summaryrefslogtreecommitdiff
path: root/drivers/tty/serial/serial_core.c
blob: 04c0bb18cfd3c02ec6ddae3fe3cb60250d54c44b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
// SPDX-License-Identifier: GPL-2.0+
/*
 *  Driver core for serial ports
 *
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 *  Copyright 1999 ARM Limited
 *  Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
 */
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/device.h>
#include <linux/serial.h> /* for serial_state and serial_icounter_struct */
#include <linux/serial_core.h>
#include <linux/sysrq.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/math64.h>
#include <linux/security.h>

#include <linux/irq.h>
#include <linux/uaccess.h>

/*
 * This is used to lock changes in serial line configuration.
 */
static DEFINE_MUTEX(port_mutex);

/*
 * lockdep: port->lock is initialized in two places, but we
 *          want only one lock-class:
 */
static struct lock_class_key port_lock_key;

#define HIGH_BITS_OFFSET	((sizeof(long)-sizeof(int))*8)

/*
 * Max time with active RTS before/after data is sent.
 */
#define RS485_MAX_RTS_DELAY	100 /* msecs */

static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
					struct ktermios *old_termios);
static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
static void uart_change_pm(struct uart_state *state,
			   enum uart_pm_state pm_state);

static void uart_port_shutdown(struct tty_port *port);

static int uart_dcd_enabled(struct uart_port *uport)
{
	return !!(uport->status & UPSTAT_DCD_ENABLE);
}

static inline struct uart_port *uart_port_ref(struct uart_state *state)
{
	if (atomic_add_unless(&state->refcount, 1, 0))
		return state->uart_port;
	return NULL;
}

static inline void uart_port_deref(struct uart_port *uport)
{
	if (atomic_dec_and_test(&uport->state->refcount))
		wake_up(&uport->state->remove_wait);
}

#define uart_port_lock(state, flags)					\
	({								\
		struct uart_port *__uport = uart_port_ref(state);	\
		if (__uport)						\
			spin_lock_irqsave(&__uport->lock, flags);	\
		__uport;						\
	})

#define uart_port_unlock(uport, flags)					\
	({								\
		struct uart_port *__uport = uport;			\
		if (__uport) {						\
			spin_unlock_irqrestore(&__uport->lock, flags);	\
			uart_port_deref(__uport);			\
		}							\
	})

static inline struct uart_port *uart_port_check(struct uart_state *state)
{
	lockdep_assert_held(&state->port.mutex);
	return state->uart_port;
}

/**
 * uart_write_wakeup - schedule write processing
 * @port: port to be processed
 *
 * This routine is used by the interrupt handler to schedule processing in the
 * software interrupt portion of the driver. A driver is expected to call this
 * function when the number of characters in the transmit buffer have dropped
 * below a threshold.
 *
 * Locking: @port->lock should be held
 */
void uart_write_wakeup(struct uart_port *port)
{
	struct uart_state *state = port->state;
	/*
	 * This means you called this function _after_ the port was
	 * closed.  No cookie for you.
	 */
	BUG_ON(!state);
	tty_port_tty_wakeup(&state->port);
}
EXPORT_SYMBOL(uart_write_wakeup);

static void uart_stop(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	unsigned long flags;

	port = uart_port_lock(state, flags);
	if (port)
		port->ops->stop_tx(port);
	uart_port_unlock(port, flags);
}

static void __uart_start(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port = state->uart_port;

	if (port && !uart_tx_stopped(port))
		port->ops->start_tx(port);
}

static void uart_start(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	unsigned long flags;

	port = uart_port_lock(state, flags);
	__uart_start(tty);
	uart_port_unlock(port, flags);
}

static void
uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
{
	unsigned long flags;
	unsigned int old;

	if (port->rs485.flags & SER_RS485_ENABLED) {
		set &= ~TIOCM_RTS;
		clear &= ~TIOCM_RTS;
	}

	spin_lock_irqsave(&port->lock, flags);
	old = port->mctrl;
	port->mctrl = (old & ~clear) | set;
	if (old != port->mctrl)
		port->ops->set_mctrl(port, port->mctrl);
	spin_unlock_irqrestore(&port->lock, flags);
}

#define uart_set_mctrl(port, set)	uart_update_mctrl(port, set, 0)
#define uart_clear_mctrl(port, clear)	uart_update_mctrl(port, 0, clear)

static void uart_port_dtr_rts(struct uart_port *uport, int raise)
{
	if (raise)
		uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
	else
		uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
}

/*
 * Startup the port.  This will be called once per open.  All calls
 * will be serialised by the per-port mutex.
 */
static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
		int init_hw)
{
	struct uart_port *uport = uart_port_check(state);
	unsigned long flags;
	unsigned long page;
	int retval = 0;

	if (uport->type == PORT_UNKNOWN)
		return 1;

	/*
	 * Make sure the device is in D0 state.
	 */
	uart_change_pm(state, UART_PM_STATE_ON);

	/*
	 * Initialise and allocate the transmit and temporary
	 * buffer.
	 */
	page = get_zeroed_page(GFP_KERNEL);
	if (!page)
		return -ENOMEM;

	uart_port_lock(state, flags);
	if (!state->xmit.buf) {
		state->xmit.buf = (unsigned char *) page;
		uart_circ_clear(&state->xmit);
		uart_port_unlock(uport, flags);
	} else {
		uart_port_unlock(uport, flags);
		/*
		 * Do not free() the page under the port lock, see
		 * uart_shutdown().
		 */
		free_page(page);
	}

	retval = uport->ops->startup(uport);
	if (retval == 0) {
		if (uart_console(uport) && uport->cons->cflag) {
			tty->termios.c_cflag = uport->cons->cflag;
			tty->termios.c_ispeed = uport->cons->ispeed;
			tty->termios.c_ospeed = uport->cons->ospeed;
			uport->cons->cflag = 0;
			uport->cons->ispeed = 0;
			uport->cons->ospeed = 0;
		}
		/*
		 * Initialise the hardware port settings.
		 */
		uart_change_speed(tty, state, NULL);

		/*
		 * Setup the RTS and DTR signals once the
		 * port is open and ready to respond.
		 */
		if (init_hw && C_BAUD(tty))
			uart_port_dtr_rts(uport, 1);
	}

	/*
	 * This is to allow setserial on this port. People may want to set
	 * port/irq/type and then reconfigure the port properly if it failed
	 * now.
	 */
	if (retval && capable(CAP_SYS_ADMIN))
		return 1;

	return retval;
}

static int uart_startup(struct tty_struct *tty, struct uart_state *state,
		int init_hw)
{
	struct tty_port *port = &state->port;
	int retval;

	if (tty_port_initialized(port))
		return 0;

	retval = uart_port_startup(tty, state, init_hw);
	if (retval)
		set_bit(TTY_IO_ERROR, &tty->flags);

	return retval;
}

/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.  Calls to
 * uart_shutdown are serialised by the per-port semaphore.
 *
 * uport == NULL if uart_port has already been removed
 */
static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
{
	struct uart_port *uport = uart_port_check(state);
	struct tty_port *port = &state->port;
	unsigned long flags;
	char *xmit_buf = NULL;

	/*
	 * Set the TTY IO error marker
	 */
	if (tty)
		set_bit(TTY_IO_ERROR, &tty->flags);

	if (tty_port_initialized(port)) {
		tty_port_set_initialized(port, 0);

		/*
		 * Turn off DTR and RTS early.
		 */
		if (uport && uart_console(uport) && tty) {
			uport->cons->cflag = tty->termios.c_cflag;
			uport->cons->ispeed = tty->termios.c_ispeed;
			uport->cons->ospeed = tty->termios.c_ospeed;
		}

		if (!tty || C_HUPCL(tty))
			uart_port_dtr_rts(uport, 0);

		uart_port_shutdown(port);
	}

	/*
	 * It's possible for shutdown to be called after suspend if we get
	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
	 * we don't try to resume a port that has been shutdown.
	 */
	tty_port_set_suspended(port, 0);

	/*
	 * Do not free() the transmit buffer page under the port lock since
	 * this can create various circular locking scenarios. For instance,
	 * console driver may need to allocate/free a debug object, which
	 * can endup in printk() recursion.
	 */
	uart_port_lock(state, flags);
	xmit_buf = state->xmit.buf;
	state->xmit.buf = NULL;
	uart_port_unlock(uport, flags);

	free_page((unsigned long)xmit_buf);
}

/**
 * uart_update_timeout - update per-port frame timing information
 * @port: uart_port structure describing the port
 * @cflag: termios cflag value
 * @baud: speed of the port
 *
 * Set the @port frame timing information from which the FIFO timeout value is
 * derived. The @cflag value should reflect the actual hardware settings as
 * number of bits, parity, stop bits and baud rate is taken into account here.
 *
 * Locking: caller is expected to take @port->lock
 */
void
uart_update_timeout(struct uart_port *port, unsigned int cflag,
		    unsigned int baud)
{
	unsigned int size = tty_get_frame_size(cflag);
	u64 frame_time;

	frame_time = (u64)size * NSEC_PER_SEC;
	port->frame_time = DIV64_U64_ROUND_UP(frame_time, baud);
}
EXPORT_SYMBOL(uart_update_timeout);

/**
 * uart_get_baud_rate - return baud rate for a particular port
 * @port: uart_port structure describing the port in question.
 * @termios: desired termios settings
 * @old: old termios (or %NULL)
 * @min: minimum acceptable baud rate
 * @max: maximum acceptable baud rate
 *
 * Decode the termios structure into a numeric baud rate, taking account of the
 * magic 38400 baud rate (with spd_* flags), and mapping the %B0 rate to 9600
 * baud.
 *
 * If the new baud rate is invalid, try the @old termios setting. If it's still
 * invalid, we try 9600 baud.
 *
 * The @termios structure is updated to reflect the baud rate we're actually
 * going to be using. Don't do this for the case where B0 is requested ("hang
 * up").
 *
 * Locking: caller dependent
 */
unsigned int
uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
		   const struct ktermios *old, unsigned int min, unsigned int max)
{
	unsigned int try;
	unsigned int baud;
	unsigned int altbaud;
	int hung_up = 0;
	upf_t flags = port->flags & UPF_SPD_MASK;

	switch (flags) {
	case UPF_SPD_HI:
		altbaud = 57600;
		break;
	case UPF_SPD_VHI:
		altbaud = 115200;
		break;
	case UPF_SPD_SHI:
		altbaud = 230400;
		break;
	case UPF_SPD_WARP:
		altbaud = 460800;
		break;
	default:
		altbaud = 38400;
		break;
	}

	for (try = 0; try < 2; try++) {
		baud = tty_termios_baud_rate(termios);

		/*
		 * The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
		 * Die! Die! Die!
		 */
		if (try == 0 && baud == 38400)
			baud = altbaud;

		/*
		 * Special case: B0 rate.
		 */
		if (baud == 0) {
			hung_up = 1;
			baud = 9600;
		}

		if (baud >= min && baud <= max)
			return baud;

		/*
		 * Oops, the quotient was zero.  Try again with
		 * the old baud rate if possible.
		 */
		termios->c_cflag &= ~CBAUD;
		if (old) {
			baud = tty_termios_baud_rate(old);
			if (!hung_up)
				tty_termios_encode_baud_rate(termios,
								baud, baud);
			old = NULL;
			continue;
		}

		/*
		 * As a last resort, if the range cannot be met then clip to
		 * the nearest chip supported rate.
		 */
		if (!hung_up) {
			if (baud <= min)
				tty_termios_encode_baud_rate(termios,
							min + 1, min + 1);
			else
				tty_termios_encode_baud_rate(termios,
							max - 1, max - 1);
		}
	}
	/* Should never happen */
	WARN_ON(1);
	return 0;
}
EXPORT_SYMBOL(uart_get_baud_rate);

