summaryrefslogtreecommitdiffstats
path: root/drivers/tty/serial/serial-tegra.c
blob: 1d5ea3964ee59d61d882ad23e35f63e367e86af5 (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
/*
 * serial_tegra.c
 *
 * High-speed serial driver for NVIDIA Tegra SoCs
 *
 * Copyright (c) 2012-2013, NVIDIA CORPORATION.  All rights reserved.
 *
 * Author: Laxman Dewangan <ldewangan@nvidia.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pagemap.h>
#include <linux/platform_device.h>
#include <linux/reset.h>
#include <linux/serial.h>
#include <linux/serial_8250.h>
#include <linux/serial_core.h>
#include <linux/serial_reg.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/termios.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>

#define TEGRA_UART_TYPE				"TEGRA_UART"
#define TX_EMPTY_STATUS				(UART_LSR_TEMT | UART_LSR_THRE)
#define BYTES_TO_ALIGN(x)			((unsigned long)(x) & 0x3)

#define TEGRA_UART_RX_DMA_BUFFER_SIZE		4096
#define TEGRA_UART_LSR_TXFIFO_FULL		0x100
#define TEGRA_UART_IER_EORD			0x20
#define TEGRA_UART_MCR_RTS_EN			0x40
#define TEGRA_UART_MCR_CTS_EN			0x20
#define TEGRA_UART_LSR_ANY			(UART_LSR_OE | UART_LSR_BI | \
						UART_LSR_PE | UART_LSR_FE)
#define TEGRA_UART_IRDA_CSR			0x08
#define TEGRA_UART_SIR_ENABLED			0x80

#define TEGRA_UART_TX_PIO			1
#define TEGRA_UART_TX_DMA			2
#define TEGRA_UART_MIN_DMA			16
#define TEGRA_UART_FIFO_SIZE			32

/*
 * Tx fifo trigger level setting in tegra uart is in
 * reverse way then conventional uart.
 */
#define TEGRA_UART_TX_TRIG_16B			0x00
#define TEGRA_UART_TX_TRIG_8B			0x10
#define TEGRA_UART_TX_TRIG_4B			0x20
#define TEGRA_UART_TX_TRIG_1B			0x30

#define TEGRA_UART_MAXIMUM			5

/* Default UART setting when started: 115200 no parity, stop, 8 data bits */
#define TEGRA_UART_DEFAULT_BAUD			115200
#define TEGRA_UART_DEFAULT_LSR			UART_LCR_WLEN8

/* Tx transfer mode */
#define TEGRA_TX_PIO				1
#define TEGRA_TX_DMA				2

/**
 * tegra_uart_chip_data: SOC specific data.
 *
 * @tx_fifo_full_status: Status flag available for checking tx fifo full.
 * @allow_txfifo_reset_fifo_mode: allow_tx fifo reset with fifo mode or not.
 *			Tegra30 does not allow this.
 * @support_clk_src_div: Clock source support the clock divider.
 */
struct tegra_uart_chip_data {
	bool	tx_fifo_full_status;
	bool	allow_txfifo_reset_fifo_mode;
	bool	support_clk_src_div;
};

struct tegra_uart_port {
	struct uart_port			uport;
	const struct tegra_uart_chip_data	*cdata;

	struct clk				*uart_clk;
	struct reset_control			*rst;
	unsigned int				current_baud;

	/* Register shadow */
	unsigned long				fcr_shadow;
	unsigned long				mcr_shadow;
	unsigned long				lcr_shadow;
	unsigned long				ier_shadow;
	bool					rts_active;

	int					tx_in_progress;
	unsigned int				tx_bytes;

	bool					enable_modem_interrupt;

	bool					rx_timeout;
	int					rx_in_progress;
	int					symb_bit;

	struct dma_chan				*rx_dma_chan;
	struct dma_chan				*tx_dma_chan;
	dma_addr_t				rx_dma_buf_phys;
	dma_addr_t				tx_dma_buf_phys;
	unsigned char				*rx_dma_buf_virt;
	unsigned char				*tx_dma_buf_virt;
	struct dma_async_tx_descriptor		*tx_dma_desc;
	struct dma_async_tx_descriptor		*rx_dma_desc;
	dma_cookie_t				tx_cookie;
	dma_cookie_t				rx_cookie;
	int					tx_bytes_requested;
	int					rx_bytes_requested;
};

static void tegra_uart_start_next_tx(struct tegra_uart_port *tup);
static int tegra_uart_start_rx_dma(struct tegra_uart_port *tup);

static inline unsigned long tegra_uart_read(struct tegra_uart_port *tup,
		unsigned long reg)
{
	return readl(tup->uport.membase + (reg << tup->uport.regshift));
}

static inline void tegra_uart_write(struct tegra_uart_port *tup, unsigned val,
	unsigned long reg)
{
	writel(val, tup->uport.membase + (reg << tup->uport.regshift));
}

static inline struct tegra_uart_port *to_tegra_uport(struct uart_port *u)
{
	return container_of(u, struct tegra_uart_port, uport);
}

static unsigned int tegra_uart_get_mctrl(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);

