summaryrefslogtreecommitdiff
path: root/drivers/comedi/comedi_fops.c
blob: b9df9b19d4bd97cdbc7a594ae928a8c4821f871f (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
// SPDX-License-Identifier: GPL-2.0+
/*
 * comedi/comedi_fops.c
 * comedi kernel module
 *
 * COMEDI - Linux Control and Measurement Device Interface
 * Copyright (C) 1997-2007 David A. Schleef <ds@schleef.org>
 * compat ioctls:
 * Author: Ian Abbott, MEV Ltd. <abbotti@mev.co.uk>
 * Copyright (C) 2007 MEV Ltd. <http://www.mev.co.uk/>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/sched/signal.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/comedi/comedidev.h>
#include <linux/cdev.h>

#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/compat.h>

#include "comedi_internal.h"

/*
 * comedi_subdevice "runflags"
 * COMEDI_SRF_RT:		DEPRECATED: command is running real-time
 * COMEDI_SRF_ERROR:		indicates an COMEDI_CB_ERROR event has occurred
 *				since the last command was started
 * COMEDI_SRF_RUNNING:		command is running
 * COMEDI_SRF_FREE_SPRIV:	free s->private on detach
 *
 * COMEDI_SRF_BUSY_MASK:	runflags that indicate the subdevice is "busy"
 */
#define COMEDI_SRF_RT		BIT(1)
#define COMEDI_SRF_ERROR	BIT(2)
#define COMEDI_SRF_RUNNING	BIT(27)
#define COMEDI_SRF_FREE_SPRIV	BIT(31)

#define COMEDI_SRF_BUSY_MASK	(COMEDI_SRF_ERROR | COMEDI_SRF_RUNNING)

/**
 * struct comedi_file - Per-file private data for COMEDI device
 * @dev: COMEDI device.
 * @read_subdev: Current "read" subdevice.
 * @write_subdev: Current "write" subdevice.
 * @last_detach_count: Last known detach count.
 * @last_attached: Last known attached/detached state.
 */
struct comedi_file {
	struct comedi_device *dev;
	struct comedi_subdevice *read_subdev;
	struct comedi_subdevice *write_subdev;
	unsigned int last_detach_count;
	unsigned int last_attached:1;
};

#define COMEDI_NUM_MINORS 0x100
#define COMEDI_NUM_SUBDEVICE_MINORS	\
	(COMEDI_NUM_MINORS - COMEDI_NUM_BOARD_MINORS)

static unsigned short comedi_num_legacy_minors;
module_param(comedi_num_legacy_minors, ushort, 0444);
MODULE_PARM_DESC(comedi_num_legacy_minors,
		 "number of comedi minor devices to reserve for non-auto-configured devices (default 0)"
		);

unsigned int comedi_default_buf_size_kb = CONFIG_COMEDI_DEFAULT_BUF_SIZE_KB;
module_param(comedi_default_buf_size_kb, uint, 0644);
MODULE_PARM_DESC(comedi_default_buf_size_kb,
		 "default asynchronous buffer size in KiB (default "
		 __MODULE_STRING(CONFIG_COMEDI_DEFAULT_BUF_SIZE_KB) ")");

unsigned int comedi_default_buf_maxsize_kb =
	CONFIG_COMEDI_DEFAULT_BUF_MAXSIZE_KB;
module_param(comedi_default_buf_maxsize_kb, uint, 0644);
MODULE_PARM_DESC(comedi_default_buf_maxsize_kb,
		 "default maximum size of asynchronous buffer in KiB (default "
		 __MODULE_STRING(CONFIG_COMEDI_DEFAULT_BUF_MAXSIZE_KB) ")");

static DEFINE_MUTEX(comedi_board_minor_table_lock);
static struct comedi_device
*comedi_board_minor_table[COMEDI_NUM_BOARD_MINORS];

static DEFINE_MUTEX(comedi_subdevice_minor_table_lock);
/* Note: indexed by minor - COMEDI_NUM_BOARD_MINORS. */
static struct comedi_subdevice
*comedi_subdevice_minor_table[COMEDI_NUM_SUBDEVICE_MINORS];

static struct cdev comedi_cdev;

static void comedi_device_init(struct comedi_device *dev)
{
	kref_init(&dev->refcount);
	spin_lock_init(&dev->spinlock);
	mutex_init(&dev->mutex);
	init_rwsem(&dev->attach_lock);
	dev->minor = -1;
}

static void comedi_dev_kref_release(struct kref *kref)
{
	struct comedi_device *dev =
		container_of(kref, struct comedi_device, refcount);

	mutex_destroy(&dev->mutex);
	put_device(dev->class_dev);
	kfree(dev);
}

/**
 * comedi_dev_put() - Release a use of a COMEDI device
 * @dev: COMEDI device.
 *
 * Must be called when a user of a COMEDI device is finished with it.
 * When the last user of the COMEDI device calls this function, the
 * COMEDI device is destroyed.
 *
 * Return: 1 if the COMEDI device is destroyed by this call or @dev is
 * NULL, otherwise return 0.  Callers must not assume the COMEDI
 * device is still valid if this function returns 0.
 */
int comedi_dev_put(struct comedi_device *dev)
{
	if (dev)
		return kref_put(&dev->refcount, comedi_dev_kref_release);
	return 1;
}
EXPORT_SYMBOL_GPL(comedi_dev_put);

static struct comedi_device *comedi_dev_get(struct comedi_device *dev)
{
	if (dev)
		kref_get(&dev->refcount);
	return dev;
}

static void comedi_device_cleanup(struct comedi_device *dev)
{
	struct module *driver_module = NULL;

	if (!dev)
		return;
	mutex_lock(&dev->mutex);
	if (dev->attached)
		driver_module = dev->driver->module;
	comedi_device_detach(dev);
	if (driver_module && dev->use_count)
		module_put(driver_module);
	mutex_unlock(&dev->mutex);
}

static bool comedi_clear_board_dev(struct comedi_device *dev)
{
	unsigned int i = dev->minor;
	bool cleared = false;

	lockdep_assert_held(&dev->mutex);
	mutex_lock(&comedi_board_minor_table_lock);
	if (dev == comedi_board_minor_table[i]) {
		comedi_board_minor_table[i] = NULL;
		cleared = true;
	}
	mutex_unlock(&comedi_board_minor_table_lock);
	return cleared;
}

static struct comedi_device *comedi_clear_board_minor(unsigned int minor)
{
	struct comedi_device *dev;

	mutex_lock(&comedi_board_minor_table_lock);
	dev = comedi_board_minor_table[minor];
	comedi_board_minor_table[minor] = NULL;
	mutex_unlock(&comedi_board_minor_table_lock);
	return dev;
}

static struct comedi_subdevice *
comedi_subdevice_from_minor(const struct comedi_device *dev, unsigned int minor)
{
	struct comedi_subdevice *s;
	unsigned int i = minor - COMEDI_NUM_BOARD_MINORS;

	mutex_lock(&comedi_subdevice_minor_table_lock);
	s = comedi_subdevice_minor_table[i];
	if (s && s->device != dev)
		s = NULL;
	mutex_unlock(&comedi_subdevice_minor_table_lock);
	return s;
}

static struct comedi_device *comedi_dev_get_from_board_minor(unsigned int minor)
{
	struct comedi_device *dev;

	mutex_lock(&comedi_board_minor_table_lock);
	dev = comedi_dev_get(comedi_board_minor_table[minor]);
	mutex_unlock(&comedi_board_minor_table_lock);
	return dev;
}

static struct comedi_device *
comedi_dev_get_from_subdevice_minor(unsigned int minor)
{
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int i = minor - COMEDI_NUM_BOARD_MINORS;

	mutex_lock(&comedi_subdevice_minor_table_lock);
	s = comedi_subdevice_minor_table[i];
	dev = comedi_dev_get(s ? s->device : NULL);
	mutex_unlock(&comedi_subdevice_minor_table_lock);
	return dev;
}

/**
 * comedi_dev_get_from_minor() - Get COMEDI device by minor device number
 * @minor: Minor device number.
 *
 * Finds the COMEDI device associated with the minor device number, if any,
 * and increments its reference count.  The COMEDI device is prevented from
 * being freed until a matching call is made to comedi_dev_put().
 *
 * Return: A pointer to the COMEDI device if it exists, with its usage
 * reference incremented.  Return NULL if no COMEDI device exists with the
 * specified minor device number.
 */
struct comedi_device *comedi_dev_get_from_minor(unsigned int minor)
{
	if (minor < COMEDI_NUM_BOARD_MINORS)
		return comedi_dev_get_from_board_minor(minor);

	return comedi_dev_get_from_subdevice_minor(minor);
}
EXPORT_SYMBOL_GPL(comedi_dev_get_from_minor);

static struct comedi_subdevice *
comedi_read_subdevice(const struct comedi_device *dev, unsigned int minor)
{
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);
	if (minor >= COMEDI_NUM_BOARD_MINORS) {
		s = comedi_subdevice_from_minor(dev, minor);
		if (!s || (s->subdev_flags & SDF_CMD_READ))
			return s;
	}
	return dev->read_subdev;
}

static struct comedi_subdevice *
comedi_write_subdevice(const struct comedi_device *dev, unsigned int minor)
{
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);
	if (minor >= COMEDI_NUM_BOARD_MINORS) {
		s = comedi_subdevice_from_minor(dev, minor);
		if (!s || (s->subdev_flags & SDF_CMD_WRITE))
			return s;
	}
	return dev->write_subdev;
}

static void comedi_file_reset(struct file *file)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi_subdevice *s, *read_s, *write_s;
	unsigned int minor = iminor(file_inode(file));

	read_s = dev->read_subdev;
	write_s = dev->write_subdev;
	if (minor >= COMEDI_NUM_BOARD_MINORS) {
		s = comedi_subdevice_from_minor(dev, minor);
		if (!s || s->subdev_flags & SDF_CMD_READ)
			read_s = s;
		if (!s || s->subdev_flags & SDF_CMD_WRITE)
			write_s = s;
	}
	cfp->last_attached = dev->attached;
	cfp->last_detach_count = dev->detach_count;
	WRITE_ONCE(cfp->read_subdev, read_s);
	WRITE_ONCE(cfp->write_subdev, write_s);
}

static void comedi_file_check(struct file *file)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;

	if (cfp->last_attached != dev->attached ||
	    cfp->last_detach_count != dev->detach_count)
		comedi_file_reset(file);
}

static struct comedi_subdevice *comedi_file_read_subdevice(struct file *file)
{
	struct comedi_file *cfp = file->private_data;

	comedi_file_check(file);
	return READ_ONCE(cfp->read_subdev);
}

static struct comedi_subdevice *comedi_file_write_subdevice(struct file *file)
{
	struct comedi_file *cfp = file->private_data;

	comedi_file_check(file);
	return READ_ONCE(cfp->write_subdev);
}

static int resize_async_buffer(struct comedi_device *dev,
			       struct comedi_subdevice *s,
			       unsigned int new_size)
{
	struct comedi_async *async = s->async;
	int retval;

	lockdep_assert_held(&dev->mutex);

	if (new_size > async->max_bufsize)
		return -EPERM;

	if (s->busy) {
		dev_dbg(dev->class_dev,
			"subdevice is busy, cannot resize buffer\n");
		return -EBUSY;
	}
	if (comedi_buf_is_mmapped(s)) {
		dev_dbg(dev->class_dev,
			"subdevice is mmapped, cannot resize buffer\n");
		return -EBUSY;
	}

	/* make sure buffer is an integral number of pages (we round up) */
	new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;

	retval = comedi_buf_alloc(dev, s, new_size);
	if (retval < 0)
		return retval;

	if (s->buf_change) {
		retval = s->buf_change(dev, s);
		if (retval < 0)
			return retval;
	}

	dev_dbg(dev->class_dev, "subd %d buffer resized to %i bytes\n",
		s->index, async->prealloc_bufsz);
	return 0;
}

