summaryrefslogtreecommitdiff
path: root/include/linux/spi/spi.h
blob: bc6bb325d1bf7c03db223c568b891e5d33dc93ca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
/*
 * Copyright (C) 2005 David Brownell
 *
 * 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.
 */

#ifndef __LINUX_SPI_H
#define __LINUX_SPI_H

#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/completion.h>
#include <linux/scatterlist.h>

struct dma_chan;
struct property_entry;
struct spi_controller;
struct spi_transfer;
struct spi_flash_read_message;

/*
 * INTERFACES between SPI master-side drivers and SPI slave protocol handlers,
 * and SPI infrastructure.
 */
extern struct bus_type spi_bus_type;

/**
 * struct spi_statistics - statistics for spi transfers
 * @lock:          lock protecting this structure
 *
 * @messages:      number of spi-messages handled
 * @transfers:     number of spi_transfers handled
 * @errors:        number of errors during spi_transfer
 * @timedout:      number of timeouts during spi_transfer
 *
 * @spi_sync:      number of times spi_sync is used
 * @spi_sync_immediate:
 *                 number of times spi_sync is executed immediately
 *                 in calling context without queuing and scheduling
 * @spi_async:     number of times spi_async is used
 *
 * @bytes:         number of bytes transferred to/from device
 * @bytes_tx:      number of bytes sent to device
 * @bytes_rx:      number of bytes received from device
 *
 * @transfer_bytes_histo:
 *                 transfer bytes histogramm
 *
 * @transfers_split_maxsize:
 *                 number of transfers that have been split because of
 *                 maxsize limit
 */
struct spi_statistics {
	spinlock_t		lock; /* lock for the whole structure */

	unsigned long		messages;
	unsigned long		transfers;
	unsigned long		errors;
	unsigned long		timedout;

	unsigned long		spi_sync;
	unsigned long		spi_sync_immediate;
	unsigned long		spi_async;

	unsigned long long	bytes;
	unsigned long long	bytes_rx;
	unsigned long long	bytes_tx;

#define SPI_STATISTICS_HISTO_SIZE 17
	unsigned long transfer_bytes_histo[SPI_STATISTICS_HISTO_SIZE];

	unsigned long transfers_split_maxsize;
};

void spi_statistics_add_transfer_stats(struct spi_statistics *stats,
				       struct spi_transfer *xfer,
				       struct spi_controller *ctlr);

#define SPI_STATISTICS_ADD_TO_FIELD(stats, field, count)	\
	do {							\
		unsigned long flags;				\
		spin_lock_irqsave(&(stats)->lock, flags);	\
		(stats)->field += count;			\
		spin_unlock_irqrestore(&(stats)->lock, flags);	\
	} while (0)

#define SPI_STATISTICS_INCREMENT_FIELD(stats, field)	\
	SPI_STATISTICS_ADD_TO_FIELD(stats, field, 1)

/**
 * struct spi_device - Controller side proxy for an SPI slave device
 * @dev: Driver model representation of the device.
 * @controller: SPI controller used with the device.
 * @master: Copy of controller, for backwards compatibility.
 * @max_speed_hz: Maximum clock rate to be used with this chip
 *	(on this board); may be changed by the device's driver.
 *	The spi_transfer.speed_hz can override this for each transfer.
 * @chip_select: Chipselect, distinguishing chips handled by @controller.
 * @mode: The spi mode defines how data is clocked out and in.
 *	This may be changed by the device's driver.
 *	The "active low" default for chipselect mode can be overridden
 *	(by specifying SPI_CS_HIGH) as can the "MSB first" default for
 *	each word in a transfer (by specifying SPI_LSB_FIRST).
 * @bits_per_word: Data transfers involve one or more words; word sizes
 *	like eight or 12 bits are common.  In-memory wordsizes are
 *	powers of two bytes (e.g. 20 bit samples use 32 bits).
 *	This may be changed by the device's driver, or left at the
 *	default (0) indicating protocol words are eight bit bytes.
 *	The spi_transfer.bits_per_word can override this for each transfer.
 * @irq: Negative, or the number passed to request_irq() to receive
 *	interrupts from this device.
 * @controller_state: Controller's runtime state
 * @controller_data: Board-specific definitions for controller, such as
 *	FIFO initialization parameters; from board_info.controller_data
 * @modalias: Name of the driver to use with this device, or an alias
 *	for that name.  This appears in the sysfs "modalias" attribute
 *	for driver coldplugging, and in uevents used for hotplugging
 * @cs_gpio: gpio number of the chipselect line (optional, -ENOENT when
 *	not using a GPIO line)
 *
 * @statistics: statistics for the spi_device
 *
 * A @spi_device is used to interchange data between an SPI slave
 * (usually a discrete chip) and CPU memory.
 *
 * In @dev, the platform_data is used to hold information about this
 * device that's meaningful to the device's protocol driver, but not
 * to its controller.  One example might be an identifier for a chip
 * variant with slightly different functionality; another might be
 * information about how this particular board wires the chip's pins.
 */
struct spi_device {
	struct device		dev;
	struct spi_controller	*controller;
	struct spi_controller	*master;	/* compatibility layer */
	u32			max_speed_hz;
	u8			chip_select;
	u8			bits_per_word;
	u16			mode;
#define	SPI_CPHA	0x01			/* clock phase */
#define	SPI_CPOL	0x02			/* clock polarity */
#define	SPI_MODE_0	(0|0)			/* (original MicroWire) */
#define	SPI_MODE_1	(0|SPI_CPHA)
#define	SPI_MODE_2	(SPI_CPOL|0)
#define	SPI_MODE_3	(SPI_CPOL|SPI_CPHA)
#define	SPI_CS_HIGH	0x04			/* chipselect active high? */
#define	SPI_LSB_FIRST	0x08			/* per-word bits-on-wire */
#define	SPI_3WIRE	0x10			/* SI/SO signals shared */
#define	SPI_LOOP	0x20			/* loopback mode */
#define	SPI_NO_CS	0x40			/* 1 dev/bus, no chipselect */
#define	SPI_READY	0x80			/* slave pulls low to pause */
#define	SPI_TX_DUAL	0x100			/* transmit with 2 wires */
#define	SPI_TX_QUAD	0x200			/* transmit with 4 wires */
#define	SPI_RX_DUAL	0x400			/* receive with 2 wires */
#define	SPI_RX_QUAD	0x800			/* receive with 4 wires */
	int			irq;
	void			*controller_state;
	void			*controller_data;
	char			modalias[SPI_NAME_SIZE];
	int			cs_gpio;	/* chip select gpio */

