summaryrefslogtreecommitdiffstats
path: root/drivers/tty/serial/mxs-auart.c
blob: d549fe1fa42abdce8611645d1038dfb11b5e0654 (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
/*
 * Freescale STMP37XX/STMP378X Application UART driver
 *
 * Author: dmitry pervushin <dimka@embeddedalley.com>
 *
 * Copyright 2008-2010 Freescale Semiconductor, Inc.
 * Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.
 *
 * The code contained herein is licensed under the GNU General Public
 * License. You may obtain a copy of the GNU General Public License
 * Version 2 or later at the following locations:
 *
 * http://www.opensource.org/licenses/gpl-license.html
 * http://www.gnu.org/copyleft/gpl.html
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/pinctrl/consumer.h>
#include <linux/of_device.h>
#include <linux/dma-mapping.h>
#include <linux/fsl/mxs-dma.h>

#include <asm/cacheflush.h>

#define MXS_AUART_PORTS 5

#define AUART_CTRL0			0x00000000
#define AUART_CTRL0_SET			0x00000004
#define AUART_CTRL0_CLR			0x00000008
#define AUART_CTRL0_TOG			0x0000000c
#define AUART_CTRL1			0x00000010
#define AUART_CTRL1_SET			0x00000014
#define AUART_CTRL1_CLR			0x00000018
#define AUART_CTRL1_TOG			0x0000001c
#define AUART_CTRL2			0x00000020
#define AUART_CTRL2_SET			0x00000024
#define AUART_CTRL2_CLR			0x00000028
#define AUART_CTRL2_TOG			0x0000002c
#define AUART_LINECTRL			0x00000030
#define AUART_LINECTRL_SET		0x00000034
#define AUART_LINECTRL_CLR		0x00000038
#define AUART_LINECTRL_TOG		0x0000003c
#define AUART_LINECTRL2			0x00000040
#define AUART_LINECTRL2_SET		0x00000044
#define AUART_LINECTRL2_CLR		0x00000048
#define AUART_LINECTRL2_TOG		0x0000004c
#define AUART_INTR			0x00000050
#define AUART_INTR_SET			0x00000054
#define AUART_INTR_CLR			0x00000058
#define AUART_INTR_TOG			0x0000005c
#define AUART_DATA			0x00000060
#define AUART_STAT			0x00000070
#define AUART_DEBUG			0x00000080
#define AUART_VERSION			0x00000090
#define AUART_AUTOBAUD			0x000000a0

#define AUART_CTRL0_SFTRST			(1 << 31)
#define AUART_CTRL0_CLKGATE			(1 << 30)
#define AUART_CTRL0_RXTO_ENABLE			(1 << 27)
#define AUART_CTRL0_RXTIMEOUT(v)		(((v) & 0x7ff) << 16)
#define AUART_CTRL0_XFER_COUNT(v)		((v) & 0xffff)

#define AUART_CTRL1_XFER_COUNT(v)		((v) & 0xffff)

#define AUART_CTRL2_DMAONERR			(1 << 26)
#define AUART_CTRL2_TXDMAE			(1 << 25)
#define AUART_CTRL2_RXDMAE			(1 << 24)

#define AUART_CTRL2_CTSEN			(1 << 15)
#define AUART_CTRL2_RTSEN			(1 << 14)
#define AUART_CTRL2_RTS				(1 << 11)
#define AUART_CTRL2_RXE				(1 << 9)
#define AUART_CTRL2_TXE				(1 << 8)
#define AUART_CTRL2_UARTEN			(1 << 0)

#define AUART_LINECTRL_BAUD_DIVINT_SHIFT	16
#define AUART_LINECTRL_BAUD_DIVINT_MASK		0xffff0000
#define AUART_LINECTRL_BAUD_DIVINT(v)		(((v) & 0xffff) << 16)
#define AUART_LINECTRL_BAUD_DIVFRAC_SHIFT	8
#define AUART_LINECTRL_BAUD_DIVFRAC_MASK	0x00003f00
#define AUART_LINECTRL_BAUD_DIVFRAC(v)		(((v) & 0x3f) << 8)
#define AUART_LINECTRL_WLEN_MASK		0x00000060
#define AUART_LINECTRL_WLEN(v)			(((v) & 0x3) << 5)
#define AUART_LINECTRL_FEN			(1 << 4)
#define AUART_LINECTRL_STP2			(1 << 3)
#define AUART_LINECTRL_EPS			(1 << 2)
#define AUART_LINECTRL_PEN			(1 << 1)
#define AUART_LINECTRL_BRK			(1 << 0)

#define AUART_INTR_RTIEN			(1 << 22)
#define AUART_INTR_TXIEN			(1 << 21)
#define AUART_INTR_RXIEN			(1 << 20)
#define AUART_INTR_CTSMIEN			(1 << 17)
#define AUART_INTR_RTIS				(1 << 6)
#define AUART_INTR_TXIS				(1 << 5)
#define AUART_INTR_RXIS				(1 << 4)
#define AUART_INTR_CTSMIS			(1 << 1)