/* sysfs attribute files */

static ssize_t max_read_buffer_kb_show(struct device *csdev,
				       struct device_attribute *attr, char *buf)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size = 0;

	dev = comedi_dev_get_from_minor(minor);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->mutex);
	s = comedi_read_subdevice(dev, minor);
	if (s && (s->subdev_flags & SDF_CMD_READ) && s->async)
		size = s->async->max_bufsize / 1024;
	mutex_unlock(&dev->mutex);

	comedi_dev_put(dev);
	return sysfs_emit(buf, "%u\n", size);
}

static ssize_t max_read_buffer_kb_store(struct device *csdev,
					struct device_attribute *attr,
					const char *buf, size_t count)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size;
	int err;

	err = kstrtouint(buf, 10, &size);
	if (err)
		return err;
	if (size > (UINT_MAX / 1024))
		return -EINVAL;
	size *= 1024;

	dev = comedi_dev_get_from_minor(minor);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->mutex);
	s = comedi_read_subdevice(dev, minor);
	if (s && (s->subdev_flags & SDF_CMD_READ) && s->async)
		s->async->max_bufsize = size;
	else
		err = -EINVAL;
	mutex_unlock(&dev->mutex);

	comedi_dev_put(dev);
	return err ? err : count;
}
static DEVICE_ATTR_RW(max_read_buffer_kb);

static ssize_t read_buffer_kb_show(struct device *csdev,
				   struct device_attribute *attr, char *buf)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size = 0;

	dev = comedi_dev_get_from_minor(minor);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->mutex);
	s = comedi_read_subdevice(dev, minor);
	if (s && (s->subdev_flags & SDF_CMD_READ) && s->async)
		size = s->async->prealloc_bufsz / 1024;
	mutex_unlock(&dev->mutex);

	comedi_dev_put(dev);
	return sysfs_emit(buf, "%u\n", size);
}

static ssize_t read_buffer_kb_store(struct device *csdev,
				    struct device_attribute *attr,
				    const char *buf, size_t count)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size;
	int err;

	err = kstrtouint(buf, 10, &size);
	if (err)
		return err;
	if (size > (UINT_MAX / 1024))
		return -EINVAL;
	size *= 1024;

	dev = comedi_dev_get_from_minor(minor);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->mutex);
	s = comedi_read_subdevice(dev, minor);
	if (s && (s->subdev_flags & SDF_CMD_READ) && s->async)
		err = resize_async_buffer(dev, s, size);
	else
		err = -EINVAL;
	mutex_unlock(&dev->mutex);

	comedi_dev_put(dev);
	return err ? err : count;
}
static DEVICE_ATTR_RW(read_buffer_kb);

static ssize_t max_write_buffer_kb_show(struct device *csdev,
					struct device_attribute *attr,
					char *buf)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size = 0;

	dev = comedi_dev_get_from_minor(minor);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->mutex);
	s = comedi_write_subdevice(dev, minor);
	if (s && (s->subdev_flags & SDF_CMD_WRITE) && s->async)
		size = s->async->max_bufsize / 1024;
	mutex_unlock(&dev->mutex);

	comedi_dev_put(dev);
	return sysfs_emit(buf, "%u\n", size);
}

static ssize_t max_write_buffer_kb_store(struct device *csdev,
					 struct device_attribute *attr,
					 const char *buf, size_t count)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size;
	int err;

	err = kstrtouint(buf, 10, &size);
	if (err)
		return err;
	if (size > (UINT_MAX / 1024))
		return -EINVAL;
	size *= 1024;

	dev = comedi_dev_get_from_minor(minor);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->mutex);
	s = comedi_write_subdevice(dev, minor);
	if (s && (s->subdev_flags & SDF_CMD_WRITE) && s->async)
		s->async->max_bufsize = size;
	else
		err = -EINVAL;
	mutex_unlock(&dev->mutex);

	comedi_dev_put(dev);
	return err ? err : count;
}
static DEVICE_ATTR_RW(max_write_buffer_kb);

static ssize_t write_buffer_kb_show(struct device *csdev,
				    struct device_attribute *attr, char *buf)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size = 0;

	dev = comedi_dev_get_from_minor(minor);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->mutex);
	s = comedi_write_subdevice(dev, minor);
	if (s && (s->subdev_flags & SDF_CMD_WRITE) && s->async)
		size = s->async->prealloc_bufsz / 1024;
	mutex_unlock(&dev->mutex);

	comedi_dev_put(dev);
	return sysfs_emit(buf, "%u\n", size);
}

static ssize_t write_buffer_kb_store(struct device *csdev,
				     struct device_attribute *attr,
				     const char *buf, size_t count)
{
	unsigned int minor = MINOR(csdev->devt);
	struct comedi_device *dev;
	struct comedi_subdevice *s;
	unsigned int size;
	int err;

	err = kstrtouint(buf, 10, &size);
	if (err)
		return err;
	if (size > (UINT_MAX / 1024))
		return -EINVAL;
	size *= 1024;

	dev = comedi_dev_get_from_minor(minor);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->mutex);
	s = comedi_write_subdevice(dev, minor);
	if (s && (s->subdev_flags & SDF_CMD_WRITE) && s->async)
		err = resize_async_buffer(dev, s, size);
	else
		err = -EINVAL;
	mutex_unlock(&dev->mutex);

	comedi_dev_put(dev);
	return err ? err : count;
}
static DEVICE_ATTR_RW(write_buffer_kb);

static struct attribute *comedi_dev_attrs[] = {
	&dev_attr_max_read_buffer_kb.attr,
	&dev_attr_read_buffer_kb.attr,
	&dev_attr_max_write_buffer_kb.attr,
	&dev_attr_write_buffer_kb.attr,
	NULL,
};
ATTRIBUTE_GROUPS(comedi_dev);

static const struct class comedi_class = {
	.name = "comedi",
	.dev_groups = comedi_dev_groups,
};

static void comedi_free_board_dev(struct comedi_device *dev)
{
	if (dev) {
		comedi_device_cleanup(dev);
		if (dev->class_dev) {
			device_destroy(&comedi_class,
				       MKDEV(COMEDI_MAJOR, dev->minor));
		}
		comedi_dev_put(dev);
	}
}

static void __comedi_clear_subdevice_runflags(struct comedi_subdevice *s,
					      unsigned int bits)
{
	s->runflags &= ~bits;
}

static void __comedi_set_subdevice_runflags(struct comedi_subdevice *s,
					    unsigned int bits)
{
	s->runflags |= bits;
}

static void comedi_update_subdevice_runflags(struct comedi_subdevice *s,
					     unsigned int mask,
					     unsigned int bits)
{
	unsigned long flags;

	spin_lock_irqsave(&s->spin_lock, flags);
	__comedi_clear_subdevice_runflags(s, mask);
	__comedi_set_subdevice_runflags(s, bits & mask);
	spin_unlock_irqrestore(&s->spin_lock, flags);
}

static unsigned int __comedi_get_subdevice_runflags(struct comedi_subdevice *s)
{
	return s->runflags;
}

static unsigned int comedi_get_subdevice_runflags(struct comedi_subdevice *s)
{
	unsigned long flags;
	unsigned int runflags;

	spin_lock_irqsave(&s->spin_lock, flags);
	runflags = __comedi_get_subdevice_runflags(s);
	spin_unlock_irqrestore(&s->spin_lock, flags);
	return runflags;
}

static bool comedi_is_runflags_running(unsigned int runflags)
{
	return runflags & COMEDI_SRF_RUNNING;
}

static bool comedi_is_runflags_in_error(unsigned int runflags)
{
	return runflags & COMEDI_SRF_ERROR;
}

/**
 * comedi_is_subdevice_running() - Check if async command running on subdevice
 * @s: COMEDI subdevice.
 *
 * Return: %true if an asynchronous COMEDI command is active on the
 * subdevice, else %false.
 */
bool comedi_is_subdevice_running(struct comedi_subdevice *s)
{
	unsigned int runflags = comedi_get_subdevice_runflags(s);

	return comedi_is_runflags_running(runflags);
}
EXPORT_SYMBOL_GPL(comedi_is_subdevice_running);

static bool __comedi_is_subdevice_running(struct comedi_subdevice *s)
{
	unsigned int runflags = __comedi_get_subdevice_runflags(s);

	return comedi_is_runflags_running(runflags);
}

bool comedi_can_auto_free_spriv(struct comedi_subdevice *s)
{
	unsigned int runflags = __comedi_get_subdevice_runflags(s);

	return runflags & COMEDI_SRF_FREE_SPRIV;
}

/**
 * comedi_set_spriv_auto_free() - Mark subdevice private data as freeable
 * @s: COMEDI subdevice.
 *
 * Mark the subdevice as having a pointer to private data that can be
 * automatically freed when the COMEDI device is detached from the low-level
 * driver.
 */
void comedi_set_spriv_auto_free(struct comedi_subdevice *s)
{
	__comedi_set_subdevice_runflags(s, COMEDI_SRF_FREE_SPRIV);
}
EXPORT_SYMBOL_GPL(comedi_set_spriv_auto_free);

/**
 * comedi_alloc_spriv - Allocate memory for the subdevice private data
 * @s: COMEDI subdevice.
 * @size: Size of the memory to allocate.
 *
 * Allocate memory for the subdevice private data and point @s->private
 * to it.  The memory will be freed automatically when the COMEDI device
 * is detached from the low-level driver.
 *
 * Return: A pointer to the allocated memory @s->private on success.
 * Return NULL on failure.
 */
void *comedi_alloc_spriv(struct comedi_subdevice *s, size_t size)
{
	s->private = kzalloc(size, GFP_KERNEL);
	if (s->private)
		comedi_set_spriv_auto_free(s);
	return s->private;
}
EXPORT_SYMBOL_GPL(comedi_alloc_spriv);

/*
 * This function restores a subdevice to an idle state.
 */
static void do_become_nonbusy(struct comedi_device *dev,
			      struct comedi_subdevice *s)
{
	struct comedi_async *async = s->async;

	lockdep_assert_held(&dev->mutex);
	comedi_update_subdevice_runflags(s, COMEDI_SRF_RUNNING, 0);
	if (async) {
		comedi_buf_reset(s);
		async->inttrig = NULL;
		kfree(async->cmd.chanlist);
		async->cmd.chanlist = NULL;
		s->busy = NULL;
		wake_up_interruptible_all(&async->wait_head);
	} else {
		dev_err(dev->class_dev,
			"BUG: (?) %s called with async=NULL\n", __func__);
		s->busy = NULL;
	}
}

static int do_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
{
	int ret = 0;

	lockdep_assert_held(&dev->mutex);
	if (comedi_is_subdevice_running(s) && s->cancel)
		ret = s->cancel(dev, s);

	do_become_nonbusy(dev, s);

	return ret;
}

void comedi_device_cancel_all(struct comedi_device *dev)
{
	struct comedi_subdevice *s;
	int i;

	lockdep_assert_held(&dev->mutex);
	if (!dev->attached)
		return;

	for (i = 0; i < dev->n_subdevices; i++) {
		s = &dev->subdevices[i];
		if (s->async)
			do_cancel(dev, s);
	}
}

static int is_device_busy(struct comedi_device *dev)
{
	struct comedi_subdevice *s;
	int i;

	lockdep_assert_held(&dev->mutex);
	if (!dev->attached)
		return 0;

	for (i = 0; i < dev->n_subdevices; i++) {
		s = &dev->subdevices[i];
		if (s->busy)
			return 1;
		if (s->async && comedi_buf_is_mmapped(s))
			return 1;
	}

	return 0;
}

/*
 * COMEDI_DEVCONFIG ioctl
 * attaches (and configures) or detaches a legacy device
 *
 * arg:
 *	pointer to comedi_devconfig structure (NULL if detaching)
 *
 * reads:
 *	comedi_devconfig structure (if attaching)
 *
 * writes:
 *	nothing
 */
static int do_devconfig_ioctl(struct comedi_device *dev,
			      struct comedi_devconfig __user *arg)
{
	struct comedi_devconfig it;

	lockdep_assert_held(&dev->mutex);
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	if (!arg) {
		if (is_device_busy(dev))
			return -EBUSY;
		if (dev->attached) {
			struct module *driver_module = dev->driver->module;

			comedi_device_detach(dev);
			module_put(driver_module);
		}
		return 0;
	}

	if (copy_from_user(&it, arg, sizeof(it)))
		return -EFAULT;

	it.board_name[COMEDI_NAMELEN - 1] = 0;

	if (it.options[COMEDI_DEVCONF_AUX_DATA_LENGTH]) {
		dev_warn(dev->class_dev,
			 "comedi_config --init_data is deprecated\n");
		return -EINVAL;
	}

	if (dev->minor >= comedi_num_legacy_minors)
		/* don't re-use dynamically allocated comedi devices */
		return -EBUSY;

	/* This increments the driver module count on success. */
	return comedi_device_attach(dev, &it);
}

