summaryrefslogtreecommitdiff
path: root/drivers/mtd/nand/qcom_nandc.c
blob: de7d28e62d4e5aeee107894b8f9a11c66f63ed66 (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
/*
 * Copyright (c) 2016, The Linux Foundation. All rights reserved.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/bitops.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/module.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/delay.h>

/* NANDc reg offsets */
#define	NAND_FLASH_CMD			0x00
#define	NAND_ADDR0			0x04
#define	NAND_ADDR1			0x08
#define	NAND_FLASH_CHIP_SELECT		0x0c
#define	NAND_EXEC_CMD			0x10
#define	NAND_FLASH_STATUS		0x14
#define	NAND_BUFFER_STATUS		0x18
#define	NAND_DEV0_CFG0			0x20
#define	NAND_DEV0_CFG1			0x24
#define	NAND_DEV0_ECC_CFG		0x28
#define	NAND_DEV1_ECC_CFG		0x2c
#define	NAND_DEV1_CFG0			0x30
#define	NAND_DEV1_CFG1			0x34
#define	NAND_READ_ID			0x40
#define	NAND_READ_STATUS		0x44
#define	NAND_DEV_CMD0			0xa0
#define	NAND_DEV_CMD1			0xa4
#define	NAND_DEV_CMD2			0xa8
#define	NAND_DEV_CMD_VLD		0xac
#define	SFLASHC_BURST_CFG		0xe0
#define	NAND_ERASED_CW_DETECT_CFG	0xe8
#define	NAND_ERASED_CW_DETECT_STATUS	0xec
#define	NAND_EBI2_ECC_BUF_CFG		0xf0
#define	FLASH_BUF_ACC			0x100

#define	NAND_CTRL			0xf00
#define	NAND_VERSION			0xf08
#define	NAND_READ_LOCATION_0		0xf20
#define	NAND_READ_LOCATION_1		0xf24

/* dummy register offsets, used by write_reg_dma */
#define	NAND_DEV_CMD1_RESTORE		0xdead
#define	NAND_DEV_CMD_VLD_RESTORE	0xbeef

/* NAND_FLASH_CMD bits */
#define	PAGE_ACC			BIT(4)
#define	LAST_PAGE			BIT(5)

/* NAND_FLASH_CHIP_SELECT bits */
#define	NAND_DEV_SEL			0
#define	DM_EN				BIT(2)

/* NAND_FLASH_STATUS bits */
#define	FS_OP_ERR			BIT(4)
#define	FS_READY_BSY_N			BIT(5)
#define	FS_MPU_ERR			BIT(8)
#define	FS_DEVICE_STS_ERR		BIT(16)
#define	FS_DEVICE_WP			BIT(23)

/* NAND_BUFFER_STATUS bits */
#define	BS_UNCORRECTABLE_BIT		BIT(8)
#define	BS_CORRECTABLE_ERR_MSK		0x1f

/* NAND_DEVn_CFG0 bits */
#define	DISABLE_STATUS_AFTER_WRITE	4
#define	CW_PER_PAGE			6
#define	UD_SIZE_BYTES			9
#define	ECC_PARITY_SIZE_BYTES_RS	19
#define	SPARE_SIZE_BYTES		23
#define	NUM_ADDR_CYCLES			27
#define	STATUS_BFR_READ			30
#define	SET_RD_MODE_AFTER_STATUS	31

/* NAND_DEVn_CFG0 bits */
#define	DEV0_CFG1_ECC_DISABLE		0
#define	WIDE_FLASH			1
#define	NAND_RECOVERY_CYCLES		2
#define	CS_ACTIVE_BSY			5
#define	BAD_BLOCK_BYTE_NUM		6
#define	BAD_BLOCK_IN_SPARE_AREA		16
#define	WR_RD_BSY_GAP			17
#define	ENABLE_BCH_ECC			27

/* NAND_DEV0_ECC_CFG bits */
#define	ECC_CFG_ECC_DISABLE		0
#define	ECC_SW_RESET			1
#define	ECC_MODE			4
#define	ECC_PARITY_SIZE_BYTES_BCH	8
#define	ECC_NUM_DATA_BYTES		16
#define	ECC_FORCE_CLK_OPEN		30

/* NAND_DEV_CMD1 bits */
#define	READ_ADDR			0

/* NAND_DEV_CMD_VLD bits */
#define	READ_START_VLD			0

/* NAND_EBI2_ECC_BUF_CFG bits */
#define	NUM_STEPS			0

/* NAND_ERASED_CW_DETECT_CFG bits */
#define	ERASED_CW_ECC_MASK		1
#define	AUTO_DETECT_RES			0
#define	MASK_ECC			(1 << ERASED_CW_ECC_MASK)
#define	RESET_ERASED_DET		(1 << AUTO_DETECT_RES)
#define	ACTIVE_ERASED_DET		(0 << AUTO_DETECT_RES)
#define	CLR_ERASED_PAGE_DET		(RESET_ERASED_DET | MASK_ECC)
#define	SET_ERASED_PAGE_DET		(ACTIVE_ERASED_DET | MASK_ECC)

/* NAND_ERASED_CW_DETECT_STATUS bits */
#define	PAGE_ALL_ERASED			BIT(7)
#define	CODEWORD_ALL_ERASED		BIT(6)
#define	PAGE_ERASED			BIT(5)
#define	CODEWORD_ERASED			BIT(4)
#define	ERASED_PAGE			(PAGE_ALL_ERASED | PAGE_ERASED)
#define	ERASED_CW			(CODEWORD_ALL_ERASED | CODEWORD_ERASED)

/* Version Mask */
#define	NAND_VERSION_MAJOR_MASK		0xf0000000
#define	NAND_VERSION_MAJOR_SHIFT	28
#define	NAND_VERSION_MINOR_MASK		0x0fff0000
#define	NAND_VERSION_MINOR_SHIFT	16

/* NAND OP_CMDs */
#define	PAGE_READ			0x2
#define	PAGE_READ_WITH_ECC		0x3
#define	PAGE_READ_WITH_ECC_SPARE	0x4
#define	PROGRAM_PAGE			0x6
#define	PAGE_PROGRAM_WITH_ECC		0x7
#define	PROGRAM_PAGE_SPARE		0x9
#define	BLOCK_ERASE			0xa
#define	FETCH_ID			0xb
#define	RESET_DEVICE			0xd

/*
 * the NAND controller performs reads/writes with ECC in 516 byte chunks.
 * the driver calls the chunks 'step' or 'codeword' interchangeably
 */
#define	NANDC_STEP_SIZE			512

/*
 * the largest page size we support is 8K, this will have 16 steps/codewords
 * of 512 bytes each
 */
#define	MAX_NUM_STEPS			(SZ_8K / NANDC_STEP_SIZE)

/* we read at most 3 registers per codeword scan */
#define	MAX_REG_RD			(3 * MAX_NUM_STEPS)

/* ECC modes supported by the controller */
#define	ECC_NONE	BIT(0)
#define	ECC_RS_4BIT	BIT(1)
#define	ECC_BCH_4BIT	BIT(2)
#define	ECC_BCH_8BIT	BIT(3)

struct desc_info {
	struct list_head node;

	enum dma_data_direction dir;
	struct scatterlist sgl;
	struct dma_async_tx_descriptor *dma_desc;
};

/*
 * holds the current register values that we want to write. acts as a contiguous
 * chunk of memory which we use to write the controller registers through DMA.
 */
struct nandc_regs {
	__le32 cmd;
	__le32 addr0;
	__le32 addr1;
	__le32 chip_sel;
	__le32 exec;

	__le32 cfg0;
	__le32 cfg1;
	__le32 ecc_bch_cfg;

	__le32 clrflashstatus;
	__le32 clrreadstatus;

	__le32 cmd1;
	__le32 vld;

	__le32 orig_cmd1;
	__le32 orig_vld;

	__le32 ecc_buf_cfg;
};

/*
 * NAND controller data struct
 *
 * @controller:			base controller structure
 * @host_list:			list containing all the chips attached to the
 *				controller
 * @dev:			parent device
 * @base:			MMIO base
 * @base_dma:			physical base address of controller registers
 * @core_clk:			controller clock
 * @aon_clk:			another controller clock
 *
 * @chan:			dma channel
 * @cmd_crci:			ADM DMA CRCI for command flow control
 * @data_crci:			ADM DMA CRCI for data flow control
 * @desc_list:			DMA descriptor list (list of desc_infos)
 *
 * @data_buffer:		our local DMA buffer for page read/writes,
 *				used when we can't use the buffer provided
 *				by upper layers directly
 * @buf_size/count/start:	markers for chip->read_buf/write_buf functions
 * @reg_read_buf:		local buffer for reading back registers via DMA
 * @reg_read_pos:		marker for data read in reg_read_buf
 *
 * @regs:			a contiguous chunk of memory for DMA register
 *				writes. contains the register values to be
 *				written to controller
 * @cmd1/vld:			some fixed controller register values
 * @ecc_modes:			supported ECC modes by the current controller,
 *				initialized via DT match data
 */
struct qcom_nand_controller {
	struct nand_hw_control controller;
	struct list_head host_list;

	struct device *dev;

	void __iomem *base;
	dma_addr_t base_dma;

	struct clk *core_clk;
	struct clk *aon_clk;

	struct dma_chan *chan;
	unsigned int cmd_crci;
	unsigned int data_crci;
	struct list_head desc_list;

	u8		*data_buffer;
	int		buf_size;
	int		buf_count;
	int		buf_start;

