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
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Framework to handle complex IIO aggregate devices.
*
* The typical architecture is to have one device as the frontend device which
* can be "linked" against one or multiple backend devices. All the IIO and
* userspace interface is expected to be registers/managed by the frontend
* device which will callback into the backends when needed (to get/set some
* configuration that it does not directly control).
*
* -------------------------------------------------------
* ------------------ | ------------ ------------ ------- FPGA|
* | ADC |------------------------| | ADC CORE |---------| DMA CORE |------| RAM | |
* | (Frontend/IIO) | Serial Data (eg: LVDS) | |(backend) |---------| |------| | |
* | |------------------------| ------------ ------------ ------- |
* ------------------ -------------------------------------------------------
*
* The framework interface is pretty simple:
* - Backends should register themselves with devm_iio_backend_register()
* - Frontend devices should get backends with devm_iio_backend_get()
*
* Also to note that the primary target for this framework are converters like
* ADC/DACs so iio_backend_ops will have some operations typical of converter
* devices. On top of that, this is "generic" for all IIO which means any kind
* of device can make use of the framework. That said, If the iio_backend_ops
* struct begins to grow out of control, we can always refactor things so that
* the industrialio-backend.c is only left with the really generic stuff. Then,
* we can build on top of it depending on the needs.
*
* Copyright (C) 2023-2024 Analog Devices Inc.
*/
#define dev_fmt(fmt) "iio-backend: " fmt
#include <linux/cleanup.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/stringify.h>
#include <linux/types.h>
#include <linux/iio/backend.h>
#include <linux/iio/iio.h>
struct iio_backend {
struct list_head entry;
const struct iio_backend_ops *ops;
struct device *frontend_dev;
struct device *dev;
struct module *owner;
void *priv;
const char *name;
unsigned int cached_reg_addr;
/*
* This index is relative to the frontend. Meaning that for
* frontends with multiple backends, this will be the index of this
* backend. Used for the debugfs directory name.
*/
u8 idx;
};
/*
* Helper struct for requesting buffers. This ensures that we have all data
* that we need to free the buffer in a device managed action.
*/
struct iio_backend_buffer_pair {
struct iio_backend *back;
struct iio_buffer *buffer;
};
static LIST_HEAD(iio_back_list);
static DEFINE_MUTEX(iio_back_lock);
/*
* Helper macros to call backend ops. Makes sure the option is supported.
*/
#define iio_backend_check_op(back, op) ({ \
struct iio_backend *____back = back; \
int ____ret = 0; \
\
if (!____back->ops->op) \
____ret = -EOPNOTSUPP; \
\
____ret; \
})
#define iio_backend_op_call(back, op, args...) ({ \
struct iio_backend *__back = back; \
int __ret; \
\
__ret = iio_backend_check_op(__back, op); \
if (!__ret) \
__ret = __back->ops->op(__back, ##args); \
\
__ret; \
})
#define iio_backend_ptr_op_call(back, op, args...) ({ \
struct iio_backend *__back = back; \
void *ptr_err; \
int __ret; \
\
__ret = iio_backend_check_op(__back, op); \
if (__ret) \
ptr_err = ERR_PTR(__ret); \
else \
ptr_err = __back->ops->op(__back, ##args); \
\
ptr_err; \
})
#define iio_backend_void_op_call(back, op, args...) { \
struct iio_backend *__back = back; \
int __ret; \
\
__ret = iio_backend_check_op(__back, op); \
if (!__ret) \
__back->ops->op(__back, ##args); \
else \
dev_dbg(__back->dev, "Op(%s) not implemented\n",\
__stringify(op)); \
}
static ssize_t iio_backend_debugfs_read_reg(struct file *file,
char __user *userbuf,
size_t count, loff_t *ppos)
{
struct iio_backend *back = file->private_data;
char read_buf[20];
unsigned int val;
int ret, len;
ret = iio_backend_op_call(back, debugfs_reg_access,
back->cached_reg_addr, 0, &val);
if (ret)
return ret;
len = scnprintf(read_buf, sizeof(read_buf), "0x%X\n", val);
return simple_read_from_buffer(userbuf, count, ppos, read_buf, len);
}
static ssize_t iio_backend_debugfs_write_reg(struct file *file,
const char __user *userbuf,
size_t count, loff_t *ppos)
{
struct iio_backend *back = file->private_data;
unsigned int val;
char buf[80];
ssize_t rc;
int ret;
rc = simple_write_to_buffer(buf, sizeof(buf), ppos, userbuf, count);
if (rc < 0)
return rc;
ret = sscanf(buf, "%i %i", &back->cached_reg_addr, &val);
