summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/mtdcore.c
blob: 6d5c755411de0d63d88969b96f4fa74d25b39145 (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
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Core registration and callback routines for MTD
 * drivers and users.
 *
 * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
 * Copyright © 2006      Red Hat UK Limited 
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/err.h>
#include <linux/ioctl.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/proc_fs.h>
#include <linux/idr.h>
#include <linux/backing-dev.h>
#include <linux/gfp.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/reboot.h>
#include <linux/leds.h>
#include <linux/debugfs.h>
#include <linux/nvmem-provider.h>
#include <linux/root_dev.h>
#include <linux/error-injection.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>

#include "mtdcore.h"

struct backing_dev_info *mtd_bdi;

#ifdef CONFIG_PM_SLEEP

static int mtd_cls_suspend(struct device *dev)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return mtd ? mtd_suspend(mtd) : 0;
}

static int mtd_cls_resume(struct device *dev)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	if (mtd)
		mtd_resume(mtd);
	return 0;
}

static SIMPLE_DEV_PM_OPS(mtd_cls_pm_ops, mtd_cls_suspend, mtd_cls_resume);
#define MTD_CLS_PM_OPS (&mtd_cls_pm_ops)
#else
#define MTD_CLS_PM_OPS NULL
#endif

static struct class mtd_class = {
	.name = "mtd",
	.pm = MTD_CLS_PM_OPS,
};

static DEFINE_IDR(mtd_idr);

/* These are exported solely for the purpose of mtd_blkdevs.c. You
   should not use them for _anything_ else */
DEFINE_MUTEX(mtd_table_mutex);
EXPORT_SYMBOL_GPL(mtd_table_mutex);

struct mtd_info *__mtd_next_device(int i)
{
	return idr_get_next(&mtd_idr, &i);
}
EXPORT_SYMBOL_GPL(__mtd_next_device);

static LIST_HEAD(mtd_notifiers);


#define MTD_DEVT(index) MKDEV(MTD_CHAR_MAJOR, (index)*2)

/* REVISIT once MTD uses the driver model better, whoever allocates
 * the mtd_info will probably want to use the release() hook...
 */
static void mtd_release(struct device *dev)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	dev_t index = MTD_DEVT(mtd->index);

	idr_remove(&mtd_idr, mtd->index);
	of_node_put(mtd_get_of_node(mtd));

	if (mtd_is_partition(mtd))
		release_mtd_partition(mtd);

	/* remove /dev/mtdXro node */
	device_destroy(&mtd_class, index + 1);
}

static void mtd_device_release(struct kref *kref)
{
	struct mtd_info *mtd = container_of(kref, struct mtd_info, refcnt);
	bool is_partition = mtd_is_partition(mtd);

	debugfs_remove_recursive(mtd->dbg.dfs_dir);

	/* Try to remove the NVMEM provider */
	nvmem_unregister(mtd->nvmem);

	device_unregister(&mtd->dev);

	/*
	 *  Clear dev so mtd can be safely re-registered later if desired.
	 *  Should not be done for partition,
	 *  as it was already destroyed in device_unregister().
	 */
	if (!is_partition)
		memset(&mtd->dev, 0, sizeof(mtd->dev));

	module_put(THIS_MODULE);
}

#define MTD_DEVICE_ATTR_RO(name) \
static DEVICE_ATTR(name, 0444, mtd_##name##_show, NULL)

#define MTD_DEVICE_ATTR_RW(name) \
static DEVICE_ATTR(name, 0644, mtd_##name##_show, mtd_##name##_store)

static ssize_t mtd_type_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	char *type;

	switch (mtd->type) {
	case MTD_ABSENT:
		type = "absent";
		break;
	case MTD_RAM:
		type = "ram";
		break;
	case MTD_ROM:
		type = "rom";
		break;
	case MTD_NORFLASH:
		type = "nor";
		break;
	case MTD_NANDFLASH:
		type = "nand";
		break;
	case MTD_DATAFLASH:
		type = "dataflash";
		break;
	case MTD_UBIVOLUME:
		type = "ubi";
		break;
	case MTD_MLCNANDFLASH:
		type = "mlc-nand";
		break;
	default:
		type = "unknown";
	}

	return sysfs_emit(buf, "%s\n", type);
}
MTD_DEVICE_ATTR_RO(type);

static ssize_t mtd_flags_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "0x%lx\n", (unsigned long)mtd->flags);
}
MTD_DEVICE_ATTR_RO(flags);

static ssize_t mtd_size_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%llu\n", (unsigned long long)mtd->size);
}
MTD_DEVICE_ATTR_RO(size);

static ssize_t mtd_erasesize_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%lu\n", (unsigned long)mtd->erasesize);
}
MTD_DEVICE_ATTR_RO(erasesize);

static ssize_t mtd_writesize_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%lu\n", (unsigned long)mtd->writesize);
}
MTD_DEVICE_ATTR_RO(writesize);

static ssize_t mtd_subpagesize_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	unsigned int subpagesize = mtd->writesize >> mtd->subpage_sft;

	return sysfs_emit(buf, "%u\n", subpagesize);
}
MTD_DEVICE_ATTR_RO(subpagesize);

static ssize_t mtd_oobsize_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%lu\n", (unsigned long)mtd->oobsize);
}
MTD_DEVICE_ATTR_RO(oobsize);

static ssize_t mtd_oobavail_show(struct device *dev,
				 struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%u\n", mtd->oobavail);
}
MTD_DEVICE_ATTR_RO(oobavail);

static ssize_t mtd_numeraseregions_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%u\n", mtd->numeraseregions);
}
MTD_DEVICE_ATTR_RO(numeraseregions);

static ssize_t mtd_name_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%s\n", mtd->name);
}
MTD_DEVICE_ATTR_RO(name);

static ssize_t mtd_ecc_strength_show(struct device *dev,
				     struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%u\n", mtd->ecc_strength);
}
MTD_DEVICE_ATTR_RO(ecc_strength);

static ssize_t mtd_bitflip_threshold_show(struct device *dev,
					  struct device_attribute *attr,
					  char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%u\n", mtd->bitflip_threshold);
}

static ssize_t mtd_bitflip_threshold_store(struct device *dev,
					   struct device_attribute *attr,
					   const char *buf, size_t count)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	unsigned int bitflip_threshold;
	int retval;

	retval = kstrtouint(buf, 0, &bitflip_threshold);
	if (retval)
		return retval;

	mtd->bitflip_threshold = bitflip_threshold;
	return count;
}
MTD_DEVICE_ATTR_RW(bitflip_threshold);

static ssize_t mtd_ecc_step_size_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%u\n", mtd->ecc_step_size);

}
MTD_DEVICE_ATTR_RO(ecc_step_size);

static ssize_t mtd_corrected_bits_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	struct mtd_ecc_stats *ecc_stats = &mtd->ecc_stats;

	return sysfs_emit(buf, "%u\n", ecc_stats->corrected);
}
MTD_DEVICE_ATTR_RO(corrected_bits);	/* ecc stats corrected */

static ssize_t mtd_ecc_failures_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	struct mtd_ecc_stats *ecc_stats = &mtd->ecc_stats;

	return sysfs_emit(buf, "%u\n", ecc_stats->failed);
}
MTD_DEVICE_ATTR_RO(ecc_failures);	/* ecc stats errors */

static ssize_t mtd_bad_blocks_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	struct mtd_ecc_stats *ecc_stats = &mtd->ecc_stats;

	return sysfs_emit(buf, "%u\n", ecc_stats->badblocks);
}
MTD_DEVICE_ATTR_RO(bad_blocks);

static ssize_t mtd_bbt_blocks_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	struct mtd_ecc_stats *ecc_stats = &mtd->ecc_stats;

	return sysfs_emit(buf, "%u\n", ecc_stats->bbtblocks);
}
MTD_DEVICE_ATTR_RO(bbt_blocks);

static struct attribute *mtd_attrs[] = {
	&dev_attr_type.attr,
	&dev_attr_flags.attr,
	&dev_attr_size.attr,
	&dev_attr_erasesize.attr,
	&dev_attr_writesize.attr,
	&dev_attr_subpagesize.attr,
	&dev_attr_oobsize.attr,
	&dev_attr_oobavail.attr,
	&dev_attr_numeraseregions.attr,
	&dev_attr_name.attr,
	&dev_attr_ecc_strength.attr,
	&dev_attr_ecc_step_size.attr,
	&dev_attr_corrected_bits.attr,
	&dev_attr_ecc_failures.attr,
	&dev_attr_bad_blocks.attr,
	&dev_attr_bbt_blocks.attr,
	&dev_attr_bitflip_threshold.attr,
	NULL,
};
ATTRIBUTE_GROUPS(mtd);

static const struct device_type mtd_devtype = {
	.name		= "mtd",
	.groups		= mtd_groups,
	.release	= mtd_release,
};

static bool mtd_expert_analysis_mode;