	/*
	 * RI - Ring detector is active
	 * CD/DCD/CAR - Carrier detect is always active. For some reason
	 *	linux has different names for carrier detect.
	 * DSR - Data Set ready is active as the hardware doesn't support it.
	 *	Don't know if the linux support this yet?
	 * CTS - Clear to send. Always set to active, as the hardware handles
	 *	CTS automatically.
	 */
	if (tup->enable_modem_interrupt)
		return TIOCM_RI | TIOCM_CD | TIOCM_DSR | TIOCM_CTS;
	return TIOCM_CTS;
}

static void set_rts(struct tegra_uart_port *tup, bool active)
{
	unsigned long mcr;

	mcr = tup->mcr_shadow;
	if (active)
		mcr |= TEGRA_UART_MCR_RTS_EN;
	else
		mcr &= ~TEGRA_UART_MCR_RTS_EN;
	if (mcr != tup->mcr_shadow) {
		tegra_uart_write(tup, mcr, UART_MCR);
		tup->mcr_shadow = mcr;
	}
	return;
}

static void set_dtr(struct tegra_uart_port *tup, bool active)
{
	unsigned long mcr;

	mcr = tup->mcr_shadow;
	if (active)
		mcr |= UART_MCR_DTR;
	else
		mcr &= ~UART_MCR_DTR;
	if (mcr != tup->mcr_shadow) {
		tegra_uart_write(tup, mcr, UART_MCR);
		tup->mcr_shadow = mcr;
	}
	return;
}

static void tegra_uart_set_mctrl(struct uart_port *u, unsigned int mctrl)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	unsigned long mcr;
	int dtr_enable;

	mcr = tup->mcr_shadow;
	tup->rts_active = !!(mctrl & TIOCM_RTS);
	set_rts(tup, tup->rts_active);

	dtr_enable = !!(mctrl & TIOCM_DTR);
	set_dtr(tup, dtr_enable);
	return;
}

static void tegra_uart_break_ctl(struct uart_port *u, int break_ctl)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	unsigned long lcr;

	lcr = tup->lcr_shadow;
	if (break_ctl)
		lcr |= UART_LCR_SBC;
	else
		lcr &= ~UART_LCR_SBC;
	tegra_uart_write(tup, lcr, UART_LCR);
	tup->lcr_shadow = lcr;
}

/* Wait for a symbol-time. */
static void tegra_uart_wait_sym_time(struct tegra_uart_port *tup,
		unsigned int syms)
{
	if (tup->current_baud)
		udelay(DIV_ROUND_UP(syms * tup->symb_bit * 1000000,
			tup->current_baud));
}

static void tegra_uart_fifo_reset(struct tegra_uart_port *tup, u8 fcr_bits)
{
	unsigned long fcr = tup->fcr_shadow;

	if (tup->cdata->allow_txfifo_reset_fifo_mode) {
		fcr |= fcr_bits & (UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
		tegra_uart_write(tup, fcr, UART_FCR);
	} else {
		fcr &= ~UART_FCR_ENABLE_FIFO;
		tegra_uart_write(tup, fcr, UART_FCR);
		udelay(60);
		fcr |= fcr_bits & (UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
		tegra_uart_write(tup, fcr, UART_FCR);
		fcr |= UART_FCR_ENABLE_FIFO;
		tegra_uart_write(tup, fcr, UART_FCR);
	}

	/* Dummy read to ensure the write is posted */
	tegra_uart_read(tup, UART_SCR);

	/* Wait for the flush to propagate. */
	tegra_uart_wait_sym_time(tup, 1);
}

static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
{
	unsigned long rate;
	unsigned int divisor;
	unsigned long lcr;
	int ret;

	if (tup->current_baud == baud)
		return 0;

	if (tup->cdata->support_clk_src_div) {
		rate = baud * 16;
		ret = clk_set_rate(tup->uart_clk, rate);
		if (ret < 0) {
			dev_err(tup->uport.dev,
				"clk_set_rate() failed for rate %lu\n", rate);
			return ret;
		}
		divisor = 1;
	} else {
		rate = clk_get_rate(tup->uart_clk);
		divisor = DIV_ROUND_CLOSEST(rate, baud * 16);
	}

	lcr = tup->lcr_shadow;
	lcr |= UART_LCR_DLAB;
	tegra_uart_write(tup, lcr, UART_LCR);

	tegra_uart_write(tup, divisor & 0xFF, UART_TX);
	tegra_uart_write(tup, ((divisor >> 8) & 0xFF), UART_IER);

	lcr &= ~UART_LCR_DLAB;
	tegra_uart_write(tup, lcr, UART_LCR);

	/* Dummy read to ensure the write is posted */
	tegra_uart_read(tup, UART_SCR);

	tup->current_baud = baud;

	/* wait two character intervals at new rate */
	tegra_uart_wait_sym_time(tup, 2);
	return 0;
}

static char tegra_uart_decode_rx_error(struct tegra_uart_port *tup,
			unsigned long lsr)
{
	char flag = TTY_NORMAL;

	if (unlikely(lsr & TEGRA_UART_LSR_ANY)) {
		if (lsr & UART_LSR_OE) {
			/* Overrrun error */
			flag = TTY_OVERRUN;
			tup->uport.icount.overrun++;
			dev_err(tup->uport.dev, "Got overrun errors\n");
		} else if (lsr & UART_LSR_PE) {
			/* Parity error */
			flag = TTY_PARITY;
			tup->uport.icount.parity++;
			dev_err(tup->uport.dev, "Got Parity errors\n");
		} else if (lsr & UART_LSR_FE) {
			flag = TTY_FRAME;
			tup->uport.icount.frame++;
			dev_err(tup->uport.dev, "Got frame errors\n");
		} else if (lsr & UART_LSR_BI) {
			dev_err(tup->uport.dev, "Got Break\n");
			tup->uport.icount.brk++;
			/* If FIFO read error without any data, reset Rx FIFO */
			if (!(lsr & UART_LSR_DR) && (lsr & UART_LSR_FIFOE))
				tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_RCVR);
		}
	}
	return flag;
}

static int tegra_uart_request_port(struct uart_port *u)
{
	return 0;
}

static void tegra_uart_release_port(struct uart_port *u)
{
	/* Nothing to do here */
}

static void tegra_uart_fill_tx_fifo(struct tegra_uart_port *tup, int max_bytes)
{
	struct circ_buf *xmit = &tup->uport.state->xmit;
	int i;

	for (i = 0; i < max_bytes; i++) {
		BUG_ON(uart_circ_empty(xmit));
		if (tup->cdata->tx_fifo_full_status) {
			unsigned long lsr = tegra_uart_read(tup, UART_LSR);
			if ((lsr & TEGRA_UART_LSR_TXFIFO_FULL))
				break;
		}
		tegra_uart_write(tup, xmit->buf[xmit->tail], UART_TX);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		tup->uport.icount.tx++;
	}
}