	/* the statistics */
	struct spi_statistics	statistics;

	/*
	 * likely need more hooks for more protocol options affecting how
	 * the controller talks to each chip, like:
	 *  - memory packing (12 bit samples into low bits, others zeroed)
	 *  - priority
	 *  - drop chipselect after each word
	 *  - chipselect delays
	 *  - ...
	 */
};

static inline struct spi_device *to_spi_device(struct device *dev)
{
	return dev ? container_of(dev, struct spi_device, dev) : NULL;
}

/* most drivers won't need to care about device refcounting */
static inline struct spi_device *spi_dev_get(struct spi_device *spi)
{
	return (spi && get_device(&spi->dev)) ? spi : NULL;
}

static inline void spi_dev_put(struct spi_device *spi)
{
	if (spi)
		put_device(&spi->dev);
}

/* ctldata is for the bus_controller driver's runtime state */
static inline void *spi_get_ctldata(struct spi_device *spi)
{
	return spi->controller_state;
}

static inline void spi_set_ctldata(struct spi_device *spi, void *state)
{
	spi->controller_state = state;
}

/* device driver data */

static inline void spi_set_drvdata(struct spi_device *spi, void *data)
{
	dev_set_drvdata(&spi->dev, data);
}

static inline void *spi_get_drvdata(struct spi_device *spi)
{
	return dev_get_drvdata(&spi->dev);
}

struct spi_message;
struct spi_transfer;

/**
 * struct spi_driver - Host side "protocol" driver
 * @id_table: List of SPI devices supported by this driver
 * @probe: Binds this driver to the spi device.  Drivers can verify
 *	that the device is actually present, and may need to configure
 *	characteristics (such as bits_per_word) which weren't needed for
 *	the initial configuration done during system setup.
 * @remove: Unbinds this driver from the spi device
 * @shutdown: Standard shutdown callback used during system state
 *	transitions such as powerdown/halt and kexec
 * @driver: SPI device drivers should initialize the name and owner
 *	field of this structure.
 *
 * This represents the kind of device driver that uses SPI messages to
 * interact with the hardware at the other end of a SPI link.  It's called
 * a "protocol" driver because it works through messages rather than talking
 * directly to SPI hardware (which is what the underlying SPI controller
 * driver does to pass those messages).  These protocols are defined in the
 * specification for the device(s) supported by the driver.
 *
 * As a rule, those device protocols represent the lowest level interface
 * supported by a driver, and it will support upper level interfaces too.
 * Examples of such upper levels include frameworks like MTD, networking,
 * MMC, RTC, filesystem character device nodes, and hardware monitoring.
 */
struct spi_driver {
	const struct spi_device_id *id_table;
	int			(*probe)(struct spi_device *spi);
	int			(*remove)(struct spi_device *spi);
	void			(*shutdown)(struct spi_device *spi);
	struct device_driver	driver;
};

static inline struct spi_driver *to_spi_driver(struct device_driver *drv)
{
	return drv ? container_of(drv, struct spi_driver, driver) : NULL;
}

extern int __spi_register_driver(struct module *owner, struct spi_driver *sdrv);

/**
 * spi_unregister_driver - reverse effect of spi_register_driver
 * @sdrv: the driver to unregister
 * Context: can sleep
 */
static inline void spi_unregister_driver(struct spi_driver *sdrv)
{
	if (sdrv)
		driver_unregister(&sdrv->driver);
}

/* use a define to avoid include chaining to get THIS_MODULE */
#define spi_register_driver(driver) \
	__spi_register_driver(THIS_MODULE, driver)

/**
 * module_spi_driver() - Helper macro for registering a SPI driver
 * @__spi_driver: spi_driver struct
 *
 * Helper macro for SPI drivers which do not do anything special in module
 * init/exit. This eliminates a lot of boilerplate. Each module may only
 * use this macro once, and calling it replaces module_init() and module_exit()
 */
#define module_spi_driver(__spi_driver) \
	module_driver(__spi_driver, spi_register_driver, \
			spi_unregister_driver)

