summaryrefslogtreecommitdiffstats
path: root/drivers/usb/gadget/function/f_fs.c
blob: c2592d883f67c45f980c21cfa4181f77fac14760 (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
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
// SPDX-License-Identifier: GPL-2.0+
/*
 * f_fs.c -- user mode file system API for USB composite function controllers
 *
 * Copyright (C) 2010 Samsung Electronics
 * Author: Michal Nazarewicz <mina86@mina86.com>
 *
 * Based on inode.c (GadgetFS) which was:
 * Copyright (C) 2003-2004 David Brownell
 * Copyright (C) 2003 Agilent Technologies
 */


/* #define DEBUG */
/* #define VERBOSE_DEBUG */

#include <linux/blkdev.h>
#include <linux/pagemap.h>
#include <linux/export.h>
#include <linux/hid.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <linux/uio.h>
#include <asm/unaligned.h>

#include <linux/usb/composite.h>
#include <linux/usb/functionfs.h>

#include <linux/aio.h>
#include <linux/mmu_context.h>
#include <linux/poll.h>
#include <linux/eventfd.h>

#include "u_fs.h"
#include "u_f.h"
#include "u_os_desc.h"
#include "configfs.h"

#define FUNCTIONFS_MAGIC	0xa647361 /* Chosen by a honest dice roll ;) */

/* Reference counter handling */
static void ffs_data_get(struct ffs_data *ffs);
static void ffs_data_put(struct ffs_data *ffs);
/* Creates new ffs_data object. */
static struct ffs_data *__must_check ffs_data_new(const char *dev_name)
	__attribute__((malloc));

/* Opened counter handling. */
static void ffs_data_opened(struct ffs_data *ffs);
static void ffs_data_closed(struct ffs_data *ffs);

/* Called with ffs->mutex held; take over ownership of data. */
static int __must_check
__ffs_data_got_descs(struct ffs_data *ffs, char *data, size_t len);
static int __must_check
__ffs_data_got_strings(struct ffs_data *ffs, char *data, size_t len);


/* The function structure ***************************************************/

struct ffs_ep;

struct ffs_function {
	struct usb_configuration	*conf;
	struct usb_gadget		*gadget;
	struct ffs_data			*ffs;

	struct ffs_ep			*eps;
	u8				eps_revmap[16];
	short				*interfaces_nums;

	struct usb_function		function;
};


static struct ffs_function *ffs_func_from_usb(struct usb_function *f)
{
	return container_of(f, struct ffs_function, function);
}


static inline enum ffs_setup_state
ffs_setup_state_clear_cancelled(struct ffs_data *ffs)
{
	return (enum ffs_setup_state)
		cmpxchg(&ffs->setup_state, FFS_SETUP_CANCELLED, FFS_NO_SETUP);
}


static void ffs_func_eps_disable(struct ffs_function *func);
static int __must_check ffs_func_eps_enable(struct ffs_function *func);

static int ffs_func_bind(struct usb_configuration *,
			 struct usb_function *);
static int ffs_func_set_alt(struct usb_function *, unsigned, unsigned);
static void ffs_func_disable(struct usb_function *);
static int ffs_func_setup(struct usb_function *,
			  const struct usb_ctrlrequest *);
static bool ffs_func_req_match(struct usb_function *,
			       const struct usb_ctrlrequest *,
			       bool config0);
static void ffs_func_suspend(struct usb_function *);
static void ffs_func_resume(struct usb_function *);


static int ffs_func_revmap_ep(struct ffs_function *func, u8 num);
static int ffs_func_revmap_intf(struct ffs_function *func, u8 intf);


/* The endpoints structures *************************************************/

struct ffs_ep {
	struct usb_ep			*ep;	/* P: ffs->eps_lock */
	struct usb_request		*req;	/* P: epfile->mutex */

	/* [0]: full speed, [1]: high speed, [2]: super speed */
	struct usb_endpoint_descriptor	*descs[3];

	u8				num;

	int				status;	/* P: epfile->mutex */
};

struct ffs_epfile {
	/* Protects ep->ep and ep->req. */
	struct mutex			mutex;

	struct ffs_data			*ffs;
	struct ffs_ep			*ep;	/* P: ffs->eps_lock */

	struct dentry			*dentry;

	/*
	 * Buffer for holding data from partial reads which may happen since
	 * we’re rounding user read requests to a multiple of a max packet size.
	 *
	 * The pointer is initialised with NULL value and may be set by
	 * __ffs_epfile_read_data function to point to a temporary buffer.
	 *
	 * In normal operation, calls to __ffs_epfile_read_buffered will consume
	 * data from said buffer and eventually free it.  Importantly, while the
	 * function is using the buffer, it sets the pointer to NULL.  This is
	 * all right since __ffs_epfile_read_data and __ffs_epfile_read_buffered
	 * can never run concurrently (they are synchronised by epfile->mutex)
	 * so the latter will not assign a new value to the pointer.
	 *
	 * Meanwhile ffs_func_eps_disable frees the buffer (if the pointer is
	 * valid) and sets the pointer to READ_BUFFER_DROP value.  This special
	 * value is crux of the synchronisation between ffs_func_eps_disable and
	 * __ffs_epfile_read_data.
	 *
	 * Once __ffs_epfile_read_data is about to finish it will try to set the
	 * pointer back to its old value (as described above), but seeing as the
	 * pointer is not-NULL (namely READ_BUFFER_DROP) it will instead free
	 * the buffer.
	 *
	 * == State transitions ==
	 *
	 * • ptr == NULL:  (initial state)
	 *   ◦ __ffs_epfile_read_buffer_free: go to ptr == DROP
	 *   ◦ __ffs_epfile_read_buffered:    nop
	 *   ◦ __ffs_epfile_read_data allocates temp buffer: go to ptr == buf
	 *   ◦ reading finishes:              n/a, not in ‘and reading’ state
	 * • ptr == DROP:
	 *   ◦ __ffs_epfile_read_buffer_free: nop
	 *   ◦ __ffs_epfile_read_buffered:    go to ptr == NULL
	 *   ◦ __ffs_epfile_read_data allocates temp buffer: free buf, nop
	 *   ◦ reading finishes:              n/a, not in ‘and reading’ state
	 * • ptr == buf:
	 *   ◦ __ffs_epfile_read_buffer_free: free buf, go to ptr == DROP
	 *   ◦ __ffs_epfile_read_buffered:    go to ptr == NULL and reading
	 *   ◦ __ffs_epfile_read_data:        n/a, __ffs_epfile_read_buffered
	 *                                    is always called first
	 *   ◦ reading finishes:              n/a, not in ‘and reading’ state
	 * • ptr == NULL and reading:
	 *   ◦ __ffs_epfile_read_buffer_free: go to ptr == DROP and reading
	 *   ◦ __ffs_epfile_read_buffered:    n/a, mutex is held
	 *   ◦ __ffs_epfile_read_data:        n/a, mutex is held
	 *   ◦ reading finishes and …
	 *     … all data read:               free buf, go to ptr == NULL
	 *     … otherwise:                   go to ptr == buf and reading
	 * • ptr == DROP and reading:
	 *   ◦ __ffs_epfile_read_buffer_free: nop
	 *   ◦ __ffs_epfile_read_buffered:    n/a, mutex is held
	 *   ◦ __ffs_epfile_read_data:        n/a, mutex is held
	 *   ◦ reading finishes:              free buf, go to ptr == DROP
	 */
	struct ffs_buffer		*read_buffer;
#define READ_BUFFER_DROP ((struct ffs_buffer *)ERR_PTR(-ESHUTDOWN))

	char				name[5];

	unsigned char			in;	/* P: ffs->eps_lock */
	unsigned char			isoc;	/* P: ffs->eps_lock */

	unsigned char			_pad;
};

struct ffs_buffer {
	size_t length;
	char *data;
	char storage[];
};

/*  ffs_io_data structure ***************************************************/

struct ffs_io_data {
	bool aio;
	bool read;

	struct kiocb *kiocb;
	struct iov_iter data;
	const void *to_free;
	char *buf;

	struct mm_struct *mm;
	struct work_struct work;

	struct usb_ep *ep;
	struct usb_request *req;

	struct ffs_data *ffs;
};

struct ffs_desc_helper {
	struct ffs_data *ffs;
	unsigned interfaces_count;
	unsigned eps_count;
};

static int  __must_check ffs_epfiles_create(struct ffs_data *ffs);
static void ffs_epfiles_destroy(struct ffs_epfile *epfiles, unsigned count);

static struct dentry *
ffs_sb_create_file(struct super_block *sb, const char *name, void *data,
		   const struct file_operations *fops);

/* Devices management *******************************************************/

DEFINE_MUTEX(ffs_lock);
EXPORT_SYMBOL_GPL(ffs_lock);

static struct ffs_dev *_ffs_find_dev(const char *name);
static struct ffs_dev *_ffs_alloc_dev(void);
static void _ffs_free_dev(struct ffs_dev *dev);
static void *ffs_acquire_dev(const char *dev_name);
static void ffs_release_dev(struct ffs_data *ffs_data);
static int ffs_ready(struct ffs_data *ffs);
static void ffs_closed(struct ffs_data *ffs);

/* Misc helper functions ****************************************************/

static int ffs_mutex_lock(struct mutex *mutex, unsigned nonblock)
	__attribute__((warn_unused_result, nonnull));
static char *ffs_prepare_buffer(const char __user *buf, size_t len)
	__attribute__((warn_unused_result, nonnull));


/* Control file aka ep0 *****************************************************/

static void ffs_ep0_complete(struct usb_ep *ep, struct usb_request *req)
{
	struct ffs_data *ffs = req->context;

	complete(&ffs->ep0req_completion);
}

static int __ffs_ep0_queue_wait(struct ffs_data *ffs, char *data, size_t len)
	__releases(&ffs->ev.waitq.lock)
{
	struct usb_request *req = ffs->ep0req;
	int ret;

	req->zero     = len < le16_to_cpu(ffs->ev.setup.wLength);

	spin_unlock_irq(&ffs->ev.waitq.lock);

	req->buf      = data;
	req->length   = len;

	/*
	 * UDC layer requires to provide a buffer even for ZLP, but should
	 * not use it at all. Let's provide some poisoned pointer to catch
	 * possible bug in the driver.
	 */
	if (req->buf == NULL)
		req->buf = (void *)0xDEADBABE;

	reinit_completion(&ffs->ep0req_completion);

	ret = usb_ep_queue(ffs->gadget->ep0, req, GFP_ATOMIC);
	if (unlikely(ret < 0))
		return ret;

	ret = wait_for_completion_interruptible(&ffs->ep0req_completion);
	if (unlikely(ret)) {
		usb_ep_dequeue(ffs->gadget->ep0, req);
		return -EINTR;
	}

	ffs->setup_state = FFS_NO_SETUP;
	return req->status ? req->status : req->actual;
}

static int __ffs_ep0_stall(struct ffs_data *ffs)
{
	if (ffs->ev.can_stall) {
		pr_vdebug("ep0 stall\n");
		usb_ep_set_halt(ffs->gadget->ep0);
		ffs->setup_state = FFS_NO_SETUP;
		return -EL2HLT;
	} else {
		pr_debug("bogus ep0 stall!\n");
		return -ESRCH;
	}
}

static ssize_t ffs_ep0_write(struct file *file, const char __user *buf,
			     size_t len, loff_t *ptr)
{
	struct ffs_data *ffs = file->private_data;
	ssize_t ret;
	char *data;

	ENTER();

	/* Fast check if setup was canceled */
	if (ffs_setup_state_clear_cancelled(ffs) == FFS_SETUP_CANCELLED)
		return -EIDRM;

	/* Acquire mutex */
	ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
	if (unlikely(ret < 0))
		return ret;

	/* Check state */
	switch (ffs->state) {
	case FFS_READ_DESCRIPTORS:
	case FFS_READ_STRINGS:
		/* Copy data */
		if (unlikely(len < 16)) {
			ret = -EINVAL;
			break;
		}

		data = ffs_prepare_buffer(buf, len);
		if (IS_ERR(data)) {
			ret = PTR_ERR(data);
			break;
		}

		/* Handle data */
		if (ffs->state == FFS_READ_DESCRIPTORS) {
			pr_info("read descriptors\n");
			ret = __ffs_data_got_descs(ffs, data, len);
			if (unlikely(ret < 0))
				break;

			ffs->state = FFS_READ_STRINGS;
			ret = len;
		} else {
			pr_info("read strings\n");
			ret = __ffs_data_got_strings(ffs, data, len);
			if (unlikely(ret < 0))
				break;

			ret = ffs_epfiles_create(ffs);
			if (unlikely(ret)) {
				ffs->state = FFS_CLOSING;
				break;
			}

			ffs->state = FFS_ACTIVE;
			mutex_unlock(&ffs->mutex);

			ret = ffs_ready(ffs);
			if (unlikely(ret < 0)) {
				ffs->state = FFS_CLOSING;
				return ret;
			}

			return len;
		}
		break;

	case FFS_ACTIVE:
		data = NULL;
		/*
		 * We're called from user space, we can use _irq
		 * rather then _irqsave
		 */
		spin_lock_irq(&ffs->ev.waitq.lock);
		switch (ffs_setup_state_clear_cancelled(ffs)) {
		case FFS_SETUP_CANCELLED:
			ret = -EIDRM;
			goto done_spin;

		case FFS_NO_SETUP:
			ret = -ESRCH;
			goto done_spin;

		case FFS_SETUP_PENDING:
			break;
		}

		/* FFS_SETUP_PENDING */
		if (!(ffs->ev.setup.bRequestType & USB_DIR_IN)) {
			spin_unlock_irq(&ffs->ev.waitq.lock);
			ret = __ffs_ep0_stall(ffs);
			break;
		}

		/* FFS_SETUP_PENDING and not stall */
		len = min(len, (size_t)le16_to_cpu(ffs->ev.setup.wLength));

		spin_unlock_irq(&ffs->ev.waitq.lock);

		data = ffs_prepare_buffer(buf, len);
		if (IS_ERR(data)) {
			ret = PTR_ERR(data);
			break;
		}

		spin_lock_irq(&ffs->ev.waitq.lock);