#define AUART_STAT_BUSY				(1 << 29)
#define AUART_STAT_CTS				(1 << 28)
#define AUART_STAT_TXFE				(1 << 27)
#define AUART_STAT_TXFF				(1 << 25)
#define AUART_STAT_RXFE				(1 << 24)
#define AUART_STAT_OERR				(1 << 19)
#define AUART_STAT_BERR				(1 << 18)
#define AUART_STAT_PERR				(1 << 17)
#define AUART_STAT_FERR				(1 << 16)
#define AUART_STAT_RXCOUNT_MASK			0xffff

static struct uart_driver auart_driver;

enum mxs_auart_type {
	IMX23_AUART,
	IMX28_AUART,
};

struct mxs_auart_port {
	struct uart_port port;

#define MXS_AUART_DMA_CONFIG	0x1
#define MXS_AUART_DMA_ENABLED	0x2
#define MXS_AUART_DMA_TX_SYNC	2  /* bit 2 */
#define MXS_AUART_DMA_RX_READY	3  /* bit 3 */
	unsigned long flags;
	unsigned int ctrl;
	enum mxs_auart_type devtype;

	unsigned int irq;

	struct clk *clk;
	struct device *dev;

	/* for DMA */
	struct mxs_dma_data dma_data;
	int dma_channel_rx, dma_channel_tx;
	int dma_irq_rx, dma_irq_tx;
	int dma_channel;

	struct scatterlist tx_sgl;
	struct dma_chan	*tx_dma_chan;
	void *tx_dma_buf;

	struct scatterlist rx_sgl;
	struct dma_chan	*rx_dma_chan;
	void *rx_dma_buf;
};

static struct platform_device_id mxs_auart_devtype[] = {
	{ .name = "mxs-auart-imx23", .driver_data = IMX23_AUART },
	{ .name = "mxs-auart-imx28", .driver_data = IMX28_AUART },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(platform, mxs_auart_devtype);

static struct of_device_id mxs_auart_dt_ids[] = {
	{
		.compatible = "fsl,imx28-auart",
		.data = &mxs_auart_devtype[IMX28_AUART]
	}, {
		.compatible = "fsl,imx23-auart",
		.data = &mxs_auart_devtype[IMX23_AUART]
	}, { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mxs_auart_dt_ids);

static inline int is_imx28_auart(struct mxs_auart_port *s)
{
	return s->devtype == IMX28_AUART;
}

static inline bool auart_dma_enabled(struct mxs_auart_port *s)
{
	return s->flags & MXS_AUART_DMA_ENABLED;
}

static void mxs_auart_stop_tx(struct uart_port *u);

#define to_auart_port(u) container_of(u, struct mxs_auart_port, port)

static void mxs_auart_tx_chars(struct mxs_auart_port *s);

static void dma_tx_callback(void *param)
{
	struct mxs_auart_port *s = param;
	struct circ_buf *xmit = &s->port.state->xmit;

	dma_unmap_sg(s->dev, &s->tx_sgl, 1, DMA_TO_DEVICE);

	/* clear the bit used to serialize the DMA tx. */
	clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);
	smp_mb__after_clear_bit();

	/* wake up the possible processes. */
	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(&s->port);

	mxs_auart_tx_chars(s);
}

static int mxs_auart_dma_tx(struct mxs_auart_port *s, int size)
{
	struct dma_async_tx_descriptor *desc;
	struct scatterlist *sgl = &s->tx_sgl;
	struct dma_chan *channel = s->tx_dma_chan;
	u32 pio;

	/* [1] : send PIO. Note, the first pio word is CTRL1. */
	pio = AUART_CTRL1_XFER_COUNT(size);
	desc = dmaengine_prep_slave_sg(channel, (struct scatterlist *)&pio,
					1, DMA_TRANS_NONE, 0);
	if (!desc) {
		dev_err(s->dev, "step 1 error\n");
		return -EINVAL;
	}

	/* [2] : set DMA buffer. */
	sg_init_one(sgl, s->tx_dma_buf, size);
	dma_map_sg(s->dev, sgl, 1, DMA_TO_DEVICE);
	desc = dmaengine_prep_slave_sg(channel, sgl,
			1, DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
	if (!desc) {
		dev_err(s->dev, "step 2 error\n");
		return -EINVAL;
	}

