summaryrefslogtreecommitdiffstats
path: root/drivers/gpio/gpiolib-of.c
blob: 0ad288ab6262ddb57cd32fabadcde88e1c8cd6b9 (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
// SPDX-License-Identifier: GPL-2.0+
/*
 * OF helpers for the GPIO API
 *
 * Copyright (c) 2007-2008  MontaVista Software, Inc.
 *
 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_gpio.h>
#include <linux/pinctrl/pinctrl.h>
#include <linux/slab.h>
#include <linux/gpio/machine.h>

#include "gpiolib.h"
#include "gpiolib-of.h"

/**
 * of_gpio_spi_cs_get_count() - special GPIO counting for SPI
 * @dev:    Consuming device
 * @con_id: Function within the GPIO consumer
 *
 * Some elder GPIO controllers need special quirks. Currently we handle
 * the Freescale and PPC GPIO controller with bindings that doesn't use the
 * established "cs-gpios" for chip selects but instead rely on
 * "gpios" for the chip select lines. If we detect this, we redirect
 * the counting of "cs-gpios" to count "gpios" transparent to the
 * driver.
 */
static int of_gpio_spi_cs_get_count(struct device *dev, const char *con_id)
{
	struct device_node *np = dev->of_node;

	if (!IS_ENABLED(CONFIG_SPI_MASTER))
		return 0;
	if (!con_id || strcmp(con_id, "cs"))
		return 0;
	if (!of_device_is_compatible(np, "fsl,spi") &&
	    !of_device_is_compatible(np, "aeroflexgaisler,spictrl") &&
	    !of_device_is_compatible(np, "ibm,ppc4xx-spi"))
		return 0;
	return of_gpio_named_count(np, "gpios");
}

/*
 * This is used by external users of of_gpio_count() from <linux/of_gpio.h>
 *
 * FIXME: get rid of those external users by converting them to GPIO
 * descriptors and let them all use gpiod_count()
 */
int of_gpio_get_count(struct device *dev, const char *con_id)
{
	int ret;
	char propname[32];
	unsigned int i;

	ret = of_gpio_spi_cs_get_count(dev, con_id);
	if (ret > 0)
		return ret;

	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
		if (con_id)
			snprintf(propname, sizeof(propname), "%s-%s",
				 con_id, gpio_suffixes[i]);
		else
			snprintf(propname, sizeof(propname), "%s",
				 gpio_suffixes[i]);

		ret = of_gpio_named_count(dev->of_node, propname);
		if (ret > 0)
			break;
	}
	return ret ? ret : -ENOENT;
}

static int of_gpiochip_match_node_and_xlate(struct gpio_chip *chip, void *data)
{
	struct of_phandle_args *gpiospec = data;

	return chip->gpiodev->dev.of_node == gpiospec->np &&
				chip->of_xlate &&
				chip->of_xlate(chip, gpiospec, NULL) >= 0;
}

static struct gpio_chip *of_find_gpiochip_by_xlate(
					struct of_phandle_args *gpiospec)
{
	return gpiochip_find(gpiospec, of_gpiochip_match_node_and_xlate);
}

static struct gpio_desc *of_xlate_and_get_gpiod_flags(struct gpio_chip *chip,
					struct of_phandle_args *gpiospec,
					enum of_gpio_flags *flags)
{
	int ret;

	if (chip->of_gpio_n_cells != gpiospec->args_count)
		return ERR_PTR(-EINVAL);

	ret = chip->of_xlate(chip, gpiospec, flags);
	if (ret < 0)
		return ERR_PTR(ret);

	return gpiochip_get_desc(chip, ret);
}

/**
 * of_gpio_need_valid_mask() - figure out if the OF GPIO driver needs
 * to set the .valid_mask
 * @gc: the target gpio_chip
 *
 * Return: true if the valid mask needs to be set
 */
bool of_gpio_need_valid_mask(const struct gpio_chip *gc)
{
	int size;
	const struct device_node *np = gc->of_node;

	size = of_property_count_u32_elems(np,  "gpio-reserved-ranges");
	if (size > 0 && size % 2 == 0)
		return true;
	return false;
}

