aboutsummaryrefslogtreecommitdiff
path: root/drivers/acpi/ec.c
blob: 73c76d646064700dc1bb51905b4dbc70b415aabf (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
/*
 *  ec.c - ACPI Embedded Controller Driver (v3)
 *
 *  Copyright (C) 2001-2015 Intel Corporation
 *    Author: 2014, 2015 Lv Zheng <lv.zheng@intel.com>
 *            2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
 *            2006       Denis Sadykov <denis.m.sadykov@intel.com>
 *            2004       Luming Yu <luming.yu@intel.com>
 *            2001, 2002 Andy Grover <andrew.grover@intel.com>
 *            2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *  Copyright (C) 2008      Alexey Starikovskiy <astarikovskiy@suse.de>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

/* Uncomment next line to get verbose printout */
/* #define DEBUG */
#define pr_fmt(fmt) "ACPI : EC: " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/dmi.h>
#include <asm/io.h>

#include "internal.h"

#define ACPI_EC_CLASS			"embedded_controller"
#define ACPI_EC_DEVICE_NAME		"Embedded Controller"
#define ACPI_EC_FILE_INFO		"info"

/* EC status register */
#define ACPI_EC_FLAG_OBF	0x01	/* Output buffer full */
#define ACPI_EC_FLAG_IBF	0x02	/* Input buffer full */
#define ACPI_EC_FLAG_CMD	0x08	/* Input buffer contains a command */
#define ACPI_EC_FLAG_BURST	0x10	/* burst mode */
#define ACPI_EC_FLAG_SCI	0x20	/* EC-SCI occurred */

/*
 * The SCI_EVT clearing timing is not defined by the ACPI specification.
 * This leads to lots of practical timing issues for the host EC driver.
 * The following variations are defined (from the target EC firmware's
 * perspective):
 * STATUS: After indicating SCI_EVT edge triggered IRQ to the host, the
 *         target can clear SCI_EVT at any time so long as the host can see
 *         the indication by reading the status register (EC_SC). So the
 *         host should re-check SCI_EVT after the first time the SCI_EVT
 *         indication is seen, which is the same time the query request
 *         (QR_EC) is written to the command register (EC_CMD). SCI_EVT set
 *         at any later time could indicate another event. Normally such
 *         kind of EC firmware has implemented an event queue and will
 *         return 0x00 to indicate "no outstanding event".
 * QUERY: After seeing the query request (QR_EC) written to the command
 *        register (EC_CMD) by the host and having prepared the responding
 *        event value in the data register (EC_DATA), the target can safely
 *        clear SCI_EVT because the target can confirm that the current
 *        event is being handled by the host. The host then should check
 *        SCI_EVT right after reading the event response from the data
 *        register (EC_DATA).
 * EVENT: After seeing the event response read from the data register
 *        (EC_DATA) by the host, the target can clear SCI_EVT. As the
 *        target requires time to notice the change in the data register
 *        (EC_DATA), the host may be required to wait additional guarding
 *        time before checking the SCI_EVT again. Such guarding may not be
 *        necessary if the host is notified via another IRQ.
 */
#define ACPI_EC_EVT_TIMING_STATUS	0x00
#define ACPI_EC_EVT_TIMING_QUERY	0x01
#define ACPI_EC_EVT_TIMING_EVENT	0x02

/* EC commands */
enum ec_command {
	ACPI_EC_COMMAND_READ = 0x80,
	ACPI_EC_COMMAND_WRITE = 0x81,
	ACPI_EC_BURST_ENABLE = 0x82,
	ACPI_EC_BURST_DISABLE = 0x83,
	ACPI_EC_COMMAND_QUERY = 0x84,
};

#define ACPI_EC_DELAY		500	/* Wait 500ms max. during EC ops */
#define ACPI_EC_UDELAY_GLK	1000	/* Wait 1ms max. to get global lock */
#define ACPI_EC_UDELAY_POLL	550	/* Wait 1ms for EC transaction polling */
#define ACPI_EC_CLEAR_MAX	100	/* Maximum number of events to query
					 * when trying to clear the EC */

enum {
	EC_FLAGS_QUERY_PENDING,		/* Query is pending */
	EC_FLAGS_QUERY_GUARDING,	/* Guard for SCI_EVT check */
	EC_FLAGS_GPE_HANDLER_INSTALLED,	/* GPE handler installed */
	EC_FLAGS_EC_HANDLER_INSTALLED,	/* OpReg handler installed */
	EC_FLAGS_STARTED,		/* Driver is started */
	EC_FLAGS_STOPPED,		/* Driver is stopped */
	EC_FLAGS_COMMAND_STORM,		/* GPE storms occurred to the
					 * current command processing */
};

#define ACPI_EC_COMMAND_POLL		0x01 /* Available for command byte */
#define ACPI_EC_COMMAND_COMPLETE	0x02 /* Completed last byte */

/* ec.c is compiled in acpi namespace so this shows up as acpi.ec_delay param */
static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY;
module_param(ec_delay, uint, 0644);
MODULE_PARM_DESC(ec_delay, "Timeout(ms) waited until an EC command completes");

static bool ec_busy_polling __read_mostly;
module_param(ec_busy_polling, bool, 0644);
MODULE_PARM_DESC(ec_busy_polling, "Use busy polling to advance EC transaction");

static unsigned int ec_polling_guard __read_mostly = ACPI_EC_UDELAY_POLL;
module_param(ec_polling_guard, uint, 0644);
MODULE_PARM_DESC(ec_polling_guard, "Guard time(us) between EC accesses in polling modes");

static unsigned int ec_event_clearing __read_mostly = ACPI_EC_EVT_TIMING_QUERY;

/*
 * If the number of false interrupts per one transaction exceeds
 * this threshold, will think there is a GPE storm happened and
 * will disable the GPE for normal transaction.
 */
static unsigned int ec_storm_threshold  __read_mostly = 8;
module_param(ec_storm_threshold, uint, 0644);
MODULE_PARM_DESC(ec_storm_threshold, "Maxim false GPE numbers not considered as GPE storm");

struct acpi_ec_query_handler {
	struct list_head node;
	acpi_ec_query_func func;
	acpi_handle handle;
	void *data;
	u8 query_bit;
	struct kref kref;
};

struct transaction {
	const u8 *wdata;
	u8 *rdata;
	unsigned short irq_count;
	u8 command;
	u8 wi;
	u8 ri;
	u8 wlen;
	u8 rlen;
	u8 flags;
};

struct acpi_ec_query {
	struct transaction transaction;
	struct work_struct work;
	struct acpi_ec_query_handler *handler;
};

static int acpi_ec_query(struct acpi_ec *ec, u8 *data);
static void advance_transaction(struct acpi_ec *ec);
static void acpi_ec_event_handler(struct work_struct *work);
static void acpi_ec_event_processor(struct work_struct *work);

struct acpi_ec *boot_ec, *first_ec;
EXPORT_SYMBOL(first_ec);

static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */
static int EC_FLAGS_CORRECT_ECDT; /* Needs ECDT port address correction */