/**
 * uart_get_divisor - return uart clock divisor
 * @port: uart_port structure describing the port
 * @baud: desired baud rate
 *
 * Calculate the divisor (baud_base / baud) for the specified @baud,
 * appropriately rounded.
 *
 * If 38400 baud and custom divisor is selected, return the custom divisor
 * instead.
 *
 * Locking: caller dependent
 */
unsigned int
uart_get_divisor(struct uart_port *port, unsigned int baud)
{
	unsigned int quot;

	/*
	 * Old custom speed handling.
	 */
	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
		quot = port->custom_divisor;
	else
		quot = DIV_ROUND_CLOSEST(port->uartclk, 16 * baud);

	return quot;
}
EXPORT_SYMBOL(uart_get_divisor);

/* Caller holds port mutex */
static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
					struct ktermios *old_termios)
{
	struct uart_port *uport = uart_port_check(state);
	struct ktermios *termios;
	int hw_stopped;

	/*
	 * If we have no tty, termios, or the port does not exist,
	 * then we can't set the parameters for this port.
	 */
	if (!tty || uport->type == PORT_UNKNOWN)
		return;

	termios = &tty->termios;
	uport->ops->set_termios(uport, termios, old_termios);

	/*
	 * Set modem status enables based on termios cflag
	 */
	spin_lock_irq(&uport->lock);
	if (termios->c_cflag & CRTSCTS)
		uport->status |= UPSTAT_CTS_ENABLE;
	else
		uport->status &= ~UPSTAT_CTS_ENABLE;

	if (termios->c_cflag & CLOCAL)
		uport->status &= ~UPSTAT_DCD_ENABLE;
	else
		uport->status |= UPSTAT_DCD_ENABLE;

	/* reset sw-assisted CTS flow control based on (possibly) new mode */
	hw_stopped = uport->hw_stopped;
	uport->hw_stopped = uart_softcts_mode(uport) &&
				!(uport->ops->get_mctrl(uport) & TIOCM_CTS);
	if (uport->hw_stopped) {
		if (!hw_stopped)
			uport->ops->stop_tx(uport);
	} else {
		if (hw_stopped)
			__uart_start(tty);
	}
	spin_unlock_irq(&uport->lock);
}

static int uart_put_char(struct tty_struct *tty, unsigned char c)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	struct circ_buf *circ;
	unsigned long flags;
	int ret = 0;

	circ = &state->xmit;
	port = uart_port_lock(state, flags);
	if (!circ->buf) {
		uart_port_unlock(port, flags);
		return 0;
	}

	if (port && uart_circ_chars_free(circ) != 0) {
		circ->buf[circ->head] = c;
		circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
		ret = 1;
	}
	uart_port_unlock(port, flags);
	return ret;
}

static void uart_flush_chars(struct tty_struct *tty)
{
	uart_start(tty);
}

static int uart_write(struct tty_struct *tty,
					const unsigned char *buf, int count)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	struct circ_buf *circ;
	unsigned long flags;
	int c, ret = 0;

	/*
	 * This means you called this function _after_ the port was
	 * closed.  No cookie for you.
	 */
	if (!state) {
		WARN_ON(1);
		return -EL3HLT;
	}

	port = uart_port_lock(state, flags);
	circ = &state->xmit;
	if (!circ->buf) {
		uart_port_unlock(port, flags);
		return 0;
	}

	while (port) {
		c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
		if (count < c)
			c = count;
		if (c <= 0)
			break;
		memcpy(circ->buf + circ->head, buf, c);
		circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
		buf += c;
		count -= c;
		ret += c;
	}

	__uart_start(tty);
	uart_port_unlock(port, flags);
	return ret;
}

static unsigned int uart_write_room(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	unsigned long flags;
	unsigned int ret;

	port = uart_port_lock(state, flags);
	ret = uart_circ_chars_free(&state->xmit);
	uart_port_unlock(port, flags);
	return ret;
}

static unsigned int uart_chars_in_buffer(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	unsigned long flags;
	unsigned int ret;

	port = uart_port_lock(state, flags);
	ret = uart_circ_chars_pending(&state->xmit);
	uart_port_unlock(port, flags);
	return ret;
}

static void uart_flush_buffer(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	unsigned long flags;

	/*
	 * This means you called this function _after_ the port was
	 * closed.  No cookie for you.
	 */
	if (!state) {
		WARN_ON(1);
		return;
	}

	pr_debug("uart_flush_buffer(%d) called\n", tty->index);

	port = uart_port_lock(state, flags);
	if (!port)
		return;
	uart_circ_clear(&state->xmit);
	if (port->ops->flush_buffer)
		port->ops->flush_buffer(port);
	uart_port_unlock(port, flags);
	tty_port_tty_wakeup(&state->port);
}

/*
 * This function performs low-level write of high-priority XON/XOFF
 * character and accounting for it.
 *
 * Requires uart_port to implement .serial_out().
 */
void uart_xchar_out(struct uart_port *uport, int offset)
{
	serial_port_out(uport, offset, uport->x_char);
	uport->icount.tx++;
	uport->x_char = 0;
}
EXPORT_SYMBOL_GPL(uart_xchar_out);

/*
 * This function is used to send a high-priority XON/XOFF character to
 * the device
 */
static void uart_send_xchar(struct tty_struct *tty, char ch)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	unsigned long flags;

	port = uart_port_ref(state);
	if (!port)
		return;

	if (port->ops->send_xchar)
		port->ops->send_xchar(port, ch);
	else {
		spin_lock_irqsave(&port->lock, flags);
		port->x_char = ch;
		if (ch)
			port->ops->start_tx(port);
		spin_unlock_irqrestore(&port->lock, flags);
	}
	uart_port_deref(port);
}

static void uart_throttle(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	upstat_t mask = UPSTAT_SYNC_FIFO;
	struct uart_port *port;

	port = uart_port_ref(state);
	if (!port)
		return;

	if (I_IXOFF(tty))
		mask |= UPSTAT_AUTOXOFF;
	if (C_CRTSCTS(tty))
		mask |= UPSTAT_AUTORTS;

	if (port->status & mask) {
		port->ops->throttle(port);
		mask &= ~port->status;
	}

	if (mask & UPSTAT_AUTORTS)
		uart_clear_mctrl(port, TIOCM_RTS);

	if (mask & UPSTAT_AUTOXOFF)
		uart_send_xchar(tty, STOP_CHAR(tty));

	uart_port_deref(port);
}

static void uart_unthrottle(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	upstat_t mask = UPSTAT_SYNC_FIFO;
	struct uart_port *port;

	port = uart_port_ref(state);
	if (!port)
		return;

	if (I_IXOFF(tty))
		mask |= UPSTAT_AUTOXOFF;
	if (C_CRTSCTS(tty))
		mask |= UPSTAT_AUTORTS;

	if (port->status & mask) {
		port->ops->unthrottle(port);
		mask &= ~port->status;
	}

	if (mask & UPSTAT_AUTORTS)
		uart_set_mctrl(port, TIOCM_RTS);

	if (mask & UPSTAT_AUTOXOFF)
		uart_send_xchar(tty, START_CHAR(tty));

	uart_port_deref(port);
}

static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
{
	struct uart_state *state = container_of(port, struct uart_state, port);
	struct uart_port *uport;
	int ret = -ENODEV;

	/*
	 * Ensure the state we copy is consistent and no hardware changes
	 * occur as we go
	 */
	mutex_lock(&port->mutex);
	uport = uart_port_check(state);
	if (!uport)
		goto out;

	retinfo->type	    = uport->type;
	retinfo->line	    = uport->line;
	retinfo->port	    = uport->iobase;
	if (HIGH_BITS_OFFSET)
		retinfo->port_high = (long) uport->iobase >> HIGH_BITS_OFFSET;
	retinfo->irq		    = uport->irq;
	retinfo->flags	    = (__force int)uport->flags;
	retinfo->xmit_fifo_size  = uport->fifosize;
	retinfo->baud_base	    = uport->uartclk / 16;
	retinfo->close_delay	    = jiffies_to_msecs(port->close_delay) / 10;
	retinfo->closing_wait    = port->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
				ASYNC_CLOSING_WAIT_NONE :
				jiffies_to_msecs(port->closing_wait) / 10;
	retinfo->custom_divisor  = uport->custom_divisor;
	retinfo->hub6	    = uport->hub6;
	retinfo->io_type         = uport->iotype;
	retinfo->iomem_reg_shift = uport->regshift;
	retinfo->iomem_base      = (void *)(unsigned long)uport->mapbase;

	ret = 0;
out:
	mutex_unlock(&port->mutex);
	return ret;
}

static int uart_get_info_user(struct tty_struct *tty,
			 struct serial_struct *ss)
{
	struct uart_state *state = tty->driver_data;
	struct tty_port *port = &state->port;

	return uart_get_info(port, ss) < 0 ? -EIO : 0;
}

static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
			 struct uart_state *state,
			 struct serial_struct *new_info)
{
	struct uart_port *uport = uart_port_check(state);
	unsigned long new_port;
	unsigned int change_irq, change_port, closing_wait;
	unsigned int old_custom_divisor, close_delay;
	upf_t old_flags, new_flags;
	int retval = 0;

	if (!uport)
		return -EIO;

	new_port = new_info->port;
	if (HIGH_BITS_OFFSET)
		new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;

	new_info->irq = irq_canonicalize(new_info->irq);
	close_delay = msecs_to_jiffies(new_info->close_delay * 10);
	closing_wait = new_info->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
			ASYNC_CLOSING_WAIT_NONE :
			msecs_to_jiffies(new_info->closing_wait * 10);


	change_irq  = !(uport->flags & UPF_FIXED_PORT)
		&& new_info->irq != uport->irq;

	/*
	 * Since changing the 'type' of the port changes its resource
	 * allocations, we should treat type changes the same as
	 * IO port changes.
	 */
	change_port = !(uport->flags & UPF_FIXED_PORT)
		&& (new_port != uport->iobase ||
		    (unsigned long)new_info->iomem_base != uport->mapbase ||
		    new_info->hub6 != uport->hub6 ||
		    new_info->io_type != uport->iotype ||
		    new_info->iomem_reg_shift != uport->regshift ||
		    new_info->type != uport->type);

	old_flags = uport->flags;
	new_flags = (__force upf_t)new_info->flags;
	old_custom_divisor = uport->custom_divisor;

	if (!capable(CAP_SYS_ADMIN)) {
		retval = -EPERM;
		if (change_irq || change_port ||
		    (new_info->baud_base != uport->uartclk / 16) ||
		    (close_delay != port->close_delay) ||
		    (closing_wait != port->closing_wait) ||
		    (new_info->xmit_fifo_size &&
		     new_info->xmit_fifo_size != uport->fifosize) ||
		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
			goto exit;
		uport->flags = ((uport->flags & ~UPF_USR_MASK) |
			       (new_flags & UPF_USR_MASK));
		uport->custom_divisor = new_info->custom_divisor;
		goto check_and_exit;
	}

	if (change_irq || change_port) {
		retval = security_locked_down(LOCKDOWN_TIOCSSERIAL);
		if (retval)
			goto exit;
	}

	/*
	 * Ask the low level driver to verify the settings.
	 */
	if (uport->ops->verify_port)
		retval = uport->ops->verify_port(uport, new_info);

	if ((new_info->irq >= nr_irqs) || (new_info->irq < 0) ||
	    (new_info->baud_base < 9600))
		retval = -EINVAL;

	if (retval)
		goto exit;

	if (change_port || change_irq) {
		retval = -EBUSY;

		/*
		 * Make sure that we are the sole user of this port.
		 */
		if (tty_port_users(port) > 1)
			goto exit;

		/*
		 * We need to shutdown the serial port at the old
		 * port/type/irq combination.
		 */
		uart_shutdown(tty, state);
	}

	if (change_port) {
		unsigned long old_iobase, old_mapbase;
		unsigned int old_type, old_iotype, old_hub6, old_shift;

		old_iobase = uport->iobase;
		old_mapbase = uport->mapbase;
		old_type = uport->type;
		old_hub6 = uport->hub6;
		old_iotype = uport->iotype;
		old_shift = uport->regshift;