	__le32 *reg_read_buf;
	int reg_read_pos;

	struct nandc_regs *regs;

	u32 cmd1, vld;
	u32 ecc_modes;
};

/*
 * NAND chip structure
 *
 * @chip:			base NAND chip structure
 * @node:			list node to add itself to host_list in
 *				qcom_nand_controller
 *
 * @cs:				chip select value for this chip
 * @cw_size:			the number of bytes in a single step/codeword
 *				of a page, consisting of all data, ecc, spare
 *				and reserved bytes
 * @cw_data:			the number of bytes within a codeword protected
 *				by ECC
 * @use_ecc:			request the controller to use ECC for the
 *				upcoming read/write
 * @bch_enabled:		flag to tell whether BCH ECC mode is used
 * @ecc_bytes_hw:		ECC bytes used by controller hardware for this
 *				chip
 * @status:			value to be returned if NAND_CMD_STATUS command
 *				is executed
 * @last_command:		keeps track of last command on this chip. used
 *				for reading correct status
 *
 * @cfg0, cfg1, cfg0_raw..:	NANDc register configurations needed for
 *				ecc/non-ecc mode for the current nand flash
 *				device
 */
struct qcom_nand_host {
	struct nand_chip chip;
	struct list_head node;

	int cs;
	int cw_size;
	int cw_data;
	bool use_ecc;
	bool bch_enabled;
	int ecc_bytes_hw;
	int spare_bytes;
	int bbm_size;
	u8 status;
	int last_command;

	u32 cfg0, cfg1;
	u32 cfg0_raw, cfg1_raw;
	u32 ecc_buf_cfg;
	u32 ecc_bch_cfg;
	u32 clrflashstatus;
	u32 clrreadstatus;
};

static inline struct qcom_nand_host *to_qcom_nand_host(struct nand_chip *chip)
{
	return container_of(chip, struct qcom_nand_host, chip);
}

static inline struct qcom_nand_controller *
get_qcom_nand_controller(struct nand_chip *chip)
{
	return container_of(chip->controller, struct qcom_nand_controller,
			    controller);
}

static inline u32 nandc_read(struct qcom_nand_controller *nandc, int offset)
{
	return ioread32(nandc->base + offset);
}

static inline void nandc_write(struct qcom_nand_controller *nandc, int offset,
			       u32 val)
{
	iowrite32(val, nandc->base + offset);
}

static __le32 *offset_to_nandc_reg(struct nandc_regs *regs, int offset)
{
	switch (offset) {
	case NAND_FLASH_CMD:
		return &regs->cmd;
	case NAND_ADDR0:
		return &regs->addr0;
	case NAND_ADDR1:
		return &regs->addr1;
	case NAND_FLASH_CHIP_SELECT:
		return &regs->chip_sel;
	case NAND_EXEC_CMD:
		return &regs->exec;
	case NAND_FLASH_STATUS:
		return &regs->clrflashstatus;
	case NAND_DEV0_CFG0:
		return &regs->cfg0;
	case NAND_DEV0_CFG1:
		return &regs->cfg1;
	case NAND_DEV0_ECC_CFG:
		return &regs->ecc_bch_cfg;
	case NAND_READ_STATUS:
		return &regs->clrreadstatus;
	case NAND_DEV_CMD1:
		return &regs->cmd1;
	case NAND_DEV_CMD1_RESTORE:
		return &regs->orig_cmd1;
	case NAND_DEV_CMD_VLD:
		return &regs->vld;
	case NAND_DEV_CMD_VLD_RESTORE:
		return &regs->orig_vld;
	case NAND_EBI2_ECC_BUF_CFG:
		return &regs->ecc_buf_cfg;
	default:
		return NULL;
	}
}

static void nandc_set_reg(struct qcom_nand_controller *nandc, int offset,
			  u32 val)
{
	struct nandc_regs *regs = nandc->regs;
	__le32 *reg;

	reg = offset_to_nandc_reg(regs, offset);

	if (reg)
		*reg = cpu_to_le32(val);
}

/* helper to configure address register values */
static void set_address(struct qcom_nand_host *host, u16 column, int page)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);

	if (chip->options & NAND_BUSWIDTH_16)
		column >>= 1;

	nandc_set_reg(nandc, NAND_ADDR0, page << 16 | column);
	nandc_set_reg(nandc, NAND_ADDR1, page >> 16 & 0xff);
}

/*
 * update_rw_regs:	set up read/write register values, these will be
 *			written to the NAND controller registers via DMA
 *
 * @num_cw:		number of steps for the read/write operation
 * @read:		read or write operation
 */
static void update_rw_regs(struct qcom_nand_host *host, int num_cw, bool read)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	u32 cmd, cfg0, cfg1, ecc_bch_cfg;

	if (read) {
		if (host->use_ecc)
			cmd = PAGE_READ_WITH_ECC | PAGE_ACC | LAST_PAGE;
		else
			cmd = PAGE_READ | PAGE_ACC | LAST_PAGE;
	} else {
			cmd = PROGRAM_PAGE | PAGE_ACC | LAST_PAGE;
	}

	if (host->use_ecc) {
		cfg0 = (host->cfg0 & ~(7U << CW_PER_PAGE)) |
				(num_cw - 1) << CW_PER_PAGE;

		cfg1 = host->cfg1;
		ecc_bch_cfg = host->ecc_bch_cfg;
	} else {
		cfg0 = (host->cfg0_raw & ~(7U << CW_PER_PAGE)) |
				(num_cw - 1) << CW_PER_PAGE;

		cfg1 = host->cfg1_raw;
		ecc_bch_cfg = 1 << ECC_CFG_ECC_DISABLE;
	}

	nandc_set_reg(nandc, NAND_FLASH_CMD, cmd);
	nandc_set_reg(nandc, NAND_DEV0_CFG0, cfg0);
	nandc_set_reg(nandc, NAND_DEV0_CFG1, cfg1);
	nandc_set_reg(nandc, NAND_DEV0_ECC_CFG, ecc_bch_cfg);
	nandc_set_reg(nandc, NAND_EBI2_ECC_BUF_CFG, host->ecc_buf_cfg);
	nandc_set_reg(nandc, NAND_FLASH_STATUS, host->clrflashstatus);
	nandc_set_reg(nandc, NAND_READ_STATUS, host->clrreadstatus);
	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
}

static int prep_dma_desc(struct qcom_nand_controller *nandc, bool read,
			 int reg_off, const void *vaddr, int size,
			 bool flow_control)
{
	struct desc_info *desc;
	struct dma_async_tx_descriptor *dma_desc;
	struct scatterlist *sgl;
	struct dma_slave_config slave_conf;
	enum dma_transfer_direction dir_eng;
	int ret;

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

	sgl = &desc->sgl;

	sg_init_one(sgl, vaddr, size);

	if (read) {
		dir_eng = DMA_DEV_TO_MEM;
		desc->dir = DMA_FROM_DEVICE;
	} else {
		dir_eng = DMA_MEM_TO_DEV;
		desc->dir = DMA_TO_DEVICE;
	}

	ret = dma_map_sg(nandc->dev, sgl, 1, desc->dir);
	if (ret == 0) {
		ret = -ENOMEM;
		goto err;
	}

	memset(&slave_conf, 0x00, sizeof(slave_conf));

	slave_conf.device_fc = flow_control;
	if (read) {
		slave_conf.src_maxburst = 16;
		slave_conf.src_addr = nandc->base_dma + reg_off;
		slave_conf.slave_id = nandc->data_crci;
	} else {
		slave_conf.dst_maxburst = 16;
		slave_conf.dst_addr = nandc->base_dma + reg_off;
		slave_conf.slave_id = nandc->cmd_crci;
	}

	ret = dmaengine_slave_config(nandc->chan, &slave_conf);
	if (ret) {
		dev_err(nandc->dev, "failed to configure dma channel\n");
		goto err;
	}

	dma_desc = dmaengine_prep_slave_sg(nandc->chan, sgl, 1, dir_eng, 0);
	if (!dma_desc) {
		dev_err(nandc->dev, "failed to prepare desc\n");
		ret = -EINVAL;
		goto err;
	}

	desc->dma_desc = dma_desc;