/*
 * COMEDI_BUFCONFIG ioctl
 * buffer configuration
 *
 * arg:
 *	pointer to comedi_bufconfig structure
 *
 * reads:
 *	comedi_bufconfig structure
 *
 * writes:
 *	modified comedi_bufconfig structure
 */
static int do_bufconfig_ioctl(struct comedi_device *dev,
			      struct comedi_bufconfig __user *arg)
{
	struct comedi_bufconfig bc;
	struct comedi_async *async;
	struct comedi_subdevice *s;
	int retval = 0;

	lockdep_assert_held(&dev->mutex);
	if (copy_from_user(&bc, arg, sizeof(bc)))
		return -EFAULT;

	if (bc.subdevice >= dev->n_subdevices)
		return -EINVAL;

	s = &dev->subdevices[bc.subdevice];
	async = s->async;

	if (!async) {
		dev_dbg(dev->class_dev,
			"subdevice does not have async capability\n");
		bc.size = 0;
		bc.maximum_size = 0;
		goto copyback;
	}

	if (bc.maximum_size) {
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;

		async->max_bufsize = bc.maximum_size;
	}

	if (bc.size) {
		retval = resize_async_buffer(dev, s, bc.size);
		if (retval < 0)
			return retval;
	}

	bc.size = async->prealloc_bufsz;
	bc.maximum_size = async->max_bufsize;

copyback:
	if (copy_to_user(arg, &bc, sizeof(bc)))
		return -EFAULT;

	return 0;
}

/*
 * COMEDI_DEVINFO ioctl
 * device info
 *
 * arg:
 *	pointer to comedi_devinfo structure
 *
 * reads:
 *	nothing
 *
 * writes:
 *	comedi_devinfo structure
 */
static int do_devinfo_ioctl(struct comedi_device *dev,
			    struct comedi_devinfo __user *arg,
			    struct file *file)
{
	struct comedi_subdevice *s;
	struct comedi_devinfo devinfo;

	lockdep_assert_held(&dev->mutex);
	memset(&devinfo, 0, sizeof(devinfo));

	/* fill devinfo structure */
	devinfo.version_code = COMEDI_VERSION_CODE;
	devinfo.n_subdevs = dev->n_subdevices;
	strscpy(devinfo.driver_name, dev->driver->driver_name, COMEDI_NAMELEN);
	strscpy(devinfo.board_name, dev->board_name, COMEDI_NAMELEN);

	s = comedi_file_read_subdevice(file);
	if (s)
		devinfo.read_subdevice = s->index;
	else
		devinfo.read_subdevice = -1;

	s = comedi_file_write_subdevice(file);
	if (s)
		devinfo.write_subdevice = s->index;
	else
		devinfo.write_subdevice = -1;

	if (copy_to_user(arg, &devinfo, sizeof(devinfo)))
		return -EFAULT;

	return 0;
}

/*
 * COMEDI_SUBDINFO ioctl
 * subdevices info
 *
 * arg:
 *	pointer to array of comedi_subdinfo structures
 *
 * reads:
 *	nothing
 *
 * writes:
 *	array of comedi_subdinfo structures
 */
static int do_subdinfo_ioctl(struct comedi_device *dev,
			     struct comedi_subdinfo __user *arg, void *file)
{
	int ret, i;
	struct comedi_subdinfo *tmp, *us;
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);
	tmp = kcalloc(dev->n_subdevices, sizeof(*tmp), GFP_KERNEL);
	if (!tmp)
		return -ENOMEM;

	/* fill subdinfo structs */
	for (i = 0; i < dev->n_subdevices; i++) {
		s = &dev->subdevices[i];
		us = tmp + i;

		us->type = s->type;
		us->n_chan = s->n_chan;
		us->subd_flags = s->subdev_flags;
		if (comedi_is_subdevice_running(s))
			us->subd_flags |= SDF_RUNNING;
#define TIMER_nanosec 5		/* backwards compatibility */
		us->timer_type = TIMER_nanosec;
		us->len_chanlist = s->len_chanlist;
		us->maxdata = s->maxdata;
		if (s->range_table) {
			us->range_type =
			    (i << 24) | (0 << 16) | (s->range_table->length);
		} else {
			us->range_type = 0;	/* XXX */
		}

		if (s->busy)
			us->subd_flags |= SDF_BUSY;
		if (s->busy == file)
			us->subd_flags |= SDF_BUSY_OWNER;
		if (s->lock)
			us->subd_flags |= SDF_LOCKED;
		if (s->lock == file)
			us->subd_flags |= SDF_LOCK_OWNER;
		if (!s->maxdata && s->maxdata_list)
			us->subd_flags |= SDF_MAXDATA;
		if (s->range_table_list)
			us->subd_flags |= SDF_RANGETYPE;
		if (s->do_cmd)
			us->subd_flags |= SDF_CMD;

		if (s->insn_bits != &insn_inval)
			us->insn_bits_support = COMEDI_SUPPORTED;
		else
			us->insn_bits_support = COMEDI_UNSUPPORTED;
	}

	ret = copy_to_user(arg, tmp, dev->n_subdevices * sizeof(*tmp));

	kfree(tmp);

	return ret ? -EFAULT : 0;
}

/*
 * COMEDI_CHANINFO ioctl
 * subdevice channel info
 *
 * arg:
 *	pointer to comedi_chaninfo structure
 *
 * reads:
 *	comedi_chaninfo structure
 *
 * writes:
 *	array of maxdata values to chaninfo->maxdata_list if requested
 *	array of range table lengths to chaninfo->range_table_list if requested
 */
static int do_chaninfo_ioctl(struct comedi_device *dev,
			     struct comedi_chaninfo *it)
{
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);

	if (it->subdev >= dev->n_subdevices)
		return -EINVAL;
	s = &dev->subdevices[it->subdev];

	if (it->maxdata_list) {
		if (s->maxdata || !s->maxdata_list)
			return -EINVAL;
		if (copy_to_user(it->maxdata_list, s->maxdata_list,
				 s->n_chan * sizeof(unsigned int)))
			return -EFAULT;
	}

	if (it->flaglist)
		return -EINVAL;	/* flaglist not supported */

	if (it->rangelist) {
		int i;

		if (!s->range_table_list)
			return -EINVAL;
		for (i = 0; i < s->n_chan; i++) {
			int x;

			x = (dev->minor << 28) | (it->subdev << 24) | (i << 16) |
			    (s->range_table_list[i]->length);
			if (put_user(x, it->rangelist + i))
				return -EFAULT;
		}
	}

	return 0;
}

/*
 * COMEDI_BUFINFO ioctl
 * buffer information
 *
 * arg:
 *	pointer to comedi_bufinfo structure
 *
 * reads:
 *	comedi_bufinfo structure
 *
 * writes:
 *	modified comedi_bufinfo structure
 */
static int do_bufinfo_ioctl(struct comedi_device *dev,
			    struct comedi_bufinfo __user *arg, void *file)
{
	struct comedi_bufinfo bi;
	struct comedi_subdevice *s;
	struct comedi_async *async;
	unsigned int runflags;
	int retval = 0;
	bool become_nonbusy = false;

	lockdep_assert_held(&dev->mutex);
	if (copy_from_user(&bi, arg, sizeof(bi)))
		return -EFAULT;

	if (bi.subdevice >= dev->n_subdevices)
		return -EINVAL;

	s = &dev->subdevices[bi.subdevice];

	async = s->async;

	if (!async || s->busy != file)
		return -EINVAL;

	runflags = comedi_get_subdevice_runflags(s);
	if (!(async->cmd.flags & CMDF_WRITE)) {
		/* command was set up in "read" direction */
		if (bi.bytes_read) {
			comedi_buf_read_alloc(s, bi.bytes_read);
			bi.bytes_read = comedi_buf_read_free(s, bi.bytes_read);
		}
		/*
		 * If nothing left to read, and command has stopped, and
		 * {"read" position not updated or command stopped normally},
		 * then become non-busy.
		 */
		if (comedi_buf_read_n_available(s) == 0 &&
		    !comedi_is_runflags_running(runflags) &&
		    (bi.bytes_read == 0 ||
		     !comedi_is_runflags_in_error(runflags))) {
			become_nonbusy = true;
			if (comedi_is_runflags_in_error(runflags))
				retval = -EPIPE;
		}
		bi.bytes_written = 0;
	} else {
		/* command was set up in "write" direction */
		if (!comedi_is_runflags_running(runflags)) {
			bi.bytes_written = 0;
			become_nonbusy = true;
			if (comedi_is_runflags_in_error(runflags))
				retval = -EPIPE;
		} else if (bi.bytes_written) {
			comedi_buf_write_alloc(s, bi.bytes_written);
			bi.bytes_written =
			    comedi_buf_write_free(s, bi.bytes_written);
		}
		bi.bytes_read = 0;
	}

	bi.buf_write_count = async->buf_write_count;
	bi.buf_write_ptr = async->buf_write_ptr;
	bi.buf_read_count = async->buf_read_count;
	bi.buf_read_ptr = async->buf_read_ptr;

	if (become_nonbusy)
		do_become_nonbusy(dev, s);

	if (retval)
		return retval;

	if (copy_to_user(arg, &bi, sizeof(bi)))
		return -EFAULT;

	return 0;
}

static int check_insn_config_length(struct comedi_insn *insn,
				    unsigned int *data)
{
	if (insn->n < 1)
		return -EINVAL;

	switch (data[0]) {
	case INSN_CONFIG_DIO_OUTPUT:
	case INSN_CONFIG_DIO_INPUT:
	case INSN_CONFIG_DISARM:
	case INSN_CONFIG_RESET:
		if (insn->n == 1)
			return 0;
		break;
	case INSN_CONFIG_ARM:
	case INSN_CONFIG_DIO_QUERY:
	case INSN_CONFIG_BLOCK_SIZE:
	case INSN_CONFIG_FILTER:
	case INSN_CONFIG_SERIAL_CLOCK:
	case INSN_CONFIG_BIDIRECTIONAL_DATA:
	case INSN_CONFIG_ALT_SOURCE:
	case INSN_CONFIG_SET_COUNTER_MODE:
	case INSN_CONFIG_8254_READ_STATUS:
	case INSN_CONFIG_SET_ROUTING:
	case INSN_CONFIG_GET_ROUTING:
	case INSN_CONFIG_GET_PWM_STATUS:
	case INSN_CONFIG_PWM_SET_PERIOD:
	case INSN_CONFIG_PWM_GET_PERIOD:
		if (insn->n == 2)
			return 0;
		break;
	case INSN_CONFIG_SET_GATE_SRC:
	case INSN_CONFIG_GET_GATE_SRC:
	case INSN_CONFIG_SET_CLOCK_SRC:
	case INSN_CONFIG_GET_CLOCK_SRC:
	case INSN_CONFIG_SET_OTHER_SRC:
	case INSN_CONFIG_GET_COUNTER_STATUS:
	case INSN_CONFIG_GET_PWM_OUTPUT:
	case INSN_CONFIG_PWM_SET_H_BRIDGE:
	case INSN_CONFIG_PWM_GET_H_BRIDGE:
	case INSN_CONFIG_GET_HARDWARE_BUFFER_SIZE:
		if (insn->n == 3)
			return 0;
		break;
	case INSN_CONFIG_PWM_OUTPUT:
	case INSN_CONFIG_ANALOG_TRIG:
	case INSN_CONFIG_TIMER_1:
		if (insn->n == 5)
			return 0;
		break;
	case INSN_CONFIG_DIGITAL_TRIG:
		if (insn->n == 6)
			return 0;
		break;
	case INSN_CONFIG_GET_CMD_TIMING_CONSTRAINTS:
		if (insn->n >= 4)
			return 0;
		break;
		/*
		 * by default we allow the insn since we don't have checks for
		 * all possible cases yet
		 */
	default:
		pr_warn("No check for data length of config insn id %i is implemented\n",
			data[0]);
		pr_warn("Add a check to %s in %s\n", __func__, __FILE__);
		pr_warn("Assuming n=%i is correct\n", insn->n);
		return 0;
	}
	return -EINVAL;
}

static int check_insn_device_config_length(struct comedi_insn *insn,
					   unsigned int *data)
{
	if (insn->n < 1)
		return -EINVAL;

	switch (data[0]) {
	case INSN_DEVICE_CONFIG_TEST_ROUTE:
	case INSN_DEVICE_CONFIG_CONNECT_ROUTE:
	case INSN_DEVICE_CONFIG_DISCONNECT_ROUTE:
		if (insn->n == 3)
			return 0;
		break;
	case INSN_DEVICE_CONFIG_GET_ROUTES:
		/*
		 * Big enough for config_id and the length of the userland
		 * memory buffer.  Additional length should be in factors of 2
		 * to communicate any returned route pairs (source,destination).
		 */
		if (insn->n >= 2)
			return 0;
		break;
	}
	return -EINVAL;
}