/**
 * struct spi_controller - interface to SPI master or slave controller
 * @dev: device interface to this driver
 * @list: link with the global spi_controller list
 * @bus_num: board-specific (and often SOC-specific) identifier for a
 *	given SPI controller.
 * @num_chipselect: chipselects are used to distinguish individual
 *	SPI slaves, and are numbered from zero to num_chipselects.
 *	each slave has a chipselect signal, but it's common that not
 *	every chipselect is connected to a slave.
 * @dma_alignment: SPI controller constraint on DMA buffers alignment.
 * @mode_bits: flags understood by this controller driver
 * @bits_per_word_mask: A mask indicating which values of bits_per_word are
 *	supported by the driver. Bit n indicates that a bits_per_word n+1 is
 *	supported. If set, the SPI core will reject any transfer with an
 *	unsupported bits_per_word. If not set, this value is simply ignored,
 *	and it's up to the individual driver to perform any validation.
 * @min_speed_hz: Lowest supported transfer speed
 * @max_speed_hz: Highest supported transfer speed
 * @flags: other constraints relevant to this driver
 * @slave: indicates that this is an SPI slave controller
 * @max_transfer_size: function that returns the max transfer size for
 *	a &spi_device; may be %NULL, so the default %SIZE_MAX will be used.
 * @max_message_size: function that returns the max message size for
 *	a &spi_device; may be %NULL, so the default %SIZE_MAX will be used.
 * @io_mutex: mutex for physical bus access
 * @bus_lock_spinlock: spinlock for SPI bus locking
 * @bus_lock_mutex: mutex for exclusion of multiple callers
 * @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
 * @setup: updates the device mode and clocking records used by a
 *	device's SPI controller; protocol code may call this.  This
 *	must fail if an unrecognized or unsupported mode is requested.
 *	It's always safe to call this unless transfers are pending on
 *	the device whose settings are being modified.
 * @transfer: adds a message to the controller's transfer queue.
 * @cleanup: frees controller-specific state
 * @can_dma: determine whether this controller supports DMA
 * @queued: whether this controller is providing an internal message queue
 * @kworker: thread struct for message pump
 * @kworker_task: pointer to task for message pump kworker thread
 * @pump_messages: work struct for scheduling work to the message pump
 * @queue_lock: spinlock to syncronise access to message queue
 * @queue: message queue
 * @idling: the device is entering idle state
 * @cur_msg: the currently in-flight message
 * @cur_msg_prepared: spi_prepare_message was called for the currently
 *                    in-flight message
 * @cur_msg_mapped: message has been mapped for DMA
 * @xfer_completion: used by core transfer_one_message()
 * @busy: message pump is busy
 * @running: message pump is running
 * @rt: whether this queue is set to run as a realtime task
 * @auto_runtime_pm: the core should ensure a runtime PM reference is held
 *                   while the hardware is prepared, using the parent
 *                   device for the spidev
 * @max_dma_len: Maximum length of a DMA transfer for the device.
 * @prepare_transfer_hardware: a message will soon arrive from the queue
 *	so the subsystem requests the driver to prepare the transfer hardware
 *	by issuing this call
 * @transfer_one_message: the subsystem calls the driver to transfer a single
 *	message while queuing transfers that arrive in the meantime. When the
 *	driver is finished with this message, it must call
 *	spi_finalize_current_message() so the subsystem can issue the next
 *	message
 * @unprepare_transfer_hardware: there are currently no more messages on the
 *	queue so the subsystem notifies the driver that it may relax the
 *	hardware by issuing this call
 * @set_cs: set the logic level of the chip select line.  May be called
 *          from interrupt context.
 * @prepare_message: set up the controller to transfer a single message,
 *                   for example doing DMA mapping.  Called from threaded
 *                   context.
 * @transfer_one: transfer a single spi_transfer.
 *                  - return 0 if the transfer is finished,
 *                  - return 1 if the transfer is still in progress. When
 *                    the driver is finished with this transfer it must
 *                    call spi_finalize_current_transfer() so the subsystem
 *                    can issue the next transfer. Note: transfer_one and
 *                    transfer_one_message are mutually exclusive; when both
 *                    are set, the generic subsystem does not call your
 *                    transfer_one callback.
 * @handle_err: the subsystem calls the driver to handle an error that occurs
 *		in the generic implementation of transfer_one_message().
 * @unprepare_message: undo any work done by prepare_message().
 * @slave_abort: abort the ongoing transfer request on an SPI slave controller
 * @spi_flash_read: to support spi-controller hardwares that provide
 *                  accelerated interface to read from flash devices.
 * @spi_flash_can_dma: analogous to can_dma() interface, but for
 *		       controllers implementing spi_flash_read.
 * @flash_read_supported: spi device supports flash read
 * @cs_gpios: Array of GPIOs to use as chip select lines; one per CS
 *	number. Any individual value may be -ENOENT for CS lines that
 *	are not GPIOs (driven by the SPI controller itself).
 * @statistics: statistics for the spi_controller
 * @dma_tx: DMA transmit channel
 * @dma_rx: DMA receive channel
 * @dummy_rx: dummy receive buffer for full-duplex devices
 * @dummy_tx: dummy transmit buffer for full-duplex devices
 * @fw_translate_cs: If the boot firmware uses different numbering scheme
 *	what Linux expects, this optional hook can be used to translate
 *	between the two.
 *
 * Each SPI controller can communicate with one or more @spi_device
 * children.  These make a small bus, sharing MOSI, MISO and SCK signals
 * but not chip select signals.  Each device may be configured to use a
 * different clock rate, since those shared signals are ignored unless
 * the chip is selected.
 *
 * The driver for an SPI controller manages access to those devices through
 * a queue of spi_message transactions, copying data between CPU memory and
 * an SPI slave device.  For each such message it queues, it calls the
 * message's completion function when the transaction completes.
 */
struct spi_controller {
	struct device	dev;

	struct list_head list;

	/* other than negative (== assign one dynamically), bus_num is fully
	 * board-specific.  usually that simplifies to being SOC-specific.
	 * example:  one SOC has three SPI controllers, numbered 0..2,
	 * and one board's schematics might show it using SPI-2.  software
	 * would normally use bus_num=2 for that controller.
	 */
	s16			bus_num;

	/* chipselects will be integral to many controllers; some others
	 * might use board-specific GPIOs.
	 */
	u16			num_chipselect;

	/* some SPI controllers pose alignment requirements on DMAable
	 * buffers; let protocol drivers know about these requirements.
	 */
	u16			dma_alignment;

	/* spi_device.mode flags understood by this controller driver */
	u16			mode_bits;

	/* bitmask of supported bits_per_word for transfers */
	u32			bits_per_word_mask;
#define SPI_BPW_MASK(bits) BIT((bits) - 1)
#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))

	/* limits on transfer speed */
	u32			min_speed_hz;
	u32			max_speed_hz;

	/* other constraints relevant to this driver */
	u16			flags;
#define SPI_CONTROLLER_HALF_DUPLEX	BIT(0)	/* can't do full duplex */
#define SPI_CONTROLLER_NO_RX		BIT(1)	/* can't do buffer read */
#define SPI_CONTROLLER_NO_TX		BIT(2)	/* can't do buffer write */
#define SPI_CONTROLLER_MUST_RX		BIT(3)	/* requires rx */
#define SPI_CONTROLLER_MUST_TX		BIT(4)	/* requires tx */

#define SPI_MASTER_GPIO_SS		BIT(5)	/* GPIO CS must select slave */

	/* flag indicating this is an SPI slave controller */
	bool			slave;

	/*
	 * on some hardware transfer / message size may be constrained
	 * the limit may depend on device transfer settings
	 */
	size_t (*max_transfer_size)(struct spi_device *spi);
	size_t (*max_message_size)(struct spi_device *spi);

	/* I/O mutex */
	struct mutex		io_mutex;

	/* lock and mutex for SPI bus locking */
	spinlock_t		bus_lock_spinlock;
	struct mutex		bus_lock_mutex;

	/* flag indicating that the SPI bus is locked for exclusive use */
	bool			bus_lock_flag;

	/* Setup mode and clock, etc (spi driver may call many times).
	 *
	 * IMPORTANT:  this may be called when transfers to another
	 * device are active.  DO NOT UPDATE SHARED REGISTERS in ways
	 * which could break those transfers.
	 */
	int			(*setup)(struct spi_device *spi);