	list_add_tail(&desc->node, &nandc->desc_list);

	return 0;
err:
	kfree(desc);

	return ret;
}

/*
 * read_reg_dma:	prepares a descriptor to read a given number of
 *			contiguous registers to the reg_read_buf pointer
 *
 * @first:		offset of the first register in the contiguous block
 * @num_regs:		number of registers to read
 */
static int read_reg_dma(struct qcom_nand_controller *nandc, int first,
			int num_regs)
{
	bool flow_control = false;
	void *vaddr;
	int size;

	if (first == NAND_READ_ID || first == NAND_FLASH_STATUS)
		flow_control = true;

	size = num_regs * sizeof(u32);
	vaddr = nandc->reg_read_buf + nandc->reg_read_pos;
	nandc->reg_read_pos += num_regs;

	return prep_dma_desc(nandc, true, first, vaddr, size, flow_control);
}

/*
 * write_reg_dma:	prepares a descriptor to write a given number of
 *			contiguous registers
 *
 * @first:		offset of the first register in the contiguous block
 * @num_regs:		number of registers to write
 */
static int write_reg_dma(struct qcom_nand_controller *nandc, int first,
			 int num_regs)
{
	bool flow_control = false;
	struct nandc_regs *regs = nandc->regs;
	void *vaddr;
	int size;

	vaddr = offset_to_nandc_reg(regs, first);

	if (first == NAND_FLASH_CMD)
		flow_control = true;

	if (first == NAND_DEV_CMD1_RESTORE)
		first = NAND_DEV_CMD1;

	if (first == NAND_DEV_CMD_VLD_RESTORE)
		first = NAND_DEV_CMD_VLD;

	size = num_regs * sizeof(u32);

	return prep_dma_desc(nandc, false, first, vaddr, size, flow_control);
}

/*
 * read_data_dma:	prepares a DMA descriptor to transfer data from the
 *			controller's internal buffer to the buffer 'vaddr'
 *
 * @reg_off:		offset within the controller's data buffer
 * @vaddr:		virtual address of the buffer we want to write to
 * @size:		DMA transaction size in bytes
 */
static int read_data_dma(struct qcom_nand_controller *nandc, int reg_off,
			 const u8 *vaddr, int size)
{
	return prep_dma_desc(nandc, true, reg_off, vaddr, size, false);
}

/*
 * write_data_dma:	prepares a DMA descriptor to transfer data from
 *			'vaddr' to the controller's internal buffer
 *
 * @reg_off:		offset within the controller's data buffer
 * @vaddr:		virtual address of the buffer we want to read from
 * @size:		DMA transaction size in bytes
 */
static int write_data_dma(struct qcom_nand_controller *nandc, int reg_off,
			  const u8 *vaddr, int size)
{
	return prep_dma_desc(nandc, false, reg_off, vaddr, size, false);
}

/*
 * helper to prepare dma descriptors to configure registers needed for reading a
 * codeword/step in a page
 */
static void config_cw_read(struct qcom_nand_controller *nandc)
{
	write_reg_dma(nandc, NAND_FLASH_CMD, 3);
	write_reg_dma(nandc, NAND_DEV0_CFG0, 3);
	write_reg_dma(nandc, NAND_EBI2_ECC_BUF_CFG, 1);

	write_reg_dma(nandc, NAND_EXEC_CMD, 1);

	read_reg_dma(nandc, NAND_FLASH_STATUS, 2);
	read_reg_dma(nandc, NAND_ERASED_CW_DETECT_STATUS, 1);
}

/*
 * helpers to prepare dma descriptors used to configure registers needed for
 * writing a codeword/step in a page
 */
static void config_cw_write_pre(struct qcom_nand_controller *nandc)
{
	write_reg_dma(nandc, NAND_FLASH_CMD, 3);
	write_reg_dma(nandc, NAND_DEV0_CFG0, 3);
	write_reg_dma(nandc, NAND_EBI2_ECC_BUF_CFG, 1);
}

static void config_cw_write_post(struct qcom_nand_controller *nandc)
{
	write_reg_dma(nandc, NAND_EXEC_CMD, 1);

	read_reg_dma(nandc, NAND_FLASH_STATUS, 1);

	write_reg_dma(nandc, NAND_FLASH_STATUS, 1);
	write_reg_dma(nandc, NAND_READ_STATUS, 1);
}

/*
 * the following functions are used within chip->cmdfunc() to perform different
 * NAND_CMD_* commands
 */

/* sets up descriptors for NAND_CMD_PARAM */
static int nandc_param(struct qcom_nand_host *host)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);

	/*
	 * NAND_CMD_PARAM is called before we know much about the FLASH chip
	 * in use. we configure the controller to perform a raw read of 512
	 * bytes to read onfi params
	 */
	nandc_set_reg(nandc, NAND_FLASH_CMD, PAGE_READ | PAGE_ACC | LAST_PAGE);
	nandc_set_reg(nandc, NAND_ADDR0, 0);
	nandc_set_reg(nandc, NAND_ADDR1, 0);
	nandc_set_reg(nandc, NAND_DEV0_CFG0, 0 << CW_PER_PAGE
					| 512 << UD_SIZE_BYTES
					| 5 << NUM_ADDR_CYCLES
					| 0 << SPARE_SIZE_BYTES);
	nandc_set_reg(nandc, NAND_DEV0_CFG1, 7 << NAND_RECOVERY_CYCLES
					| 0 << CS_ACTIVE_BSY
					| 17 << BAD_BLOCK_BYTE_NUM
					| 1 << BAD_BLOCK_IN_SPARE_AREA
					| 2 << WR_RD_BSY_GAP
					| 0 << WIDE_FLASH
					| 1 << DEV0_CFG1_ECC_DISABLE);
	nandc_set_reg(nandc, NAND_EBI2_ECC_BUF_CFG, 1 << ECC_CFG_ECC_DISABLE);

	/* configure CMD1 and VLD for ONFI param probing */
	nandc_set_reg(nandc, NAND_DEV_CMD_VLD,
		      (nandc->vld & ~(1 << READ_START_VLD))
		      | 0 << READ_START_VLD);
	nandc_set_reg(nandc, NAND_DEV_CMD1,
		      (nandc->cmd1 & ~(0xFF << READ_ADDR))
		      | NAND_CMD_PARAM << READ_ADDR);

	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);

	nandc_set_reg(nandc, NAND_DEV_CMD1_RESTORE, nandc->cmd1);
	nandc_set_reg(nandc, NAND_DEV_CMD_VLD_RESTORE, nandc->vld);

	write_reg_dma(nandc, NAND_DEV_CMD_VLD, 1);
	write_reg_dma(nandc, NAND_DEV_CMD1, 1);

	nandc->buf_count = 512;
	memset(nandc->data_buffer, 0xff, nandc->buf_count);

	config_cw_read(nandc);

	read_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer,
		      nandc->buf_count);

	/* restore CMD1 and VLD regs */
	write_reg_dma(nandc, NAND_DEV_CMD1_RESTORE, 1);
	write_reg_dma(nandc, NAND_DEV_CMD_VLD_RESTORE, 1);

	return 0;
}

/* sets up descriptors for NAND_CMD_ERASE1 */
static int erase_block(struct qcom_nand_host *host, int page_addr)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);

	nandc_set_reg(nandc, NAND_FLASH_CMD,
		      BLOCK_ERASE | PAGE_ACC | LAST_PAGE);
	nandc_set_reg(nandc, NAND_ADDR0, page_addr);
	nandc_set_reg(nandc, NAND_ADDR1, 0);
	nandc_set_reg(nandc, NAND_DEV0_CFG0,
		      host->cfg0_raw & ~(7 << CW_PER_PAGE));
	nandc_set_reg(nandc, NAND_DEV0_CFG1, host->cfg1_raw);
	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);
	nandc_set_reg(nandc, NAND_FLASH_STATUS, host->clrflashstatus);
	nandc_set_reg(nandc, NAND_READ_STATUS, host->clrreadstatus);

	write_reg_dma(nandc, NAND_FLASH_CMD, 3);
	write_reg_dma(nandc, NAND_DEV0_CFG0, 2);
	write_reg_dma(nandc, NAND_EXEC_CMD, 1);

	read_reg_dma(nandc, NAND_FLASH_STATUS, 1);

	write_reg_dma(nandc, NAND_FLASH_STATUS, 1);
	write_reg_dma(nandc, NAND_READ_STATUS, 1);

	return 0;
}

/* sets up descriptors for NAND_CMD_READID */
static int read_id(struct qcom_nand_host *host, int column)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);

	if (column == -1)
		return 0;

	nandc_set_reg(nandc, NAND_FLASH_CMD, FETCH_ID);
	nandc_set_reg(nandc, NAND_ADDR0, column);
	nandc_set_reg(nandc, NAND_ADDR1, 0);
	nandc_set_reg(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);
	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);