static void of_gpio_flags_quirks(const struct device_node *np,
				 const char *propname,
				 enum of_gpio_flags *flags,
				 int index)
{
	/*
	 * Some GPIO fixed regulator quirks.
	 * Note that active low is the default.
	 */
	if (IS_ENABLED(CONFIG_REGULATOR) &&
	    (of_device_is_compatible(np, "regulator-fixed") ||
	     of_device_is_compatible(np, "reg-fixed-voltage") ||
	     (!(strcmp(propname, "enable-gpio") &&
		strcmp(propname, "enable-gpios")) &&
	      of_device_is_compatible(np, "regulator-gpio")))) {
		bool active_low = !of_property_read_bool(np,
							 "enable-active-high");
		/*
		 * The regulator GPIO handles are specified such that the
		 * presence or absence of "enable-active-high" solely controls
		 * the polarity of the GPIO line. Any phandle flags must
		 * be actively ignored.
		 */
		if ((*flags & OF_GPIO_ACTIVE_LOW) && !active_low) {
			pr_warn("%s GPIO handle specifies active low - ignored\n",
				of_node_full_name(np));
			*flags &= ~OF_GPIO_ACTIVE_LOW;
		}
		if (active_low)
			*flags |= OF_GPIO_ACTIVE_LOW;
	}
	/*
	 * Legacy open drain handling for fixed voltage regulators.
	 */
	if (IS_ENABLED(CONFIG_REGULATOR) &&
	    of_device_is_compatible(np, "reg-fixed-voltage") &&
	    of_property_read_bool(np, "gpio-open-drain")) {
		*flags |= (OF_GPIO_SINGLE_ENDED | OF_GPIO_OPEN_DRAIN);
		pr_info("%s uses legacy open drain flag - update the DTS if you can\n",
			of_node_full_name(np));
	}

	/*
	 * Legacy handling of SPI active high chip select. If we have a
	 * property named "cs-gpios" we need to inspect the child node
	 * to determine if the flags should have inverted semantics.
	 */
	if (IS_ENABLED(CONFIG_SPI_MASTER) && !strcmp(propname, "cs-gpios") &&
	    of_property_read_bool(np, "cs-gpios")) {
		struct device_node *child;
		u32 cs;
		int ret;

		for_each_child_of_node(np, child) {
			ret = of_property_read_u32(child, "reg", &cs);
			if (ret)
				continue;
			if (cs == index) {
				/*
				 * SPI children have active low chip selects
				 * by default. This can be specified negatively
				 * by just omitting "spi-cs-high" in the
				 * device node, or actively by tagging on
				 * GPIO_ACTIVE_LOW as flag in the device
				 * tree. If the line is simultaneously
				 * tagged as active low in the device tree
				 * and has the "spi-cs-high" set, we get a
				 * conflict and the "spi-cs-high" flag will
				 * take precedence.
				 */
				if (of_property_read_bool(child, "spi-cs-high")) {
					if (*flags & OF_GPIO_ACTIVE_LOW) {
						pr_warn("%s GPIO handle specifies active low - ignored\n",
							of_node_full_name(child));
						*flags &= ~OF_GPIO_ACTIVE_LOW;
					}
				} else {
					if (!(*flags & OF_GPIO_ACTIVE_LOW))
						pr_info("%s enforce active low on chipselect handle\n",
							of_node_full_name(child));
					*flags |= OF_GPIO_ACTIVE_LOW;
				}
				of_node_put(child);
				break;
			}
		}
	}

	/* Legacy handling of stmmac's active-low PHY reset line */
	if (IS_ENABLED(CONFIG_STMMAC_ETH) &&
	    !strcmp(propname, "snps,reset-gpio") &&
	    of_property_read_bool(np, "snps,reset-active-low"))
		*flags |= OF_GPIO_ACTIVE_LOW;
}