		/*
		 * We are guaranteed to be still in FFS_ACTIVE state
		 * but the state of setup could have changed from
		 * FFS_SETUP_PENDING to FFS_SETUP_CANCELLED so we need
		 * to check for that.  If that happened we copied data
		 * from user space in vain but it's unlikely.
		 *
		 * For sure we are not in FFS_NO_SETUP since this is
		 * the only place FFS_SETUP_PENDING -> FFS_NO_SETUP
		 * transition can be performed and it's protected by
		 * mutex.
		 */
		if (ffs_setup_state_clear_cancelled(ffs) ==
		    FFS_SETUP_CANCELLED) {
			ret = -EIDRM;
done_spin:
			spin_unlock_irq(&ffs->ev.waitq.lock);
		} else {
			/* unlocks spinlock */
			ret = __ffs_ep0_queue_wait(ffs, data, len);
		}
		kfree(data);
		break;

	default:
		ret = -EBADFD;
		break;
	}

	mutex_unlock(&ffs->mutex);
	return ret;
}

/* Called with ffs->ev.waitq.lock and ffs->mutex held, both released on exit. */
static ssize_t __ffs_ep0_read_events(struct ffs_data *ffs, char __user *buf,
				     size_t n)
	__releases(&ffs->ev.waitq.lock)
{
	/*
	 * n cannot be bigger than ffs->ev.count, which cannot be bigger than
	 * size of ffs->ev.types array (which is four) so that's how much space
	 * we reserve.
	 */
	struct usb_functionfs_event events[ARRAY_SIZE(ffs->ev.types)];
	const size_t size = n * sizeof *events;
	unsigned i = 0;

	memset(events, 0, size);

	do {
		events[i].type = ffs->ev.types[i];
		if (events[i].type == FUNCTIONFS_SETUP) {
			events[i].u.setup = ffs->ev.setup;
			ffs->setup_state = FFS_SETUP_PENDING;
		}
	} while (++i < n);

	ffs->ev.count -= n;
	if (ffs->ev.count)
		memmove(ffs->ev.types, ffs->ev.types + n,
			ffs->ev.count * sizeof *ffs->ev.types);

	spin_unlock_irq(&ffs->ev.waitq.lock);
	mutex_unlock(&ffs->mutex);

	return unlikely(copy_to_user(buf, events, size)) ? -EFAULT : size;
}

static ssize_t ffs_ep0_read(struct file *file, char __user *buf,
			    size_t len, loff_t *ptr)
{
	struct ffs_data *ffs = file->private_data;
	char *data = NULL;
	size_t n;
	int ret;

	ENTER();

	/* Fast check if setup was canceled */
	if (ffs_setup_state_clear_cancelled(ffs) == FFS_SETUP_CANCELLED)
		return -EIDRM;

	/* Acquire mutex */
	ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
	if (unlikely(ret < 0))
		return ret;

	/* Check state */
	if (ffs->state != FFS_ACTIVE) {
		ret = -EBADFD;
		goto done_mutex;
	}

	/*
	 * We're called from user space, we can use _irq rather then
	 * _irqsave
	 */
	spin_lock_irq(&ffs->ev.waitq.lock);

	switch (ffs_setup_state_clear_cancelled(ffs)) {
	case FFS_SETUP_CANCELLED:
		ret = -EIDRM;
		break;

	case FFS_NO_SETUP:
		n = len / sizeof(struct usb_functionfs_event);
		if (unlikely(!n)) {
			ret = -EINVAL;
			break;
		}

		if ((file->f_flags & O_NONBLOCK) && !ffs->ev.count) {
			ret = -EAGAIN;
			break;
		}

		if (wait_event_interruptible_exclusive_locked_irq(ffs->ev.waitq,
							ffs->ev.count)) {
			ret = -EINTR;
			break;
		}

		/* unlocks spinlock */
		return __ffs_ep0_read_events(ffs, buf,
					     min(n, (size_t)ffs->ev.count));

	case FFS_SETUP_PENDING:
		if (ffs->ev.setup.bRequestType & USB_DIR_IN) {
			spin_unlock_irq(&ffs->ev.waitq.lock);
			ret = __ffs_ep0_stall(ffs);
			goto done_mutex;
		}

		len = min(len, (size_t)le16_to_cpu(ffs->ev.setup.wLength));

		spin_unlock_irq(&ffs->ev.waitq.lock);

		if (likely(len)) {
			data = kmalloc(len, GFP_KERNEL);
			if (unlikely(!data)) {
				ret = -ENOMEM;
				goto done_mutex;
			}
		}

		spin_lock_irq(&ffs->ev.waitq.lock);

		/* See ffs_ep0_write() */
		if (ffs_setup_state_clear_cancelled(ffs) ==
		    FFS_SETUP_CANCELLED) {
			ret = -EIDRM;
			break;
		}

		/* unlocks spinlock */
		ret = __ffs_ep0_queue_wait(ffs, data, len);
		if (likely(ret > 0) && unlikely(copy_to_user(buf, data, len)))
			ret = -EFAULT;
		goto done_mutex;

	default:
		ret = -EBADFD;
		break;
	}

	spin_unlock_irq(&ffs->ev.waitq.lock);
done_mutex:
	mutex_unlock(&ffs->mutex);
	kfree(data);
	return ret;
}

static int ffs_ep0_open(struct inode *inode, struct file *file)
{
	struct ffs_data *ffs = inode->i_private;

	ENTER();

	if (unlikely(ffs->state == FFS_CLOSING))
		return -EBUSY;

	file->private_data = ffs;
	ffs_data_opened(ffs);

	return 0;
}

static int ffs_ep0_release(struct inode *inode, struct file *file)
{
	struct ffs_data *ffs = file->private_data;

	ENTER();

	ffs_data_closed(ffs);

	return 0;
}

static long ffs_ep0_ioctl(struct file *file, unsigned code, unsigned long value)
{
	struct ffs_data *ffs = file->private_data;
	struct usb_gadget *gadget = ffs->gadget;
	long ret;

	ENTER();

	if (code == FUNCTIONFS_INTERFACE_REVMAP) {
		struct ffs_function *func = ffs->func;
		ret = func ? ffs_func_revmap_intf(func, value) : -ENODEV;
	} else if (gadget && gadget->ops->ioctl) {
		ret = gadget->ops->ioctl(gadget, code, value);
	} else {
		ret = -ENOTTY;
	}

	return ret;
}

static __poll_t ffs_ep0_poll(struct file *file, poll_table *wait)
{
	struct ffs_data *ffs = file->private_data;
	__poll_t mask = EPOLLWRNORM;
	int ret;

	poll_wait(file, &ffs->ev.waitq, wait);

	ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
	if (unlikely(ret < 0))
		return mask;

	switch (ffs->state) {
	case FFS_READ_DESCRIPTORS:
	case FFS_READ_STRINGS:
		mask |= EPOLLOUT;
		break;

	case FFS_ACTIVE:
		switch (ffs->setup_state) {
		case FFS_NO_SETUP:
			if (ffs->ev.count)
				mask |= EPOLLIN;
			break;

		case FFS_SETUP_PENDING:
		case FFS_SETUP_CANCELLED:
			mask |= (EPOLLIN | EPOLLOUT);
			break;
		}
	case FFS_CLOSING:
		break;
	case FFS_DEACTIVATED:
		break;
	}

	mutex_unlock(&ffs->mutex);

	return mask;
}

static const struct file_operations ffs_ep0_operations = {
	.llseek =	no_llseek,

	.open =		ffs_ep0_open,
	.write =	ffs_ep0_write,
	.read =		ffs_ep0_read,
	.release =	ffs_ep0_release,
	.unlocked_ioctl =	ffs_ep0_ioctl,
	.poll =		ffs_ep0_poll,
};


/* "Normal" endpoints operations ********************************************/

static void ffs_epfile_io_complete(struct usb_ep *_ep, struct usb_request *req)
{
	ENTER();
	if (likely(req->context)) {
		struct ffs_ep *ep = _ep->driver_data;
		ep->status = req->status ? req->status : req->actual;
		complete(req->context);
	}
}

static ssize_t ffs_copy_to_iter(void *data, int data_len, struct iov_iter *iter)
{
	ssize_t ret = copy_to_iter(data, data_len, iter);
	if (likely(ret == data_len))
		return ret;

	if (unlikely(iov_iter_count(iter)))
		return -EFAULT;

	/*
	 * Dear user space developer!
	 *
	 * TL;DR: To stop getting below error message in your kernel log, change
	 * user space code using functionfs to align read buffers to a max
	 * packet size.
	 *
	 * Some UDCs (e.g. dwc3) require request sizes to be a multiple of a max
	 * packet size.  When unaligned buffer is passed to functionfs, it
	 * internally uses a larger, aligned buffer so that such UDCs are happy.
	 *
	 * Unfortunately, this means that host may send more data than was
	 * requested in read(2) system call.  f_fs doesn’t know what to do with
	 * that excess data so it simply drops it.
	 *
	 * Was the buffer aligned in the first place, no such problem would
	 * happen.
	 *
	 * Data may be dropped only in AIO reads.  Synchronous reads are handled
	 * by splitting a request into multiple parts.  This splitting may still
	 * be a problem though so it’s likely best to align the buffer
	 * regardless of it being AIO or not..
	 *
	 * This only affects OUT endpoints, i.e. reading data with a read(2),
	 * aio_read(2) etc. system calls.  Writing data to an IN endpoint is not
	 * affected.
	 */
	pr_err("functionfs read size %d > requested size %zd, dropping excess data. "
	       "Align read buffer size to max packet size to avoid the problem.\n",
	       data_len, ret);

	return ret;
}

static void ffs_user_copy_worker(struct work_struct *work)
{
	struct ffs_io_data *io_data = container_of(work, struct ffs_io_data,
						   work);
	int ret = io_data->req->status ? io_data->req->status :
					 io_data->req->actual;
	bool kiocb_has_eventfd = io_data->kiocb->ki_flags & IOCB_EVENTFD;

	if (io_data->read && ret > 0) {
		use_mm(io_data->mm);
		ret = ffs_copy_to_iter(io_data->buf, ret, &io_data->data);
		unuse_mm(io_data->mm);
	}

	io_data->kiocb->ki_complete(io_data->kiocb, ret, ret);

	if (io_data->ffs->ffs_eventfd && !kiocb_has_eventfd)
		eventfd_signal(io_data->ffs->ffs_eventfd, 1);

	usb_ep_free_request(io_data->ep, io_data->req);

	if (io_data->read)
		kfree(io_data->to_free);
	kfree(io_data->buf);
	kfree(io_data);
}

static void ffs_epfile_async_io_complete(struct usb_ep *_ep,
					 struct usb_request *req)
{
	struct ffs_io_data *io_data = req->context;
	struct ffs_data *ffs = io_data->ffs;

	ENTER();

	INIT_WORK(&io_data->work, ffs_user_copy_worker);
	queue_work(ffs->io_completion_wq, &io_data->work);
}

static void __ffs_epfile_read_buffer_free(struct ffs_epfile *epfile)
{
	/*
	 * See comment in struct ffs_epfile for full read_buffer pointer
	 * synchronisation story.
	 */
	struct ffs_buffer *buf = xchg(&epfile->read_buffer, READ_BUFFER_DROP);
	if (buf && buf != READ_BUFFER_DROP)
		kfree(buf);
}

/* Assumes epfile->mutex is held. */
static ssize_t __ffs_epfile_read_buffered(struct ffs_epfile *epfile,
					  struct iov_iter *iter)
{
	/*
	 * Null out epfile->read_buffer so ffs_func_eps_disable does not free
	 * the buffer while we are using it.  See comment in struct ffs_epfile
	 * for full read_buffer pointer synchronisation story.
	 */
	struct ffs_buffer *buf = xchg(&epfile->read_buffer, NULL);
	ssize_t ret;
	if (!buf || buf == READ_BUFFER_DROP)
		return 0;

	ret = copy_to_iter(buf->data, buf->length, iter);
	if (buf->length == ret) {
		kfree(buf);
		return ret;
	}

	if (unlikely(iov_iter_count(iter))) {
		ret = -EFAULT;
	} else {
		buf->length -= ret;
		buf->data += ret;
	}

	if (cmpxchg(&epfile->read_buffer, NULL, buf))
		kfree(buf);

	return ret;
}

/* Assumes epfile->mutex is held. */
static ssize_t __ffs_epfile_read_data(struct ffs_epfile *epfile,
				      void *data, int data_len,
				      struct iov_iter *iter)
{
	struct ffs_buffer *buf;

	ssize_t ret = copy_to_iter(data, data_len, iter);
	if (likely(data_len == ret))
		return ret;

	if (unlikely(iov_iter_count(iter)))
		return -EFAULT;

	/* See ffs_copy_to_iter for more context. */
	pr_warn("functionfs read size %d > requested size %zd, splitting request into multiple reads.",
		data_len, ret);

	data_len -= ret;
	buf = kmalloc(sizeof(*buf) + data_len, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;
	buf->length = data_len;
	buf->data = buf->storage;
	memcpy(buf->storage, data + ret, data_len);

	/*
	 * At this point read_buffer is NULL or READ_BUFFER_DROP (if
	 * ffs_func_eps_disable has been called in the meanwhile).  See comment
	 * in struct ffs_epfile for full read_buffer pointer synchronisation
	 * story.
	 */
	if (unlikely(cmpxchg(&epfile->read_buffer, NULL, buf)))
		kfree(buf);

	return ret;
}

static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
{
	struct ffs_epfile *epfile = file->private_data;
	struct usb_request *req;
	struct ffs_ep *ep;
	char *data = NULL;
	ssize_t ret, data_len = -EINVAL;
	int halt;

	/* Are we still active? */
	if (WARN_ON(epfile->ffs->state != FFS_ACTIVE))
		return -ENODEV;

	/* Wait for endpoint to be enabled */
	ep = epfile->ep;
	if (!ep) {
		if (file->f_flags & O_NONBLOCK)
			return -EAGAIN;

		ret = wait_event_interruptible(
				epfile->ffs->wait, (ep = epfile->ep));
		if (ret)
			return -EINTR;
	}