		/*
		 * Free and release old regions
		 */
		if (old_type != PORT_UNKNOWN && uport->ops->release_port)
			uport->ops->release_port(uport);

		uport->iobase = new_port;
		uport->type = new_info->type;
		uport->hub6 = new_info->hub6;
		uport->iotype = new_info->io_type;
		uport->regshift = new_info->iomem_reg_shift;
		uport->mapbase = (unsigned long)new_info->iomem_base;

		/*
		 * Claim and map the new regions
		 */
		if (uport->type != PORT_UNKNOWN && uport->ops->request_port) {
			retval = uport->ops->request_port(uport);
		} else {
			/* Always success - Jean II */
			retval = 0;
		}

		/*
		 * If we fail to request resources for the
		 * new port, try to restore the old settings.
		 */
		if (retval) {
			uport->iobase = old_iobase;
			uport->type = old_type;
			uport->hub6 = old_hub6;
			uport->iotype = old_iotype;
			uport->regshift = old_shift;
			uport->mapbase = old_mapbase;

			if (old_type != PORT_UNKNOWN) {
				retval = uport->ops->request_port(uport);
				/*
				 * If we failed to restore the old settings,
				 * we fail like this.
				 */
				if (retval)
					uport->type = PORT_UNKNOWN;

				/*
				 * We failed anyway.
				 */
				retval = -EBUSY;
			}

			/* Added to return the correct error -Ram Gupta */
			goto exit;
		}
	}

	if (change_irq)
		uport->irq      = new_info->irq;
	if (!(uport->flags & UPF_FIXED_PORT))
		uport->uartclk  = new_info->baud_base * 16;
	uport->flags            = (uport->flags & ~UPF_CHANGE_MASK) |
				 (new_flags & UPF_CHANGE_MASK);
	uport->custom_divisor   = new_info->custom_divisor;
	port->close_delay     = close_delay;
	port->closing_wait    = closing_wait;
	if (new_info->xmit_fifo_size)
		uport->fifosize = new_info->xmit_fifo_size;

 check_and_exit:
	retval = 0;
	if (uport->type == PORT_UNKNOWN)
		goto exit;
	if (tty_port_initialized(port)) {
		if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||
		    old_custom_divisor != uport->custom_divisor) {
			/*
			 * If they're setting up a custom divisor or speed,
			 * instead of clearing it, then bitch about it.
			 */
			if (uport->flags & UPF_SPD_MASK) {
				dev_notice_ratelimited(uport->dev,
				       "%s sets custom speed on %s. This is deprecated.\n",
				      current->comm,
				      tty_name(port->tty));
			}
			uart_change_speed(tty, state, NULL);
		}
	} else {
		retval = uart_startup(tty, state, 1);
		if (retval == 0)
			tty_port_set_initialized(port, true);
		if (retval > 0)
			retval = 0;
	}
 exit:
	return retval;
}

static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
{
	struct uart_state *state = tty->driver_data;
	struct tty_port *port = &state->port;
	int retval;

	down_write(&tty->termios_rwsem);
	/*
	 * This semaphore protects port->count.  It is also
	 * very useful to prevent opens.  Also, take the
	 * port configuration semaphore to make sure that a
	 * module insertion/removal doesn't change anything
	 * under us.
	 */
	mutex_lock(&port->mutex);
	retval = uart_set_info(tty, port, state, ss);
	mutex_unlock(&port->mutex);
	up_write(&tty->termios_rwsem);
	return retval;
}

/**
 * uart_get_lsr_info - get line status register info
 * @tty: tty associated with the UART
 * @state: UART being queried
 * @value: returned modem value
 */
static int uart_get_lsr_info(struct tty_struct *tty,
			struct uart_state *state, unsigned int __user *value)
{
	struct uart_port *uport = uart_port_check(state);
	unsigned int result;

	result = uport->ops->tx_empty(uport);

	/*
	 * If we're about to load something into the transmit
	 * register, we'll pretend the transmitter isn't empty to
	 * avoid a race condition (depending on when the transmit
	 * interrupt happens).
	 */
	if (uport->x_char ||
	    ((uart_circ_chars_pending(&state->xmit) > 0) &&
	     !uart_tx_stopped(uport)))
		result &= ~TIOCSER_TEMT;

	return put_user(result, value);
}

static int uart_tiocmget(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct tty_port *port = &state->port;
	struct uart_port *uport;
	int result = -EIO;

	mutex_lock(&port->mutex);
	uport = uart_port_check(state);
	if (!uport)
		goto out;

	if (!tty_io_error(tty)) {
		result = uport->mctrl;
		spin_lock_irq(&uport->lock);
		result |= uport->ops->get_mctrl(uport);
		spin_unlock_irq(&uport->lock);
	}
out:
	mutex_unlock(&port->mutex);
	return result;
}

static int
uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
{
	struct uart_state *state = tty->driver_data;
	struct tty_port *port = &state->port;
	struct uart_port *uport;
	int ret = -EIO;

	mutex_lock(&port->mutex);
	uport = uart_port_check(state);
	if (!uport)
		goto out;

	if (!tty_io_error(tty)) {
		uart_update_mctrl(uport, set, clear);
		ret = 0;
	}
out:
	mutex_unlock(&port->mutex);
	return ret;
}

static int uart_break_ctl(struct tty_struct *tty, int break_state)
{
	struct uart_state *state = tty->driver_data;
	struct tty_port *port = &state->port;
	struct uart_port *uport;
	int ret = -EIO;

	mutex_lock(&port->mutex);
	uport = uart_port_check(state);
	if (!uport)
		goto out;

	if (uport->type != PORT_UNKNOWN && uport->ops->break_ctl)
		uport->ops->break_ctl(uport, break_state);
	ret = 0;
out:
	mutex_unlock(&port->mutex);
	return ret;
}

static int uart_do_autoconfig(struct tty_struct *tty, struct uart_state *state)
{
	struct tty_port *port = &state->port;
	struct uart_port *uport;
	int flags, ret;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	/*
	 * Take the per-port semaphore.  This prevents count from
	 * changing, and hence any extra opens of the port while
	 * we're auto-configuring.
	 */
	if (mutex_lock_interruptible(&port->mutex))
		return -ERESTARTSYS;

	uport = uart_port_check(state);
	if (!uport) {
		ret = -EIO;
		goto out;
	}

	ret = -EBUSY;
	if (tty_port_users(port) == 1) {
		uart_shutdown(tty, state);

		/*
		 * If we already have a port type configured,
		 * we must release its resources.
		 */
		if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
			uport->ops->release_port(uport);

		flags = UART_CONFIG_TYPE;
		if (uport->flags & UPF_AUTO_IRQ)
			flags |= UART_CONFIG_IRQ;

		/*
		 * This will claim the ports resources if
		 * a port is found.
		 */
		uport->ops->config_port(uport, flags);

		ret = uart_startup(tty, state, 1);
		if (ret == 0)
			tty_port_set_initialized(port, true);
		if (ret > 0)
			ret = 0;
	}
out:
	mutex_unlock(&port->mutex);
	return ret;
}

static void uart_enable_ms(struct uart_port *uport)
{
	/*
	 * Force modem status interrupts on
	 */
	if (uport->ops->enable_ms)
		uport->ops->enable_ms(uport);
}

/*
 * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
 * - mask passed in arg for lines of interest
 *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
 * Caller should use TIOCGICOUNT to see which one it was
 *
 * FIXME: This wants extracting into a common all driver implementation
 * of TIOCMWAIT using tty_port.
 */
static int uart_wait_modem_status(struct uart_state *state, unsigned long arg)
{
	struct uart_port *uport;
	struct tty_port *port = &state->port;
	DECLARE_WAITQUEUE(wait, current);
	struct uart_icount cprev, cnow;
	int ret;

	/*
	 * note the counters on entry
	 */
	uport = uart_port_ref(state);
	if (!uport)
		return -EIO;
	spin_lock_irq(&uport->lock);
	memcpy(&cprev, &uport->icount, sizeof(struct uart_icount));
	uart_enable_ms(uport);
	spin_unlock_irq(&uport->lock);

	add_wait_queue(&port->delta_msr_wait, &wait);
	for (;;) {
		spin_lock_irq(&uport->lock);
		memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
		spin_unlock_irq(&uport->lock);

		set_current_state(TASK_INTERRUPTIBLE);

		if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
		    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
		    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
		    ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
			ret = 0;
			break;
		}

		schedule();

		/* see if a signal did it */
		if (signal_pending(current)) {
			ret = -ERESTARTSYS;
			break;
		}

		cprev = cnow;
	}
	__set_current_state(TASK_RUNNING);
	remove_wait_queue(&port->delta_msr_wait, &wait);
	uart_port_deref(uport);

	return ret;
}

/*
 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
 * Return: write counters to the user passed counter struct
 * NB: both 1->0 and 0->1 transitions are counted except for
 *     RI where only 0->1 is counted.
 */
static int uart_get_icount(struct tty_struct *tty,
			  struct serial_icounter_struct *icount)
{
	struct uart_state *state = tty->driver_data;
	struct uart_icount cnow;
	struct uart_port *uport;

	uport = uart_port_ref(state);
	if (!uport)
		return -EIO;
	spin_lock_irq(&uport->lock);
	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
	spin_unlock_irq(&uport->lock);
	uart_port_deref(uport);

	icount->cts         = cnow.cts;
	icount->dsr         = cnow.dsr;
	icount->rng         = cnow.rng;
	icount->dcd         = cnow.dcd;
	icount->rx          = cnow.rx;
	icount->tx          = cnow.tx;
	icount->frame       = cnow.frame;
	icount->overrun     = cnow.overrun;
	icount->parity      = cnow.parity;
	icount->brk         = cnow.brk;
	icount->buf_overrun = cnow.buf_overrun;

	return 0;
}

#define SER_RS485_LEGACY_FLAGS	(SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \
				 SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \
				 SER_RS485_TERMINATE_BUS)

static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *rs485)
{
	u32 flags = rs485->flags;

	/* Don't return -EINVAL for unsupported legacy flags */
	flags &= ~SER_RS485_LEGACY_FLAGS;

	/*
	 * For any bit outside of the legacy ones that is not supported by
	 * the driver, return -EINVAL.
	 */
	if (flags & ~port->rs485_supported.flags)
		return -EINVAL;

	/* Asking for address w/o addressing mode? */
	if (!(rs485->flags & SER_RS485_ADDRB) &&
	    (rs485->flags & (SER_RS485_ADDR_RECV|SER_RS485_ADDR_DEST)))
		return -EINVAL;

	/* Address given but not enabled? */
	if (!(rs485->flags & SER_RS485_ADDR_RECV) && rs485->addr_recv)
		return -EINVAL;
	if (!(rs485->flags & SER_RS485_ADDR_DEST) && rs485->addr_dest)
		return -EINVAL;

	return 0;
}

static void uart_sanitize_serial_rs485_delays(struct uart_port *port,
					      struct serial_rs485 *rs485)
{
	if (!port->rs485_supported.delay_rts_before_send) {
		if (rs485->delay_rts_before_send) {
			dev_warn_ratelimited(port->dev,
				"%s (%d): RTS delay before sending not supported\n",
				port->name, port->line);
		}
		rs485->delay_rts_before_send = 0;
	} else if (rs485->delay_rts_before_send > RS485_MAX_RTS_DELAY) {
		rs485->delay_rts_before_send = RS485_MAX_RTS_DELAY;
		dev_warn_ratelimited(port->dev,
			"%s (%d): RTS delay before sending clamped to %u ms\n",
			port->name, port->line, rs485->delay_rts_before_send);
	}

	if (!port->rs485_supported.delay_rts_after_send) {
		if (rs485->delay_rts_after_send) {
			dev_warn_ratelimited(port->dev,
				"%s (%d): RTS delay after sending not supported\n",
				port->name, port->line);
		}
		rs485->delay_rts_after_send = 0;
	} else if (rs485->delay_rts_after_send > RS485_MAX_RTS_DELAY) {
		rs485->delay_rts_after_send = RS485_MAX_RTS_DELAY;
		dev_warn_ratelimited(port->dev,
			"%s (%d): RTS delay after sending clamped to %u ms\n",
			port->name, port->line, rs485->delay_rts_after_send);
	}
}

static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs485 *rs485)
{
	u32 supported_flags = port->rs485_supported.flags;

	if (!(rs485->flags & SER_RS485_ENABLED)) {
		memset(rs485, 0, sizeof(*rs485));
		return;
	}