/**
 * of_get_named_gpiod_flags() - Get a GPIO descriptor and flags for GPIO API
 * @np:		device node to get GPIO from
 * @propname:	property name containing gpio specifier(s)
 * @index:	index of the GPIO
 * @flags:	a flags pointer to fill in
 *
 * Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
 * value on the error condition. If @flags is not NULL the function also fills
 * in flags for the GPIO.
 */
static struct gpio_desc *of_get_named_gpiod_flags(const struct device_node *np,
		     const char *propname, int index, enum of_gpio_flags *flags)
{
	struct of_phandle_args gpiospec;
	struct gpio_chip *chip;
	struct gpio_desc *desc;
	int ret;

	ret = of_parse_phandle_with_args_map(np, propname, "gpio", index,
					     &gpiospec);
	if (ret) {
		pr_debug("%s: can't parse '%s' property of node '%pOF[%d]'\n",
			__func__, propname, np, index);
		return ERR_PTR(ret);
	}

	chip = of_find_gpiochip_by_xlate(&gpiospec);
	if (!chip) {
		desc = ERR_PTR(-EPROBE_DEFER);
		goto out;
	}

	desc = of_xlate_and_get_gpiod_flags(chip, &gpiospec, flags);
	if (IS_ERR(desc))
		goto out;

	if (flags)
		of_gpio_flags_quirks(np, propname, flags, index);

	pr_debug("%s: parsed '%s' property of node '%pOF[%d]' - status (%d)\n",
		 __func__, propname, np, index,
		 PTR_ERR_OR_ZERO(desc));

out:
	of_node_put(gpiospec.np);

	return desc;
}

int of_get_named_gpio_flags(const struct device_node *np, const char *list_name,
			    int index, enum of_gpio_flags *flags)
{
	struct gpio_desc *desc;

	desc = of_get_named_gpiod_flags(np, list_name, index, flags);

	if (IS_ERR(desc))
		return PTR_ERR(desc);
	else
		return desc_to_gpio(desc);
}
EXPORT_SYMBOL_GPL(of_get_named_gpio_flags);

/**
 * gpiod_get_from_of_node() - obtain a GPIO from an OF node
 * @node:	handle of the OF node
 * @propname:	name of the DT property representing the GPIO
 * @index:	index of the GPIO to obtain for the consumer
 * @dflags:	GPIO initialization flags
 * @label:	label to attach to the requested GPIO
 *
 * Returns:
 * On successful request the GPIO pin is configured in accordance with
 * provided @dflags.
 *
 * In case of error an ERR_PTR() is returned.
 */
struct gpio_desc *gpiod_get_from_of_node(const struct device_node *node,
					 const char *propname, int index,
					 enum gpiod_flags dflags,
					 const char *label)
{
	unsigned long lflags = GPIO_LOOKUP_FLAGS_DEFAULT;
	struct gpio_desc *desc;
	enum of_gpio_flags flags;
	bool active_low = false;
	bool single_ended = false;
	bool open_drain = false;
	bool transitory = false;
	int ret;

	desc = of_get_named_gpiod_flags(node, propname,
					index, &flags);

	if (!desc || IS_ERR(desc)) {
		return desc;
	}

	active_low = flags & OF_GPIO_ACTIVE_LOW;
	single_ended = flags & OF_GPIO_SINGLE_ENDED;
	open_drain = flags & OF_GPIO_OPEN_DRAIN;
	transitory = flags & OF_GPIO_TRANSITORY;

	ret = gpiod_request(desc, label);
	if (ret == -EBUSY && (dflags & GPIOD_FLAGS_BIT_NONEXCLUSIVE))
		return desc;
	if (ret)
		return ERR_PTR(ret);

	if (active_low)
		lflags |= GPIO_ACTIVE_LOW;

	if (single_ended) {
		if (open_drain)
			lflags |= GPIO_OPEN_DRAIN;
		else
			lflags |= GPIO_OPEN_SOURCE;
	}

	if (transitory)
		lflags |= GPIO_TRANSITORY;

	if (flags & OF_GPIO_PULL_UP)
		lflags |= GPIO_PULL_UP;

	if (flags & OF_GPIO_PULL_DOWN)
		lflags |= GPIO_PULL_DOWN;

	ret = gpiod_configure_flags(desc, propname, lflags, dflags);
	if (ret < 0) {
		gpiod_put(desc);
		return ERR_PTR(ret);
	}

	return desc;
}
EXPORT_SYMBOL_GPL(gpiod_get_from_of_node);

/*
 * The SPI GPIO bindings happened before we managed to establish that GPIO
 * properties should be named "foo-gpios" so we have this special kludge for
 * them.
 */
static struct gpio_desc *of_find_spi_gpio(struct device *dev, const char *con_id,
					  enum of_gpio_flags *of_flags)
{
	char prop_name[32]; /* 32 is max size of property name */
	const struct device_node *np = dev->of_node;
	struct gpio_desc *desc;