switch (ret) {
case 1:
return count;
case 2:
ret = iio_backend_op_call(back, debugfs_reg_access,
back->cached_reg_addr, val, NULL);
if (ret)
return ret;
return count;
default:
return -EINVAL;
}
}
static const struct file_operations iio_backend_debugfs_reg_fops = {
.open = simple_open,
.read = iio_backend_debugfs_read_reg,
.write = iio_backend_debugfs_write_reg,
};
static ssize_t iio_backend_debugfs_read_name(struct file *file,
char __user *userbuf,
size_t count, loff_t *ppos)
{
struct iio_backend *back = file->private_data;
char name[128];
int len;
len = scnprintf(name, sizeof(name), "%s\n", back->name);
return simple_read_from_buffer(userbuf, count, ppos, name, len);
}
static const struct file_operations iio_backend_debugfs_name_fops = {
.open = simple_open,
.read = iio_backend_debugfs_read_name,
};
/**
* iio_backend_debugfs_add - Add debugfs interfaces for Backends
* @back: Backend device
* @indio_dev: IIO device
*/
void iio_backend_debugfs_add(struct iio_backend *back,
struct iio_dev *indio_dev)
{
struct dentry *d = iio_get_debugfs_dentry(indio_dev);
struct dentry *back_d;
char name[128];
if (!IS_ENABLED(CONFIG_DEBUG_FS) || !d)
return;
if (!back->ops->debugfs_reg_access && !back->name)
return;
snprintf(name, sizeof(name), "backend%d", back->idx);
back_d = debugfs_create_dir(name, d);
if (IS_ERR(back_d))
return;
if (back->ops->debugfs_reg_access)
debugfs_create_file("direct_reg_access", 0600, back_d, back,
&iio_backend_debugfs_reg_fops);
if (back->name)
debugfs_create_file("name", 0400, back_d, back,
&iio_backend_debugfs_name_fops);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_debugfs_add, "IIO_BACKEND");
/**
* iio_backend_debugfs_print_chan_status - Print channel status
* @back: Backend device
* @chan: Channel number
* @buf: Buffer where to print the status
* @len: Available space
*
* One usecase where this is useful is for testing test tones in a digital
* interface and "ask" the backend to dump more details on why a test tone might
* have errors.
*
* RETURNS:
* Number of copied bytes on success, negative error code on failure.
*/
ssize_t iio_backend_debugfs_print_chan_status(struct iio_backend *back,
unsigned int chan, char *buf,
size_t len)
{
if (!IS_ENABLED(CONFIG_DEBUG_FS))
return -ENODEV;
return iio_backend_op_call(back, debugfs_print_chan_status, chan, buf,
len);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_debugfs_print_chan_status, "IIO_BACKEND");
/**
* iio_backend_chan_enable - Enable a backend channel
* @back: Backend device
* @chan: Channel number
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan)
{
return iio_backend_op_call(back, chan_enable, chan);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_chan_enable, "IIO_BACKEND");
/**
* iio_backend_chan_disable - Disable a backend channel
* @back: Backend device
* @chan: Channel number
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_chan_disable(struct iio_backend *back, unsigned int chan)
{
return iio_backend_op_call(back, chan_disable, chan);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_chan_disable, "IIO_BACKEND");
static void __iio_backend_disable(void *back)
{
iio_backend_void_op_call(back, disable);
}
/**
* iio_backend_disable - Backend disable
* @back: Backend device
*/
void iio_backend_disable(struct iio_backend *back)
{
__iio_backend_disable(back);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_disable, "IIO_BACKEND");
/**
* iio_backend_enable - Backend enable
* @back: Backend device
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_enable(struct iio_backend *back)
{
return iio_backend_op_call(back, enable);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_enable, "IIO_BACKEND");
/**
* devm_iio_backend_enable - Device managed backend enable
* @dev: Consumer device for the backend
* @back: Backend device
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int devm_iio_backend_enable(struct device *dev, struct iio_backend *back)
{
int ret;
ret = iio_backend_enable(back);
if (ret)
return ret;
return devm_add_action_or_reset(dev, __iio_backend_disable, back);
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_enable, "IIO_BACKEND");
/**
* iio_backend_data_format_set - Configure the channel data format
* @back: Backend device
* @chan: Channel number
* @data: Data format
*
* Properly configure a channel with respect to the expected data format. A
* @struct iio_backend_data_fmt must be passed with the settings.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan,