	write_reg_dma(nandc, NAND_FLASH_CMD, 4);
	write_reg_dma(nandc, NAND_EXEC_CMD, 1);

	read_reg_dma(nandc, NAND_READ_ID, 1);

	return 0;
}

/* sets up descriptors for NAND_CMD_RESET */
static int reset(struct qcom_nand_host *host)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);

	nandc_set_reg(nandc, NAND_FLASH_CMD, RESET_DEVICE);
	nandc_set_reg(nandc, NAND_EXEC_CMD, 1);

	write_reg_dma(nandc, NAND_FLASH_CMD, 1);
	write_reg_dma(nandc, NAND_EXEC_CMD, 1);

	read_reg_dma(nandc, NAND_FLASH_STATUS, 1);

	return 0;
}

/* helpers to submit/free our list of dma descriptors */
static int submit_descs(struct qcom_nand_controller *nandc)
{
	struct desc_info *desc;
	dma_cookie_t cookie = 0;

	list_for_each_entry(desc, &nandc->desc_list, node)
		cookie = dmaengine_submit(desc->dma_desc);

	if (dma_sync_wait(nandc->chan, cookie) != DMA_COMPLETE)
		return -ETIMEDOUT;

	return 0;
}

static void free_descs(struct qcom_nand_controller *nandc)
{
	struct desc_info *desc, *n;

	list_for_each_entry_safe(desc, n, &nandc->desc_list, node) {
		list_del(&desc->node);
		dma_unmap_sg(nandc->dev, &desc->sgl, 1, desc->dir);
		kfree(desc);
	}
}

/* reset the register read buffer for next NAND operation */
static void clear_read_regs(struct qcom_nand_controller *nandc)
{
	nandc->reg_read_pos = 0;
	memset(nandc->reg_read_buf, 0,
	       MAX_REG_RD * sizeof(*nandc->reg_read_buf));
}

static void pre_command(struct qcom_nand_host *host, int command)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);

	nandc->buf_count = 0;
	nandc->buf_start = 0;
	host->use_ecc = false;
	host->last_command = command;

	clear_read_regs(nandc);
}

/*
 * this is called after NAND_CMD_PAGEPROG and NAND_CMD_ERASE1 to set our
 * privately maintained status byte, this status byte can be read after
 * NAND_CMD_STATUS is called
 */
static void parse_erase_write_errors(struct qcom_nand_host *host, int command)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	int num_cw;
	int i;

	num_cw = command == NAND_CMD_PAGEPROG ? ecc->steps : 1;

	for (i = 0; i < num_cw; i++) {
		u32 flash_status = le32_to_cpu(nandc->reg_read_buf[i]);

		if (flash_status & FS_MPU_ERR)
			host->status &= ~NAND_STATUS_WP;

		if (flash_status & FS_OP_ERR || (i == (num_cw - 1) &&
						 (flash_status &
						  FS_DEVICE_STS_ERR)))
			host->status |= NAND_STATUS_FAIL;
	}
}

static void post_command(struct qcom_nand_host *host, int command)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);

	switch (command) {
	case NAND_CMD_READID:
		memcpy(nandc->data_buffer, nandc->reg_read_buf,
		       nandc->buf_count);
		break;
	case NAND_CMD_PAGEPROG:
	case NAND_CMD_ERASE1:
		parse_erase_write_errors(host, command);
		break;
	default:
		break;
	}
}

/*
 * Implements chip->cmdfunc. It's  only used for a limited set of commands.
 * The rest of the commands wouldn't be called by upper layers. For example,
 * NAND_CMD_READOOB would never be called because we have our own versions
 * of read_oob ops for nand_ecc_ctrl.
 */
static void qcom_nandc_command(struct mtd_info *mtd, unsigned int command,
			       int column, int page_addr)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	bool wait = false;
	int ret = 0;

	pre_command(host, command);

	switch (command) {
	case NAND_CMD_RESET:
		ret = reset(host);
		wait = true;
		break;

	case NAND_CMD_READID:
		nandc->buf_count = 4;
		ret = read_id(host, column);
		wait = true;
		break;

	case NAND_CMD_PARAM:
		ret = nandc_param(host);
		wait = true;
		break;

	case NAND_CMD_ERASE1:
		ret = erase_block(host, page_addr);
		wait = true;
		break;

	case NAND_CMD_READ0:
		/* we read the entire page for now */
		WARN_ON(column != 0);

		host->use_ecc = true;
		set_address(host, 0, page_addr);
		update_rw_regs(host, ecc->steps, true);
		break;

	case NAND_CMD_SEQIN:
		WARN_ON(column != 0);
		set_address(host, 0, page_addr);
		break;

	case NAND_CMD_PAGEPROG:
	case NAND_CMD_STATUS:
	case NAND_CMD_NONE:
	default:
		break;
	}

	if (ret) {
		dev_err(nandc->dev, "failure executing command %d\n",
			command);
		free_descs(nandc);
		return;
	}

	if (wait) {
		ret = submit_descs(nandc);
		if (ret)
			dev_err(nandc->dev,
				"failure submitting descs for command %d\n",
				command);
	}

	free_descs(nandc);

	post_command(host, command);
}

/*
 * when using BCH ECC, the HW flags an error in NAND_FLASH_STATUS if it read
 * an erased CW, and reports an erased CW in NAND_ERASED_CW_DETECT_STATUS.
 *
 * when using RS ECC, the HW reports the same erros when reading an erased CW,
 * but it notifies that it is an erased CW by placing special characters at
 * certain offsets in the buffer.
 *
 * verify if the page is erased or not, and fix up the page for RS ECC by
 * replacing the special characters with 0xff.
 */
static bool erased_chunk_check_and_fixup(u8 *data_buf, int data_len)
{
	u8 empty1, empty2;

	/*
	 * an erased page flags an error in NAND_FLASH_STATUS, check if the page
	 * is erased by looking for 0x54s at offsets 3 and 175 from the
	 * beginning of each codeword
	 */

	empty1 = data_buf[3];
	empty2 = data_buf[175];

	/*
	 * if the erased codework markers, if they exist override them with
	 * 0xffs
	 */
	if ((empty1 == 0x54 && empty2 == 0xff) ||
	    (empty1 == 0xff && empty2 == 0x54)) {
		data_buf[3] = 0xff;
		data_buf[175] = 0xff;
	}

	/*
	 * check if the entire chunk contains 0xffs or not. if it doesn't, then
	 * restore the original values at the special offsets
	 */
	if (memchr_inv(data_buf, 0xff, data_len)) {
		data_buf[3] = empty1;
		data_buf[175] = empty2;

		return false;
	}

	return true;
}

struct read_stats {
	__le32 flash;
	__le32 buffer;
	__le32 erased_cw;
};

/*
 * reads back status registers set by the controller to notify page read
 * errors. this is equivalent to what 'ecc->correct()' would do.
 */
static int parse_read_errors(struct qcom_nand_host *host, u8 *data_buf,
			     u8 *oob_buf)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	unsigned int max_bitflips = 0;
	struct read_stats *buf;
	int i;

	buf = (struct read_stats *)nandc->reg_read_buf;

	for (i = 0; i < ecc->steps; i++, buf++) {
		u32 flash, buffer, erased_cw;
		int data_len, oob_len;

		if (i == (ecc->steps - 1)) {
			data_len = ecc->size - ((ecc->steps - 1) << 2);
			oob_len = ecc->steps << 2;
		} else {
			data_len = host->cw_data;
			oob_len = 0;
		}

		flash = le32_to_cpu(buf->flash);
		buffer = le32_to_cpu(buf->buffer);
		erased_cw = le32_to_cpu(buf->erased_cw);

		if (flash & (FS_OP_ERR | FS_MPU_ERR)) {
			bool erased;

			/* ignore erased codeword errors */
			if (host->bch_enabled) {
				erased = (erased_cw & ERASED_CW) == ERASED_CW ?
					 true : false;
			} else {
				erased = erased_chunk_check_and_fixup(data_buf,
								      data_len);
			}

			if (erased) {
				data_buf += data_len;
				if (oob_buf)
					oob_buf += oob_len + ecc->bytes;
				continue;
			}

			if (buffer & BS_UNCORRECTABLE_BIT) {
				int ret, ecclen, extraooblen;
				void *eccbuf;

				eccbuf = oob_buf ? oob_buf + oob_len : NULL;
				ecclen = oob_buf ? host->ecc_bytes_hw : 0;
				extraooblen = oob_buf ? oob_len : 0;