/* --------------------------------------------------------------------------
 *                           Logging/Debugging
 * -------------------------------------------------------------------------- */

/*
 * Splitters used by the developers to track the boundary of the EC
 * handling processes.
 */
#ifdef DEBUG
#define EC_DBG_SEP	" "
#define EC_DBG_DRV	"+++++"
#define EC_DBG_STM	"====="
#define EC_DBG_REQ	"*****"
#define EC_DBG_EVT	"#####"
#else
#define EC_DBG_SEP	""
#define EC_DBG_DRV
#define EC_DBG_STM
#define EC_DBG_REQ
#define EC_DBG_EVT
#endif

#define ec_log_raw(fmt, ...) \
	pr_info(fmt "\n", ##__VA_ARGS__)
#define ec_dbg_raw(fmt, ...) \
	pr_debug(fmt "\n", ##__VA_ARGS__)
#define ec_log(filter, fmt, ...) \
	ec_log_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
#define ec_dbg(filter, fmt, ...) \
	ec_dbg_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)

#define ec_log_drv(fmt, ...) \
	ec_log(EC_DBG_DRV, fmt, ##__VA_ARGS__)
#define ec_dbg_drv(fmt, ...) \
	ec_dbg(EC_DBG_DRV, fmt, ##__VA_ARGS__)
#define ec_dbg_stm(fmt, ...) \
	ec_dbg(EC_DBG_STM, fmt, ##__VA_ARGS__)
#define ec_dbg_req(fmt, ...) \
	ec_dbg(EC_DBG_REQ, fmt, ##__VA_ARGS__)
#define ec_dbg_evt(fmt, ...) \
	ec_dbg(EC_DBG_EVT, fmt, ##__VA_ARGS__)
#define ec_dbg_ref(ec, fmt, ...) \
	ec_dbg_raw("%lu: " fmt, ec->reference_count, ## __VA_ARGS__)

/* --------------------------------------------------------------------------
 *                           Device Flags
 * -------------------------------------------------------------------------- */

static bool acpi_ec_started(struct acpi_ec *ec)
{
	return test_bit(EC_FLAGS_STARTED, &ec->flags) &&
	       !test_bit(EC_FLAGS_STOPPED, &ec->flags);
}

static bool acpi_ec_flushed(struct acpi_ec *ec)
{
	return ec->reference_count == 1;
}

/* --------------------------------------------------------------------------
 *                           EC Registers
 * -------------------------------------------------------------------------- */

static inline u8 acpi_ec_read_status(struct acpi_ec *ec)
{
	u8 x = inb(ec->command_addr);

	ec_dbg_raw("EC_SC(R) = 0x%2.2x "
		   "SCI_EVT=%d BURST=%d CMD=%d IBF=%d OBF=%d",
		   x,
		   !!(x & ACPI_EC_FLAG_SCI),
		   !!(x & ACPI_EC_FLAG_BURST),
		   !!(x & ACPI_EC_FLAG_CMD),
		   !!(x & ACPI_EC_FLAG_IBF),
		   !!(x & ACPI_EC_FLAG_OBF));
	return x;
}

static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
{
	u8 x = inb(ec->data_addr);

	ec->timestamp = jiffies;
	ec_dbg_raw("EC_DATA(R) = 0x%2.2x", x);
	return x;
}

static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
{
	ec_dbg_raw("EC_SC(W) = 0x%2.2x", command);
	outb(command, ec->command_addr);
	ec->timestamp = jiffies;
}

static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
{
	ec_dbg_raw("EC_DATA(W) = 0x%2.2x", data);
	outb(data, ec->data_addr);
	ec->timestamp = jiffies;
}

#ifdef DEBUG
static const char *acpi_ec_cmd_string(u8 cmd)
{
	switch (cmd) {
	case 0x80:
		return "RD_EC";
	case 0x81:
		return "WR_EC";
	case 0x82:
		return "BE_EC";
	case 0x83:
		return "BD_EC";
	case 0x84:
		return "QR_EC";
	}
	return "UNKNOWN";
}
#else
#define acpi_ec_cmd_string(cmd)		"UNDEF"
#endif

/* --------------------------------------------------------------------------
 *                           GPE Registers
 * -------------------------------------------------------------------------- */

static inline bool acpi_ec_is_gpe_raised(struct acpi_ec *ec)
{
	acpi_event_status gpe_status = 0;

	(void)acpi_get_gpe_status(NULL, ec->gpe, &gpe_status);
	return (gpe_status & ACPI_EVENT_FLAG_STATUS_SET) ? true : false;
}

static inline void acpi_ec_enable_gpe(struct acpi_ec *ec, bool open)
{
	if (open)
		acpi_enable_gpe(NULL, ec->gpe);
	else {
		BUG_ON(ec->reference_count < 1);
		acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_ENABLE);
	}
	if (acpi_ec_is_gpe_raised(ec)) {
		/*
		 * On some platforms, EN=1 writes cannot trigger GPE. So
		 * software need to manually trigger a pseudo GPE event on
		 * EN=1 writes.
		 */
		ec_dbg_raw("Polling quirk");
		advance_transaction(ec);
	}
}

static inline void acpi_ec_disable_gpe(struct acpi_ec *ec, bool close)
{
	if (close)
		acpi_disable_gpe(NULL, ec->gpe);
	else {
		BUG_ON(ec->reference_count < 1);
		acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_DISABLE);
	}
}

static inline void acpi_ec_clear_gpe(struct acpi_ec *ec)
{
	/*
	 * GPE STS is a W1C register, which means:
	 * 1. Software can clear it without worrying about clearing other
	 *    GPEs' STS bits when the hardware sets them in parallel.
	 * 2. As long as software can ensure only clearing it when it is
	 *    set, hardware won't set it in parallel.
	 * So software can clear GPE in any contexts.
	 * Warning: do not move the check into advance_transaction() as the
	 * EC commands will be sent without GPE raised.
	 */
	if (!acpi_ec_is_gpe_raised(ec))
		return;
	acpi_clear_gpe(NULL, ec->gpe);
}