/**
 * get_valid_routes() - Calls low-level driver get_valid_routes function to
 *			either return a count of valid routes to user, or copy
 *			of list of all valid device routes to buffer in
 *			userspace.
 * @dev: comedi device pointer
 * @data: data from user insn call.  The length of the data must be >= 2.
 *	  data[0] must contain the INSN_DEVICE_CONFIG config_id.
 *	  data[1](input) contains the number of _pairs_ for which memory is
 *		  allotted from the user.  If the user specifies '0', then only
 *		  the number of pairs available is returned.
 *	  data[1](output) returns either the number of pairs available (if none
 *		  where requested) or the number of _pairs_ that are copied back
 *		  to the user.
 *	  data[2::2] returns each (source, destination) pair.
 *
 * Return: -EINVAL if low-level driver does not allocate and return routes as
 *	   expected.  Returns 0 otherwise.
 */
static int get_valid_routes(struct comedi_device *dev, unsigned int *data)
{
	lockdep_assert_held(&dev->mutex);
	data[1] = dev->get_valid_routes(dev, data[1], data + 2);
	return 0;
}

static int parse_insn(struct comedi_device *dev, struct comedi_insn *insn,
		      unsigned int *data, void *file)
{
	struct comedi_subdevice *s;
	int ret = 0;
	int i;

	lockdep_assert_held(&dev->mutex);
	if (insn->insn & INSN_MASK_SPECIAL) {
		/* a non-subdevice instruction */

		switch (insn->insn) {
		case INSN_GTOD:
			{
				struct timespec64 tv;

				if (insn->n != 2) {
					ret = -EINVAL;
					break;
				}

				ktime_get_real_ts64(&tv);
				/* unsigned data safe until 2106 */
				data[0] = (unsigned int)tv.tv_sec;
				data[1] = tv.tv_nsec / NSEC_PER_USEC;
				ret = 2;

				break;
			}
		case INSN_WAIT:
			if (insn->n != 1 || data[0] >= 100000) {
				ret = -EINVAL;
				break;
			}
			udelay(data[0] / 1000);
			ret = 1;
			break;
		case INSN_INTTRIG:
			if (insn->n != 1) {
				ret = -EINVAL;
				break;
			}
			if (insn->subdev >= dev->n_subdevices) {
				dev_dbg(dev->class_dev,
					"%d not usable subdevice\n",
					insn->subdev);
				ret = -EINVAL;
				break;
			}
			s = &dev->subdevices[insn->subdev];
			if (!s->async) {
				dev_dbg(dev->class_dev, "no async\n");
				ret = -EINVAL;
				break;
			}
			if (!s->async->inttrig) {
				dev_dbg(dev->class_dev, "no inttrig\n");
				ret = -EAGAIN;
				break;
			}
			ret = s->async->inttrig(dev, s, data[0]);
			if (ret >= 0)
				ret = 1;
			break;
		case INSN_DEVICE_CONFIG:
			ret = check_insn_device_config_length(insn, data);
			if (ret)
				break;

			if (data[0] == INSN_DEVICE_CONFIG_GET_ROUTES) {
				/*
				 * data[1] should be the number of _pairs_ that
				 * the memory can hold.
				 */
				data[1] = (insn->n - 2) / 2;
				ret = get_valid_routes(dev, data);
				break;
			}

			/* other global device config instructions. */
			ret = dev->insn_device_config(dev, insn, data);
			break;
		default:
			dev_dbg(dev->class_dev, "invalid insn\n");
			ret = -EINVAL;
			break;
		}
	} else {
		/* a subdevice instruction */
		unsigned int maxdata;

		if (insn->subdev >= dev->n_subdevices) {
			dev_dbg(dev->class_dev, "subdevice %d out of range\n",
				insn->subdev);
			ret = -EINVAL;
			goto out;
		}
		s = &dev->subdevices[insn->subdev];

		if (s->type == COMEDI_SUBD_UNUSED) {
			dev_dbg(dev->class_dev, "%d not usable subdevice\n",
				insn->subdev);
			ret = -EIO;
			goto out;
		}

		/* are we locked? (ioctl lock) */
		if (s->lock && s->lock != file) {
			dev_dbg(dev->class_dev, "device locked\n");
			ret = -EACCES;
			goto out;
		}

		ret = comedi_check_chanlist(s, 1, &insn->chanspec);
		if (ret < 0) {
			ret = -EINVAL;
			dev_dbg(dev->class_dev, "bad chanspec\n");
			goto out;
		}

		if (s->busy) {
			ret = -EBUSY;
			goto out;
		}
		/* This looks arbitrary.  It is. */
		s->busy = parse_insn;
		switch (insn->insn) {
		case INSN_READ:
			ret = s->insn_read(dev, s, insn, data);
			if (ret == -ETIMEDOUT) {
				dev_dbg(dev->class_dev,
					"subdevice %d read instruction timed out\n",
					s->index);
			}
			break;
		case INSN_WRITE:
			maxdata = s->maxdata_list
			    ? s->maxdata_list[CR_CHAN(insn->chanspec)]
			    : s->maxdata;
			for (i = 0; i < insn->n; ++i) {
				if (data[i] > maxdata) {
					ret = -EINVAL;
					dev_dbg(dev->class_dev,
						"bad data value(s)\n");
					break;
				}
			}
			if (ret == 0) {
				ret = s->insn_write(dev, s, insn, data);
				if (ret == -ETIMEDOUT) {
					dev_dbg(dev->class_dev,
						"subdevice %d write instruction timed out\n",
						s->index);
				}
			}
			break;
		case INSN_BITS:
			if (insn->n != 2) {
				ret = -EINVAL;
			} else {
				/*
				 * Most drivers ignore the base channel in
				 * insn->chanspec.  Fix this here if
				 * the subdevice has <= 32 channels.
				 */
				unsigned int orig_mask = data[0];
				unsigned int shift = 0;

				if (s->n_chan <= 32) {
					shift = CR_CHAN(insn->chanspec);
					if (shift > 0) {
						insn->chanspec = 0;
						data[0] <<= shift;
						data[1] <<= shift;
					}
				}
				ret = s->insn_bits(dev, s, insn, data);
				data[0] = orig_mask;
				if (shift > 0)
					data[1] >>= shift;
			}
			break;
		case INSN_CONFIG:
			ret = check_insn_config_length(insn, data);
			if (ret)
				break;
			ret = s->insn_config(dev, s, insn, data);
			break;
		default:
			ret = -EINVAL;
			break;
		}

		s->busy = NULL;
	}

out:
	return ret;
}

/*
 * COMEDI_INSNLIST ioctl
 * synchronous instruction list
 *
 * arg:
 *	pointer to comedi_insnlist structure
 *
 * reads:
 *	comedi_insnlist structure
 *	array of comedi_insn structures from insnlist->insns pointer
 *	data (for writes) from insns[].data pointers
 *
 * writes:
 *	data (for reads) to insns[].data pointers
 */
/* arbitrary limits */
#define MIN_SAMPLES 16
#define MAX_SAMPLES 65536
static int do_insnlist_ioctl(struct comedi_device *dev,
			     struct comedi_insn *insns,
			     unsigned int n_insns,
			     void *file)
{
	unsigned int *data = NULL;
	unsigned int max_n_data_required = MIN_SAMPLES;
	int i = 0;
	int ret = 0;

	lockdep_assert_held(&dev->mutex);

	/* Determine maximum memory needed for all instructions. */
	for (i = 0; i < n_insns; ++i) {
		if (insns[i].n > MAX_SAMPLES) {
			dev_dbg(dev->class_dev,
				"number of samples too large\n");
			ret = -EINVAL;
			goto error;
		}
		max_n_data_required = max(max_n_data_required, insns[i].n);
	}

	/* Allocate scratch space for all instruction data. */
	data = kmalloc_array(max_n_data_required, sizeof(unsigned int),
			     GFP_KERNEL);
	if (!data) {
		ret = -ENOMEM;
		goto error;
	}

	for (i = 0; i < n_insns; ++i) {
		if (insns[i].insn & INSN_MASK_WRITE) {
			if (copy_from_user(data, insns[i].data,
					   insns[i].n * sizeof(unsigned int))) {
				dev_dbg(dev->class_dev,
					"copy_from_user failed\n");
				ret = -EFAULT;
				goto error;
			}
		}
		ret = parse_insn(dev, insns + i, data, file);
		if (ret < 0)
			goto error;
		if (insns[i].insn & INSN_MASK_READ) {
			if (copy_to_user(insns[i].data, data,
					 insns[i].n * sizeof(unsigned int))) {
				dev_dbg(dev->class_dev,
					"copy_to_user failed\n");
				ret = -EFAULT;
				goto error;
			}
		}
		if (need_resched())
			schedule();
	}

error:
	kfree(data);

	if (ret < 0)
		return ret;
	return i;
}

/*
 * COMEDI_INSN ioctl
 * synchronous instruction
 *
 * arg:
 *	pointer to comedi_insn structure
 *
 * reads:
 *	comedi_insn structure
 *	data (for writes) from insn->data pointer
 *
 * writes:
 *	data (for reads) to insn->data pointer
 */
static int do_insn_ioctl(struct comedi_device *dev,
			 struct comedi_insn *insn, void *file)
{
	unsigned int *data = NULL;
	unsigned int n_data = MIN_SAMPLES;
	int ret = 0;

	lockdep_assert_held(&dev->mutex);

	n_data = max(n_data, insn->n);

	/* This is where the behavior of insn and insnlist deviate. */
	if (insn->n > MAX_SAMPLES) {
		insn->n = MAX_SAMPLES;
		n_data = MAX_SAMPLES;
	}

	data = kmalloc_array(n_data, sizeof(unsigned int), GFP_KERNEL);
	if (!data) {
		ret = -ENOMEM;
		goto error;
	}

	if (insn->insn & INSN_MASK_WRITE) {
		if (copy_from_user(data,
				   insn->data,
				   insn->n * sizeof(unsigned int))) {
			ret = -EFAULT;
			goto error;
		}
	}
	ret = parse_insn(dev, insn, data, file);
	if (ret < 0)
		goto error;
	if (insn->insn & INSN_MASK_READ) {
		if (copy_to_user(insn->data,
				 data,
				 insn->n * sizeof(unsigned int))) {
			ret = -EFAULT;
			goto error;
		}
	}
	ret = insn->n;

error:
	kfree(data);

	return ret;
}

static int __comedi_get_user_cmd(struct comedi_device *dev,
				 struct comedi_cmd *cmd)
{
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);
	if (cmd->subdev >= dev->n_subdevices) {
		dev_dbg(dev->class_dev, "%d no such subdevice\n", cmd->subdev);
		return -ENODEV;
	}

	s = &dev->subdevices[cmd->subdev];

	if (s->type == COMEDI_SUBD_UNUSED) {
		dev_dbg(dev->class_dev, "%d not valid subdevice\n",
			cmd->subdev);
		return -EIO;
	}

	if (!s->do_cmd || !s->do_cmdtest || !s->async) {
		dev_dbg(dev->class_dev,
			"subdevice %d does not support commands\n",
			cmd->subdev);
		return -EIO;
	}

	/* make sure channel/gain list isn't too long */
	if (cmd->chanlist_len > s->len_chanlist) {
		dev_dbg(dev->class_dev, "channel/gain list too long %d > %d\n",
			cmd->chanlist_len, s->len_chanlist);
		return -EINVAL;
	}

	/*
	 * Set the CMDF_WRITE flag to the correct state if the subdevice
	 * supports only "read" commands or only "write" commands.
	 */
	switch (s->subdev_flags & (SDF_CMD_READ | SDF_CMD_WRITE)) {
	case SDF_CMD_READ:
		cmd->flags &= ~CMDF_WRITE;
		break;
	case SDF_CMD_WRITE:
		cmd->flags |= CMDF_WRITE;
		break;
	default:
		break;
	}

	return 0;
}

static int __comedi_get_user_chanlist(struct comedi_device *dev,
				      struct comedi_subdevice *s,
				      unsigned int __user *user_chanlist,
				      struct comedi_cmd *cmd)
{
	unsigned int *chanlist;
	int ret;

	lockdep_assert_held(&dev->mutex);
	cmd->chanlist = NULL;
	chanlist = memdup_array_user(user_chanlist,
				     cmd->chanlist_len, sizeof(unsigned int));
	if (IS_ERR(chanlist))
		return PTR_ERR(chanlist);