	/* Pick sane settings if the user hasn't */
	if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
	    !(rs485->flags & SER_RS485_RTS_ON_SEND) ==
	    !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
		dev_warn_ratelimited(port->dev,
			"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
			port->name, port->line);
		rs485->flags |= SER_RS485_RTS_ON_SEND;
		rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
		supported_flags |= SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND;
	}

	rs485->flags &= supported_flags;

	uart_sanitize_serial_rs485_delays(port, rs485);

	/* Return clean padding area to userspace */
	memset(rs485->padding0, 0, sizeof(rs485->padding0));
	memset(rs485->padding1, 0, sizeof(rs485->padding1));
}

static void uart_set_rs485_termination(struct uart_port *port,
				       const struct serial_rs485 *rs485)
{
	if (!(rs485->flags & SER_RS485_ENABLED))
		return;

	gpiod_set_value_cansleep(port->rs485_term_gpio,
				 !!(rs485->flags & SER_RS485_TERMINATE_BUS));
}

int uart_rs485_config(struct uart_port *port)
{
	struct serial_rs485 *rs485 = &port->rs485;
	int ret;

	uart_sanitize_serial_rs485(port, rs485);
	uart_set_rs485_termination(port, rs485);

	ret = port->rs485_config(port, NULL, rs485);
	if (ret)
		memset(rs485, 0, sizeof(*rs485));

	return ret;
}
EXPORT_SYMBOL_GPL(uart_rs485_config);

static int uart_get_rs485_config(struct uart_port *port,
			 struct serial_rs485 __user *rs485)
{
	unsigned long flags;
	struct serial_rs485 aux;

	spin_lock_irqsave(&port->lock, flags);
	aux = port->rs485;
	spin_unlock_irqrestore(&port->lock, flags);

	if (copy_to_user(rs485, &aux, sizeof(aux)))
		return -EFAULT;

	return 0;
}

static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
			 struct serial_rs485 __user *rs485_user)
{
	struct serial_rs485 rs485;
	int ret;
	unsigned long flags;

	if (!port->rs485_config)
		return -ENOTTY;

	if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
		return -EFAULT;

	ret = uart_check_rs485_flags(port, &rs485);
	if (ret)
		return ret;
	uart_sanitize_serial_rs485(port, &rs485);
	uart_set_rs485_termination(port, &rs485);

	spin_lock_irqsave(&port->lock, flags);
	ret = port->rs485_config(port, &tty->termios, &rs485);
	if (!ret)
		port->rs485 = rs485;
	spin_unlock_irqrestore(&port->lock, flags);
	if (ret)
		return ret;

	if (copy_to_user(rs485_user, &port->rs485, sizeof(port->rs485)))
		return -EFAULT;

	return 0;
}

static int uart_get_iso7816_config(struct uart_port *port,
				   struct serial_iso7816 __user *iso7816)
{
	unsigned long flags;
	struct serial_iso7816 aux;

	if (!port->iso7816_config)
		return -ENOTTY;

	spin_lock_irqsave(&port->lock, flags);
	aux = port->iso7816;
	spin_unlock_irqrestore(&port->lock, flags);

	if (copy_to_user(iso7816, &aux, sizeof(aux)))
		return -EFAULT;

	return 0;
}

static int uart_set_iso7816_config(struct uart_port *port,
				   struct serial_iso7816 __user *iso7816_user)
{
	struct serial_iso7816 iso7816;
	int i, ret;
	unsigned long flags;

	if (!port->iso7816_config)
		return -ENOTTY;

	if (copy_from_user(&iso7816, iso7816_user, sizeof(*iso7816_user)))
		return -EFAULT;

	/*
	 * There are 5 words reserved for future use. Check that userspace
	 * doesn't put stuff in there to prevent breakages in the future.
	 */
	for (i = 0; i < 5; i++)
		if (iso7816.reserved[i])
			return -EINVAL;

	spin_lock_irqsave(&port->lock, flags);
	ret = port->iso7816_config(port, &iso7816);
	spin_unlock_irqrestore(&port->lock, flags);
	if (ret)
		return ret;

	if (copy_to_user(iso7816_user, &port->iso7816, sizeof(port->iso7816)))
		return -EFAULT;

	return 0;
}

/*
 * Called via sys_ioctl.  We can use spin_lock_irq() here.
 */
static int
uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
{
	struct uart_state *state = tty->driver_data;
	struct tty_port *port = &state->port;
	struct uart_port *uport;
	void __user *uarg = (void __user *)arg;
	int ret = -ENOIOCTLCMD;


	/*
	 * These ioctls don't rely on the hardware to be present.
	 */
	switch (cmd) {
	case TIOCSERCONFIG:
		down_write(&tty->termios_rwsem);
		ret = uart_do_autoconfig(tty, state);
		up_write(&tty->termios_rwsem);
		break;
	}

	if (ret != -ENOIOCTLCMD)
		goto out;

	if (tty_io_error(tty)) {
		ret = -EIO;
		goto out;
	}

	/*
	 * The following should only be used when hardware is present.
	 */
	switch (cmd) {
	case TIOCMIWAIT:
		ret = uart_wait_modem_status(state, arg);
		break;
	}

	if (ret != -ENOIOCTLCMD)
		goto out;

	/* rs485_config requires more locking than others */
	if (cmd == TIOCGRS485)
		down_write(&tty->termios_rwsem);

	mutex_lock(&port->mutex);
	uport = uart_port_check(state);

	if (!uport || tty_io_error(tty)) {
		ret = -EIO;
		goto out_up;
	}

	/*
	 * All these rely on hardware being present and need to be
	 * protected against the tty being hung up.
	 */

	switch (cmd) {
	case TIOCSERGETLSR: /* Get line status register */
		ret = uart_get_lsr_info(tty, state, uarg);
		break;

	case TIOCGRS485:
		ret = uart_get_rs485_config(uport, uarg);
		break;

	case TIOCSRS485:
		ret = uart_set_rs485_config(tty, uport, uarg);
		break;

	case TIOCSISO7816:
		ret = uart_set_iso7816_config(state->uart_port, uarg);
		break;

	case TIOCGISO7816:
		ret = uart_get_iso7816_config(state->uart_port, uarg);
		break;
	default:
		if (uport->ops->ioctl)
			ret = uport->ops->ioctl(uport, cmd, arg);
		break;
	}
out_up:
	mutex_unlock(&port->mutex);
	if (cmd == TIOCGRS485)
		up_write(&tty->termios_rwsem);
out:
	return ret;
}

static void uart_set_ldisc(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *uport;
	struct tty_port *port = &state->port;

	if (!tty_port_initialized(port))
		return;

	mutex_lock(&state->port.mutex);
	uport = uart_port_check(state);
	if (uport && uport->ops->set_ldisc)
		uport->ops->set_ldisc(uport, &tty->termios);
	mutex_unlock(&state->port.mutex);
}

static void uart_set_termios(struct tty_struct *tty,
						struct ktermios *old_termios)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *uport;
	unsigned int cflag = tty->termios.c_cflag;
	unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
	bool sw_changed = false;

	mutex_lock(&state->port.mutex);
	uport = uart_port_check(state);
	if (!uport)
		goto out;

	/*
	 * Drivers doing software flow control also need to know
	 * about changes to these input settings.
	 */
	if (uport->flags & UPF_SOFT_FLOW) {
		iflag_mask |= IXANY|IXON|IXOFF;
		sw_changed =
		   tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
		   tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
	}

	/*
	 * These are the bits that are used to setup various
	 * flags in the low level driver. We can ignore the Bfoo
	 * bits in c_cflag; c_[io]speed will always be set
	 * appropriately by set_termios() in tty_ioctl.c
	 */
	if ((cflag ^ old_termios->c_cflag) == 0 &&
	    tty->termios.c_ospeed == old_termios->c_ospeed &&
	    tty->termios.c_ispeed == old_termios->c_ispeed &&
	    ((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
	    !sw_changed) {
		goto out;
	}

	uart_change_speed(tty, state, old_termios);
	/* reload cflag from termios; port driver may have overridden flags */
	cflag = tty->termios.c_cflag;

	/* Handle transition to B0 status */
	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
		uart_clear_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
	/* Handle transition away from B0 status */
	else if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
		unsigned int mask = TIOCM_DTR;

		if (!(cflag & CRTSCTS) || !tty_throttled(tty))
			mask |= TIOCM_RTS;
		uart_set_mctrl(uport, mask);
	}
out:
	mutex_unlock(&state->port.mutex);
}

/*
 * Calls to uart_close() are serialised via the tty_lock in
 *   drivers/tty/tty_io.c:tty_release()
 *   drivers/tty/tty_io.c:do_tty_hangup()
 */
static void uart_close(struct tty_struct *tty, struct file *filp)
{
	struct uart_state *state = tty->driver_data;

	if (!state) {
		struct uart_driver *drv = tty->driver->driver_state;
		struct tty_port *port;

		state = drv->state + tty->index;
		port = &state->port;
		spin_lock_irq(&port->lock);
		--port->count;
		spin_unlock_irq(&port->lock);
		return;
	}

	pr_debug("uart_close(%d) called\n", tty->index);

	tty_port_close(tty->port, tty, filp);
}

static void uart_tty_port_shutdown(struct tty_port *port)
{
	struct uart_state *state = container_of(port, struct uart_state, port);
	struct uart_port *uport = uart_port_check(state);
	char *buf;

	/*
	 * At this point, we stop accepting input.  To do this, we
	 * disable the receive line status interrupts.
	 */
	if (WARN(!uport, "detached port still initialized!\n"))
		return;

	spin_lock_irq(&uport->lock);
	uport->ops->stop_rx(uport);
	spin_unlock_irq(&uport->lock);

	uart_port_shutdown(port);

	/*
	 * It's possible for shutdown to be called after suspend if we get
	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
	 * we don't try to resume a port that has been shutdown.
	 */
	tty_port_set_suspended(port, 0);

	/*
	 * Free the transmit buffer.
	 */
	spin_lock_irq(&uport->lock);
	buf = state->xmit.buf;
	state->xmit.buf = NULL;
	spin_unlock_irq(&uport->lock);

	free_page((unsigned long)buf);

	uart_change_pm(state, UART_PM_STATE_OFF);
}

static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
{
	struct uart_state *state = tty->driver_data;
	struct uart_port *port;
	unsigned long char_time, expire, fifo_timeout;

	port = uart_port_ref(state);
	if (!port)
		return;

	if (port->type == PORT_UNKNOWN || port->fifosize == 0) {
		uart_port_deref(port);
		return;
	}

	/*
	 * Set the check interval to be 1/5 of the estimated time to
	 * send a single character, and make it at least 1.  The check
	 * interval should also be less than the timeout.
	 *
	 * Note: we have to use pretty tight timings here to satisfy
	 * the NIST-PCTS.
	 */
	char_time = max(nsecs_to_jiffies(port->frame_time / 5), 1UL);

	if (timeout && timeout < char_time)
		char_time = timeout;

	if (!uart_cts_enabled(port)) {
		/*
		 * If the transmitter hasn't cleared in twice the approximate
		 * amount of time to send the entire FIFO, it probably won't
		 * ever clear.  This assumes the UART isn't doing flow
		 * control, which is currently the case.  Hence, if it ever
		 * takes longer than FIFO timeout, this is probably due to a
		 * UART bug of some kind.  So, we clamp the timeout parameter at
		 * 2 * FIFO timeout.
		 */
		fifo_timeout = uart_fifo_timeout(port);
		if (timeout == 0 || timeout > 2 * fifo_timeout)
			timeout = 2 * fifo_timeout;
	}

	expire = jiffies + timeout;

	pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n",
		port->line, jiffies, expire);