	/*
	 * Hopefully the compiler stubs the rest of the function if this
	 * is false.
	 */
	if (!IS_ENABLED(CONFIG_SPI_MASTER))
		return ERR_PTR(-ENOENT);

	/* Allow this specifically for "spi-gpio" devices */
	if (!of_device_is_compatible(np, "spi-gpio") || !con_id)
		return ERR_PTR(-ENOENT);

	/* Will be "gpio-sck", "gpio-mosi" or "gpio-miso" */
	snprintf(prop_name, sizeof(prop_name), "%s-%s", "gpio", con_id);

	desc = of_get_named_gpiod_flags(np, prop_name, 0, of_flags);
	return desc;
}

/*
 * The old Freescale bindings use simply "gpios" as name for the chip select
 * lines rather than "cs-gpios" like all other SPI hardware. Account for this
 * with a special quirk.
 */
static struct gpio_desc *of_find_spi_cs_gpio(struct device *dev,
					     const char *con_id,
					     unsigned int idx,
					     unsigned long *flags)
{
	const struct device_node *np = dev->of_node;

	if (!IS_ENABLED(CONFIG_SPI_MASTER))
		return ERR_PTR(-ENOENT);

	/* Allow this specifically for Freescale and PPC devices */
	if (!of_device_is_compatible(np, "fsl,spi") &&
	    !of_device_is_compatible(np, "aeroflexgaisler,spictrl") &&
	    !of_device_is_compatible(np, "ibm,ppc4xx-spi"))
		return ERR_PTR(-ENOENT);
	/* Allow only if asking for "cs-gpios" */
	if (!con_id || strcmp(con_id, "cs"))
		return ERR_PTR(-ENOENT);

	/*
	 * While all other SPI controllers use "cs-gpios" the Freescale
	 * uses just "gpios" so translate to that when "cs-gpios" is
	 * requested.
	 */
	return of_find_gpio(dev, NULL, idx, flags);
}

/*
 * Some regulator bindings happened before we managed to establish that GPIO
 * properties should be named "foo-gpios" so we have this special kludge for
 * them.
 */
static struct gpio_desc *of_find_regulator_gpio(struct device *dev, const char *con_id,
						enum of_gpio_flags *of_flags)
{
	/* These are the connection IDs we accept as legacy GPIO phandles */
	const char *whitelist[] = {
		"wlf,ldoena", /* Arizona */
		"wlf,ldo1ena", /* WM8994 */
		"wlf,ldo2ena", /* WM8994 */
	};
	const struct device_node *np = dev->of_node;
	struct gpio_desc *desc;
	int i;

	if (!IS_ENABLED(CONFIG_REGULATOR))
		return ERR_PTR(-ENOENT);

	if (!con_id)
		return ERR_PTR(-ENOENT);

	i = match_string(whitelist, ARRAY_SIZE(whitelist), con_id);
	if (i < 0)
		return ERR_PTR(-ENOENT);

	desc = of_get_named_gpiod_flags(np, con_id, 0, of_flags);
	return desc;
}

static struct gpio_desc *of_find_arizona_gpio(struct device *dev,
					      const char *con_id,
					      enum of_gpio_flags *of_flags)
{
	if (!IS_ENABLED(CONFIG_MFD_ARIZONA))
		return ERR_PTR(-ENOENT);

	if (!con_id || strcmp(con_id, "wlf,reset"))
		return ERR_PTR(-ENOENT);

	return of_get_named_gpiod_flags(dev->of_node, con_id, 0, of_flags);
}

static struct gpio_desc *of_find_usb_gpio(struct device *dev,
					  const char *con_id,
					  enum of_gpio_flags *of_flags)
{
	/*
	 * Currently this USB quirk is only for the Fairchild FUSB302 host which is using
	 * an undocumented DT GPIO line named "fcs,int_n" without the compulsory "-gpios"
	 * suffix.
	 */
	if (!IS_ENABLED(CONFIG_TYPEC_FUSB302))
		return ERR_PTR(-ENOENT);

	if (!con_id || strcmp(con_id, "fcs,int_n"))
		return ERR_PTR(-ENOENT);

	return of_get_named_gpiod_flags(dev->of_node, con_id, 0, of_flags);
}

struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
			       unsigned int idx, unsigned long *flags)
{
	char prop_name[32]; /* 32 is max size of property name */
	enum of_gpio_flags of_flags;
	struct gpio_desc *desc;
	unsigned int i;