#ifdef CONFIG_DEBUG_FS
bool mtd_check_expert_analysis_mode(void)
{
	const char *mtd_expert_analysis_warning =
		"Bad block checks have been entirely disabled.\n"
		"This is only reserved for post-mortem forensics and debug purposes.\n"
		"Never enable this mode if you do not know what you are doing!\n";

	return WARN_ONCE(mtd_expert_analysis_mode, mtd_expert_analysis_warning);
}
EXPORT_SYMBOL_GPL(mtd_check_expert_analysis_mode);
#endif

static struct dentry *dfs_dir_mtd;

static void mtd_debugfs_populate(struct mtd_info *mtd)
{
	struct device *dev = &mtd->dev;

	if (IS_ERR_OR_NULL(dfs_dir_mtd))
		return;

	mtd->dbg.dfs_dir = debugfs_create_dir(dev_name(dev), dfs_dir_mtd);
}

#ifndef CONFIG_MMU
unsigned mtd_mmap_capabilities(struct mtd_info *mtd)
{
	switch (mtd->type) {
	case MTD_RAM:
		return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | NOMMU_MAP_EXEC |
			NOMMU_MAP_READ | NOMMU_MAP_WRITE;
	case MTD_ROM:
		return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | NOMMU_MAP_EXEC |
			NOMMU_MAP_READ;
	default:
		return NOMMU_MAP_COPY;
	}
}
EXPORT_SYMBOL_GPL(mtd_mmap_capabilities);
#endif

static int mtd_reboot_notifier(struct notifier_block *n, unsigned long state,
			       void *cmd)
{
	struct mtd_info *mtd;

	mtd = container_of(n, struct mtd_info, reboot_notifier);
	mtd->_reboot(mtd);

	return NOTIFY_DONE;
}

/**
 * mtd_wunit_to_pairing_info - get pairing information of a wunit
 * @mtd: pointer to new MTD device info structure
 * @wunit: write unit we are interested in
 * @info: returned pairing information
 *
 * Retrieve pairing information associated to the wunit.
 * This is mainly useful when dealing with MLC/TLC NANDs where pages can be
 * paired together, and where programming a page may influence the page it is
 * paired with.
 * The notion of page is replaced by the term wunit (write-unit) to stay
 * consistent with the ->writesize field.
 *
 * The @wunit argument can be extracted from an absolute offset using
 * mtd_offset_to_wunit(). @info is filled with the pairing information attached
 * to @wunit.
 *
 * From the pairing info the MTD user can find all the wunits paired with
 * @wunit using the following loop:
 *
 * for (i = 0; i < mtd_pairing_groups(mtd); i++) {
 *	info.pair = i;
 *	mtd_pairing_info_to_wunit(mtd, &info);
 *	...
 * }
 */
int mtd_wunit_to_pairing_info(struct mtd_info *mtd, int wunit,
			      struct mtd_pairing_info *info)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int npairs = mtd_wunit_per_eb(master) / mtd_pairing_groups(master);

	if (wunit < 0 || wunit >= npairs)
		return -EINVAL;

	if (master->pairing && master->pairing->get_info)
		return master->pairing->get_info(master, wunit, info);

	info->group = 0;
	info->pair = wunit;

	return 0;
}
EXPORT_SYMBOL_GPL(mtd_wunit_to_pairing_info);

/**
 * mtd_pairing_info_to_wunit - get wunit from pairing information
 * @mtd: pointer to new MTD device info structure
 * @info: pairing information struct
 *
 * Returns a positive number representing the wunit associated to the info
 * struct, or a negative error code.
 *
 * This is the reverse of mtd_wunit_to_pairing_info(), and can help one to
 * iterate over all wunits of a given pair (see mtd_wunit_to_pairing_info()
 * doc).
 *
 * It can also be used to only program the first page of each pair (i.e.
 * page attached to group 0), which allows one to use an MLC NAND in
 * software-emulated SLC mode:
 *
 * info.group = 0;
 * npairs = mtd_wunit_per_eb(mtd) / mtd_pairing_groups(mtd);
 * for (info.pair = 0; info.pair < npairs; info.pair++) {
 *	wunit = mtd_pairing_info_to_wunit(mtd, &info);
 *	mtd_write(mtd, mtd_wunit_to_offset(mtd, blkoffs, wunit),
 *		  mtd->writesize, &retlen, buf + (i * mtd->writesize));
 * }
 */
int mtd_pairing_info_to_wunit(struct mtd_info *mtd,
			      const struct mtd_pairing_info *info)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int ngroups = mtd_pairing_groups(master);
	int npairs = mtd_wunit_per_eb(master) / ngroups;

	if (!info || info->pair < 0 || info->pair >= npairs ||
	    info->group < 0 || info->group >= ngroups)
		return -EINVAL;

	if (master->pairing && master->pairing->get_wunit)
		return mtd->pairing->get_wunit(master, info);

	return info->pair;
}
EXPORT_SYMBOL_GPL(mtd_pairing_info_to_wunit);

/**
 * mtd_pairing_groups - get the number of pairing groups
 * @mtd: pointer to new MTD device info structure
 *
 * Returns the number of pairing groups.
 *
 * This number is usually equal to the number of bits exposed by a single
 * cell, and can be used in conjunction with mtd_pairing_info_to_wunit()
 * to iterate over all pages of a given pair.
 */
int mtd_pairing_groups(struct mtd_info *mtd)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->pairing || !master->pairing->ngroups)
		return 1;

	return master->pairing->ngroups;
}
EXPORT_SYMBOL_GPL(mtd_pairing_groups);

static int mtd_nvmem_reg_read(void *priv, unsigned int offset,
			      void *val, size_t bytes)
{
	struct mtd_info *mtd = priv;
	size_t retlen;
	int err;

	err = mtd_read(mtd, offset, bytes, &retlen, val);
	if (err && err != -EUCLEAN)
		return err;

	return retlen == bytes ? 0 : -EIO;
}

static int mtd_nvmem_add(struct mtd_info *mtd)
{
	struct device_node *node = mtd_get_of_node(mtd);
	struct nvmem_config config = {};

	config.id = NVMEM_DEVID_NONE;
	config.dev = &mtd->dev;
	config.name = dev_name(&mtd->dev);
	config.owner = THIS_MODULE;
	config.add_legacy_fixed_of_cells = of_device_is_compatible(node, "nvmem-cells");
	config.reg_read = mtd_nvmem_reg_read;
	config.size = mtd->size;
	config.word_size = 1;
	config.stride = 1;
	config.read_only = true;
	config.root_only = true;
	config.ignore_wp = true;
	config.priv = mtd;

	mtd->nvmem = nvmem_register(&config);
	if (IS_ERR(mtd->nvmem)) {
		/* Just ignore if there is no NVMEM support in the kernel */
		if (PTR_ERR(mtd->nvmem) == -EOPNOTSUPP)
			mtd->nvmem = NULL;
		else
			return dev_err_probe(&mtd->dev, PTR_ERR(mtd->nvmem),
					     "Failed to register NVMEM device\n");
	}

	return 0;
}

static void mtd_check_of_node(struct mtd_info *mtd)
{
	struct device_node *partitions, *parent_dn, *mtd_dn = NULL;
	const char *pname, *prefix = "partition-";
	int plen, mtd_name_len, offset, prefix_len;

	/* Check if MTD already has a device node */
	if (mtd_get_of_node(mtd))
		return;

	if (!mtd_is_partition(mtd))
		return;

	parent_dn = of_node_get(mtd_get_of_node(mtd->parent));
	if (!parent_dn)
		return;

	if (mtd_is_partition(mtd->parent))
		partitions = of_node_get(parent_dn);
	else
		partitions = of_get_child_by_name(parent_dn, "partitions");
	if (!partitions)
		goto exit_parent;

	prefix_len = strlen(prefix);
	mtd_name_len = strlen(mtd->name);

	/* Search if a partition is defined with the same name */
	for_each_child_of_node(partitions, mtd_dn) {
		/* Skip partition with no/wrong prefix */
		if (!of_node_name_prefix(mtd_dn, prefix))
			continue;

		/* Label have priority. Check that first */
		if (!of_property_read_string(mtd_dn, "label", &pname)) {
			offset = 0;
		} else {
			pname = mtd_dn->name;
			offset = prefix_len;
		}

		plen = strlen(pname) - offset;
		if (plen == mtd_name_len &&
		    !strncmp(mtd->name, pname + offset, plen)) {
			mtd_set_of_node(mtd, mtd_dn);
			of_node_put(mtd_dn);
			break;
		}
	}

	of_node_put(partitions);
exit_parent:
	of_node_put(parent_dn);
}

/**
 *	add_mtd_device - register an MTD device
 *	@mtd: pointer to new MTD device info structure
 *
 *	Add a device to the list of MTD devices present in the system, and
 *	notify each currently active MTD 'user' of its arrival. Returns
 *	zero on success or non-zero on failure.
 */

int add_mtd_device(struct mtd_info *mtd)
{
	struct device_node *np = mtd_get_of_node(mtd);
	struct mtd_info *master = mtd_get_master(mtd);
	struct mtd_notifier *not;
	int i, error, ofidx;

	/*
	 * May occur, for instance, on buggy drivers which call
	 * mtd_device_parse_register() multiple times on the same master MTD,
	 * especially with CONFIG_MTD_PARTITIONED_MASTER=y.
	 */
	if (WARN_ONCE(mtd->dev.type, "MTD already registered\n"))
		return -EEXIST;