	/*
	 * Check whether the transmitter is empty every 'char_time'.
	 * 'timeout' / 'expire' give us the maximum amount of time
	 * we wait.
	 */
	while (!port->ops->tx_empty(port)) {
		msleep_interruptible(jiffies_to_msecs(char_time));
		if (signal_pending(current))
			break;
		if (timeout && time_after(jiffies, expire))
			break;
	}
	uart_port_deref(port);
}

/*
 * Calls to uart_hangup() are serialised by the tty_lock in
 *   drivers/tty/tty_io.c:do_tty_hangup()
 * This runs from a workqueue and can sleep for a _short_ time only.
 */
static void uart_hangup(struct tty_struct *tty)
{
	struct uart_state *state = tty->driver_data;
	struct tty_port *port = &state->port;
	struct uart_port *uport;
	unsigned long flags;

	pr_debug("uart_hangup(%d)\n", tty->index);

	mutex_lock(&port->mutex);
	uport = uart_port_check(state);
	WARN(!uport, "hangup of detached port!\n");

	if (tty_port_active(port)) {
		uart_flush_buffer(tty);
		uart_shutdown(tty, state);
		spin_lock_irqsave(&port->lock, flags);
		port->count = 0;
		spin_unlock_irqrestore(&port->lock, flags);
		tty_port_set_active(port, 0);
		tty_port_tty_set(port, NULL);
		if (uport && !uart_console(uport))
			uart_change_pm(state, UART_PM_STATE_OFF);
		wake_up_interruptible(&port->open_wait);
		wake_up_interruptible(&port->delta_msr_wait);
	}
	mutex_unlock(&port->mutex);
}

/* uport == NULL if uart_port has already been removed */
static void uart_port_shutdown(struct tty_port *port)
{
	struct uart_state *state = container_of(port, struct uart_state, port);
	struct uart_port *uport = uart_port_check(state);

	/*
	 * clear delta_msr_wait queue to avoid mem leaks: we may free
	 * the irq here so the queue might never be woken up.  Note
	 * that we won't end up waiting on delta_msr_wait again since
	 * any outstanding file descriptors should be pointing at
	 * hung_up_tty_fops now.
	 */
	wake_up_interruptible(&port->delta_msr_wait);

	if (uport) {
		/* Free the IRQ and disable the port. */
		uport->ops->shutdown(uport);

		/* Ensure that the IRQ handler isn't running on another CPU. */
		synchronize_irq(uport->irq);
	}
}

static int uart_carrier_raised(struct tty_port *port)
{
	struct uart_state *state = container_of(port, struct uart_state, port);
	struct uart_port *uport;
	int mctrl;

	uport = uart_port_ref(state);
	/*
	 * Should never observe uport == NULL since checks for hangup should
	 * abort the tty_port_block_til_ready() loop before checking for carrier
	 * raised -- but report carrier raised if it does anyway so open will
	 * continue and not sleep
	 */
	if (WARN_ON(!uport))
		return 1;
	spin_lock_irq(&uport->lock);
	uart_enable_ms(uport);
	mctrl = uport->ops->get_mctrl(uport);
	spin_unlock_irq(&uport->lock);
	uart_port_deref(uport);
	if (mctrl & TIOCM_CAR)
		return 1;
	return 0;
}

static void uart_dtr_rts(struct tty_port *port, int raise)
{
	struct uart_state *state = container_of(port, struct uart_state, port);
	struct uart_port *uport;

	uport = uart_port_ref(state);
	if (!uport)
		return;
	uart_port_dtr_rts(uport, raise);
	uart_port_deref(uport);
}

static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
{
	struct uart_driver *drv = driver->driver_state;
	struct uart_state *state = drv->state + tty->index;

	tty->driver_data = state;

	return tty_standard_install(driver, tty);
}

/*
 * Calls to uart_open are serialised by the tty_lock in
 *   drivers/tty/tty_io.c:tty_open()
 * Note that if this fails, then uart_close() _will_ be called.
 *
 * In time, we want to scrap the "opening nonpresent ports"
 * behaviour and implement an alternative way for setserial
 * to set base addresses/ports/types.  This will allow us to
 * get rid of a certain amount of extra tests.
 */
static int uart_open(struct tty_struct *tty, struct file *filp)
{
	struct uart_state *state = tty->driver_data;
	int retval;

	retval = tty_port_open(&state->port, tty, filp);
	if (retval > 0)
		retval = 0;

	return retval;
}

static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
{
	struct uart_state *state = container_of(port, struct uart_state, port);
	struct uart_port *uport;
	int ret;

	uport = uart_port_check(state);
	if (!uport || uport->flags & UPF_DEAD)
		return -ENXIO;

	/*
	 * Start up the serial port.
	 */
	ret = uart_startup(tty, state, 0);
	if (ret > 0)
		tty_port_set_active(port, 1);

	return ret;
}

static const char *uart_type(struct uart_port *port)
{
	const char *str = NULL;

	if (port->ops->type)
		str = port->ops->type(port);

	if (!str)
		str = "unknown";

	return str;
}

#ifdef CONFIG_PROC_FS

static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
{
	struct uart_state *state = drv->state + i;
	struct tty_port *port = &state->port;
	enum uart_pm_state pm_state;
	struct uart_port *uport;
	char stat_buf[32];
	unsigned int status;
	int mmio;

	mutex_lock(&port->mutex);
	uport = uart_port_check(state);
	if (!uport)
		goto out;

	mmio = uport->iotype >= UPIO_MEM;
	seq_printf(m, "%d: uart:%s %s%08llX irq:%d",
			uport->line, uart_type(uport),
			mmio ? "mmio:0x" : "port:",
			mmio ? (unsigned long long)uport->mapbase
			     : (unsigned long long)uport->iobase,
			uport->irq);

	if (uport->type == PORT_UNKNOWN) {
		seq_putc(m, '\n');
		goto out;
	}

	if (capable(CAP_SYS_ADMIN)) {
		pm_state = state->pm_state;
		if (pm_state != UART_PM_STATE_ON)
			uart_change_pm(state, UART_PM_STATE_ON);
		spin_lock_irq(&uport->lock);
		status = uport->ops->get_mctrl(uport);
		spin_unlock_irq(&uport->lock);
		if (pm_state != UART_PM_STATE_ON)
			uart_change_pm(state, pm_state);

		seq_printf(m, " tx:%d rx:%d",
				uport->icount.tx, uport->icount.rx);
		if (uport->icount.frame)
			seq_printf(m, " fe:%d",	uport->icount.frame);
		if (uport->icount.parity)
			seq_printf(m, " pe:%d",	uport->icount.parity);
		if (uport->icount.brk)
			seq_printf(m, " brk:%d", uport->icount.brk);
		if (uport->icount.overrun)
			seq_printf(m, " oe:%d", uport->icount.overrun);
		if (uport->icount.buf_overrun)
			seq_printf(m, " bo:%d", uport->icount.buf_overrun);

#define INFOBIT(bit, str) \
	if (uport->mctrl & (bit)) \
		strncat(stat_buf, (str), sizeof(stat_buf) - \
			strlen(stat_buf) - 2)
#define STATBIT(bit, str) \
	if (status & (bit)) \
		strncat(stat_buf, (str), sizeof(stat_buf) - \
		       strlen(stat_buf) - 2)

		stat_buf[0] = '\0';
		stat_buf[1] = '\0';
		INFOBIT(TIOCM_RTS, "|RTS");
		STATBIT(TIOCM_CTS, "|CTS");
		INFOBIT(TIOCM_DTR, "|DTR");
		STATBIT(TIOCM_DSR, "|DSR");
		STATBIT(TIOCM_CAR, "|CD");
		STATBIT(TIOCM_RNG, "|RI");
		if (stat_buf[0])
			stat_buf[0] = ' ';

		seq_puts(m, stat_buf);
	}
	seq_putc(m, '\n');
#undef STATBIT
#undef INFOBIT
out:
	mutex_unlock(&port->mutex);
}

static int uart_proc_show(struct seq_file *m, void *v)
{
	struct tty_driver *ttydrv = m->private;
	struct uart_driver *drv = ttydrv->driver_state;
	int i;

	seq_printf(m, "serinfo:1.0 driver%s%s revision:%s\n", "", "", "");
	for (i = 0; i < drv->nr; i++)
		uart_line_info(m, drv, i);
	return 0;
}
#endif

static void uart_port_spin_lock_init(struct uart_port *port)
{
	spin_lock_init(&port->lock);
	lockdep_set_class(&port->lock, &port_lock_key);
}

#if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
/**
 * uart_console_write - write a console message to a serial port
 * @port: the port to write the message
 * @s: array of characters
 * @count: number of characters in string to write
 * @putchar: function to write character to port
 */
void uart_console_write(struct uart_port *port, const char *s,
			unsigned int count,
			void (*putchar)(struct uart_port *, unsigned char))
{
	unsigned int i;

	for (i = 0; i < count; i++, s++) {
		if (*s == '\n')
			putchar(port, '\r');
		putchar(port, *s);
	}
}
EXPORT_SYMBOL_GPL(uart_console_write);

/**
 * uart_get_console - get uart port for console
 * @ports: ports to search in
 * @nr: number of @ports
 * @co: console to search for
 * Returns: uart_port for the console @co
 *
 * Check whether an invalid uart number has been specified (as @co->index), and
 * if so, search for the first available port that does have console support.
 */
struct uart_port * __init
uart_get_console(struct uart_port *ports, int nr, struct console *co)
{
	int idx = co->index;

	if (idx < 0 || idx >= nr || (ports[idx].iobase == 0 &&
				     ports[idx].membase == NULL))
		for (idx = 0; idx < nr; idx++)
			if (ports[idx].iobase != 0 ||
			    ports[idx].membase != NULL)
				break;

	co->index = idx;

	return ports + idx;
}

/**
 * uart_parse_earlycon - Parse earlycon options
 * @p:	     ptr to 2nd field (ie., just beyond '<name>,')
 * @iotype:  ptr for decoded iotype (out)
 * @addr:    ptr for decoded mapbase/iobase (out)
 * @options: ptr for <options> field; %NULL if not present (out)
 *
 * Decodes earlycon kernel command line parameters of the form:
 *  * earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
 *  * console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
 *
 * The optional form:
 *  * earlycon=<name>,0x<addr>,<options>
 *  * console=<name>,0x<addr>,<options>
 *
 * is also accepted; the returned @iotype will be %UPIO_MEM.
 *
 * Returns: 0 on success or -%EINVAL on failure
 */
int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
			char **options)
{
	if (strncmp(p, "mmio,", 5) == 0) {
		*iotype = UPIO_MEM;
		p += 5;
	} else if (strncmp(p, "mmio16,", 7) == 0) {
		*iotype = UPIO_MEM16;
		p += 7;
	} else if (strncmp(p, "mmio32,", 7) == 0) {
		*iotype = UPIO_MEM32;
		p += 7;
	} else if (strncmp(p, "mmio32be,", 9) == 0) {
		*iotype = UPIO_MEM32BE;
		p += 9;
	} else if (strncmp(p, "mmio32native,", 13) == 0) {
		*iotype = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) ?
			UPIO_MEM32BE : UPIO_MEM32;
		p += 13;
	} else if (strncmp(p, "io,", 3) == 0) {
		*iotype = UPIO_PORT;
		p += 3;
	} else if (strncmp(p, "0x", 2) == 0) {
		*iotype = UPIO_MEM;
	} else {
		return -EINVAL;
	}

	/*
	 * Before you replace it with kstrtoull(), think about options separator
	 * (',') it will not tolerate
	 */
	*addr = simple_strtoull(p, NULL, 0);
	p = strchr(p, ',');
	if (p)
		p++;