	/* [3] : submit the DMA */
	desc->callback = dma_tx_callback;
	desc->callback_param = s;
	dmaengine_submit(desc);
	dma_async_issue_pending(channel);
	return 0;
}

static void mxs_auart_tx_chars(struct mxs_auart_port *s)
{
	struct circ_buf *xmit = &s->port.state->xmit;

	if (auart_dma_enabled(s)) {
		u32 i = 0;
		int size;
		void *buffer = s->tx_dma_buf;

		if (test_and_set_bit(MXS_AUART_DMA_TX_SYNC, &s->flags))
			return;

		while (!uart_circ_empty(xmit) && !uart_tx_stopped(&s->port)) {
			size = min_t(u32, UART_XMIT_SIZE - i,
				     CIRC_CNT_TO_END(xmit->head,
						     xmit->tail,
						     UART_XMIT_SIZE));
			memcpy(buffer + i, xmit->buf + xmit->tail, size);
			xmit->tail = (xmit->tail + size) & (UART_XMIT_SIZE - 1);

			i += size;
			if (i >= UART_XMIT_SIZE)
				break;
		}

		if (uart_tx_stopped(&s->port))
			mxs_auart_stop_tx(&s->port);

		if (i) {
			mxs_auart_dma_tx(s, i);
		} else {
			clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);
			smp_mb__after_clear_bit();
		}
		return;
	}


	while (!(readl(s->port.membase + AUART_STAT) &
		 AUART_STAT_TXFF)) {
		if (s->port.x_char) {
			s->port.icount.tx++;
			writel(s->port.x_char,
				     s->port.membase + AUART_DATA);
			s->port.x_char = 0;
			continue;
		}
		if (!uart_circ_empty(xmit) && !uart_tx_stopped(&s->port)) {
			s->port.icount.tx++;
			writel(xmit->buf[xmit->tail],
				     s->port.membase + AUART_DATA);
			xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		} else
			break;
	}
	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(&s->port);

	if (uart_circ_empty(&(s->port.state->xmit)))
		writel(AUART_INTR_TXIEN,
			     s->port.membase + AUART_INTR_CLR);
	else
		writel(AUART_INTR_TXIEN,
			     s->port.membase + AUART_INTR_SET);

	if (uart_tx_stopped(&s->port))
		mxs_auart_stop_tx(&s->port);
}

static void mxs_auart_rx_char(struct mxs_auart_port *s)
{
	int flag;
	u32 stat;
	u8 c;

	c = readl(s->port.membase + AUART_DATA);
	stat = readl(s->port.membase + AUART_STAT);

	flag = TTY_NORMAL;
	s->port.icount.rx++;

	if (stat & AUART_STAT_BERR) {
		s->port.icount.brk++;
		if (uart_handle_break(&s->port))
			goto out;
	} else if (stat & AUART_STAT_PERR) {
		s->port.icount.parity++;
	} else if (stat & AUART_STAT_FERR) {
		s->port.icount.frame++;
	}

	/*
	 * Mask off conditions which should be ingored.
	 */
	stat &= s->port.read_status_mask;

	if (stat & AUART_STAT_BERR) {
		flag = TTY_BREAK;
	} else if (stat & AUART_STAT_PERR)
		flag = TTY_PARITY;
	else if (stat & AUART_STAT_FERR)
		flag = TTY_FRAME;

	if (stat & AUART_STAT_OERR)
		s->port.icount.overrun++;

	if (uart_handle_sysrq_char(&s->port, c))
		goto out;

	uart_insert_char(&s->port, stat, AUART_STAT_OERR, c, flag);
out:
	writel(stat, s->port.membase + AUART_STAT);
}

static void mxs_auart_rx_chars(struct mxs_auart_port *s)
{
	u32 stat = 0;

	for (;;) {
		stat = readl(s->port.membase + AUART_STAT);
		if (stat & AUART_STAT_RXFE)
			break;
		mxs_auart_rx_char(s);
	}

	writel(stat, s->port.membase + AUART_STAT);
	tty_flip_buffer_push(&s->port.state->port);
}

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

static int mxs_auart_verify_port(struct uart_port *u,
				    struct serial_struct *ser)
{
	if (u->type != PORT_UNKNOWN && u->type != PORT_IMX)
		return -EINVAL;
	return 0;
}

static void mxs_auart_config_port(struct uart_port *u, int flags)
{
}

static const char *mxs_auart_type(struct uart_port *u)
{
	struct mxs_auart_port *s = to_auart_port(u);

	return dev_name(s->dev);
}

static void mxs_auart_release_port(struct uart_port *u)
{
}

static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl)
{
	struct mxs_auart_port *s = to_auart_port(u);

	u32 ctrl = readl(u->membase + AUART_CTRL2);

	ctrl &= ~(AUART_CTRL2_RTSEN | AUART_CTRL2_RTS);
	if (mctrl & TIOCM_RTS) {
		if (tty_port_cts_enabled(&u->state->port))
			ctrl |= AUART_CTRL2_RTSEN;
		else
			ctrl |= AUART_CTRL2_RTS;
	}