	/* bidirectional bulk transfers
	 *
	 * + The transfer() method may not sleep; its main role is
	 *   just to add the message to the queue.
	 * + For now there's no remove-from-queue operation, or
	 *   any other request management
	 * + To a given spi_device, message queueing is pure fifo
	 *
	 * + The controller's main job is to process its message queue,
	 *   selecting a chip (for masters), then transferring data
	 * + If there are multiple spi_device children, the i/o queue
	 *   arbitration algorithm is unspecified (round robin, fifo,
	 *   priority, reservations, preemption, etc)
	 *
	 * + Chipselect stays active during the entire message
	 *   (unless modified by spi_transfer.cs_change != 0).
	 * + The message transfers use clock and SPI mode parameters
	 *   previously established by setup() for this device
	 */
	int			(*transfer)(struct spi_device *spi,
						struct spi_message *mesg);

	/* called on release() to free memory provided by spi_controller */
	void			(*cleanup)(struct spi_device *spi);

	/*
	 * Used to enable core support for DMA handling, if can_dma()
	 * exists and returns true then the transfer will be mapped
	 * prior to transfer_one() being called.  The driver should
	 * not modify or store xfer and dma_tx and dma_rx must be set
	 * while the device is prepared.
	 */
	bool			(*can_dma)(struct spi_controller *ctlr,
					   struct spi_device *spi,
					   struct spi_transfer *xfer);

	/*
	 * These hooks are for drivers that want to use the generic
	 * controller transfer queueing mechanism. If these are used, the
	 * transfer() function above must NOT be specified by the driver.
	 * Over time we expect SPI drivers to be phased over to this API.
	 */
	bool				queued;
	struct kthread_worker		kworker;
	struct task_struct		*kworker_task;
	struct kthread_work		pump_messages;
	spinlock_t			queue_lock;
	struct list_head		queue;
	struct spi_message		*cur_msg;
	bool				idling;
	bool				busy;
	bool				running;
	bool				rt;
	bool				auto_runtime_pm;
	bool                            cur_msg_prepared;
	bool				cur_msg_mapped;
	struct completion               xfer_completion;
	size_t				max_dma_len;

	int (*prepare_transfer_hardware)(struct spi_controller *ctlr);
	int (*transfer_one_message)(struct spi_controller *ctlr,
				    struct spi_message *mesg);
	int (*unprepare_transfer_hardware)(struct spi_controller *ctlr);
	int (*prepare_message)(struct spi_controller *ctlr,
			       struct spi_message *message);
	int (*unprepare_message)(struct spi_controller *ctlr,
				 struct spi_message *message);
	int (*slave_abort)(struct spi_controller *ctlr);
	int (*spi_flash_read)(struct  spi_device *spi,
			      struct spi_flash_read_message *msg);
	bool (*spi_flash_can_dma)(struct spi_device *spi,
				  struct spi_flash_read_message *msg);
	bool (*flash_read_supported)(struct spi_device *spi);

	/*
	 * These hooks are for drivers that use a generic implementation
	 * of transfer_one_message() provied by the core.
	 */
	void (*set_cs)(struct spi_device *spi, bool enable);
	int (*transfer_one)(struct spi_controller *ctlr, struct spi_device *spi,
			    struct spi_transfer *transfer);
	void (*handle_err)(struct spi_controller *ctlr,
			   struct spi_message *message);

	/* gpio chip select */
	int			*cs_gpios;

	/* statistics */
	struct spi_statistics	statistics;

	/* DMA channels for use with core dmaengine helpers */
	struct dma_chan		*dma_tx;
	struct dma_chan		*dma_rx;

	/* dummy data for full duplex devices */
	void			*dummy_rx;
	void			*dummy_tx;

	int (*fw_translate_cs)(struct spi_controller *ctlr, unsigned cs);
};

static inline void *spi_controller_get_devdata(struct spi_controller *ctlr)
{
	return dev_get_drvdata(&ctlr->dev);
}

static inline void spi_controller_set_devdata(struct spi_controller *ctlr,
					      void *data)
{
	dev_set_drvdata(&ctlr->dev, data);
}

static inline struct spi_controller *spi_controller_get(struct spi_controller *ctlr)
{
	if (!ctlr || !get_device(&ctlr->dev))
		return NULL;
	return ctlr;
}

static inline void spi_controller_put(struct spi_controller *ctlr)
{
	if (ctlr)
		put_device(&ctlr->dev);
}

static inline bool spi_controller_is_slave(struct spi_controller *ctlr)
{
	return IS_ENABLED(CONFIG_SPI_SLAVE) && ctlr->slave;
}

/* PM calls that need to be issued by the driver */
extern int spi_controller_suspend(struct spi_controller *ctlr);
extern int spi_controller_resume(struct spi_controller *ctlr);

/* Calls the driver make to interact with the message queue */
extern struct spi_message *spi_get_next_queued_message(struct spi_controller *ctlr);
extern void spi_finalize_current_message(struct spi_controller *ctlr);
extern void spi_finalize_current_transfer(struct spi_controller *ctlr);

/* the spi driver core manages memory for the spi_controller classdev */
extern struct spi_controller *__spi_alloc_controller(struct device *host,
						unsigned int size, bool slave);

static inline struct spi_controller *spi_alloc_master(struct device *host,
						      unsigned int size)
{
	return __spi_alloc_controller(host, size, false);
}

static inline struct spi_controller *spi_alloc_slave(struct device *host,
						     unsigned int size)
{
	if (!IS_ENABLED(CONFIG_SPI_SLAVE))
		return NULL;

	return __spi_alloc_controller(host, size, true);
}

extern int spi_register_controller(struct spi_controller *ctlr);
extern int devm_spi_register_controller(struct device *dev,
					struct spi_controller *ctlr);
extern void spi_unregister_controller(struct spi_controller *ctlr);

extern struct spi_controller *spi_busnum_to_master(u16 busnum);

/*
 * SPI resource management while processing a SPI message
 */

typedef void (*spi_res_release_t)(struct spi_controller *ctlr,
				  struct spi_message *msg,
				  void *res);