	*options = p;
	return 0;
}
EXPORT_SYMBOL_GPL(uart_parse_earlycon);

/**
 * uart_parse_options - Parse serial port baud/parity/bits/flow control.
 * @options: pointer to option string
 * @baud: pointer to an 'int' variable for the baud rate.
 * @parity: pointer to an 'int' variable for the parity.
 * @bits: pointer to an 'int' variable for the number of data bits.
 * @flow: pointer to an 'int' variable for the flow control character.
 *
 * uart_parse_options() decodes a string containing the serial console
 * options. The format of the string is <baud><parity><bits><flow>,
 * eg: 115200n8r
 */
void
uart_parse_options(const char *options, int *baud, int *parity,
		   int *bits, int *flow)
{
	const char *s = options;

	*baud = simple_strtoul(s, NULL, 10);
	while (*s >= '0' && *s <= '9')
		s++;
	if (*s)
		*parity = *s++;
	if (*s)
		*bits = *s++ - '0';
	if (*s)
		*flow = *s;
}
EXPORT_SYMBOL_GPL(uart_parse_options);

/**
 * uart_set_options - setup the serial console parameters
 * @port: pointer to the serial ports uart_port structure
 * @co: console pointer
 * @baud: baud rate
 * @parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
 * @bits: number of data bits
 * @flow: flow control character - 'r' (rts)
 */
int
uart_set_options(struct uart_port *port, struct console *co,
		 int baud, int parity, int bits, int flow)
{
	struct ktermios termios;
	static struct ktermios dummy;

	/*
	 * Ensure that the serial-console lock is initialised early.
	 *
	 * Note that the console-enabled check is needed because of kgdboc,
	 * which can end up calling uart_set_options() for an already enabled
	 * console via tty_find_polling_driver() and uart_poll_init().
	 */
	if (!uart_console_enabled(port) && !port->console_reinit)
		uart_port_spin_lock_init(port);

	memset(&termios, 0, sizeof(struct ktermios));

	termios.c_cflag |= CREAD | HUPCL | CLOCAL;
	tty_termios_encode_baud_rate(&termios, baud, baud);

	if (bits == 7)
		termios.c_cflag |= CS7;
	else
		termios.c_cflag |= CS8;

	switch (parity) {
	case 'o': case 'O':
		termios.c_cflag |= PARODD;
		fallthrough;
	case 'e': case 'E':
		termios.c_cflag |= PARENB;
		break;
	}

	if (flow == 'r')
		termios.c_cflag |= CRTSCTS;

	/*
	 * some uarts on other side don't support no flow control.
	 * So we set * DTR in host uart to make them happy
	 */
	port->mctrl |= TIOCM_DTR;

	port->ops->set_termios(port, &termios, &dummy);
	/*
	 * Allow the setting of the UART parameters with a NULL console
	 * too:
	 */
	if (co) {
		co->cflag = termios.c_cflag;
		co->ispeed = termios.c_ispeed;
		co->ospeed = termios.c_ospeed;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(uart_set_options);
#endif /* CONFIG_SERIAL_CORE_CONSOLE */

/**
 * uart_change_pm - set power state of the port
 *
 * @state: port descriptor
 * @pm_state: new state
 *
 * Locking: port->mutex has to be held
 */
static void uart_change_pm(struct uart_state *state,
			   enum uart_pm_state pm_state)
{
	struct uart_port *port = uart_port_check(state);

	if (state->pm_state != pm_state) {
		if (port && port->ops->pm)
			port->ops->pm(port, pm_state, state->pm_state);
		state->pm_state = pm_state;
	}
}

struct uart_match {
	struct uart_port *port;
	struct uart_driver *driver;
};

static int serial_match_port(struct device *dev, void *data)
{
	struct uart_match *match = data;
	struct tty_driver *tty_drv = match->driver->tty_driver;
	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
		match->port->line;

	return dev->devt == devt; /* Actually, only one tty per port */
}

int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
{
	struct uart_state *state = drv->state + uport->line;
	struct tty_port *port = &state->port;
	struct device *tty_dev;
	struct uart_match match = {uport, drv};

	mutex_lock(&port->mutex);

	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
	if (tty_dev && device_may_wakeup(tty_dev)) {
		enable_irq_wake(uport->irq);
		put_device(tty_dev);
		mutex_unlock(&port->mutex);
		return 0;
	}
	put_device(tty_dev);

	/*
	 * Nothing to do if the console is not suspending
	 * except stop_rx to prevent any asynchronous data
	 * over RX line. However ensure that we will be
	 * able to Re-start_rx later.
	 */
	if (!console_suspend_enabled && uart_console(uport)) {
		if (uport->ops->start_rx)
			uport->ops->stop_rx(uport);
		goto unlock;
	}

	uport->suspended = 1;

	if (tty_port_initialized(port)) {
		const struct uart_ops *ops = uport->ops;
		int tries;
		unsigned int mctrl;

		tty_port_set_suspended(port, 1);
		tty_port_set_initialized(port, 0);

		spin_lock_irq(&uport->lock);
		ops->stop_tx(uport);
		ops->set_mctrl(uport, 0);
		/* save mctrl so it can be restored on resume */
		mctrl = uport->mctrl;
		uport->mctrl = 0;
		ops->stop_rx(uport);
		spin_unlock_irq(&uport->lock);

		/*
		 * Wait for the transmitter to empty.
		 */
		for (tries = 3; !ops->tx_empty(uport) && tries; tries--)
			msleep(10);
		if (!tries)
			dev_err(uport->dev, "%s: Unable to drain transmitter\n",
				uport->name);

		ops->shutdown(uport);
		uport->mctrl = mctrl;
	}

	/*
	 * Disable the console device before suspending.
	 */
	if (uart_console(uport))
		console_stop(uport->cons);

	uart_change_pm(state, UART_PM_STATE_OFF);
unlock:
	mutex_unlock(&port->mutex);

	return 0;
}
EXPORT_SYMBOL(uart_suspend_port);

int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
{
	struct uart_state *state = drv->state + uport->line;
	struct tty_port *port = &state->port;
	struct device *tty_dev;
	struct uart_match match = {uport, drv};
	struct ktermios termios;

	mutex_lock(&port->mutex);

	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
	if (!uport->suspended && device_may_wakeup(tty_dev)) {
		if (irqd_is_wakeup_set(irq_get_irq_data((uport->irq))))
			disable_irq_wake(uport->irq);
		put_device(tty_dev);
		mutex_unlock(&port->mutex);
		return 0;
	}
	put_device(tty_dev);
	uport->suspended = 0;

	/*
	 * Re-enable the console device after suspending.
	 */
	if (uart_console(uport)) {
		/*
		 * First try to use the console cflag setting.
		 */
		memset(&termios, 0, sizeof(struct ktermios));
		termios.c_cflag = uport->cons->cflag;
		termios.c_ispeed = uport->cons->ispeed;
		termios.c_ospeed = uport->cons->ospeed;

		/*
		 * If that's unset, use the tty termios setting.
		 */
		if (port->tty && termios.c_cflag == 0)
			termios = port->tty->termios;

		if (console_suspend_enabled)
			uart_change_pm(state, UART_PM_STATE_ON);
		uport->ops->set_termios(uport, &termios, NULL);
		if (!console_suspend_enabled && uport->ops->start_rx)
			uport->ops->start_rx(uport);
		if (console_suspend_enabled)
			console_start(uport->cons);
	}

	if (tty_port_suspended(port)) {
		const struct uart_ops *ops = uport->ops;
		int ret;

		uart_change_pm(state, UART_PM_STATE_ON);
		spin_lock_irq(&uport->lock);
		ops->set_mctrl(uport, 0);
		spin_unlock_irq(&uport->lock);
		if (console_suspend_enabled || !uart_console(uport)) {
			/* Protected by port mutex for now */
			struct tty_struct *tty = port->tty;

			ret = ops->startup(uport);
			if (ret == 0) {
				if (tty)
					uart_change_speed(tty, state, NULL);
				spin_lock_irq(&uport->lock);
				ops->set_mctrl(uport, uport->mctrl);
				ops->start_tx(uport);
				spin_unlock_irq(&uport->lock);
				tty_port_set_initialized(port, 1);
			} else {
				/*
				 * Failed to resume - maybe hardware went away?
				 * Clear the "initialized" flag so we won't try
				 * to call the low level drivers shutdown method.
				 */
				uart_shutdown(tty, state);
			}
		}

		tty_port_set_suspended(port, 0);
	}

	mutex_unlock(&port->mutex);

	return 0;
}
EXPORT_SYMBOL(uart_resume_port);

static inline void
uart_report_port(struct uart_driver *drv, struct uart_port *port)
{
	char address[64];

	switch (port->iotype) {
	case UPIO_PORT:
		snprintf(address, sizeof(address), "I/O 0x%lx", port->iobase);
		break;
	case UPIO_HUB6:
		snprintf(address, sizeof(address),
			 "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
		break;
	case UPIO_MEM:
	case UPIO_MEM16:
	case UPIO_MEM32:
	case UPIO_MEM32BE:
	case UPIO_AU:
	case UPIO_TSI:
		snprintf(address, sizeof(address),
			 "MMIO 0x%llx", (unsigned long long)port->mapbase);
		break;
	default:
		strscpy(address, "*unknown*", sizeof(address));
		break;
	}

	pr_info("%s%s%s at %s (irq = %d, base_baud = %d) is a %s\n",
	       port->dev ? dev_name(port->dev) : "",
	       port->dev ? ": " : "",
	       port->name,
	       address, port->irq, port->uartclk / 16, uart_type(port));

	/* The magic multiplier feature is a bit obscure, so report it too.  */
	if (port->flags & UPF_MAGIC_MULTIPLIER)
		pr_info("%s%s%s extra baud rates supported: %d, %d",
			port->dev ? dev_name(port->dev) : "",
			port->dev ? ": " : "",
			port->name,
			port->uartclk / 8, port->uartclk / 4);
}

static void
uart_configure_port(struct uart_driver *drv, struct uart_state *state,
		    struct uart_port *port)
{
	unsigned int flags;

	/*
	 * If there isn't a port here, don't do anything further.
	 */
	if (!port->iobase && !port->mapbase && !port->membase)
		return;

	/*
	 * Now do the auto configuration stuff.  Note that config_port
	 * is expected to claim the resources and map the port for us.
	 */
	flags = 0;
	if (port->flags & UPF_AUTO_IRQ)
		flags |= UART_CONFIG_IRQ;
	if (port->flags & UPF_BOOT_AUTOCONF) {
		if (!(port->flags & UPF_FIXED_TYPE)) {
			port->type = PORT_UNKNOWN;
			flags |= UART_CONFIG_TYPE;
		}
		port->ops->config_port(port, flags);
	}

	if (port->type != PORT_UNKNOWN) {
		unsigned long flags;

		uart_report_port(drv, port);

		/* Power up port for set_mctrl() */
		uart_change_pm(state, UART_PM_STATE_ON);

		/*
		 * Ensure that the modem control lines are de-activated.
		 * keep the DTR setting that is set in uart_set_options()
		 * We probably don't need a spinlock around this, but
		 */
		spin_lock_irqsave(&port->lock, flags);
		port->mctrl &= TIOCM_DTR;
		if (port->rs485.flags & SER_RS485_ENABLED &&
		    !(port->rs485.flags & SER_RS485_RTS_AFTER_SEND))
			port->mctrl |= TIOCM_RTS;
		port->ops->set_mctrl(port, port->mctrl);
		spin_unlock_irqrestore(&port->lock, flags);

		/*
		 * If this driver supports console, and it hasn't been
		 * successfully registered yet, try to re-register it.
		 * It may be that the port was not available.
		 */
		if (port->cons && !(port->cons->flags & CON_ENABLED))
			register_console(port->cons);

		/*
		 * Power down all ports by default, except the
		 * console if we have one.
		 */
		if (!uart_console(port))
			uart_change_pm(state, UART_PM_STATE_OFF);
	}
}