	/* Try GPIO property "foo-gpios" and "foo-gpio" */
	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
		if (con_id)
			snprintf(prop_name, sizeof(prop_name), "%s-%s", con_id,
				 gpio_suffixes[i]);
		else
			snprintf(prop_name, sizeof(prop_name), "%s",
				 gpio_suffixes[i]);

		desc = of_get_named_gpiod_flags(dev->of_node, prop_name, idx,
						&of_flags);

		if (!gpiod_not_found(desc))
			break;
	}

	if (gpiod_not_found(desc)) {
		/* Special handling for SPI GPIOs if used */
		desc = of_find_spi_gpio(dev, con_id, &of_flags);
	}

	if (gpiod_not_found(desc)) {
		/* This quirk looks up flags and all */
		desc = of_find_spi_cs_gpio(dev, con_id, idx, flags);
		if (!IS_ERR(desc))
			return desc;
	}

	if (gpiod_not_found(desc)) {
		/* Special handling for regulator GPIOs if used */
		desc = of_find_regulator_gpio(dev, con_id, &of_flags);
	}

	if (gpiod_not_found(desc))
		desc = of_find_arizona_gpio(dev, con_id, &of_flags);

	if (gpiod_not_found(desc))
		desc = of_find_usb_gpio(dev, con_id, &of_flags);

	if (IS_ERR(desc))
		return desc;

	if (of_flags & OF_GPIO_ACTIVE_LOW)
		*flags |= GPIO_ACTIVE_LOW;

	if (of_flags & OF_GPIO_SINGLE_ENDED) {
		if (of_flags & OF_GPIO_OPEN_DRAIN)
			*flags |= GPIO_OPEN_DRAIN;
		else
			*flags |= GPIO_OPEN_SOURCE;
	}

	if (of_flags & OF_GPIO_TRANSITORY)
		*flags |= GPIO_TRANSITORY;

	if (of_flags & OF_GPIO_PULL_UP)
		*flags |= GPIO_PULL_UP;
	if (of_flags & OF_GPIO_PULL_DOWN)
		*flags |= GPIO_PULL_DOWN;

	return desc;
}

/**
 * of_parse_own_gpio() - Get a GPIO hog descriptor, names and flags for GPIO API
 * @np:		device node to get GPIO from
 * @chip:	GPIO chip whose hog is parsed
 * @idx:	Index of the GPIO to parse
 * @name:	GPIO line name
 * @lflags:	bitmask of gpio_lookup_flags GPIO_* values - returned from
 *		of_find_gpio() or of_parse_own_gpio()
 * @dflags:	gpiod_flags - optional GPIO initialization flags
 *
 * Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
 * value on the error condition.
 */
static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
					   struct gpio_chip *chip,
					   unsigned int idx, const char **name,
					   unsigned long *lflags,
					   enum gpiod_flags *dflags)
{
	struct device_node *chip_np;
	enum of_gpio_flags xlate_flags;
	struct of_phandle_args gpiospec;
	struct gpio_desc *desc;
	unsigned int i;
	u32 tmp;
	int ret;

	chip_np = chip->of_node;
	if (!chip_np)
		return ERR_PTR(-EINVAL);

	xlate_flags = 0;
	*lflags = GPIO_LOOKUP_FLAGS_DEFAULT;
	*dflags = GPIOD_ASIS;

	ret = of_property_read_u32(chip_np, "#gpio-cells", &tmp);
	if (ret)
		return ERR_PTR(ret);

	gpiospec.np = chip_np;
	gpiospec.args_count = tmp;

	for (i = 0; i < tmp; i++) {
		ret = of_property_read_u32_index(np, "gpios", idx * tmp + i,
						 &gpiospec.args[i]);
		if (ret)
			return ERR_PTR(ret);
	}

	desc = of_xlate_and_get_gpiod_flags(chip, &gpiospec, &xlate_flags);
	if (IS_ERR(desc))
		return desc;