	s->ctrl = mctrl;
	writel(ctrl, u->membase + AUART_CTRL2);
}

static u32 mxs_auart_get_mctrl(struct uart_port *u)
{
	struct mxs_auart_port *s = to_auart_port(u);
	u32 stat = readl(u->membase + AUART_STAT);
	int ctrl2 = readl(u->membase + AUART_CTRL2);
	u32 mctrl = s->ctrl;

	mctrl &= ~TIOCM_CTS;
	if (stat & AUART_STAT_CTS)
		mctrl |= TIOCM_CTS;

	if (ctrl2 & AUART_CTRL2_RTS)
		mctrl |= TIOCM_RTS;

	return mctrl;
}

static bool mxs_auart_dma_filter(struct dma_chan *chan, void *param)
{
	struct mxs_auart_port *s = param;

	if (!mxs_dma_is_apbx(chan))
		return false;

	if (s->dma_channel == chan->chan_id) {
		chan->private = &s->dma_data;
		return true;
	}
	return false;
}

static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s);
static void dma_rx_callback(void *arg)
{
	struct mxs_auart_port *s = (struct mxs_auart_port *) arg;
	struct tty_port *port = &s->port.state->port;
	int count;
	u32 stat;

	dma_unmap_sg(s->dev, &s->rx_sgl, 1, DMA_FROM_DEVICE);

	stat = readl(s->port.membase + AUART_STAT);
	stat &= ~(AUART_STAT_OERR | AUART_STAT_BERR |
			AUART_STAT_PERR | AUART_STAT_FERR);

	count = stat & AUART_STAT_RXCOUNT_MASK;
	tty_insert_flip_string(port, s->rx_dma_buf, count);

	writel(stat, s->port.membase + AUART_STAT);
	tty_flip_buffer_push(port);

	/* start the next DMA for RX. */
	mxs_auart_dma_prep_rx(s);
}

static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s)
{
	struct dma_async_tx_descriptor *desc;
	struct scatterlist *sgl = &s->rx_sgl;
	struct dma_chan *channel = s->rx_dma_chan;
	u32 pio[1];

	/* [1] : send PIO */
	pio[0] = AUART_CTRL0_RXTO_ENABLE
		| AUART_CTRL0_RXTIMEOUT(0x80)
		| AUART_CTRL0_XFER_COUNT(UART_XMIT_SIZE);
	desc = dmaengine_prep_slave_sg(channel, (struct scatterlist *)pio,
					1, DMA_TRANS_NONE, 0);
	if (!desc) {
		dev_err(s->dev, "step 1 error\n");
		return -EINVAL;
	}

	/* [2] : send DMA request */
	sg_init_one(sgl, s->rx_dma_buf, UART_XMIT_SIZE);
	dma_map_sg(s->dev, sgl, 1, DMA_FROM_DEVICE);
	desc = dmaengine_prep_slave_sg(channel, sgl, 1, DMA_DEV_TO_MEM,
					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
	if (!desc) {
		dev_err(s->dev, "step 2 error\n");
		return -1;
	}

	/* [3] : submit the DMA, but do not issue it. */
	desc->callback = dma_rx_callback;
	desc->callback_param = s;
	dmaengine_submit(desc);
	dma_async_issue_pending(channel);
	return 0;
}

static void mxs_auart_dma_exit_channel(struct mxs_auart_port *s)
{
	if (s->tx_dma_chan) {
		dma_release_channel(s->tx_dma_chan);
		s->tx_dma_chan = NULL;
	}
	if (s->rx_dma_chan) {
		dma_release_channel(s->rx_dma_chan);
		s->rx_dma_chan = NULL;
	}

	kfree(s->tx_dma_buf);
	kfree(s->rx_dma_buf);
	s->tx_dma_buf = NULL;
	s->rx_dma_buf = NULL;
}

static void mxs_auart_dma_exit(struct mxs_auart_port *s)
{

	writel(AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE | AUART_CTRL2_DMAONERR,
		s->port.membase + AUART_CTRL2_CLR);

	mxs_auart_dma_exit_channel(s);
	s->flags &= ~MXS_AUART_DMA_ENABLED;
	clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);
	clear_bit(MXS_AUART_DMA_RX_READY, &s->flags);
}

static int mxs_auart_dma_init(struct mxs_auart_port *s)
{
	dma_cap_mask_t mask;

	if (auart_dma_enabled(s))
		return 0;

	/* We do not get the right DMA channels. */
	if (s->dma_channel_rx == -1 || s->dma_channel_tx == -1)
		return -EINVAL;

	/* init for RX */
	dma_cap_zero(mask);
	dma_cap_set(DMA_SLAVE, mask);
	s->dma_channel = s->dma_channel_rx;
	s->dma_data.chan_irq = s->dma_irq_rx;
	s->rx_dma_chan = dma_request_channel(mask, mxs_auart_dma_filter, s);
	if (!s->rx_dma_chan)
		goto err_out;
	s->rx_dma_buf = kzalloc(UART_XMIT_SIZE, GFP_KERNEL | GFP_DMA);
	if (!s->rx_dma_buf)
		goto err_out;