#ifdef CONFIG_CONSOLE_POLL

static int uart_poll_init(struct tty_driver *driver, int line, char *options)
{
	struct uart_driver *drv = driver->driver_state;
	struct uart_state *state = drv->state + line;
	struct tty_port *tport;
	struct uart_port *port;
	int baud = 9600;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';
	int ret = 0;

	tport = &state->port;
	mutex_lock(&tport->mutex);

	port = uart_port_check(state);
	if (!port || !(port->ops->poll_get_char && port->ops->poll_put_char)) {
		ret = -1;
		goto out;
	}

	if (port->ops->poll_init) {
		/*
		 * We don't set initialized as we only initialized the hw,
		 * e.g. state->xmit is still uninitialized.
		 */
		if (!tty_port_initialized(tport))
			ret = port->ops->poll_init(port);
	}

	if (!ret && options) {
		uart_parse_options(options, &baud, &parity, &bits, &flow);
		ret = uart_set_options(port, NULL, baud, parity, bits, flow);
	}
out:
	mutex_unlock(&tport->mutex);
	return ret;
}

static int uart_poll_get_char(struct tty_driver *driver, int line)
{
	struct uart_driver *drv = driver->driver_state;
	struct uart_state *state = drv->state + line;
	struct uart_port *port;
	int ret = -1;

	port = uart_port_ref(state);
	if (port) {
		ret = port->ops->poll_get_char(port);
		uart_port_deref(port);
	}

	return ret;
}

static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
{
	struct uart_driver *drv = driver->driver_state;
	struct uart_state *state = drv->state + line;
	struct uart_port *port;

	port = uart_port_ref(state);
	if (!port)
		return;

	if (ch == '\n')
		port->ops->poll_put_char(port, '\r');
	port->ops->poll_put_char(port, ch);
	uart_port_deref(port);
}
#endif

static const struct tty_operations uart_ops = {
	.install	= uart_install,
	.open		= uart_open,
	.close		= uart_close,
	.write		= uart_write,
	.put_char	= uart_put_char,
	.flush_chars	= uart_flush_chars,
	.write_room	= uart_write_room,
	.chars_in_buffer= uart_chars_in_buffer,
	.flush_buffer	= uart_flush_buffer,
	.ioctl		= uart_ioctl,
	.throttle	= uart_throttle,
	.unthrottle	= uart_unthrottle,
	.send_xchar	= uart_send_xchar,
	.set_termios	= uart_set_termios,
	.set_ldisc	= uart_set_ldisc,
	.stop		= uart_stop,
	.start		= uart_start,
	.hangup		= uart_hangup,
	.break_ctl	= uart_break_ctl,
	.wait_until_sent= uart_wait_until_sent,
#ifdef CONFIG_PROC_FS
	.proc_show	= uart_proc_show,
#endif
	.tiocmget	= uart_tiocmget,
	.tiocmset	= uart_tiocmset,
	.set_serial	= uart_set_info_user,
	.get_serial	= uart_get_info_user,
	.get_icount	= uart_get_icount,
#ifdef CONFIG_CONSOLE_POLL
	.poll_init	= uart_poll_init,
	.poll_get_char	= uart_poll_get_char,
	.poll_put_char	= uart_poll_put_char,
#endif
};

static const struct tty_port_operations uart_port_ops = {
	.carrier_raised = uart_carrier_raised,
	.dtr_rts	= uart_dtr_rts,
	.activate	= uart_port_activate,
	.shutdown	= uart_tty_port_shutdown,
};

/**
 * uart_register_driver - register a driver with the uart core layer
 * @drv: low level driver structure
 *
 * Register a uart driver with the core driver. We in turn register with the
 * tty layer, and initialise the core driver per-port state.
 *
 * We have a proc file in /proc/tty/driver which is named after the normal
 * driver.
 *
 * @drv->port should be %NULL, and the per-port structures should be registered
 * using uart_add_one_port() after this call has succeeded.
 *
 * Locking: none, Interrupts: enabled
 */
int uart_register_driver(struct uart_driver *drv)
{
	struct tty_driver *normal;
	int i, retval = -ENOMEM;

	BUG_ON(drv->state);

	/*
	 * Maybe we should be using a slab cache for this, especially if
	 * we have a large number of ports to handle.
	 */
	drv->state = kcalloc(drv->nr, sizeof(struct uart_state), GFP_KERNEL);
	if (!drv->state)
		goto out;

	normal = tty_alloc_driver(drv->nr, TTY_DRIVER_REAL_RAW |
			TTY_DRIVER_DYNAMIC_DEV);
	if (IS_ERR(normal)) {
		retval = PTR_ERR(normal);
		goto out_kfree;
	}

	drv->tty_driver = normal;

	normal->driver_name	= drv->driver_name;
	normal->name		= drv->dev_name;
	normal->major		= drv->major;
	normal->minor_start	= drv->minor;
	normal->type		= TTY_DRIVER_TYPE_SERIAL;
	normal->subtype		= SERIAL_TYPE_NORMAL;
	normal->init_termios	= tty_std_termios;
	normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
	normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
	normal->driver_state    = drv;
	tty_set_operations(normal, &uart_ops);

	/*
	 * Initialise the UART state(s).
	 */
	for (i = 0; i < drv->nr; i++) {
		struct uart_state *state = drv->state + i;
		struct tty_port *port = &state->port;

		tty_port_init(port);
		port->ops = &uart_port_ops;
	}

	retval = tty_register_driver(normal);
	if (retval >= 0)
		return retval;

	for (i = 0; i < drv->nr; i++)
		tty_port_destroy(&drv->state[i].port);
	tty_driver_kref_put(normal);
out_kfree:
	kfree(drv->state);
out:
	return retval;
}
EXPORT_SYMBOL(uart_register_driver);

/**
 * uart_unregister_driver - remove a driver from the uart core layer
 * @drv: low level driver structure
 *
 * Remove all references to a driver from the core driver. The low level
 * driver must have removed all its ports via the uart_remove_one_port() if it
 * registered them with uart_add_one_port(). (I.e. @drv->port is %NULL.)
 *
 * Locking: none, Interrupts: enabled
 */
void uart_unregister_driver(struct uart_driver *drv)
{
	struct tty_driver *p = drv->tty_driver;
	unsigned int i;

	tty_unregister_driver(p);
	tty_driver_kref_put(p);
	for (i = 0; i < drv->nr; i++)
		tty_port_destroy(&drv->state[i].port);
	kfree(drv->state);
	drv->state = NULL;
	drv->tty_driver = NULL;
}
EXPORT_SYMBOL(uart_unregister_driver);

struct tty_driver *uart_console_device(struct console *co, int *index)
{
	struct uart_driver *p = co->data;
	*index = co->index;
	return p->tty_driver;
}
EXPORT_SYMBOL_GPL(uart_console_device);

static ssize_t uartclk_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.baud_base * 16);
}

static ssize_t type_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.type);
}

static ssize_t line_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.line);
}

static ssize_t port_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);
	unsigned long ioaddr;

	uart_get_info(port, &tmp);
	ioaddr = tmp.port;
	if (HIGH_BITS_OFFSET)
		ioaddr |= (unsigned long)tmp.port_high << HIGH_BITS_OFFSET;
	return sprintf(buf, "0x%lX\n", ioaddr);
}

static ssize_t irq_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.irq);
}

static ssize_t flags_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "0x%X\n", tmp.flags);
}

static ssize_t xmit_fifo_size_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.xmit_fifo_size);
}

static ssize_t close_delay_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.close_delay);
}

static ssize_t closing_wait_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.closing_wait);
}

static ssize_t custom_divisor_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.custom_divisor);
}

static ssize_t io_type_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.io_type);
}

static ssize_t iomem_base_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "0x%lX\n", (unsigned long)tmp.iomem_base);
}

static ssize_t iomem_reg_shift_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct serial_struct tmp;
	struct tty_port *port = dev_get_drvdata(dev);

	uart_get_info(port, &tmp);
	return sprintf(buf, "%d\n", tmp.iomem_reg_shift);
}

static ssize_t console_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct tty_port *port = dev_get_drvdata(dev);
	struct uart_state *state = container_of(port, struct uart_state, port);
	struct uart_port *uport;
	bool console = false;

	mutex_lock(&port->mutex);
	uport = uart_port_check(state);
	if (uport)
		console = uart_console_enabled(uport);
	mutex_unlock(&port->mutex);

	return sprintf(buf, "%c\n", console ? 'Y' : 'N');
}

static ssize_t console_store(struct device *dev,
	struct device_attribute *attr, const char *buf, size_t count)
{
	struct tty_port *port = dev_get_drvdata(dev);
	struct uart_state *state = container_of(port, struct uart_state, port);
	struct uart_port *uport;
	bool oldconsole, newconsole;
	int ret;

	ret = kstrtobool(buf, &newconsole);
	if (ret)
		return ret;

	mutex_lock(&port->mutex);
	uport = uart_port_check(state);
	if (uport) {
		oldconsole = uart_console_enabled(uport);
		if (oldconsole && !newconsole) {
			ret = unregister_console(uport->cons);
		} else if (!oldconsole && newconsole) {
			if (uart_console(uport)) {
				uport->console_reinit = 1;
				register_console(uport->cons);
			} else {
				ret = -ENOENT;
			}
		}
	} else {
		ret = -ENXIO;
	}
	mutex_unlock(&port->mutex);

	return ret < 0 ? ret : count;
}

static DEVICE_ATTR_RO(uartclk);
static DEVICE_ATTR_RO(type);
static DEVICE_ATTR_RO(line);
static DEVICE_ATTR_RO(port);
static DEVICE_ATTR_RO(irq);
static DEVICE_ATTR_RO(flags);
static DEVICE_ATTR_RO(xmit_fifo_size);
static DEVICE_ATTR_RO(close_delay);
static DEVICE_ATTR_RO(closing_wait);
static DEVICE_ATTR_RO(custom_divisor);
static DEVICE_ATTR_RO(io_type);
static DEVICE_ATTR_RO(iomem_base);
static DEVICE_ATTR_RO(iomem_reg_shift);
static DEVICE_ATTR_RW(console);

static struct attribute *tty_dev_attrs[] = {
	&dev_attr_uartclk.attr,
	&dev_attr_type.attr,
	&dev_attr_line.attr,
	&dev_attr_port.attr,
	&dev_attr_irq.attr,
	&dev_attr_flags.attr,
	&dev_attr_xmit_fifo_size.attr,
	&dev_attr_close_delay.attr,
	&dev_attr_closing_wait.attr,
	&dev_attr_custom_divisor.attr,
	&dev_attr_io_type.attr,
	&dev_attr_iomem_base.attr,
	&dev_attr_iomem_reg_shift.attr,
	&dev_attr_console.attr,
	NULL
};

static const struct attribute_group tty_dev_attr_group = {
	.attrs = tty_dev_attrs,
};

/**
 * uart_add_one_port - attach a driver-defined port structure
 * @drv: pointer to the uart low level driver structure for this port
 * @uport: uart port structure to use for this port.
 *
 * Context: task context, might sleep
 *
 * This allows the driver @drv to register its own uart_port structure with the
 * core driver. The main purpose is to allow the low level uart drivers to
 * expand uart_port, rather than having yet more levels of structures.
 */
int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
{
	struct uart_state *state;
	struct tty_port *port;
	int ret = 0;
	struct device *tty_dev;
	int num_groups;

	if (uport->line >= drv->nr)
		return -EINVAL;

	state = drv->state + uport->line;
	port = &state->port;

	mutex_lock(&port_mutex);
	mutex_lock(&port->mutex);
	if (state->uart_port) {
		ret = -EINVAL;
		goto out;
	}