	BUG_ON(mtd->writesize == 0);

	/*
	 * MTD drivers should implement ->_{write,read}() or
	 * ->_{write,read}_oob(), but not both.
	 */
	if (WARN_ON((mtd->_write && mtd->_write_oob) ||
		    (mtd->_read && mtd->_read_oob)))
		return -EINVAL;

	if (WARN_ON((!mtd->erasesize || !master->_erase) &&
		    !(mtd->flags & MTD_NO_ERASE)))
		return -EINVAL;

	/*
	 * MTD_SLC_ON_MLC_EMULATION can only be set on partitions, when the
	 * master is an MLC NAND and has a proper pairing scheme defined.
	 * We also reject masters that implement ->_writev() for now, because
	 * NAND controller drivers don't implement this hook, and adding the
	 * SLC -> MLC address/length conversion to this path is useless if we
	 * don't have a user.
	 */
	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION &&
	    (!mtd_is_partition(mtd) || master->type != MTD_MLCNANDFLASH ||
	     !master->pairing || master->_writev))
		return -EINVAL;

	mutex_lock(&mtd_table_mutex);

	ofidx = -1;
	if (np)
		ofidx = of_alias_get_id(np, "mtd");
	if (ofidx >= 0)
		i = idr_alloc(&mtd_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
	else
		i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
	if (i < 0) {
		error = i;
		goto fail_locked;
	}

	mtd->index = i;
	kref_init(&mtd->refcnt);

	/* default value if not set by driver */
	if (mtd->bitflip_threshold == 0)
		mtd->bitflip_threshold = mtd->ecc_strength;

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
		int ngroups = mtd_pairing_groups(master);

		mtd->erasesize /= ngroups;
		mtd->size = (u64)mtd_div_by_eb(mtd->size, master) *
			    mtd->erasesize;
	}

	if (is_power_of_2(mtd->erasesize))
		mtd->erasesize_shift = ffs(mtd->erasesize) - 1;
	else
		mtd->erasesize_shift = 0;

	if (is_power_of_2(mtd->writesize))
		mtd->writesize_shift = ffs(mtd->writesize) - 1;
	else
		mtd->writesize_shift = 0;

	mtd->erasesize_mask = (1 << mtd->erasesize_shift) - 1;
	mtd->writesize_mask = (1 << mtd->writesize_shift) - 1;

	/* Some chips always power up locked. Unlock them now */
	if ((mtd->flags & MTD_WRITEABLE) && (mtd->flags & MTD_POWERUP_LOCK)) {
		error = mtd_unlock(mtd, 0, mtd->size);
		if (error && error != -EOPNOTSUPP)
			printk(KERN_WARNING
			       "%s: unlock failed, writes may not work\n",
			       mtd->name);
		/* Ignore unlock failures? */
		error = 0;
	}

	/* Caller should have set dev.parent to match the
	 * physical device, if appropriate.
	 */
	mtd->dev.type = &mtd_devtype;
	mtd->dev.class = &mtd_class;
	mtd->dev.devt = MTD_DEVT(i);
	dev_set_name(&mtd->dev, "mtd%d", i);
	dev_set_drvdata(&mtd->dev, mtd);
	mtd_check_of_node(mtd);
	of_node_get(mtd_get_of_node(mtd));
	error = device_register(&mtd->dev);
	if (error) {
		put_device(&mtd->dev);
		goto fail_added;
	}

	/* Add the nvmem provider */
	error = mtd_nvmem_add(mtd);
	if (error)
		goto fail_nvmem_add;

	mtd_debugfs_populate(mtd);

	device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, NULL,
		      "mtd%dro", i);

	pr_debug("mtd: Giving out device %d to %s\n", i, mtd->name);
	/* No need to get a refcount on the module containing
	   the notifier, since we hold the mtd_table_mutex */
	list_for_each_entry(not, &mtd_notifiers, list)
		not->add(mtd);

	mutex_unlock(&mtd_table_mutex);

	if (of_property_read_bool(mtd_get_of_node(mtd), "linux,rootfs")) {
		if (IS_BUILTIN(CONFIG_MTD)) {
			pr_info("mtd: setting mtd%d (%s) as root device\n", mtd->index, mtd->name);
			ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
		} else {
			pr_warn("mtd: can't set mtd%d (%s) as root device - mtd must be builtin\n",
				mtd->index, mtd->name);
		}
	}

	/* We _know_ we aren't being removed, because
	   our caller is still holding us here. So none
	   of this try_ nonsense, and no bitching about it
	   either. :) */
	__module_get(THIS_MODULE);
	return 0;

fail_nvmem_add:
	device_unregister(&mtd->dev);
fail_added:
	of_node_put(mtd_get_of_node(mtd));
	idr_remove(&mtd_idr, i);
fail_locked:
	mutex_unlock(&mtd_table_mutex);
	return error;
}

/**
 *	del_mtd_device - unregister an MTD device
 *	@mtd: pointer to MTD device info structure
 *
 *	Remove a device from the list of MTD devices present in the system,
 *	and notify each currently active MTD 'user' of its departure.
 *	Returns zero on success or 1 on failure, which currently will happen
 *	if the requested device does not appear to be present in the list.
 */

int del_mtd_device(struct mtd_info *mtd)
{
	int ret;
	struct mtd_notifier *not;

	mutex_lock(&mtd_table_mutex);

	if (idr_find(&mtd_idr, mtd->index) != mtd) {
		ret = -ENODEV;
		goto out_error;
	}

	/* No need to get a refcount on the module containing
		the notifier, since we hold the mtd_table_mutex */
	list_for_each_entry(not, &mtd_notifiers, list)
		not->remove(mtd);

	kref_put(&mtd->refcnt, mtd_device_release);
	ret = 0;

out_error:
	mutex_unlock(&mtd_table_mutex);
	return ret;
}

/*
 * Set a few defaults based on the parent devices, if not provided by the
 * driver
 */
static void mtd_set_dev_defaults(struct mtd_info *mtd)
{
	if (mtd->dev.parent) {
		if (!mtd->owner && mtd->dev.parent->driver)
			mtd->owner = mtd->dev.parent->driver->owner;
		if (!mtd->name)
			mtd->name = dev_name(mtd->dev.parent);
	} else {
		pr_debug("mtd device won't show a device symlink in sysfs\n");
	}

	INIT_LIST_HEAD(&mtd->partitions);
	mutex_init(&mtd->master.partitions_lock);
	mutex_init(&mtd->master.chrdev_lock);
}

static ssize_t mtd_otp_size(struct mtd_info *mtd, bool is_user)
{
	struct otp_info *info;
	ssize_t size = 0;
	unsigned int i;
	size_t retlen;
	int ret;

	info = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!info)
		return -ENOMEM;

	if (is_user)
		ret = mtd_get_user_prot_info(mtd, PAGE_SIZE, &retlen, info);
	else
		ret = mtd_get_fact_prot_info(mtd, PAGE_SIZE, &retlen, info);
	if (ret)
		goto err;

	for (i = 0; i < retlen / sizeof(*info); i++)
		size += info[i].length;

	kfree(info);
	return size;

err:
	kfree(info);

	/* ENODATA means there is no OTP region. */
	return ret == -ENODATA ? 0 : ret;
}

static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
						   const char *compatible,
						   int size,
						   nvmem_reg_read_t reg_read)
{
	struct nvmem_device *nvmem = NULL;
	struct nvmem_config config = {};
	struct device_node *np;

	/* DT binding is optional */
	np = of_get_compatible_child(mtd->dev.of_node, compatible);

	/* OTP nvmem will be registered on the physical device */
	config.dev = mtd->dev.parent;
	config.name = compatible;
	config.id = NVMEM_DEVID_AUTO;
	config.owner = THIS_MODULE;
	config.add_legacy_fixed_of_cells = !mtd_type_is_nand(mtd);
	config.type = NVMEM_TYPE_OTP;
	config.root_only = true;
	config.ignore_wp = true;
	config.reg_read = reg_read;
	config.size = size;
	config.of_node = np;
	config.priv = mtd;

	nvmem = nvmem_register(&config);
	/* Just ignore if there is no NVMEM support in the kernel */
	if (IS_ERR(nvmem) && PTR_ERR(nvmem) == -EOPNOTSUPP)
		nvmem = NULL;

	of_node_put(np);

	return nvmem;
}

static int mtd_nvmem_user_otp_reg_read(void *priv, unsigned int offset,
				       void *val, size_t bytes)
{
	struct mtd_info *mtd = priv;
	size_t retlen;
	int ret;

	ret = mtd_read_user_prot_reg(mtd, offset, bytes, &retlen, val);
	if (ret)
		return ret;

	return retlen == bytes ? 0 : -EIO;
}

static int mtd_nvmem_fact_otp_reg_read(void *priv, unsigned int offset,
				       void *val, size_t bytes)
{
	struct mtd_info *mtd = priv;
	size_t retlen;
	int ret;

	ret = mtd_read_fact_prot_reg(mtd, offset, bytes, &retlen, val);
	if (ret)
		return ret;