				/*
				 * make sure it isn't an erased page reported
				 * as not-erased by HW because of a few bitflips
				 */
				ret = nand_check_erased_ecc_chunk(data_buf,
					data_len, eccbuf, ecclen, oob_buf,
					extraooblen, ecc->strength);
				if (ret < 0) {
					mtd->ecc_stats.failed++;
				} else {
					mtd->ecc_stats.corrected += ret;
					max_bitflips =
						max_t(unsigned int, max_bitflips, ret);
				}
			}
		} else {
			unsigned int stat;

			stat = buffer & BS_CORRECTABLE_ERR_MSK;
			mtd->ecc_stats.corrected += stat;
			max_bitflips = max(max_bitflips, stat);
		}

		data_buf += data_len;
		if (oob_buf)
			oob_buf += oob_len + ecc->bytes;
	}

	return max_bitflips;
}

/*
 * helper to perform the actual page read operation, used by ecc->read_page(),
 * ecc->read_oob()
 */
static int read_page_ecc(struct qcom_nand_host *host, u8 *data_buf,
			 u8 *oob_buf)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	int i, ret;

	/* queue cmd descs for each codeword */
	for (i = 0; i < ecc->steps; i++) {
		int data_size, oob_size;

		if (i == (ecc->steps - 1)) {
			data_size = ecc->size - ((ecc->steps - 1) << 2);
			oob_size = (ecc->steps << 2) + host->ecc_bytes_hw +
				   host->spare_bytes;
		} else {
			data_size = host->cw_data;
			oob_size = host->ecc_bytes_hw + host->spare_bytes;
		}

		config_cw_read(nandc);

		if (data_buf)
			read_data_dma(nandc, FLASH_BUF_ACC, data_buf,
				      data_size);

		/*
		 * when ecc is enabled, the controller doesn't read the real
		 * or dummy bad block markers in each chunk. To maintain a
		 * consistent layout across RAW and ECC reads, we just
		 * leave the real/dummy BBM offsets empty (i.e, filled with
		 * 0xffs)
		 */
		if (oob_buf) {
			int j;

			for (j = 0; j < host->bbm_size; j++)
				*oob_buf++ = 0xff;

			read_data_dma(nandc, FLASH_BUF_ACC + data_size,
				      oob_buf, oob_size);
		}

		if (data_buf)
			data_buf += data_size;
		if (oob_buf)
			oob_buf += oob_size;
	}

	ret = submit_descs(nandc);
	if (ret)
		dev_err(nandc->dev, "failure to read page/oob\n");

	free_descs(nandc);

	return ret;
}

/*
 * a helper that copies the last step/codeword of a page (containing free oob)
 * into our local buffer
 */
static int copy_last_cw(struct qcom_nand_host *host, int page)
{
	struct nand_chip *chip = &host->chip;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	int size;
	int ret;

	clear_read_regs(nandc);

	size = host->use_ecc ? host->cw_data : host->cw_size;

	/* prepare a clean read buffer */
	memset(nandc->data_buffer, 0xff, size);

	set_address(host, host->cw_size * (ecc->steps - 1), page);
	update_rw_regs(host, 1, true);

	config_cw_read(nandc);

	read_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer, size);

	ret = submit_descs(nandc);
	if (ret)
		dev_err(nandc->dev, "failed to copy last codeword\n");

	free_descs(nandc);

	return ret;
}

/* implements ecc->read_page() */
static int qcom_nandc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
				uint8_t *buf, int oob_required, int page)
{
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	u8 *data_buf, *oob_buf = NULL;
	int ret;

	data_buf = buf;
	oob_buf = oob_required ? chip->oob_poi : NULL;

	ret = read_page_ecc(host, data_buf, oob_buf);
	if (ret) {
		dev_err(nandc->dev, "failure to read page\n");
		return ret;
	}

	return parse_read_errors(host, data_buf, oob_buf);
}

/* implements ecc->read_page_raw() */
static int qcom_nandc_read_page_raw(struct mtd_info *mtd,
				    struct nand_chip *chip, uint8_t *buf,
				    int oob_required, int page)
{
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	u8 *data_buf, *oob_buf;
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	int i, ret;

	data_buf = buf;
	oob_buf = chip->oob_poi;

	host->use_ecc = false;
	update_rw_regs(host, ecc->steps, true);

	for (i = 0; i < ecc->steps; i++) {
		int data_size1, data_size2, oob_size1, oob_size2;
		int reg_off = FLASH_BUF_ACC;

		data_size1 = mtd->writesize - host->cw_size * (ecc->steps - 1);
		oob_size1 = host->bbm_size;

		if (i == (ecc->steps - 1)) {
			data_size2 = ecc->size - data_size1 -
				     ((ecc->steps - 1) << 2);
			oob_size2 = (ecc->steps << 2) + host->ecc_bytes_hw +
				    host->spare_bytes;
		} else {
			data_size2 = host->cw_data - data_size1;
			oob_size2 = host->ecc_bytes_hw + host->spare_bytes;
		}

		config_cw_read(nandc);

		read_data_dma(nandc, reg_off, data_buf, data_size1);
		reg_off += data_size1;
		data_buf += data_size1;

		read_data_dma(nandc, reg_off, oob_buf, oob_size1);
		reg_off += oob_size1;
		oob_buf += oob_size1;

		read_data_dma(nandc, reg_off, data_buf, data_size2);
		reg_off += data_size2;
		data_buf += data_size2;

		read_data_dma(nandc, reg_off, oob_buf, oob_size2);
		oob_buf += oob_size2;
	}

	ret = submit_descs(nandc);
	if (ret)
		dev_err(nandc->dev, "failure to read raw page\n");

	free_descs(nandc);

	return 0;
}

/* implements ecc->read_oob() */
static int qcom_nandc_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
			       int page)
{
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	int ret;

	clear_read_regs(nandc);

	host->use_ecc = true;
	set_address(host, 0, page);
	update_rw_regs(host, ecc->steps, true);

	ret = read_page_ecc(host, NULL, chip->oob_poi);
	if (ret)
		dev_err(nandc->dev, "failure to read oob\n");

	return ret;
}

/* implements ecc->write_page() */
static int qcom_nandc_write_page(struct mtd_info *mtd, struct nand_chip *chip,
				 const uint8_t *buf, int oob_required, int page)
{
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	u8 *data_buf, *oob_buf;
	int i, ret;

	clear_read_regs(nandc);

	data_buf = (u8 *)buf;
	oob_buf = chip->oob_poi;

	host->use_ecc = true;
	update_rw_regs(host, ecc->steps, false);

	for (i = 0; i < ecc->steps; i++) {
		int data_size, oob_size;

		if (i == (ecc->steps - 1)) {
			data_size = ecc->size - ((ecc->steps - 1) << 2);
			oob_size = (ecc->steps << 2) + host->ecc_bytes_hw +
				   host->spare_bytes;
		} else {
			data_size = host->cw_data;
			oob_size = ecc->bytes;
		}

		config_cw_write_pre(nandc);

		write_data_dma(nandc, FLASH_BUF_ACC, data_buf, data_size);

		/*
		 * when ECC is enabled, we don't really need to write anything
		 * to oob for the first n - 1 codewords since these oob regions
		 * just contain ECC bytes that's written by the controller
		 * itself. For the last codeword, we skip the bbm positions and
		 * write to the free oob area.
		 */
		if (i == (ecc->steps - 1)) {
			oob_buf += host->bbm_size;

			write_data_dma(nandc, FLASH_BUF_ACC + data_size,
				       oob_buf, oob_size);
		}

		config_cw_write_post(nandc);

		data_buf += data_size;
		oob_buf += oob_size;
	}

	ret = submit_descs(nandc);
	if (ret)
		dev_err(nandc->dev, "failure to write page\n");

	free_descs(nandc);

	return ret;
}

/* implements ecc->write_page_raw() */
static int qcom_nandc_write_page_raw(struct mtd_info *mtd,
				     struct nand_chip *chip, const uint8_t *buf,
				     int oob_required, int page)
{
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	u8 *data_buf, *oob_buf;
	int i, ret;

	clear_read_regs(nandc);

	data_buf = (u8 *)buf;
	oob_buf = chip->oob_poi;

	host->use_ecc = false;
	update_rw_regs(host, ecc->steps, false);

	for (i = 0; i < ecc->steps; i++) {
		int data_size1, data_size2, oob_size1, oob_size2;
		int reg_off = FLASH_BUF_ACC;

		data_size1 = mtd->writesize - host->cw_size * (ecc->steps - 1);
		oob_size1 = host->bbm_size;

		if (i == (ecc->steps - 1)) {
			data_size2 = ecc->size - data_size1 -
				     ((ecc->steps - 1) << 2);
			oob_size2 = (ecc->steps << 2) + host->ecc_bytes_hw +
				    host->spare_bytes;
		} else {
			data_size2 = host->cw_data - data_size1;
			oob_size2 = host->ecc_bytes_hw + host->spare_bytes;
		}

		config_cw_write_pre(nandc);

		write_data_dma(nandc, reg_off, data_buf, data_size1);
		reg_off += data_size1;
		data_buf += data_size1;

		write_data_dma(nandc, reg_off, oob_buf, oob_size1);
		reg_off += oob_size1;
		oob_buf += oob_size1;

		write_data_dma(nandc, reg_off, data_buf, data_size2);
		reg_off += data_size2;
		data_buf += data_size2;

		write_data_dma(nandc, reg_off, oob_buf, oob_size2);
		oob_buf += oob_size2;

		config_cw_write_post(nandc);
	}

	ret = submit_descs(nandc);
	if (ret)
		dev_err(nandc->dev, "failure to write raw page\n");

	free_descs(nandc);

	return ret;
}

/*
 * implements ecc->write_oob()
 *
 * the NAND controller cannot write only data or only oob within a codeword,
 * since ecc is calculated for the combined codeword. we first copy the
 * entire contents for the last codeword(data + oob), replace the old oob
 * with the new one in chip->oob_poi, and then write the entire codeword.
 * this read-copy-write operation results in a slight performance loss.
 */
static int qcom_nandc_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
				int page)
{
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	u8 *oob = chip->oob_poi;
	int data_size, oob_size;
	int ret, status = 0;

	host->use_ecc = true;

	ret = copy_last_cw(host, page);
	if (ret)
		return ret;

	clear_read_regs(nandc);