/**
 * struct spi_res - spi resource management structure
 * @entry:   list entry
 * @release: release code called prior to freeing this resource
 * @data:    extra data allocated for the specific use-case
 *
 * this is based on ideas from devres, but focused on life-cycle
 * management during spi_message processing
 */
struct spi_res {
	struct list_head        entry;
	spi_res_release_t       release;
	unsigned long long      data[]; /* guarantee ull alignment */
};

extern void *spi_res_alloc(struct spi_device *spi,
			   spi_res_release_t release,
			   size_t size, gfp_t gfp);
extern void spi_res_add(struct spi_message *message, void *res);
extern void spi_res_free(void *res);

extern void spi_res_release(struct spi_controller *ctlr,
			    struct spi_message *message);

/*---------------------------------------------------------------------------*/

/*
 * I/O INTERFACE between SPI controller and protocol drivers
 *
 * Protocol drivers use a queue of spi_messages, each transferring data
 * between the controller and memory buffers.
 *
 * The spi_messages themselves consist of a series of read+write transfer
 * segments.  Those segments always read the same number of bits as they
 * write; but one or the other is easily ignored by passing a null buffer
 * pointer.  (This is unlike most types of I/O API, because SPI hardware
 * is full duplex.)
 *
 * NOTE:  Allocation of spi_transfer and spi_message memory is entirely
 * up to the protocol driver, which guarantees the integrity of both (as
 * well as the data buffers) for as long as the message is queued.
 */

/**
 * struct spi_transfer - a read/write buffer pair
 * @tx_buf: data to be written (dma-safe memory), or NULL
 * @rx_buf: data to be read (dma-safe memory), or NULL
 * @tx_dma: DMA address of tx_buf, if @spi_message.is_dma_mapped
 * @rx_dma: DMA address of rx_buf, if @spi_message.is_dma_mapped
 * @tx_nbits: number of bits used for writing. If 0 the default
 *      (SPI_NBITS_SINGLE) is used.
 * @rx_nbits: number of bits used for reading. If 0 the default
 *      (SPI_NBITS_SINGLE) is used.
 * @len: size of rx and tx buffers (in bytes)
 * @speed_hz: Select a speed other than the device default for this
 *      transfer. If 0 the default (from @spi_device) is used.
 * @bits_per_word: select a bits_per_word other than the device default
 *      for this transfer. If 0 the default (from @spi_device) is used.
 * @cs_change: affects chipselect after this transfer completes
 * @delay_usecs: microseconds to delay after this transfer before
 *	(optionally) changing the chipselect status, then starting
 *	the next transfer or completing this @spi_message.
 * @transfer_list: transfers are sequenced through @spi_message.transfers
 * @tx_sg: Scatterlist for transmit, currently not for client use
 * @rx_sg: Scatterlist for receive, currently not for client use
 *
 * SPI transfers always write the same number of bytes as they read.
 * Protocol drivers should always provide @rx_buf and/or @tx_buf.
 * In some cases, they may also want to provide DMA addresses for
 * the data being transferred; that may reduce overhead, when the
 * underlying driver uses dma.
 *
 * If the transmit buffer is null, zeroes will be shifted out
 * while filling @rx_buf.  If the receive buffer is null, the data
 * shifted in will be discarded.  Only "len" bytes shift out (or in).
 * It's an error to try to shift out a partial word.  (For example, by
 * shifting out three bytes with word size of sixteen or twenty bits;
 * the former uses two bytes per word, the latter uses four bytes.)
 *
 * In-memory data values are always in native CPU byte order, translated
 * from the wire byte order (big-endian except with SPI_LSB_FIRST).  So
 * for example when bits_per_word is sixteen, buffers are 2N bytes long
 * (@len = 2N) and hold N sixteen bit words in CPU byte order.
 *
 * When the word size of the SPI transfer is not a power-of-two multiple
 * of eight bits, those in-memory words include extra bits.  In-memory
 * words are always seen by protocol drivers as right-justified, so the
 * undefined (rx) or unused (tx) bits are always the most significant bits.
 *
 * All SPI transfers start with the relevant chipselect active.  Normally
 * it stays selected until after the last transfer in a message.  Drivers
 * can affect the chipselect signal using cs_change.
 *
 * (i) If the transfer isn't the last one in the message, this flag is
 * used to make the chipselect briefly go inactive in the middle of the
 * message.  Toggling chipselect in this way may be needed to terminate
 * a chip command, letting a single spi_message perform all of group of
 * chip transactions together.
 *
 * (ii) When the transfer is the last one in the message, the chip may
 * stay selected until the next transfer.  On multi-device SPI busses
 * with nothing blocking messages going to other devices, this is just
 * a performance hint; starting a message to another device deselects
 * this one.  But in other cases, this can be used to ensure correctness.
 * Some devices need protocol transactions to be built from a series of
 * spi_message submissions, where the content of one message is determined
 * by the results of previous messages and where the whole transaction
 * ends when the chipselect goes intactive.
 *
 * When SPI can transfer in 1x,2x or 4x. It can get this transfer information
 * from device through @tx_nbits and @rx_nbits. In Bi-direction, these
 * two should both be set. User can set transfer mode with SPI_NBITS_SINGLE(1x)
 * SPI_NBITS_DUAL(2x) and SPI_NBITS_QUAD(4x) to support these three transfer.
 *
 * The code that submits an spi_message (and its spi_transfers)
 * to the lower layers is responsible for managing its memory.
 * Zero-initialize every field you don't set up explicitly, to
 * insulate against future API updates.  After you submit a message
 * and its transfers, ignore them until its completion callback.
 */
struct spi_transfer {
	/* it's ok if tx_buf == rx_buf (right?)
	 * for MicroWire, one buffer must be null
	 * buffers must work with dma_*map_single() calls, unless
	 *   spi_message.is_dma_mapped reports a pre-existing mapping
	 */
	const void	*tx_buf;
	void		*rx_buf;
	unsigned	len;

	dma_addr_t	tx_dma;
	dma_addr_t	rx_dma;
	struct sg_table tx_sg;
	struct sg_table rx_sg;

	unsigned	cs_change:1;
	unsigned	tx_nbits:3;
	unsigned	rx_nbits:3;
#define	SPI_NBITS_SINGLE	0x01 /* 1bit transfer */
#define	SPI_NBITS_DUAL		0x02 /* 2bits transfer */
#define	SPI_NBITS_QUAD		0x04 /* 4bits transfer */
	u8		bits_per_word;
	u16		delay_usecs;
	u32		speed_hz;

	struct list_head transfer_list;
};

