summaryrefslogtreecommitdiff
path: root/drivers/spi/spi.c
blob: 32e4603d5fc89573ef634708383e821bcf8f189c (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
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
/*
 * SPI init/core code
 *
 * Copyright (C) 2005 David Brownell
 * Copyright (C) 2008 Secret Lab Technologies Ltd.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/cache.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/mutex.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/slab.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/of_gpio.h>
#include <linux/pm_runtime.h>
#include <linux/export.h>
#include <linux/sched/rt.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/ioport.h>
#include <linux/acpi.h>

#define CREATE_TRACE_POINTS
#include <trace/events/spi.h>

static void spidev_release(struct device *dev)
{
	struct spi_device	*spi = to_spi_device(dev);

	/* spi masters may cleanup for released devices */
	if (spi->master->cleanup)
		spi->master->cleanup(spi);

	spi_master_put(spi->master);
	kfree(spi);
}

static ssize_t
modalias_show(struct device *dev, struct device_attribute *a, char *buf)
{
	const struct spi_device	*spi = to_spi_device(dev);
	int len;

	len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
	if (len != -ENODEV)
		return len;

	return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
}
static DEVICE_ATTR_RO(modalias);

static struct attribute *spi_dev_attrs[] = {
	&dev_attr_modalias.attr,
	NULL,
};
ATTRIBUTE_GROUPS(spi_dev);

/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
 * and the sysfs version makes coldplug work too.
 */

static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
						const struct spi_device *sdev)
{
	while (id->name[0]) {
		if (!strcmp(sdev->modalias, id->name))
			return id;
		id++;
	}
	return NULL;
}

const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
{
	const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);

	return spi_match_id(sdrv->id_table, sdev);
}
EXPORT_SYMBOL_GPL(spi_get_device_id);

static int spi_match_device(struct device *dev, struct device_driver *drv)
{
	const struct spi_device	*spi = to_spi_device(dev);
	const struct spi_driver	*sdrv = to_spi_driver(drv);

	/* Attempt an OF style match */
	if (of_driver_match_device(dev, drv))
		return 1;

	/* Then try ACPI */
	if (acpi_driver_match_device(dev, drv))
		return 1;

	if (sdrv->id_table)
		return !!spi_match_id(sdrv->id_table, spi);

	return strcmp(spi->modalias, drv->name) == 0;
}

static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	const struct spi_device		*spi = to_spi_device(dev);
	int rc;

	rc = acpi_device_uevent_modalias(dev, env);
	if (rc != -ENODEV)
		return rc;

	add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int spi_legacy_suspend(struct device *dev, pm_message_t message)
{
	int			value = 0;
	struct spi_driver	*drv = to_spi_driver(dev->driver);

	/* suspend will stop irqs and dma; no more i/o */
	if (drv) {
		if (drv->suspend)
			value = drv->suspend(to_spi_device(dev), message);
		else
			dev_dbg(dev, "... can't suspend\n");
	}
	return value;
}

static int spi_legacy_resume(struct device *dev)
{
	int			value = 0;
	struct spi_driver	*drv = to_spi_driver(dev->driver);

	/* resume may restart the i/o queue */
	if (drv) {
		if (drv->resume)
			value = drv->resume(to_spi_device(dev));
		else
			dev_dbg(dev, "... can't resume\n");
	}
	return value;
}

static int spi_pm_suspend(struct device *dev)
{
	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

	if (pm)
		return pm_generic_suspend(dev);
	else
		return spi_legacy_suspend(dev, PMSG_SUSPEND);
}

static int spi_pm_resume(struct device *dev)
{
	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

	if (pm)
		return pm_generic_resume(dev);
	else
		return spi_legacy_resume(dev);
}

static int spi_pm_freeze(struct device *dev)
{
	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

	if (pm)
		return pm_generic_freeze(dev);
	else
		return spi_legacy_suspend(dev, PMSG_FREEZE);
}

static int spi_pm_thaw(struct device *dev)
{
	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

	if (pm)
		return pm_generic_thaw(dev);
	else
		return spi_legacy_resume(dev);
}

static int spi_pm_poweroff(struct device *dev)
{
	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

	if (pm)
		return pm_generic_poweroff(dev);
	else
		return spi_legacy_suspend(dev, PMSG_HIBERNATE);
}

static int spi_pm_restore(struct device *dev)
{
	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

	if (pm)
		return pm_generic_restore(dev);
	else
		return spi_legacy_resume(dev);
}
#else
#define spi_pm_suspend	NULL
#define spi_pm_resume	NULL
#define spi_pm_freeze	NULL
#define spi_pm_thaw	NULL
#define spi_pm_poweroff	NULL
#define spi_pm_restore	NULL
#endif

static const struct dev_pm_ops spi_pm = {
	.suspend = spi_pm_suspend,
	.resume = spi_pm_resume,
	.freeze = spi_pm_freeze,
	.thaw = spi_pm_thaw,
	.poweroff = spi_pm_poweroff,
	.restore = spi_pm_restore,
	SET_RUNTIME_PM_OPS(
		pm_generic_runtime_suspend,
		pm_generic_runtime_resume,
		NULL
	)
};

struct bus_type spi_bus_type = {
	.name		= "spi",
	.dev_groups	= spi_dev_groups,
	.match		= spi_match_device,
	.uevent		= spi_uevent,
	.pm		= &spi_pm,
};
EXPORT_SYMBOL_GPL(spi_bus_type);


static int spi_drv_probe(struct device *dev)
{
	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);
	int ret;

	acpi_dev_pm_attach(dev, true);
	ret = sdrv->probe(to_spi_device(dev));
	if (ret)
		acpi_dev_pm_detach(dev, true);

	return ret;
}

static int spi_drv_remove(struct device *dev)
{
	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);
	int ret;

	ret = sdrv->remove(to_spi_device(dev));
	acpi_dev_pm_detach(dev, true);

	return ret;
}

static void spi_drv_shutdown(struct device *dev)
{
	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);

	sdrv->shutdown(to_spi_device(dev));
}

/**
 * spi_register_driver - register a SPI driver
 * @sdrv: the driver to register
 * Context: can sleep
 */
int spi_register_driver(struct spi_driver *sdrv)
{
	sdrv->driver.bus = &spi_bus_type;
	if (sdrv->probe)
		sdrv->driver.probe = spi_drv_probe;
	if (sdrv->remove)
		sdrv->driver.remove = spi_drv_remove;
	if (sdrv->shutdown)
		sdrv->driver.shutdown = spi_drv_shutdown;
	return driver_register(&sdrv->driver);
}
EXPORT_SYMBOL_GPL(spi_register_driver);

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

/* SPI devices should normally not be created by SPI device drivers; that
 * would make them board-specific.  Similarly with SPI master drivers.
 * Device registration normally goes into like arch/.../mach.../board-YYY.c
 * with other readonly (flashable) information about mainboard devices.
 */

struct boardinfo {
	struct list_head	list;
	struct spi_board_info	board_info;
};

static LIST_HEAD(board_list);
static LIST_HEAD(spi_master_list);

/*
 * Used to protect add/del opertion for board_info list and
 * spi_master list, and their matching process
 */
static DEFINE_MUTEX(board_lock);