	if (xlate_flags & OF_GPIO_ACTIVE_LOW)
		*lflags |= GPIO_ACTIVE_LOW;
	if (xlate_flags & OF_GPIO_TRANSITORY)
		*lflags |= GPIO_TRANSITORY;
	if (xlate_flags & OF_GPIO_PULL_UP)
		*lflags |= GPIO_PULL_UP;
	if (xlate_flags & OF_GPIO_PULL_DOWN)
		*lflags |= GPIO_PULL_DOWN;

	if (of_property_read_bool(np, "input"))
		*dflags |= GPIOD_IN;
	else if (of_property_read_bool(np, "output-low"))
		*dflags |= GPIOD_OUT_LOW;
	else if (of_property_read_bool(np, "output-high"))
		*dflags |= GPIOD_OUT_HIGH;
	else {
		pr_warn("GPIO line %d (%pOFn): no hogging state specified, bailing out\n",
			desc_to_gpio(desc), np);
		return ERR_PTR(-EINVAL);
	}

	if (name && of_property_read_string(np, "line-name", name))
		*name = np->name;

	return desc;
}

/**
 * of_gpiochip_add_hog - Add all hogs in a hog device node
 * @chip:	gpio chip to act on
 * @hog:	device node describing the hogs
 *
 * Returns error if it fails otherwise 0 on success.
 */
static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
{
	enum gpiod_flags dflags;
	struct gpio_desc *desc;
	unsigned long lflags;
	const char *name;
	unsigned int i;
	int ret;

	for (i = 0;; i++) {
		desc = of_parse_own_gpio(hog, chip, i, &name, &lflags, &dflags);
		if (IS_ERR(desc))
			break;

		ret = gpiod_hog(desc, name, lflags, dflags);
		if (ret < 0)
			return ret;

#ifdef CONFIG_OF_DYNAMIC
		desc->hog = hog;
#endif
	}

	return 0;
}

/**
 * of_gpiochip_scan_gpios - Scan gpio-controller for gpio definitions
 * @chip:	gpio chip to act on
 *
 * This is only used by of_gpiochip_add to request/set GPIO initial
 * configuration.
 * It returns error if it fails otherwise 0 on success.
 */
static int of_gpiochip_scan_gpios(struct gpio_chip *chip)
{
	struct device_node *np;
	int ret;

	for_each_available_child_of_node(chip->of_node, np) {
		if (!of_property_read_bool(np, "gpio-hog"))
			continue;

		ret = of_gpiochip_add_hog(chip, np);
		if (ret < 0) {
			of_node_put(np);
			return ret;
		}

		of_node_set_flag(np, OF_POPULATED);
	}

	return 0;
}

#ifdef CONFIG_OF_DYNAMIC
/**
 * of_gpiochip_remove_hog - Remove all hogs in a hog device node
 * @chip:	gpio chip to act on
 * @hog:	device node describing the hogs
 */
static void of_gpiochip_remove_hog(struct gpio_chip *chip,
				   struct device_node *hog)
{
	struct gpio_desc *descs = chip->gpiodev->descs;
	unsigned int i;

	for (i = 0; i < chip->ngpio; i++) {
		if (test_bit(FLAG_IS_HOGGED, &descs[i].flags) &&
		    descs[i].hog == hog)
			gpiochip_free_own_desc(&descs[i]);
	}
}

static int of_gpiochip_match_node(struct gpio_chip *chip, void *data)
{
	return chip->gpiodev->dev.of_node == data;
}

static struct gpio_chip *of_find_gpiochip_by_node(struct device_node *np)
{
	return gpiochip_find(np, of_gpiochip_match_node);
}

static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
			  void *arg)
{
	struct of_reconfig_data *rd = arg;
	struct gpio_chip *chip;
	int ret;

	/*
	 * This only supports adding and removing complete gpio-hog nodes.
	 * Modifying an existing gpio-hog node is not supported (except for
	 * changing its "status" property, which is treated the same as
	 * addition/removal).
	 */
	switch (of_reconfig_get_state_change(action, arg)) {
	case OF_RECONFIG_CHANGE_ADD:
		if (!of_property_read_bool(rd->dn, "gpio-hog"))
			return NOTIFY_OK;	/* not for us */