	/* Do we halt? */
	halt = (!io_data->read == !epfile->in);
	if (halt && epfile->isoc)
		return -EINVAL;

	/* We will be using request and read_buffer */
	ret = ffs_mutex_lock(&epfile->mutex, file->f_flags & O_NONBLOCK);
	if (unlikely(ret))
		goto error;

	/* Allocate & copy */
	if (!halt) {
		struct usb_gadget *gadget;

		/*
		 * Do we have buffered data from previous partial read?  Check
		 * that for synchronous case only because we do not have
		 * facility to ‘wake up’ a pending asynchronous read and push
		 * buffered data to it which we would need to make things behave
		 * consistently.
		 */
		if (!io_data->aio && io_data->read) {
			ret = __ffs_epfile_read_buffered(epfile, &io_data->data);
			if (ret)
				goto error_mutex;
		}

		/*
		 * if we _do_ wait above, the epfile->ffs->gadget might be NULL
		 * before the waiting completes, so do not assign to 'gadget'
		 * earlier
		 */
		gadget = epfile->ffs->gadget;

		spin_lock_irq(&epfile->ffs->eps_lock);
		/* In the meantime, endpoint got disabled or changed. */
		if (epfile->ep != ep) {
			ret = -ESHUTDOWN;
			goto error_lock;
		}
		data_len = iov_iter_count(&io_data->data);
		/*
		 * Controller may require buffer size to be aligned to
		 * maxpacketsize of an out endpoint.
		 */
		if (io_data->read)
			data_len = usb_ep_align_maybe(gadget, ep->ep, data_len);
		spin_unlock_irq(&epfile->ffs->eps_lock);

		data = kmalloc(data_len, GFP_KERNEL);
		if (unlikely(!data)) {
			ret = -ENOMEM;
			goto error_mutex;
		}
		if (!io_data->read &&
		    !copy_from_iter_full(data, data_len, &io_data->data)) {
			ret = -EFAULT;
			goto error_mutex;
		}
	}

	spin_lock_irq(&epfile->ffs->eps_lock);

	if (epfile->ep != ep) {
		/* In the meantime, endpoint got disabled or changed. */
		ret = -ESHUTDOWN;
	} else if (halt) {
		ret = usb_ep_set_halt(ep->ep);
		if (!ret)
			ret = -EBADMSG;
	} else if (unlikely(data_len == -EINVAL)) {
		/*
		 * Sanity Check: even though data_len can't be used
		 * uninitialized at the time I write this comment, some
		 * compilers complain about this situation.
		 * In order to keep the code clean from warnings, data_len is
		 * being initialized to -EINVAL during its declaration, which
		 * means we can't rely on compiler anymore to warn no future
		 * changes won't result in data_len being used uninitialized.
		 * For such reason, we're adding this redundant sanity check
		 * here.
		 */
		WARN(1, "%s: data_len == -EINVAL\n", __func__);
		ret = -EINVAL;
	} else if (!io_data->aio) {
		DECLARE_COMPLETION_ONSTACK(done);
		bool interrupted = false;

		req = ep->req;
		req->buf      = data;
		req->length   = data_len;

		req->context  = &done;
		req->complete = ffs_epfile_io_complete;

		ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
		if (unlikely(ret < 0))
			goto error_lock;

		spin_unlock_irq(&epfile->ffs->eps_lock);

		if (unlikely(wait_for_completion_interruptible(&done))) {
			/*
			 * To avoid race condition with ffs_epfile_io_complete,
			 * dequeue the request first then check
			 * status. usb_ep_dequeue API should guarantee no race
			 * condition with req->complete callback.
			 */
			usb_ep_dequeue(ep->ep, req);
			interrupted = ep->status < 0;
		}

		if (interrupted)
			ret = -EINTR;
		else if (io_data->read && ep->status > 0)
			ret = __ffs_epfile_read_data(epfile, data, ep->status,
						     &io_data->data);
		else
			ret = ep->status;
		goto error_mutex;
	} else if (!(req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC))) {
		ret = -ENOMEM;
	} else {
		req->buf      = data;
		req->length   = data_len;

		io_data->buf = data;
		io_data->ep = ep->ep;
		io_data->req = req;
		io_data->ffs = epfile->ffs;

		req->context  = io_data;
		req->complete = ffs_epfile_async_io_complete;

		ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
		if (unlikely(ret)) {
			usb_ep_free_request(ep->ep, req);
			goto error_lock;
		}

		ret = -EIOCBQUEUED;
		/*
		 * Do not kfree the buffer in this function.  It will be freed
		 * by ffs_user_copy_worker.
		 */
		data = NULL;
	}

error_lock:
	spin_unlock_irq(&epfile->ffs->eps_lock);
error_mutex:
	mutex_unlock(&epfile->mutex);
error:
	kfree(data);
	return ret;
}

static int
ffs_epfile_open(struct inode *inode, struct file *file)
{
	struct ffs_epfile *epfile = inode->i_private;

	ENTER();

	if (WARN_ON(epfile->ffs->state != FFS_ACTIVE))
		return -ENODEV;

	file->private_data = epfile;
	ffs_data_opened(epfile->ffs);

	return 0;
}

static int ffs_aio_cancel(struct kiocb *kiocb)
{
	struct ffs_io_data *io_data = kiocb->private;
	struct ffs_epfile *epfile = kiocb->ki_filp->private_data;
	int value;

	ENTER();

	spin_lock_irq(&epfile->ffs->eps_lock);

	if (likely(io_data && io_data->ep && io_data->req))
		value = usb_ep_dequeue(io_data->ep, io_data->req);
	else
		value = -EINVAL;

	spin_unlock_irq(&epfile->ffs->eps_lock);

	return value;
}

static ssize_t ffs_epfile_write_iter(struct kiocb *kiocb, struct iov_iter *from)
{
	struct ffs_io_data io_data, *p = &io_data;
	ssize_t res;

	ENTER();

	if (!is_sync_kiocb(kiocb)) {
		p = kmalloc(sizeof(io_data), GFP_KERNEL);
		if (unlikely(!p))
			return -ENOMEM;
		p->aio = true;
	} else {
		p->aio = false;
	}

	p->read = false;
	p->kiocb = kiocb;
	p->data = *from;
	p->mm = current->mm;

	kiocb->private = p;

	if (p->aio)
		kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);

	res = ffs_epfile_io(kiocb->ki_filp, p);
	if (res == -EIOCBQUEUED)
		return res;
	if (p->aio)
		kfree(p);
	else
		*from = p->data;
	return res;
}

static ssize_t ffs_epfile_read_iter(struct kiocb *kiocb, struct iov_iter *to)
{
	struct ffs_io_data io_data, *p = &io_data;
	ssize_t res;

	ENTER();

	if (!is_sync_kiocb(kiocb)) {
		p = kmalloc(sizeof(io_data), GFP_KERNEL);
		if (unlikely(!p))
			return -ENOMEM;
		p->aio = true;
	} else {
		p->aio = false;
	}

	p->read = true;
	p->kiocb = kiocb;
	if (p->aio) {
		p->to_free = dup_iter(&p->data, to, GFP_KERNEL);
		if (!p->to_free) {
			kfree(p);
			return -ENOMEM;
		}
	} else {
		p->data = *to;
		p->to_free = NULL;
	}
	p->mm = current->mm;

	kiocb->private = p;

	if (p->aio)
		kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);

	res = ffs_epfile_io(kiocb->ki_filp, p);
	if (res == -EIOCBQUEUED)
		return res;

	if (p->aio) {
		kfree(p->to_free);
		kfree(p);
	} else {
		*to = p->data;
	}
	return res;
}

static int
ffs_epfile_release(struct inode *inode, struct file *file)
{
	struct ffs_epfile *epfile = inode->i_private;

	ENTER();

	__ffs_epfile_read_buffer_free(epfile);
	ffs_data_closed(epfile->ffs);

	return 0;
}

static long ffs_epfile_ioctl(struct file *file, unsigned code,
			     unsigned long value)
{
	struct ffs_epfile *epfile = file->private_data;
	struct ffs_ep *ep;
	int ret;

	ENTER();

	if (WARN_ON(epfile->ffs->state != FFS_ACTIVE))
		return -ENODEV;

	/* Wait for endpoint to be enabled */
	ep = epfile->ep;
	if (!ep) {
		if (file->f_flags & O_NONBLOCK)
			return -EAGAIN;

		ret = wait_event_interruptible(
				epfile->ffs->wait, (ep = epfile->ep));
		if (ret)
			return -EINTR;
	}

	spin_lock_irq(&epfile->ffs->eps_lock);

	/* In the meantime, endpoint got disabled or changed. */
	if (epfile->ep != ep) {
		spin_unlock_irq(&epfile->ffs->eps_lock);
		return -ESHUTDOWN;
	}

	switch (code) {
	case FUNCTIONFS_FIFO_STATUS:
		ret = usb_ep_fifo_status(epfile->ep->ep);
		break;
	case FUNCTIONFS_FIFO_FLUSH:
		usb_ep_fifo_flush(epfile->ep->ep);
		ret = 0;
		break;
	case FUNCTIONFS_CLEAR_HALT:
		ret = usb_ep_clear_halt(epfile->ep->ep);
		break;
	case FUNCTIONFS_ENDPOINT_REVMAP:
		ret = epfile->ep->num;
		break;
	case FUNCTIONFS_ENDPOINT_DESC:
	{
		int desc_idx;
		struct usb_endpoint_descriptor *desc;

		switch (epfile->ffs->gadget->speed) {
		case USB_SPEED_SUPER:
			desc_idx = 2;
			break;
		case USB_SPEED_HIGH:
			desc_idx = 1;
			break;
		default:
			desc_idx = 0;
		}
		desc = epfile->ep->descs[desc_idx];

		spin_unlock_irq(&epfile->ffs->eps_lock);
		ret = copy_to_user((void __user *)value, desc, desc->bLength);
		if (ret)
			ret = -EFAULT;
		return ret;
	}
	default:
		ret = -ENOTTY;
	}
	spin_unlock_irq(&epfile->ffs->eps_lock);

	return ret;
}

static const struct file_operations ffs_epfile_operations = {
	.llseek =	no_llseek,

	.open =		ffs_epfile_open,
	.write_iter =	ffs_epfile_write_iter,
	.read_iter =	ffs_epfile_read_iter,
	.release =	ffs_epfile_release,
	.unlocked_ioctl =	ffs_epfile_ioctl,
};


/* File system and super block operations ***********************************/

/*
 * Mounting the file system creates a controller file, used first for
 * function configuration then later for event monitoring.
 */

static struct inode *__must_check
ffs_sb_make_inode(struct super_block *sb, void *data,
		  const struct file_operations *fops,
		  const struct inode_operations *iops,
		  struct ffs_file_perms *perms)
{
	struct inode *inode;

	ENTER();

	inode = new_inode(sb);

	if (likely(inode)) {
		struct timespec ts = current_time(inode);

		inode->i_ino	 = get_next_ino();
		inode->i_mode    = perms->mode;
		inode->i_uid     = perms->uid;
		inode->i_gid     = perms->gid;
		inode->i_atime   = ts;
		inode->i_mtime   = ts;
		inode->i_ctime   = ts;
		inode->i_private = data;
		if (fops)
			inode->i_fop = fops;
		if (iops)
			inode->i_op  = iops;
	}

	return inode;
}

/* Create "regular" file */
static struct dentry *ffs_sb_create_file(struct super_block *sb,
					const char *name, void *data,
					const struct file_operations *fops)
{
	struct ffs_data	*ffs = sb->s_fs_info;
	struct dentry	*dentry;
	struct inode	*inode;

	ENTER();

	dentry = d_alloc_name(sb->s_root, name);
	if (unlikely(!dentry))
		return NULL;

	inode = ffs_sb_make_inode(sb, data, fops, NULL, &ffs->file_perms);
	if (unlikely(!inode)) {
		dput(dentry);
		return NULL;
	}

	d_add(dentry, inode);
	return dentry;
}

/* Super block */
static const struct super_operations ffs_sb_operations = {
	.statfs =	simple_statfs,
	.drop_inode =	generic_delete_inode,
};

struct ffs_sb_fill_data {
	struct ffs_file_perms perms;
	umode_t root_mode;
	const char *dev_name;
	bool no_disconnect;
	struct ffs_data *ffs_data;
};

static int ffs_sb_fill(struct super_block *sb, void *_data, int silent)
{
	struct ffs_sb_fill_data *data = _data;
	struct inode	*inode;
	struct ffs_data	*ffs = data->ffs_data;

	ENTER();

	ffs->sb              = sb;
	data->ffs_data       = NULL;
	sb->s_fs_info        = ffs;
	sb->s_blocksize      = PAGE_SIZE;
	sb->s_blocksize_bits = PAGE_SHIFT;
	sb->s_magic          = FUNCTIONFS_MAGIC;
	sb->s_op             = &ffs_sb_operations;
	sb->s_time_gran      = 1;

	/* Root inode */
	data->perms.mode = data->root_mode;
	inode = ffs_sb_make_inode(sb, NULL,
				  &simple_dir_operations,
				  &simple_dir_inode_operations,
				  &data->perms);
	sb->s_root = d_make_root(inode);
	if (unlikely(!sb->s_root))
		return -ENOMEM;

	/* EP0 file */
	if (unlikely(!ffs_sb_create_file(sb, "ep0", ffs,
					 &ffs_ep0_operations)))
		return -ENOMEM;

	return 0;
}

static int ffs_fs_parse_opts(struct ffs_sb_fill_data *data, char *opts)
{
	ENTER();

	if (!opts || !*opts)
		return 0;

	for (;;) {
		unsigned long value;
		char *eq, *comma;

		/* Option limit */
		comma = strchr(opts, ',');
		if (comma)
			*comma = 0;

		/* Value limit */
		eq = strchr(opts, '=');
		if (unlikely(!eq)) {
			pr_err("'=' missing in %s\n", opts);
			return -EINVAL;
		}
		*eq = 0;

		/* Parse value */
		if (kstrtoul(eq + 1, 0, &value)) {
			pr_err("%s: invalid value: %s\n", opts, eq + 1);
			return -EINVAL;
		}