	return retlen == bytes ? 0 : -EIO;
}

static int mtd_otp_nvmem_add(struct mtd_info *mtd)
{
	struct device *dev = mtd->dev.parent;
	struct nvmem_device *nvmem;
	ssize_t size;
	int err;

	if (mtd->_get_user_prot_info && mtd->_read_user_prot_reg) {
		size = mtd_otp_size(mtd, true);
		if (size < 0) {
			err = size;
			goto err;
		}

		if (size > 0) {
			nvmem = mtd_otp_nvmem_register(mtd, "user-otp", size,
						       mtd_nvmem_user_otp_reg_read);
			if (IS_ERR(nvmem)) {
				err = PTR_ERR(nvmem);
				goto err;
			}
			mtd->otp_user_nvmem = nvmem;
		}
	}

	if (mtd->_get_fact_prot_info && mtd->_read_fact_prot_reg) {
		size = mtd_otp_size(mtd, false);
		if (size < 0) {
			err = size;
			goto err;
		}

		if (size > 0) {
			/*
			 * The factory OTP contains thing such as a unique serial
			 * number and is small, so let's read it out and put it
			 * into the entropy pool.
			 */
			void *otp;

			otp = kmalloc(size, GFP_KERNEL);
			if (!otp) {
				err = -ENOMEM;
				goto err;
			}
			err = mtd_nvmem_fact_otp_reg_read(mtd, 0, otp, size);
			if (err < 0) {
				kfree(otp);
				goto err;
			}
			add_device_randomness(otp, err);
			kfree(otp);

			nvmem = mtd_otp_nvmem_register(mtd, "factory-otp", size,
						       mtd_nvmem_fact_otp_reg_read);
			if (IS_ERR(nvmem)) {
				err = PTR_ERR(nvmem);
				goto err;
			}
			mtd->otp_factory_nvmem = nvmem;
		}
	}

	return 0;

err:
	nvmem_unregister(mtd->otp_user_nvmem);
	return dev_err_probe(dev, err, "Failed to register OTP NVMEM device\n");
}

/**
 * mtd_device_parse_register - parse partitions and register an MTD device.
 *
 * @mtd: the MTD device to register
 * @types: the list of MTD partition probes to try, see
 *         'parse_mtd_partitions()' for more information
 * @parser_data: MTD partition parser-specific data
 * @parts: fallback partition information to register, if parsing fails;
 *         only valid if %nr_parts > %0
 * @nr_parts: the number of partitions in parts, if zero then the full
 *            MTD device is registered if no partition info is found
 *
 * This function aggregates MTD partitions parsing (done by
 * 'parse_mtd_partitions()') and MTD device and partitions registering. It
 * basically follows the most common pattern found in many MTD drivers:
 *
 * * If the MTD_PARTITIONED_MASTER option is set, then the device as a whole is
 *   registered first.
 * * Then It tries to probe partitions on MTD device @mtd using parsers
 *   specified in @types (if @types is %NULL, then the default list of parsers
 *   is used, see 'parse_mtd_partitions()' for more information). If none are
 *   found this functions tries to fallback to information specified in
 *   @parts/@nr_parts.
 * * If no partitions were found this function just registers the MTD device
 *   @mtd and exits.
 *
 * Returns zero in case of success and a negative error code in case of failure.
 */
int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
			      struct mtd_part_parser_data *parser_data,
			      const struct mtd_partition *parts,
			      int nr_parts)
{
	int ret;

	mtd_set_dev_defaults(mtd);

	ret = mtd_otp_nvmem_add(mtd);
	if (ret)
		goto out;

	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) {
		ret = add_mtd_device(mtd);
		if (ret)
			goto out;
	}

	/* Prefer parsed partitions over driver-provided fallback */
	ret = parse_mtd_partitions(mtd, types, parser_data);
	if (ret == -EPROBE_DEFER)
		goto out;

	if (ret > 0)
		ret = 0;
	else if (nr_parts)
		ret = add_mtd_partitions(mtd, parts, nr_parts);
	else if (!device_is_registered(&mtd->dev))
		ret = add_mtd_device(mtd);
	else
		ret = 0;

	if (ret)
		goto out;

	/*
	 * FIXME: some drivers unfortunately call this function more than once.
	 * So we have to check if we've already assigned the reboot notifier.
	 *
	 * Generally, we can make multiple calls work for most cases, but it
	 * does cause problems with parse_mtd_partitions() above (e.g.,
	 * cmdlineparts will register partitions more than once).
	 */
	WARN_ONCE(mtd->_reboot && mtd->reboot_notifier.notifier_call,
		  "MTD already registered\n");
	if (mtd->_reboot && !mtd->reboot_notifier.notifier_call) {
		mtd->reboot_notifier.notifier_call = mtd_reboot_notifier;
		register_reboot_notifier(&mtd->reboot_notifier);
	}

out:
	if (ret) {
		nvmem_unregister(mtd->otp_user_nvmem);
		nvmem_unregister(mtd->otp_factory_nvmem);
	}

	if (ret && device_is_registered(&mtd->dev))
		del_mtd_device(mtd);

	return ret;
}
EXPORT_SYMBOL_GPL(mtd_device_parse_register);

/**
 * mtd_device_unregister - unregister an existing MTD device.
 *
 * @master: the MTD device to unregister.  This will unregister both the master
 *          and any partitions if registered.
 */
int mtd_device_unregister(struct mtd_info *master)
{
	int err;

	if (master->_reboot) {
		unregister_reboot_notifier(&master->reboot_notifier);
		memset(&master->reboot_notifier, 0, sizeof(master->reboot_notifier));
	}

	nvmem_unregister(master->otp_user_nvmem);
	nvmem_unregister(master->otp_factory_nvmem);

	err = del_mtd_partitions(master);
	if (err)
		return err;

	if (!device_is_registered(&master->dev))
		return 0;

	return del_mtd_device(master);
}
EXPORT_SYMBOL_GPL(mtd_device_unregister);

/**
 *	register_mtd_user - register a 'user' of MTD devices.
 *	@new: pointer to notifier info structure
 *
 *	Registers a pair of callbacks function to be called upon addition
 *	or removal of MTD devices. Causes the 'add' callback to be immediately
 *	invoked for each MTD device currently present in the system.
 */
void register_mtd_user (struct mtd_notifier *new)
{
	struct mtd_info *mtd;

	mutex_lock(&mtd_table_mutex);

	list_add(&new->list, &mtd_notifiers);

	__module_get(THIS_MODULE);

	mtd_for_each_device(mtd)
		new->add(mtd);

	mutex_unlock(&mtd_table_mutex);
}
EXPORT_SYMBOL_GPL(register_mtd_user);

/**
 *	unregister_mtd_user - unregister a 'user' of MTD devices.
 *	@old: pointer to notifier info structure
 *
 *	Removes a callback function pair from the list of 'users' to be
 *	notified upon addition or removal of MTD devices. Causes the
 *	'remove' callback to be immediately invoked for each MTD device
 *	currently present in the system.
 */
int unregister_mtd_user (struct mtd_notifier *old)
{
	struct mtd_info *mtd;

	mutex_lock(&mtd_table_mutex);

	module_put(THIS_MODULE);

	mtd_for_each_device(mtd)
		old->remove(mtd);

	list_del(&old->list);
	mutex_unlock(&mtd_table_mutex);
	return 0;
}
EXPORT_SYMBOL_GPL(unregister_mtd_user);

/**
 *	get_mtd_device - obtain a validated handle for an MTD device
 *	@mtd: last known address of the required MTD device
 *	@num: internal device number of the required MTD device
 *
 *	Given a number and NULL address, return the num'th entry in the device
 *	table, if any.	Given an address and num == -1, search the device table
 *	for a device with that address and return if it's still present. Given
 *	both, return the num'th driver only if its address matches. Return
 *	error code if not.
 */
struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num)
{
	struct mtd_info *ret = NULL, *other;
	int err = -ENODEV;

	mutex_lock(&mtd_table_mutex);

	if (num == -1) {
		mtd_for_each_device(other) {
			if (other == mtd) {
				ret = mtd;
				break;
			}
		}
	} else if (num >= 0) {
		ret = idr_find(&mtd_idr, num);
		if (mtd && mtd != ret)
			ret = NULL;
	}

	if (!ret) {
		ret = ERR_PTR(err);
		goto out;
	}

	err = __get_mtd_device(ret);
	if (err)
		ret = ERR_PTR(err);
out:
	mutex_unlock(&mtd_table_mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(get_mtd_device);


int __get_mtd_device(struct mtd_info *mtd)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int err;

	if (master->_get_device) {
		err = master->_get_device(mtd);
		if (err)
			return err;
	}

	if (!try_module_get(master->owner)) {
		if (master->_put_device)
			master->_put_device(master);
		return -ENODEV;
	}

	while (mtd) {
		if (mtd != master)
			kref_get(&mtd->refcnt);
		mtd = mtd->parent;
	}

	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
		kref_get(&master->refcnt);

	return 0;
}
EXPORT_SYMBOL_GPL(__get_mtd_device);