	/* make sure each element in channel/gain list is valid */
	ret = comedi_check_chanlist(s, cmd->chanlist_len, chanlist);
	if (ret < 0) {
		kfree(chanlist);
		return ret;
	}

	cmd->chanlist = chanlist;

	return 0;
}

/*
 * COMEDI_CMD ioctl
 * asynchronous acquisition command set-up
 *
 * arg:
 *	pointer to comedi_cmd structure
 *
 * reads:
 *	comedi_cmd structure
 *	channel/range list from cmd->chanlist pointer
 *
 * writes:
 *	possibly modified comedi_cmd structure (when -EAGAIN returned)
 */
static int do_cmd_ioctl(struct comedi_device *dev,
			struct comedi_cmd *cmd, bool *copy, void *file)
{
	struct comedi_subdevice *s;
	struct comedi_async *async;
	unsigned int __user *user_chanlist;
	int ret;

	lockdep_assert_held(&dev->mutex);

	/* do some simple cmd validation */
	ret = __comedi_get_user_cmd(dev, cmd);
	if (ret)
		return ret;

	/* save user's chanlist pointer so it can be restored later */
	user_chanlist = (unsigned int __user *)cmd->chanlist;

	s = &dev->subdevices[cmd->subdev];
	async = s->async;

	/* are we locked? (ioctl lock) */
	if (s->lock && s->lock != file) {
		dev_dbg(dev->class_dev, "subdevice locked\n");
		return -EACCES;
	}

	/* are we busy? */
	if (s->busy) {
		dev_dbg(dev->class_dev, "subdevice busy\n");
		return -EBUSY;
	}

	/* make sure channel/gain list isn't too short */
	if (cmd->chanlist_len < 1) {
		dev_dbg(dev->class_dev, "channel/gain list too short %u < 1\n",
			cmd->chanlist_len);
		return -EINVAL;
	}

	async->cmd = *cmd;
	async->cmd.data = NULL;

	/* load channel/gain list */
	ret = __comedi_get_user_chanlist(dev, s, user_chanlist, &async->cmd);
	if (ret)
		goto cleanup;

	ret = s->do_cmdtest(dev, s, &async->cmd);

	if (async->cmd.flags & CMDF_BOGUS || ret) {
		dev_dbg(dev->class_dev, "test returned %d\n", ret);
		*cmd = async->cmd;
		/* restore chanlist pointer before copying back */
		cmd->chanlist = (unsigned int __force *)user_chanlist;
		cmd->data = NULL;
		*copy = true;
		ret = -EAGAIN;
		goto cleanup;
	}

	if (!async->prealloc_bufsz) {
		ret = -ENOMEM;
		dev_dbg(dev->class_dev, "no buffer (?)\n");
		goto cleanup;
	}

	comedi_buf_reset(s);

	async->cb_mask = COMEDI_CB_BLOCK | COMEDI_CB_CANCEL_MASK;
	if (async->cmd.flags & CMDF_WAKE_EOS)
		async->cb_mask |= COMEDI_CB_EOS;

	comedi_update_subdevice_runflags(s, COMEDI_SRF_BUSY_MASK,
					 COMEDI_SRF_RUNNING);

	/*
	 * Set s->busy _after_ setting COMEDI_SRF_RUNNING flag to avoid
	 * race with comedi_read() or comedi_write().
	 */
	s->busy = file;
	ret = s->do_cmd(dev, s);
	if (ret == 0)
		return 0;

cleanup:
	do_become_nonbusy(dev, s);

	return ret;
}

/*
 * COMEDI_CMDTEST ioctl
 * asynchronous acquisition command testing
 *
 * arg:
 *	pointer to comedi_cmd structure
 *
 * reads:
 *	comedi_cmd structure
 *	channel/range list from cmd->chanlist pointer
 *
 * writes:
 *	possibly modified comedi_cmd structure
 */
static int do_cmdtest_ioctl(struct comedi_device *dev,
			    struct comedi_cmd *cmd, bool *copy, void *file)
{
	struct comedi_subdevice *s;
	unsigned int __user *user_chanlist;
	int ret;

	lockdep_assert_held(&dev->mutex);

	/* do some simple cmd validation */
	ret = __comedi_get_user_cmd(dev, cmd);
	if (ret)
		return ret;

	/* save user's chanlist pointer so it can be restored later */
	user_chanlist = (unsigned int __user *)cmd->chanlist;

	s = &dev->subdevices[cmd->subdev];

	/* user_chanlist can be NULL for COMEDI_CMDTEST ioctl */
	if (user_chanlist) {
		/* load channel/gain list */
		ret = __comedi_get_user_chanlist(dev, s, user_chanlist, cmd);
		if (ret)
			return ret;
	}

	ret = s->do_cmdtest(dev, s, cmd);

	kfree(cmd->chanlist);	/* free kernel copy of user chanlist */

	/* restore chanlist pointer before copying back */
	cmd->chanlist = (unsigned int __force *)user_chanlist;
	*copy = true;

	return ret;
}

/*
 * COMEDI_LOCK ioctl
 * lock subdevice
 *
 * arg:
 *	subdevice number
 *
 * reads:
 *	nothing
 *
 * writes:
 *	nothing
 */
static int do_lock_ioctl(struct comedi_device *dev, unsigned long arg,
			 void *file)
{
	int ret = 0;
	unsigned long flags;
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);
	if (arg >= dev->n_subdevices)
		return -EINVAL;
	s = &dev->subdevices[arg];

	spin_lock_irqsave(&s->spin_lock, flags);
	if (s->busy || s->lock)
		ret = -EBUSY;
	else
		s->lock = file;
	spin_unlock_irqrestore(&s->spin_lock, flags);

	return ret;
}

/*
 * COMEDI_UNLOCK ioctl
 * unlock subdevice
 *
 * arg:
 *	subdevice number
 *
 * reads:
 *	nothing
 *
 * writes:
 *	nothing
 */
static int do_unlock_ioctl(struct comedi_device *dev, unsigned long arg,
			   void *file)
{
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);
	if (arg >= dev->n_subdevices)
		return -EINVAL;
	s = &dev->subdevices[arg];

	if (s->busy)
		return -EBUSY;

	if (s->lock && s->lock != file)
		return -EACCES;

	if (s->lock == file)
		s->lock = NULL;

	return 0;
}

/*
 * COMEDI_CANCEL ioctl
 * cancel asynchronous acquisition
 *
 * arg:
 *	subdevice number
 *
 * reads:
 *	nothing
 *
 * writes:
 *	nothing
 */
static int do_cancel_ioctl(struct comedi_device *dev, unsigned long arg,
			   void *file)
{
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);
	if (arg >= dev->n_subdevices)
		return -EINVAL;
	s = &dev->subdevices[arg];
	if (!s->async)
		return -EINVAL;

	if (!s->busy)
		return 0;

	if (s->busy != file)
		return -EBUSY;

	return do_cancel(dev, s);
}

/*
 * COMEDI_POLL ioctl
 * instructs driver to synchronize buffers
 *
 * arg:
 *	subdevice number
 *
 * reads:
 *	nothing
 *
 * writes:
 *	nothing
 */
static int do_poll_ioctl(struct comedi_device *dev, unsigned long arg,
			 void *file)
{
	struct comedi_subdevice *s;

	lockdep_assert_held(&dev->mutex);
	if (arg >= dev->n_subdevices)
		return -EINVAL;
	s = &dev->subdevices[arg];

	if (!s->busy)
		return 0;

	if (s->busy != file)
		return -EBUSY;

	if (s->poll)
		return s->poll(dev, s);

	return -EINVAL;
}

/*
 * COMEDI_SETRSUBD ioctl
 * sets the current "read" subdevice on a per-file basis
 *
 * arg:
 *	subdevice number
 *
 * reads:
 *	nothing
 *
 * writes:
 *	nothing
 */
static int do_setrsubd_ioctl(struct comedi_device *dev, unsigned long arg,
			     struct file *file)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_subdevice *s_old, *s_new;

	lockdep_assert_held(&dev->mutex);
	if (arg >= dev->n_subdevices)
		return -EINVAL;

	s_new = &dev->subdevices[arg];
	s_old = comedi_file_read_subdevice(file);
	if (s_old == s_new)
		return 0;	/* no change */

	if (!(s_new->subdev_flags & SDF_CMD_READ))
		return -EINVAL;

	/*
	 * Check the file isn't still busy handling a "read" command on the
	 * old subdevice (if any).
	 */
	if (s_old && s_old->busy == file && s_old->async &&
	    !(s_old->async->cmd.flags & CMDF_WRITE))
		return -EBUSY;

	WRITE_ONCE(cfp->read_subdev, s_new);
	return 0;
}

/*
 * COMEDI_SETWSUBD ioctl
 * sets the current "write" subdevice on a per-file basis
 *
 * arg:
 *	subdevice number
 *
 * reads:
 *	nothing
 *
 * writes:
 *	nothing
 */
static int do_setwsubd_ioctl(struct comedi_device *dev, unsigned long arg,
			     struct file *file)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_subdevice *s_old, *s_new;

	lockdep_assert_held(&dev->mutex);
	if (arg >= dev->n_subdevices)
		return -EINVAL;

	s_new = &dev->subdevices[arg];
	s_old = comedi_file_write_subdevice(file);
	if (s_old == s_new)
		return 0;	/* no change */

	if (!(s_new->subdev_flags & SDF_CMD_WRITE))
		return -EINVAL;

	/*
	 * Check the file isn't still busy handling a "write" command on the
	 * old subdevice (if any).
	 */
	if (s_old && s_old->busy == file && s_old->async &&
	    (s_old->async->cmd.flags & CMDF_WRITE))
		return -EBUSY;

	WRITE_ONCE(cfp->write_subdev, s_new);
	return 0;
}

static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
				  unsigned long arg)
{
	unsigned int minor = iminor(file_inode(file));
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	int rc;

	mutex_lock(&dev->mutex);

	/*
	 * Device config is special, because it must work on
	 * an unconfigured device.
	 */
	if (cmd == COMEDI_DEVCONFIG) {
		if (minor >= COMEDI_NUM_BOARD_MINORS) {
			/* Device config not appropriate on non-board minors. */
			rc = -ENOTTY;
			goto done;
		}
		rc = do_devconfig_ioctl(dev,
					(struct comedi_devconfig __user *)arg);
		if (rc == 0) {
			if (arg == 0 &&
			    dev->minor >= comedi_num_legacy_minors) {
				/*
				 * Successfully unconfigured a dynamically
				 * allocated device.  Try and remove it.
				 */
				if (comedi_clear_board_dev(dev)) {
					mutex_unlock(&dev->mutex);
					comedi_free_board_dev(dev);
					return rc;
				}
			}
		}
		goto done;
	}

	if (!dev->attached) {
		dev_dbg(dev->class_dev, "no driver attached\n");
		rc = -ENODEV;
		goto done;
	}

	switch (cmd) {
	case COMEDI_BUFCONFIG:
		rc = do_bufconfig_ioctl(dev,
					(struct comedi_bufconfig __user *)arg);
		break;
	case COMEDI_DEVINFO:
		rc = do_devinfo_ioctl(dev, (struct comedi_devinfo __user *)arg,
				      file);
		break;
	case COMEDI_SUBDINFO:
		rc = do_subdinfo_ioctl(dev,
				       (struct comedi_subdinfo __user *)arg,
				       file);
		break;
	case COMEDI_CHANINFO: {
		struct comedi_chaninfo it;

		if (copy_from_user(&it, (void __user *)arg, sizeof(it)))
			rc = -EFAULT;
		else
			rc = do_chaninfo_ioctl(dev, &it);
		break;
	}
	case COMEDI_RANGEINFO: {
		struct comedi_rangeinfo it;

		if (copy_from_user(&it, (void __user *)arg, sizeof(it)))
			rc = -EFAULT;
		else
			rc = do_rangeinfo_ioctl(dev, &it);
		break;
	}
	case COMEDI_BUFINFO:
		rc = do_bufinfo_ioctl(dev,
				      (struct comedi_bufinfo __user *)arg,
				      file);
		break;
	case COMEDI_LOCK:
		rc = do_lock_ioctl(dev, arg, file);
		break;
	case COMEDI_UNLOCK:
		rc = do_unlock_ioctl(dev, arg, file);
		break;
	case COMEDI_CANCEL:
		rc = do_cancel_ioctl(dev, arg, file);
		break;
	case COMEDI_CMD: {
		struct comedi_cmd cmd;
		bool copy = false;

		if (copy_from_user(&cmd, (void __user *)arg, sizeof(cmd))) {
			rc = -EFAULT;
			break;
		}
		rc = do_cmd_ioctl(dev, &cmd, &copy, file);
		if (copy && copy_to_user((void __user *)arg, &cmd, sizeof(cmd)))
			rc = -EFAULT;
		break;
	}
	case COMEDI_CMDTEST: {
		struct comedi_cmd cmd;
		bool copy = false;