/* --------------------------------------------------------------------------
 *                           Transaction Management
 * -------------------------------------------------------------------------- */

static void acpi_ec_submit_request(struct acpi_ec *ec)
{
	ec->reference_count++;
	if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags) &&
	    ec->reference_count == 1)
		acpi_ec_enable_gpe(ec, true);
}

static void acpi_ec_complete_request(struct acpi_ec *ec)
{
	bool flushed = false;

	ec->reference_count--;
	if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags) &&
	    ec->reference_count == 0)
		acpi_ec_disable_gpe(ec, true);
	flushed = acpi_ec_flushed(ec);
	if (flushed)
		wake_up(&ec->wait);
}

static void acpi_ec_set_storm(struct acpi_ec *ec, u8 flag)
{
	if (!test_bit(flag, &ec->flags)) {
		acpi_ec_disable_gpe(ec, false);
		ec_dbg_drv("Polling enabled");
		set_bit(flag, &ec->flags);
	}
}

static void acpi_ec_clear_storm(struct acpi_ec *ec, u8 flag)
{
	if (test_bit(flag, &ec->flags)) {
		clear_bit(flag, &ec->flags);
		acpi_ec_enable_gpe(ec, false);
		ec_dbg_drv("Polling disabled");
	}
}

/*
 * acpi_ec_submit_flushable_request() - Increase the reference count unless
 *                                      the flush operation is not in
 *                                      progress
 * @ec: the EC device
 *
 * This function must be used before taking a new action that should hold
 * the reference count.  If this function returns false, then the action
 * must be discarded or it will prevent the flush operation from being
 * completed.
 */
static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
{
	if (!acpi_ec_started(ec))
		return false;
	acpi_ec_submit_request(ec);
	return true;
}

static void acpi_ec_submit_query(struct acpi_ec *ec)
{
	if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
		ec_dbg_evt("Command(%s) submitted/blocked",
			   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
		ec->nr_pending_queries++;
		schedule_work(&ec->work);
	}
}

static void acpi_ec_complete_query(struct acpi_ec *ec)
{
	if (test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
		clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
		ec_dbg_evt("Command(%s) unblocked",
			   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
	}
}

static bool acpi_ec_guard_event(struct acpi_ec *ec)
{
	bool guarded = true;
	unsigned long flags;

	spin_lock_irqsave(&ec->lock, flags);
	/*
	 * If firmware SCI_EVT clearing timing is "event", we actually
	 * don't know when the SCI_EVT will be cleared by firmware after
	 * evaluating _Qxx, so we need to re-check SCI_EVT after waiting an
	 * acceptable period.
	 *
	 * The guarding period begins when EC_FLAGS_QUERY_PENDING is
	 * flagged, which means SCI_EVT check has just been performed.
	 * But if the current transaction is ACPI_EC_COMMAND_QUERY, the
	 * guarding should have already been performed (via
	 * EC_FLAGS_QUERY_GUARDING) and should not be applied so that the
	 * ACPI_EC_COMMAND_QUERY transaction can be transitioned into
	 * ACPI_EC_COMMAND_POLL state immediately.
	 */
	if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
	    ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY ||
	    !test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags) ||
	    (ec->curr && ec->curr->command == ACPI_EC_COMMAND_QUERY))
		guarded = false;
	spin_unlock_irqrestore(&ec->lock, flags);
	return guarded;
}

static int ec_transaction_polled(struct acpi_ec *ec)
{
	unsigned long flags;
	int ret = 0;

	spin_lock_irqsave(&ec->lock, flags);
	if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_POLL))
		ret = 1;
	spin_unlock_irqrestore(&ec->lock, flags);
	return ret;
}

static int ec_transaction_completed(struct acpi_ec *ec)
{
	unsigned long flags;
	int ret = 0;

	spin_lock_irqsave(&ec->lock, flags);
	if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE))
		ret = 1;
	spin_unlock_irqrestore(&ec->lock, flags);
	return ret;
}

static inline void ec_transaction_transition(struct acpi_ec *ec, unsigned long flag)
{
	ec->curr->flags |= flag;
	if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
		if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS &&
		    flag == ACPI_EC_COMMAND_POLL)
			acpi_ec_complete_query(ec);
		if (ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY &&
		    flag == ACPI_EC_COMMAND_COMPLETE)
			acpi_ec_complete_query(ec);
		if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
		    flag == ACPI_EC_COMMAND_COMPLETE)
			set_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
	}
}

static void advance_transaction(struct acpi_ec *ec)
{
	struct transaction *t;
	u8 status;
	bool wakeup = false;

	ec_dbg_stm("%s (%d)", in_interrupt() ? "IRQ" : "TASK",
		   smp_processor_id());
	/*
	 * By always clearing STS before handling all indications, we can
	 * ensure a hardware STS 0->1 change after this clearing can always
	 * trigger a GPE interrupt.
	 */
	acpi_ec_clear_gpe(ec);
	status = acpi_ec_read_status(ec);
	t = ec->curr;
	/*
	 * Another IRQ or a guarded polling mode advancement is detected,
	 * the next QR_EC submission is then allowed.
	 */
	if (!t || !(t->flags & ACPI_EC_COMMAND_POLL)) {
		if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
		    (!ec->nr_pending_queries ||
		     test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags))) {
			clear_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
			acpi_ec_complete_query(ec);
		}
	}
	if (!t)
		goto err;
	if (t->flags & ACPI_EC_COMMAND_POLL) {
		if (t->wlen > t->wi) {
			if ((status & ACPI_EC_FLAG_IBF) == 0)
				acpi_ec_write_data(ec, t->wdata[t->wi++]);
			else
				goto err;
		} else if (t->rlen > t->ri) {
			if ((status & ACPI_EC_FLAG_OBF) == 1) {
				t->rdata[t->ri++] = acpi_ec_read_data(ec);
				if (t->rlen == t->ri) {
					ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
					if (t->command == ACPI_EC_COMMAND_QUERY)
						ec_dbg_evt("Command(%s) completed by hardware",
							   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
					wakeup = true;
				}
			} else
				goto err;
		} else if (t->wlen == t->wi &&
			   (status & ACPI_EC_FLAG_IBF) == 0) {
			ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
			wakeup = true;
		}
		goto out;
	} else {
		if (EC_FLAGS_QUERY_HANDSHAKE &&
		    !(status & ACPI_EC_FLAG_SCI) &&
		    (t->command == ACPI_EC_COMMAND_QUERY)) {
			ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
			t->rdata[t->ri++] = 0x00;
			ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
			ec_dbg_evt("Command(%s) completed by software",
				   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
			wakeup = true;
		} else if ((status & ACPI_EC_FLAG_IBF) == 0) {
			acpi_ec_write_cmd(ec, t->command);
			ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
		} else
			goto err;
		goto out;
	}
err:
	/*
	 * If SCI bit is set, then don't think it's a false IRQ
	 * otherwise will take a not handled IRQ as a false one.
	 */
	if (!(status & ACPI_EC_FLAG_SCI)) {
		if (in_interrupt() && t) {
			if (t->irq_count < ec_storm_threshold)
				++t->irq_count;
			/* Allow triggering on 0 threshold */
			if (t->irq_count == ec_storm_threshold)
				acpi_ec_set_storm(ec, EC_FLAGS_COMMAND_STORM);
		}
	}
out:
	if (status & ACPI_EC_FLAG_SCI)
		acpi_ec_submit_query(ec);
	if (wakeup && in_interrupt())
		wake_up(&ec->wait);
}