	/* calculate the data and oob size for the last codeword/step */
	data_size = ecc->size - ((ecc->steps - 1) << 2);
	oob_size = mtd->oobavail;

	/* override new oob content to last codeword */
	mtd_ooblayout_get_databytes(mtd, nandc->data_buffer + data_size, oob,
				    0, mtd->oobavail);

	set_address(host, host->cw_size * (ecc->steps - 1), page);
	update_rw_regs(host, 1, false);

	config_cw_write_pre(nandc);
	write_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer,
		       data_size + oob_size);
	config_cw_write_post(nandc);

	ret = submit_descs(nandc);

	free_descs(nandc);

	if (ret) {
		dev_err(nandc->dev, "failure to write oob\n");
		return -EIO;
	}

	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);

	status = chip->waitfunc(mtd, chip);

	return status & NAND_STATUS_FAIL ? -EIO : 0;
}

static int qcom_nandc_block_bad(struct mtd_info *mtd, loff_t ofs)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	int page, ret, bbpos, bad = 0;
	u32 flash_status;

	page = (int)(ofs >> chip->page_shift) & chip->pagemask;

	/*
	 * configure registers for a raw sub page read, the address is set to
	 * the beginning of the last codeword, we don't care about reading ecc
	 * portion of oob. we just want the first few bytes from this codeword
	 * that contains the BBM
	 */
	host->use_ecc = false;

	ret = copy_last_cw(host, page);
	if (ret)
		goto err;

	flash_status = le32_to_cpu(nandc->reg_read_buf[0]);

	if (flash_status & (FS_OP_ERR | FS_MPU_ERR)) {
		dev_warn(nandc->dev, "error when trying to read BBM\n");
		goto err;
	}

	bbpos = mtd->writesize - host->cw_size * (ecc->steps - 1);

	bad = nandc->data_buffer[bbpos] != 0xff;

	if (chip->options & NAND_BUSWIDTH_16)
		bad = bad || (nandc->data_buffer[bbpos + 1] != 0xff);
err:
	return bad;
}

static int qcom_nandc_block_markbad(struct mtd_info *mtd, loff_t ofs)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	int page, ret, status = 0;

	clear_read_regs(nandc);

	/*
	 * to mark the BBM as bad, we flash the entire last codeword with 0s.
	 * we don't care about the rest of the content in the codeword since
	 * we aren't going to use this block again
	 */
	memset(nandc->data_buffer, 0x00, host->cw_size);

	page = (int)(ofs >> chip->page_shift) & chip->pagemask;

	/* prepare write */
	host->use_ecc = false;
	set_address(host, host->cw_size * (ecc->steps - 1), page);
	update_rw_regs(host, 1, false);

	config_cw_write_pre(nandc);
	write_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer, host->cw_size);
	config_cw_write_post(nandc);

	ret = submit_descs(nandc);

	free_descs(nandc);

	if (ret) {
		dev_err(nandc->dev, "failure to update BBM\n");
		return -EIO;
	}

	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);

	status = chip->waitfunc(mtd, chip);

	return status & NAND_STATUS_FAIL ? -EIO : 0;
}

/*
 * the three functions below implement chip->read_byte(), chip->read_buf()
 * and chip->write_buf() respectively. these aren't used for
 * reading/writing page data, they are used for smaller data like reading
 * id, status etc
 */
static uint8_t qcom_nandc_read_byte(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	u8 *buf = nandc->data_buffer;
	u8 ret = 0x0;

	if (host->last_command == NAND_CMD_STATUS) {
		ret = host->status;

		host->status = NAND_STATUS_READY | NAND_STATUS_WP;

		return ret;
	}

	if (nandc->buf_start < nandc->buf_count)
		ret = buf[nandc->buf_start++];

	return ret;
}

static void qcom_nandc_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	int real_len = min_t(size_t, len, nandc->buf_count - nandc->buf_start);

	memcpy(buf, nandc->data_buffer + nandc->buf_start, real_len);
	nandc->buf_start += real_len;
}

static void qcom_nandc_write_buf(struct mtd_info *mtd, const uint8_t *buf,
				 int len)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	int real_len = min_t(size_t, len, nandc->buf_count - nandc->buf_start);

	memcpy(nandc->data_buffer + nandc->buf_start, buf, real_len);

	nandc->buf_start += real_len;
}

/* we support only one external chip for now */
static void qcom_nandc_select_chip(struct mtd_info *mtd, int chipnr)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);

	if (chipnr <= 0)
		return;

	dev_warn(nandc->dev, "invalid chip select\n");
}

/*
 * NAND controller page layout info
 *
 * Layout with ECC enabled:
 *
 * |----------------------|  |---------------------------------|
 * |           xx.......yy|  |             *********xx.......yy|
 * |    DATA   xx..ECC..yy|  |    DATA     **SPARE**xx..ECC..yy|
 * |   (516)   xx.......yy|  |  (516-n*4)  **(n*4)**xx.......yy|
 * |           xx.......yy|  |             *********xx.......yy|
 * |----------------------|  |---------------------------------|
 *     codeword 1,2..n-1                  codeword n
 *  <---(528/532 Bytes)-->    <-------(528/532 Bytes)--------->
 *
 * n = Number of codewords in the page
 * . = ECC bytes
 * * = Spare/free bytes
 * x = Unused byte(s)
 * y = Reserved byte(s)
 *
 * 2K page: n = 4, spare = 16 bytes
 * 4K page: n = 8, spare = 32 bytes
 * 8K page: n = 16, spare = 64 bytes
 *
 * the qcom nand controller operates at a sub page/codeword level. each
 * codeword is 528 and 532 bytes for 4 bit and 8 bit ECC modes respectively.
 * the number of ECC bytes vary based on the ECC strength and the bus width.
 *
 * the first n - 1 codewords contains 516 bytes of user data, the remaining
 * 12/16 bytes consist of ECC and reserved data. The nth codeword contains
 * both user data and spare(oobavail) bytes that sum up to 516 bytes.
 *
 * When we access a page with ECC enabled, the reserved bytes(s) are not
 * accessible at all. When reading, we fill up these unreadable positions
 * with 0xffs. When writing, the controller skips writing the inaccessible
 * bytes.
 *
 * Layout with ECC disabled:
 *
 * |------------------------------|  |---------------------------------------|
 * |         yy          xx.......|  |         bb          *********xx.......|
 * |  DATA1  yy  DATA2   xx..ECC..|  |  DATA1  bb  DATA2   **SPARE**xx..ECC..|
 * | (size1) yy (size2)  xx.......|  | (size1) bb (size2)  **(n*4)**xx.......|
 * |         yy          xx.......|  |         bb          *********xx.......|
 * |------------------------------|  |---------------------------------------|
 *         codeword 1,2..n-1                        codeword n
 *  <-------(528/532 Bytes)------>    <-----------(528/532 Bytes)----------->
 *
 * n = Number of codewords in the page
 * . = ECC bytes
 * * = Spare/free bytes
 * x = Unused byte(s)
 * y = Dummy Bad Bock byte(s)
 * b = Real Bad Block byte(s)
 * size1/size2 = function of codeword size and 'n'
 *
 * when the ECC block is disabled, one reserved byte (or two for 16 bit bus
 * width) is now accessible. For the first n - 1 codewords, these are dummy Bad
 * Block Markers. In the last codeword, this position contains the real BBM
 *
 * In order to have a consistent layout between RAW and ECC modes, we assume
 * the following OOB layout arrangement:
 *
 * |-----------|  |--------------------|
 * |yyxx.......|  |bb*********xx.......|
 * |yyxx..ECC..|  |bb*FREEOOB*xx..ECC..|
 * |yyxx.......|  |bb*********xx.......|
 * |yyxx.......|  |bb*********xx.......|
 * |-----------|  |--------------------|
 *  first n - 1       nth OOB region
 *  OOB regions
 *
 * n = Number of codewords in the page
 * . = ECC bytes
 * * = FREE OOB bytes
 * y = Dummy bad block byte(s) (inaccessible when ECC enabled)
 * x = Unused byte(s)
 * b = Real bad block byte(s) (inaccessible when ECC enabled)
 *
 * This layout is read as is when ECC is disabled. When ECC is enabled, the
 * inaccessible Bad Block byte(s) are ignored when we write to a page/oob,
 * and assumed as 0xffs when we read a page/oob. The ECC, unused and
 * dummy/real bad block bytes are grouped as ecc bytes (i.e, ecc->bytes is
 * the sum of the three).
 */
static int qcom_nand_ooblayout_ecc(struct mtd_info *mtd, int section,
				   struct mtd_oob_region *oobregion)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;