static void tegra_uart_start_pio_tx(struct tegra_uart_port *tup,
		unsigned int bytes)
{
	if (bytes > TEGRA_UART_MIN_DMA)
		bytes = TEGRA_UART_MIN_DMA;

	tup->tx_in_progress = TEGRA_UART_TX_PIO;
	tup->tx_bytes = bytes;
	tup->ier_shadow |= UART_IER_THRI;
	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
}

static void tegra_uart_tx_dma_complete(void *args)
{
	struct tegra_uart_port *tup = args;
	struct circ_buf *xmit = &tup->uport.state->xmit;
	struct dma_tx_state state;
	unsigned long flags;
	int count;

	dmaengine_tx_status(tup->tx_dma_chan, tup->rx_cookie, &state);
	count = tup->tx_bytes_requested - state.residue;
	async_tx_ack(tup->tx_dma_desc);
	spin_lock_irqsave(&tup->uport.lock, flags);
	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
	tup->tx_in_progress = 0;
	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(&tup->uport);
	tegra_uart_start_next_tx(tup);
	spin_unlock_irqrestore(&tup->uport.lock, flags);
}

static int tegra_uart_start_tx_dma(struct tegra_uart_port *tup,
		unsigned long count)
{
	struct circ_buf *xmit = &tup->uport.state->xmit;
	dma_addr_t tx_phys_addr;

	dma_sync_single_for_device(tup->uport.dev, tup->tx_dma_buf_phys,
				UART_XMIT_SIZE, DMA_TO_DEVICE);

	tup->tx_bytes = count & ~(0xF);
	tx_phys_addr = tup->tx_dma_buf_phys + xmit->tail;
	tup->tx_dma_desc = dmaengine_prep_slave_single(tup->tx_dma_chan,
				tx_phys_addr, tup->tx_bytes, DMA_MEM_TO_DEV,
				DMA_PREP_INTERRUPT);
	if (!tup->tx_dma_desc) {
		dev_err(tup->uport.dev, "Not able to get desc for Tx\n");
		return -EIO;
	}

	tup->tx_dma_desc->callback = tegra_uart_tx_dma_complete;
	tup->tx_dma_desc->callback_param = tup;
	tup->tx_in_progress = TEGRA_UART_TX_DMA;
	tup->tx_bytes_requested = tup->tx_bytes;
	tup->tx_cookie = dmaengine_submit(tup->tx_dma_desc);
	dma_async_issue_pending(tup->tx_dma_chan);
	return 0;
}

static void tegra_uart_start_next_tx(struct tegra_uart_port *tup)
{
	unsigned long tail;
	unsigned long count;
	struct circ_buf *xmit = &tup->uport.state->xmit;

	tail = (unsigned long)&xmit->buf[xmit->tail];
	count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
	if (!count)
		return;

	if (count < TEGRA_UART_MIN_DMA)
		tegra_uart_start_pio_tx(tup, count);
	else if (BYTES_TO_ALIGN(tail) > 0)
		tegra_uart_start_pio_tx(tup, BYTES_TO_ALIGN(tail));
	else
		tegra_uart_start_tx_dma(tup, count);
}

/* Called by serial core driver with u->lock taken. */
static void tegra_uart_start_tx(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	struct circ_buf *xmit = &u->state->xmit;

	if (!uart_circ_empty(xmit) && !tup->tx_in_progress)
		tegra_uart_start_next_tx(tup);
}

static unsigned int tegra_uart_tx_empty(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	unsigned int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&u->lock, flags);
	if (!tup->tx_in_progress) {
		unsigned long lsr = tegra_uart_read(tup, UART_LSR);
		if ((lsr & TX_EMPTY_STATUS) == TX_EMPTY_STATUS)
			ret = TIOCSER_TEMT;
	}
	spin_unlock_irqrestore(&u->lock, flags);
	return ret;
}

static void tegra_uart_stop_tx(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	struct circ_buf *xmit = &tup->uport.state->xmit;
	struct dma_tx_state state;
	int count;

	if (tup->tx_in_progress != TEGRA_UART_TX_DMA)
		return;

	dmaengine_terminate_all(tup->tx_dma_chan);
	dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
	count = tup->tx_bytes_requested - state.residue;
	async_tx_ack(tup->tx_dma_desc);
	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
	tup->tx_in_progress = 0;
	return;
}

static void tegra_uart_handle_tx_pio(struct tegra_uart_port *tup)
{
	struct circ_buf *xmit = &tup->uport.state->xmit;

	tegra_uart_fill_tx_fifo(tup, tup->tx_bytes);
	tup->tx_in_progress = 0;
	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(&tup->uport);
	tegra_uart_start_next_tx(tup);
	return;
}

static void tegra_uart_handle_rx_pio(struct tegra_uart_port *tup,
		struct tty_port *tty)
{
	do {
		char flag = TTY_NORMAL;
		unsigned long lsr = 0;
		unsigned char ch;

		lsr = tegra_uart_read(tup, UART_LSR);
		if (!(lsr & UART_LSR_DR))
			break;

		flag = tegra_uart_decode_rx_error(tup, lsr);
		ch = (unsigned char) tegra_uart_read(tup, UART_RX);
		tup->uport.icount.rx++;

		if (!uart_handle_sysrq_char(&tup->uport, ch) && tty)
			tty_insert_flip_char(tty, ch, flag);
	} while (1);

	return;
}

static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
		struct tty_port *tty, int count)
{
	int copied;

	tup->uport.icount.rx += count;
	if (!tty) {
		dev_err(tup->uport.dev, "No tty port\n");
		return;
	}
	dma_sync_single_for_cpu(tup->uport.dev, tup->rx_dma_buf_phys,
				TEGRA_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
	copied = tty_insert_flip_string(tty,
			((unsigned char *)(tup->rx_dma_buf_virt)), count);
	if (copied != count) {
		WARN_ON(1);
		dev_err(tup->uport.dev, "RxData copy to tty layer failed\n");
	}
	dma_sync_single_for_device(tup->uport.dev, tup->rx_dma_buf_phys,
				TEGRA_UART_RX_DMA_BUFFER_SIZE, DMA_TO_DEVICE);
}

static void tegra_uart_rx_dma_complete(void *args)
{
	struct tegra_uart_port *tup = args;
	struct uart_port *u = &tup->uport;
	int count = tup->rx_bytes_requested;
	struct tty_struct *tty = tty_port_tty_get(&tup->uport.state->port);
	struct tty_port *port = &u->state->port;
	unsigned long flags;

	async_tx_ack(tup->rx_dma_desc);
	spin_lock_irqsave(&u->lock, flags);