static void start_transaction(struct acpi_ec *ec)
{
	ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
	ec->curr->flags = 0;
}

static int ec_guard(struct acpi_ec *ec)
{
	unsigned long guard = usecs_to_jiffies(ec_polling_guard);
	unsigned long timeout = ec->timestamp + guard;

	/* Ensure guarding period before polling EC status */
	do {
		if (ec_busy_polling) {
			/* Perform busy polling */
			if (ec_transaction_completed(ec))
				return 0;
			udelay(jiffies_to_usecs(guard));
		} else {
			/*
			 * Perform wait polling
			 * 1. Wait the transaction to be completed by the
			 *    GPE handler after the transaction enters
			 *    ACPI_EC_COMMAND_POLL state.
			 * 2. A special guarding logic is also required
			 *    for event clearing mode "event" before the
			 *    transaction enters ACPI_EC_COMMAND_POLL
			 *    state.
			 */
			if (!ec_transaction_polled(ec) &&
			    !acpi_ec_guard_event(ec))
				break;
			if (wait_event_timeout(ec->wait,
					       ec_transaction_completed(ec),
					       guard))
				return 0;
		}
	} while (time_before(jiffies, timeout));
	return -ETIME;
}

static int ec_poll(struct acpi_ec *ec)
{
	unsigned long flags;
	int repeat = 5; /* number of command restarts */

	while (repeat--) {
		unsigned long delay = jiffies +
			msecs_to_jiffies(ec_delay);
		do {
			if (!ec_guard(ec))
				return 0;
			spin_lock_irqsave(&ec->lock, flags);
			advance_transaction(ec);
			spin_unlock_irqrestore(&ec->lock, flags);
		} while (time_before(jiffies, delay));
		pr_debug("controller reset, restart transaction\n");
		spin_lock_irqsave(&ec->lock, flags);
		start_transaction(ec);
		spin_unlock_irqrestore(&ec->lock, flags);
	}
	return -ETIME;
}

static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
					struct transaction *t)
{
	unsigned long tmp;
	int ret = 0;

	/* start transaction */
	spin_lock_irqsave(&ec->lock, tmp);
	/* Enable GPE for command processing (IBF=0/OBF=1) */
	if (!acpi_ec_submit_flushable_request(ec)) {
		ret = -EINVAL;
		goto unlock;
	}
	ec_dbg_ref(ec, "Increase command");
	/* following two actions should be kept atomic */
	ec->curr = t;
	ec_dbg_req("Command(%s) started", acpi_ec_cmd_string(t->command));
	start_transaction(ec);
	spin_unlock_irqrestore(&ec->lock, tmp);

	ret = ec_poll(ec);

	spin_lock_irqsave(&ec->lock, tmp);
	if (t->irq_count == ec_storm_threshold)
		acpi_ec_clear_storm(ec, EC_FLAGS_COMMAND_STORM);
	ec_dbg_req("Command(%s) stopped", acpi_ec_cmd_string(t->command));
	ec->curr = NULL;
	/* Disable GPE for command processing (IBF=0/OBF=1) */
	acpi_ec_complete_request(ec);
	ec_dbg_ref(ec, "Decrease command");
unlock:
	spin_unlock_irqrestore(&ec->lock, tmp);
	return ret;
}

static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
{
	int status;
	u32 glk;

	if (!ec || (!t) || (t->wlen && !t->wdata) || (t->rlen && !t->rdata))
		return -EINVAL;
	if (t->rdata)
		memset(t->rdata, 0, t->rlen);

	mutex_lock(&ec->mutex);
	if (ec->global_lock) {
		status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
		if (ACPI_FAILURE(status)) {
			status = -ENODEV;
			goto unlock;
		}
	}

	status = acpi_ec_transaction_unlocked(ec, t);

	if (ec->global_lock)
		acpi_release_global_lock(glk);
unlock:
	mutex_unlock(&ec->mutex);
	return status;
}

static int acpi_ec_burst_enable(struct acpi_ec *ec)
{
	u8 d;
	struct transaction t = {.command = ACPI_EC_BURST_ENABLE,
				.wdata = NULL, .rdata = &d,
				.wlen = 0, .rlen = 1};

	return acpi_ec_transaction(ec, &t);
}

static int acpi_ec_burst_disable(struct acpi_ec *ec)
{
	struct transaction t = {.command = ACPI_EC_BURST_DISABLE,
				.wdata = NULL, .rdata = NULL,
				.wlen = 0, .rlen = 0};

	return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
				acpi_ec_transaction(ec, &t) : 0;
}

static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 *data)
{
	int result;
	u8 d;
	struct transaction t = {.command = ACPI_EC_COMMAND_READ,
				.wdata = &address, .rdata = &d,
				.wlen = 1, .rlen = 1};

	result = acpi_ec_transaction(ec, &t);
	*data = d;
	return result;
}

static int acpi_ec_write(struct acpi_ec *ec, u8 address, u8 data)
{
	u8 wdata[2] = { address, data };
	struct transaction t = {.command = ACPI_EC_COMMAND_WRITE,
				.wdata = wdata, .rdata = NULL,
				.wlen = 2, .rlen = 0};

	return acpi_ec_transaction(ec, &t);
}

int ec_read(u8 addr, u8 *val)
{
	int err;
	u8 temp_data;

	if (!first_ec)
		return -ENODEV;

	err = acpi_ec_read(first_ec, addr, &temp_data);

	if (!err) {
		*val = temp_data;
		return 0;
	}
	return err;
}
EXPORT_SYMBOL(ec_read);

int ec_write(u8 addr, u8 val)
{
	int err;

	if (!first_ec)
		return -ENODEV;

	err = acpi_ec_write(first_ec, addr, val);

	return err;
}
EXPORT_SYMBOL(ec_write);

int ec_transaction(u8 command,
		   const u8 *wdata, unsigned wdata_len,
		   u8 *rdata, unsigned rdata_len)
{
	struct transaction t = {.command = command,
				.wdata = wdata, .rdata = rdata,
				.wlen = wdata_len, .rlen = rdata_len};

	if (!first_ec)
		return -ENODEV;

	return acpi_ec_transaction(first_ec, &t);
}
EXPORT_SYMBOL(ec_transaction);