/**
 * of_get_mtd_device_by_node - obtain an MTD device associated with a given node
 *
 * @np: device tree node
 */
struct mtd_info *of_get_mtd_device_by_node(struct device_node *np)
{
	struct mtd_info *mtd = NULL;
	struct mtd_info *tmp;
	int err;

	mutex_lock(&mtd_table_mutex);

	err = -EPROBE_DEFER;
	mtd_for_each_device(tmp) {
		if (mtd_get_of_node(tmp) == np) {
			mtd = tmp;
			err = __get_mtd_device(mtd);
			break;
		}
	}

	mutex_unlock(&mtd_table_mutex);

	return err ? ERR_PTR(err) : mtd;
}
EXPORT_SYMBOL_GPL(of_get_mtd_device_by_node);

/**
 *	get_mtd_device_nm - obtain a validated handle for an MTD device by
 *	device name
 *	@name: MTD device name to open
 *
 * 	This function returns MTD device description structure in case of
 * 	success and an error code in case of failure.
 */
struct mtd_info *get_mtd_device_nm(const char *name)
{
	int err = -ENODEV;
	struct mtd_info *mtd = NULL, *other;

	mutex_lock(&mtd_table_mutex);

	mtd_for_each_device(other) {
		if (!strcmp(name, other->name)) {
			mtd = other;
			break;
		}
	}

	if (!mtd)
		goto out_unlock;

	err = __get_mtd_device(mtd);
	if (err)
		goto out_unlock;

	mutex_unlock(&mtd_table_mutex);
	return mtd;

out_unlock:
	mutex_unlock(&mtd_table_mutex);
	return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(get_mtd_device_nm);

void put_mtd_device(struct mtd_info *mtd)
{
	mutex_lock(&mtd_table_mutex);
	__put_mtd_device(mtd);
	mutex_unlock(&mtd_table_mutex);

}
EXPORT_SYMBOL_GPL(put_mtd_device);

void __put_mtd_device(struct mtd_info *mtd)
{
	struct mtd_info *master = mtd_get_master(mtd);

	while (mtd) {
		/* kref_put() can relese mtd, so keep a reference mtd->parent */
		struct mtd_info *parent = mtd->parent;

		if (mtd != master)
			kref_put(&mtd->refcnt, mtd_device_release);
		mtd = parent;
	}

	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
		kref_put(&master->refcnt, mtd_device_release);

	module_put(master->owner);

	/* must be the last as master can be freed in the _put_device */
	if (master->_put_device)
		master->_put_device(master);
}
EXPORT_SYMBOL_GPL(__put_mtd_device);

/*
 * Erase is an synchronous operation. Device drivers are epected to return a
 * negative error code if the operation failed and update instr->fail_addr
 * to point the portion that was not properly erased.
 */
int mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	struct mtd_info *master = mtd_get_master(mtd);
	u64 mst_ofs = mtd_get_master_ofs(mtd, 0);
	struct erase_info adjinstr;
	int ret;

	instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
	adjinstr = *instr;

	if (!mtd->erasesize || !master->_erase)
		return -ENOTSUPP;

	if (instr->addr >= mtd->size || instr->len > mtd->size - instr->addr)
		return -EINVAL;
	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;

	if (!instr->len)
		return 0;

	ledtrig_mtd_activity();

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
		adjinstr.addr = (loff_t)mtd_div_by_eb(instr->addr, mtd) *
				master->erasesize;
		adjinstr.len = ((u64)mtd_div_by_eb(instr->addr + instr->len, mtd) *
				master->erasesize) -
			       adjinstr.addr;
	}

	adjinstr.addr += mst_ofs;

	ret = master->_erase(master, &adjinstr);

	if (adjinstr.fail_addr != MTD_FAIL_ADDR_UNKNOWN) {
		instr->fail_addr = adjinstr.fail_addr - mst_ofs;
		if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
			instr->fail_addr = mtd_div_by_eb(instr->fail_addr,
							 master);
			instr->fail_addr *= mtd->erasesize;
		}
	}

	return ret;
}
EXPORT_SYMBOL_GPL(mtd_erase);
ALLOW_ERROR_INJECTION(mtd_erase, ERRNO);

/*
 * This stuff for eXecute-In-Place. phys is optional and may be set to NULL.
 */
int mtd_point(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
	      void **virt, resource_size_t *phys)
{
	struct mtd_info *master = mtd_get_master(mtd);

	*retlen = 0;
	*virt = NULL;
	if (phys)
		*phys = 0;
	if (!master->_point)
		return -EOPNOTSUPP;
	if (from < 0 || from >= mtd->size || len > mtd->size - from)
		return -EINVAL;
	if (!len)
		return 0;

	from = mtd_get_master_ofs(mtd, from);
	return master->_point(master, from, len, retlen, virt, phys);
}
EXPORT_SYMBOL_GPL(mtd_point);

/* We probably shouldn't allow XIP if the unpoint isn't a NULL */
int mtd_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->_unpoint)
		return -EOPNOTSUPP;
	if (from < 0 || from >= mtd->size || len > mtd->size - from)
		return -EINVAL;
	if (!len)
		return 0;
	return master->_unpoint(master, mtd_get_master_ofs(mtd, from), len);
}
EXPORT_SYMBOL_GPL(mtd_unpoint);

/*
 * Allow NOMMU mmap() to directly map the device (if not NULL)
 * - return the address to which the offset maps
 * - return -ENOSYS to indicate refusal to do the mapping
 */
unsigned long mtd_get_unmapped_area(struct mtd_info *mtd, unsigned long len,
				    unsigned long offset, unsigned long flags)
{
	size_t retlen;
	void *virt;
	int ret;

	ret = mtd_point(mtd, offset, len, &retlen, &virt, NULL);
	if (ret)
		return ret;
	if (retlen != len) {
		mtd_unpoint(mtd, offset, retlen);
		return -ENOSYS;
	}
	return (unsigned long)virt;
}
EXPORT_SYMBOL_GPL(mtd_get_unmapped_area);

static void mtd_update_ecc_stats(struct mtd_info *mtd, struct mtd_info *master,
				 const struct mtd_ecc_stats *old_stats)
{
	struct mtd_ecc_stats diff;

	if (master == mtd)
		return;

	diff = master->ecc_stats;
	diff.failed -= old_stats->failed;
	diff.corrected -= old_stats->corrected;

	while (mtd->parent) {
		mtd->ecc_stats.failed += diff.failed;
		mtd->ecc_stats.corrected += diff.corrected;
		mtd = mtd->parent;
	}
}

int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
	     u_char *buf)
{
	struct mtd_oob_ops ops = {
		.len = len,
		.datbuf = buf,
	};
	int ret;

	ret = mtd_read_oob(mtd, from, &ops);
	*retlen = ops.retlen;

	WARN_ON_ONCE(*retlen != len && mtd_is_bitflip_or_eccerr(ret));

	return ret;
}
EXPORT_SYMBOL_GPL(mtd_read);
ALLOW_ERROR_INJECTION(mtd_read, ERRNO);

int mtd_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
	      const u_char *buf)
{
	struct mtd_oob_ops ops = {
		.len = len,
		.datbuf = (u8 *)buf,
	};
	int ret;

	ret = mtd_write_oob(mtd, to, &ops);
	*retlen = ops.retlen;

	return ret;
}
EXPORT_SYMBOL_GPL(mtd_write);
ALLOW_ERROR_INJECTION(mtd_write, ERRNO);

/*
 * In blackbox flight recorder like scenarios we want to make successful writes
 * in interrupt context. panic_write() is only intended to be called when its
 * known the kernel is about to panic and we need the write to succeed. Since
 * the kernel is not going to be running for much longer, this function can
 * break locks and delay to ensure the write succeeds (but not sleep).
 */
int mtd_panic_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
		    const u_char *buf)
{
	struct mtd_info *master = mtd_get_master(mtd);

	*retlen = 0;
	if (!master->_panic_write)
		return -EOPNOTSUPP;
	if (to < 0 || to >= mtd->size || len > mtd->size - to)
		return -EINVAL;
	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;
	if (!len)
		return 0;
	if (!master->oops_panic_write)
		master->oops_panic_write = true;

	return master->_panic_write(master, mtd_get_master_ofs(mtd, to), len,
				    retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_panic_write);

static int mtd_check_oob_ops(struct mtd_info *mtd, loff_t offs,
			     struct mtd_oob_ops *ops)
{
	/*
	 * Some users are setting ->datbuf or ->oobbuf to NULL, but are leaving
	 * ->len or ->ooblen uninitialized. Force ->len and ->ooblen to 0 in
	 *  this case.
	 */
	if (!ops->datbuf)
		ops->len = 0;

	if (!ops->oobbuf)
		ops->ooblen = 0;

	if (offs < 0 || offs + ops->len > mtd->size)
		return -EINVAL;

	if (ops->ooblen) {
		size_t maxooblen;

		if (ops->ooboffs >= mtd_oobavail(mtd, ops))
			return -EINVAL;

		maxooblen = ((size_t)(mtd_div_by_ws(mtd->size, mtd) -
				      mtd_div_by_ws(offs, mtd)) *
			     mtd_oobavail(mtd, ops)) - ops->ooboffs;
		if (ops->ooblen > maxooblen)
			return -EINVAL;
	}

	return 0;
}

static int mtd_read_oob_std(struct mtd_info *mtd, loff_t from,
			    struct mtd_oob_ops *ops)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int ret;