	/* Deactivate flow control to stop sender */
	if (tup->rts_active)
		set_rts(tup, false);

	/* If we are here, DMA is stopped */
	if (count)
		tegra_uart_copy_rx_to_tty(tup, port, count);

	tegra_uart_handle_rx_pio(tup, port);
	if (tty) {
		spin_unlock_irqrestore(&u->lock, flags);
		tty_flip_buffer_push(port);
		spin_lock_irqsave(&u->lock, flags);
		tty_kref_put(tty);
	}
	tegra_uart_start_rx_dma(tup);

	/* Activate flow control to start transfer */
	if (tup->rts_active)
		set_rts(tup, true);

	spin_unlock_irqrestore(&u->lock, flags);
}

static void tegra_uart_handle_rx_dma(struct tegra_uart_port *tup,
		unsigned long *flags)
{
	struct dma_tx_state state;
	struct tty_struct *tty = tty_port_tty_get(&tup->uport.state->port);
	struct tty_port *port = &tup->uport.state->port;
	struct uart_port *u = &tup->uport;
	int count;

	/* Deactivate flow control to stop sender */
	if (tup->rts_active)
		set_rts(tup, false);

	dmaengine_terminate_all(tup->rx_dma_chan);
	dmaengine_tx_status(tup->rx_dma_chan,  tup->rx_cookie, &state);
	async_tx_ack(tup->rx_dma_desc);
	count = tup->rx_bytes_requested - state.residue;

	/* If we are here, DMA is stopped */
	if (count)
		tegra_uart_copy_rx_to_tty(tup, port, count);

	tegra_uart_handle_rx_pio(tup, port);
	if (tty) {
		spin_unlock_irqrestore(&u->lock, *flags);
		tty_flip_buffer_push(port);
		spin_lock_irqsave(&u->lock, *flags);
		tty_kref_put(tty);
	}
	tegra_uart_start_rx_dma(tup);

	if (tup->rts_active)
		set_rts(tup, true);
}

static int tegra_uart_start_rx_dma(struct tegra_uart_port *tup)
{
	unsigned int count = TEGRA_UART_RX_DMA_BUFFER_SIZE;

	tup->rx_dma_desc = dmaengine_prep_slave_single(tup->rx_dma_chan,
				tup->rx_dma_buf_phys, count, DMA_DEV_TO_MEM,
				DMA_PREP_INTERRUPT);
	if (!tup->rx_dma_desc) {
		dev_err(tup->uport.dev, "Not able to get desc for Rx\n");
		return -EIO;
	}

	tup->rx_dma_desc->callback = tegra_uart_rx_dma_complete;
	tup->rx_dma_desc->callback_param = tup;
	dma_sync_single_for_device(tup->uport.dev, tup->rx_dma_buf_phys,
				count, DMA_TO_DEVICE);
	tup->rx_bytes_requested = count;
	tup->rx_cookie = dmaengine_submit(tup->rx_dma_desc);
	dma_async_issue_pending(tup->rx_dma_chan);
	return 0;
}

static void tegra_uart_handle_modem_signal_change(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	unsigned long msr;

	msr = tegra_uart_read(tup, UART_MSR);
	if (!(msr & UART_MSR_ANY_DELTA))
		return;

	if (msr & UART_MSR_TERI)
		tup->uport.icount.rng++;
	if (msr & UART_MSR_DDSR)
		tup->uport.icount.dsr++;
	/* We may only get DDCD when HW init and reset */
	if (msr & UART_MSR_DDCD)
		uart_handle_dcd_change(&tup->uport, msr & UART_MSR_DCD);
	/* Will start/stop_tx accordingly */
	if (msr & UART_MSR_DCTS)
		uart_handle_cts_change(&tup->uport, msr & UART_MSR_CTS);
	return;
}

static irqreturn_t tegra_uart_isr(int irq, void *data)
{
	struct tegra_uart_port *tup = data;
	struct uart_port *u = &tup->uport;
	unsigned long iir;
	unsigned long ier;
	bool is_rx_int = false;
	unsigned long flags;

	spin_lock_irqsave(&u->lock, flags);
	while (1) {
		iir = tegra_uart_read(tup, UART_IIR);
		if (iir & UART_IIR_NO_INT) {
			if (is_rx_int) {
				tegra_uart_handle_rx_dma(tup, &flags);
				if (tup->rx_in_progress) {
					ier = tup->ier_shadow;
					ier |= (UART_IER_RLSI | UART_IER_RTOIE |
						TEGRA_UART_IER_EORD);
					tup->ier_shadow = ier;
					tegra_uart_write(tup, ier, UART_IER);
				}
			}
			spin_unlock_irqrestore(&u->lock, flags);
			return IRQ_HANDLED;
		}

		switch ((iir >> 1) & 0x7) {
		case 0: /* Modem signal change interrupt */
			tegra_uart_handle_modem_signal_change(u);
			break;

		case 1: /* Transmit interrupt only triggered when using PIO */
			tup->ier_shadow &= ~UART_IER_THRI;
			tegra_uart_write(tup, tup->ier_shadow, UART_IER);
			tegra_uart_handle_tx_pio(tup);
			break;

