device);
}
EXPORT_SYMBOL_GPL(comedi_auto_unconfig);

/**
 * comedi_driver_register() - Register a low-level COMEDI driver
 * @driver: Low-level COMEDI driver.
 *
 * The low-level COMEDI driver is added to the list of registered COMEDI
 * drivers.  This is used by the handler for the "/proc/comedi" file and is
 * also used by the handler for the %COMEDI_DEVCONFIG ioctl to configure
 * "legacy" COMEDI devices (for those low-level drivers that support it).
 *
 * Returns 0.
 */
int comedi_driver_register(struct comedi_driver *driver)
{
	mutex_lock(&comedi_drivers_list_lock);
	driver->next = comedi_drivers;
	comedi_drivers = driver;
	mutex_unlock(&comedi_drivers_list_lock);

	return 0;
}
EXPORT_SYMBOL_GPL(comedi_driver_register);

/**
 * comedi_driver_unregister() - Unregister a low-level COMEDI driver
 * @driver: Low-level COMEDI driver.
 *
 * The low-level COMEDI driver is removed from the list of registered COMEDI
 * drivers.  Detaches any COMEDI devices attached to the driver, which will
 * result in the low-level driver's 'detach' handler being called for those
 * devices before this function returns.
 */
void comedi_driver_unregister(struct comedi_driver *driver)
{
	struct comedi_driver *prev;
	int i;

	/* unlink the driver */
	mutex_lock(&comedi_drivers_list_lock);
	if (comedi_drivers == driver) {
		comedi_drivers = driver->next;
	} else {
		for (prev = comedi_drivers; prev->next; prev = prev->next) {
			if (prev->next == driver) {
				prev->next = driver->next;
				break;
			}
		}
	}
	mutex_unlock(&comedi_drivers_list_lock);

	/* check for devices using this driver */
	for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
		struct comedi_device *dev = comedi_dev_get_from_minor(i);

		if (!dev)
			continue;

		mutex_lock(&dev->mutex);
		if (dev->attached && dev->driver == driver) {
			if (dev->use_count)
				dev_warn(dev->class_dev,
					 "BUG! detaching device with use_count=%d\n",
					 dev->use_count);
			comedi_device_detach(dev);
		}
		mutex_unlock(&dev->mutex);
		comedi_dev_put(dev);
	}
}
EXPORT_SYMBOL_GPL(comedi_driver_unregister);