/* Get the handle to the EC device */
acpi_handle ec_get_handle(void)
{
	if (!first_ec)
		return NULL;
	return first_ec->handle;
}
EXPORT_SYMBOL(ec_get_handle);

/*
 * Process _Q events that might have accumulated in the EC.
 * Run with locked ec mutex.
 */
static void acpi_ec_clear(struct acpi_ec *ec)
{
	int i, status;
	u8 value = 0;

	for (i = 0; i < ACPI_EC_CLEAR_MAX; i++) {
		status = acpi_ec_query(ec, &value);
		if (status || !value)
			break;
	}

	if (unlikely(i == ACPI_EC_CLEAR_MAX))
		pr_warn("Warning: Maximum of %d stale EC events cleared\n", i);
	else
		pr_info("%d stale EC events cleared\n", i);
}

static void acpi_ec_start(struct acpi_ec *ec, bool resuming)
{
	unsigned long flags;

	spin_lock_irqsave(&ec->lock, flags);
	if (!test_and_set_bit(EC_FLAGS_STARTED, &ec->flags)) {
		ec_dbg_drv("Starting EC");
		/* Enable GPE for event processing (SCI_EVT=1) */
		if (!resuming) {
			acpi_ec_submit_request(ec);
			ec_dbg_ref(ec, "Increase driver");
		}
		ec_log_drv("EC started");
	}
	spin_unlock_irqrestore(&ec->lock, flags);
}

static bool acpi_ec_stopped(struct acpi_ec *ec)
{
	unsigned long flags;
	bool flushed;

	spin_lock_irqsave(&ec->lock, flags);
	flushed = acpi_ec_flushed(ec);
	spin_unlock_irqrestore(&ec->lock, flags);
	return flushed;
}

static void acpi_ec_stop(struct acpi_ec *ec, bool suspending)
{
	unsigned long flags;

	spin_lock_irqsave(&ec->lock, flags);
	if (acpi_ec_started(ec)) {
		ec_dbg_drv("Stopping EC");
		set_bit(EC_FLAGS_STOPPED, &ec->flags);
		spin_unlock_irqrestore(&ec->lock, flags);
		wait_event(ec->wait, acpi_ec_stopped(ec));
		spin_lock_irqsave(&ec->lock, flags);
		/* Disable GPE for event processing (SCI_EVT=1) */
		if (!suspending) {
			acpi_ec_complete_request(ec);
			ec_dbg_ref(ec, "Decrease driver");
		}
		clear_bit(EC_FLAGS_STARTED, &ec->flags);
		clear_bit(EC_FLAGS_STOPPED, &ec->flags);
		ec_log_drv("EC stopped");
	}
	spin_unlock_irqrestore(&ec->lock, flags);
}

void acpi_ec_block_transactions(void)
{
	struct acpi_ec *ec = first_ec;

	if (!ec)
		return;

	mutex_lock(&ec->mutex);
	/* Prevent transactions from being carried out */
	acpi_ec_stop(ec, true);
	mutex_unlock(&ec->mutex);
}

void acpi_ec_unblock_transactions(void)
{
	struct acpi_ec *ec = first_ec;

	if (!ec)
		return;

	/* Allow transactions to be carried out again */
	acpi_ec_start(ec, true);

	if (EC_FLAGS_CLEAR_ON_RESUME)
		acpi_ec_clear(ec);
}

void acpi_ec_unblock_transactions_early(void)
{
	/*
	 * Allow transactions to happen again (this function is called from
	 * atomic context during wakeup, so we don't need to acquire the mutex).
	 */
	if (first_ec)
		acpi_ec_start(first_ec, true);
}

/* --------------------------------------------------------------------------
                                Event Management
   -------------------------------------------------------------------------- */
static struct acpi_ec_query_handler *
acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler)
{
	if (handler)
		kref_get(&handler->kref);
	return handler;
}

static struct acpi_ec_query_handler *
acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value)
{
	struct acpi_ec_query_handler *handler;
	bool found = false;

	mutex_lock(&ec->mutex);
	list_for_each_entry(handler, &ec->list, node) {
		if (value == handler->query_bit) {
			found = true;
			break;
		}
	}
	mutex_unlock(&ec->mutex);
	return found ? acpi_ec_get_query_handler(handler) : NULL;
}

static void acpi_ec_query_handler_release(struct kref *kref)
{
	struct acpi_ec_query_handler *handler =
		container_of(kref, struct acpi_ec_query_handler, kref);

	kfree(handler);
}

static void acpi_ec_put_query_handler(struct acpi_ec_query_handler *handler)
{
	kref_put(&handler->kref, acpi_ec_query_handler_release);
}

int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
			      acpi_handle handle, acpi_ec_query_func func,
			      void *data)
{
	struct acpi_ec_query_handler *handler =
	    kzalloc(sizeof(struct acpi_ec_query_handler), GFP_KERNEL);

	if (!handler)
		return -ENOMEM;

	handler->query_bit = query_bit;
	handler->handle = handle;
	handler->func = func;
	handler->data = data;
	mutex_lock(&ec->mutex);
	kref_init(&handler->kref);
	list_add(&handler->node, &ec->list);
	mutex_unlock(&ec->mutex);
	return 0;
}
EXPORT_SYMBOL_GPL(acpi_ec_add_query_handler);

static void acpi_ec_remove_query_handlers(struct acpi_ec *ec,
					  bool remove_all, u8 query_bit)
{
	struct acpi_ec_query_handler *handler, *tmp;
	LIST_HEAD(free_list);

	mutex_lock(&ec->mutex);
	list_for_each_entry_safe(handler, tmp, &ec->list, node) {
		if (remove_all || query_bit == handler->query_bit) {
			list_del_init(&handler->node);
			list_add(&handler->node, &free_list);
		}
	}
	mutex_unlock(&ec->mutex);
	list_for_each_entry_safe(handler, tmp, &free_list, node)
		acpi_ec_put_query_handler(handler);
}

void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
{
	acpi_ec_remove_query_handlers(ec, false, query_bit);
}
EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);

static struct acpi_ec_query *acpi_ec_create_query(u8 *pval)
{
	struct acpi_ec_query *q;
	struct transaction *t;