		/* Interpret option */
		switch (eq - opts) {
		case 13:
			if (!memcmp(opts, "no_disconnect", 13))
				data->no_disconnect = !!value;
			else
				goto invalid;
			break;
		case 5:
			if (!memcmp(opts, "rmode", 5))
				data->root_mode  = (value & 0555) | S_IFDIR;
			else if (!memcmp(opts, "fmode", 5))
				data->perms.mode = (value & 0666) | S_IFREG;
			else
				goto invalid;
			break;

		case 4:
			if (!memcmp(opts, "mode", 4)) {
				data->root_mode  = (value & 0555) | S_IFDIR;
				data->perms.mode = (value & 0666) | S_IFREG;
			} else {
				goto invalid;
			}
			break;

		case 3:
			if (!memcmp(opts, "uid", 3)) {
				data->perms.uid = make_kuid(current_user_ns(), value);
				if (!uid_valid(data->perms.uid)) {
					pr_err("%s: unmapped value: %lu\n", opts, value);
					return -EINVAL;
				}
			} else if (!memcmp(opts, "gid", 3)) {
				data->perms.gid = make_kgid(current_user_ns(), value);
				if (!gid_valid(data->perms.gid)) {
					pr_err("%s: unmapped value: %lu\n", opts, value);
					return -EINVAL;
				}
			} else {
				goto invalid;
			}
			break;

		default:
invalid:
			pr_err("%s: invalid option\n", opts);
			return -EINVAL;
		}

		/* Next iteration */
		if (!comma)
			break;
		opts = comma + 1;
	}

	return 0;
}

/* "mount -t functionfs dev_name /dev/function" ends up here */

static struct dentry *
ffs_fs_mount(struct file_system_type *t, int flags,
	      const char *dev_name, void *opts)
{
	struct ffs_sb_fill_data data = {
		.perms = {
			.mode = S_IFREG | 0600,
			.uid = GLOBAL_ROOT_UID,
			.gid = GLOBAL_ROOT_GID,
		},
		.root_mode = S_IFDIR | 0500,
		.no_disconnect = false,
	};
	struct dentry *rv;
	int ret;
	void *ffs_dev;
	struct ffs_data	*ffs;

	ENTER();

	ret = ffs_fs_parse_opts(&data, opts);
	if (unlikely(ret < 0))
		return ERR_PTR(ret);

	ffs = ffs_data_new(dev_name);
	if (unlikely(!ffs))
		return ERR_PTR(-ENOMEM);
	ffs->file_perms = data.perms;
	ffs->no_disconnect = data.no_disconnect;

	ffs->dev_name = kstrdup(dev_name, GFP_KERNEL);
	if (unlikely(!ffs->dev_name)) {
		ffs_data_put(ffs);
		return ERR_PTR(-ENOMEM);
	}

	ffs_dev = ffs_acquire_dev(dev_name);
	if (IS_ERR(ffs_dev)) {
		ffs_data_put(ffs);
		return ERR_CAST(ffs_dev);
	}
	ffs->private_data = ffs_dev;
	data.ffs_data = ffs;

	rv = mount_nodev(t, flags, &data, ffs_sb_fill);
	if (IS_ERR(rv) && data.ffs_data) {
		ffs_release_dev(data.ffs_data);
		ffs_data_put(data.ffs_data);
	}
	return rv;
}

static void
ffs_fs_kill_sb(struct super_block *sb)
{
	ENTER();

	kill_litter_super(sb);
	if (sb->s_fs_info) {
		ffs_release_dev(sb->s_fs_info);
		ffs_data_closed(sb->s_fs_info);
		ffs_data_put(sb->s_fs_info);
	}
}

static struct file_system_type ffs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "functionfs",
	.mount		= ffs_fs_mount,
	.kill_sb	= ffs_fs_kill_sb,
};
MODULE_ALIAS_FS("functionfs");


/* Driver's main init/cleanup functions *************************************/

static int functionfs_init(void)
{
	int ret;

	ENTER();

	ret = register_filesystem(&ffs_fs_type);
	if (likely(!ret))
		pr_info("file system registered\n");
	else
		pr_err("failed registering file system (%d)\n", ret);

	return ret;
}

static void functionfs_cleanup(void)
{
	ENTER();

	pr_info("unloading\n");
	unregister_filesystem(&ffs_fs_type);
}


/* ffs_data and ffs_function construction and destruction code **************/

static void ffs_data_clear(struct ffs_data *ffs);
static void ffs_data_reset(struct ffs_data *ffs);

static void ffs_data_get(struct ffs_data *ffs)
{
	ENTER();

	refcount_inc(&ffs->ref);
}

static void ffs_data_opened(struct ffs_data *ffs)
{
	ENTER();

	refcount_inc(&ffs->ref);
	if (atomic_add_return(1, &ffs->opened) == 1 &&
			ffs->state == FFS_DEACTIVATED) {
		ffs->state = FFS_CLOSING;
		ffs_data_reset(ffs);
	}
}

static void ffs_data_put(struct ffs_data *ffs)
{
	ENTER();

	if (unlikely(refcount_dec_and_test(&ffs->ref))) {
		pr_info("%s(): freeing\n", __func__);
		ffs_data_clear(ffs);
		BUG_ON(waitqueue_active(&ffs->ev.waitq) ||
		       waitqueue_active(&ffs->ep0req_completion.wait) ||
		       waitqueue_active(&ffs->wait));
		destroy_workqueue(ffs->io_completion_wq);
		kfree(ffs->dev_name);
		kfree(ffs);
	}
}

static void ffs_data_closed(struct ffs_data *ffs)
{
	ENTER();

	if (atomic_dec_and_test(&ffs->opened)) {
		if (ffs->no_disconnect) {
			ffs->state = FFS_DEACTIVATED;
			if (ffs->epfiles) {
				ffs_epfiles_destroy(ffs->epfiles,
						   ffs->eps_count);
				ffs->epfiles = NULL;
			}
			if (ffs->setup_state == FFS_SETUP_PENDING)
				__ffs_ep0_stall(ffs);
		} else {
			ffs->state = FFS_CLOSING;
			ffs_data_reset(ffs);
		}
	}
	if (atomic_read(&ffs->opened) < 0) {
		ffs->state = FFS_CLOSING;
		ffs_data_reset(ffs);
	}

	ffs_data_put(ffs);
}

static struct ffs_data *ffs_data_new(const char *dev_name)
{
	struct ffs_data *ffs = kzalloc(sizeof *ffs, GFP_KERNEL);
	if (unlikely(!ffs))
		return NULL;

	ENTER();

	ffs->io_completion_wq = alloc_ordered_workqueue("%s", 0, dev_name);
	if (!ffs->io_completion_wq) {
		kfree(ffs);
		return NULL;
	}

	refcount_set(&ffs->ref, 1);
	atomic_set(&ffs->opened, 0);
	ffs->state = FFS_READ_DESCRIPTORS;
	mutex_init(&ffs->mutex);
	spin_lock_init(&ffs->eps_lock);
	init_waitqueue_head(&ffs->ev.waitq);
	init_waitqueue_head(&ffs->wait);
	init_completion(&ffs->ep0req_completion);

	/* XXX REVISIT need to update it in some places, or do we? */
	ffs->ev.can_stall = 1;

	return ffs;
}

static void ffs_data_clear(struct ffs_data *ffs)
{
	ENTER();

	ffs_closed(ffs);

	BUG_ON(ffs->gadget);

	if (ffs->epfiles)
		ffs_epfiles_destroy(ffs->epfiles, ffs->eps_count);

	if (ffs->ffs_eventfd)
		eventfd_ctx_put(ffs->ffs_eventfd);

	kfree(ffs->raw_descs_data);
	kfree(ffs->raw_strings);
	kfree(ffs->stringtabs);
}

static void ffs_data_reset(struct ffs_data *ffs)
{
	ENTER();

	ffs_data_clear(ffs);

	ffs->epfiles = NULL;
	ffs->raw_descs_data = NULL;
	ffs->raw_descs = NULL;
	ffs->raw_strings = NULL;
	ffs->stringtabs = NULL;

	ffs->raw_descs_length = 0;
	ffs->fs_descs_count = 0;
	ffs->hs_descs_count = 0;
	ffs->ss_descs_count = 0;

	ffs->strings_count = 0;
	ffs->interfaces_count = 0;
	ffs->eps_count = 0;

	ffs->ev.count = 0;

	ffs->state = FFS_READ_DESCRIPTORS;
	ffs->setup_state = FFS_NO_SETUP;
	ffs->flags = 0;
}


static int functionfs_bind(struct ffs_data *ffs, struct usb_composite_dev *cdev)
{
	struct usb_gadget_strings **lang;
	int first_id;

	ENTER();

	if (WARN_ON(ffs->state != FFS_ACTIVE
		 || test_and_set_bit(FFS_FL_BOUND, &ffs->flags)))
		return -EBADFD;

	first_id = usb_string_ids_n(cdev, ffs->strings_count);
	if (unlikely(first_id < 0))
		return first_id;

	ffs->ep0req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
	if (unlikely(!ffs->ep0req))
		return -ENOMEM;
	ffs->ep0req->complete = ffs_ep0_complete;
	ffs->ep0req->context = ffs;

	lang = ffs->stringtabs;
	if (lang) {
		for (; *lang; ++lang) {
			struct usb_string *str = (*lang)->strings;
			int id = first_id;
			for (; str->s; ++id, ++str)
				str->id = id;
		}
	}

	ffs->gadget = cdev->gadget;
	ffs_data_get(ffs);
	return 0;
}

static void functionfs_unbind(struct ffs_data *ffs)
{
	ENTER();

	if (!WARN_ON(!ffs->gadget)) {
		usb_ep_free_request(ffs->gadget->ep0, ffs->ep0req);
		ffs->ep0req = NULL;
		ffs->gadget = NULL;
		clear_bit(FFS_FL_BOUND, &ffs->flags);
		ffs_data_put(ffs);
	}
}

static int ffs_epfiles_create(struct ffs_data *ffs)
{
	struct ffs_epfile *epfile, *epfiles;
	unsigned i, count;

	ENTER();

	count = ffs->eps_count;
	epfiles = kcalloc(count, sizeof(*epfiles), GFP_KERNEL);
	if (!epfiles)
		return -ENOMEM;

	epfile = epfiles;
	for (i = 1; i <= count; ++i, ++epfile) {
		epfile->ffs = ffs;
		mutex_init(&epfile->mutex);
		if (ffs->user_flags & FUNCTIONFS_VIRTUAL_ADDR)
			sprintf(epfile->name, "ep%02x", ffs->eps_addrmap[i]);
		else
			sprintf(epfile->name, "ep%u", i);
		epfile->dentry = ffs_sb_create_file(ffs->sb, epfile->name,
						 epfile,
						 &ffs_epfile_operations);
		if (unlikely(!epfile->dentry)) {
			ffs_epfiles_destroy(epfiles, i - 1);
			return -ENOMEM;
		}
	}

	ffs->epfiles = epfiles;
	return 0;
}

static void ffs_epfiles_destroy(struct ffs_epfile *epfiles, unsigned count)
{
	struct ffs_epfile *epfile = epfiles;

	ENTER();

	for (; count; --count, ++epfile) {
		BUG_ON(mutex_is_locked(&epfile->mutex));
		if (epfile->dentry) {
			d_delete(epfile->dentry);
			dput(epfile->dentry);
			epfile->dentry = NULL;
		}
	}

	kfree(epfiles);
}

static void ffs_func_eps_disable(struct ffs_function *func)
{
	struct ffs_ep *ep         = func->eps;
	struct ffs_epfile *epfile = func->ffs->epfiles;
	unsigned count            = func->ffs->eps_count;
	unsigned long flags;

	spin_lock_irqsave(&func->ffs->eps_lock, flags);
	while (count--) {
		/* pending requests get nuked */
		if (likely(ep->ep))
			usb_ep_disable(ep->ep);
		++ep;

		if (epfile) {
			epfile->ep = NULL;
			__ffs_epfile_read_buffer_free(epfile);
			++epfile;
		}
	}
	spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
}

static int ffs_func_eps_enable(struct ffs_function *func)
{
	struct ffs_data *ffs      = func->ffs;
	struct ffs_ep *ep         = func->eps;
	struct ffs_epfile *epfile = ffs->epfiles;
	unsigned count            = ffs->eps_count;
	unsigned long flags;
	int ret = 0;

	spin_lock_irqsave(&func->ffs->eps_lock, flags);
	while(count--) {
		ep->ep->driver_data = ep;

		ret = config_ep_by_speed(func->gadget, &func->function, ep->ep);
		if (ret) {
			pr_err("%s: config_ep_by_speed(%s) returned %d\n",
					__func__, ep->ep->name, ret);
			break;
		}

		ret = usb_ep_enable(ep->ep);
		if (likely(!ret)) {
			epfile->ep = ep;
			epfile->in = usb_endpoint_dir_in(ep->ep->desc);
			epfile->isoc = usb_endpoint_xfer_isoc(ep->ep->desc);
		} else {
			break;
		}

		++ep;
		++epfile;
	}

	wake_up_interruptible(&ffs->wait);
	spin_unlock_irqrestore(&func->ffs->eps_lock, flags);

	return ret;
}


/* Parsing and building descriptors and strings *****************************/

/*
 * This validates if data pointed by data is a valid USB descriptor as
 * well as record how many interfaces, endpoints and strings are
 * required by given configuration.  Returns address after the
 * descriptor or NULL if data is invalid.
 */

enum ffs_entity_type {
	FFS_DESCRIPTOR, FFS_INTERFACE, FFS_STRING, FFS_ENDPOINT
};

enum ffs_os_desc_type {
	FFS_OS_DESC, FFS_OS_DESC_EXT_COMPAT, FFS_OS_DESC_EXT_PROP
};

typedef int (*ffs_entity_callback)(enum ffs_entity_type entity,
				   u8 *valuep,
				   struct usb_descriptor_header *desc,
				   void *priv);

typedef int (*ffs_os_desc_callback)(enum ffs_os_desc_type entity,
				    struct usb_os_desc_header *h, void *data,
				    unsigned len, void *priv);

static int __must_check ffs_do_single_desc(char *data, unsigned len,
					   ffs_entity_callback entity,
					   void *priv)
{
	struct usb_descriptor_header *_ds = (void *)data;
	u8 length;
	int ret;