		case 4: /* End of data */
		case 6: /* Rx timeout */
		case 2: /* Receive */
			if (!is_rx_int) {
				is_rx_int = true;
				/* Disable Rx interrupts */
				ier = tup->ier_shadow;
				ier |= UART_IER_RDI;
				tegra_uart_write(tup, ier, UART_IER);
				ier &= ~(UART_IER_RDI | UART_IER_RLSI |
					UART_IER_RTOIE | TEGRA_UART_IER_EORD);
				tup->ier_shadow = ier;
				tegra_uart_write(tup, ier, UART_IER);
			}
			break;

		case 3: /* Receive error */
			tegra_uart_decode_rx_error(tup,
					tegra_uart_read(tup, UART_LSR));
			break;

		case 5: /* break nothing to handle */
		case 7: /* break nothing to handle */
			break;
		}
	}
}

static void tegra_uart_stop_rx(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	struct tty_struct *tty;
	struct tty_port *port = &u->state->port;
	struct dma_tx_state state;
	unsigned long ier;
	int count;

	if (tup->rts_active)
		set_rts(tup, false);

	if (!tup->rx_in_progress)
		return;

	tty = tty_port_tty_get(&tup->uport.state->port);

	tegra_uart_wait_sym_time(tup, 1); /* wait a character interval */

	ier = tup->ier_shadow;
	ier &= ~(UART_IER_RDI | UART_IER_RLSI | UART_IER_RTOIE |
					TEGRA_UART_IER_EORD);
	tup->ier_shadow = ier;
	tegra_uart_write(tup, ier, UART_IER);
	tup->rx_in_progress = 0;
	if (tup->rx_dma_chan) {
		dmaengine_terminate_all(tup->rx_dma_chan);
		dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
		async_tx_ack(tup->rx_dma_desc);
		count = tup->rx_bytes_requested - state.residue;
		tegra_uart_copy_rx_to_tty(tup, port, count);
		tegra_uart_handle_rx_pio(tup, port);
	} else {
		tegra_uart_handle_rx_pio(tup, port);
	}
	if (tty) {
		tty_flip_buffer_push(port);
		tty_kref_put(tty);
	}
	return;
}

static void tegra_uart_hw_deinit(struct tegra_uart_port *tup)
{
	unsigned long flags;
	unsigned long char_time = DIV_ROUND_UP(10000000, tup->current_baud);
	unsigned long fifo_empty_time = tup->uport.fifosize * char_time;
	unsigned long wait_time;
	unsigned long lsr;
	unsigned long msr;
	unsigned long mcr;

	/* Disable interrupts */
	tegra_uart_write(tup, 0, UART_IER);

	lsr = tegra_uart_read(tup, UART_LSR);
	if ((lsr & UART_LSR_TEMT) != UART_LSR_TEMT) {
		msr = tegra_uart_read(tup, UART_MSR);
		mcr = tegra_uart_read(tup, UART_MCR);
		if ((mcr & TEGRA_UART_MCR_CTS_EN) && (msr & UART_MSR_CTS))
			dev_err(tup->uport.dev,
				"Tx Fifo not empty, CTS disabled, waiting\n");

		/* Wait for Tx fifo to be empty */
		while ((lsr & UART_LSR_TEMT) != UART_LSR_TEMT) {
			wait_time = min(fifo_empty_time, 100lu);
			udelay(wait_time);
			fifo_empty_time -= wait_time;
			if (!fifo_empty_time) {
				msr = tegra_uart_read(tup, UART_MSR);
				mcr = tegra_uart_read(tup, UART_MCR);
				if ((mcr & TEGRA_UART_MCR_CTS_EN) &&
					(msr & UART_MSR_CTS))
					dev_err(tup->uport.dev,
						"Slave not ready\n");
				break;
			}
			lsr = tegra_uart_read(tup, UART_LSR);
		}
	}

	spin_lock_irqsave(&tup->uport.lock, flags);
	/* Reset the Rx and Tx FIFOs */
	tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR);
	tup->current_baud = 0;
	spin_unlock_irqrestore(&tup->uport.lock, flags);

	clk_disable_unprepare(tup->uart_clk);
}

static int tegra_uart_hw_init(struct tegra_uart_port *tup)
{
	int ret;

	tup->fcr_shadow = 0;
	tup->mcr_shadow = 0;
	tup->lcr_shadow = 0;
	tup->ier_shadow = 0;
	tup->current_baud = 0;

	clk_prepare_enable(tup->uart_clk);

	/* Reset the UART controller to clear all previous status.*/
	reset_control_assert(tup->rst);
	udelay(10);
	reset_control_deassert(tup->rst);

	tup->rx_in_progress = 0;
	tup->tx_in_progress = 0;

	/*
	 * Set the trigger level
	 *
	 * For PIO mode:
	 *
	 * For receive, this will interrupt the CPU after that many number of
	 * bytes are received, for the remaining bytes the receive timeout
	 * interrupt is received. Rx high watermark is set to 4.
	 *
	 * For transmit, if the trasnmit interrupt is enabled, this will
	 * interrupt the CPU when the number of entries in the FIFO reaches the
	 * low watermark. Tx low watermark is set to 16 bytes.
	 *
	 * For DMA mode:
	 *
	 * Set the Tx trigger to 16. This should match the DMA burst size that
	 * programmed in the DMA registers.
	 */
	tup->fcr_shadow = UART_FCR_ENABLE_FIFO;
	tup->fcr_shadow |= UART_FCR_R_TRIG_01;
	tup->fcr_shadow |= TEGRA_UART_TX_TRIG_16B;
	tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);