	if (section > 1)
		return -ERANGE;

	if (!section) {
		oobregion->length = (ecc->bytes * (ecc->steps - 1)) +
				    host->bbm_size;
		oobregion->offset = 0;
	} else {
		oobregion->length = host->ecc_bytes_hw + host->spare_bytes;
		oobregion->offset = mtd->oobsize - oobregion->length;
	}

	return 0;
}

static int qcom_nand_ooblayout_free(struct mtd_info *mtd, int section,
				     struct mtd_oob_region *oobregion)
{
	struct nand_chip *chip = mtd_to_nand(mtd);
	struct qcom_nand_host *host = to_qcom_nand_host(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;

	if (section)
		return -ERANGE;

	oobregion->length = ecc->steps * 4;
	oobregion->offset = ((ecc->steps - 1) * ecc->bytes) + host->bbm_size;

	return 0;
}

static const struct mtd_ooblayout_ops qcom_nand_ooblayout_ops = {
	.ecc = qcom_nand_ooblayout_ecc,
	.free = qcom_nand_ooblayout_free,
};

static int qcom_nand_host_setup(struct qcom_nand_host *host)
{
	struct nand_chip *chip = &host->chip;
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
	int cwperpage, bad_block_byte;
	bool wide_bus;
	int ecc_mode = 1;

	/*
	 * the controller requires each step consists of 512 bytes of data.
	 * bail out if DT has populated a wrong step size.
	 */
	if (ecc->size != NANDC_STEP_SIZE) {
		dev_err(nandc->dev, "invalid ecc size\n");
		return -EINVAL;
	}

	wide_bus = chip->options & NAND_BUSWIDTH_16 ? true : false;

	if (ecc->strength >= 8) {
		/* 8 bit ECC defaults to BCH ECC on all platforms */
		host->bch_enabled = true;
		ecc_mode = 1;

		if (wide_bus) {
			host->ecc_bytes_hw = 14;
			host->spare_bytes = 0;
			host->bbm_size = 2;
		} else {
			host->ecc_bytes_hw = 13;
			host->spare_bytes = 2;
			host->bbm_size = 1;
		}
	} else {
		/*
		 * if the controller supports BCH for 4 bit ECC, the controller
		 * uses lesser bytes for ECC. If RS is used, the ECC bytes is
		 * always 10 bytes
		 */
		if (nandc->ecc_modes & ECC_BCH_4BIT) {
			/* BCH */
			host->bch_enabled = true;
			ecc_mode = 0;

			if (wide_bus) {
				host->ecc_bytes_hw = 8;
				host->spare_bytes = 2;
				host->bbm_size = 2;
			} else {
				host->ecc_bytes_hw = 7;
				host->spare_bytes = 4;
				host->bbm_size = 1;
			}
		} else {
			/* RS */
			host->ecc_bytes_hw = 10;

			if (wide_bus) {
				host->spare_bytes = 0;
				host->bbm_size = 2;
			} else {
				host->spare_bytes = 1;
				host->bbm_size = 1;
			}
		}
	}

	/*
	 * we consider ecc->bytes as the sum of all the non-data content in a
	 * step. It gives us a clean representation of the oob area (even if
	 * all the bytes aren't used for ECC).It is always 16 bytes for 8 bit
	 * ECC and 12 bytes for 4 bit ECC
	 */
	ecc->bytes = host->ecc_bytes_hw + host->spare_bytes + host->bbm_size;

	ecc->read_page		= qcom_nandc_read_page;
	ecc->read_page_raw	= qcom_nandc_read_page_raw;
	ecc->read_oob		= qcom_nandc_read_oob;
	ecc->write_page		= qcom_nandc_write_page;
	ecc->write_page_raw	= qcom_nandc_write_page_raw;
	ecc->write_oob		= qcom_nandc_write_oob;

	ecc->mode = NAND_ECC_HW;

	mtd_set_ooblayout(mtd, &qcom_nand_ooblayout_ops);

	cwperpage = mtd->writesize / ecc->size;

	/*
	 * DATA_UD_BYTES varies based on whether the read/write command protects
	 * spare data with ECC too. We protect spare data by default, so we set
	 * it to main + spare data, which are 512 and 4 bytes respectively.
	 */
	host->cw_data = 516;

	/*
	 * total bytes in a step, either 528 bytes for 4 bit ECC, or 532 bytes
	 * for 8 bit ECC
	 */
	host->cw_size = host->cw_data + ecc->bytes;

	if (ecc->bytes * (mtd->writesize / ecc->size) > mtd->oobsize) {
		dev_err(nandc->dev, "ecc data doesn't fit in OOB area\n");
		return -EINVAL;
	}

	bad_block_byte = mtd->writesize - host->cw_size * (cwperpage - 1) + 1;

	host->cfg0 = (cwperpage - 1) << CW_PER_PAGE
				| host->cw_data << UD_SIZE_BYTES
				| 0 << DISABLE_STATUS_AFTER_WRITE
				| 5 << NUM_ADDR_CYCLES
				| host->ecc_bytes_hw << ECC_PARITY_SIZE_BYTES_RS
				| 0 << STATUS_BFR_READ
				| 1 << SET_RD_MODE_AFTER_STATUS
				| host->spare_bytes << SPARE_SIZE_BYTES;

	host->cfg1 = 7 << NAND_RECOVERY_CYCLES
				| 0 <<  CS_ACTIVE_BSY
				| bad_block_byte << BAD_BLOCK_BYTE_NUM
				| 0 << BAD_BLOCK_IN_SPARE_AREA
				| 2 << WR_RD_BSY_GAP
				| wide_bus << WIDE_FLASH
				| host->bch_enabled << ENABLE_BCH_ECC;

	host->cfg0_raw = (cwperpage - 1) << CW_PER_PAGE
				| host->cw_size << UD_SIZE_BYTES
				| 5 << NUM_ADDR_CYCLES
				| 0 << SPARE_SIZE_BYTES;

	host->cfg1_raw = 7 << NAND_RECOVERY_CYCLES
				| 0 << CS_ACTIVE_BSY
				| 17 << BAD_BLOCK_BYTE_NUM
				| 1 << BAD_BLOCK_IN_SPARE_AREA
				| 2 << WR_RD_BSY_GAP
				| wide_bus << WIDE_FLASH
				| 1 << DEV0_CFG1_ECC_DISABLE;

	host->ecc_bch_cfg = host->bch_enabled << ECC_CFG_ECC_DISABLE
				| 0 << ECC_SW_RESET
				| host->cw_data << ECC_NUM_DATA_BYTES
				| 1 << ECC_FORCE_CLK_OPEN
				| ecc_mode << ECC_MODE
				| host->ecc_bytes_hw << ECC_PARITY_SIZE_BYTES_BCH;

	host->ecc_buf_cfg = 0x203 << NUM_STEPS;

	host->clrflashstatus = FS_READY_BSY_N;
	host->clrreadstatus = 0xc0;

	dev_dbg(nandc->dev,
		"cfg0 %x cfg1 %x ecc_buf_cfg %x ecc_bch cfg %x cw_size %d cw_data %d strength %d parity_bytes %d steps %d\n",
		host->cfg0, host->cfg1, host->ecc_buf_cfg, host->ecc_bch_cfg,
		host->cw_size, host->cw_data, ecc->strength, ecc->bytes,
		cwperpage);

	return 0;
}

static int qcom_nandc_alloc(struct qcom_nand_controller *nandc)
{
	int ret;

	ret = dma_set_coherent_mask(nandc->dev, DMA_BIT_MASK(32));
	if (ret) {
		dev_err(nandc->dev, "failed to set DMA mask\n");
		return ret;
	}