		if (copy_from_user(&cmd, (void __user *)arg, sizeof(cmd))) {
			rc = -EFAULT;
			break;
		}
		rc = do_cmdtest_ioctl(dev, &cmd, &copy, file);
		if (copy && copy_to_user((void __user *)arg, &cmd, sizeof(cmd)))
			rc = -EFAULT;
		break;
	}
	case COMEDI_INSNLIST: {
		struct comedi_insnlist insnlist;
		struct comedi_insn *insns = NULL;

		if (copy_from_user(&insnlist, (void __user *)arg,
				   sizeof(insnlist))) {
			rc = -EFAULT;
			break;
		}
		insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL);
		if (!insns) {
			rc = -ENOMEM;
			break;
		}
		if (copy_from_user(insns, insnlist.insns,
				   sizeof(*insns) * insnlist.n_insns)) {
			rc = -EFAULT;
			kfree(insns);
			break;
		}
		rc = do_insnlist_ioctl(dev, insns, insnlist.n_insns, file);
		kfree(insns);
		break;
	}
	case COMEDI_INSN: {
		struct comedi_insn insn;

		if (copy_from_user(&insn, (void __user *)arg, sizeof(insn)))
			rc = -EFAULT;
		else
			rc = do_insn_ioctl(dev, &insn, file);
		break;
	}
	case COMEDI_POLL:
		rc = do_poll_ioctl(dev, arg, file);
		break;
	case COMEDI_SETRSUBD:
		rc = do_setrsubd_ioctl(dev, arg, file);
		break;
	case COMEDI_SETWSUBD:
		rc = do_setwsubd_ioctl(dev, arg, file);
		break;
	default:
		rc = -ENOTTY;
		break;
	}

done:
	mutex_unlock(&dev->mutex);
	return rc;
}

static void comedi_vm_open(struct vm_area_struct *area)
{
	struct comedi_buf_map *bm;

	bm = area->vm_private_data;
	comedi_buf_map_get(bm);
}

static void comedi_vm_close(struct vm_area_struct *area)
{
	struct comedi_buf_map *bm;

	bm = area->vm_private_data;
	comedi_buf_map_put(bm);
}

static int comedi_vm_access(struct vm_area_struct *vma, unsigned long addr,
			    void *buf, int len, int write)
{
	struct comedi_buf_map *bm = vma->vm_private_data;
	unsigned long offset =
	    addr - vma->vm_start + (vma->vm_pgoff << PAGE_SHIFT);

	if (len < 0)
		return -EINVAL;
	if (len > vma->vm_end - addr)
		len = vma->vm_end - addr;
	return comedi_buf_map_access(bm, offset, buf, len, write);
}

static const struct vm_operations_struct comedi_vm_ops = {
	.open = comedi_vm_open,
	.close = comedi_vm_close,
	.access = comedi_vm_access,
};

static int comedi_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi_subdevice *s;
	struct comedi_async *async;
	struct comedi_buf_map *bm = NULL;
	struct comedi_buf_page *buf;
	unsigned long start = vma->vm_start;
	unsigned long size;
	int n_pages;
	int i;
	int retval = 0;

	/*
	 * 'trylock' avoids circular dependency with current->mm->mmap_lock
	 * and down-reading &dev->attach_lock should normally succeed without
	 * contention unless the device is in the process of being attached
	 * or detached.
	 */
	if (!down_read_trylock(&dev->attach_lock))
		return -EAGAIN;

	if (!dev->attached) {
		dev_dbg(dev->class_dev, "no driver attached\n");
		retval = -ENODEV;
		goto done;
	}

	if (vma->vm_flags & VM_WRITE)
		s = comedi_file_write_subdevice(file);
	else
		s = comedi_file_read_subdevice(file);
	if (!s) {
		retval = -EINVAL;
		goto done;
	}

	async = s->async;
	if (!async) {
		retval = -EINVAL;
		goto done;
	}

	if (vma->vm_pgoff != 0) {
		dev_dbg(dev->class_dev, "mmap() offset must be 0.\n");
		retval = -EINVAL;
		goto done;
	}

	size = vma->vm_end - vma->vm_start;
	if (size > async->prealloc_bufsz) {
		retval = -EFAULT;
		goto done;
	}
	if (offset_in_page(size)) {
		retval = -EFAULT;
		goto done;
	}

	n_pages = vma_pages(vma);

	/* get reference to current buf map (if any) */
	bm = comedi_buf_map_from_subdev_get(s);
	if (!bm || n_pages > bm->n_pages) {
		retval = -EINVAL;
		goto done;
	}
	if (bm->dma_dir != DMA_NONE) {
		/*
		 * DMA buffer was allocated as a single block.
		 * Address is in page_list[0].
		 */
		buf = &bm->page_list[0];
		retval = dma_mmap_coherent(bm->dma_hw_dev, vma, buf->virt_addr,
					   buf->dma_addr, n_pages * PAGE_SIZE);
	} else {
		for (i = 0; i < n_pages; ++i) {
			unsigned long pfn;

			buf = &bm->page_list[i];
			pfn = page_to_pfn(virt_to_page(buf->virt_addr));
			retval = remap_pfn_range(vma, start, pfn, PAGE_SIZE,
						 PAGE_SHARED);
			if (retval)
				break;

			start += PAGE_SIZE;
		}

#ifdef CONFIG_MMU
		/*
		 * Leaving behind a partial mapping of a buffer we're about to
		 * drop is unsafe, see remap_pfn_range_notrack().
		 * We need to zap the range here ourselves instead of relying
		 * on the automatic zapping in remap_pfn_range() because we call
		 * remap_pfn_range() in a loop.
		 */
		if (retval)
			zap_vma_ptes(vma, vma->vm_start, size);
#endif
	}

	if (retval == 0) {
		vma->vm_ops = &comedi_vm_ops;
		vma->vm_private_data = bm;

		vma->vm_ops->open(vma);
	}

done:
	up_read(&dev->attach_lock);
	comedi_buf_map_put(bm);	/* put reference to buf map - okay if NULL */
	return retval;
}

static __poll_t comedi_poll(struct file *file, poll_table *wait)
{
	__poll_t mask = 0;
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi_subdevice *s, *s_read;

	down_read(&dev->attach_lock);

	if (!dev->attached) {
		dev_dbg(dev->class_dev, "no driver attached\n");
		goto done;
	}

	s = comedi_file_read_subdevice(file);
	s_read = s;
	if (s && s->async) {
		poll_wait(file, &s->async->wait_head, wait);
		if (s->busy != file || !comedi_is_subdevice_running(s) ||
		    (s->async->cmd.flags & CMDF_WRITE) ||
		    comedi_buf_read_n_available(s) > 0)
			mask |= EPOLLIN | EPOLLRDNORM;
	}

	s = comedi_file_write_subdevice(file);
	if (s && s->async) {
		unsigned int bps = comedi_bytes_per_sample(s);

		if (s != s_read)
			poll_wait(file, &s->async->wait_head, wait);
		if (s->busy != file || !comedi_is_subdevice_running(s) ||
		    !(s->async->cmd.flags & CMDF_WRITE) ||
		    comedi_buf_write_n_available(s) >= bps)
			mask |= EPOLLOUT | EPOLLWRNORM;
	}

done:
	up_read(&dev->attach_lock);
	return mask;
}

static ssize_t comedi_write(struct file *file, const char __user *buf,
			    size_t nbytes, loff_t *offset)
{
	struct comedi_subdevice *s;
	struct comedi_async *async;
	unsigned int n, m;
	ssize_t count = 0;
	int retval = 0;
	DECLARE_WAITQUEUE(wait, current);
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	bool become_nonbusy = false;
	bool attach_locked;
	unsigned int old_detach_count;

	/* Protect against device detachment during operation. */
	down_read(&dev->attach_lock);
	attach_locked = true;
	old_detach_count = dev->detach_count;

	if (!dev->attached) {
		dev_dbg(dev->class_dev, "no driver attached\n");
		retval = -ENODEV;
		goto out;
	}

	s = comedi_file_write_subdevice(file);
	if (!s || !s->async) {
		retval = -EIO;
		goto out;
	}

	async = s->async;
	if (s->busy != file || !(async->cmd.flags & CMDF_WRITE)) {
		retval = -EINVAL;
		goto out;
	}

	add_wait_queue(&async->wait_head, &wait);
	while (count == 0 && !retval) {
		unsigned int runflags;
		unsigned int wp, n1, n2;

		set_current_state(TASK_INTERRUPTIBLE);

		runflags = comedi_get_subdevice_runflags(s);
		if (!comedi_is_runflags_running(runflags)) {
			if (comedi_is_runflags_in_error(runflags))
				retval = -EPIPE;
			if (retval || nbytes)
				become_nonbusy = true;
			break;
		}
		if (nbytes == 0)
			break;

		/* Allocate all free buffer space. */
		comedi_buf_write_alloc(s, async->prealloc_bufsz);
		m = comedi_buf_write_n_allocated(s);
		n = min_t(size_t, m, nbytes);

		if (n == 0) {
			if (file->f_flags & O_NONBLOCK) {
				retval = -EAGAIN;
				break;
			}
			schedule();
			if (signal_pending(current)) {
				retval = -ERESTARTSYS;
				break;
			}
			if (s->busy != file ||
			    !(async->cmd.flags & CMDF_WRITE)) {
				retval = -EINVAL;
				break;
			}
			continue;
		}

		set_current_state(TASK_RUNNING);
		wp = async->buf_write_ptr;
		n1 = min(n, async->prealloc_bufsz - wp);
		n2 = n - n1;
		m = copy_from_user(async->prealloc_buf + wp, buf, n1);
		if (m)
			m += n2;
		else if (n2)
			m = copy_from_user(async->prealloc_buf, buf + n1, n2);
		if (m) {
			n -= m;
			retval = -EFAULT;
		}
		comedi_buf_write_free(s, n);

		count += n;
		nbytes -= n;

		buf += n;
	}
	remove_wait_queue(&async->wait_head, &wait);
	set_current_state(TASK_RUNNING);
	if (become_nonbusy && count == 0) {
		struct comedi_subdevice *new_s;

		/*
		 * To avoid deadlock, cannot acquire dev->mutex
		 * while dev->attach_lock is held.
		 */
		up_read(&dev->attach_lock);
		attach_locked = false;
		mutex_lock(&dev->mutex);
		/*
		 * Check device hasn't become detached behind our back.
		 * Checking dev->detach_count is unchanged ought to be
		 * sufficient (unless there have been 2**32 detaches in the
		 * meantime!), but check the subdevice pointer as well just in
		 * case.
		 *
		 * Also check the subdevice is still in a suitable state to
		 * become non-busy in case it changed behind our back.
		 */
		new_s = comedi_file_write_subdevice(file);
		if (dev->attached && old_detach_count == dev->detach_count &&
		    s == new_s && new_s->async == async && s->busy == file &&
		    (async->cmd.flags & CMDF_WRITE) &&
		    !comedi_is_subdevice_running(s))
			do_become_nonbusy(dev, s);
		mutex_unlock(&dev->mutex);
	}
out:
	if (attach_locked)
		up_read(&dev->attach_lock);

	return count ? count : retval;
}

static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
			   loff_t *offset)
{
	struct comedi_subdevice *s;
	struct comedi_async *async;
	unsigned int n, m;
	ssize_t count = 0;
	int retval = 0;
	DECLARE_WAITQUEUE(wait, current);
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	unsigned int old_detach_count;
	bool become_nonbusy = false;
	bool attach_locked;

	/* Protect against device detachment during operation. */
	down_read(&dev->attach_lock);
	attach_locked = true;
	old_detach_count = dev->detach_count;

	if (!dev->attached) {
		dev_dbg(dev->class_dev, "no driver attached\n");
		retval = -ENODEV;
		goto out;
	}

	s = comedi_file_read_subdevice(file);
	if (!s || !s->async) {
		retval = -EIO;
		goto out;
	}

	async = s->async;
	if (s->busy != file || (async->cmd.flags & CMDF_WRITE)) {
		retval = -EINVAL;
		goto out;
	}

	add_wait_queue(&async->wait_head, &wait);
	while (count == 0 && !retval) {
		unsigned int rp, n1, n2;

		set_current_state(TASK_INTERRUPTIBLE);

		m = comedi_buf_read_n_available(s);
		n = min_t(size_t, m, nbytes);

		if (n == 0) {
			unsigned int runflags =
				     comedi_get_subdevice_runflags(s);

			if (!comedi_is_runflags_running(runflags)) {
				if (comedi_is_runflags_in_error(runflags))
					retval = -EPIPE;
				if (retval || nbytes)
					become_nonbusy = true;
				break;
			}
			if (nbytes == 0)
				break;
			if (file->f_flags & O_NONBLOCK) {
				retval = -EAGAIN;
				break;
			}
			schedule();
			if (signal_pending(current)) {
				retval = -ERESTARTSYS;
				break;
			}
			if (s->busy != file ||
			    (async->cmd.flags & CMDF_WRITE)) {
				retval = -EINVAL;
				break;
			}
			continue;
		}

		set_current_state(TASK_RUNNING);
		rp = async->buf_read_ptr;
		n1 = min(n, async->prealloc_bufsz - rp);
		n2 = n - n1;
		m = copy_to_user(buf, async->prealloc_buf + rp, n1);
		if (m)
			m += n2;
		else if (n2)
			m = copy_to_user(buf + n1, async->prealloc_buf, n2);
		if (m) {
			n -= m;
			retval = -EFAULT;
		}

		comedi_buf_read_alloc(s, n);
		comedi_buf_read_free(s, n);

		count += n;
		nbytes -= n;

		buf += n;
	}
	remove_wait_queue(&async->wait_head, &wait);
	set_current_state(TASK_RUNNING);
	if (become_nonbusy && count == 0) {
		struct comedi_subdevice *new_s;