	/*
	 * Initialize the UART with default configuration
	 * (115200, N, 8, 1) so that the receive DMA buffer may be
	 * enqueued
	 */
	tup->lcr_shadow = TEGRA_UART_DEFAULT_LSR;
	tegra_set_baudrate(tup, TEGRA_UART_DEFAULT_BAUD);
	tup->fcr_shadow |= UART_FCR_DMA_SELECT;
	tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);

	ret = tegra_uart_start_rx_dma(tup);
	if (ret < 0) {
		dev_err(tup->uport.dev, "Not able to start Rx DMA\n");
		return ret;
	}
	tup->rx_in_progress = 1;

	/*
	 * Enable IE_RXS for the receive status interrupts like line errros.
	 * Enable IE_RX_TIMEOUT to get the bytes which cannot be DMA'd.
	 *
	 * If using DMA mode, enable EORD instead of receive interrupt which
	 * will interrupt after the UART is done with the receive instead of
	 * the interrupt when the FIFO "threshold" is reached.
	 *
	 * EORD is different interrupt than RX_TIMEOUT - RX_TIMEOUT occurs when
	 * the DATA is sitting in the FIFO and couldn't be transferred to the
	 * DMA as the DMA size alignment(4 bytes) is not met. EORD will be
	 * triggered when there is a pause of the incomming data stream for 4
	 * characters long.
	 *
	 * For pauses in the data which is not aligned to 4 bytes, we get
	 * both the EORD as well as RX_TIMEOUT - SW sees RX_TIMEOUT first
	 * then the EORD.
	 */
	tup->ier_shadow = UART_IER_RLSI | UART_IER_RTOIE | TEGRA_UART_IER_EORD;
	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
	return 0;
}

static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup,
			bool dma_to_memory)
{
	struct dma_chan *dma_chan;
	unsigned char *dma_buf;
	dma_addr_t dma_phys;
	int ret;
	struct dma_slave_config dma_sconfig;

	dma_chan = dma_request_slave_channel_reason(tup->uport.dev,
						dma_to_memory ? "rx" : "tx");
	if (IS_ERR(dma_chan)) {
		ret = PTR_ERR(dma_chan);
		dev_err(tup->uport.dev,
			"DMA channel alloc failed: %d\n", ret);
		return ret;
	}

	if (dma_to_memory) {
		dma_buf = dma_alloc_coherent(tup->uport.dev,
				TEGRA_UART_RX_DMA_BUFFER_SIZE,
				 &dma_phys, GFP_KERNEL);
		if (!dma_buf) {
			dev_err(tup->uport.dev,
				"Not able to allocate the dma buffer\n");
			dma_release_channel(dma_chan);
			return -ENOMEM;
		}
	} else {
		dma_phys = dma_map_single(tup->uport.dev,
			tup->uport.state->xmit.buf, UART_XMIT_SIZE,
			DMA_TO_DEVICE);
		dma_buf = tup->uport.state->xmit.buf;
	}

	if (dma_to_memory) {
		dma_sconfig.src_addr = tup->uport.mapbase;
		dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
		dma_sconfig.src_maxburst = 4;
	} else {
		dma_sconfig.dst_addr = tup->uport.mapbase;
		dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
		dma_sconfig.dst_maxburst = 16;
	}

	ret = dmaengine_slave_config(dma_chan, &dma_sconfig);
	if (ret < 0) {
		dev_err(tup->uport.dev,
			"Dma slave config failed, err = %d\n", ret);
		goto scrub;
	}

	if (dma_to_memory) {
		tup->rx_dma_chan = dma_chan;
		tup->rx_dma_buf_virt = dma_buf;
		tup->rx_dma_buf_phys = dma_phys;
	} else {
		tup->tx_dma_chan = dma_chan;
		tup->tx_dma_buf_virt = dma_buf;
		tup->tx_dma_buf_phys = dma_phys;
	}
	return 0;

scrub:
	dma_release_channel(dma_chan);
	return ret;
}

static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,
		bool dma_to_memory)
{
	struct dma_chan *dma_chan;

	if (dma_to_memory) {
		dma_free_coherent(tup->uport.dev, TEGRA_UART_RX_DMA_BUFFER_SIZE,
				tup->rx_dma_buf_virt, tup->rx_dma_buf_phys);
		dma_chan = tup->rx_dma_chan;
		tup->rx_dma_chan = NULL;
		tup->rx_dma_buf_phys = 0;
		tup->rx_dma_buf_virt = NULL;
	} else {
		dma_unmap_single(tup->uport.dev, tup->tx_dma_buf_phys,
			UART_XMIT_SIZE, DMA_TO_DEVICE);
		dma_chan = tup->tx_dma_chan;
		tup->tx_dma_chan = NULL;
		tup->tx_dma_buf_phys = 0;
		tup->tx_dma_buf_virt = NULL;
	}
	dma_release_channel(dma_chan);
}

static int tegra_uart_startup(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	int ret;

	ret = tegra_uart_dma_channel_allocate(tup, false);
	if (ret < 0) {
		dev_err(u->dev, "Tx Dma allocation failed, err = %d\n", ret);
		return ret;
	}

	ret = tegra_uart_dma_channel_allocate(tup, true);
	if (ret < 0) {
		dev_err(u->dev, "Rx Dma allocation failed, err = %d\n", ret);
		goto fail_rx_dma;
	}

	ret = tegra_uart_hw_init(tup);
	if (ret < 0) {
		dev_err(u->dev, "Uart HW init failed, err = %d\n", ret);
		goto fail_hw_init;
	}

	ret = request_irq(u->irq, tegra_uart_isr, 0,
				dev_name(u->dev), tup);
	if (ret < 0) {
		dev_err(u->dev, "Failed to register ISR for IRQ %d\n", u->irq);
		goto fail_hw_init;
	}
	return 0;

fail_hw_init:
	tegra_uart_dma_channel_free(tup, true);
fail_rx_dma:
	tegra_uart_dma_channel_free(tup, false);
	return ret;
}