const struct iio_backend_data_fmt *data)
{
if (!data || data->type >= IIO_BACKEND_DATA_TYPE_MAX)
return -EINVAL;
return iio_backend_op_call(back, data_format_set, chan, data);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_data_format_set, "IIO_BACKEND");
/**
* iio_backend_data_source_set - Select data source
* @back: Backend device
* @chan: Channel number
* @data: Data source
*
* A given backend may have different sources to stream/sync data. This allows
* to choose that source.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_data_source_set(struct iio_backend *back, unsigned int chan,
enum iio_backend_data_source data)
{
if (data >= IIO_BACKEND_DATA_SOURCE_MAX)
return -EINVAL;
return iio_backend_op_call(back, data_source_set, chan, data);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_data_source_set, "IIO_BACKEND");
/**
* iio_backend_set_sampling_freq - Set channel sampling rate
* @back: Backend device
* @chan: Channel number
* @sample_rate_hz: Sample rate
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_set_sampling_freq(struct iio_backend *back, unsigned int chan,
u64 sample_rate_hz)
{
return iio_backend_op_call(back, set_sample_rate, chan, sample_rate_hz);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_set_sampling_freq, "IIO_BACKEND");
/**
* iio_backend_test_pattern_set - Configure a test pattern
* @back: Backend device
* @chan: Channel number
* @pattern: Test pattern
*
* Configure a test pattern on the backend. This is typically used for
* calibrating the timings on the data digital interface.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_test_pattern_set(struct iio_backend *back,
unsigned int chan,
enum iio_backend_test_pattern pattern)
{
if (pattern >= IIO_BACKEND_TEST_PATTERN_MAX)
return -EINVAL;
return iio_backend_op_call(back, test_pattern_set, chan, pattern);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_test_pattern_set, "IIO_BACKEND");
/**
* iio_backend_chan_status - Get the channel status
* @back: Backend device
* @chan: Channel number
* @error: Error indication
*
* Get the current state of the backend channel. Typically used to check if
* there were any errors sending/receiving data.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_chan_status(struct iio_backend *back, unsigned int chan,
bool *error)
{
return iio_backend_op_call(back, chan_status, chan, error);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_chan_status, "IIO_BACKEND");
/**
* iio_backend_iodelay_set - Set digital I/O delay
* @back: Backend device
* @lane: Lane number
* @taps: Number of taps
*
* Controls delays on sending/receiving data. One usecase for this is to
* calibrate the data digital interface so we get the best results when
* transferring data. Note that @taps has no unit since the actual delay per tap
* is very backend specific. Hence, frontend devices typically should go through
* an array of @taps (the size of that array should typically match the size of
* calibration points on the frontend device) and call this API.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_iodelay_set(struct iio_backend *back, unsigned int lane,
unsigned int taps)
{
return iio_backend_op_call(back, iodelay_set, lane, taps);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_iodelay_set, "IIO_BACKEND");
/**
* iio_backend_data_sample_trigger - Control when to sample data
* @back: Backend device
* @trigger: Data trigger
*
* Mostly useful for input backends. Configures the backend for when to sample
* data (eg: rising vs falling edge).
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_data_sample_trigger(struct iio_backend *back,
enum iio_backend_sample_trigger trigger)
{
if (trigger >= IIO_BACKEND_SAMPLE_TRIGGER_MAX)
return -EINVAL;
return iio_backend_op_call(back, data_sample_trigger, trigger);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_data_sample_trigger, "IIO_BACKEND");
static void iio_backend_free_buffer(void *arg)
{
struct iio_backend_buffer_pair *pair = arg;
iio_backend_void_op_call(pair->back, free_buffer, pair->buffer);
}
/**
* devm_iio_backend_request_buffer - Device managed buffer request
* @dev: Consumer device for the backend
* @back: Backend device
* @indio_dev: IIO device
*
* Request an IIO buffer from the backend. The type of the buffer (typically
* INDIO_BUFFER_HARDWARE) is up to the backend to decide. This is because,
* normally, the backend dictates what kind of buffering we can get.