	q = kzalloc(sizeof (struct acpi_ec_query), GFP_KERNEL);
	if (!q)
		return NULL;
	INIT_WORK(&q->work, acpi_ec_event_processor);
	t = &q->transaction;
	t->command = ACPI_EC_COMMAND_QUERY;
	t->rdata = pval;
	t->rlen = 1;
	return q;
}

static void acpi_ec_delete_query(struct acpi_ec_query *q)
{
	if (q) {
		if (q->handler)
			acpi_ec_put_query_handler(q->handler);
		kfree(q);
	}
}

static void acpi_ec_event_processor(struct work_struct *work)
{
	struct acpi_ec_query *q = container_of(work, struct acpi_ec_query, work);
	struct acpi_ec_query_handler *handler = q->handler;

	ec_dbg_evt("Query(0x%02x) started", handler->query_bit);
	if (handler->func)
		handler->func(handler->data);
	else if (handler->handle)
		acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
	ec_dbg_evt("Query(0x%02x) stopped", handler->query_bit);
	acpi_ec_delete_query(q);
}

static int acpi_ec_query(struct acpi_ec *ec, u8 *data)
{
	u8 value = 0;
	int result;
	struct acpi_ec_query *q;

	q = acpi_ec_create_query(&value);
	if (!q)
		return -ENOMEM;

	/*
	 * Query the EC to find out which _Qxx method we need to evaluate.
	 * Note that successful completion of the query causes the ACPI_EC_SCI
	 * bit to be cleared (and thus clearing the interrupt source).
	 */
	result = acpi_ec_transaction(ec, &q->transaction);
	if (!value)
		result = -ENODATA;
	if (result)
		goto err_exit;

	q->handler = acpi_ec_get_query_handler_by_value(ec, value);
	if (!q->handler) {
		result = -ENODATA;
		goto err_exit;
	}

	/*
	 * It is reported that _Qxx are evaluated in a parallel way on
	 * Windows:
	 * https://bugzilla.kernel.org/show_bug.cgi?id=94411
	 *
	 * Put this log entry before schedule_work() in order to make
	 * it appearing before any other log entries occurred during the
	 * work queue execution.
	 */
	ec_dbg_evt("Query(0x%02x) scheduled", value);
	if (!schedule_work(&q->work)) {
		ec_dbg_evt("Query(0x%02x) overlapped", value);
		result = -EBUSY;
	}

err_exit:
	if (result)
		acpi_ec_delete_query(q);
	if (data)
		*data = value;
	return result;
}

static void acpi_ec_check_event(struct acpi_ec *ec)
{
	unsigned long flags;

	if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT) {
		if (ec_guard(ec)) {
			spin_lock_irqsave(&ec->lock, flags);
			/*
			 * Take care of the SCI_EVT unless no one else is
			 * taking care of it.
			 */
			if (!ec->curr)
				advance_transaction(ec);
			spin_unlock_irqrestore(&ec->lock, flags);
		}
	}
}

static void acpi_ec_event_handler(struct work_struct *work)
{
	unsigned long flags;
	struct acpi_ec *ec = container_of(work, struct acpi_ec, work);

	ec_dbg_evt("Event started");

	spin_lock_irqsave(&ec->lock, flags);
	while (ec->nr_pending_queries) {
		spin_unlock_irqrestore(&ec->lock, flags);
		(void)acpi_ec_query(ec, NULL);
		spin_lock_irqsave(&ec->lock, flags);
		ec->nr_pending_queries--;
		/*
		 * Before exit, make sure that this work item can be
		 * scheduled again. There might be QR_EC failures, leaving
		 * EC_FLAGS_QUERY_PENDING uncleared and preventing this work
		 * item from being scheduled again.
		 */
		if (!ec->nr_pending_queries) {
			if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
			    ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY)
				acpi_ec_complete_query(ec);
		}
	}
	spin_unlock_irqrestore(&ec->lock, flags);

	ec_dbg_evt("Event stopped");

	acpi_ec_check_event(ec);
}

static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
	u32 gpe_number, void *data)
{
	unsigned long flags;
	struct acpi_ec *ec = data;

	spin_lock_irqsave(&ec->lock, flags);
	advance_transaction(ec);
	spin_unlock_irqrestore(&ec->lock, flags);
	return ACPI_INTERRUPT_HANDLED;
}

/* --------------------------------------------------------------------------
 *                           Address Space Management
 * -------------------------------------------------------------------------- */

static acpi_status
acpi_ec_space_handler(u32 function, acpi_physical_address address,
		      u32 bits, u64 *value64,
		      void *handler_context, void *region_context)
{
	struct acpi_ec *ec = handler_context;
	int result = 0, i, bytes = bits / 8;
	u8 *value = (u8 *)value64;

	if ((address > 0xFF) || !value || !handler_context)
		return AE_BAD_PARAMETER;

	if (function != ACPI_READ && function != ACPI_WRITE)
		return AE_BAD_PARAMETER;

	if (ec_busy_polling || bits > 8)
		acpi_ec_burst_enable(ec);

	for (i = 0; i < bytes; ++i, ++address, ++value)
		result = (function == ACPI_READ) ?
			acpi_ec_read(ec, address, value) :
			acpi_ec_write(ec, address, *value);

	if (ec_busy_polling || bits > 8)
		acpi_ec_burst_disable(ec);

	switch (result) {
	case -EINVAL:
		return AE_BAD_PARAMETER;
	case -ENODEV:
		return AE_NOT_FOUND;
	case -ETIME:
		return AE_TIME;
	default:
		return AE_OK;
	}
}

/* --------------------------------------------------------------------------
 *                             Driver Interface
 * -------------------------------------------------------------------------- */

static acpi_status
ec_parse_io_ports(struct acpi_resource *resource, void *context);

static struct acpi_ec *make_acpi_ec(void)
{
	struct acpi_ec *ec = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);

	if (!ec)
		return NULL;
	ec->flags = 1 << EC_FLAGS_QUERY_PENDING;
	mutex_init(&ec->mutex);
	init_waitqueue_head(&ec->wait);
	INIT_LIST_HEAD(&ec->list);
	spin_lock_init(&ec->lock);
	INIT_WORK(&ec->work, acpi_ec_event_handler);
	ec->timestamp = jiffies;
	return ec;
}

static acpi_status
acpi_ec_register_query_methods(acpi_handle handle, u32 level,
			       void *context, void **return_value)
{
	char node_name[5];
	struct acpi_buffer buffer = { sizeof(node_name), node_name };
	struct acpi_ec *ec = context;
	int value = 0;
	acpi_status status;

	status = acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);

	if (ACPI_SUCCESS(status) && sscanf(node_name, "_Q%x", &value) == 1)
		acpi_ec_add_query_handler(ec, value, handle, NULL, NULL);
	return AE_OK;
}

static acpi_status
ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
{
	acpi_status status;
	unsigned long long tmp = 0;
	struct acpi_ec *ec = context;