/**
 * struct spi_message - one multi-segment SPI transaction
 * @transfers: list of transfer segments in this transaction
 * @spi: SPI device to which the transaction is queued
 * @is_dma_mapped: if true, the caller provided both dma and cpu virtual
 *	addresses for each transfer buffer
 * @complete: called to report transaction completions
 * @context: the argument to complete() when it's called
 * @frame_length: the total number of bytes in the message
 * @actual_length: the total number of bytes that were transferred in all
 *	successful segments
 * @status: zero for success, else negative errno
 * @queue: for use by whichever driver currently owns the message
 * @state: for use by whichever driver currently owns the message
 * @resources: for resource management when the spi message is processed
 *
 * A @spi_message is used to execute an atomic sequence of data transfers,
 * each represented by a struct spi_transfer.  The sequence is "atomic"
 * in the sense that no other spi_message may use that SPI bus until that
 * sequence completes.  On some systems, many such sequences can execute as
 * as single programmed DMA transfer.  On all systems, these messages are
 * queued, and might complete after transactions to other devices.  Messages
 * sent to a given spi_device are always executed in FIFO order.
 *
 * The code that submits an spi_message (and its spi_transfers)
 * to the lower layers is responsible for managing its memory.
 * Zero-initialize every field you don't set up explicitly, to
 * insulate against future API updates.  After you submit a message
 * and its transfers, ignore them until its completion callback.
 */
struct spi_message {
	struct list_head	transfers;

	struct spi_device	*spi;

	unsigned		is_dma_mapped:1;

	/* REVISIT:  we might want a flag affecting the behavior of the
	 * last transfer ... allowing things like "read 16 bit length L"
	 * immediately followed by "read L bytes".  Basically imposing
	 * a specific message scheduling algorithm.
	 *
	 * Some controller drivers (message-at-a-time queue processing)
	 * could provide that as their default scheduling algorithm.  But
	 * others (with multi-message pipelines) could need a flag to
	 * tell them about such special cases.
	 */

	/* completion is reported through a callback */
	void			(*complete)(void *context);
	void			*context;
	unsigned		frame_length;
	unsigned		actual_length;
	int			status;

	/* for optional use by whatever driver currently owns the
	 * spi_message ...  between calls to spi_async and then later
	 * complete(), that's the spi_controller controller driver.
	 */
	struct list_head	queue;
	void			*state;

	/* list of spi_res reources when the spi message is processed */
	struct list_head        resources;
};

static inline void spi_message_init_no_memset(struct spi_message *m)
{
	INIT_LIST_HEAD(&m->transfers);
	INIT_LIST_HEAD(&m->resources);
}

static inline void spi_message_init(struct spi_message *m)
{
	memset(m, 0, sizeof *m);
	spi_message_init_no_memset(m);
}

static inline void
spi_message_add_tail(struct spi_transfer *t, struct spi_message *m)
{
	list_add_tail(&t->transfer_list, &m->transfers);
}

static inline void
spi_transfer_del(struct spi_transfer *t)
{
	list_del(&t->transfer_list);
}

/**
 * spi_message_init_with_transfers - Initialize spi_message and append transfers
 * @m: spi_message to be initialized
 * @xfers: An array of spi transfers
 * @num_xfers: Number of items in the xfer array
 *
 * This function initializes the given spi_message and adds each spi_transfer in
 * the given array to the message.
 */
static inline void
spi_message_init_with_transfers(struct spi_message *m,
struct spi_transfer *xfers, unsigned int num_xfers)
{
	unsigned int i;

	spi_message_init(m);
	for (i = 0; i < num_xfers; ++i)
		spi_message_add_tail(&xfers[i], m);
}

/* It's fine to embed message and transaction structures in other data
 * structures so long as you don't free them while they're in use.
 */

static inline struct spi_message *spi_message_alloc(unsigned ntrans, gfp_t flags)
{
	struct spi_message *m;

	m = kzalloc(sizeof(struct spi_message)
			+ ntrans * sizeof(struct spi_transfer),
			flags);
	if (m) {
		unsigned i;
		struct spi_transfer *t = (struct spi_transfer *)(m + 1);

		spi_message_init_no_memset(m);
		for (i = 0; i < ntrans; i++, t++)
			spi_message_add_tail(t, m);
	}
	return m;
}

static inline void spi_message_free(struct spi_message *m)
{
	kfree(m);
}

extern int spi_setup(struct spi_device *spi);
extern int spi_async(struct spi_device *spi, struct spi_message *message);
extern int spi_async_locked(struct spi_device *spi,
			    struct spi_message *message);
extern int spi_slave_abort(struct spi_device *spi);

static inline size_t
spi_max_message_size(struct spi_device *spi)
{
	struct spi_controller *ctlr = spi->controller;

	if (!ctlr->max_message_size)
		return SIZE_MAX;
	return ctlr->max_message_size(spi);
}

static inline size_t
spi_max_transfer_size(struct spi_device *spi)
{
	struct spi_controller *ctlr = spi->controller;
	size_t tr_max = SIZE_MAX;
	size_t msg_max = spi_max_message_size(spi);

	if (ctlr->max_transfer_size)
		tr_max = ctlr->max_transfer_size(spi);

	/* transfer size limit must not be greater than messsage size limit */
	return min(tr_max, msg_max);
}

/*---------------------------------------------------------------------------*/

/* SPI transfer replacement methods which make use of spi_res */

struct spi_replaced_transfers;
typedef void (*spi_replaced_release_t)(struct spi_controller *ctlr,
				       struct spi_message *msg,
				       struct spi_replaced_transfers *res);
/**
 * struct spi_replaced_transfers - structure describing the spi_transfer
 *                                 replacements that have occurred
 *                                 so that they can get reverted
 * @release:            some extra release code to get executed prior to
 *                      relasing this structure
 * @extradata:          pointer to some extra data if requested or NULL
 * @replaced_transfers: transfers that have been replaced and which need
 *                      to get restored
 * @replaced_after:     the transfer after which the @replaced_transfers
 *                      are to get re-inserted
 * @inserted:           number of transfers inserted
 * @inserted_transfers: array of spi_transfers of array-size @inserted,
 *                      that have been replacing replaced_transfers
 *
 * note: that @extradata will point to @inserted_transfers[@inserted]
 * if some extra allocation is requested, so alignment will be the same
 * as for spi_transfers
 */
struct spi_replaced_transfers {
	spi_replaced_release_t release;
	void *extradata;
	struct list_head replaced_transfers;
	struct list_head *replaced_after;
	size_t inserted;
	struct spi_transfer inserted_transfers[];
};

extern struct spi_replaced_transfers *spi_replace_transfers(
	struct spi_message *msg,
	struct spi_transfer *xfer_first,
	size_t remove,
	size_t insert,
	spi_replaced_release_t release,
	size_t extradatasize,
	gfp_t gfp);