	from = mtd_get_master_ofs(mtd, from);
	if (master->_read_oob)
		ret = master->_read_oob(master, from, ops);
	else
		ret = master->_read(master, from, ops->len, &ops->retlen,
				    ops->datbuf);

	return ret;
}

static int mtd_write_oob_std(struct mtd_info *mtd, loff_t to,
			     struct mtd_oob_ops *ops)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int ret;

	to = mtd_get_master_ofs(mtd, to);
	if (master->_write_oob)
		ret = master->_write_oob(master, to, ops);
	else
		ret = master->_write(master, to, ops->len, &ops->retlen,
				     ops->datbuf);

	return ret;
}

static int mtd_io_emulated_slc(struct mtd_info *mtd, loff_t start, bool read,
			       struct mtd_oob_ops *ops)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int ngroups = mtd_pairing_groups(master);
	int npairs = mtd_wunit_per_eb(master) / ngroups;
	struct mtd_oob_ops adjops = *ops;
	unsigned int wunit, oobavail;
	struct mtd_pairing_info info;
	int max_bitflips = 0;
	u32 ebofs, pageofs;
	loff_t base, pos;

	ebofs = mtd_mod_by_eb(start, mtd);
	base = (loff_t)mtd_div_by_eb(start, mtd) * master->erasesize;
	info.group = 0;
	info.pair = mtd_div_by_ws(ebofs, mtd);
	pageofs = mtd_mod_by_ws(ebofs, mtd);
	oobavail = mtd_oobavail(mtd, ops);

	while (ops->retlen < ops->len || ops->oobretlen < ops->ooblen) {
		int ret;

		if (info.pair >= npairs) {
			info.pair = 0;
			base += master->erasesize;
		}

		wunit = mtd_pairing_info_to_wunit(master, &info);
		pos = mtd_wunit_to_offset(mtd, base, wunit);

		adjops.len = ops->len - ops->retlen;
		if (adjops.len > mtd->writesize - pageofs)
			adjops.len = mtd->writesize - pageofs;

		adjops.ooblen = ops->ooblen - ops->oobretlen;
		if (adjops.ooblen > oobavail - adjops.ooboffs)
			adjops.ooblen = oobavail - adjops.ooboffs;

		if (read) {
			ret = mtd_read_oob_std(mtd, pos + pageofs, &adjops);
			if (ret > 0)
				max_bitflips = max(max_bitflips, ret);
		} else {
			ret = mtd_write_oob_std(mtd, pos + pageofs, &adjops);
		}

		if (ret < 0)
			return ret;

		max_bitflips = max(max_bitflips, ret);
		ops->retlen += adjops.retlen;
		ops->oobretlen += adjops.oobretlen;
		adjops.datbuf += adjops.retlen;
		adjops.oobbuf += adjops.oobretlen;
		adjops.ooboffs = 0;
		pageofs = 0;
		info.pair++;
	}

	return max_bitflips;
}

int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
{
	struct mtd_info *master = mtd_get_master(mtd);
	struct mtd_ecc_stats old_stats = master->ecc_stats;
	int ret_code;

	ops->retlen = ops->oobretlen = 0;

	ret_code = mtd_check_oob_ops(mtd, from, ops);
	if (ret_code)
		return ret_code;

	ledtrig_mtd_activity();

	/* Check the validity of a potential fallback on mtd->_read */
	if (!master->_read_oob && (!master->_read || ops->oobbuf))
		return -EOPNOTSUPP;

	if (ops->stats)
		memset(ops->stats, 0, sizeof(*ops->stats));

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
		ret_code = mtd_io_emulated_slc(mtd, from, true, ops);
	else
		ret_code = mtd_read_oob_std(mtd, from, ops);

	mtd_update_ecc_stats(mtd, master, &old_stats);

	/*
	 * In cases where ops->datbuf != NULL, mtd->_read_oob() has semantics
	 * similar to mtd->_read(), returning a non-negative integer
	 * representing max bitflips. In other cases, mtd->_read_oob() may
	 * return -EUCLEAN. In all cases, perform similar logic to mtd_read().
	 */
	if (unlikely(ret_code < 0))
		return ret_code;
	if (mtd->ecc_strength == 0)
		return 0;	/* device lacks ecc */
	if (ops->stats)
		ops->stats->max_bitflips = ret_code;
	return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0;
}
EXPORT_SYMBOL_GPL(mtd_read_oob);

int mtd_write_oob(struct mtd_info *mtd, loff_t to,
				struct mtd_oob_ops *ops)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int ret;

	ops->retlen = ops->oobretlen = 0;

	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;

	ret = mtd_check_oob_ops(mtd, to, ops);
	if (ret)
		return ret;

	ledtrig_mtd_activity();

	/* Check the validity of a potential fallback on mtd->_write */
	if (!master->_write_oob && (!master->_write || ops->oobbuf))
		return -EOPNOTSUPP;

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
		return mtd_io_emulated_slc(mtd, to, false, ops);

	return mtd_write_oob_std(mtd, to, ops);
}
EXPORT_SYMBOL_GPL(mtd_write_oob);

/**
 * mtd_ooblayout_ecc - Get the OOB region definition of a specific ECC section
 * @mtd: MTD device structure
 * @section: ECC section. Depending on the layout you may have all the ECC
 *	     bytes stored in a single contiguous section, or one section
 *	     per ECC chunk (and sometime several sections for a single ECC
 *	     ECC chunk)
 * @oobecc: OOB region struct filled with the appropriate ECC position
 *	    information
 *
 * This function returns ECC section information in the OOB area. If you want
 * to get all the ECC bytes information, then you should call
 * mtd_ooblayout_ecc(mtd, section++, oobecc) until it returns -ERANGE.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,
		      struct mtd_oob_region *oobecc)
{
	struct mtd_info *master = mtd_get_master(mtd);

	memset(oobecc, 0, sizeof(*oobecc));

	if (!master || section < 0)
		return -EINVAL;

	if (!master->ooblayout || !master->ooblayout->ecc)
		return -ENOTSUPP;

	return master->ooblayout->ecc(master, section, oobecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_ecc);

/**
 * mtd_ooblayout_free - Get the OOB region definition of a specific free
 *			section
 * @mtd: MTD device structure
 * @section: Free section you are interested in. Depending on the layout
 *	     you may have all the free bytes stored in a single contiguous
 *	     section, or one section per ECC chunk plus an extra section
 *	     for the remaining bytes (or other funky layout).
 * @oobfree: OOB region struct filled with the appropriate free position
 *	     information
 *
 * This function returns free bytes position in the OOB area. If you want
 * to get all the free bytes information, then you should call
 * mtd_ooblayout_free(mtd, section++, oobfree) until it returns -ERANGE.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_free(struct mtd_info *mtd, int section,
		       struct mtd_oob_region *oobfree)
{
	struct mtd_info *master = mtd_get_master(mtd);

	memset(oobfree, 0, sizeof(*oobfree));

	if (!master || section < 0)
		return -EINVAL;

	if (!master->ooblayout || !master->ooblayout->free)
		return -ENOTSUPP;

	return master->ooblayout->free(master, section, oobfree);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_free);

/**
 * mtd_ooblayout_find_region - Find the region attached to a specific byte
 * @mtd: mtd info structure
 * @byte: the byte we are searching for
 * @sectionp: pointer where the section id will be stored
 * @oobregion: used to retrieve the ECC position
 * @iter: iterator function. Should be either mtd_ooblayout_free or
 *	  mtd_ooblayout_ecc depending on the region type you're searching for
 *
 * This function returns the section id and oobregion information of a
 * specific byte. For example, say you want to know where the 4th ECC byte is
 * stored, you'll use:
 *
 * mtd_ooblayout_find_region(mtd, 3, &section, &oobregion, mtd_ooblayout_ecc);
 *
 * Returns zero on success, a negative error code otherwise.
 */
static int mtd_ooblayout_find_region(struct mtd_info *mtd, int byte,
				int *sectionp, struct mtd_oob_region *oobregion,
				int (*iter)(struct mtd_info *,
					    int section,
					    struct mtd_oob_region *oobregion))
{
	int pos = 0, ret, section = 0;

	memset(oobregion, 0, sizeof(*oobregion));

	while (1) {
		ret = iter(mtd, section, oobregion);
		if (ret)
			return ret;

		if (pos + oobregion->length > byte)
			break;

		pos += oobregion->length;
		section++;
	}

	/*
	 * Adjust region info to make it start at the beginning at the
	 * 'start' ECC byte.
	 */
	oobregion->offset += byte - pos;
	oobregion->length -= byte - pos;
	*sectionp = section;

	return 0;
}

/**
 * mtd_ooblayout_find_eccregion - Find the ECC region attached to a specific
 *				  ECC byte
 * @mtd: mtd info structure
 * @eccbyte: the byte we are searching for
 * @section: pointer where the section id will be stored
 * @oobregion: OOB region information
 *
 * Works like mtd_ooblayout_find_region() except it searches for a specific ECC
 * byte.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_find_eccregion(struct mtd_info *mtd, int eccbyte,
				 int *section,
				 struct mtd_oob_region *oobregion)
{
	return mtd_ooblayout_find_region(mtd, eccbyte, section, oobregion,
					 mtd_ooblayout_ecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_find_eccregion);