	/* clear addr values, ec_parse_io_ports depend on it */
	ec->command_addr = ec->data_addr = 0;

	status = acpi_walk_resources(handle, METHOD_NAME__CRS,
				     ec_parse_io_ports, ec);
	if (ACPI_FAILURE(status))
		return status;

	/* Get GPE bit assignment (EC events). */
	/* TODO: Add support for _GPE returning a package */
	status = acpi_evaluate_integer(handle, "_GPE", NULL, &tmp);
	if (ACPI_FAILURE(status))
		return status;
	ec->gpe = tmp;
	/* Use the global lock for all EC transactions? */
	tmp = 0;
	acpi_evaluate_integer(handle, "_GLK", NULL, &tmp);
	ec->global_lock = tmp;
	ec->handle = handle;
	return AE_CTRL_TERMINATE;
}

static int ec_install_handlers(struct acpi_ec *ec)
{
	acpi_status status;

	acpi_ec_start(ec, false);

	if (!test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
		status = acpi_install_address_space_handler(ec->handle,
							    ACPI_ADR_SPACE_EC,
							    &acpi_ec_space_handler,
							    NULL, ec);
		if (ACPI_FAILURE(status)) {
			if (status == AE_NOT_FOUND) {
				/*
				 * Maybe OS fails in evaluating the _REG
				 * object. The AE_NOT_FOUND error will be
				 * ignored and OS * continue to initialize
				 * EC.
				 */
				pr_err("Fail in evaluating the _REG object"
					" of EC device. Broken bios is suspected.\n");
			} else {
				acpi_ec_stop(ec, false);
				return -ENODEV;
			}
		}
		set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
	}

	if (!test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
		status = acpi_install_gpe_raw_handler(NULL, ec->gpe,
					  ACPI_GPE_EDGE_TRIGGERED,
					  &acpi_ec_gpe_handler, ec);
		/* This is not fatal as we can poll EC events */
		if (ACPI_SUCCESS(status)) {
			set_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags);
			if (test_bit(EC_FLAGS_STARTED, &ec->flags) &&
			    ec->reference_count >= 1)
				acpi_ec_enable_gpe(ec, true);
		}
	}

	return 0;
}

static void ec_remove_handlers(struct acpi_ec *ec)
{
	acpi_ec_stop(ec, false);

	if (test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
		if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
					ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
			pr_err("failed to remove space handler\n");
		clear_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
	}

	if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
		if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
					&acpi_ec_gpe_handler)))
			pr_err("failed to remove gpe handler\n");
		clear_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags);
	}
}

static int acpi_ec_add(struct acpi_device *device)
{
	struct acpi_ec *ec = NULL;
	int ret;

	strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
	strcpy(acpi_device_class(device), ACPI_EC_CLASS);

	/* Check for boot EC */
	if (boot_ec) {
		ec = boot_ec;
		boot_ec = NULL;
		ec_remove_handlers(ec);
		if (first_ec == ec)
			first_ec = NULL;
	} else {
		ec = make_acpi_ec();
		if (!ec)
			return -ENOMEM;
	}
	if (ec_parse_device(device->handle, 0, ec, NULL) !=
		AE_CTRL_TERMINATE) {
			kfree(ec);
			return -EINVAL;
	}

	/* Find and register all query methods */
	acpi_walk_namespace(ACPI_TYPE_METHOD, ec->handle, 1,
			    acpi_ec_register_query_methods, NULL, ec, NULL);

	if (!first_ec)
		first_ec = ec;
	device->driver_data = ec;

	ret = !!request_region(ec->data_addr, 1, "EC data");
	WARN(!ret, "Could not request EC data io port 0x%lx", ec->data_addr);
	ret = !!request_region(ec->command_addr, 1, "EC cmd");
	WARN(!ret, "Could not request EC cmd io port 0x%lx", ec->command_addr);

	pr_info("GPE = 0x%lx, I/O: command/status = 0x%lx, data = 0x%lx\n",
			  ec->gpe, ec->command_addr, ec->data_addr);

	ret = ec_install_handlers(ec);

	/* Reprobe devices depending on the EC */
	acpi_walk_dep_device_list(ec->handle);

	/* EC is fully operational, allow queries */
	clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);

	/* Clear stale _Q events if hardware might require that */
	if (EC_FLAGS_CLEAR_ON_RESUME)
		acpi_ec_clear(ec);
	return ret;
}

static int acpi_ec_remove(struct acpi_device *device)
{
	struct acpi_ec *ec;

	if (!device)
		return -EINVAL;

	ec = acpi_driver_data(device);
	ec_remove_handlers(ec);
	acpi_ec_remove_query_handlers(ec, true, 0);
	release_region(ec->data_addr, 1);
	release_region(ec->command_addr, 1);
	device->driver_data = NULL;
	if (ec == first_ec)
		first_ec = NULL;
	kfree(ec);
	return 0;
}

static acpi_status
ec_parse_io_ports(struct acpi_resource *resource, void *context)
{
	struct acpi_ec *ec = context;

	if (resource->type != ACPI_RESOURCE_TYPE_IO)
		return AE_OK;

	/*
	 * The first address region returned is the data port, and
	 * the second address region returned is the status/command
	 * port.
	 */
	if (ec->data_addr == 0)
		ec->data_addr = resource->data.io.minimum;
	else if (ec->command_addr == 0)
		ec->command_addr = resource->data.io.minimum;
	else
		return AE_CTRL_TERMINATE;

	return AE_OK;
}

static const struct acpi_device_id ec_device_ids[] = {
	{"PNP0C09", 0},
	{"", 0},
};

int __init acpi_ec_dsdt_probe(void)
{
	acpi_status status;

	if (boot_ec)
		return 0;

	/*
	 * Finding EC from DSDT if there is no ECDT EC available. When this
	 * function is invoked, ACPI tables have been fully loaded, we can
	 * walk namespace now.
	 */
	boot_ec = make_acpi_ec();
	if (!boot_ec)
		return -ENOMEM;
	status = acpi_get_devices(ec_device_ids[0].id,
				  ec_parse_device, boot_ec, NULL);
	if (ACPI_FAILURE(status) || !boot_ec->handle)
		return -ENODEV;
	if (!ec_install_handlers(boot_ec)) {
		first_ec = boot_ec;
		return 0;
	}
	return -EFAULT;
}