/*---------------------------------------------------------------------------*/

/* SPI transfer transformation methods */

extern int spi_split_transfers_maxsize(struct spi_controller *ctlr,
				       struct spi_message *msg,
				       size_t maxsize,
				       gfp_t gfp);

/*---------------------------------------------------------------------------*/

/* All these synchronous SPI transfer routines are utilities layered
 * over the core async transfer primitive.  Here, "synchronous" means
 * they will sleep uninterruptibly until the async transfer completes.
 */

extern int spi_sync(struct spi_device *spi, struct spi_message *message);
extern int spi_sync_locked(struct spi_device *spi, struct spi_message *message);
extern int spi_bus_lock(struct spi_controller *ctlr);
extern int spi_bus_unlock(struct spi_controller *ctlr);

/**
 * spi_sync_transfer - synchronous SPI data transfer
 * @spi: device with which data will be exchanged
 * @xfers: An array of spi_transfers
 * @num_xfers: Number of items in the xfer array
 * Context: can sleep
 *
 * Does a synchronous SPI data transfer of the given spi_transfer array.
 *
 * For more specific semantics see spi_sync().
 *
 * Return: Return: zero on success, else a negative error code.
 */
static inline int
spi_sync_transfer(struct spi_device *spi, struct spi_transfer *xfers,
	unsigned int num_xfers)
{
	struct spi_message msg;

	spi_message_init_with_transfers(&msg, xfers, num_xfers);

	return spi_sync(spi, &msg);
}

/**
 * spi_write - SPI synchronous write
 * @spi: device to which data will be written
 * @buf: data buffer
 * @len: data buffer size
 * Context: can sleep
 *
 * This function writes the buffer @buf.
 * Callable only from contexts that can sleep.
 *
 * Return: zero on success, else a negative error code.
 */
static inline int
spi_write(struct spi_device *spi, const void *buf, size_t len)
{
	struct spi_transfer	t = {
			.tx_buf		= buf,
			.len		= len,
		};

	return spi_sync_transfer(spi, &t, 1);
}

/**
 * spi_read - SPI synchronous read
 * @spi: device from which data will be read
 * @buf: data buffer
 * @len: data buffer size
 * Context: can sleep
 *
 * This function reads the buffer @buf.
 * Callable only from contexts that can sleep.
 *
 * Return: zero on success, else a negative error code.
 */
static inline int
spi_read(struct spi_device *spi, void *buf, size_t len)
{
	struct spi_transfer	t = {
			.rx_buf		= buf,
			.len		= len,
		};

	return spi_sync_transfer(spi, &t, 1);
}

/* this copies txbuf and rxbuf data; for small transfers only! */
extern int spi_write_then_read(struct spi_device *spi,
		const void *txbuf, unsigned n_tx,
		void *rxbuf, unsigned n_rx);

/**
 * spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read
 * @spi: device with which data will be exchanged
 * @cmd: command to be written before data is read back
 * Context: can sleep
 *
 * Callable only from contexts that can sleep.
 *
 * Return: the (unsigned) eight bit number returned by the
 * device, or else a negative error code.
 */
static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd)
{
	ssize_t			status;
	u8			result;

	status = spi_write_then_read(spi, &cmd, 1, &result, 1);

	/* return negative errno or unsigned value */
	return (status < 0) ? status : result;
}

/**
 * spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read
 * @spi: device with which data will be exchanged
 * @cmd: command to be written before data is read back
 * Context: can sleep
 *
 * The number is returned in wire-order, which is at least sometimes
 * big-endian.
 *
 * Callable only from contexts that can sleep.
 *
 * Return: the (unsigned) sixteen bit number returned by the
 * device, or else a negative error code.
 */
static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd)
{
	ssize_t			status;
	u16			result;

	status = spi_write_then_read(spi, &cmd, 1, &result, 2);

	/* return negative errno or unsigned value */
	return (status < 0) ? status : result;
}

/**
 * spi_w8r16be - SPI synchronous 8 bit write followed by 16 bit big-endian read
 * @spi: device with which data will be exchanged
 * @cmd: command to be written before data is read back
 * Context: can sleep
 *
 * This function is similar to spi_w8r16, with the exception that it will
 * convert the read 16 bit data word from big-endian to native endianness.
 *
 * Callable only from contexts that can sleep.
 *
 * Return: the (unsigned) sixteen bit number returned by the device in cpu
 * endianness, or else a negative error code.
 */
static inline ssize_t spi_w8r16be(struct spi_device *spi, u8 cmd)

{
	ssize_t status;
	__be16 result;

	status = spi_write_then_read(spi, &cmd, 1, &result, 2);
	if (status < 0)
		return status;

	return be16_to_cpu(result);
}

/**
 * struct spi_flash_read_message - flash specific information for
 * spi-masters that provide accelerated flash read interfaces
 * @buf: buffer to read data
 * @from: offset within the flash from where data is to be read
 * @len: length of data to be read
 * @retlen: actual length of data read
 * @read_opcode: read_opcode to be used to communicate with flash
 * @addr_width: number of address bytes
 * @dummy_bytes: number of dummy bytes
 * @opcode_nbits: number of lines to send opcode
 * @addr_nbits: number of lines to send address
 * @data_nbits: number of lines for data
 * @rx_sg: Scatterlist for receive data read from flash
 * @cur_msg_mapped: message has been mapped for DMA
 */
struct spi_flash_read_message {
	void *buf;
	loff_t from;
	size_t len;
	size_t retlen;
	u8 read_opcode;
	u8 addr_width;
	u8 dummy_bytes;
	u8 opcode_nbits;
	u8 addr_nbits;
	u8 data_nbits;
	struct sg_table rx_sg;
	bool cur_msg_mapped;
};

/* SPI core interface for flash read support */
static inline bool spi_flash_read_supported(struct spi_device *spi)
{
	return spi->controller->spi_flash_read &&
	       (!spi->controller->flash_read_supported ||
	       spi->controller->flash_read_supported(spi));
}

int spi_flash_read(struct spi_device *spi,
		   struct spi_flash_read_message *msg);