	ENTER();

	/* At least two bytes are required: length and type */
	if (len < 2) {
		pr_vdebug("descriptor too short\n");
		return -EINVAL;
	}

	/* If we have at least as many bytes as the descriptor takes? */
	length = _ds->bLength;
	if (len < length) {
		pr_vdebug("descriptor longer then available data\n");
		return -EINVAL;
	}

#define __entity_check_INTERFACE(val)  1
#define __entity_check_STRING(val)     (val)
#define __entity_check_ENDPOINT(val)   ((val) & USB_ENDPOINT_NUMBER_MASK)
#define __entity(type, val) do {					\
		pr_vdebug("entity " #type "(%02x)\n", (val));		\
		if (unlikely(!__entity_check_ ##type(val))) {		\
			pr_vdebug("invalid entity's value\n");		\
			return -EINVAL;					\
		}							\
		ret = entity(FFS_ ##type, &val, _ds, priv);		\
		if (unlikely(ret < 0)) {				\
			pr_debug("entity " #type "(%02x); ret = %d\n",	\
				 (val), ret);				\
			return ret;					\
		}							\
	} while (0)

	/* Parse descriptor depending on type. */
	switch (_ds->bDescriptorType) {
	case USB_DT_DEVICE:
	case USB_DT_CONFIG:
	case USB_DT_STRING:
	case USB_DT_DEVICE_QUALIFIER:
		/* function can't have any of those */
		pr_vdebug("descriptor reserved for gadget: %d\n",
		      _ds->bDescriptorType);
		return -EINVAL;

	case USB_DT_INTERFACE: {
		struct usb_interface_descriptor *ds = (void *)_ds;
		pr_vdebug("interface descriptor\n");
		if (length != sizeof *ds)
			goto inv_length;

		__entity(INTERFACE, ds->bInterfaceNumber);
		if (ds->iInterface)
			__entity(STRING, ds->iInterface);
	}
		break;

	case USB_DT_ENDPOINT: {
		struct usb_endpoint_descriptor *ds = (void *)_ds;
		pr_vdebug("endpoint descriptor\n");
		if (length != USB_DT_ENDPOINT_SIZE &&
		    length != USB_DT_ENDPOINT_AUDIO_SIZE)
			goto inv_length;
		__entity(ENDPOINT, ds->bEndpointAddress);
	}
		break;

	case HID_DT_HID:
		pr_vdebug("hid descriptor\n");
		if (length != sizeof(struct hid_descriptor))
			goto inv_length;
		break;

	case USB_DT_OTG:
		if (length != sizeof(struct usb_otg_descriptor))
			goto inv_length;
		break;

	case USB_DT_INTERFACE_ASSOCIATION: {
		struct usb_interface_assoc_descriptor *ds = (void *)_ds;
		pr_vdebug("interface association descriptor\n");
		if (length != sizeof *ds)
			goto inv_length;
		if (ds->iFunction)
			__entity(STRING, ds->iFunction);
	}
		break;

	case USB_DT_SS_ENDPOINT_COMP:
		pr_vdebug("EP SS companion descriptor\n");
		if (length != sizeof(struct usb_ss_ep_comp_descriptor))
			goto inv_length;
		break;

	case USB_DT_OTHER_SPEED_CONFIG:
	case USB_DT_INTERFACE_POWER:
	case USB_DT_DEBUG:
	case USB_DT_SECURITY:
	case USB_DT_CS_RADIO_CONTROL:
		/* TODO */
		pr_vdebug("unimplemented descriptor: %d\n", _ds->bDescriptorType);
		return -EINVAL;

	default:
		/* We should never be here */
		pr_vdebug("unknown descriptor: %d\n", _ds->bDescriptorType);
		return -EINVAL;

inv_length:
		pr_vdebug("invalid length: %d (descriptor %d)\n",
			  _ds->bLength, _ds->bDescriptorType);
		return -EINVAL;
	}

#undef __entity
#undef __entity_check_DESCRIPTOR
#undef __entity_check_INTERFACE
#undef __entity_check_STRING
#undef __entity_check_ENDPOINT

	return length;
}

static int __must_check ffs_do_descs(unsigned count, char *data, unsigned len,
				     ffs_entity_callback entity, void *priv)
{
	const unsigned _len = len;
	unsigned long num = 0;

	ENTER();

	for (;;) {
		int ret;

		if (num == count)
			data = NULL;

		/* Record "descriptor" entity */
		ret = entity(FFS_DESCRIPTOR, (u8 *)num, (void *)data, priv);
		if (unlikely(ret < 0)) {
			pr_debug("entity DESCRIPTOR(%02lx); ret = %d\n",
				 num, ret);
			return ret;
		}

		if (!data)
			return _len - len;

		ret = ffs_do_single_desc(data, len, entity, priv);
		if (unlikely(ret < 0)) {
			pr_debug("%s returns %d\n", __func__, ret);
			return ret;
		}

		len -= ret;
		data += ret;
		++num;
	}
}

static int __ffs_data_do_entity(enum ffs_entity_type type,
				u8 *valuep, struct usb_descriptor_header *desc,
				void *priv)
{
	struct ffs_desc_helper *helper = priv;
	struct usb_endpoint_descriptor *d;

	ENTER();

	switch (type) {
	case FFS_DESCRIPTOR:
		break;

	case FFS_INTERFACE:
		/*
		 * Interfaces are indexed from zero so if we
		 * encountered interface "n" then there are at least
		 * "n+1" interfaces.
		 */
		if (*valuep >= helper->interfaces_count)
			helper->interfaces_count = *valuep + 1;
		break;

	case FFS_STRING:
		/*
		 * Strings are indexed from 1 (0 is reserved
		 * for languages list)
		 */
		if (*valuep > helper->ffs->strings_count)
			helper->ffs->strings_count = *valuep;
		break;

	case FFS_ENDPOINT:
		d = (void *)desc;
		helper->eps_count++;
		if (helper->eps_count >= FFS_MAX_EPS_COUNT)
			return -EINVAL;
		/* Check if descriptors for any speed were already parsed */
		if (!helper->ffs->eps_count && !helper->ffs->interfaces_count)
			helper->ffs->eps_addrmap[helper->eps_count] =
				d->bEndpointAddress;
		else if (helper->ffs->eps_addrmap[helper->eps_count] !=
				d->bEndpointAddress)
			return -EINVAL;
		break;
	}

	return 0;
}

static int __ffs_do_os_desc_header(enum ffs_os_desc_type *next_type,
				   struct usb_os_desc_header *desc)
{
	u16 bcd_version = le16_to_cpu(desc->bcdVersion);
	u16 w_index = le16_to_cpu(desc->wIndex);

	if (bcd_version != 1) {
		pr_vdebug("unsupported os descriptors version: %d",
			  bcd_version);
		return -EINVAL;
	}
	switch (w_index) {
	case 0x4:
		*next_type = FFS_OS_DESC_EXT_COMPAT;
		break;
	case 0x5:
		*next_type = FFS_OS_DESC_EXT_PROP;
		break;
	default:
		pr_vdebug("unsupported os descriptor type: %d", w_index);
		return -EINVAL;
	}

	return sizeof(*desc);
}

/*
 * Process all extended compatibility/extended property descriptors
 * of a feature descriptor
 */
static int __must_check ffs_do_single_os_desc(char *data, unsigned len,
					      enum ffs_os_desc_type type,
					      u16 feature_count,
					      ffs_os_desc_callback entity,
					      void *priv,
					      struct usb_os_desc_header *h)
{
	int ret;
	const unsigned _len = len;

	ENTER();

	/* loop over all ext compat/ext prop descriptors */
	while (feature_count--) {
		ret = entity(type, h, data, len, priv);
		if (unlikely(ret < 0)) {
			pr_debug("bad OS descriptor, type: %d\n", type);
			return ret;
		}
		data += ret;
		len -= ret;
	}
	return _len - len;
}

/* Process a number of complete Feature Descriptors (Ext Compat or Ext Prop) */
static int __must_check ffs_do_os_descs(unsigned count,
					char *data, unsigned len,
					ffs_os_desc_callback entity, void *priv)
{
	const unsigned _len = len;
	unsigned long num = 0;

	ENTER();

	for (num = 0; num < count; ++num) {
		int ret;
		enum ffs_os_desc_type type;
		u16 feature_count;
		struct usb_os_desc_header *desc = (void *)data;

		if (len < sizeof(*desc))
			return -EINVAL;

		/*
		 * Record "descriptor" entity.
		 * Process dwLength, bcdVersion, wIndex, get b/wCount.
		 * Move the data pointer to the beginning of extended
		 * compatibilities proper or extended properties proper
		 * portions of the data
		 */
		if (le32_to_cpu(desc->dwLength) > len)
			return -EINVAL;

		ret = __ffs_do_os_desc_header(&type, desc);
		if (unlikely(ret < 0)) {
			pr_debug("entity OS_DESCRIPTOR(%02lx); ret = %d\n",
				 num, ret);
			return ret;
		}
		/*
		 * 16-bit hex "?? 00" Little Endian looks like 8-bit hex "??"
		 */
		feature_count = le16_to_cpu(desc->wCount);
		if (type == FFS_OS_DESC_EXT_COMPAT &&
		    (feature_count > 255 || desc->Reserved))
				return -EINVAL;
		len -= ret;
		data += ret;

		/*
		 * Process all function/property descriptors
		 * of this Feature Descriptor
		 */
		ret = ffs_do_single_os_desc(data, len, type,
					    feature_count, entity, priv, desc);
		if (unlikely(ret < 0)) {
			pr_debug("%s returns %d\n", __func__, ret);
			return ret;
		}

		len -= ret;
		data += ret;
	}
	return _len - len;
}

/**
 * Validate contents of the buffer from userspace related to OS descriptors.
 */
static int __ffs_data_do_os_desc(enum ffs_os_desc_type type,
				 struct usb_os_desc_header *h, void *data,
				 unsigned len, void *priv)
{
	struct ffs_data *ffs = priv;
	u8 length;

	ENTER();

	switch (type) {
	case FFS_OS_DESC_EXT_COMPAT: {
		struct usb_ext_compat_desc *d = data;
		int i;

		if (len < sizeof(*d) ||
		    d->bFirstInterfaceNumber >= ffs->interfaces_count)
			return -EINVAL;
		if (d->Reserved1 != 1) {
			/*
			 * According to the spec, Reserved1 must be set to 1
			 * but older kernels incorrectly rejected non-zero
			 * values.  We fix it here to avoid returning EINVAL
			 * in response to values we used to accept.
			 */
			pr_debug("usb_ext_compat_desc::Reserved1 forced to 1\n");
			d->Reserved1 = 1;
		}
		for (i = 0; i < ARRAY_SIZE(d->Reserved2); ++i)
			if (d->Reserved2[i])
				return -EINVAL;

		length = sizeof(struct usb_ext_compat_desc);
	}
		break;
	case FFS_OS_DESC_EXT_PROP: {
		struct usb_ext_prop_desc *d = data;
		u32 type, pdl;
		u16 pnl;

		if (len < sizeof(*d) || h->interface >= ffs->interfaces_count)
			return -EINVAL;
		length = le32_to_cpu(d->dwSize);
		if (len < length)
			return -EINVAL;
		type = le32_to_cpu(d->dwPropertyDataType);
		if (type < USB_EXT_PROP_UNICODE ||
		    type > USB_EXT_PROP_UNICODE_MULTI) {
			pr_vdebug("unsupported os descriptor property type: %d",
				  type);
			return -EINVAL;
		}
		pnl = le16_to_cpu(d->wPropertyNameLength);
		if (length < 14 + pnl) {
			pr_vdebug("invalid os descriptor length: %d pnl:%d (descriptor %d)\n",
				  length, pnl, type);
			return -EINVAL;
		}
		pdl = le32_to_cpu(*(__le32 *)((u8 *)data + 10 + pnl));
		if (length != 14 + pnl + pdl) {
			pr_vdebug("invalid os descriptor length: %d pnl:%d pdl:%d (descriptor %d)\n",
				  length, pnl, pdl, type);
			return -EINVAL;
		}
		++ffs->ms_os_descs_ext_prop_count;
		/* property name reported to the host as "WCHAR"s */
		ffs->ms_os_descs_ext_prop_name_len += pnl * 2;
		ffs->ms_os_descs_ext_prop_data_len += pdl;
	}
		break;
	default:
		pr_vdebug("unknown descriptor: %d\n", type);
		return -EINVAL;
	}
	return length;
}

static int __ffs_data_got_descs(struct ffs_data *ffs,
				char *const _data, size_t len)
{
	char *data = _data, *raw_descs;
	unsigned os_descs_count = 0, counts[3], flags;
	int ret = -EINVAL, i;
	struct ffs_desc_helper helper;

	ENTER();

	if (get_unaligned_le32(data + 4) != len)
		goto error;

	switch (get_unaligned_le32(data)) {
	case FUNCTIONFS_DESCRIPTORS_MAGIC:
		flags = FUNCTIONFS_HAS_FS_DESC | FUNCTIONFS_HAS_HS_DESC;
		data += 8;
		len  -= 8;
		break;
	case FUNCTIONFS_DESCRIPTORS_MAGIC_V2:
		flags = get_unaligned_le32(data + 8);
		ffs->user_flags = flags;
		if (flags & ~(FUNCTIONFS_HAS_FS_DESC |
			      FUNCTIONFS_HAS_HS_DESC |
			      FUNCTIONFS_HAS_SS_DESC |
			      FUNCTIONFS_HAS_MS_OS_DESC |
			      FUNCTIONFS_VIRTUAL_ADDR |
			      FUNCTIONFS_EVENTFD |
			      FUNCTIONFS_ALL_CTRL_RECIP |
			      FUNCTIONFS_CONFIG0_SETUP)) {
			ret = -ENOSYS;
			goto error;
		}
		data += 12;
		len  -= 12;
		break;
	default:
		goto error;
	}

	if (flags & FUNCTIONFS_EVENTFD) {
		if (len < 4)
			goto error;
		ffs->ffs_eventfd =
			eventfd_ctx_fdget((int)get_unaligned_le32(data));
		if (IS_ERR(ffs->ffs_eventfd)) {
			ret = PTR_ERR(ffs->ffs_eventfd);
			ffs->ffs_eventfd = NULL;
			goto error;
		}
		data += 4;
		len  -= 4;
	}