*
* The backend .free_buffer() hooks is automatically called on @dev detach.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int devm_iio_backend_request_buffer(struct device *dev,
struct iio_backend *back,
struct iio_dev *indio_dev)
{
struct iio_backend_buffer_pair *pair;
struct iio_buffer *buffer;
pair = devm_kzalloc(dev, sizeof(*pair), GFP_KERNEL);
if (!pair)
return -ENOMEM;
buffer = iio_backend_ptr_op_call(back, request_buffer, indio_dev);
if (IS_ERR(buffer))
return PTR_ERR(buffer);
/* weak reference should be all what we need */
pair->back = back;
pair->buffer = buffer;
return devm_add_action_or_reset(dev, iio_backend_free_buffer, pair);
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_request_buffer, "IIO_BACKEND");
/**
* iio_backend_read_raw - Read a channel attribute from a backend device.
* @back: Backend device
* @chan: IIO channel reference
* @val: First returned value
* @val2: Second returned value
* @mask: Specify the attribute to return
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_read_raw(struct iio_backend *back,
struct iio_chan_spec const *chan, int *val, int *val2,
long mask)
{
return iio_backend_op_call(back, read_raw, chan, val, val2, mask);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_read_raw, "IIO_BACKEND");
static struct iio_backend *iio_backend_from_indio_dev_parent(const struct device *dev)
{
struct iio_backend *back = ERR_PTR(-ENODEV), *iter;
/*
* We deliberately go through all backends even after finding a match.
* The reason is that we want to catch frontend devices which have more
* than one backend in which case returning the first we find is bogus.
* For those cases, frontends need to explicitly define
* get_iio_backend() in struct iio_info.
*/
guard(mutex)(&iio_back_lock);
list_for_each_entry(iter, &iio_back_list, entry) {
if (dev == iter->frontend_dev) {
if (!IS_ERR(back)) {
dev_warn(dev,
"Multiple backends! get_iio_backend() needs to be implemented");
return ERR_PTR(-ENODEV);
}
back = iter;
}
}
return back;
}
/**
* iio_backend_ext_info_get - IIO ext_info read callback
* @indio_dev: IIO device
* @private: Data private to the driver
* @chan: IIO channel
* @buf: Buffer where to place the attribute data
*
* This helper is intended to be used by backends that extend an IIO channel
* (through iio_backend_extend_chan_spec()) with extended info. In that case,
* backends are not supposed to give their own callbacks (as they would not have
* a way to get the backend from indio_dev). This is the getter.
*
* RETURNS:
* Number of bytes written to buf, negative error number on failure.
*/
ssize_t iio_backend_ext_info_get(struct iio_dev *indio_dev, uintptr_t private,
const struct iio_chan_spec *chan, char *buf)
{
struct iio_backend *back;
/*
* The below should work for the majority of the cases. It will not work
* when one frontend has multiple backends in which case we'll need a
* new callback in struct iio_info so we can directly request the proper
* backend from the frontend. Anyways, let's only introduce new options
* when really needed...
*/
back = iio_backend_from_indio_dev_parent(indio_dev->dev.parent);
if (IS_ERR(back))
return PTR_ERR(back);
return iio_backend_op_call(back, ext_info_get, private, chan, buf);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_ext_info_get, "IIO_BACKEND");
/**
* iio_backend_ext_info_set - IIO ext_info write callback
* @indio_dev: IIO device
* @private: Data private to the driver
* @chan: IIO channel
* @buf: Buffer holding the sysfs attribute
* @len: Buffer length
*
* This helper is intended to be used by backends that extend an IIO channel
* (trough iio_backend_extend_chan_spec()) with extended info. In that case,
* backends are not supposed to give their own callbacks (as they would not have
* a way to get the backend from indio_dev). This is the setter.
*
* RETURNS:
* Buffer length on success, negative error number on failure.
*/
ssize_t iio_backend_ext_info_set(struct iio_dev *indio_dev, uintptr_t private,
const struct iio_chan_spec *chan,
const char *buf, size_t len)
{
struct iio_backend *back;
back = iio_backend_from_indio_dev_parent(indio_dev->dev.parent);
if (IS_ERR(back))
return PTR_ERR(back);
return iio_backend_op_call(back, ext_info_set, private, chan, buf, len);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_ext_info_set, "IIO_BACKEND");
/**
* iio_backend_extend_chan_spec - Extend an IIO channel
* @back: Backend device
* @chan: IIO channel
*
* Some backends may have their own functionalities and hence capable of
* extending a frontend's channel.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_extend_chan_spec(struct iio_backend *back,
struct iio_chan_spec *chan)
{
const struct iio_chan_spec_ext_info *frontend_ext_info = chan->ext_info;
const struct iio_chan_spec_ext_info *back_ext_info;
int ret;
ret = iio_backend_op_call(back, extend_chan_spec, chan);
if (ret)
return ret;
/*
* Let's keep things simple for now. Don't allow to overwrite the
* frontend's extended info. If ever needed, we can support appending
* it.