		/*
		 * To avoid deadlock, cannot acquire dev->mutex
		 * while dev->attach_lock is held.
		 */
		up_read(&dev->attach_lock);
		attach_locked = false;
		mutex_lock(&dev->mutex);
		/*
		 * Check device hasn't become detached behind our back.
		 * Checking dev->detach_count is unchanged ought to be
		 * sufficient (unless there have been 2**32 detaches in the
		 * meantime!), but check the subdevice pointer as well just in
		 * case.
		 *
		 * Also check the subdevice is still in a suitable state to
		 * become non-busy in case it changed behind our back.
		 */
		new_s = comedi_file_read_subdevice(file);
		if (dev->attached && old_detach_count == dev->detach_count &&
		    s == new_s && new_s->async == async && s->busy == file &&
		    !(async->cmd.flags & CMDF_WRITE) &&
		    !comedi_is_subdevice_running(s) &&
		    comedi_buf_read_n_available(s) == 0)
			do_become_nonbusy(dev, s);
		mutex_unlock(&dev->mutex);
	}
out:
	if (attach_locked)
		up_read(&dev->attach_lock);

	return count ? count : retval;
}

static int comedi_open(struct inode *inode, struct file *file)
{
	const unsigned int minor = iminor(inode);
	struct comedi_file *cfp;
	struct comedi_device *dev = comedi_dev_get_from_minor(minor);
	int rc;

	if (!dev) {
		pr_debug("invalid minor number\n");
		return -ENODEV;
	}

	cfp = kzalloc(sizeof(*cfp), GFP_KERNEL);
	if (!cfp) {
		comedi_dev_put(dev);
		return -ENOMEM;
	}

	cfp->dev = dev;

	mutex_lock(&dev->mutex);
	if (!dev->attached && !capable(CAP_SYS_ADMIN)) {
		dev_dbg(dev->class_dev, "not attached and not CAP_SYS_ADMIN\n");
		rc = -ENODEV;
		goto out;
	}
	if (dev->attached && dev->use_count == 0) {
		if (!try_module_get(dev->driver->module)) {
			rc = -ENXIO;
			goto out;
		}
		if (dev->open) {
			rc = dev->open(dev);
			if (rc < 0) {
				module_put(dev->driver->module);
				goto out;
			}
		}
	}

	dev->use_count++;
	file->private_data = cfp;
	comedi_file_reset(file);
	rc = 0;

out:
	mutex_unlock(&dev->mutex);
	if (rc) {
		comedi_dev_put(dev);
		kfree(cfp);
	}
	return rc;
}

static int comedi_fasync(int fd, struct file *file, int on)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;

	return fasync_helper(fd, file, on, &dev->async_queue);
}

static int comedi_close(struct inode *inode, struct file *file)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi_subdevice *s = NULL;
	int i;

	mutex_lock(&dev->mutex);

	if (dev->subdevices) {
		for (i = 0; i < dev->n_subdevices; i++) {
			s = &dev->subdevices[i];

			if (s->busy == file)
				do_cancel(dev, s);
			if (s->lock == file)
				s->lock = NULL;
		}
	}
	if (dev->attached && dev->use_count == 1) {
		if (dev->close)
			dev->close(dev);
		module_put(dev->driver->module);
	}

	dev->use_count--;

	mutex_unlock(&dev->mutex);
	comedi_dev_put(dev);
	kfree(cfp);

	return 0;
}

#ifdef CONFIG_COMPAT

#define COMEDI32_CHANINFO _IOR(CIO, 3, struct comedi32_chaninfo_struct)
#define COMEDI32_RANGEINFO _IOR(CIO, 8, struct comedi32_rangeinfo_struct)
/*
 * N.B. COMEDI32_CMD and COMEDI_CMD ought to use _IOWR, not _IOR.
 * It's too late to change it now, but it only affects the command number.
 */
#define COMEDI32_CMD _IOR(CIO, 9, struct comedi32_cmd_struct)
/*
 * N.B. COMEDI32_CMDTEST and COMEDI_CMDTEST ought to use _IOWR, not _IOR.
 * It's too late to change it now, but it only affects the command number.
 */
#define COMEDI32_CMDTEST _IOR(CIO, 10, struct comedi32_cmd_struct)
#define COMEDI32_INSNLIST _IOR(CIO, 11, struct comedi32_insnlist_struct)
#define COMEDI32_INSN _IOR(CIO, 12, struct comedi32_insn_struct)

struct comedi32_chaninfo_struct {
	unsigned int subdev;
	compat_uptr_t maxdata_list;	/* 32-bit 'unsigned int *' */
	compat_uptr_t flaglist;	/* 32-bit 'unsigned int *' */
	compat_uptr_t rangelist;	/* 32-bit 'unsigned int *' */
	unsigned int unused[4];
};

struct comedi32_rangeinfo_struct {
	unsigned int range_type;
	compat_uptr_t range_ptr;	/* 32-bit 'void *' */
};

struct comedi32_cmd_struct {
	unsigned int subdev;
	unsigned int flags;
	unsigned int start_src;
	unsigned int start_arg;
	unsigned int scan_begin_src;
	unsigned int scan_begin_arg;
	unsigned int convert_src;
	unsigned int convert_arg;
	unsigned int scan_end_src;
	unsigned int scan_end_arg;
	unsigned int stop_src;
	unsigned int stop_arg;
	compat_uptr_t chanlist;	/* 32-bit 'unsigned int *' */
	unsigned int chanlist_len;
	compat_uptr_t data;	/* 32-bit 'short *' */
	unsigned int data_len;
};

struct comedi32_insn_struct {
	unsigned int insn;
	unsigned int n;
	compat_uptr_t data;	/* 32-bit 'unsigned int *' */
	unsigned int subdev;
	unsigned int chanspec;
	unsigned int unused[3];
};

struct comedi32_insnlist_struct {
	unsigned int n_insns;
	compat_uptr_t insns;	/* 32-bit 'struct comedi_insn *' */
};

/* Handle 32-bit COMEDI_CHANINFO ioctl. */
static int compat_chaninfo(struct file *file, unsigned long arg)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi32_chaninfo_struct chaninfo32;
	struct comedi_chaninfo chaninfo;
	int err;

	if (copy_from_user(&chaninfo32, compat_ptr(arg), sizeof(chaninfo32)))
		return -EFAULT;

	memset(&chaninfo, 0, sizeof(chaninfo));
	chaninfo.subdev = chaninfo32.subdev;
	chaninfo.maxdata_list = compat_ptr(chaninfo32.maxdata_list);
	chaninfo.flaglist = compat_ptr(chaninfo32.flaglist);
	chaninfo.rangelist = compat_ptr(chaninfo32.rangelist);

	mutex_lock(&dev->mutex);
	err = do_chaninfo_ioctl(dev, &chaninfo);
	mutex_unlock(&dev->mutex);
	return err;
}

/* Handle 32-bit COMEDI_RANGEINFO ioctl. */
static int compat_rangeinfo(struct file *file, unsigned long arg)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi32_rangeinfo_struct rangeinfo32;
	struct comedi_rangeinfo rangeinfo;
	int err;

	if (copy_from_user(&rangeinfo32, compat_ptr(arg), sizeof(rangeinfo32)))
		return -EFAULT;
	memset(&rangeinfo, 0, sizeof(rangeinfo));
	rangeinfo.range_type = rangeinfo32.range_type;
	rangeinfo.range_ptr = compat_ptr(rangeinfo32.range_ptr);

	mutex_lock(&dev->mutex);
	err = do_rangeinfo_ioctl(dev, &rangeinfo);
	mutex_unlock(&dev->mutex);
	return err;
}

/* Copy 32-bit cmd structure to native cmd structure. */
static int get_compat_cmd(struct comedi_cmd *cmd,
			  struct comedi32_cmd_struct __user *cmd32)
{
	struct comedi32_cmd_struct v32;

	if (copy_from_user(&v32, cmd32, sizeof(v32)))
		return -EFAULT;

	cmd->subdev = v32.subdev;
	cmd->flags = v32.flags;
	cmd->start_src = v32.start_src;
	cmd->start_arg = v32.start_arg;
	cmd->scan_begin_src = v32.scan_begin_src;
	cmd->scan_begin_arg = v32.scan_begin_arg;
	cmd->convert_src = v32.convert_src;
	cmd->convert_arg = v32.convert_arg;
	cmd->scan_end_src = v32.scan_end_src;
	cmd->scan_end_arg = v32.scan_end_arg;
	cmd->stop_src = v32.stop_src;
	cmd->stop_arg = v32.stop_arg;
	cmd->chanlist = (unsigned int __force *)compat_ptr(v32.chanlist);
	cmd->chanlist_len = v32.chanlist_len;
	cmd->data = compat_ptr(v32.data);
	cmd->data_len = v32.data_len;
	return 0;
}

/* Copy native cmd structure to 32-bit cmd structure. */
static int put_compat_cmd(struct comedi32_cmd_struct __user *cmd32,
			  struct comedi_cmd *cmd)
{
	struct comedi32_cmd_struct v32;

	memset(&v32, 0, sizeof(v32));
	v32.subdev = cmd->subdev;
	v32.flags = cmd->flags;
	v32.start_src = cmd->start_src;
	v32.start_arg = cmd->start_arg;
	v32.scan_begin_src = cmd->scan_begin_src;
	v32.scan_begin_arg = cmd->scan_begin_arg;
	v32.convert_src = cmd->convert_src;
	v32.convert_arg = cmd->convert_arg;
	v32.scan_end_src = cmd->scan_end_src;
	v32.scan_end_arg = cmd->scan_end_arg;
	v32.stop_src = cmd->stop_src;
	v32.stop_arg = cmd->stop_arg;
	/* Assume chanlist pointer is unchanged. */
	v32.chanlist = ptr_to_compat((unsigned int __user *)cmd->chanlist);
	v32.chanlist_len = cmd->chanlist_len;
	v32.data = ptr_to_compat(cmd->data);
	v32.data_len = cmd->data_len;
	if (copy_to_user(cmd32, &v32, sizeof(v32)))
		return -EFAULT;
	return 0;
}

/* Handle 32-bit COMEDI_CMD ioctl. */
static int compat_cmd(struct file *file, unsigned long arg)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi_cmd cmd;
	bool copy = false;
	int rc, err;

	rc = get_compat_cmd(&cmd, compat_ptr(arg));
	if (rc)
		return rc;

	mutex_lock(&dev->mutex);
	rc = do_cmd_ioctl(dev, &cmd, &copy, file);
	mutex_unlock(&dev->mutex);
	if (copy) {
		/* Special case: copy cmd back to user. */
		err = put_compat_cmd(compat_ptr(arg), &cmd);
		if (err)
			rc = err;
	}
	return rc;
}

/* Handle 32-bit COMEDI_CMDTEST ioctl. */
static int compat_cmdtest(struct file *file, unsigned long arg)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi_cmd cmd;
	bool copy = false;
	int rc, err;

	rc = get_compat_cmd(&cmd, compat_ptr(arg));
	if (rc)
		return rc;

	mutex_lock(&dev->mutex);
	rc = do_cmdtest_ioctl(dev, &cmd, &copy, file);
	mutex_unlock(&dev->mutex);
	if (copy) {
		err = put_compat_cmd(compat_ptr(arg), &cmd);
		if (err)
			rc = err;
	}
	return rc;
}

/* Copy 32-bit insn structure to native insn structure. */
static int get_compat_insn(struct comedi_insn *insn,
			   struct comedi32_insn_struct __user *insn32)
{
	struct comedi32_insn_struct v32;