	/* Read fs_count, hs_count and ss_count (if present) */
	for (i = 0; i < 3; ++i) {
		if (!(flags & (1 << i))) {
			counts[i] = 0;
		} else if (len < 4) {
			goto error;
		} else {
			counts[i] = get_unaligned_le32(data);
			data += 4;
			len  -= 4;
		}
	}
	if (flags & (1 << i)) {
		if (len < 4) {
			goto error;
		}
		os_descs_count = get_unaligned_le32(data);
		data += 4;
		len -= 4;
	};

	/* Read descriptors */
	raw_descs = data;
	helper.ffs = ffs;
	for (i = 0; i < 3; ++i) {
		if (!counts[i])
			continue;
		helper.interfaces_count = 0;
		helper.eps_count = 0;
		ret = ffs_do_descs(counts[i], data, len,
				   __ffs_data_do_entity, &helper);
		if (ret < 0)
			goto error;
		if (!ffs->eps_count && !ffs->interfaces_count) {
			ffs->eps_count = helper.eps_count;
			ffs->interfaces_count = helper.interfaces_count;
		} else {
			if (ffs->eps_count != helper.eps_count) {
				ret = -EINVAL;
				goto error;
			}
			if (ffs->interfaces_count != helper.interfaces_count) {
				ret = -EINVAL;
				goto error;
			}
		}
		data += ret;
		len  -= ret;
	}
	if (os_descs_count) {
		ret = ffs_do_os_descs(os_descs_count, data, len,
				      __ffs_data_do_os_desc, ffs);
		if (ret < 0)
			goto error;
		data += ret;
		len -= ret;
	}

	if (raw_descs == data || len) {
		ret = -EINVAL;
		goto error;
	}

	ffs->raw_descs_data	= _data;
	ffs->raw_descs		= raw_descs;
	ffs->raw_descs_length	= data - raw_descs;
	ffs->fs_descs_count	= counts[0];
	ffs->hs_descs_count	= counts[1];
	ffs->ss_descs_count	= counts[2];
	ffs->ms_os_descs_count	= os_descs_count;

	return 0;

error:
	kfree(_data);
	return ret;
}

static int __ffs_data_got_strings(struct ffs_data *ffs,
				  char *const _data, size_t len)
{
	u32 str_count, needed_count, lang_count;
	struct usb_gadget_strings **stringtabs, *t;
	const char *data = _data;
	struct usb_string *s;

	ENTER();

	if (unlikely(len < 16 ||
		     get_unaligned_le32(data) != FUNCTIONFS_STRINGS_MAGIC ||
		     get_unaligned_le32(data + 4) != len))
		goto error;
	str_count  = get_unaligned_le32(data + 8);
	lang_count = get_unaligned_le32(data + 12);

	/* if one is zero the other must be zero */
	if (unlikely(!str_count != !lang_count))
		goto error;

	/* Do we have at least as many strings as descriptors need? */
	needed_count = ffs->strings_count;
	if (unlikely(str_count < needed_count))
		goto error;

	/*
	 * If we don't need any strings just return and free all
	 * memory.
	 */
	if (!needed_count) {
		kfree(_data);
		return 0;
	}

	/* Allocate everything in one chunk so there's less maintenance. */
	{
		unsigned i = 0;
		vla_group(d);
		vla_item(d, struct usb_gadget_strings *, stringtabs,
			lang_count + 1);
		vla_item(d, struct usb_gadget_strings, stringtab, lang_count);
		vla_item(d, struct usb_string, strings,
			lang_count*(needed_count+1));

		char *vlabuf = kmalloc(vla_group_size(d), GFP_KERNEL);

		if (unlikely(!vlabuf)) {
			kfree(_data);
			return -ENOMEM;
		}

		/* Initialize the VLA pointers */
		stringtabs = vla_ptr(vlabuf, d, stringtabs);
		t = vla_ptr(vlabuf, d, stringtab);
		i = lang_count;
		do {
			*stringtabs++ = t++;
		} while (--i);
		*stringtabs = NULL;

		/* stringtabs = vlabuf = d_stringtabs for later kfree */
		stringtabs = vla_ptr(vlabuf, d, stringtabs);
		t = vla_ptr(vlabuf, d, stringtab);
		s = vla_ptr(vlabuf, d, strings);
	}

	/* For each language */
	data += 16;
	len -= 16;

	do { /* lang_count > 0 so we can use do-while */
		unsigned needed = needed_count;

		if (unlikely(len < 3))
			goto error_free;
		t->language = get_unaligned_le16(data);
		t->strings  = s;
		++t;

		data += 2;
		len -= 2;

		/* For each string */
		do { /* str_count > 0 so we can use do-while */
			size_t length = strnlen(data, len);

			if (unlikely(length == len))
				goto error_free;

			/*
			 * User may provide more strings then we need,
			 * if that's the case we simply ignore the
			 * rest
			 */
			if (likely(needed)) {
				/*
				 * s->id will be set while adding
				 * function to configuration so for
				 * now just leave garbage here.
				 */
				s->s = data;
				--needed;
				++s;
			}

			data += length + 1;
			len -= length + 1;
		} while (--str_count);

		s->id = 0;   /* terminator */
		s->s = NULL;
		++s;

	} while (--lang_count);

	/* Some garbage left? */
	if (unlikely(len))
		goto error_free;

	/* Done! */
	ffs->stringtabs = stringtabs;
	ffs->raw_strings = _data;

	return 0;

error_free:
	kfree(stringtabs);
error:
	kfree(_data);
	return -EINVAL;
}


/* Events handling and management *******************************************/

static void __ffs_event_add(struct ffs_data *ffs,
			    enum usb_functionfs_event_type type)
{
	enum usb_functionfs_event_type rem_type1, rem_type2 = type;
	int neg = 0;

	/*
	 * Abort any unhandled setup
	 *
	 * We do not need to worry about some cmpxchg() changing value
	 * of ffs->setup_state without holding the lock because when
	 * state is FFS_SETUP_PENDING cmpxchg() in several places in
	 * the source does nothing.
	 */
	if (ffs->setup_state == FFS_SETUP_PENDING)
		ffs->setup_state = FFS_SETUP_CANCELLED;

	/*
	 * Logic of this function guarantees that there are at most four pending
	 * evens on ffs->ev.types queue.  This is important because the queue
	 * has space for four elements only and __ffs_ep0_read_events function
	 * depends on that limit as well.  If more event types are added, those
	 * limits have to be revisited or guaranteed to still hold.
	 */
	switch (type) {
	case FUNCTIONFS_RESUME:
		rem_type2 = FUNCTIONFS_SUSPEND;
		/* FALL THROUGH */
	case FUNCTIONFS_SUSPEND:
	case FUNCTIONFS_SETUP:
		rem_type1 = type;
		/* Discard all similar events */
		break;

	case FUNCTIONFS_BIND:
	case FUNCTIONFS_UNBIND:
	case FUNCTIONFS_DISABLE:
	case FUNCTIONFS_ENABLE:
		/* Discard everything other then power management. */
		rem_type1 = FUNCTIONFS_SUSPEND;
		rem_type2 = FUNCTIONFS_RESUME;
		neg = 1;
		break;

	default:
		WARN(1, "%d: unknown event, this should not happen\n", type);
		return;
	}

	{
		u8 *ev  = ffs->ev.types, *out = ev;
		unsigned n = ffs->ev.count;
		for (; n; --n, ++ev)
			if ((*ev == rem_type1 || *ev == rem_type2) == neg)
				*out++ = *ev;
			else
				pr_vdebug("purging event %d\n", *ev);
		ffs->ev.count = out - ffs->ev.types;
	}

	pr_vdebug("adding event %d\n", type);
	ffs->ev.types[ffs->ev.count++] = type;
	wake_up_locked(&ffs->ev.waitq);
	if (ffs->ffs_eventfd)
		eventfd_signal(ffs->ffs_eventfd, 1);
}

static void ffs_event_add(struct ffs_data *ffs,
			  enum usb_functionfs_event_type type)
{
	unsigned long flags;
	spin_lock_irqsave(&ffs->ev.waitq.lock, flags);
	__ffs_event_add(ffs, type);
	spin_unlock_irqrestore(&ffs->ev.waitq.lock, flags);
}

/* Bind/unbind USB function hooks *******************************************/

static int ffs_ep_addr2idx(struct ffs_data *ffs, u8 endpoint_address)
{
	int i;

	for (i = 1; i < ARRAY_SIZE(ffs->eps_addrmap); ++i)
		if (ffs->eps_addrmap[i] == endpoint_address)
			return i;
	return -ENOENT;
}

static int __ffs_func_bind_do_descs(enum ffs_entity_type type, u8 *valuep,
				    struct usb_descriptor_header *desc,
				    void *priv)
{
	struct usb_endpoint_descriptor *ds = (void *)desc;
	struct ffs_function *func = priv;
	struct ffs_ep *ffs_ep;
	unsigned ep_desc_id;
	int idx;
	static const char *speed_names[] = { "full", "high", "super" };

	if (type != FFS_DESCRIPTOR)
		return 0;

	/*
	 * If ss_descriptors is not NULL, we are reading super speed
	 * descriptors; if hs_descriptors is not NULL, we are reading high
	 * speed descriptors; otherwise, we are reading full speed
	 * descriptors.
	 */
	if (func->function.ss_descriptors) {
		ep_desc_id = 2;
		func->function.ss_descriptors[(long)valuep] = desc;
	} else if (func->function.hs_descriptors) {
		ep_desc_id = 1;
		func->function.hs_descriptors[(long)valuep] = desc;
	} else {
		ep_desc_id = 0;
		func->function.fs_descriptors[(long)valuep]    = desc;
	}

	if (!desc || desc->bDescriptorType != USB_DT_ENDPOINT)
		return 0;

	idx = ffs_ep_addr2idx(func->ffs, ds->bEndpointAddress) - 1;
	if (idx < 0)
		return idx;

	ffs_ep = func->eps + idx;

	if (unlikely(ffs_ep->descs[ep_desc_id])) {
		pr_err("two %sspeed descriptors for EP %d\n",
			  speed_names[ep_desc_id],
			  ds->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
		return -EINVAL;
	}
	ffs_ep->descs[ep_desc_id] = ds;

	ffs_dump_mem(": Original  ep desc", ds, ds->bLength);
	if (ffs_ep->ep) {
		ds->bEndpointAddress = ffs_ep->descs[0]->bEndpointAddress;
		if (!ds->wMaxPacketSize)
			ds->wMaxPacketSize = ffs_ep->descs[0]->wMaxPacketSize;
	} else {
		struct usb_request *req;
		struct usb_ep *ep;
		u8 bEndpointAddress;

		/*
		 * We back up bEndpointAddress because autoconfig overwrites
		 * it with physical endpoint address.
		 */
		bEndpointAddress = ds->bEndpointAddress;
		pr_vdebug("autoconfig\n");
		ep = usb_ep_autoconfig(func->gadget, ds);
		if (unlikely(!ep))
			return -ENOTSUPP;
		ep->driver_data = func->eps + idx;

		req = usb_ep_alloc_request(ep, GFP_KERNEL);
		if (unlikely(!req))
			return -ENOMEM;

		ffs_ep->ep  = ep;
		ffs_ep->req = req;
		func->eps_revmap[ds->bEndpointAddress &
				 USB_ENDPOINT_NUMBER_MASK] = idx + 1;
		/*
		 * If we use virtual address mapping, we restore
		 * original bEndpointAddress value.
		 */
		if (func->ffs->user_flags & FUNCTIONFS_VIRTUAL_ADDR)
			ds->bEndpointAddress = bEndpointAddress;
	}
	ffs_dump_mem(": Rewritten ep desc", ds, ds->bLength);

	return 0;
}

static int __ffs_func_bind_do_nums(enum ffs_entity_type type, u8 *valuep,
				   struct usb_descriptor_header *desc,
				   void *priv)
{
	struct ffs_function *func = priv;
	unsigned idx;
	u8 newValue;

	switch (type) {
	default:
	case FFS_DESCRIPTOR:
		/* Handled in previous pass by __ffs_func_bind_do_descs() */
		return 0;

	case FFS_INTERFACE:
		idx = *valuep;
		if (func->interfaces_nums[idx] < 0) {
			int id = usb_interface_id(func->conf, &func->function);
			if (unlikely(id < 0))
				return id;
			func->interfaces_nums[idx] = id;
		}
		newValue = func->interfaces_nums[idx];
		break;

	case FFS_STRING:
		/* String' IDs are allocated when fsf_data is bound to cdev */
		newValue = func->ffs->stringtabs[0]->strings[*valuep - 1].id;
		break;

	case FFS_ENDPOINT:
		/*
		 * USB_DT_ENDPOINT are handled in
		 * __ffs_func_bind_do_descs().
		 */
		if (desc->bDescriptorType == USB_DT_ENDPOINT)
			return 0;

		idx = (*valuep & USB_ENDPOINT_NUMBER_MASK) - 1;
		if (unlikely(!func->eps[idx].ep))
			return -EINVAL;