/**
 * spi_alloc_device - Allocate a new SPI device
 * @master: Controller to which device is connected
 * Context: can sleep
 *
 * Allows a driver to allocate and initialize a spi_device without
 * registering it immediately.  This allows a driver to directly
 * fill the spi_device with device parameters before calling
 * spi_add_device() on it.
 *
 * Caller is responsible to call spi_add_device() on the returned
 * spi_device structure to add it to the SPI master.  If the caller
 * needs to discard the spi_device without adding it, then it should
 * call spi_dev_put() on it.
 *
 * Returns a pointer to the new device, or NULL.
 */
struct spi_device *spi_alloc_device(struct spi_master *master)
{
	struct spi_device	*spi;
	struct device		*dev = master->dev.parent;

	if (!spi_master_get(master))
		return NULL;

	spi = kzalloc(sizeof(*spi), GFP_KERNEL);
	if (!spi) {
		dev_err(dev, "cannot alloc spi_device\n");
		spi_master_put(master);
		return NULL;
	}

	spi->master = master;
	spi->dev.parent = &master->dev;
	spi->dev.bus = &spi_bus_type;
	spi->dev.release = spidev_release;
	spi->cs_gpio = -ENOENT;
	device_initialize(&spi->dev);
	return spi;
}
EXPORT_SYMBOL_GPL(spi_alloc_device);

static void spi_dev_set_name(struct spi_device *spi)
{
	struct acpi_device *adev = ACPI_COMPANION(&spi->dev);

	if (adev) {
		dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
		return;
	}

	dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
		     spi->chip_select);
}

static int spi_dev_check(struct device *dev, void *data)
{
	struct spi_device *spi = to_spi_device(dev);
	struct spi_device *new_spi = data;

	if (spi->master == new_spi->master &&
	    spi->chip_select == new_spi->chip_select)
		return -EBUSY;
	return 0;
}

/**
 * spi_add_device - Add spi_device allocated with spi_alloc_device
 * @spi: spi_device to register
 *
 * Companion function to spi_alloc_device.  Devices allocated with
 * spi_alloc_device can be added onto the spi bus with this function.
 *
 * Returns 0 on success; negative errno on failure
 */
int spi_add_device(struct spi_device *spi)
{
	static DEFINE_MUTEX(spi_add_lock);
	struct spi_master *master = spi->master;
	struct device *dev = master->dev.parent;
	int status;

	/* Chipselects are numbered 0..max; validate. */
	if (spi->chip_select >= master->num_chipselect) {
		dev_err(dev, "cs%d >= max %d\n",
			spi->chip_select,
			master->num_chipselect);
		return -EINVAL;
	}

	/* Set the bus ID string */
	spi_dev_set_name(spi);

	/* We need to make sure there's no other device with this
	 * chipselect **BEFORE** we call setup(), else we'll trash
	 * its configuration.  Lock against concurrent add() calls.
	 */
	mutex_lock(&spi_add_lock);

	status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
	if (status) {
		dev_err(dev, "chipselect %d already in use\n",
				spi->chip_select);
		goto done;
	}

	if (master->cs_gpios)
		spi->cs_gpio = master->cs_gpios[spi->chip_select];

	/* Drivers may modify this initial i/o setup, but will
	 * normally rely on the device being setup.  Devices
	 * using SPI_CS_HIGH can't coexist well otherwise...
	 */
	status = spi_setup(spi);
	if (status < 0) {
		dev_err(dev, "can't setup %s, status %d\n",
				dev_name(&spi->dev), status);
		goto done;
	}

	/* Device may be bound to an active driver when this returns */
	status = device_add(&spi->dev);
	if (status < 0)
		dev_err(dev, "can't add %s, status %d\n",
				dev_name(&spi->dev), status);
	else
		dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));

done:
	mutex_unlock(&spi_add_lock);
	return status;
}
EXPORT_SYMBOL_GPL(spi_add_device);

/**
 * spi_new_device - instantiate one new SPI device
 * @master: Controller to which device is connected
 * @chip: Describes the SPI device
 * Context: can sleep
 *
 * On typical mainboards, this is purely internal; and it's not needed
 * after board init creates the hard-wired devices.  Some development
 * platforms may not be able to use spi_register_board_info though, and
 * this is exported so that for example a USB or parport based adapter
 * driver could add devices (which it would learn about out-of-band).
 *
 * Returns the new device, or NULL.
 */
struct spi_device *spi_new_device(struct spi_master *master,
				  struct spi_board_info *chip)
{
	struct spi_device	*proxy;
	int			status;

	/* NOTE:  caller did any chip->bus_num checks necessary.
	 *
	 * Also, unless we change the return value convention to use
	 * error-or-pointer (not NULL-or-pointer), troubleshootability
	 * suggests syslogged diagnostics are best here (ugh).
	 */

	proxy = spi_alloc_device(master);
	if (!proxy)
		return NULL;

	WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));

	proxy->chip_select = chip->chip_select;
	proxy->max_speed_hz = chip->max_speed_hz;
	proxy->mode = chip->mode;
	proxy->irq = chip->irq;
	strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
	proxy->dev.platform_data = (void *) chip->platform_data;
	proxy->controller_data = chip->controller_data;
	proxy->controller_state = NULL;

	status = spi_add_device(proxy);
	if (status < 0) {
		spi_dev_put(proxy);
		return NULL;
	}

	return proxy;
}
EXPORT_SYMBOL_GPL(spi_new_device);

static void spi_match_master_to_boardinfo(struct spi_master *master,
				struct spi_board_info *bi)
{
	struct spi_device *dev;

	if (master->bus_num != bi->bus_num)
		return;

	dev = spi_new_device(master, bi);
	if (!dev)
		dev_err(master->dev.parent, "can't create new device for %s\n",
			bi->modalias);
}

/**
 * spi_register_board_info - register SPI devices for a given board
 * @info: array of chip descriptors
 * @n: how many descriptors are provided
 * Context: can sleep
 *
 * Board-specific early init code calls this (probably during arch_initcall)
 * with segments of the SPI device table.  Any device nodes are created later,
 * after the relevant parent SPI controller (bus_num) is defined.  We keep
 * this table of devices forever, so that reloading a controller driver will
 * not make Linux forget about these hard-wired devices.
 *
 * Other code can also call this, e.g. a particular add-on board might provide
 * SPI devices through its expansion connector, so code initializing that board
 * would naturally declare its SPI devices.
 *
 * The board info passed can safely be __initdata ... but be careful of
 * any embedded pointers (platform_data, etc), they're copied as-is.
 */
int spi_register_board_info(struct spi_board_info const *info, unsigned n)
{
	struct boardinfo *bi;
	int i;

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

	for (i = 0; i < n; i++, bi++, info++) {
		struct spi_master *master;

		memcpy(&bi->board_info, info, sizeof(*info));
		mutex_lock(&board_lock);
		list_add_tail(&bi->list, &board_list);
		list_for_each_entry(master, &spi_master_list, list)
			spi_match_master_to_boardinfo(master, &bi->board_info);
		mutex_unlock(&board_lock);
	}

	return 0;
}

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

static void spi_set_cs(struct spi_device *spi, bool enable)
{
	if (spi->mode & SPI_CS_HIGH)
		enable = !enable;

	if (spi->cs_gpio >= 0)
		gpio_set_value(spi->cs_gpio, !enable);
	else if (spi->master->set_cs)
		spi->master->set_cs(spi, !enable);
}

static int spi_map_buf(struct spi_master *master, struct device *dev,
		       struct sg_table *sgt, void *buf, size_t len,
		       enum dma_data_direction dir)
{
	const bool vmalloced_buf = is_vmalloc_addr(buf);
	const int desc_len = vmalloced_buf ? PAGE_SIZE : master->max_dma_len;
	const int sgs = DIV_ROUND_UP(len, desc_len);
	struct page *vm_page;
	void *sg_buf;
	size_t min;
	int i, ret;

	ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
	if (ret != 0)
		return ret;

	for (i = 0; i < sgs; i++) {
		min = min_t(size_t, len, desc_len);

		if (vmalloced_buf) {
			vm_page = vmalloc_to_page(buf);
			if (!vm_page) {
				sg_free_table(sgt);
				return -ENOMEM;
			}
			sg_buf = page_address(vm_page) +
				((size_t)buf & ~PAGE_MASK);
		} else {
			sg_buf = buf;
		}

		sg_set_buf(&sgt->sgl[i], sg_buf, min);

		buf += min;
		len -= min;
	}

	ret = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
	if (ret < 0) {
		sg_free_table(sgt);
		return ret;
	}

	sgt->nents = ret;

	return 0;
}

static void spi_unmap_buf(struct spi_master *master, struct device *dev,
			  struct sg_table *sgt, enum dma_data_direction dir)
{
	if (sgt->orig_nents) {
		dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
		sg_free_table(sgt);
	}
}

static int spi_map_msg(struct spi_master *master, struct spi_message *msg)
{
	struct device *tx_dev, *rx_dev;
	struct spi_transfer *xfer;
	void *tmp;
	unsigned int max_tx, max_rx;
	int ret;

	if (master->flags & (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX)) {
		max_tx = 0;
		max_rx = 0;

		list_for_each_entry(xfer, &msg->transfers, transfer_list) {
			if ((master->flags & SPI_MASTER_MUST_TX) &&
			    !xfer->tx_buf)
				max_tx = max(xfer->len, max_tx);
			if ((master->flags & SPI_MASTER_MUST_RX) &&
			    !xfer->rx_buf)
				max_rx = max(xfer->len, max_rx);
		}

		if (max_tx) {
			tmp = krealloc(master->dummy_tx, max_tx,
				       GFP_KERNEL | GFP_DMA);
			if (!tmp)
				return -ENOMEM;
			master->dummy_tx = tmp;
			memset(tmp, 0, max_tx);
		}

		if (max_rx) {
			tmp = krealloc(master->dummy_rx, max_rx,
				       GFP_KERNEL | GFP_DMA);
			if (!tmp)
				return -ENOMEM;
			master->dummy_rx = tmp;
		}

		if (max_tx || max_rx) {
			list_for_each_entry(xfer, &msg->transfers,
					    transfer_list) {
				if (!xfer->tx_buf)
					xfer->tx_buf = master->dummy_tx;
				if (!xfer->rx_buf)
					xfer->rx_buf = master->dummy_rx;
			}
		}
	}

	if (!master->can_dma)
		return 0;

	tx_dev = &master->dma_tx->dev->device;
	rx_dev = &master->dma_rx->dev->device;

	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
		if (!master->can_dma(master, msg->spi, xfer))
			continue;

		if (xfer->tx_buf != NULL) {
			ret = spi_map_buf(master, tx_dev, &xfer->tx_sg,
					  (void *)xfer->tx_buf, xfer->len,
					  DMA_TO_DEVICE);
			if (ret != 0)
				return ret;
		}

		if (xfer->rx_buf != NULL) {
			ret = spi_map_buf(master, rx_dev, &xfer->rx_sg,
					  xfer->rx_buf, xfer->len,
					  DMA_FROM_DEVICE);
			if (ret != 0) {
				spi_unmap_buf(master, tx_dev, &xfer->tx_sg,
					      DMA_TO_DEVICE);
				return ret;
			}
		}
	}

	master->cur_msg_mapped = true;

	return 0;
}

static int spi_unmap_msg(struct spi_master *master, struct spi_message *msg)
{
	struct spi_transfer *xfer;
	struct device *tx_dev, *rx_dev;

	if (!master->cur_msg_mapped || !master->can_dma)
		return 0;

	tx_dev = &master->dma_tx->dev->device;
	rx_dev = &master->dma_rx->dev->device;

	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
		if (!master->can_dma(master, msg->spi, xfer))
			continue;

		spi_unmap_buf(master, rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE);
		spi_unmap_buf(master, tx_dev, &xfer->tx_sg, DMA_TO_DEVICE);
	}

	return 0;
}

/*
 * spi_transfer_one_message - Default implementation of transfer_one_message()
 *
 * This is a standard implementation of transfer_one_message() for
 * drivers which impelment a transfer_one() operation.  It provides
 * standard handling of delays and chip select management.
 */
static int spi_transfer_one_message(struct spi_master *master,
				    struct spi_message *msg)
{
	struct spi_transfer *xfer;
	bool keep_cs = false;
	int ret = 0;

	spi_set_cs(msg->spi, true);

	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
		trace_spi_transfer_start(msg, xfer);

		reinit_completion(&master->xfer_completion);

		ret = master->transfer_one(master, msg->spi, xfer);
		if (ret < 0) {
			dev_err(&msg->spi->dev,
				"SPI transfer failed: %d\n", ret);
			goto out;
		}

		if (ret > 0) {
			ret = 0;
			wait_for_completion(&master->xfer_completion);
		}

		trace_spi_transfer_stop(msg, xfer);

		if (msg->status != -EINPROGRESS)
			goto out;

		if (xfer->delay_usecs)
			udelay(xfer->delay_usecs);

		if (xfer->cs_change) {
			if (list_is_last(&xfer->transfer_list,
					 &msg->transfers)) {
				keep_cs = true;
			} else {
				spi_set_cs(msg->spi, false);
				udelay(10);
				spi_set_cs(msg->spi, true);
			}
		}

		msg->actual_length += xfer->len;
	}

out:
	if (ret != 0 || !keep_cs)
		spi_set_cs(msg->spi, false);

	if (msg->status == -EINPROGRESS)
		msg->status = ret;

	spi_finalize_current_message(master);

	return ret;
}

/**
 * spi_finalize_current_transfer - report completion of a transfer
 *
 * Called by SPI drivers using the core transfer_one_message()
 * implementation to notify it that the current interrupt driven
 * transfer has finished and the next one may be scheduled.
 */
void spi_finalize_current_transfer(struct spi_master *master)
{
	complete(&master->xfer_completion);
}
EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);

/**
 * spi_pump_messages - kthread work function which processes spi message queue
 * @work: pointer to kthread work struct contained in the master struct
 *
 * This function checks if there is any spi message in the queue that
 * needs processing and if so call out to the driver to initialize hardware
 * and transfer each message.
 *
 */
static void spi_pump_messages(struct kthread_work *work)
{
	struct spi_master *master =
		container_of(work, struct spi_master, pump_messages);
	unsigned long flags;
	bool was_busy = false;
	int ret;

	/* Lock queue and check for queue work */
	spin_lock_irqsave(&master->queue_lock, flags);
	if (list_empty(&master->queue) || !master->running) {
		if (!master->busy) {
			spin_unlock_irqrestore(&master->queue_lock, flags);
			return;
		}
		master->busy = false;
		spin_unlock_irqrestore(&master->queue_lock, flags);
		kfree(master->dummy_rx);
		master->dummy_rx = NULL;
		kfree(master->dummy_tx);
		master->dummy_tx = NULL;
		if (master->unprepare_transfer_hardware &&
		    master->unprepare_transfer_hardware(master))
			dev_err(&master->dev,
				"failed to unprepare transfer hardware\n");
		if (master->auto_runtime_pm) {
			pm_runtime_mark_last_busy(master->dev.parent);
			pm_runtime_put_autosuspend(master->dev.parent);
		}
		trace_spi_master_idle(master);
		return;
	}