/*
 * Flush any TX data submitted for DMA and PIO. Called when the
 * TX circular buffer is reset.
 */
static void tegra_uart_flush_buffer(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);

	tup->tx_bytes = 0;
	if (tup->tx_dma_chan)
		dmaengine_terminate_all(tup->tx_dma_chan);
	return;
}

static void tegra_uart_shutdown(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);

	tegra_uart_hw_deinit(tup);

	tup->rx_in_progress = 0;
	tup->tx_in_progress = 0;

	tegra_uart_dma_channel_free(tup, true);
	tegra_uart_dma_channel_free(tup, false);
	free_irq(u->irq, tup);

	tegra_uart_flush_buffer(u);
}

static void tegra_uart_enable_ms(struct uart_port *u)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);

	if (tup->enable_modem_interrupt) {
		tup->ier_shadow |= UART_IER_MSI;
		tegra_uart_write(tup, tup->ier_shadow, UART_IER);
	}
}

static void tegra_uart_set_termios(struct uart_port *u,
		struct ktermios *termios, struct ktermios *oldtermios)
{
	struct tegra_uart_port *tup = to_tegra_uport(u);
	unsigned int baud;
	unsigned long flags;
	unsigned int lcr;
	int symb_bit = 1;
	struct clk *parent_clk = clk_get_parent(tup->uart_clk);
	unsigned long parent_clk_rate = clk_get_rate(parent_clk);
	int max_divider = (tup->cdata->support_clk_src_div) ? 0x7FFF : 0xFFFF;

	max_divider *= 16;
	spin_lock_irqsave(&u->lock, flags);

	/* Changing configuration, it is safe to stop any rx now */
	if (tup->rts_active)
		set_rts(tup, false);

	/* Clear all interrupts as configuration is going to be change */
	tegra_uart_write(tup, tup->ier_shadow | UART_IER_RDI, UART_IER);
	tegra_uart_read(tup, UART_IER);
	tegra_uart_write(tup, 0, UART_IER);
	tegra_uart_read(tup, UART_IER);

	/* Parity */
	lcr = tup->lcr_shadow;
	lcr &= ~UART_LCR_PARITY;

	/* CMSPAR isn't supported by this driver */
	termios->c_cflag &= ~CMSPAR;

	if ((termios->c_cflag & PARENB) == PARENB) {
		symb_bit++;
		if (termios->c_cflag & PARODD) {
			lcr |= UART_LCR_PARITY;
			lcr &= ~UART_LCR_EPAR;
			lcr &= ~UART_LCR_SPAR;
		} else {
			lcr |= UART_LCR_PARITY;
			lcr |= UART_LCR_EPAR;
			lcr &= ~UART_LCR_SPAR;
		}
	}

	lcr &= ~UART_LCR_WLEN8;
	switch (termios->c_cflag & CSIZE) {
	case CS5:
		lcr |= UART_LCR_WLEN5;
		symb_bit += 5;
		break;
	case CS6:
		lcr |= UART_LCR_WLEN6;
		symb_bit += 6;
		break;
	case CS7:
		lcr |= UART_LCR_WLEN7;
		symb_bit += 7;
		break;
	default:
		lcr |= UART_LCR_WLEN8;
		symb_bit += 8;
		break;
	}

	/* Stop bits */
	if (termios->c_cflag & CSTOPB) {
		lcr |= UART_LCR_STOP;
		symb_bit += 2;
	} else {
		lcr &= ~UART_LCR_STOP;
		symb_bit++;
	}

	tegra_uart_write(tup, lcr, UART_LCR);
	tup->lcr_shadow = lcr;
	tup->symb_bit = symb_bit;

	/* Baud rate. */
	baud = uart_get_baud_rate(u, termios, oldtermios,
			parent_clk_rate/max_divider,
			parent_clk_rate/16);
	spin_unlock_irqrestore(&u->lock, flags);
	tegra_set_baudrate(tup, baud);
	if (tty_termios_baud_rate(termios))
		tty_termios_encode_baud_rate(termios, baud, baud);
	spin_lock_irqsave(&u->lock, flags);

	/* Flow control */
	if (termios->c_cflag & CRTSCTS)	{
		tup->mcr_shadow |= TEGRA_UART_MCR_CTS_EN;
		tup->mcr_shadow &= ~TEGRA_UART_MCR_RTS_EN;
		tegra_uart_write(tup, tup->mcr_shadow, UART_MCR);
		/* if top layer has asked to set rts active then do so here */
		if (tup->rts_active)
			set_rts(tup, true);
	} else {
		tup->mcr_shadow &= ~TEGRA_UART_MCR_CTS_EN;
		tup->mcr_shadow &= ~TEGRA_UART_MCR_RTS_EN;
		tegra_uart_write(tup, tup->mcr_shadow, UART_MCR);
	}

	/* update the port timeout based on new settings */
	uart_update_timeout(u, termios->c_cflag, baud);

	/* Make sure all write has completed */
	tegra_uart_read(tup, UART_IER);

	/* Reenable interrupt */
	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
	tegra_uart_read(tup, UART_IER);

	spin_unlock_irqrestore(&u->lock, flags);
	return;
}

static const char *tegra_uart_type(struct uart_port *u)
{
	return TEGRA_UART_TYPE;
}

static struct uart_ops tegra_uart_ops = {
	.tx_empty	= tegra_uart_tx_empty,
	.set_mctrl	= tegra_uart_set_mctrl,
	.get_mctrl	= tegra_uart_get_mctrl,
	.stop_tx	= tegra_uart_stop_tx,
	.start_tx	= tegra_uart_start_tx,
	.stop_rx	= tegra_uart_stop_rx,
	.flush_buffer	= tegra_uart_flush_buffer,
	.enable_ms	= tegra_uart_enable_ms,
	.break_ctl	= tegra_uart_break_ctl,
	.startup	= tegra_uart_startup,
	.shutdown	= tegra_uart_shutdown,
	.set_termios	= tegra_uart_set_termios,
	.type		= tegra_uart_type,
	.request_port	= tegra_uart_request_port,
	.release_port	= tegra_uart_release_port,
};