		{
			struct usb_endpoint_descriptor **descs;
			descs = func->eps[idx].descs;
			newValue = descs[descs[0] ? 0 : 1]->bEndpointAddress;
		}
		break;
	}

	pr_vdebug("%02x -> %02x\n", *valuep, newValue);
	*valuep = newValue;
	return 0;
}

static int __ffs_func_bind_do_os_desc(enum ffs_os_desc_type type,
				      struct usb_os_desc_header *h, void *data,
				      unsigned len, void *priv)
{
	struct ffs_function *func = priv;
	u8 length = 0;

	switch (type) {
	case FFS_OS_DESC_EXT_COMPAT: {
		struct usb_ext_compat_desc *desc = data;
		struct usb_os_desc_table *t;

		t = &func->function.os_desc_table[desc->bFirstInterfaceNumber];
		t->if_id = func->interfaces_nums[desc->bFirstInterfaceNumber];
		memcpy(t->os_desc->ext_compat_id, &desc->CompatibleID,
		       ARRAY_SIZE(desc->CompatibleID) +
		       ARRAY_SIZE(desc->SubCompatibleID));
		length = sizeof(*desc);
	}
		break;
	case FFS_OS_DESC_EXT_PROP: {
		struct usb_ext_prop_desc *desc = data;
		struct usb_os_desc_table *t;
		struct usb_os_desc_ext_prop *ext_prop;
		char *ext_prop_name;
		char *ext_prop_data;

		t = &func->function.os_desc_table[h->interface];
		t->if_id = func->interfaces_nums[h->interface];

		ext_prop = func->ffs->ms_os_descs_ext_prop_avail;
		func->ffs->ms_os_descs_ext_prop_avail += sizeof(*ext_prop);

		ext_prop->type = le32_to_cpu(desc->dwPropertyDataType);
		ext_prop->name_len = le16_to_cpu(desc->wPropertyNameLength);
		ext_prop->data_len = le32_to_cpu(*(__le32 *)
			usb_ext_prop_data_len_ptr(data, ext_prop->name_len));
		length = ext_prop->name_len + ext_prop->data_len + 14;

		ext_prop_name = func->ffs->ms_os_descs_ext_prop_name_avail;
		func->ffs->ms_os_descs_ext_prop_name_avail +=
			ext_prop->name_len;

		ext_prop_data = func->ffs->ms_os_descs_ext_prop_data_avail;
		func->ffs->ms_os_descs_ext_prop_data_avail +=
			ext_prop->data_len;
		memcpy(ext_prop_data,
		       usb_ext_prop_data_ptr(data, ext_prop->name_len),
		       ext_prop->data_len);
		/* unicode data reported to the host as "WCHAR"s */
		switch (ext_prop->type) {
		case USB_EXT_PROP_UNICODE:
		case USB_EXT_PROP_UNICODE_ENV:
		case USB_EXT_PROP_UNICODE_LINK:
		case USB_EXT_PROP_UNICODE_MULTI:
			ext_prop->data_len *= 2;
			break;
		}
		ext_prop->data = ext_prop_data;

		memcpy(ext_prop_name, usb_ext_prop_name_ptr(data),
		       ext_prop->name_len);
		/* property name reported to the host as "WCHAR"s */
		ext_prop->name_len *= 2;
		ext_prop->name = ext_prop_name;

		t->os_desc->ext_prop_len +=
			ext_prop->name_len + ext_prop->data_len + 14;
		++t->os_desc->ext_prop_count;
		list_add_tail(&ext_prop->entry, &t->os_desc->ext_prop);
	}
		break;
	default:
		pr_vdebug("unknown descriptor: %d\n", type);
	}

	return length;
}

static inline struct f_fs_opts *ffs_do_functionfs_bind(struct usb_function *f,
						struct usb_configuration *c)
{
	struct ffs_function *func = ffs_func_from_usb(f);
	struct f_fs_opts *ffs_opts =
		container_of(f->fi, struct f_fs_opts, func_inst);
	int ret;

	ENTER();

	/*
	 * Legacy gadget triggers binding in functionfs_ready_callback,
	 * which already uses locking; taking the same lock here would
	 * cause a deadlock.
	 *
	 * Configfs-enabled gadgets however do need ffs_dev_lock.
	 */
	if (!ffs_opts->no_configfs)
		ffs_dev_lock();
	ret = ffs_opts->dev->desc_ready ? 0 : -ENODEV;
	func->ffs = ffs_opts->dev->ffs_data;
	if (!ffs_opts->no_configfs)
		ffs_dev_unlock();
	if (ret)
		return ERR_PTR(ret);

	func->conf = c;
	func->gadget = c->cdev->gadget;

	/*
	 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
	 * configurations are bound in sequence with list_for_each_entry,
	 * in each configuration its functions are bound in sequence
	 * with list_for_each_entry, so we assume no race condition
	 * with regard to ffs_opts->bound access
	 */
	if (!ffs_opts->refcnt) {
		ret = functionfs_bind(func->ffs, c->cdev);
		if (ret)
			return ERR_PTR(ret);
	}
	ffs_opts->refcnt++;
	func->function.strings = func->ffs->stringtabs;

	return ffs_opts;
}

static int _ffs_func_bind(struct usb_configuration *c,
			  struct usb_function *f)
{
	struct ffs_function *func = ffs_func_from_usb(f);
	struct ffs_data *ffs = func->ffs;

	const int full = !!func->ffs->fs_descs_count;
	const int high = !!func->ffs->hs_descs_count;
	const int super = !!func->ffs->ss_descs_count;

	int fs_len, hs_len, ss_len, ret, i;
	struct ffs_ep *eps_ptr;

	/* Make it a single chunk, less management later on */
	vla_group(d);
	vla_item_with_sz(d, struct ffs_ep, eps, ffs->eps_count);
	vla_item_with_sz(d, struct usb_descriptor_header *, fs_descs,
		full ? ffs->fs_descs_count + 1 : 0);
	vla_item_with_sz(d, struct usb_descriptor_header *, hs_descs,
		high ? ffs->hs_descs_count + 1 : 0);
	vla_item_with_sz(d, struct usb_descriptor_header *, ss_descs,
		super ? ffs->ss_descs_count + 1 : 0);
	vla_item_with_sz(d, short, inums, ffs->interfaces_count);
	vla_item_with_sz(d, struct usb_os_desc_table, os_desc_table,
			 c->cdev->use_os_string ? ffs->interfaces_count : 0);
	vla_item_with_sz(d, char[16], ext_compat,
			 c->cdev->use_os_string ? ffs->interfaces_count : 0);
	vla_item_with_sz(d, struct usb_os_desc, os_desc,
			 c->cdev->use_os_string ? ffs->interfaces_count : 0);
	vla_item_with_sz(d, struct usb_os_desc_ext_prop, ext_prop,
			 ffs->ms_os_descs_ext_prop_count);
	vla_item_with_sz(d, char, ext_prop_name,
			 ffs->ms_os_descs_ext_prop_name_len);
	vla_item_with_sz(d, char, ext_prop_data,
			 ffs->ms_os_descs_ext_prop_data_len);
	vla_item_with_sz(d, char, raw_descs, ffs->raw_descs_length);
	char *vlabuf;

	ENTER();

	/* Has descriptors only for speeds gadget does not support */
	if (unlikely(!(full | high | super)))
		return -ENOTSUPP;

	/* Allocate a single chunk, less management later on */
	vlabuf = kzalloc(vla_group_size(d), GFP_KERNEL);
	if (unlikely(!vlabuf))
		return -ENOMEM;

	ffs->ms_os_descs_ext_prop_avail = vla_ptr(vlabuf, d, ext_prop);
	ffs->ms_os_descs_ext_prop_name_avail =
		vla_ptr(vlabuf, d, ext_prop_name);
	ffs->ms_os_descs_ext_prop_data_avail =
		vla_ptr(vlabuf, d, ext_prop_data);

	/* Copy descriptors  */
	memcpy(vla_ptr(vlabuf, d, raw_descs), ffs->raw_descs,
	       ffs->raw_descs_length);

	memset(vla_ptr(vlabuf, d, inums), 0xff, d_inums__sz);
	eps_ptr = vla_ptr(vlabuf, d, eps);
	for (i = 0; i < ffs->eps_count; i++)
		eps_ptr[i].num = -1;

	/* Save pointers
	 * d_eps == vlabuf, func->eps used to kfree vlabuf later
	*/
	func->eps             = vla_ptr(vlabuf, d, eps);
	func->interfaces_nums = vla_ptr(vlabuf, d, inums);

	/*
	 * Go through all the endpoint descriptors and allocate
	 * endpoints first, so that later we can rewrite the endpoint
	 * numbers without worrying that it may be described later on.
	 */
	if (likely(full)) {
		func->function.fs_descriptors = vla_ptr(vlabuf, d, fs_descs);
		fs_len = ffs_do_descs(ffs->fs_descs_count,
				      vla_ptr(vlabuf, d, raw_descs),
				      d_raw_descs__sz,
				      __ffs_func_bind_do_descs, func);
		if (unlikely(fs_len < 0)) {
			ret = fs_len;
			goto error;
		}
	} else {
		fs_len = 0;
	}

	if (likely(high)) {
		func->function.hs_descriptors = vla_ptr(vlabuf, d, hs_descs);
		hs_len = ffs_do_descs(ffs->hs_descs_count,
				      vla_ptr(vlabuf, d, raw_descs) + fs_len,
				      d_raw_descs__sz - fs_len,
				      __ffs_func_bind_do_descs, func);
		if (unlikely(hs_len < 0)) {
			ret = hs_len;
			goto error;
		}
	} else {
		hs_len = 0;
	}

	if (likely(super)) {
		func->function.ss_descriptors = vla_ptr(vlabuf, d, ss_descs);
		ss_len = ffs_do_descs(ffs->ss_descs_count,
				vla_ptr(vlabuf, d, raw_descs) + fs_len + hs_len,
				d_raw_descs__sz - fs_len - hs_len,
				__ffs_func_bind_do_descs, func);
		if (unlikely(ss_len < 0)) {
			ret = ss_len;
			goto error;
		}
	} else {
		ss_len = 0;
	}

	/*
	 * Now handle interface numbers allocation and interface and
	 * endpoint numbers rewriting.  We can do that in one go
	 * now.
	 */
	ret = ffs_do_descs(ffs->fs_descs_count +
			   (high ? ffs->hs_descs_count : 0) +
			   (super ? ffs->ss_descs_count : 0),
			   vla_ptr(vlabuf, d, raw_descs), d_raw_descs__sz,
			   __ffs_func_bind_do_nums, func);
	if (unlikely(ret < 0))
		goto error;

	func->function.os_desc_table = vla_ptr(vlabuf, d, os_desc_table);
	if (c->cdev->use_os_string) {
		for (i = 0; i < ffs->interfaces_count; ++i) {
			struct usb_os_desc *desc;

			desc = func->function.os_desc_table[i].os_desc =
				vla_ptr(vlabuf, d, os_desc) +
				i * sizeof(struct usb_os_desc);
			desc->ext_compat_id =
				vla_ptr(vlabuf, d, ext_compat) + i * 16;
			INIT_LIST_HEAD(&desc->ext_prop);
		}
		ret = ffs_do_os_descs(ffs->ms_os_descs_count,
				      vla_ptr(vlabuf, d, raw_descs) +
				      fs_len + hs_len + ss_len,
				      d_raw_descs__sz - fs_len - hs_len -
				      ss_len,
				      __ffs_func_bind_do_os_desc, func);
		if (unlikely(ret < 0))
			goto error;
	}
	func->function.os_desc_n =
		c->cdev->use_os_string ? ffs->interfaces_count : 0;

	/* And we're done */
	ffs_event_add(ffs, FUNCTIONFS_BIND);
	return 0;

error:
	/* XXX Do we need to release all claimed endpoints here? */
	return ret;
}

static int ffs_func_bind(struct usb_configuration *c,
			 struct usb_function *f)
{
	struct f_fs_opts *ffs_opts = ffs_do_functionfs_bind(f, c);
	struct ffs_function *func = ffs_func_from_usb(f);
	int ret;

	if (IS_ERR(ffs_opts))
		return PTR_ERR(ffs_opts);

	ret = _ffs_func_bind(c, f);
	if (ret && !--ffs_opts->refcnt)
		functionfs_unbind(func->ffs);

	return ret;
}


/* Other USB function hooks *************************************************/

static void ffs_reset_work(struct work_struct *work)
{
	struct ffs_data *ffs = container_of(work,
		struct ffs_data, reset_work);
	ffs_data_reset(ffs);
}

static int ffs_func_set_alt(struct usb_function *f,
			    unsigned interface, unsigned alt)
{
	struct ffs_function *func = ffs_func_from_usb(f);
	struct ffs_data *ffs = func->ffs;
	int ret = 0, intf;

	if (alt != (unsigned)-1) {
		intf = ffs_func_revmap_intf(func, interface);
		if (unlikely(intf < 0))
			return intf;
	}

	if (ffs->func)
		ffs_func_eps_disable(ffs->func);

	if (ffs->state == FFS_DEACTIVATED) {
		ffs->state = FFS_CLOSING;
		INIT_WORK(&ffs->reset_work, ffs_reset_work);
		schedule_work(&ffs->reset_work);
		return -ENODEV;
	}

	if (ffs->state != FFS_ACTIVE)
		return -ENODEV;

	if (alt == (unsigned)-1) {
		ffs->func = NULL;
		ffs_event_add(ffs, FUNCTIONFS_DISABLE);
		return 0;
	}

	ffs->func = func;
	ret = ffs_func_eps_enable(func);
	if (likely(ret >= 0))
		ffs_event_add(ffs, FUNCTIONFS_ENABLE);
	return ret;
}

static void ffs_func_disable(struct usb_function *f)
{
	ffs_func_set_alt(f, 0, (unsigned)-1);
}

static int ffs_func_setup(struct usb_function *f,
			  const struct usb_ctrlrequest *creq)
{
	struct ffs_function *func = ffs_func_from_usb(f);
	struct ffs_data *ffs = func->ffs;
	unsigned long flags;
	int ret;

	ENTER();

	pr_vdebug("creq->bRequestType = %02x\n", creq->bRequestType);
	pr_vdebug("creq->bRequest     = %02x\n", creq->bRequest);
	pr_vdebug("creq->wValue       = %04x\n", le16_to_cpu(creq->wValue));
	pr_vdebug("creq->wIndex       = %04x\n", le16_to_cpu(creq->wIndex));
	pr_vdebug("creq->wLength      = %04x\n", le16_to_cpu(creq->wLength));