/*---------------------------------------------------------------------------*/

/*
 * INTERFACE between board init code and SPI infrastructure.
 *
 * No SPI driver ever sees these SPI device table segments, but
 * it's how the SPI core (or adapters that get hotplugged) grows
 * the driver model tree.
 *
 * As a rule, SPI devices can't be probed.  Instead, board init code
 * provides a table listing the devices which are present, with enough
 * information to bind and set up the device's driver.  There's basic
 * support for nonstatic configurations too; enough to handle adding
 * parport adapters, or microcontrollers acting as USB-to-SPI bridges.
 */

/**
 * struct spi_board_info - board-specific template for a SPI device
 * @modalias: Initializes spi_device.modalias; identifies the driver.
 * @platform_data: Initializes spi_device.platform_data; the particular
 *	data stored there is driver-specific.
 * @properties: Additional device properties for the device.
 * @controller_data: Initializes spi_device.controller_data; some
 *	controllers need hints about hardware setup, e.g. for DMA.
 * @irq: Initializes spi_device.irq; depends on how the board is wired.
 * @max_speed_hz: Initializes spi_device.max_speed_hz; based on limits
 *	from the chip datasheet and board-specific signal quality issues.
 * @bus_num: Identifies which spi_controller parents the spi_device; unused
 *	by spi_new_device(), and otherwise depends on board wiring.
 * @chip_select: Initializes spi_device.chip_select; depends on how
 *	the board is wired.
 * @mode: Initializes spi_device.mode; based on the chip datasheet, board
 *	wiring (some devices support both 3WIRE and standard modes), and
 *	possibly presence of an inverter in the chipselect path.
 *
 * When adding new SPI devices to the device tree, these structures serve
 * as a partial device template.  They hold information which can't always
 * be determined by drivers.  Information that probe() can establish (such
 * as the default transfer wordsize) is not included here.
 *
 * These structures are used in two places.  Their primary role is to
 * be stored in tables of board-specific device descriptors, which are
 * declared early in board initialization and then used (much later) to
 * populate a controller's device tree after the that controller's driver
 * initializes.  A secondary (and atypical) role is as a parameter to
 * spi_new_device() call, which happens after those controller drivers
 * are active in some dynamic board configuration models.
 */
struct spi_board_info {
	/* the device name and module name are coupled, like platform_bus;
	 * "modalias" is normally the driver name.
	 *
	 * platform_data goes to spi_device.dev.platform_data,
	 * controller_data goes to spi_device.controller_data,
	 * device properties are copied and attached to spi_device,
	 * irq is copied too
	 */
	char		modalias[SPI_NAME_SIZE];
	const void	*platform_data;
	const struct property_entry *properties;
	void		*controller_data;
	int		irq;

	/* slower signaling on noisy or low voltage boards */
	u32		max_speed_hz;


	/* bus_num is board specific and matches the bus_num of some
	 * spi_controller that will probably be registered later.
	 *
	 * chip_select reflects how this chip is wired to that master;
	 * it's less than num_chipselect.
	 */
	u16		bus_num;
	u16		chip_select;

	/* mode becomes spi_device.mode, and is essential for chips
	 * where the default of SPI_CS_HIGH = 0 is wrong.
	 */
	u16		mode;

	/* ... may need additional spi_device chip config data here.
	 * avoid stuff protocol drivers can set; but include stuff
	 * needed to behave without being bound to a driver:
	 *  - quirks like clock rate mattering when not selected
	 */
};

#ifdef	CONFIG_SPI
extern int
spi_register_board_info(struct spi_board_info const *info, unsigned n);
#else
/* board init code may ignore whether SPI is configured or not */
static inline int
spi_register_board_info(struct spi_board_info const *info, unsigned n)
	{ return 0; }
#endif


/* If you're hotplugging an adapter with devices (parport, usb, etc)
 * use spi_new_device() to describe each device.  You can also call
 * spi_unregister_device() to start making that device vanish, but
 * normally that would be handled by spi_unregister_controller().
 *
 * You can also use spi_alloc_device() and spi_add_device() to use a two
 * stage registration sequence for each spi_device.  This gives the caller
 * some more control over the spi_device structure before it is registered,
 * but requires that caller to initialize fields that would otherwise
 * be defined using the board info.
 */
extern struct spi_device *
spi_alloc_device(struct spi_controller *ctlr);

extern int
spi_add_device(struct spi_device *spi);

extern struct spi_device *
spi_new_device(struct spi_controller *, struct spi_board_info *);

extern void spi_unregister_device(struct spi_device *spi);

extern const struct spi_device_id *
spi_get_device_id(const struct spi_device *sdev);

static inline bool
spi_transfer_is_last(struct spi_controller *ctlr, struct spi_transfer *xfer)
{
	return list_is_last(&xfer->transfer_list, &ctlr->cur_msg->transfers);
}


/* Compatibility layer */
#define spi_master			spi_controller

#define SPI_MASTER_HALF_DUPLEX		SPI_CONTROLLER_HALF_DUPLEX
#define SPI_MASTER_NO_RX		SPI_CONTROLLER_NO_RX
#define SPI_MASTER_NO_TX		SPI_CONTROLLER_NO_TX
#define SPI_MASTER_MUST_RX		SPI_CONTROLLER_MUST_RX
#define SPI_MASTER_MUST_TX		SPI_CONTROLLER_MUST_TX

#define spi_master_get_devdata(_ctlr)	spi_controller_get_devdata(_ctlr)
#define spi_master_set_devdata(_ctlr, _data)	\
	spi_controller_set_devdata(_ctlr, _data)
#define spi_master_get(_ctlr)		spi_controller_get(_ctlr)
#define spi_master_put(_ctlr)		spi_controller_put(_ctlr)
#define spi_master_suspend(_ctlr)	spi_controller_suspend(_ctlr)
#define spi_master_resume(_ctlr)	spi_controller_resume(_ctlr)

#define spi_register_master(_ctlr)	spi_register_controller(_ctlr)
#define devm_spi_register_master(_dev, _ctlr) \
	devm_spi_register_controller(_dev, _ctlr)
#define spi_unregister_master(_ctlr)	spi_unregister_controller(_ctlr)

#endif /* __LINUX_SPI_H */