/**
 * mtd_ooblayout_get_bytes - Extract OOB bytes from the oob buffer
 * @mtd: mtd info structure
 * @buf: destination buffer to store OOB bytes
 * @oobbuf: OOB buffer
 * @start: first byte to retrieve
 * @nbytes: number of bytes to retrieve
 * @iter: section iterator
 *
 * Extract bytes attached to a specific category (ECC or free)
 * from the OOB buffer and copy them into buf.
 *
 * Returns zero on success, a negative error code otherwise.
 */
static int mtd_ooblayout_get_bytes(struct mtd_info *mtd, u8 *buf,
				const u8 *oobbuf, int start, int nbytes,
				int (*iter)(struct mtd_info *,
					    int section,
					    struct mtd_oob_region *oobregion))
{
	struct mtd_oob_region oobregion;
	int section, ret;

	ret = mtd_ooblayout_find_region(mtd, start, &section,
					&oobregion, iter);

	while (!ret) {
		int cnt;

		cnt = min_t(int, nbytes, oobregion.length);
		memcpy(buf, oobbuf + oobregion.offset, cnt);
		buf += cnt;
		nbytes -= cnt;

		if (!nbytes)
			break;

		ret = iter(mtd, ++section, &oobregion);
	}

	return ret;
}

/**
 * mtd_ooblayout_set_bytes - put OOB bytes into the oob buffer
 * @mtd: mtd info structure
 * @buf: source buffer to get OOB bytes from
 * @oobbuf: OOB buffer
 * @start: first OOB byte to set
 * @nbytes: number of OOB bytes to set
 * @iter: section iterator
 *
 * Fill the OOB buffer with data provided in buf. The category (ECC or free)
 * is selected by passing the appropriate iterator.
 *
 * Returns zero on success, a negative error code otherwise.
 */
static int mtd_ooblayout_set_bytes(struct mtd_info *mtd, const u8 *buf,
				u8 *oobbuf, int start, int nbytes,
				int (*iter)(struct mtd_info *,
					    int section,
					    struct mtd_oob_region *oobregion))
{
	struct mtd_oob_region oobregion;
	int section, ret;

	ret = mtd_ooblayout_find_region(mtd, start, &section,
					&oobregion, iter);

	while (!ret) {
		int cnt;

		cnt = min_t(int, nbytes, oobregion.length);
		memcpy(oobbuf + oobregion.offset, buf, cnt);
		buf += cnt;
		nbytes -= cnt;

		if (!nbytes)
			break;

		ret = iter(mtd, ++section, &oobregion);
	}

	return ret;
}

/**
 * mtd_ooblayout_count_bytes - count the number of bytes in a OOB category
 * @mtd: mtd info structure
 * @iter: category iterator
 *
 * Count the number of bytes in a given category.
 *
 * Returns a positive value on success, a negative error code otherwise.
 */
static int mtd_ooblayout_count_bytes(struct mtd_info *mtd,
				int (*iter)(struct mtd_info *,
					    int section,
					    struct mtd_oob_region *oobregion))
{
	struct mtd_oob_region oobregion;
	int section = 0, ret, nbytes = 0;

	while (1) {
		ret = iter(mtd, section++, &oobregion);
		if (ret) {
			if (ret == -ERANGE)
				ret = nbytes;
			break;
		}

		nbytes += oobregion.length;
	}

	return ret;
}

/**
 * mtd_ooblayout_get_eccbytes - extract ECC bytes from the oob buffer
 * @mtd: mtd info structure
 * @eccbuf: destination buffer to store ECC bytes
 * @oobbuf: OOB buffer
 * @start: first ECC byte to retrieve
 * @nbytes: number of ECC bytes to retrieve
 *
 * Works like mtd_ooblayout_get_bytes(), except it acts on ECC bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_get_eccbytes(struct mtd_info *mtd, u8 *eccbuf,
			       const u8 *oobbuf, int start, int nbytes)
{
	return mtd_ooblayout_get_bytes(mtd, eccbuf, oobbuf, start, nbytes,
				       mtd_ooblayout_ecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_get_eccbytes);

/**
 * mtd_ooblayout_set_eccbytes - set ECC bytes into the oob buffer
 * @mtd: mtd info structure
 * @eccbuf: source buffer to get ECC bytes from
 * @oobbuf: OOB buffer
 * @start: first ECC byte to set
 * @nbytes: number of ECC bytes to set
 *
 * Works like mtd_ooblayout_set_bytes(), except it acts on ECC bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_set_eccbytes(struct mtd_info *mtd, const u8 *eccbuf,
			       u8 *oobbuf, int start, int nbytes)
{
	return mtd_ooblayout_set_bytes(mtd, eccbuf, oobbuf, start, nbytes,
				       mtd_ooblayout_ecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_set_eccbytes);

/**
 * mtd_ooblayout_get_databytes - extract data bytes from the oob buffer
 * @mtd: mtd info structure
 * @databuf: destination buffer to store ECC bytes
 * @oobbuf: OOB buffer
 * @start: first ECC byte to retrieve
 * @nbytes: number of ECC bytes to retrieve
 *
 * Works like mtd_ooblayout_get_bytes(), except it acts on free bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_get_databytes(struct mtd_info *mtd, u8 *databuf,
				const u8 *oobbuf, int start, int nbytes)
{
	return mtd_ooblayout_get_bytes(mtd, databuf, oobbuf, start, nbytes,
				       mtd_ooblayout_free);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_get_databytes);

/**
 * mtd_ooblayout_set_databytes - set data bytes into the oob buffer
 * @mtd: mtd info structure
 * @databuf: source buffer to get data bytes from
 * @oobbuf: OOB buffer
 * @start: first ECC byte to set
 * @nbytes: number of ECC bytes to set
 *
 * Works like mtd_ooblayout_set_bytes(), except it acts on free bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_set_databytes(struct mtd_info *mtd, const u8 *databuf,
				u8 *oobbuf, int start, int nbytes)
{
	return mtd_ooblayout_set_bytes(mtd, databuf, oobbuf, start, nbytes,
				       mtd_ooblayout_free);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_set_databytes);

/**
 * mtd_ooblayout_count_freebytes - count the number of free bytes in OOB
 * @mtd: mtd info structure
 *
 * Works like mtd_ooblayout_count_bytes(), except it count free bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_count_freebytes(struct mtd_info *mtd)
{
	return mtd_ooblayout_count_bytes(mtd, mtd_ooblayout_free);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_count_freebytes);

/**
 * mtd_ooblayout_count_eccbytes - count the number of ECC bytes in OOB
 * @mtd: mtd info structure
 *
 * Works like mtd_ooblayout_count_bytes(), except it count ECC bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_count_eccbytes(struct mtd_info *mtd)
{
	return mtd_ooblayout_count_bytes(mtd, mtd_ooblayout_ecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_count_eccbytes);

/*
 * Method to access the protection register area, present in some flash
 * devices. The user data is one time programmable but the factory data is read
 * only.
 */
int mtd_get_fact_prot_info(struct mtd_info *mtd, size_t len, size_t *retlen,
			   struct otp_info *buf)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->_get_fact_prot_info)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	return master->_get_fact_prot_info(master, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_get_fact_prot_info);

int mtd_read_fact_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,
			   size_t *retlen, u_char *buf)
{
	struct mtd_info *master = mtd_get_master(mtd);

	*retlen = 0;
	if (!master->_read_fact_prot_reg)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	return master->_read_fact_prot_reg(master, from, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_read_fact_prot_reg);

int mtd_get_user_prot_info(struct mtd_info *mtd, size_t len, size_t *retlen,
			   struct otp_info *buf)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->_get_user_prot_info)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	return master->_get_user_prot_info(master, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_get_user_prot_info);

int mtd_read_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,
			   size_t *retlen, u_char *buf)
{
	struct mtd_info *master = mtd_get_master(mtd);

	*retlen = 0;
	if (!master->_read_user_prot_reg)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	return master->_read_user_prot_reg(master, from, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_read_user_prot_reg);

int mtd_write_user_prot_reg(struct mtd_info *mtd, loff_t to, size_t len,
			    size_t *retlen, const u_char *buf)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int ret;

	*retlen = 0;
	if (!master->_write_user_prot_reg)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	ret = master->_write_user_prot_reg(master, to, len, retlen, buf);
	if (ret)
		return ret;

	/*
	 * If no data could be written at all, we are out of memory and
	 * must return -ENOSPC.
	 */
	return (*retlen) ? 0 : -ENOSPC;
}
EXPORT_SYMBOL_GPL(mtd_write_user_prot_reg);

int mtd_lock_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->_lock_user_prot_reg)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	return master->_lock_user_prot_reg(master, from, len);
}
EXPORT_SYMBOL_GPL(mtd_lock_user_prot_reg);

int mtd_erase_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->_erase_user_prot_reg)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	return master->_erase_user_prot_reg(master, from, len);
}
EXPORT_SYMBOL_GPL(mtd_erase_user_prot_reg);