	/*
	 * Most requests directed to interface go through here
	 * (notable exceptions are set/get interface) so we need to
	 * handle them.  All other either handled by composite or
	 * passed to usb_configuration->setup() (if one is set).  No
	 * matter, we will handle requests directed to endpoint here
	 * as well (as it's straightforward).  Other request recipient
	 * types are only handled when the user flag FUNCTIONFS_ALL_CTRL_RECIP
	 * is being used.
	 */
	if (ffs->state != FFS_ACTIVE)
		return -ENODEV;

	switch (creq->bRequestType & USB_RECIP_MASK) {
	case USB_RECIP_INTERFACE:
		ret = ffs_func_revmap_intf(func, le16_to_cpu(creq->wIndex));
		if (unlikely(ret < 0))
			return ret;
		break;

	case USB_RECIP_ENDPOINT:
		ret = ffs_func_revmap_ep(func, le16_to_cpu(creq->wIndex));
		if (unlikely(ret < 0))
			return ret;
		if (func->ffs->user_flags & FUNCTIONFS_VIRTUAL_ADDR)
			ret = func->ffs->eps_addrmap[ret];
		break;

	default:
		if (func->ffs->user_flags & FUNCTIONFS_ALL_CTRL_RECIP)
			ret = le16_to_cpu(creq->wIndex);
		else
			return -EOPNOTSUPP;
	}

	spin_lock_irqsave(&ffs->ev.waitq.lock, flags);
	ffs->ev.setup = *creq;
	ffs->ev.setup.wIndex = cpu_to_le16(ret);
	__ffs_event_add(ffs, FUNCTIONFS_SETUP);
	spin_unlock_irqrestore(&ffs->ev.waitq.lock, flags);

	return 0;
}

static bool ffs_func_req_match(struct usb_function *f,
			       const struct usb_ctrlrequest *creq,
			       bool config0)
{
	struct ffs_function *func = ffs_func_from_usb(f);

	if (config0 && !(func->ffs->user_flags & FUNCTIONFS_CONFIG0_SETUP))
		return false;

	switch (creq->bRequestType & USB_RECIP_MASK) {
	case USB_RECIP_INTERFACE:
		return (ffs_func_revmap_intf(func,
					     le16_to_cpu(creq->wIndex)) >= 0);
	case USB_RECIP_ENDPOINT:
		return (ffs_func_revmap_ep(func,
					   le16_to_cpu(creq->wIndex)) >= 0);
	default:
		return (bool) (func->ffs->user_flags &
			       FUNCTIONFS_ALL_CTRL_RECIP);
	}
}

static void ffs_func_suspend(struct usb_function *f)
{
	ENTER();
	ffs_event_add(ffs_func_from_usb(f)->ffs, FUNCTIONFS_SUSPEND);
}

static void ffs_func_resume(struct usb_function *f)
{
	ENTER();
	ffs_event_add(ffs_func_from_usb(f)->ffs, FUNCTIONFS_RESUME);
}


/* Endpoint and interface numbers reverse mapping ***************************/

static int ffs_func_revmap_ep(struct ffs_function *func, u8 num)
{
	num = func->eps_revmap[num & USB_ENDPOINT_NUMBER_MASK];
	return num ? num : -EDOM;
}

static int ffs_func_revmap_intf(struct ffs_function *func, u8 intf)
{
	short *nums = func->interfaces_nums;
	unsigned count = func->ffs->interfaces_count;

	for (; count; --count, ++nums) {
		if (*nums >= 0 && *nums == intf)
			return nums - func->interfaces_nums;
	}

	return -EDOM;
}


/* Devices management *******************************************************/

static LIST_HEAD(ffs_devices);

static struct ffs_dev *_ffs_do_find_dev(const char *name)
{
	struct ffs_dev *dev;

	if (!name)
		return NULL;

	list_for_each_entry(dev, &ffs_devices, entry) {
		if (strcmp(dev->name, name) == 0)
			return dev;
	}

	return NULL;
}

/*
 * ffs_lock must be taken by the caller of this function
 */
static struct ffs_dev *_ffs_get_single_dev(void)
{
	struct ffs_dev *dev;

	if (list_is_singular(&ffs_devices)) {
		dev = list_first_entry(&ffs_devices, struct ffs_dev, entry);
		if (dev->single)
			return dev;
	}

	return NULL;
}

/*
 * ffs_lock must be taken by the caller of this function
 */
static struct ffs_dev *_ffs_find_dev(const char *name)
{
	struct ffs_dev *dev;

	dev = _ffs_get_single_dev();
	if (dev)
		return dev;

	return _ffs_do_find_dev(name);
}

/* Configfs support *********************************************************/

static inline struct f_fs_opts *to_ffs_opts(struct config_item *item)
{
	return container_of(to_config_group(item), struct f_fs_opts,
			    func_inst.group);
}

static void ffs_attr_release(struct config_item *item)
{
	struct f_fs_opts *opts = to_ffs_opts(item);

	usb_put_function_instance(&opts->func_inst);
}

static struct configfs_item_operations ffs_item_ops = {
	.release	= ffs_attr_release,
};

static const struct config_item_type ffs_func_type = {
	.ct_item_ops	= &ffs_item_ops,
	.ct_owner	= THIS_MODULE,
};


/* Function registration interface ******************************************/

static void ffs_free_inst(struct usb_function_instance *f)
{
	struct f_fs_opts *opts;

	opts = to_f_fs_opts(f);
	ffs_dev_lock();
	_ffs_free_dev(opts->dev);
	ffs_dev_unlock();
	kfree(opts);
}

static int ffs_set_inst_name(struct usb_function_instance *fi, const char *name)
{
	if (strlen(name) >= FIELD_SIZEOF(struct ffs_dev, name))
		return -ENAMETOOLONG;
	return ffs_name_dev(to_f_fs_opts(fi)->dev, name);
}

static struct usb_function_instance *ffs_alloc_inst(void)
{
	struct f_fs_opts *opts;
	struct ffs_dev *dev;

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

	opts->func_inst.set_inst_name = ffs_set_inst_name;
	opts->func_inst.free_func_inst = ffs_free_inst;
	ffs_dev_lock();
	dev = _ffs_alloc_dev();
	ffs_dev_unlock();
	if (IS_ERR(dev)) {
		kfree(opts);
		return ERR_CAST(dev);
	}
	opts->dev = dev;
	dev->opts = opts;

	config_group_init_type_name(&opts->func_inst.group, "",
				    &ffs_func_type);
	return &opts->func_inst;
}

static void ffs_free(struct usb_function *f)
{
	kfree(ffs_func_from_usb(f));
}

static void ffs_func_unbind(struct usb_configuration *c,
			    struct usb_function *f)
{
	struct ffs_function *func = ffs_func_from_usb(f);
	struct ffs_data *ffs = func->ffs;
	struct f_fs_opts *opts =
		container_of(f->fi, struct f_fs_opts, func_inst);
	struct ffs_ep *ep = func->eps;
	unsigned count = ffs->eps_count;
	unsigned long flags;

	ENTER();
	if (ffs->func == func) {
		ffs_func_eps_disable(func);
		ffs->func = NULL;
	}

	if (!--opts->refcnt)
		functionfs_unbind(ffs);

	/* cleanup after autoconfig */
	spin_lock_irqsave(&func->ffs->eps_lock, flags);
	while (count--) {
		if (ep->ep && ep->req)
			usb_ep_free_request(ep->ep, ep->req);
		ep->req = NULL;
		++ep;
	}
	spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
	kfree(func->eps);
	func->eps = NULL;
	/*
	 * eps, descriptors and interfaces_nums are allocated in the
	 * same chunk so only one free is required.
	 */
	func->function.fs_descriptors = NULL;
	func->function.hs_descriptors = NULL;
	func->function.ss_descriptors = NULL;
	func->interfaces_nums = NULL;

	ffs_event_add(ffs, FUNCTIONFS_UNBIND);
}

static struct usb_function *ffs_alloc(struct usb_function_instance *fi)
{
	struct ffs_function *func;

	ENTER();

	func = kzalloc(sizeof(*func), GFP_KERNEL);
	if (unlikely(!func))
		return ERR_PTR(-ENOMEM);

	func->function.name    = "Function FS Gadget";

	func->function.bind    = ffs_func_bind;
	func->function.unbind  = ffs_func_unbind;
	func->function.set_alt = ffs_func_set_alt;
	func->function.disable = ffs_func_disable;
	func->function.setup   = ffs_func_setup;
	func->function.req_match = ffs_func_req_match;
	func->function.suspend = ffs_func_suspend;
	func->function.resume  = ffs_func_resume;
	func->function.free_func = ffs_free;

	return &func->function;
}

/*
 * ffs_lock must be taken by the caller of this function
 */
static struct ffs_dev *_ffs_alloc_dev(void)
{
	struct ffs_dev *dev;
	int ret;

	if (_ffs_get_single_dev())
			return ERR_PTR(-EBUSY);

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

	if (list_empty(&ffs_devices)) {
		ret = functionfs_init();
		if (ret) {
			kfree(dev);
			return ERR_PTR(ret);
		}
	}

	list_add(&dev->entry, &ffs_devices);

	return dev;
}

int ffs_name_dev(struct ffs_dev *dev, const char *name)
{
	struct ffs_dev *existing;
	int ret = 0;

	ffs_dev_lock();

	existing = _ffs_do_find_dev(name);
	if (!existing)
		strlcpy(dev->name, name, ARRAY_SIZE(dev->name));
	else if (existing != dev)
		ret = -EBUSY;

	ffs_dev_unlock();

	return ret;
}
EXPORT_SYMBOL_GPL(ffs_name_dev);

int ffs_single_dev(struct ffs_dev *dev)
{
	int ret;

	ret = 0;
	ffs_dev_lock();

	if (!list_is_singular(&ffs_devices))
		ret = -EBUSY;
	else
		dev->single = true;

	ffs_dev_unlock();
	return ret;
}
EXPORT_SYMBOL_GPL(ffs_single_dev);

/*
 * ffs_lock must be taken by the caller of this function
 */
static void _ffs_free_dev(struct ffs_dev *dev)
{
	list_del(&dev->entry);

	/* Clear the private_data pointer to stop incorrect dev access */
	if (dev->ffs_data)
		dev->ffs_data->private_data = NULL;

	kfree(dev);
	if (list_empty(&ffs_devices))
		functionfs_cleanup();
}

static void *ffs_acquire_dev(const char *dev_name)
{
	struct ffs_dev *ffs_dev;

	ENTER();
	ffs_dev_lock();

	ffs_dev = _ffs_find_dev(dev_name);
	if (!ffs_dev)
		ffs_dev = ERR_PTR(-ENOENT);
	else if (ffs_dev->mounted)
		ffs_dev = ERR_PTR(-EBUSY);
	else if (ffs_dev->ffs_acquire_dev_callback &&
	    ffs_dev->ffs_acquire_dev_callback(ffs_dev))
		ffs_dev = ERR_PTR(-ENOENT);
	else
		ffs_dev->mounted = true;

	ffs_dev_unlock();
	return ffs_dev;
}

static void ffs_release_dev(struct ffs_data *ffs_data)
{
	struct ffs_dev *ffs_dev;

	ENTER();
	ffs_dev_lock();

	ffs_dev = ffs_data->private_data;
	if (ffs_dev) {
		ffs_dev->mounted = false;

		if (ffs_dev->ffs_release_dev_callback)
			ffs_dev->ffs_release_dev_callback(ffs_dev);
	}

	ffs_dev_unlock();
}

static int ffs_ready(struct ffs_data *ffs)
{
	struct ffs_dev *ffs_obj;
	int ret = 0;

	ENTER();
	ffs_dev_lock();

	ffs_obj = ffs->private_data;
	if (!ffs_obj) {
		ret = -EINVAL;
		goto done;
	}
	if (WARN_ON(ffs_obj->desc_ready)) {
		ret = -EBUSY;
		goto done;
	}

	ffs_obj->desc_ready = true;
	ffs_obj->ffs_data = ffs;

	if (ffs_obj->ffs_ready_callback) {
		ret = ffs_obj->ffs_ready_callback(ffs);
		if (ret)
			goto done;
	}

	set_bit(FFS_FL_CALL_CLOSED_CALLBACK, &ffs->flags);
done:
	ffs_dev_unlock();
	return ret;
}

static void ffs_closed(struct ffs_data *ffs)
{
	struct ffs_dev *ffs_obj;
	struct f_fs_opts *opts;
	struct config_item *ci;

	ENTER();
	ffs_dev_lock();

	ffs_obj = ffs->private_data;
	if (!ffs_obj)
		goto done;

	ffs_obj->desc_ready = false;
	ffs_obj->ffs_data = NULL;

	if (test_and_clear_bit(FFS_FL_CALL_CLOSED_CALLBACK, &ffs->flags) &&
	    ffs_obj->ffs_closed_callback)
		ffs_obj->ffs_closed_callback(ffs);

	if (ffs_obj->opts)
		opts = ffs_obj->opts;
	else
		goto done;

	if (opts->no_configfs || !opts->func_inst.group.cg_item.ci_parent
	    || !kref_read(&opts->func_inst.group.cg_item.ci_kref))
		goto done;

	ci = opts->func_inst.group.cg_item.ci_parent->ci_parent;
	ffs_dev_unlock();

	if (test_bit(FFS_FL_BOUND, &ffs->flags))
		unregister_gadget_item(ci);
	return;
done:
	ffs_dev_unlock();
}

/* Misc helper functions ****************************************************/

static int ffs_mutex_lock(struct mutex *mutex, unsigned nonblock)
{
	return nonblock
		? likely(mutex_trylock(mutex)) ? 0 : -EAGAIN
		: mutex_lock_interruptible(mutex);
}

static char *ffs_prepare_buffer(const char __user *buf, size_t len)
{
	char *data;

	if (unlikely(!len))
		return NULL;

	data = kmalloc(len, GFP_KERNEL);
	if (unlikely(!data))
		return ERR_PTR(-ENOMEM);

	if (unlikely(copy_from_user(data, buf, len))) {
		kfree(data);
		return ERR_PTR(-EFAULT);
	}

	pr_vdebug("Buffer from user space:\n");
	ffs_dump_mem("", data, len);

	return data;
}

DECLARE_USB_FUNCTION_INIT(ffs, ffs_alloc_inst, ffs_alloc);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michal Nazarewicz");