	/* Make sure we are not already running a message */
	if (master->cur_msg) {
		spin_unlock_irqrestore(&master->queue_lock, flags);
		return;
	}
	/* Extract head of queue */
	master->cur_msg =
		list_first_entry(&master->queue, struct spi_message, queue);

	list_del_init(&master->cur_msg->queue);
	if (master->busy)
		was_busy = true;
	else
		master->busy = true;
	spin_unlock_irqrestore(&master->queue_lock, flags);

	if (!was_busy && master->auto_runtime_pm) {
		ret = pm_runtime_get_sync(master->dev.parent);
		if (ret < 0) {
			dev_err(&master->dev, "Failed to power device: %d\n",
				ret);
			return;
		}
	}

	if (!was_busy)
		trace_spi_master_busy(master);

	if (!was_busy && master->prepare_transfer_hardware) {
		ret = master->prepare_transfer_hardware(master);
		if (ret) {
			dev_err(&master->dev,
				"failed to prepare transfer hardware\n");

			if (master->auto_runtime_pm)
				pm_runtime_put(master->dev.parent);
			return;
		}
	}

	trace_spi_message_start(master->cur_msg);

	if (master->prepare_message) {
		ret = master->prepare_message(master, master->cur_msg);
		if (ret) {
			dev_err(&master->dev,
				"failed to prepare message: %d\n", ret);
			master->cur_msg->status = ret;
			spi_finalize_current_message(master);
			return;
		}
		master->cur_msg_prepared = true;
	}

	ret = spi_map_msg(master, master->cur_msg);
	if (ret) {
		master->cur_msg->status = ret;
		spi_finalize_current_message(master);
		return;
	}

	ret = master->transfer_one_message(master, master->cur_msg);
	if (ret) {
		dev_err(&master->dev,
			"failed to transfer one message from queue\n");
		return;
	}
}

static int spi_init_queue(struct spi_master *master)
{
	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };

	INIT_LIST_HEAD(&master->queue);
	spin_lock_init(&master->queue_lock);

	master->running = false;
	master->busy = false;

	init_kthread_worker(&master->kworker);
	master->kworker_task = kthread_run(kthread_worker_fn,
					   &master->kworker, "%s",
					   dev_name(&master->dev));
	if (IS_ERR(master->kworker_task)) {
		dev_err(&master->dev, "failed to create message pump task\n");
		return -ENOMEM;
	}
	init_kthread_work(&master->pump_messages, spi_pump_messages);

	/*
	 * Master config will indicate if this controller should run the
	 * message pump with high (realtime) priority to reduce the transfer
	 * latency on the bus by minimising the delay between a transfer
	 * request and the scheduling of the message pump thread. Without this
	 * setting the message pump thread will remain at default priority.
	 */
	if (master->rt) {
		dev_info(&master->dev,
			"will run message pump with realtime priority\n");
		sched_setscheduler(master->kworker_task, SCHED_FIFO, &param);
	}

	return 0;
}

/**
 * spi_get_next_queued_message() - called by driver to check for queued
 * messages
 * @master: the master to check for queued messages
 *
 * If there are more messages in the queue, the next message is returned from
 * this call.
 */
struct spi_message *spi_get_next_queued_message(struct spi_master *master)
{
	struct spi_message *next;
	unsigned long flags;

	/* get a pointer to the next message, if any */
	spin_lock_irqsave(&master->queue_lock, flags);
	next = list_first_entry_or_null(&master->queue, struct spi_message,
					queue);
	spin_unlock_irqrestore(&master->queue_lock, flags);

	return next;
}
EXPORT_SYMBOL_GPL(spi_get_next_queued_message);

/**
 * spi_finalize_current_message() - the current message is complete
 * @master: the master to return the message to
 *
 * Called by the driver to notify the core that the message in the front of the
 * queue is complete and can be removed from the queue.
 */
void spi_finalize_current_message(struct spi_master *master)
{
	struct spi_message *mesg;
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&master->queue_lock, flags);
	mesg = master->cur_msg;
	master->cur_msg = NULL;

	queue_kthread_work(&master->kworker, &master->pump_messages);
	spin_unlock_irqrestore(&master->queue_lock, flags);

	spi_unmap_msg(master, mesg);

	if (master->cur_msg_prepared && master->unprepare_message) {
		ret = master->unprepare_message(master, mesg);
		if (ret) {
			dev_err(&master->dev,
				"failed to unprepare message: %d\n", ret);
		}
	}
	master->cur_msg_prepared = false;

	mesg->state = NULL;
	if (mesg->complete)
		mesg->complete(mesg->context);

	trace_spi_message_done(mesg);
}
EXPORT_SYMBOL_GPL(spi_finalize_current_message);

static int spi_start_queue(struct spi_master *master)
{
	unsigned long flags;

	spin_lock_irqsave(&master->queue_lock, flags);

	if (master->running || master->busy) {
		spin_unlock_irqrestore(&master->queue_lock, flags);
		return -EBUSY;
	}

	master->running = true;
	master->cur_msg = NULL;
	spin_unlock_irqrestore(&master->queue_lock, flags);

	queue_kthread_work(&master->kworker, &master->pump_messages);

	return 0;
}

static int spi_stop_queue(struct spi_master *master)
{
	unsigned long flags;
	unsigned limit = 500;
	int ret = 0;

	spin_lock_irqsave(&master->queue_lock, flags);

	/*
	 * This is a bit lame, but is optimized for the common execution path.
	 * A wait_queue on the master->busy could be used, but then the common
	 * execution path (pump_messages) would be required to call wake_up or
	 * friends on every SPI message. Do this instead.
	 */
	while ((!list_empty(&master->queue) || master->busy) && limit--) {
		spin_unlock_irqrestore(&master->queue_lock, flags);
		usleep_range(10000, 11000);
		spin_lock_irqsave(&master->queue_lock, flags);
	}

	if (!list_empty(&master->queue) || master->busy)
		ret = -EBUSY;
	else
		master->running = false;

	spin_unlock_irqrestore(&master->queue_lock, flags);

	if (ret) {
		dev_warn(&master->dev,
			 "could not stop message queue\n");
		return ret;
	}
	return ret;
}

static int spi_destroy_queue(struct spi_master *master)
{
	int ret;

	ret = spi_stop_queue(master);

	/*
	 * flush_kthread_worker will block until all work is done.
	 * If the reason that stop_queue timed out is that the work will never
	 * finish, then it does no good to call flush/stop thread, so
	 * return anyway.
	 */
	if (ret) {
		dev_err(&master->dev, "problem destroying queue\n");
		return ret;
	}

	flush_kthread_worker(&master->kworker);
	kthread_stop(master->kworker_task);

	return 0;
}

/**
 * spi_queued_transfer - transfer function for queued transfers
 * @spi: spi device which is requesting transfer
 * @msg: spi message which is to handled is queued to driver queue
 */
static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
{
	struct spi_master *master = spi->master;
	unsigned long flags;

	spin_lock_irqsave(&master->queue_lock, flags);

	if (!master->running) {
		spin_unlock_irqrestore(&master->queue_lock, flags);
		return -ESHUTDOWN;
	}
	msg->actual_length = 0;
	msg->status = -EINPROGRESS;

	list_add_tail(&msg->queue, &master->queue);
	if (!master->busy)
		queue_kthread_work(&master->kworker, &master->pump_messages);

	spin_unlock_irqrestore(&master->queue_lock, flags);
	return 0;
}

static int spi_master_initialize_queue(struct spi_master *master)
{
	int ret;

	master->queued = true;
	master->transfer = spi_queued_transfer;
	if (!master->transfer_one_message)
		master->transfer_one_message = spi_transfer_one_message;