	/* init for TX */
	s->dma_channel = s->dma_channel_tx;
	s->dma_data.chan_irq = s->dma_irq_tx;
	s->tx_dma_chan = dma_request_channel(mask, mxs_auart_dma_filter, s);
	if (!s->tx_dma_chan)
		goto err_out;
	s->tx_dma_buf = kzalloc(UART_XMIT_SIZE, GFP_KERNEL | GFP_DMA);
	if (!s->tx_dma_buf)
		goto err_out;

	/* set the flags */
	s->flags |= MXS_AUART_DMA_ENABLED;
	dev_dbg(s->dev, "enabled the DMA support.");

	return 0;

err_out:
	mxs_auart_dma_exit_channel(s);
	return -EINVAL;

}

static void mxs_auart_settermios(struct uart_port *u,
				 struct ktermios *termios,
				 struct ktermios *old)
{
	struct mxs_auart_port *s = to_auart_port(u);
	u32 bm, ctrl, ctrl2, div;
	unsigned int cflag, baud;

	cflag = termios->c_cflag;

	ctrl = AUART_LINECTRL_FEN;
	ctrl2 = readl(u->membase + AUART_CTRL2);

	/* byte size */
	switch (cflag & CSIZE) {
	case CS5:
		bm = 0;
		break;
	case CS6:
		bm = 1;
		break;
	case CS7:
		bm = 2;
		break;
	case CS8:
		bm = 3;
		break;
	default:
		return;
	}

	ctrl |= AUART_LINECTRL_WLEN(bm);

	/* parity */
	if (cflag & PARENB) {
		ctrl |= AUART_LINECTRL_PEN;
		if ((cflag & PARODD) == 0)
			ctrl |= AUART_LINECTRL_EPS;
	}

	u->read_status_mask = 0;

	if (termios->c_iflag & INPCK)
		u->read_status_mask |= AUART_STAT_PERR;
	if (termios->c_iflag & (BRKINT | PARMRK))
		u->read_status_mask |= AUART_STAT_BERR;

	/*
	 * Characters to ignore
	 */
	u->ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
		u->ignore_status_mask |= AUART_STAT_PERR;
	if (termios->c_iflag & IGNBRK) {
		u->ignore_status_mask |= AUART_STAT_BERR;
		/*
		 * If we're ignoring parity and break indicators,
		 * ignore overruns too (for real raw support).
		 */
		if (termios->c_iflag & IGNPAR)
			u->ignore_status_mask |= AUART_STAT_OERR;
	}

	/*
	 * ignore all characters if CREAD is not set
	 */
	if (cflag & CREAD)
		ctrl2 |= AUART_CTRL2_RXE;
	else
		ctrl2 &= ~AUART_CTRL2_RXE;

	/* figure out the stop bits requested */
	if (cflag & CSTOPB)
		ctrl |= AUART_LINECTRL_STP2;

	/* figure out the hardware flow control settings */
	if (cflag & CRTSCTS) {
		/*
		 * The DMA has a bug(see errata:2836) in mx23.
		 * So we can not implement the DMA for auart in mx23,
		 * we can only implement the DMA support for auart
		 * in mx28.
		 */
		if (is_imx28_auart(s) && (s->flags & MXS_AUART_DMA_CONFIG)) {
			if (!mxs_auart_dma_init(s))
				/* enable DMA tranfer */
				ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE
				       | AUART_CTRL2_DMAONERR;
		}
		ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
	} else {
		ctrl2 &= ~(AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN);
	}

	/* set baud rate */
	baud = uart_get_baud_rate(u, termios, old, 0, u->uartclk);
	div = u->uartclk * 32 / baud;
	ctrl |= AUART_LINECTRL_BAUD_DIVFRAC(div & 0x3F);
	ctrl |= AUART_LINECTRL_BAUD_DIVINT(div >> 6);

	writel(ctrl, u->membase + AUART_LINECTRL);
	writel(ctrl2, u->membase + AUART_CTRL2);

	uart_update_timeout(u, termios->c_cflag, baud);