*/
if (frontend_ext_info && chan->ext_info != frontend_ext_info)
return -EOPNOTSUPP;
if (!chan->ext_info)
return 0;
/* Don't allow backends to get creative and force their own handlers */
for (back_ext_info = chan->ext_info; back_ext_info->name; back_ext_info++) {
if (back_ext_info->read != iio_backend_ext_info_get)
return -EINVAL;
if (back_ext_info->write != iio_backend_ext_info_set)
return -EINVAL;
}
return 0;
}
EXPORT_SYMBOL_NS_GPL(iio_backend_extend_chan_spec, "IIO_BACKEND");
static void iio_backend_release(void *arg)
{
struct iio_backend *back = arg;
module_put(back->owner);
}
static int __devm_iio_backend_get(struct device *dev, struct iio_backend *back)
{
struct device_link *link;
int ret;
/*
* Make sure the provider cannot be unloaded before the consumer module.
* Note that device_links would still guarantee that nothing is
* accessible (and breaks) but this makes it explicit that the consumer
* module must be also unloaded.
*/
if (!try_module_get(back->owner))
return dev_err_probe(dev, -ENODEV,
"Cannot get module reference\n");
ret = devm_add_action_or_reset(dev, iio_backend_release, back);
if (ret)
return ret;
link = device_link_add(dev, back->dev, DL_FLAG_AUTOREMOVE_CONSUMER);
if (!link)
return dev_err_probe(dev, -EINVAL,
"Could not link to supplier(%s)\n",
dev_name(back->dev));
back->frontend_dev = dev;
dev_dbg(dev, "Found backend(%s) device\n", dev_name(back->dev));
return 0;
}
/**
* iio_backend_ddr_enable - Enable interface DDR (Double Data Rate) mode
* @back: Backend device
*
* Enable DDR, data is generated by the IP at each front (raising and falling)
* of the bus clock signal.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_ddr_enable(struct iio_backend *back)
{
return iio_backend_op_call(back, ddr_enable);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_ddr_enable, "IIO_BACKEND");
/**
* iio_backend_ddr_disable - Disable interface DDR (Double Data Rate) mode
* @back: Backend device
*
* Disable DDR, setting into SDR mode (Single Data Rate).
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_ddr_disable(struct iio_backend *back)
{
return iio_backend_op_call(back, ddr_disable);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_ddr_disable, "IIO_BACKEND");
/**
* iio_backend_data_stream_enable - Enable data stream
* @back: Backend device
*
* Enable data stream over the bus interface.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_data_stream_enable(struct iio_backend *back)
{
return iio_backend_op_call(back, data_stream_enable);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_data_stream_enable, "IIO_BACKEND");
/**
* iio_backend_data_stream_disable - Disable data stream
* @back: Backend device
*
* Disable data stream over the bus interface.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_data_stream_disable(struct iio_backend *back)
{
return iio_backend_op_call(back, data_stream_disable);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_data_stream_disable, "IIO_BACKEND");
/**
* iio_backend_data_transfer_addr - Set data address.
* @back: Backend device
* @address: Data register address
*
* Some devices may need to inform the backend about an address
* where to read or write the data.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int iio_backend_data_transfer_addr(struct iio_backend *back, u32 address)
{
return iio_backend_op_call(back, data_transfer_addr, address);
}
EXPORT_SYMBOL_NS_GPL(iio_backend_data_transfer_addr, "IIO_BACKEND");
static struct iio_backend *__devm_iio_backend_fwnode_get(struct device *dev, const char *name,
struct fwnode_handle *fwnode)
{
struct fwnode_handle *fwnode_back;
struct iio_backend *back;
unsigned int index;
int ret;
if (name) {
ret = device_property_match_string(dev, "io-backend-names",
name);
if (ret < 0)
return ERR_PTR(ret);
index = ret;
} else {
index = 0;
}
fwnode_back = fwnode_find_reference(fwnode, "io-backends", index);
if (IS_ERR(fwnode_back))
return dev_err_cast_probe(dev, fwnode_back,
"Cannot get Firmware reference\n");
guard(mutex)(&iio_back_lock);
list_for_each_entry(back, &iio_back_list, entry) {
if (!device_match_fwnode(back->dev, fwnode_back))
continue;
fwnode_handle_put(fwnode_back);
ret = __devm_iio_backend_get(dev, back);
if (ret)
return ERR_PTR(ret);
if (name)
back->idx = index;
return back;
}
fwnode_handle_put(fwnode_back);
return ERR_PTR(-EPROBE_DEFER);
}
/**
* devm_iio_backend_get - Device managed backend device get
* @dev: Consumer device for the backend
* @name: Backend name
*
* Get's the backend associated with @dev.