	/* Initialize and start queue */
	ret = spi_init_queue(master);
	if (ret) {
		dev_err(&master->dev, "problem initializing queue\n");
		goto err_init_queue;
	}
	ret = spi_start_queue(master);
	if (ret) {
		dev_err(&master->dev, "problem starting queue\n");
		goto err_start_queue;
	}

	return 0;

err_start_queue:
err_init_queue:
	spi_destroy_queue(master);
	return ret;
}

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

#if defined(CONFIG_OF)
/**
 * of_register_spi_devices() - Register child devices onto the SPI bus
 * @master:	Pointer to spi_master device
 *
 * Registers an spi_device for each child node of master node which has a 'reg'
 * property.
 */
static void of_register_spi_devices(struct spi_master *master)
{
	struct spi_device *spi;
	struct device_node *nc;
	int rc;
	u32 value;

	if (!master->dev.of_node)
		return;

	for_each_available_child_of_node(master->dev.of_node, nc) {
		/* Alloc an spi_device */
		spi = spi_alloc_device(master);
		if (!spi) {
			dev_err(&master->dev, "spi_device alloc error for %s\n",
				nc->full_name);
			spi_dev_put(spi);
			continue;
		}

		/* Select device driver */
		if (of_modalias_node(nc, spi->modalias,
				     sizeof(spi->modalias)) < 0) {
			dev_err(&master->dev, "cannot find modalias for %s\n",
				nc->full_name);
			spi_dev_put(spi);
			continue;
		}

		/* Device address */
		rc = of_property_read_u32(nc, "reg", &value);
		if (rc) {
			dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
				nc->full_name, rc);
			spi_dev_put(spi);
			continue;
		}
		spi->chip_select = value;

		/* Mode (clock phase/polarity/etc.) */
		if (of_find_property(nc, "spi-cpha", NULL))
			spi->mode |= SPI_CPHA;
		if (of_find_property(nc, "spi-cpol", NULL))
			spi->mode |= SPI_CPOL;
		if (of_find_property(nc, "spi-cs-high", NULL))
			spi->mode |= SPI_CS_HIGH;
		if (of_find_property(nc, "spi-3wire", NULL))
			spi->mode |= SPI_3WIRE;

		/* Device DUAL/QUAD mode */
		if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
			switch (value) {
			case 1:
				break;
			case 2:
				spi->mode |= SPI_TX_DUAL;
				break;
			case 4:
				spi->mode |= SPI_TX_QUAD;
				break;
			default:
				dev_err(&master->dev,
					"spi-tx-bus-width %d not supported\n",
					value);
				spi_dev_put(spi);
				continue;
			}
		}

		if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
			switch (value) {
			case 1:
				break;
			case 2:
				spi->mode |= SPI_RX_DUAL;
				break;
			case 4:
				spi->mode |= SPI_RX_QUAD;
				break;
			default:
				dev_err(&master->dev,
					"spi-rx-bus-width %d not supported\n",
					value);
				spi_dev_put(spi);
				continue;
			}
		}

		/* Device speed */
		rc = of_property_read_u32(nc, "spi-max-frequency", &value);
		if (rc) {
			dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
				nc->full_name, rc);
			spi_dev_put(spi);
			continue;
		}
		spi->max_speed_hz = value;

		/* IRQ */
		spi->irq = irq_of_parse_and_map(nc, 0);

		/* Store a pointer to the node in the device structure */
		of_node_get(nc);
		spi->dev.of_node = nc;

		/* Register the new device */
		request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
		rc = spi_add_device(spi);
		if (rc) {
			dev_err(&master->dev, "spi_device register error %s\n",
				nc->full_name);
			spi_dev_put(spi);
		}

	}
}
#else
static void of_register_spi_devices(struct spi_master *master) { }
#endif

#ifdef CONFIG_ACPI
static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
{
	struct spi_device *spi = data;

	if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
		struct acpi_resource_spi_serialbus *sb;

		sb = &ares->data.spi_serial_bus;
		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
			spi->chip_select = sb->device_selection;
			spi->max_speed_hz = sb->connection_speed;

			if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
				spi->mode |= SPI_CPHA;
			if (sb->clock_polarity == ACPI_SPI_START_HIGH)
				spi->mode |= SPI_CPOL;
			if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
				spi->mode |= SPI_CS_HIGH;
		}
	} else if (spi->irq < 0) {
		struct resource r;

		if (acpi_dev_resource_interrupt(ares, 0, &r))
			spi->irq = r.start;
	}

	/* Always tell the ACPI core to skip this resource */
	return 1;
}

static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
				       void *data, void **return_value)
{
	struct spi_master *master = data;
	struct list_head resource_list;
	struct acpi_device *adev;
	struct spi_device *spi;
	int ret;

	if (acpi_bus_get_device(handle, &adev))
		return AE_OK;
	if (acpi_bus_get_status(adev) || !adev->status.present)
		return AE_OK;

	spi = spi_alloc_device(master);
	if (!spi) {
		dev_err(&master->dev, "failed to allocate SPI device for %s\n",
			dev_name(&adev->dev));
		return AE_NO_MEMORY;
	}

	ACPI_COMPANION_SET(&spi->dev, adev);
	spi->irq = -1;

	INIT_LIST_HEAD(&resource_list);
	ret = acpi_dev_get_resources(adev, &resource_list,
				     acpi_spi_add_resource, spi);
	acpi_dev_free_resource_list(&resource_list);

	if (ret < 0 || !spi->max_speed_hz) {
		spi_dev_put(spi);
		return AE_OK;
	}

	adev->power.flags.ignore_parent = true;
	strlcpy(spi->modalias, acpi_device_hid(adev), sizeof(spi->modalias));
	if (spi_add_device(spi)) {
		adev->power.flags.ignore_parent = false;
		dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
			dev_name(&adev->dev));
		spi_dev_put(spi);
	}

	return AE_OK;
}

static void acpi_register_spi_devices(struct spi_master *master)
{
	acpi_status status;
	acpi_handle handle;

	handle = ACPI_HANDLE(master->dev.parent);
	if (!handle)
		return;

	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
				     acpi_spi_add_device, NULL,
				     master, NULL);
	if (ACPI_FAILURE(status))
		dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
}
#else
static inline void acpi_register_spi_devices(struct spi_master *master) {}
#endif /* CONFIG_ACPI */

static void spi_master_release(struct device *dev)
{
	struct spi_master *master;

	master = container_of(dev, struct spi_master, dev);
	kfree(master);
}

static struct class spi_master_class = {
	.name		= "spi_master",
	.owner		= THIS_MODULE,
	.dev_release	= spi_master_release,
};



/**
 * spi_alloc_master - allocate SPI master controller
 * @dev: the controller, possibly using the platform_bus
 * @size: how much zeroed driver-private data to allocate; the pointer to this
 *	memory is in the driver_data field of the returned device,
 *	accessible with spi_master_get_devdata().
 * Context: can sleep
 *
 * This call is used only by SPI master controller drivers, which are the
 * only ones directly touching chip registers.  It's how they allocate
 * an spi_master structure, prior to calling spi_register_master().
 *
 * This must be called from context that can sleep.  It returns the SPI
 * master structure on success, else NULL.
 *
 * The caller is responsible for assigning the bus number and initializing
 * the master's methods before calling spi_register_master(); and (after errors
 * adding the device) calling spi_master_put() and kfree() to prevent a memory
 * leak.
 */
struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
{
	struct spi_master	*master;

	if (!dev)
		return NULL;

	master = kzalloc(size + sizeof(*master), GFP_KERNEL);
	if (!master)
		return NULL;

	device_initialize(&master->dev);
	master->bus_num = -1;
	master->num_chipselect = 1;
	master->dev.class = &spi_master_class;
	master->dev.parent = get_device(dev);
	spi_master_set_devdata(master, &master[1]);

	return master;
}
EXPORT_SYMBOL_GPL(spi_alloc_master);

#ifdef CONFIG_OF
static int of_spi_register_master(struct spi_master *master)
{
	int nb, i, *cs;
	struct device_node *np = master->dev.of_node;

	if (!np)
		return 0;

	nb = of_gpio_named_count(np, "cs-gpios");
	master->num_chipselect = max_t(int, nb, master->num_chipselect);