		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED))
			return NOTIFY_OK;

		chip = of_find_gpiochip_by_node(rd->dn->parent);
		if (chip == NULL)
			return NOTIFY_OK;	/* not for us */

		ret = of_gpiochip_add_hog(chip, rd->dn);
		if (ret < 0) {
			pr_err("%s: failed to add hogs for %pOF\n", __func__,
			       rd->dn);
			of_node_clear_flag(rd->dn, OF_POPULATED);
			return notifier_from_errno(ret);
		}
		break;

	case OF_RECONFIG_CHANGE_REMOVE:
		if (!of_node_check_flag(rd->dn, OF_POPULATED))
			return NOTIFY_OK;	/* already depopulated */

		chip = of_find_gpiochip_by_node(rd->dn->parent);
		if (chip == NULL)
			return NOTIFY_OK;	/* not for us */

		of_gpiochip_remove_hog(chip, rd->dn);
		of_node_clear_flag(rd->dn, OF_POPULATED);
		break;
	}

	return NOTIFY_OK;
}

struct notifier_block gpio_of_notifier = {
	.notifier_call = of_gpio_notify,
};
#endif /* CONFIG_OF_DYNAMIC */

/**
 * of_gpio_simple_xlate - translate gpiospec to the GPIO number and flags
 * @gc:		pointer to the gpio_chip structure
 * @gpiospec:	GPIO specifier as found in the device tree
 * @flags:	a flags pointer to fill in
 *
 * This is simple translation function, suitable for the most 1:1 mapped
 * GPIO chips. This function performs only one sanity check: whether GPIO
 * is less than ngpios (that is specified in the gpio_chip).
 */
static int of_gpio_simple_xlate(struct gpio_chip *gc,
				const struct of_phandle_args *gpiospec,
				u32 *flags)
{
	/*
	 * We're discouraging gpio_cells < 2, since that way you'll have to
	 * write your own xlate function (that will have to retrieve the GPIO
	 * number and the flags from a single gpio cell -- this is possible,
	 * but not recommended).
	 */
	if (gc->of_gpio_n_cells < 2) {
		WARN_ON(1);
		return -EINVAL;
	}

	if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
		return -EINVAL;

	if (gpiospec->args[0] >= gc->ngpio)
		return -EINVAL;

	if (flags)
		*flags = gpiospec->args[1];

	return gpiospec->args[0];
}

/**
 * of_mm_gpiochip_add_data - Add memory mapped GPIO chip (bank)
 * @np:		device node of the GPIO chip
 * @mm_gc:	pointer to the of_mm_gpio_chip allocated structure
 * @data:	driver data to store in the struct gpio_chip
 *
 * To use this function you should allocate and fill mm_gc with:
 *
 * 1) In the gpio_chip structure:
 *    - all the callbacks
 *    - of_gpio_n_cells
 *    - of_xlate callback (optional)
 *
 * 3) In the of_mm_gpio_chip structure:
 *    - save_regs callback (optional)
 *
 * If succeeded, this function will map bank's memory and will
 * do all necessary work for you. Then you'll able to use .regs
 * to manage GPIOs from the callbacks.
 */
int of_mm_gpiochip_add_data(struct device_node *np,
			    struct of_mm_gpio_chip *mm_gc,
			    void *data)
{
	int ret = -ENOMEM;
	struct gpio_chip *gc = &mm_gc->gc;

	gc->label = kasprintf(GFP_KERNEL, "%pOF", np);
	if (!gc->label)
		goto err0;

	mm_gc->regs = of_iomap(np, 0);
	if (!mm_gc->regs)
		goto err1;

	gc->base = -1;

	if (mm_gc->save_regs)
		mm_gc->save_regs(mm_gc);

	mm_gc->gc.of_node = np;

	ret = gpiochip_add_data(gc, data);
	if (ret)
		goto err2;

	return 0;
err2:
	iounmap(mm_gc->regs);
err1:
	kfree(gc->label);
err0:
	pr_err("%pOF: GPIO chip registration failed with status %d\n", np, ret);
	return ret;
}
EXPORT_SYMBOL_GPL(of_mm_gpiochip_add_data);