*
* RETURNS:
* A backend pointer, negative error pointer otherwise.
*/
struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name)
{
return __devm_iio_backend_fwnode_get(dev, name, dev_fwnode(dev));
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_get, "IIO_BACKEND");
/**
* devm_iio_backend_fwnode_get - Device managed backend firmware node get
* @dev: Consumer device for the backend
* @name: Backend name
* @fwnode: Firmware node of the backend consumer
*
* Get's the backend associated with a firmware node.
*
* RETURNS:
* A backend pointer, negative error pointer otherwise.
*/
struct iio_backend *devm_iio_backend_fwnode_get(struct device *dev,
const char *name,
struct fwnode_handle *fwnode)
{
return __devm_iio_backend_fwnode_get(dev, name, fwnode);
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_fwnode_get, "IIO_BACKEND");
/**
* __devm_iio_backend_get_from_fwnode_lookup - Device managed fwnode backend device get
* @dev: Consumer device for the backend
* @fwnode: Firmware node of the backend device
*
* Search the backend list for a device matching @fwnode.
* This API should not be used and it's only present for preventing the first
* user of this framework to break it's DT ABI.
*
* RETURNS:
* A backend pointer, negative error pointer otherwise.
*/
struct iio_backend *
__devm_iio_backend_get_from_fwnode_lookup(struct device *dev,
struct fwnode_handle *fwnode)
{
struct iio_backend *back;
int ret;
guard(mutex)(&iio_back_lock);
list_for_each_entry(back, &iio_back_list, entry) {
if (!device_match_fwnode(back->dev, fwnode))
continue;
ret = __devm_iio_backend_get(dev, back);
if (ret)
return ERR_PTR(ret);
return back;
}
return ERR_PTR(-EPROBE_DEFER);
}
EXPORT_SYMBOL_NS_GPL(__devm_iio_backend_get_from_fwnode_lookup, "IIO_BACKEND");
/**
* iio_backend_get_priv - Get driver private data
* @back: Backend device
*/
void *iio_backend_get_priv(const struct iio_backend *back)
{
return back->priv;
}
EXPORT_SYMBOL_NS_GPL(iio_backend_get_priv, "IIO_BACKEND");
static void iio_backend_unregister(void *arg)
{
struct iio_backend *back = arg;
guard(mutex)(&iio_back_lock);
list_del(&back->entry);
}
/**
* devm_iio_backend_register - Device managed backend device register
* @dev: Backend device being registered
* @info: Backend info
* @priv: Device private data
*
* @info is mandatory. Not providing it results in -EINVAL.
*
* RETURNS:
* 0 on success, negative error number on failure.
*/
int devm_iio_backend_register(struct device *dev,
const struct iio_backend_info *info, void *priv)
{
struct iio_backend *back;
if (!info || !info->ops)
return dev_err_probe(dev, -EINVAL, "No backend ops given\n");
/*
* Through device_links, we guarantee that a frontend device cannot be
* bound/exist if the backend driver is not around. Hence, we can bind
* the backend object lifetime with the device being passed since
* removing it will tear the frontend/consumer down.
*/
back = devm_kzalloc(dev, sizeof(*back), GFP_KERNEL);
if (!back)
return -ENOMEM;
back->ops = info->ops;
back->name = info->name;
back->owner = dev->driver->owner;
back->dev = dev;
back->priv = priv;
scoped_guard(mutex, &iio_back_lock)
list_add(&back->entry, &iio_back_list);
return devm_add_action_or_reset(dev, iio_backend_unregister, back);
}
EXPORT_SYMBOL_NS_GPL(devm_iio_backend_register, "IIO_BACKEND");
MODULE_AUTHOR("Nuno Sa <nuno.sa@analog.com>");
MODULE_DESCRIPTION("Framework to handle complex IIO aggregate devices");
MODULE_LICENSE("GPL");
|