	/* Return error only for an incorrectly formed cs-gpios property */
	if (nb == 0 || nb == -ENOENT)
		return 0;
	else if (nb < 0)
		return nb;

	cs = devm_kzalloc(&master->dev,
			  sizeof(int) * master->num_chipselect,
			  GFP_KERNEL);
	master->cs_gpios = cs;

	if (!master->cs_gpios)
		return -ENOMEM;

	for (i = 0; i < master->num_chipselect; i++)
		cs[i] = -ENOENT;

	for (i = 0; i < nb; i++)
		cs[i] = of_get_named_gpio(np, "cs-gpios", i);

	return 0;
}
#else
static int of_spi_register_master(struct spi_master *master)
{
	return 0;
}
#endif

/**
 * spi_register_master - register SPI master controller
 * @master: initialized master, originally from spi_alloc_master()
 * Context: can sleep
 *
 * SPI master controllers connect to their drivers using some non-SPI bus,
 * such as the platform bus.  The final stage of probe() in that code
 * includes calling spi_register_master() to hook up to this SPI bus glue.
 *
 * SPI controllers use board specific (often SOC specific) bus numbers,
 * and board-specific addressing for SPI devices combines those numbers
 * with chip select numbers.  Since SPI does not directly support dynamic
 * device identification, boards need configuration tables telling which
 * chip is at which address.
 *
 * This must be called from context that can sleep.  It returns zero on
 * success, else a negative error code (dropping the master's refcount).
 * After a successful return, the caller is responsible for calling
 * spi_unregister_master().
 */
int spi_register_master(struct spi_master *master)
{
	static atomic_t		dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
	struct device		*dev = master->dev.parent;
	struct boardinfo	*bi;
	int			status = -ENODEV;
	int			dynamic = 0;

	if (!dev)
		return -ENODEV;

	status = of_spi_register_master(master);
	if (status)
		return status;

	/* even if it's just one always-selected device, there must
	 * be at least one chipselect
	 */
	if (master->num_chipselect == 0)
		return -EINVAL;

	if ((master->bus_num < 0) && master->dev.of_node)
		master->bus_num = of_alias_get_id(master->dev.of_node, "spi");

	/* convention:  dynamically assigned bus IDs count down from the max */
	if (master->bus_num < 0) {
		/* FIXME switch to an IDR based scheme, something like
		 * I2C now uses, so we can't run out of "dynamic" IDs
		 */
		master->bus_num = atomic_dec_return(&dyn_bus_id);
		dynamic = 1;
	}

	spin_lock_init(&master->bus_lock_spinlock);
	mutex_init(&master->bus_lock_mutex);
	master->bus_lock_flag = 0;
	init_completion(&master->xfer_completion);
	if (!master->max_dma_len)
		master->max_dma_len = INT_MAX;

	/* register the device, then userspace will see it.
	 * registration fails if the bus ID is in use.
	 */
	dev_set_name(&master->dev, "spi%u", master->bus_num);
	status = device_add(&master->dev);
	if (status < 0)
		goto done;
	dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
			dynamic ? " (dynamic)" : "");

	/* If we're using a queued driver, start the queue */
	if (master->transfer)
		dev_info(dev, "master is unqueued, this is deprecated\n");
	else {
		status = spi_master_initialize_queue(master);
		if (status) {
			device_del(&master->dev);
			goto done;
		}
	}

	mutex_lock(&board_lock);
	list_add_tail(&master->list, &spi_master_list);
	list_for_each_entry(bi, &board_list, list)
		spi_match_master_to_boardinfo(master, &bi->board_info);
	mutex_unlock(&board_lock);

	/* Register devices from the device tree and ACPI */
	of_register_spi_devices(master);
	acpi_register_spi_devices(master);
done:
	return status;
}
EXPORT_SYMBOL_GPL(spi_register_master);

static void devm_spi_unregister(struct device *dev, void *res)
{
	spi_unregister_master(*(struct spi_master **)res);
}

/**
 * dev_spi_register_master - register managed SPI master controller
 * @dev:    device managing SPI master
 * @master: initialized master, originally from spi_alloc_master()
 * Context: can sleep
 *
 * Register a SPI device as with spi_register_master() which will
 * automatically be unregister
 */
int devm_spi_register_master(struct device *dev, struct spi_master *master)
{
	struct spi_master **ptr;
	int ret;

	ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return -ENOMEM;

	ret = spi_register_master(master);
	if (!ret) {
		*ptr = master;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
	}

	return ret;
}
EXPORT_SYMBOL_GPL(devm_spi_register_master);

static int __unregister(struct device *dev, void *null)
{
	spi_unregister_device(to_spi_device(dev));
	return 0;
}

/**
 * spi_unregister_master - unregister SPI master controller
 * @master: the master being unregistered
 * Context: can sleep
 *
 * This call is used only by SPI master controller drivers, which are the
 * only ones directly touching chip registers.
 *
 * This must be called from context that can sleep.
 */
void spi_unregister_master(struct spi_master *master)
{
	int dummy;

	if (master->queued) {
		if (spi_destroy_queue(master))
			dev_err(&master->dev, "queue remove failed\n");
	}

	mutex_lock(&board_lock);
	list_del(&master->list);
	mutex_unlock(&board_lock);

	dummy = device_for_each_child(&master->dev, NULL, __unregister);
	device_unregister(&master->dev);
}
EXPORT_SYMBOL_GPL(spi_unregister_master);

int spi_master_suspend(struct spi_master *master)
{
	int ret;

	/* Basically no-ops for non-queued masters */
	if (!master->queued)
		return 0;

	ret = spi_stop_queue(master);
	if (ret)
		dev_err(&master->dev, "queue stop failed\n");

	return ret;
}
EXPORT_SYMBOL_GPL(spi_master_suspend);

int spi_master_resume(struct spi_master *master)
{
	int ret;

	if (!master->queued)
		return 0;

	ret = spi_start_queue(master);
	if (ret)
		dev_err(&master->dev, "queue restart failed\n");

	return ret;
}
EXPORT_SYMBOL_GPL(spi_master_resume);

static int __spi_master_match(struct device *dev, const void *data)
{
	struct spi_master *m;
	const u16 *bus_num = data;

	m = container_of(dev, struct spi_master, dev);
	return m->bus_num == *bus_num;
}

/**
 * spi_busnum_to_master - look up master associated with bus_num
 * @bus_num: the master's bus number
 * Context: can sleep
 *
 * This call may be used with devices that are registered after
 * arch init time.  It returns a refcounted pointer to the relevant
 * spi_master (which the caller must release), or NULL if there is
 * no such master registered.
 */
struct spi_master *spi_busnum_to_master(u16 bus_num)
{
	struct device		*dev;
	struct spi_master	*master = NULL;

	dev = class_find_device(&spi_master_class, NULL, &bus_num,
				__spi_master_match);
	if (dev)
		master = container_of(dev, struct spi_master, dev);
	/* reference got in class_find_device */
	return master;
}
EXPORT_SYMBOL_GPL(spi_busnum_to_master);


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

/* Core methods for SPI master protocol drivers.  Some of the
 * other core methods are currently defined as inline functions.
 */