/**
 * of_mm_gpiochip_remove - Remove memory mapped GPIO chip (bank)
 * @mm_gc:	pointer to the of_mm_gpio_chip allocated structure
 */
void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc)
{
	struct gpio_chip *gc = &mm_gc->gc;

	if (!mm_gc)
		return;

	gpiochip_remove(gc);
	iounmap(mm_gc->regs);
	kfree(gc->label);
}
EXPORT_SYMBOL_GPL(of_mm_gpiochip_remove);

static void of_gpiochip_init_valid_mask(struct gpio_chip *chip)
{
	int len, i;
	u32 start, count;
	struct device_node *np = chip->of_node;

	len = of_property_count_u32_elems(np,  "gpio-reserved-ranges");
	if (len < 0 || len % 2 != 0)
		return;

	for (i = 0; i < len; i += 2) {
		of_property_read_u32_index(np, "gpio-reserved-ranges",
					   i, &start);
		of_property_read_u32_index(np, "gpio-reserved-ranges",
					   i + 1, &count);
		if (start >= chip->ngpio || start + count >= chip->ngpio)
			continue;

		bitmap_clear(chip->valid_mask, start, count);
	}
};

#ifdef CONFIG_PINCTRL
static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
{
	struct device_node *np = chip->of_node;
	struct of_phandle_args pinspec;
	struct pinctrl_dev *pctldev;
	int index = 0, ret;
	const char *name;
	static const char group_names_propname[] = "gpio-ranges-group-names";
	struct property *group_names;

	if (!np)
		return 0;

	group_names = of_find_property(np, group_names_propname, NULL);

	for (;; index++) {
		ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3,
				index, &pinspec);
		if (ret)
			break;

		pctldev = of_pinctrl_get(pinspec.np);
		of_node_put(pinspec.np);
		if (!pctldev)
			return -EPROBE_DEFER;

		if (pinspec.args[2]) {
			if (group_names) {
				of_property_read_string_index(np,
						group_names_propname,
						index, &name);
				if (strlen(name)) {
					pr_err("%pOF: Group name of numeric GPIO ranges must be the empty string.\n",
						np);
					break;
				}
			}
			/* npins != 0: linear range */
			ret = gpiochip_add_pin_range(chip,
					pinctrl_dev_get_devname(pctldev),
					pinspec.args[0],
					pinspec.args[1],
					pinspec.args[2]);
			if (ret)
				return ret;
		} else {
			/* npins == 0: special range */
			if (pinspec.args[1]) {
				pr_err("%pOF: Illegal gpio-range format.\n",
					np);
				break;
			}

			if (!group_names) {
				pr_err("%pOF: GPIO group range requested but no %s property.\n",
					np, group_names_propname);
				break;
			}

			ret = of_property_read_string_index(np,
						group_names_propname,
						index, &name);
			if (ret)
				break;

			if (!strlen(name)) {
				pr_err("%pOF: Group name of GPIO group range cannot be the empty string.\n",
				np);
				break;
			}

			ret = gpiochip_add_pingroup_range(chip, pctldev,
						pinspec.args[0], name);
			if (ret)
				return ret;
		}
	}

	return 0;
}

#else
static int of_gpiochip_add_pin_range(struct gpio_chip *chip) { return 0; }
#endif

int of_gpiochip_add(struct gpio_chip *chip)
{
	int ret;

	if (!chip->of_node)
		return 0;

	if (!chip->of_xlate) {
		chip->of_gpio_n_cells = 2;
		chip->of_xlate = of_gpio_simple_xlate;
	}

	if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)
		return -EINVAL;

	of_gpiochip_init_valid_mask(chip);

	ret = of_gpiochip_add_pin_range(chip);
	if (ret)
		return ret;

	of_node_get(chip->of_node);

	ret = of_gpiochip_scan_gpios(chip);
	if (ret)
		of_node_put(chip->of_node);

	return ret;
}

void of_gpiochip_remove(struct gpio_chip *chip)
{
	of_node_put(chip->of_node);
}

void of_gpio_dev_init(struct gpio_chip *gc, struct gpio_device *gdev)
{
	/* Set default OF node to parent's one if present */
	if (gc->parent)
		gdev->dev.of_node = gc->parent->of_node;

	/* If the gpiochip has an assigned OF node this takes precedence */
	if (gc->of_node)
		gdev->dev.of_node = gc->of_node;
	else
		gc->of_node = gdev->dev.of_node;
}