/* Chip-supported device locking */
int mtd_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->_lock)
		return -EOPNOTSUPP;
	if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
		return -EINVAL;
	if (!len)
		return 0;

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
		ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
		len = (u64)mtd_div_by_eb(len, mtd) * master->erasesize;
	}

	return master->_lock(master, mtd_get_master_ofs(mtd, ofs), len);
}
EXPORT_SYMBOL_GPL(mtd_lock);

int mtd_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->_unlock)
		return -EOPNOTSUPP;
	if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
		return -EINVAL;
	if (!len)
		return 0;

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
		ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
		len = (u64)mtd_div_by_eb(len, mtd) * master->erasesize;
	}

	return master->_unlock(master, mtd_get_master_ofs(mtd, ofs), len);
}
EXPORT_SYMBOL_GPL(mtd_unlock);

int mtd_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (!master->_is_locked)
		return -EOPNOTSUPP;
	if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
		return -EINVAL;
	if (!len)
		return 0;

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
		ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
		len = (u64)mtd_div_by_eb(len, mtd) * master->erasesize;
	}

	return master->_is_locked(master, mtd_get_master_ofs(mtd, ofs), len);
}
EXPORT_SYMBOL_GPL(mtd_is_locked);

int mtd_block_isreserved(struct mtd_info *mtd, loff_t ofs)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (ofs < 0 || ofs >= mtd->size)
		return -EINVAL;
	if (!master->_block_isreserved)
		return 0;

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
		ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;

	return master->_block_isreserved(master, mtd_get_master_ofs(mtd, ofs));
}
EXPORT_SYMBOL_GPL(mtd_block_isreserved);

int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs)
{
	struct mtd_info *master = mtd_get_master(mtd);

	if (ofs < 0 || ofs >= mtd->size)
		return -EINVAL;
	if (!master->_block_isbad)
		return 0;

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
		ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;

	return master->_block_isbad(master, mtd_get_master_ofs(mtd, ofs));
}
EXPORT_SYMBOL_GPL(mtd_block_isbad);

int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs)
{
	struct mtd_info *master = mtd_get_master(mtd);
	int ret;

	if (!master->_block_markbad)
		return -EOPNOTSUPP;
	if (ofs < 0 || ofs >= mtd->size)
		return -EINVAL;
	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;

	if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
		ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;

	ret = master->_block_markbad(master, mtd_get_master_ofs(mtd, ofs));
	if (ret)
		return ret;

	while (mtd->parent) {
		mtd->ecc_stats.badblocks++;
		mtd = mtd->parent;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(mtd_block_markbad);
ALLOW_ERROR_INJECTION(mtd_block_markbad, ERRNO);

/*
 * default_mtd_writev - the default writev method
 * @mtd: mtd device description object pointer
 * @vecs: the vectors to write
 * @count: count of vectors in @vecs
 * @to: the MTD device offset to write to
 * @retlen: on exit contains the count of bytes written to the MTD device.
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int default_mtd_writev(struct mtd_info *mtd, const struct kvec *vecs,
			      unsigned long count, loff_t to, size_t *retlen)
{
	unsigned long i;
	size_t totlen = 0, thislen;
	int ret = 0;

	for (i = 0; i < count; i++) {
		if (!vecs[i].iov_len)
			continue;
		ret = mtd_write(mtd, to, vecs[i].iov_len, &thislen,
				vecs[i].iov_base);
		totlen += thislen;
		if (ret || thislen != vecs[i].iov_len)
			break;
		to += vecs[i].iov_len;
	}
	*retlen = totlen;
	return ret;
}

/*
 * mtd_writev - the vector-based MTD write method
 * @mtd: mtd device description object pointer
 * @vecs: the vectors to write
 * @count: count of vectors in @vecs
 * @to: the MTD device offset to write to
 * @retlen: on exit contains the count of bytes written to the MTD device.
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
int mtd_writev(struct mtd_info *mtd, const struct kvec *vecs,
	       unsigned long count, loff_t to, size_t *retlen)
{
	struct mtd_info *master = mtd_get_master(mtd);

	*retlen = 0;
	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;

	if (!master->_writev)
		return default_mtd_writev(mtd, vecs, count, to, retlen);

	return master->_writev(master, vecs, count,
			       mtd_get_master_ofs(mtd, to), retlen);
}
EXPORT_SYMBOL_GPL(mtd_writev);

/**
 * mtd_kmalloc_up_to - allocate a contiguous buffer up to the specified size
 * @mtd: mtd device description object pointer
 * @size: a pointer to the ideal or maximum size of the allocation, points
 *        to the actual allocation size on success.
 *
 * This routine attempts to allocate a contiguous kernel buffer up to
 * the specified size, backing off the size of the request exponentially
 * until the request succeeds or until the allocation size falls below
 * the system page size. This attempts to make sure it does not adversely
 * impact system performance, so when allocating more than one page, we
 * ask the memory allocator to avoid re-trying, swapping, writing back
 * or performing I/O.
 *
 * Note, this function also makes sure that the allocated buffer is aligned to
 * the MTD device's min. I/O unit, i.e. the "mtd->writesize" value.
 *
 * This is called, for example by mtd_{read,write} and jffs2_scan_medium,
 * to handle smaller (i.e. degraded) buffer allocations under low- or
 * fragmented-memory situations where such reduced allocations, from a
 * requested ideal, are allowed.
 *
 * Returns a pointer to the allocated buffer on success; otherwise, NULL.
 */
void *mtd_kmalloc_up_to(const struct mtd_info *mtd, size_t *size)
{
	gfp_t flags = __GFP_NOWARN | __GFP_DIRECT_RECLAIM | __GFP_NORETRY;
	size_t min_alloc = max_t(size_t, mtd->writesize, PAGE_SIZE);
	void *kbuf;

	*size = min_t(size_t, *size, KMALLOC_MAX_SIZE);

	while (*size > min_alloc) {
		kbuf = kmalloc(*size, flags);
		if (kbuf)
			return kbuf;

		*size >>= 1;
		*size = ALIGN(*size, mtd->writesize);
	}

	/*
	 * For the last resort allocation allow 'kmalloc()' to do all sorts of
	 * things (write-back, dropping caches, etc) by using GFP_KERNEL.
	 */
	return kmalloc(*size, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(mtd_kmalloc_up_to);

#ifdef CONFIG_PROC_FS

/*====================================================================*/
/* Support for /proc/mtd */

static int mtd_proc_show(struct seq_file *m, void *v)
{
	struct mtd_info *mtd;

	seq_puts(m, "dev:    size   erasesize  name\n");
	mutex_lock(&mtd_table_mutex);
	mtd_for_each_device(mtd) {
		seq_printf(m, "mtd%d: %8.8llx %8.8x \"%s\"\n",
			   mtd->index, (unsigned long long)mtd->size,
			   mtd->erasesize, mtd->name);
	}
	mutex_unlock(&mtd_table_mutex);
	return 0;
}
#endif /* CONFIG_PROC_FS */

/*====================================================================*/
/* Init code */

static struct backing_dev_info * __init mtd_bdi_init(const char *name)
{
	struct backing_dev_info *bdi;
	int ret;

	bdi = bdi_alloc(NUMA_NO_NODE);
	if (!bdi)
		return ERR_PTR(-ENOMEM);
	bdi->ra_pages = 0;
	bdi->io_pages = 0;

	/*
	 * We put '-0' suffix to the name to get the same name format as we
	 * used to get. Since this is called only once, we get a unique name. 
	 */
	ret = bdi_register(bdi, "%.28s-0", name);
	if (ret)
		bdi_put(bdi);

	return ret ? ERR_PTR(ret) : bdi;
}

static struct proc_dir_entry *proc_mtd;

static int __init init_mtd(void)
{
	int ret;

	ret = class_register(&mtd_class);
	if (ret)
		goto err_reg;

	mtd_bdi = mtd_bdi_init("mtd");
	if (IS_ERR(mtd_bdi)) {
		ret = PTR_ERR(mtd_bdi);
		goto err_bdi;
	}

	proc_mtd = proc_create_single("mtd", 0, NULL, mtd_proc_show);

	ret = init_mtdchar();
	if (ret)
		goto out_procfs;

	dfs_dir_mtd = debugfs_create_dir("mtd", NULL);
	debugfs_create_bool("expert_analysis_mode", 0600, dfs_dir_mtd,
			    &mtd_expert_analysis_mode);

	return 0;

out_procfs:
	if (proc_mtd)
		remove_proc_entry("mtd", NULL);
	bdi_unregister(mtd_bdi);
	bdi_put(mtd_bdi);
err_bdi:
	class_unregister(&mtd_class);
err_reg:
	pr_err("Error registering mtd class or bdi: %d\n", ret);
	return ret;
}

static void __exit cleanup_mtd(void)
{
	debugfs_remove_recursive(dfs_dir_mtd);
	cleanup_mtdchar();
	if (proc_mtd)
		remove_proc_entry("mtd", NULL);
	class_unregister(&mtd_class);
	bdi_unregister(mtd_bdi);
	bdi_put(mtd_bdi);
	idr_destroy(&mtd_idr);
}

module_init(init_mtd);
module_exit(cleanup_mtd);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("Core MTD registration and access routines");