/**
 * spi_setup - setup SPI mode and clock rate
 * @spi: the device whose settings are being modified
 * Context: can sleep, and no requests are queued to the device
 *
 * SPI protocol drivers may need to update the transfer mode if the
 * device doesn't work with its default.  They may likewise need
 * to update clock rates or word sizes from initial values.  This function
 * changes those settings, and must be called from a context that can sleep.
 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
 * effect the next time the device is selected and data is transferred to
 * or from it.  When this function returns, the spi device is deselected.
 *
 * Note that this call will fail if the protocol driver specifies an option
 * that the underlying controller or its driver does not support.  For
 * example, not all hardware supports wire transfers using nine bit words,
 * LSB-first wire encoding, or active-high chipselects.
 */
int spi_setup(struct spi_device *spi)
{
	unsigned	bad_bits;
	int		status = 0;

	/* check mode to prevent that DUAL and QUAD set at the same time
	 */
	if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
		((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
		dev_err(&spi->dev,
		"setup: can not select dual and quad at the same time\n");
		return -EINVAL;
	}
	/* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
	 */
	if ((spi->mode & SPI_3WIRE) && (spi->mode &
		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
		return -EINVAL;
	/* help drivers fail *cleanly* when they need options
	 * that aren't supported with their current master
	 */
	bad_bits = spi->mode & ~spi->master->mode_bits;
	if (bad_bits) {
		dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
			bad_bits);
		return -EINVAL;
	}

	if (!spi->bits_per_word)
		spi->bits_per_word = 8;

	if (spi->master->setup)
		status = spi->master->setup(spi);

	dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
			(int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
			(spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
			(spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
			(spi->mode & SPI_3WIRE) ? "3wire, " : "",
			(spi->mode & SPI_LOOP) ? "loopback, " : "",
			spi->bits_per_word, spi->max_speed_hz,
			status);

	return status;
}
EXPORT_SYMBOL_GPL(spi_setup);

static int __spi_validate(struct spi_device *spi, struct spi_message *message)
{
	struct spi_master *master = spi->master;
	struct spi_transfer *xfer;
	int w_size;

	if (list_empty(&message->transfers))
		return -EINVAL;

	/* Half-duplex links include original MicroWire, and ones with
	 * only one data pin like SPI_3WIRE (switches direction) or where
	 * either MOSI or MISO is missing.  They can also be caused by
	 * software limitations.
	 */
	if ((master->flags & SPI_MASTER_HALF_DUPLEX)
			|| (spi->mode & SPI_3WIRE)) {
		unsigned flags = master->flags;

		list_for_each_entry(xfer, &message->transfers, transfer_list) {
			if (xfer->rx_buf && xfer->tx_buf)
				return -EINVAL;
			if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
				return -EINVAL;
			if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
				return -EINVAL;
		}
	}

	/**
	 * Set transfer bits_per_word and max speed as spi device default if
	 * it is not set for this transfer.
	 * Set transfer tx_nbits and rx_nbits as single transfer default
	 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
	 */
	list_for_each_entry(xfer, &message->transfers, transfer_list) {
		message->frame_length += xfer->len;
		if (!xfer->bits_per_word)
			xfer->bits_per_word = spi->bits_per_word;

		if (!xfer->speed_hz)
			xfer->speed_hz = spi->max_speed_hz;

		if (master->max_speed_hz &&
		    xfer->speed_hz > master->max_speed_hz)
			xfer->speed_hz = master->max_speed_hz;

		if (master->bits_per_word_mask) {
			/* Only 32 bits fit in the mask */
			if (xfer->bits_per_word > 32)
				return -EINVAL;
			if (!(master->bits_per_word_mask &
					BIT(xfer->bits_per_word - 1)))
				return -EINVAL;
		}

		/*
		 * SPI transfer length should be multiple of SPI word size
		 * where SPI word size should be power-of-two multiple
		 */
		if (xfer->bits_per_word <= 8)
			w_size = 1;
		else if (xfer->bits_per_word <= 16)
			w_size = 2;
		else
			w_size = 4;

		/* No partial transfers accepted */
		if (xfer->len % w_size)
			return -EINVAL;

		if (xfer->speed_hz && master->min_speed_hz &&
		    xfer->speed_hz < master->min_speed_hz)
			return -EINVAL;

		if (xfer->tx_buf && !xfer->tx_nbits)
			xfer->tx_nbits = SPI_NBITS_SINGLE;
		if (xfer->rx_buf && !xfer->rx_nbits)
			xfer->rx_nbits = SPI_NBITS_SINGLE;
		/* check transfer tx/rx_nbits:
		 * 1. check the value matches one of single, dual and quad
		 * 2. check tx/rx_nbits match the mode in spi_device
		 */
		if (xfer->tx_buf) {
			if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
				xfer->tx_nbits != SPI_NBITS_DUAL &&
				xfer->tx_nbits != SPI_NBITS_QUAD)
				return -EINVAL;
			if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
				!(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
				return -EINVAL;
			if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
				!(spi->mode & SPI_TX_QUAD))
				return -EINVAL;
		}
		/* check transfer rx_nbits */
		if (xfer->rx_buf) {
			if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
				xfer->rx_nbits != SPI_NBITS_DUAL &&
				xfer->rx_nbits != SPI_NBITS_QUAD)
				return -EINVAL;
			if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
				!(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
				return -EINVAL;
			if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
				!(spi->mode & SPI_RX_QUAD))
				return -EINVAL;
		}
	}

	message->status = -EINPROGRESS;

	return 0;
}

static int __spi_async(struct spi_device *spi, struct spi_message *message)
{
	struct spi_master *master = spi->master;

	message->spi = spi;

	trace_spi_message_submit(message);

	return master->transfer(spi, message);
}

/**
 * spi_async - asynchronous SPI transfer
 * @spi: device with which data will be exchanged
 * @message: describes the data transfers, including completion callback
 * Context: any (irqs may be blocked, etc)
 *
 * This call may be used in_irq and other contexts which can't sleep,
 * as well as from task contexts which can sleep.
 *
 * The completion callback is invoked in a context which can't sleep.
 * Before that invocation, the value of message->status is undefined.
 * When the callback is issued, message->status holds either zero (to
 * indicate complete success) or a negative error code.  After that
 * callback returns, the driver which issued the transfer request may
 * deallocate the associated memory; it's no longer in use by any SPI
 * core or controller driver code.
 *
 * Note that although all messages to a spi_device are handled in
 * FIFO order, messages may go to different devices in other orders.
 * Some device might be higher priority, or have various "hard" access
 * time requirements, for example.
 *
 * On detection of any fault during the transfer, processing of
 * the entire message is aborted, and the device is deselected.
 * Until returning from the associated message completion callback,
 * no other spi_message queued to that device will be processed.
 * (This rule applies equally to all the synchronous transfer calls,
 * which are wrappers around this core asynchronous primitive.)
 */
int spi_async(struct spi_device *spi, struct spi_message *message)
{
	struct spi_master *master = spi->master;
	int ret;
	unsigned long flags;

	ret = __spi_validate(spi, message);
	if (ret != 0)
		return ret;

	spin_lock_irqsave(&master->bus_lock_spinlock, flags);

	if (master->bus_lock_flag)
		ret = -EBUSY;
	else
		ret = __spi_async(spi, message);

	spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);

	return ret;
}
EXPORT_SYMBOL_GPL(spi_async);