	/* prepare for the DMA RX. */
	if (auart_dma_enabled(s) &&
		!test_and_set_bit(MXS_AUART_DMA_RX_READY, &s->flags)) {
		if (!mxs_auart_dma_prep_rx(s)) {
			/* Disable the normal RX interrupt. */
			writel(AUART_INTR_RXIEN | AUART_INTR_RTIEN,
					u->membase + AUART_INTR_CLR);
		} else {
			mxs_auart_dma_exit(s);
			dev_err(s->dev, "We can not start up the DMA.\n");
		}
	}
}

static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
{
	u32 istatus, istat;
	struct mxs_auart_port *s = context;
	u32 stat = readl(s->port.membase + AUART_STAT);

	istatus = istat = readl(s->port.membase + AUART_INTR);

	if (istat & AUART_INTR_CTSMIS) {
		uart_handle_cts_change(&s->port, stat & AUART_STAT_CTS);
		writel(AUART_INTR_CTSMIS,
				s->port.membase + AUART_INTR_CLR);
		istat &= ~AUART_INTR_CTSMIS;
	}

	if (istat & (AUART_INTR_RTIS | AUART_INTR_RXIS)) {
		if (!auart_dma_enabled(s))
			mxs_auart_rx_chars(s);
		istat &= ~(AUART_INTR_RTIS | AUART_INTR_RXIS);
	}

	if (istat & AUART_INTR_TXIS) {
		mxs_auart_tx_chars(s);
		istat &= ~AUART_INTR_TXIS;
	}

	writel(istatus & (AUART_INTR_RTIS
		| AUART_INTR_TXIS
		| AUART_INTR_RXIS
		| AUART_INTR_CTSMIS),
			s->port.membase + AUART_INTR_CLR);

	return IRQ_HANDLED;
}

static void mxs_auart_reset(struct uart_port *u)
{
	int i;
	unsigned int reg;

	writel(AUART_CTRL0_SFTRST, u->membase + AUART_CTRL0_CLR);

	for (i = 0; i < 10000; i++) {
		reg = readl(u->membase + AUART_CTRL0);
		if (!(reg & AUART_CTRL0_SFTRST))
			break;
		udelay(3);
	}
	writel(AUART_CTRL0_CLKGATE, u->membase + AUART_CTRL0_CLR);
}

static int mxs_auart_startup(struct uart_port *u)
{
	struct mxs_auart_port *s = to_auart_port(u);

	clk_prepare_enable(s->clk);

	writel(AUART_CTRL0_CLKGATE, u->membase + AUART_CTRL0_CLR);

	writel(AUART_CTRL2_UARTEN, u->membase + AUART_CTRL2_SET);

	writel(AUART_INTR_RXIEN | AUART_INTR_RTIEN | AUART_INTR_CTSMIEN,
			u->membase + AUART_INTR);

	/*
	 * Enable fifo so all four bytes of a DMA word are written to
	 * output (otherwise, only the LSB is written, ie. 1 in 4 bytes)
	 */
	writel(AUART_LINECTRL_FEN, u->membase + AUART_LINECTRL_SET);

	return 0;
}

static void mxs_auart_shutdown(struct uart_port *u)
{
	struct mxs_auart_port *s = to_auart_port(u);

	if (auart_dma_enabled(s))
		mxs_auart_dma_exit(s);

	writel(AUART_CTRL2_UARTEN, u->membase + AUART_CTRL2_CLR);

	writel(AUART_INTR_RXIEN | AUART_INTR_RTIEN | AUART_INTR_CTSMIEN,
			u->membase + AUART_INTR_CLR);

	writel(AUART_CTRL0_CLKGATE, u->membase + AUART_CTRL0_SET);

	clk_disable_unprepare(s->clk);
}

static unsigned int mxs_auart_tx_empty(struct uart_port *u)
{
	if (readl(u->membase + AUART_STAT) & AUART_STAT_TXFE)
		return TIOCSER_TEMT;
	else
		return 0;
}

static void mxs_auart_start_tx(struct uart_port *u)
{
	struct mxs_auart_port *s = to_auart_port(u);

	/* enable transmitter */
	writel(AUART_CTRL2_TXE, u->membase + AUART_CTRL2_SET);

	mxs_auart_tx_chars(s);
}

static void mxs_auart_stop_tx(struct uart_port *u)
{
	writel(AUART_CTRL2_TXE, u->membase + AUART_CTRL2_CLR);
}

static void mxs_auart_stop_rx(struct uart_port *u)
{
	writel(AUART_CTRL2_RXE, u->membase + AUART_CTRL2_CLR);
}

static void mxs_auart_break_ctl(struct uart_port *u, int ctl)
{
	if (ctl)
		writel(AUART_LINECTRL_BRK,
			     u->membase + AUART_LINECTRL_SET);
	else
		writel(AUART_LINECTRL_BRK,
			     u->membase + AUART_LINECTRL_CLR);
}

static void mxs_auart_enable_ms(struct uart_port *port)
{
	/* just empty */
}

static struct uart_ops mxs_auart_ops = {
	.tx_empty       = mxs_auart_tx_empty,
	.start_tx       = mxs_auart_start_tx,
	.stop_tx	= mxs_auart_stop_tx,
	.stop_rx	= mxs_auart_stop_rx,
	.enable_ms      = mxs_auart_enable_ms,
	.break_ctl      = mxs_auart_break_ctl,
	.set_mctrl	= mxs_auart_set_mctrl,
	.get_mctrl      = mxs_auart_get_mctrl,
	.startup	= mxs_auart_startup,
	.shutdown       = mxs_auart_shutdown,
	.set_termios    = mxs_auart_settermios,
	.type	   	= mxs_auart_type,
	.release_port   = mxs_auart_release_port,
	.request_port   = mxs_auart_request_port,
	.config_port    = mxs_auart_config_port,
	.verify_port    = mxs_auart_verify_port,
};

static struct mxs_auart_port *auart_port[MXS_AUART_PORTS];