static struct uart_driver tegra_uart_driver = {
	.owner		= THIS_MODULE,
	.driver_name	= "tegra_hsuart",
	.dev_name	= "ttyTHS",
	.cons		= NULL,
	.nr		= TEGRA_UART_MAXIMUM,
};

static int tegra_uart_parse_dt(struct platform_device *pdev,
	struct tegra_uart_port *tup)
{
	struct device_node *np = pdev->dev.of_node;
	int port;

	port = of_alias_get_id(np, "serial");
	if (port < 0) {
		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", port);
		return port;
	}
	tup->uport.line = port;

	tup->enable_modem_interrupt = of_property_read_bool(np,
					"nvidia,enable-modem-interrupt");
	return 0;
}

static struct tegra_uart_chip_data tegra20_uart_chip_data = {
	.tx_fifo_full_status		= false,
	.allow_txfifo_reset_fifo_mode	= true,
	.support_clk_src_div		= false,
};

static struct tegra_uart_chip_data tegra30_uart_chip_data = {
	.tx_fifo_full_status		= true,
	.allow_txfifo_reset_fifo_mode	= false,
	.support_clk_src_div		= true,
};

static const struct of_device_id tegra_uart_of_match[] = {
	{
		.compatible	= "nvidia,tegra30-hsuart",
		.data		= &tegra30_uart_chip_data,
	}, {
		.compatible	= "nvidia,tegra20-hsuart",
		.data		= &tegra20_uart_chip_data,
	}, {
	},
};
MODULE_DEVICE_TABLE(of, tegra_uart_of_match);

static int tegra_uart_probe(struct platform_device *pdev)
{
	struct tegra_uart_port *tup;
	struct uart_port *u;
	struct resource *resource;
	int ret;
	const struct tegra_uart_chip_data *cdata;
	const struct of_device_id *match;

	match = of_match_device(tegra_uart_of_match, &pdev->dev);
	if (!match) {
		dev_err(&pdev->dev, "Error: No device match found\n");
		return -ENODEV;
	}
	cdata = match->data;

	tup = devm_kzalloc(&pdev->dev, sizeof(*tup), GFP_KERNEL);
	if (!tup) {
		dev_err(&pdev->dev, "Failed to allocate memory for tup\n");
		return -ENOMEM;
	}

	ret = tegra_uart_parse_dt(pdev, tup);
	if (ret < 0)
		return ret;

	u = &tup->uport;
	u->dev = &pdev->dev;
	u->ops = &tegra_uart_ops;
	u->type = PORT_TEGRA;
	u->fifosize = 32;
	tup->cdata = cdata;

	platform_set_drvdata(pdev, tup);
	resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!resource) {
		dev_err(&pdev->dev, "No IO memory resource\n");
		return -ENODEV;
	}

	u->mapbase = resource->start;
	u->membase = devm_ioremap_resource(&pdev->dev, resource);
	if (IS_ERR(u->membase))
		return PTR_ERR(u->membase);

	tup->uart_clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(tup->uart_clk)) {
		dev_err(&pdev->dev, "Couldn't get the clock\n");
		return PTR_ERR(tup->uart_clk);
	}

	tup->rst = devm_reset_control_get(&pdev->dev, "serial");
	if (IS_ERR(tup->rst)) {
		dev_err(&pdev->dev, "Couldn't get the reset\n");
		return PTR_ERR(tup->rst);
	}

	u->iotype = UPIO_MEM32;
	u->irq = platform_get_irq(pdev, 0);
	u->regshift = 2;
	ret = uart_add_one_port(&tegra_uart_driver, u);
	if (ret < 0) {
		dev_err(&pdev->dev, "Failed to add uart port, err %d\n", ret);
		return ret;
	}
	return ret;
}

static int tegra_uart_remove(struct platform_device *pdev)
{
	struct tegra_uart_port *tup = platform_get_drvdata(pdev);
	struct uart_port *u = &tup->uport;

	uart_remove_one_port(&tegra_uart_driver, u);
	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int tegra_uart_suspend(struct device *dev)
{
	struct tegra_uart_port *tup = dev_get_drvdata(dev);
	struct uart_port *u = &tup->uport;

	return uart_suspend_port(&tegra_uart_driver, u);
}

static int tegra_uart_resume(struct device *dev)
{
	struct tegra_uart_port *tup = dev_get_drvdata(dev);
	struct uart_port *u = &tup->uport;

	return uart_resume_port(&tegra_uart_driver, u);
}
#endif

static const struct dev_pm_ops tegra_uart_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(tegra_uart_suspend, tegra_uart_resume)
};

static struct platform_driver tegra_uart_platform_driver = {
	.probe		= tegra_uart_probe,
	.remove		= tegra_uart_remove,
	.driver		= {
		.name	= "serial-tegra",
		.of_match_table = tegra_uart_of_match,
		.pm	= &tegra_uart_pm_ops,
	},
};

static int __init tegra_uart_init(void)
{
	int ret;

	ret = uart_register_driver(&tegra_uart_driver);
	if (ret < 0) {
		pr_err("Could not register %s driver\n",
			tegra_uart_driver.driver_name);
		return ret;
	}

	ret = platform_driver_register(&tegra_uart_platform_driver);
	if (ret < 0) {
		pr_err("Uart platform driver register failed, e = %d\n", ret);
		uart_unregister_driver(&tegra_uart_driver);
		return ret;
	}
	return 0;
}

static void __exit tegra_uart_exit(void)
{
	pr_info("Unloading tegra uart driver\n");
	platform_driver_unregister(&tegra_uart_platform_driver);
	uart_unregister_driver(&tegra_uart_driver);
}

module_init(tegra_uart_init);
module_exit(tegra_uart_exit);

MODULE_ALIAS("platform:serial-tegra");
MODULE_DESCRIPTION("High speed UART driver for tegra chipset");
MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_LICENSE("GPL v2");