/**
 * spi_async_locked - version of spi_async with exclusive bus usage
 * @spi: device with which data will be exchanged
 * @message: describes the data transfers, including completion callback
 * Context: any (irqs may be blocked, etc)
 *
 * This call may be used in_irq and other contexts which can't sleep,
 * as well as from task contexts which can sleep.
 *
 * The completion callback is invoked in a context which can't sleep.
 * Before that invocation, the value of message->status is undefined.
 * When the callback is issued, message->status holds either zero (to
 * indicate complete success) or a negative error code.  After that
 * callback returns, the driver which issued the transfer request may
 * deallocate the associated memory; it's no longer in use by any SPI
 * core or controller driver code.
 *
 * Note that although all messages to a spi_device are handled in
 * FIFO order, messages may go to different devices in other orders.
 * Some device might be higher priority, or have various "hard" access
 * time requirements, for example.
 *
 * On detection of any fault during the transfer, processing of
 * the entire message is aborted, and the device is deselected.
 * Until returning from the associated message completion callback,
 * no other spi_message queued to that device will be processed.
 * (This rule applies equally to all the synchronous transfer calls,
 * which are wrappers around this core asynchronous primitive.)
 */
int spi_async_locked(struct spi_device *spi, struct spi_message *message)
{
	struct spi_master *master = spi->master;
	int ret;
	unsigned long flags;

	ret = __spi_validate(spi, message);
	if (ret != 0)
		return ret;

	spin_lock_irqsave(&master->bus_lock_spinlock, flags);

	ret = __spi_async(spi, message);

	spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);

	return ret;

}
EXPORT_SYMBOL_GPL(spi_async_locked);


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

/* Utility methods for SPI master protocol drivers, layered on
 * top of the core.  Some other utility methods are defined as
 * inline functions.
 */

static void spi_complete(void *arg)
{
	complete(arg);
}

static int __spi_sync(struct spi_device *spi, struct spi_message *message,
		      int bus_locked)
{
	DECLARE_COMPLETION_ONSTACK(done);
	int status;
	struct spi_master *master = spi->master;

	message->complete = spi_complete;
	message->context = &done;

	if (!bus_locked)
		mutex_lock(&master->bus_lock_mutex);

	status = spi_async_locked(spi, message);

	if (!bus_locked)
		mutex_unlock(&master->bus_lock_mutex);

	if (status == 0) {
		wait_for_completion(&done);
		status = message->status;
	}
	message->context = NULL;
	return status;
}

/**
 * spi_sync - blocking/synchronous SPI data transfers
 * @spi: device with which data will be exchanged
 * @message: describes the data transfers
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.  Low-overhead controller
 * drivers may DMA directly into and out of the message buffers.
 *
 * Note that the SPI device's chip select is active during the message,
 * and then is normally disabled between messages.  Drivers for some
 * frequently-used devices may want to minimize costs of selecting a chip,
 * by leaving it selected in anticipation that the next message will go
 * to the same chip.  (That may increase power usage.)
 *
 * Also, the caller is guaranteeing that the memory associated with the
 * message will not be freed before this call returns.
 *
 * It returns zero on success, else a negative error code.
 */
int spi_sync(struct spi_device *spi, struct spi_message *message)
{
	return __spi_sync(spi, message, 0);
}
EXPORT_SYMBOL_GPL(spi_sync);

/**
 * spi_sync_locked - version of spi_sync with exclusive bus usage
 * @spi: device with which data will be exchanged
 * @message: describes the data transfers
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.  Low-overhead controller
 * drivers may DMA directly into and out of the message buffers.
 *
 * This call should be used by drivers that require exclusive access to the
 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
 * be released by a spi_bus_unlock call when the exclusive access is over.
 *
 * It returns zero on success, else a negative error code.
 */
int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
{
	return __spi_sync(spi, message, 1);
}
EXPORT_SYMBOL_GPL(spi_sync_locked);

/**
 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
 * @master: SPI bus master that should be locked for exclusive bus access
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.
 *
 * This call should be used by drivers that require exclusive access to the
 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
 * exclusive access is over. Data transfer must be done by spi_sync_locked
 * and spi_async_locked calls when the SPI bus lock is held.
 *
 * It returns zero on success, else a negative error code.
 */
int spi_bus_lock(struct spi_master *master)
{
	unsigned long flags;

	mutex_lock(&master->bus_lock_mutex);

	spin_lock_irqsave(&master->bus_lock_spinlock, flags);
	master->bus_lock_flag = 1;
	spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);

	/* mutex remains locked until spi_bus_unlock is called */

	return 0;
}
EXPORT_SYMBOL_GPL(spi_bus_lock);

/**
 * spi_bus_unlock - release the lock for exclusive SPI bus usage
 * @master: SPI bus master that was locked for exclusive bus access
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.
 *
 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
 * call.
 *
 * It returns zero on success, else a negative error code.
 */
int spi_bus_unlock(struct spi_master *master)
{
	master->bus_lock_flag = 0;

	mutex_unlock(&master->bus_lock_mutex);

	return 0;
}
EXPORT_SYMBOL_GPL(spi_bus_unlock);

/* portable code must never pass more than 32 bytes */
#define	SPI_BUFSIZ	max(32, SMP_CACHE_BYTES)

static u8	*buf;

/**
 * spi_write_then_read - SPI synchronous write followed by read
 * @spi: device with which data will be exchanged
 * @txbuf: data to be written (need not be dma-safe)
 * @n_tx: size of txbuf, in bytes
 * @rxbuf: buffer into which data will be read (need not be dma-safe)
 * @n_rx: size of rxbuf, in bytes
 * Context: can sleep
 *
 * This performs a half duplex MicroWire style transaction with the
 * device, sending txbuf and then reading rxbuf.  The return value
 * is zero for success, else a negative errno status code.
 * This call may only be used from a context that may sleep.
 *
 * Parameters to this routine are always copied using a small buffer;
 * portable code should never use this for more than 32 bytes.
 * Performance-sensitive or bulk transfer code should instead use
 * spi_{async,sync}() calls with dma-safe buffers.
 */
int spi_write_then_read(struct spi_device *spi,
		const void *txbuf, unsigned n_tx,
		void *rxbuf, unsigned n_rx)
{
	static DEFINE_MUTEX(lock);

	int			status;
	struct spi_message	message;
	struct spi_transfer	x[2];
	u8			*local_buf;

	/* Use preallocated DMA-safe buffer if we can.  We can't avoid
	 * copying here, (as a pure convenience thing), but we can
	 * keep heap costs out of the hot path unless someone else is
	 * using the pre-allocated buffer or the transfer is too large.
	 */
	if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
		local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
				    GFP_KERNEL | GFP_DMA);
		if (!local_buf)
			return -ENOMEM;
	} else {
		local_buf = buf;
	}

	spi_message_init(&message);
	memset(x, 0, sizeof(x));
	if (n_tx) {
		x[0].len = n_tx;
		spi_message_add_tail(&x[0], &message);
	}
	if (n_rx) {
		x[1].len = n_rx;
		spi_message_add_tail(&x[1], &message);
	}

	memcpy(local_buf, txbuf, n_tx);
	x[0].tx_buf = local_buf;
	x[1].rx_buf = local_buf + n_tx;

	/* do the i/o */
	status = spi_sync(spi, &message);
	if (status == 0)
		memcpy(rxbuf, x[1].rx_buf, n_rx);

	if (x[0].tx_buf == buf)
		mutex_unlock(&lock);
	else
		kfree(local_buf);

	return status;
}
EXPORT_SYMBOL_GPL(spi_write_then_read);

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

static int __init spi_init(void)
{
	int	status;

	buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
	if (!buf) {
		status = -ENOMEM;
		goto err0;
	}

	status = bus_register(&spi_bus_type);
	if (status < 0)
		goto err1;

	status = class_register(&spi_master_class);
	if (status < 0)
		goto err2;
	return 0;

err2:
	bus_unregister(&spi_bus_type);
err1:
	kfree(buf);
	buf = NULL;
err0:
	return status;
}

/* board_info is normally registered in arch_initcall(),
 * but even essential drivers wait till later
 *
 * REVISIT only boardinfo really needs static linking. the rest (device and
 * driver registration) _could_ be dynamically linked (modular) ... costs
 * include needing to have boardinfo data structures be much more public.
 */
postcore_initcall(spi_init);