	/*
	 * we use the internal buffer for reading ONFI params, reading small
	 * data like ID and status, and preforming read-copy-write operations
	 * when writing to a codeword partially. 532 is the maximum possible
	 * size of a codeword for our nand controller
	 */
	nandc->buf_size = 532;

	nandc->data_buffer = devm_kzalloc(nandc->dev, nandc->buf_size,
					GFP_KERNEL);
	if (!nandc->data_buffer)
		return -ENOMEM;

	nandc->regs = devm_kzalloc(nandc->dev, sizeof(*nandc->regs),
					GFP_KERNEL);
	if (!nandc->regs)
		return -ENOMEM;

	nandc->reg_read_buf = devm_kzalloc(nandc->dev,
				MAX_REG_RD * sizeof(*nandc->reg_read_buf),
				GFP_KERNEL);
	if (!nandc->reg_read_buf)
		return -ENOMEM;

	nandc->chan = dma_request_slave_channel(nandc->dev, "rxtx");
	if (!nandc->chan) {
		dev_err(nandc->dev, "failed to request slave channel\n");
		return -ENODEV;
	}

	INIT_LIST_HEAD(&nandc->desc_list);
	INIT_LIST_HEAD(&nandc->host_list);

	spin_lock_init(&nandc->controller.lock);
	init_waitqueue_head(&nandc->controller.wq);

	return 0;
}

static void qcom_nandc_unalloc(struct qcom_nand_controller *nandc)
{
	dma_release_channel(nandc->chan);
}

/* one time setup of a few nand controller registers */
static int qcom_nandc_setup(struct qcom_nand_controller *nandc)
{
	/* kill onenand */
	nandc_write(nandc, SFLASHC_BURST_CFG, 0);

	/* enable ADM DMA */
	nandc_write(nandc, NAND_FLASH_CHIP_SELECT, DM_EN);

	/* save the original values of these registers */
	nandc->cmd1 = nandc_read(nandc, NAND_DEV_CMD1);
	nandc->vld = nandc_read(nandc, NAND_DEV_CMD_VLD);

	return 0;
}

static int qcom_nand_host_init(struct qcom_nand_controller *nandc,
			       struct qcom_nand_host *host,
			       struct device_node *dn)
{
	struct nand_chip *chip = &host->chip;
	struct mtd_info *mtd = nand_to_mtd(chip);
	struct device *dev = nandc->dev;
	int ret;

	ret = of_property_read_u32(dn, "reg", &host->cs);
	if (ret) {
		dev_err(dev, "can't get chip-select\n");
		return -ENXIO;
	}

	nand_set_flash_node(chip, dn);
	mtd->name = devm_kasprintf(dev, GFP_KERNEL, "qcom_nand.%d", host->cs);
	mtd->owner = THIS_MODULE;
	mtd->dev.parent = dev;

	chip->cmdfunc		= qcom_nandc_command;
	chip->select_chip	= qcom_nandc_select_chip;
	chip->read_byte		= qcom_nandc_read_byte;
	chip->read_buf		= qcom_nandc_read_buf;
	chip->write_buf		= qcom_nandc_write_buf;

	/*
	 * the bad block marker is readable only when we read the last codeword
	 * of a page with ECC disabled. currently, the nand_base and nand_bbt
	 * helpers don't allow us to read BB from a nand chip with ECC
	 * disabled (MTD_OPS_PLACE_OOB is set by default). use the block_bad
	 * and block_markbad helpers until we permanently switch to using
	 * MTD_OPS_RAW for all drivers (with the help of badblockbits)
	 */
	chip->block_bad		= qcom_nandc_block_bad;
	chip->block_markbad	= qcom_nandc_block_markbad;

	chip->controller = &nandc->controller;
	chip->options |= NAND_NO_SUBPAGE_WRITE | NAND_USE_BOUNCE_BUFFER |
			 NAND_SKIP_BBTSCAN;

	/* set up initial status value */
	host->status = NAND_STATUS_READY | NAND_STATUS_WP;

	ret = nand_scan_ident(mtd, 1, NULL);
	if (ret)
		return ret;

	ret = qcom_nand_host_setup(host);
	if (ret)
		return ret;

	ret = nand_scan_tail(mtd);
	if (ret)
		return ret;

	return mtd_device_register(mtd, NULL, 0);
}

/* parse custom DT properties here */
static int qcom_nandc_parse_dt(struct platform_device *pdev)
{
	struct qcom_nand_controller *nandc = platform_get_drvdata(pdev);
	struct device_node *np = nandc->dev->of_node;
	int ret;

	ret = of_property_read_u32(np, "qcom,cmd-crci", &nandc->cmd_crci);
	if (ret) {
		dev_err(nandc->dev, "command CRCI unspecified\n");
		return ret;
	}

	ret = of_property_read_u32(np, "qcom,data-crci", &nandc->data_crci);
	if (ret) {
		dev_err(nandc->dev, "data CRCI unspecified\n");
		return ret;
	}

	return 0;
}

static int qcom_nandc_probe(struct platform_device *pdev)
{
	struct qcom_nand_controller *nandc;
	struct qcom_nand_host *host;
	const void *dev_data;
	struct device *dev = &pdev->dev;
	struct device_node *dn = dev->of_node, *child;
	struct resource *res;
	int ret;

	nandc = devm_kzalloc(&pdev->dev, sizeof(*nandc), GFP_KERNEL);
	if (!nandc)
		return -ENOMEM;

	platform_set_drvdata(pdev, nandc);
	nandc->dev = dev;

	dev_data = of_device_get_match_data(dev);
	if (!dev_data) {
		dev_err(&pdev->dev, "failed to get device data\n");
		return -ENODEV;
	}

	nandc->ecc_modes = (unsigned long)dev_data;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	nandc->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(nandc->base))
		return PTR_ERR(nandc->base);

	nandc->base_dma = phys_to_dma(dev, (phys_addr_t)res->start);

	nandc->core_clk = devm_clk_get(dev, "core");
	if (IS_ERR(nandc->core_clk))
		return PTR_ERR(nandc->core_clk);

	nandc->aon_clk = devm_clk_get(dev, "aon");
	if (IS_ERR(nandc->aon_clk))
		return PTR_ERR(nandc->aon_clk);

	ret = qcom_nandc_parse_dt(pdev);
	if (ret)
		return ret;

	ret = qcom_nandc_alloc(nandc);
	if (ret)
		return ret;

	ret = clk_prepare_enable(nandc->core_clk);
	if (ret)
		goto err_core_clk;

	ret = clk_prepare_enable(nandc->aon_clk);
	if (ret)
		goto err_aon_clk;

	ret = qcom_nandc_setup(nandc);
	if (ret)
		goto err_setup;

	for_each_available_child_of_node(dn, child) {
		if (of_device_is_compatible(child, "qcom,nandcs")) {
			host = devm_kzalloc(dev, sizeof(*host), GFP_KERNEL);
			if (!host) {
				of_node_put(child);
				ret = -ENOMEM;
				goto err_cs_init;
			}

			ret = qcom_nand_host_init(nandc, host, child);
			if (ret) {
				devm_kfree(dev, host);
				continue;
			}

			list_add_tail(&host->node, &nandc->host_list);
		}
	}

	if (list_empty(&nandc->host_list)) {
		ret = -ENODEV;
		goto err_cs_init;
	}

	return 0;

err_cs_init:
	list_for_each_entry(host, &nandc->host_list, node)
		nand_release(nand_to_mtd(&host->chip));
err_setup:
	clk_disable_unprepare(nandc->aon_clk);
err_aon_clk:
	clk_disable_unprepare(nandc->core_clk);
err_core_clk:
	qcom_nandc_unalloc(nandc);

	return ret;
}

static int qcom_nandc_remove(struct platform_device *pdev)
{
	struct qcom_nand_controller *nandc = platform_get_drvdata(pdev);
	struct qcom_nand_host *host;

	list_for_each_entry(host, &nandc->host_list, node)
		nand_release(nand_to_mtd(&host->chip));

	qcom_nandc_unalloc(nandc);

	clk_disable_unprepare(nandc->aon_clk);
	clk_disable_unprepare(nandc->core_clk);

	return 0;
}

#define EBI2_NANDC_ECC_MODES	(ECC_RS_4BIT | ECC_BCH_8BIT)

/*
 * data will hold a struct pointer containing more differences once we support
 * more controller variants
 */
static const struct of_device_id qcom_nandc_of_match[] = {
	{	.compatible = "qcom,ipq806x-nand",
		.data = (void *)EBI2_NANDC_ECC_MODES,
	},
	{}
};
MODULE_DEVICE_TABLE(of, qcom_nandc_of_match);

static struct platform_driver qcom_nandc_driver = {
	.driver = {
		.name = "qcom-nandc",
		.of_match_table = qcom_nandc_of_match,
	},
	.probe   = qcom_nandc_probe,
	.remove  = qcom_nandc_remove,
};
module_platform_driver(qcom_nandc_driver);

MODULE_AUTHOR("Archit Taneja <architt@codeaurora.org>");
MODULE_DESCRIPTION("Qualcomm NAND Controller driver");
MODULE_LICENSE("GPL v2");