#ifdef CONFIG_SERIAL_MXS_AUART_CONSOLE
static void mxs_auart_console_putchar(struct uart_port *port, int ch)
{
	unsigned int to = 1000;

	while (readl(port->membase + AUART_STAT) & AUART_STAT_TXFF) {
		if (!to--)
			break;
		udelay(1);
	}

	writel(ch, port->membase + AUART_DATA);
}

static void
auart_console_write(struct console *co, const char *str, unsigned int count)
{
	struct mxs_auart_port *s;
	struct uart_port *port;
	unsigned int old_ctrl0, old_ctrl2;
	unsigned int to = 1000;

	if (co->index >	MXS_AUART_PORTS || co->index < 0)
		return;

	s = auart_port[co->index];
	port = &s->port;

	clk_enable(s->clk);

	/* First save the CR then disable the interrupts */
	old_ctrl2 = readl(port->membase + AUART_CTRL2);
	old_ctrl0 = readl(port->membase + AUART_CTRL0);

	writel(AUART_CTRL0_CLKGATE,
		     port->membase + AUART_CTRL0_CLR);
	writel(AUART_CTRL2_UARTEN | AUART_CTRL2_TXE,
		     port->membase + AUART_CTRL2_SET);

	uart_console_write(port, str, count, mxs_auart_console_putchar);

	/*
	 * Finally, wait for transmitter to become empty
	 * and restore the TCR
	 */
	while (readl(port->membase + AUART_STAT) & AUART_STAT_BUSY) {
		if (!to--)
			break;
		udelay(1);
	}

	writel(old_ctrl0, port->membase + AUART_CTRL0);
	writel(old_ctrl2, port->membase + AUART_CTRL2);

	clk_disable(s->clk);
}

static void __init
auart_console_get_options(struct uart_port *port, int *baud,
			  int *parity, int *bits)
{
	unsigned int lcr_h, quot;

	if (!(readl(port->membase + AUART_CTRL2) & AUART_CTRL2_UARTEN))
		return;

	lcr_h = readl(port->membase + AUART_LINECTRL);

	*parity = 'n';
	if (lcr_h & AUART_LINECTRL_PEN) {
		if (lcr_h & AUART_LINECTRL_EPS)
			*parity = 'e';
		else
			*parity = 'o';
	}

	if ((lcr_h & AUART_LINECTRL_WLEN_MASK) == AUART_LINECTRL_WLEN(2))
		*bits = 7;
	else
		*bits = 8;

	quot = ((readl(port->membase + AUART_LINECTRL)
			& AUART_LINECTRL_BAUD_DIVINT_MASK))
			    >> (AUART_LINECTRL_BAUD_DIVINT_SHIFT - 6);
	quot |= ((readl(port->membase + AUART_LINECTRL)
			& AUART_LINECTRL_BAUD_DIVFRAC_MASK))
				>> AUART_LINECTRL_BAUD_DIVFRAC_SHIFT;
	if (quot == 0)
		quot = 1;

	*baud = (port->uartclk << 2) / quot;
}

static int __init
auart_console_setup(struct console *co, char *options)
{
	struct mxs_auart_port *s;
	int baud = 9600;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';
	int ret;

	/*
	 * Check whether an invalid uart number has been specified, and
	 * if so, search for the first available port that does have
	 * console support.
	 */
	if (co->index == -1 || co->index >= ARRAY_SIZE(auart_port))
		co->index = 0;
	s = auart_port[co->index];
	if (!s)
		return -ENODEV;

	clk_prepare_enable(s->clk);

	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);
	else
		auart_console_get_options(&s->port, &baud, &parity, &bits);

	ret = uart_set_options(&s->port, co, baud, parity, bits, flow);

	clk_disable_unprepare(s->clk);

	return ret;
}

static struct console auart_console = {
	.name		= "ttyAPP",
	.write		= auart_console_write,
	.device		= uart_console_device,
	.setup		= auart_console_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &auart_driver,
};
#endif

static struct uart_driver auart_driver = {
	.owner		= THIS_MODULE,
	.driver_name	= "ttyAPP",
	.dev_name	= "ttyAPP",
	.major		= 0,
	.minor		= 0,
	.nr		= MXS_AUART_PORTS,
#ifdef CONFIG_SERIAL_MXS_AUART_CONSOLE
	.cons =		&auart_console,
#endif
};