	/* Link the port to the driver state table and vice versa */
	atomic_set(&state->refcount, 1);
	init_waitqueue_head(&state->remove_wait);
	state->uart_port = uport;
	uport->state = state;

	state->pm_state = UART_PM_STATE_UNDEFINED;
	uport->cons = drv->cons;
	uport->minor = drv->tty_driver->minor_start + uport->line;
	uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name,
				drv->tty_driver->name_base + uport->line);
	if (!uport->name) {
		ret = -ENOMEM;
		goto out;
	}

	/*
	 * If this port is in use as a console then the spinlock is already
	 * initialised.
	 */
	if (!uart_console_enabled(uport))
		uart_port_spin_lock_init(uport);

	if (uport->cons && uport->dev)
		of_console_check(uport->dev->of_node, uport->cons->name, uport->line);

	tty_port_link_device(port, drv->tty_driver, uport->line);
	uart_configure_port(drv, state, uport);

	port->console = uart_console(uport);

	num_groups = 2;
	if (uport->attr_group)
		num_groups++;

	uport->tty_groups = kcalloc(num_groups, sizeof(*uport->tty_groups),
				    GFP_KERNEL);
	if (!uport->tty_groups) {
		ret = -ENOMEM;
		goto out;
	}
	uport->tty_groups[0] = &tty_dev_attr_group;
	if (uport->attr_group)
		uport->tty_groups[1] = uport->attr_group;

	/*
	 * Register the port whether it's detected or not.  This allows
	 * setserial to be used to alter this port's parameters.
	 */
	tty_dev = tty_port_register_device_attr_serdev(port, drv->tty_driver,
			uport->line, uport->dev, port, uport->tty_groups);
	if (!IS_ERR(tty_dev)) {
		device_set_wakeup_capable(tty_dev, 1);
	} else {
		dev_err(uport->dev, "Cannot register tty device on line %d\n",
		       uport->line);
	}

	/*
	 * Ensure UPF_DEAD is not set.
	 */
	uport->flags &= ~UPF_DEAD;

 out:
	mutex_unlock(&port->mutex);
	mutex_unlock(&port_mutex);

	return ret;
}
EXPORT_SYMBOL(uart_add_one_port);

/**
 * uart_remove_one_port - detach a driver defined port structure
 * @drv: pointer to the uart low level driver structure for this port
 * @uport: uart port structure for this port
 *
 * Context: task context, might sleep
 *
 * This unhooks (and hangs up) the specified port structure from the core
 * driver. No further calls will be made to the low-level code for this port.
 */
int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
{
	struct uart_state *state = drv->state + uport->line;
	struct tty_port *port = &state->port;
	struct uart_port *uart_port;
	struct tty_struct *tty;
	int ret = 0;

	mutex_lock(&port_mutex);

	/*
	 * Mark the port "dead" - this prevents any opens from
	 * succeeding while we shut down the port.
	 */
	mutex_lock(&port->mutex);
	uart_port = uart_port_check(state);
	if (uart_port != uport)
		dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
			  uart_port, uport);

	if (!uart_port) {
		mutex_unlock(&port->mutex);
		ret = -EINVAL;
		goto out;
	}
	uport->flags |= UPF_DEAD;
	mutex_unlock(&port->mutex);

	/*
	 * Remove the devices from the tty layer
	 */
	tty_port_unregister_device(port, drv->tty_driver, uport->line);

	tty = tty_port_tty_get(port);
	if (tty) {
		tty_vhangup(port->tty);
		tty_kref_put(tty);
	}

	/*
	 * If the port is used as a console, unregister it
	 */
	if (uart_console(uport))
		unregister_console(uport->cons);

	/*
	 * Free the port IO and memory resources, if any.
	 */
	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
		uport->ops->release_port(uport);
	kfree(uport->tty_groups);
	kfree(uport->name);

	/*
	 * Indicate that there isn't a port here anymore.
	 */
	uport->type = PORT_UNKNOWN;

	mutex_lock(&port->mutex);
	WARN_ON(atomic_dec_return(&state->refcount) < 0);
	wait_event(state->remove_wait, !atomic_read(&state->refcount));
	state->uart_port = NULL;
	mutex_unlock(&port->mutex);
out:
	mutex_unlock(&port_mutex);

	return ret;
}
EXPORT_SYMBOL(uart_remove_one_port);

/**
 * uart_match_port - are the two ports equivalent?
 * @port1: first port
 * @port2: second port
 *
 * This utility function can be used to determine whether two uart_port
 * structures describe the same port.
 */
bool uart_match_port(const struct uart_port *port1,
		const struct uart_port *port2)
{
	if (port1->iotype != port2->iotype)
		return false;

	switch (port1->iotype) {
	case UPIO_PORT:
		return port1->iobase == port2->iobase;
	case UPIO_HUB6:
		return port1->iobase == port2->iobase &&
		       port1->hub6   == port2->hub6;
	case UPIO_MEM:
	case UPIO_MEM16:
	case UPIO_MEM32:
	case UPIO_MEM32BE:
	case UPIO_AU:
	case UPIO_TSI:
		return port1->mapbase == port2->mapbase;
	}

	return false;
}
EXPORT_SYMBOL(uart_match_port);

/**
 * uart_handle_dcd_change - handle a change of carrier detect state
 * @uport: uart_port structure for the open port
 * @status: new carrier detect status, nonzero if active
 *
 * Caller must hold uport->lock.
 */
void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
{
	struct tty_port *port = &uport->state->port;
	struct tty_struct *tty = port->tty;
	struct tty_ldisc *ld;

	lockdep_assert_held_once(&uport->lock);

	if (tty) {
		ld = tty_ldisc_ref(tty);
		if (ld) {
			if (ld->ops->dcd_change)
				ld->ops->dcd_change(tty, status);
			tty_ldisc_deref(ld);
		}
	}

	uport->icount.dcd++;

	if (uart_dcd_enabled(uport)) {
		if (status)
			wake_up_interruptible(&port->open_wait);
		else if (tty)
			tty_hangup(tty);
	}
}
EXPORT_SYMBOL_GPL(uart_handle_dcd_change);

/**
 * uart_handle_cts_change - handle a change of clear-to-send state
 * @uport: uart_port structure for the open port
 * @status: new clear to send status, nonzero if active
 *
 * Caller must hold uport->lock.
 */
void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
{
	lockdep_assert_held_once(&uport->lock);

	uport->icount.cts++;

	if (uart_softcts_mode(uport)) {
		if (uport->hw_stopped) {
			if (status) {
				uport->hw_stopped = 0;
				uport->ops->start_tx(uport);
				uart_write_wakeup(uport);
			}
		} else {
			if (!status) {
				uport->hw_stopped = 1;
				uport->ops->stop_tx(uport);
			}
		}

	}
}
EXPORT_SYMBOL_GPL(uart_handle_cts_change);

/**
 * uart_insert_char - push a char to the uart layer
 *
 * User is responsible to call tty_flip_buffer_push when they are done with
 * insertion.
 *
 * @port: corresponding port
 * @status: state of the serial port RX buffer (LSR for 8250)
 * @overrun: mask of overrun bits in @status
 * @ch: character to push
 * @flag: flag for the character (see TTY_NORMAL and friends)
 */
void uart_insert_char(struct uart_port *port, unsigned int status,
		 unsigned int overrun, unsigned int ch, unsigned int flag)
{
	struct tty_port *tport = &port->state->port;

	if ((status & port->ignore_status_mask & ~overrun) == 0)
		if (tty_insert_flip_char(tport, ch, flag) == 0)
			++port->icount.buf_overrun;

	/*
	 * Overrun is special.  Since it's reported immediately,
	 * it doesn't affect the current character.
	 */
	if (status & ~port->ignore_status_mask & overrun)
		if (tty_insert_flip_char(tport, 0, TTY_OVERRUN) == 0)
			++port->icount.buf_overrun;
}
EXPORT_SYMBOL_GPL(uart_insert_char);

#ifdef CONFIG_MAGIC_SYSRQ_SERIAL
static const char sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;

static void uart_sysrq_on(struct work_struct *w)
{
	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);

	sysrq_toggle_support(1);
	pr_info("SysRq is enabled by magic sequence '%*pE' on serial\n",
		sysrq_toggle_seq_len, sysrq_toggle_seq);
}
static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);

/**
 * uart_try_toggle_sysrq - Enables SysRq from serial line
 * @port: uart_port structure where char(s) after BREAK met
 * @ch: new character in the sequence after received BREAK
 *
 * Enables magic SysRq when the required sequence is met on port
 * (see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
 *
 * Returns: %false if @ch is out of enabling sequence and should be
 * handled some other way, %true if @ch was consumed.
 */
bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
{
	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);

	if (!sysrq_toggle_seq_len)
		return false;

	BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= U8_MAX);
	if (sysrq_toggle_seq[port->sysrq_seq] != ch) {
		port->sysrq_seq = 0;
		return false;
	}

	if (++port->sysrq_seq < sysrq_toggle_seq_len) {
		port->sysrq = jiffies + SYSRQ_TIMEOUT;
		return true;
	}

	schedule_work(&sysrq_enable_work);

	port->sysrq = 0;
	return true;
}
EXPORT_SYMBOL_GPL(uart_try_toggle_sysrq);
#endif

/**
 * uart_get_rs485_mode() - retrieve rs485 properties for given uart
 * @port: uart device's target port
 *
 * This function implements the device tree binding described in
 * Documentation/devicetree/bindings/serial/rs485.txt.
 */
int uart_get_rs485_mode(struct uart_port *port)
{
	struct serial_rs485 *rs485conf = &port->rs485;
	struct device *dev = port->dev;
	u32 rs485_delay[2];
	int ret;

	ret = device_property_read_u32_array(dev, "rs485-rts-delay",
					     rs485_delay, 2);
	if (!ret) {
		rs485conf->delay_rts_before_send = rs485_delay[0];
		rs485conf->delay_rts_after_send = rs485_delay[1];
	} else {
		rs485conf->delay_rts_before_send = 0;
		rs485conf->delay_rts_after_send = 0;
	}

	uart_sanitize_serial_rs485_delays(port, rs485conf);

	/*
	 * Clear full-duplex and enabled flags, set RTS polarity to active high
	 * to get to a defined state with the following properties:
	 */
	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
			      SER_RS485_TERMINATE_BUS |
			      SER_RS485_RTS_AFTER_SEND);
	rs485conf->flags |= SER_RS485_RTS_ON_SEND;

	if (device_property_read_bool(dev, "rs485-rx-during-tx"))
		rs485conf->flags |= SER_RS485_RX_DURING_TX;

	if (device_property_read_bool(dev, "linux,rs485-enabled-at-boot-time"))
		rs485conf->flags |= SER_RS485_ENABLED;

	if (device_property_read_bool(dev, "rs485-rts-active-low")) {
		rs485conf->flags &= ~SER_RS485_RTS_ON_SEND;
		rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
	}

	/*
	 * Disabling termination by default is the safe choice:  Else if many
	 * bus participants enable it, no communication is possible at all.
	 * Works fine for short cables and users may enable for longer cables.
	 */
	port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
							GPIOD_OUT_LOW);
	if (IS_ERR(port->rs485_term_gpio)) {
		ret = PTR_ERR(port->rs485_term_gpio);
		port->rs485_term_gpio = NULL;
		return dev_err_probe(dev, ret, "Cannot get rs485-term-gpios\n");
	}
	if (port->rs485_term_gpio)
		port->rs485_supported.flags |= SER_RS485_TERMINATE_BUS;

	return 0;
}
EXPORT_SYMBOL_GPL(uart_get_rs485_mode);

/* Compile-time assertions for serial_rs485 layout */
static_assert(offsetof(struct serial_rs485, padding) ==
              (offsetof(struct serial_rs485, delay_rts_after_send) + sizeof(__u32)));
static_assert(offsetof(struct serial_rs485, padding1) ==
	      offsetof(struct serial_rs485, padding[1]));
static_assert((offsetof(struct serial_rs485, padding[4]) + sizeof(__u32)) ==
	      sizeof(struct serial_rs485));

MODULE_DESCRIPTION("Serial driver core");
MODULE_LICENSE("GPL");