	/* Copy insn structure.  Ignore the unused members. */
	if (copy_from_user(&v32, insn32, sizeof(v32)))
		return -EFAULT;
	memset(insn, 0, sizeof(*insn));
	insn->insn = v32.insn;
	insn->n = v32.n;
	insn->data = compat_ptr(v32.data);
	insn->subdev = v32.subdev;
	insn->chanspec = v32.chanspec;
	return 0;
}

/* Handle 32-bit COMEDI_INSNLIST ioctl. */
static int compat_insnlist(struct file *file, unsigned long arg)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi32_insnlist_struct insnlist32;
	struct comedi32_insn_struct __user *insn32;
	struct comedi_insn *insns;
	unsigned int n;
	int rc;

	if (copy_from_user(&insnlist32, compat_ptr(arg), sizeof(insnlist32)))
		return -EFAULT;

	insns = kcalloc(insnlist32.n_insns, sizeof(*insns), GFP_KERNEL);
	if (!insns)
		return -ENOMEM;

	/* Copy insn structures. */
	insn32 = compat_ptr(insnlist32.insns);
	for (n = 0; n < insnlist32.n_insns; n++) {
		rc = get_compat_insn(insns + n, insn32 + n);
		if (rc) {
			kfree(insns);
			return rc;
		}
	}

	mutex_lock(&dev->mutex);
	rc = do_insnlist_ioctl(dev, insns, insnlist32.n_insns, file);
	mutex_unlock(&dev->mutex);
	kfree(insns);
	return rc;
}

/* Handle 32-bit COMEDI_INSN ioctl. */
static int compat_insn(struct file *file, unsigned long arg)
{
	struct comedi_file *cfp = file->private_data;
	struct comedi_device *dev = cfp->dev;
	struct comedi_insn insn;
	int rc;

	rc = get_compat_insn(&insn, (void __user *)arg);
	if (rc)
		return rc;

	mutex_lock(&dev->mutex);
	rc = do_insn_ioctl(dev, &insn, file);
	mutex_unlock(&dev->mutex);
	return rc;
}

/*
 * compat_ioctl file operation.
 *
 * Returns -ENOIOCTLCMD for unrecognised ioctl codes.
 */
static long comedi_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	int rc;

	switch (cmd) {
	case COMEDI_DEVCONFIG:
	case COMEDI_DEVINFO:
	case COMEDI_SUBDINFO:
	case COMEDI_BUFCONFIG:
	case COMEDI_BUFINFO:
		/* Just need to translate the pointer argument. */
		arg = (unsigned long)compat_ptr(arg);
		rc = comedi_unlocked_ioctl(file, cmd, arg);
		break;
	case COMEDI_LOCK:
	case COMEDI_UNLOCK:
	case COMEDI_CANCEL:
	case COMEDI_POLL:
	case COMEDI_SETRSUBD:
	case COMEDI_SETWSUBD:
		/* No translation needed. */
		rc = comedi_unlocked_ioctl(file, cmd, arg);
		break;
	case COMEDI32_CHANINFO:
		rc = compat_chaninfo(file, arg);
		break;
	case COMEDI32_RANGEINFO:
		rc = compat_rangeinfo(file, arg);
		break;
	case COMEDI32_CMD:
		rc = compat_cmd(file, arg);
		break;
	case COMEDI32_CMDTEST:
		rc = compat_cmdtest(file, arg);
		break;
	case COMEDI32_INSNLIST:
		rc = compat_insnlist(file, arg);
		break;
	case COMEDI32_INSN:
		rc = compat_insn(file, arg);
		break;
	default:
		rc = -ENOIOCTLCMD;
		break;
	}
	return rc;
}
#else
#define comedi_compat_ioctl NULL
#endif

static const struct file_operations comedi_fops = {
	.owner = THIS_MODULE,
	.unlocked_ioctl = comedi_unlocked_ioctl,
	.compat_ioctl = comedi_compat_ioctl,
	.open = comedi_open,
	.release = comedi_close,
	.read = comedi_read,
	.write = comedi_write,
	.mmap = comedi_mmap,
	.poll = comedi_poll,
	.fasync = comedi_fasync,
	.llseek = noop_llseek,
};

/**
 * comedi_event() - Handle events for asynchronous COMEDI command
 * @dev: COMEDI device.
 * @s: COMEDI subdevice.
 * Context: in_interrupt() (usually), @s->spin_lock spin-lock not held.
 *
 * If an asynchronous COMEDI command is active on the subdevice, process
 * any %COMEDI_CB_... event flags that have been set, usually by an
 * interrupt handler.  These may change the run state of the asynchronous
 * command, wake a task, and/or send a %SIGIO signal.
 */
void comedi_event(struct comedi_device *dev, struct comedi_subdevice *s)
{
	struct comedi_async *async = s->async;
	unsigned int events;
	int si_code = 0;
	unsigned long flags;

	spin_lock_irqsave(&s->spin_lock, flags);

	events = async->events;
	async->events = 0;
	if (!__comedi_is_subdevice_running(s)) {
		spin_unlock_irqrestore(&s->spin_lock, flags);
		return;
	}

	if (events & COMEDI_CB_CANCEL_MASK)
		__comedi_clear_subdevice_runflags(s, COMEDI_SRF_RUNNING);

	/*
	 * Remember if an error event has occurred, so an error can be
	 * returned the next time the user does a read() or write().
	 */
	if (events & COMEDI_CB_ERROR_MASK)
		__comedi_set_subdevice_runflags(s, COMEDI_SRF_ERROR);

	if (async->cb_mask & events) {
		wake_up_interruptible(&async->wait_head);
		si_code = async->cmd.flags & CMDF_WRITE ? POLL_OUT : POLL_IN;
	}

	spin_unlock_irqrestore(&s->spin_lock, flags);

	if (si_code)
		kill_fasync(&dev->async_queue, SIGIO, si_code);
}
EXPORT_SYMBOL_GPL(comedi_event);

/* Note: the ->mutex is pre-locked on successful return */
struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device)
{
	struct comedi_device *dev;
	struct device *csdev;
	unsigned int i;

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		return ERR_PTR(-ENOMEM);
	comedi_device_init(dev);
	comedi_set_hw_dev(dev, hardware_device);
	mutex_lock(&dev->mutex);
	mutex_lock(&comedi_board_minor_table_lock);
	for (i = hardware_device ? comedi_num_legacy_minors : 0;
	     i < COMEDI_NUM_BOARD_MINORS; ++i) {
		if (!comedi_board_minor_table[i]) {
			comedi_board_minor_table[i] = dev;
			break;
		}
	}
	mutex_unlock(&comedi_board_minor_table_lock);
	if (i == COMEDI_NUM_BOARD_MINORS) {
		mutex_unlock(&dev->mutex);
		comedi_device_cleanup(dev);
		comedi_dev_put(dev);
		dev_err(hardware_device,
			"ran out of minor numbers for board device files\n");
		return ERR_PTR(-EBUSY);
	}
	dev->minor = i;
	csdev = device_create(&comedi_class, hardware_device,
			      MKDEV(COMEDI_MAJOR, i), NULL, "comedi%i", i);
	if (!IS_ERR(csdev))
		dev->class_dev = get_device(csdev);

	/* Note: dev->mutex needs to be unlocked by the caller. */
	return dev;
}

void comedi_release_hardware_device(struct device *hardware_device)
{
	int minor;
	struct comedi_device *dev;

	for (minor = comedi_num_legacy_minors; minor < COMEDI_NUM_BOARD_MINORS;
	     minor++) {
		mutex_lock(&comedi_board_minor_table_lock);
		dev = comedi_board_minor_table[minor];
		if (dev && dev->hw_dev == hardware_device) {
			comedi_board_minor_table[minor] = NULL;
			mutex_unlock(&comedi_board_minor_table_lock);
			comedi_free_board_dev(dev);
			break;
		}
		mutex_unlock(&comedi_board_minor_table_lock);
	}
}

int comedi_alloc_subdevice_minor(struct comedi_subdevice *s)
{
	struct comedi_device *dev = s->device;
	struct device *csdev;
	unsigned int i;

	mutex_lock(&comedi_subdevice_minor_table_lock);
	for (i = 0; i < COMEDI_NUM_SUBDEVICE_MINORS; ++i) {
		if (!comedi_subdevice_minor_table[i]) {
			comedi_subdevice_minor_table[i] = s;
			break;
		}
	}
	mutex_unlock(&comedi_subdevice_minor_table_lock);
	if (i == COMEDI_NUM_SUBDEVICE_MINORS) {
		dev_err(dev->class_dev,
			"ran out of minor numbers for subdevice files\n");
		return -EBUSY;
	}
	i += COMEDI_NUM_BOARD_MINORS;
	s->minor = i;
	csdev = device_create(&comedi_class, dev->class_dev,
			      MKDEV(COMEDI_MAJOR, i), NULL, "comedi%i_subd%i",
			      dev->minor, s->index);
	if (!IS_ERR(csdev))
		s->class_dev = csdev;

	return 0;
}

void comedi_free_subdevice_minor(struct comedi_subdevice *s)
{
	unsigned int i;

	if (!s)
		return;
	if (s->minor < COMEDI_NUM_BOARD_MINORS ||
	    s->minor >= COMEDI_NUM_MINORS)
		return;

	i = s->minor - COMEDI_NUM_BOARD_MINORS;
	mutex_lock(&comedi_subdevice_minor_table_lock);
	if (s == comedi_subdevice_minor_table[i])
		comedi_subdevice_minor_table[i] = NULL;
	mutex_unlock(&comedi_subdevice_minor_table_lock);
	if (s->class_dev) {
		device_destroy(&comedi_class, MKDEV(COMEDI_MAJOR, s->minor));
		s->class_dev = NULL;
	}
}

static void comedi_cleanup_board_minors(void)
{
	struct comedi_device *dev;
	unsigned int i;

	for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
		dev = comedi_clear_board_minor(i);
		comedi_free_board_dev(dev);
	}
}

static int __init comedi_init(void)
{
	int i;
	int retval;

	pr_info("version " COMEDI_RELEASE " - http://www.comedi.org\n");

	if (comedi_num_legacy_minors > COMEDI_NUM_BOARD_MINORS) {
		pr_err("invalid value for module parameter \"comedi_num_legacy_minors\".  Valid values are 0 through %i.\n",
		       COMEDI_NUM_BOARD_MINORS);
		return -EINVAL;
	}

	retval = register_chrdev_region(MKDEV(COMEDI_MAJOR, 0),
					COMEDI_NUM_MINORS, "comedi");
	if (retval)
		return retval;

	cdev_init(&comedi_cdev, &comedi_fops);
	comedi_cdev.owner = THIS_MODULE;

	retval = kobject_set_name(&comedi_cdev.kobj, "comedi");
	if (retval)
		goto out_unregister_chrdev_region;

	retval = cdev_add(&comedi_cdev, MKDEV(COMEDI_MAJOR, 0),
			  COMEDI_NUM_MINORS);
	if (retval)
		goto out_unregister_chrdev_region;

	retval = class_register(&comedi_class);
	if (retval) {
		pr_err("failed to create class\n");
		goto out_cdev_del;
	}

	/* create devices files for legacy/manual use */
	for (i = 0; i < comedi_num_legacy_minors; i++) {
		struct comedi_device *dev;

		dev = comedi_alloc_board_minor(NULL);
		if (IS_ERR(dev)) {
			retval = PTR_ERR(dev);
			goto out_cleanup_board_minors;
		}
		/* comedi_alloc_board_minor() locked the mutex */
		lockdep_assert_held(&dev->mutex);
		mutex_unlock(&dev->mutex);
	}

	/* XXX requires /proc interface */
	comedi_proc_init();

	return 0;

out_cleanup_board_minors:
	comedi_cleanup_board_minors();
	class_unregister(&comedi_class);
out_cdev_del:
	cdev_del(&comedi_cdev);
out_unregister_chrdev_region:
	unregister_chrdev_region(MKDEV(COMEDI_MAJOR, 0), COMEDI_NUM_MINORS);
	return retval;
}
module_init(comedi_init);

static void __exit comedi_cleanup(void)
{
	comedi_cleanup_board_minors();
	class_unregister(&comedi_class);
	cdev_del(&comedi_cdev);
	unregister_chrdev_region(MKDEV(COMEDI_MAJOR, 0), COMEDI_NUM_MINORS);

	comedi_proc_cleanup();
}
module_exit(comedi_cleanup);

MODULE_AUTHOR("https://www.comedi.org");
MODULE_DESCRIPTION("Comedi core module");
MODULE_LICENSE("GPL");