/*
 * This function returns 1 if pdev isn't a device instatiated by dt, 0 if it
 * could successfully get all information from dt or a negative errno.
 */
static int serial_mxs_probe_dt(struct mxs_auart_port *s,
		struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	u32 dma_channel[2];
	int ret;

	if (!np)
		/* no device tree device */
		return 1;

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

	s->dma_irq_rx = platform_get_irq(pdev, 1);
	s->dma_irq_tx = platform_get_irq(pdev, 2);

	ret = of_property_read_u32_array(np, "fsl,auart-dma-channel",
					dma_channel, 2);
	if (ret == 0) {
		s->dma_channel_rx = dma_channel[0];
		s->dma_channel_tx = dma_channel[1];

		s->flags |= MXS_AUART_DMA_CONFIG;
	} else {
		s->dma_channel_rx = -1;
		s->dma_channel_tx = -1;
	}
	return 0;
}

static int mxs_auart_probe(struct platform_device *pdev)
{
	const struct of_device_id *of_id =
			of_match_device(mxs_auart_dt_ids, &pdev->dev);
	struct mxs_auart_port *s;
	u32 version;
	int ret = 0;
	struct resource *r;
	struct pinctrl *pinctrl;

	s = kzalloc(sizeof(struct mxs_auart_port), GFP_KERNEL);
	if (!s) {
		ret = -ENOMEM;
		goto out;
	}

	ret = serial_mxs_probe_dt(s, pdev);
	if (ret > 0)
		s->port.line = pdev->id < 0 ? 0 : pdev->id;
	else if (ret < 0)
		goto out_free;

	pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
	if (IS_ERR(pinctrl)) {
		ret = PTR_ERR(pinctrl);
		goto out_free;
	}

	if (of_id) {
		pdev->id_entry = of_id->data;
		s->devtype = pdev->id_entry->driver_data;
	}

	s->clk = clk_get(&pdev->dev, NULL);
	if (IS_ERR(s->clk)) {
		ret = PTR_ERR(s->clk);
		goto out_free;
	}

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!r) {
		ret = -ENXIO;
		goto out_free_clk;
	}

	s->port.mapbase = r->start;
	s->port.membase = ioremap(r->start, resource_size(r));
	s->port.ops = &mxs_auart_ops;
	s->port.iotype = UPIO_MEM;
	s->port.fifosize = 16;
	s->port.uartclk = clk_get_rate(s->clk);
	s->port.type = PORT_IMX;
	s->port.dev = s->dev = get_device(&pdev->dev);

	s->ctrl = 0;

	s->irq = platform_get_irq(pdev, 0);
	s->port.irq = s->irq;
	ret = request_irq(s->irq, mxs_auart_irq_handle, 0, dev_name(&pdev->dev), s);
	if (ret)
		goto out_free_clk;

	platform_set_drvdata(pdev, s);

	auart_port[s->port.line] = s;

	mxs_auart_reset(&s->port);

	ret = uart_add_one_port(&auart_driver, &s->port);
	if (ret)
		goto out_free_irq;

	version = readl(s->port.membase + AUART_VERSION);
	dev_info(&pdev->dev, "Found APPUART %d.%d.%d\n",
	       (version >> 24) & 0xff,
	       (version >> 16) & 0xff, version & 0xffff);

	return 0;

out_free_irq:
	auart_port[pdev->id] = NULL;
	free_irq(s->irq, s);
out_free_clk:
	put_device(s->dev);
	clk_put(s->clk);
out_free:
	kfree(s);
out:
	return ret;
}

static int mxs_auart_remove(struct platform_device *pdev)
{
	struct mxs_auart_port *s = platform_get_drvdata(pdev);

	uart_remove_one_port(&auart_driver, &s->port);

	auart_port[pdev->id] = NULL;

	put_device(s->dev);
	clk_put(s->clk);
	free_irq(s->irq, s);
	kfree(s);

	return 0;
}

static struct platform_driver mxs_auart_driver = {
	.probe = mxs_auart_probe,
	.remove = mxs_auart_remove,
	.driver = {
		.name = "mxs-auart",
		.owner = THIS_MODULE,
		.of_match_table = mxs_auart_dt_ids,
	},
};

static int __init mxs_auart_init(void)
{
	int r;

	r = uart_register_driver(&auart_driver);
	if (r)
		goto out;

	r = platform_driver_register(&mxs_auart_driver);
	if (r)
		goto out_err;

	return 0;
out_err:
	uart_unregister_driver(&auart_driver);
out:
	return r;
}

static void __exit mxs_auart_exit(void)
{
	platform_driver_unregister(&mxs_auart_driver);
	uart_unregister_driver(&auart_driver);
}

module_init(mxs_auart_init);
module_exit(mxs_auart_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Freescale MXS application uart driver");
MODULE_ALIAS("platform:mxs-auart");