#if 0
/*
 * Some EC firmware variations refuses to respond QR_EC when SCI_EVT is not
 * set, for which case, we complete the QR_EC without issuing it to the
 * firmware.
 * https://bugzilla.kernel.org/show_bug.cgi?id=82611
 * https://bugzilla.kernel.org/show_bug.cgi?id=97381
 */
static int ec_flag_query_handshake(const struct dmi_system_id *id)
{
	pr_debug("Detected the EC firmware requiring QR_EC issued when SCI_EVT set\n");
	EC_FLAGS_QUERY_HANDSHAKE = 1;
	return 0;
}
#endif

/*
 * On some hardware it is necessary to clear events accumulated by the EC during
 * sleep. These ECs stop reporting GPEs until they are manually polled, if too
 * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
 *
 * https://bugzilla.kernel.org/show_bug.cgi?id=44161
 *
 * Ideally, the EC should also be instructed NOT to accumulate events during
 * sleep (which Windows seems to do somehow), but the interface to control this
 * behaviour is not known at this time.
 *
 * Models known to be affected are Samsung 530Uxx/535Uxx/540Uxx/550Pxx/900Xxx,
 * however it is very likely that other Samsung models are affected.
 *
 * On systems which don't accumulate _Q events during sleep, this extra check
 * should be harmless.
 */
static int ec_clear_on_resume(const struct dmi_system_id *id)
{
	pr_debug("Detected system needing EC poll on resume.\n");
	EC_FLAGS_CLEAR_ON_RESUME = 1;
	ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS;
	return 0;
}

static int ec_correct_ecdt(const struct dmi_system_id *id)
{
	pr_debug("Detected system needing ECDT address correction.\n");
	EC_FLAGS_CORRECT_ECDT = 1;
	return 0;
}

static struct dmi_system_id ec_dmi_table[] __initdata = {
	{
	ec_correct_ecdt, "Asus L4R", {
	DMI_MATCH(DMI_BIOS_VERSION, "1008.006"),
	DMI_MATCH(DMI_PRODUCT_NAME, "L4R"),
	DMI_MATCH(DMI_BOARD_NAME, "L4R") }, NULL},
	{
	ec_correct_ecdt, "Asus M6R", {
	DMI_MATCH(DMI_BIOS_VERSION, "0207"),
	DMI_MATCH(DMI_PRODUCT_NAME, "M6R"),
	DMI_MATCH(DMI_BOARD_NAME, "M6R") }, NULL},
	{
	ec_correct_ecdt, "MSI MS-171F", {
	DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star"),
	DMI_MATCH(DMI_PRODUCT_NAME, "MS-171F"),}, NULL},
	{
	ec_clear_on_resume, "Samsung hardware", {
	DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
	{},
};

int __init acpi_ec_ecdt_probe(void)
{
	int ret = 0;
	acpi_status status;
	struct acpi_table_ecdt *ecdt_ptr;

	boot_ec = make_acpi_ec();
	if (!boot_ec)
		return -ENOMEM;
	/*
	 * Generate a boot ec context
	 */
	dmi_check_system(ec_dmi_table);
	status = acpi_get_table(ACPI_SIG_ECDT, 1,
				(struct acpi_table_header **)&ecdt_ptr);
	if (ACPI_FAILURE(status)) {
		ret = -ENODEV;
		goto error;
	}

	if (!ecdt_ptr->control.address || !ecdt_ptr->data.address) {
		/*
		 * Asus X50GL:
		 * https://bugzilla.kernel.org/show_bug.cgi?id=11880
		 */
		ret = -ENODEV;
		goto error;
	}

	pr_info("EC description table is found, configuring boot EC\n");
	if (EC_FLAGS_CORRECT_ECDT) {
		/*
		 * Asus L4R, Asus M6R
		 * https://bugzilla.kernel.org/show_bug.cgi?id=9399
		 * MSI MS-171F
		 * https://bugzilla.kernel.org/show_bug.cgi?id=12461
		 */
		boot_ec->command_addr = ecdt_ptr->data.address;
		boot_ec->data_addr = ecdt_ptr->control.address;
	} else {
		boot_ec->command_addr = ecdt_ptr->control.address;
		boot_ec->data_addr = ecdt_ptr->data.address;
	}
	boot_ec->gpe = ecdt_ptr->gpe;
	boot_ec->handle = ACPI_ROOT_OBJECT;
	ret = ec_install_handlers(boot_ec);
	if (!ret)
		first_ec = boot_ec;
error:
	if (ret) {
		kfree(boot_ec);
		boot_ec = NULL;
	}
	return ret;
}

static int param_set_event_clearing(const char *val, struct kernel_param *kp)
{
	int result = 0;

	if (!strncmp(val, "status", sizeof("status") - 1)) {
		ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS;
		pr_info("Assuming SCI_EVT clearing on EC_SC accesses\n");
	} else if (!strncmp(val, "query", sizeof("query") - 1)) {
		ec_event_clearing = ACPI_EC_EVT_TIMING_QUERY;
		pr_info("Assuming SCI_EVT clearing on QR_EC writes\n");
	} else if (!strncmp(val, "event", sizeof("event") - 1)) {
		ec_event_clearing = ACPI_EC_EVT_TIMING_EVENT;
		pr_info("Assuming SCI_EVT clearing on event reads\n");
	} else
		result = -EINVAL;
	return result;
}

static int param_get_event_clearing(char *buffer, struct kernel_param *kp)
{
	switch (ec_event_clearing) {
	case ACPI_EC_EVT_TIMING_STATUS:
		return sprintf(buffer, "status");
	case ACPI_EC_EVT_TIMING_QUERY:
		return sprintf(buffer, "query");
	case ACPI_EC_EVT_TIMING_EVENT:
		return sprintf(buffer, "event");
	default:
		return sprintf(buffer, "invalid");
	}
	return 0;
}

module_param_call(ec_event_clearing, param_set_event_clearing, param_get_event_clearing,
		  NULL, 0644);
MODULE_PARM_DESC(ec_event_clearing, "Assumed SCI_EVT clearing timing");

static struct acpi_driver acpi_ec_driver = {
	.name = "ec",
	.class = ACPI_EC_CLASS,
	.ids = ec_device_ids,
	.ops = {
		.add = acpi_ec_add,
		.remove = acpi_ec_remove,
		},
};

int __init acpi_ec_init(void)
{
	int result = 0;

	/* Now register the driver for the EC */
	result = acpi_bus_register_driver(&acpi_ec_driver);
	if (result < 0)
		return -ENODEV;

	return result;
}

/* EC driver currently not unloadable */
#if 0
static void __exit acpi_ec_exit(void)
{

	acpi_bus_unregister_driver(&acpi_ec_driver);
}
#endif	/* 0 */