summaryrefslogtreecommitdiff
path: root/drivers/serial/sb1250-duart.c
blob: 1d9d7285172a46cf4662ef48bf0761c396d04894 (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
/*
 *	drivers/serial/sb1250-duart.c
 *
 *	Support for the asynchronous serial interface (DUART) included
 *	in the BCM1250 and derived System-On-a-Chip (SOC) devices.
 *
 *	Copyright (c) 2007  Maciej W. Rozycki
 *
 *	Derived from drivers/char/sb1250_duart.c for which the following
 *	copyright applies:
 *
 *	Copyright (c) 2000, 2001, 2002, 2003, 2004  Broadcom Corporation
 *
 *	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.
 *
 *	References:
 *
 *	"BCM1250/BCM1125/BCM1125H User Manual", Broadcom Corporation
 */

#if defined(CONFIG_SERIAL_SB1250_DUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/console.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <linux/spinlock.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/types.h>

#include <asm/atomic.h>
#include <asm/io.h>
#include <asm/war.h>

#include <asm/sibyte/sb1250.h>
#include <asm/sibyte/sb1250_uart.h>
#include <asm/sibyte/swarm.h>


#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
#include <asm/sibyte/bcm1480_regs.h>
#include <asm/sibyte/bcm1480_int.h>

#define SBD_CHANREGS(line)	A_BCM1480_DUART_CHANREG((line), 0)
#define SBD_CTRLREGS(line)	A_BCM1480_DUART_CTRLREG((line), 0)
#define SBD_INT(line)		(K_BCM1480_INT_UART_0 + (line))

#elif defined(CONFIG_SIBYTE_SB1250) || defined(CONFIG_SIBYTE_BCM112X)
#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_int.h>

#define SBD_CHANREGS(line)	A_DUART_CHANREG((line), 0)
#define SBD_CTRLREGS(line)	A_DUART_CTRLREG(0)
#define SBD_INT(line)		(K_INT_UART_0 + (line))

#else
#error invalid SB1250 UART configuration

#endif


MODULE_AUTHOR("Maciej W. Rozycki <macro@linux-mips.org>");
MODULE_DESCRIPTION("BCM1xxx on-chip DUART serial driver");
MODULE_LICENSE("GPL");


#define DUART_MAX_CHIP 2
#define DUART_MAX_SIDE 2

/*
 * Per-port state.
 */
struct sbd_port {
	struct sbd_duart	*duart;
	struct uart_port	port;
	unsigned char __iomem	*memctrl;
	int			tx_stopped;
	int			initialised;
};

/*
 * Per-DUART state for the shared register space.
 */
struct sbd_duart {
	struct sbd_port		sport[2];
	unsigned long		mapctrl;
	atomic_t		map_guard;
};

#define to_sport(uport) container_of(uport, struct sbd_port, port)

static struct sbd_duart sbd_duarts[DUART_MAX_CHIP];

#define __unused __attribute__((__unused__))


/*
 * Reading and writing SB1250 DUART registers.
 *
 * There are three register spaces: two per-channel ones and
 * a shared one.  We have to define accessors appropriately.
 * All registers are 64-bit and all but the Baud Rate Clock
 * registers only define 8 least significant bits.  There is
 * also a workaround to take into account.  Raw accessors use
 * the full register width, but cooked ones truncate it
 * intentionally so that the rest of the driver does not care.
 */
static u64 __read_sbdchn(struct sbd_port *sport, int reg)
{
	void __iomem *csr = sport->port.membase + reg;

	return __raw_readq(csr);
}

static u64 __read_sbdshr(struct sbd_port *sport, int reg)
{
	void __iomem *csr = sport->memctrl + reg;

	return __raw_readq(csr);
}

static void __write_sbdchn(struct sbd_port *sport, int reg, u64 value)
{
	void __iomem *csr = sport->port.membase + reg;

	__raw_writeq(value, csr);
}

static void __write_sbdshr(struct sbd_port *sport, int reg, u64 value)
{
	void __iomem *csr = sport->memctrl + reg;

	__raw_writeq(value, csr);
}

/*
 * In bug 1956, we get glitches that can mess up uart registers.  This
 * "read-mode-reg after any register access" is an accepted workaround.
 */
static void __war_sbd1956(struct sbd_port *sport)
{
	__read_sbdchn(sport, R_DUART_MODE_REG_1);
	__read_sbdchn(sport, R_DUART_MODE_REG_2);
}

static unsigned char read_sbdchn(struct sbd_port *sport, int reg)
{
	unsigned char retval;

	retval = __read_sbdchn(sport, reg);
	if (SIBYTE_1956_WAR)
		__war_sbd1956(sport);
	return retval;
}

static unsigned char read_sbdshr(struct sbd_port *sport, int reg)
{
	unsigned char retval;

	retval = __read_sbdshr(sport, reg);
	if (SIBYTE_1956_WAR)
		__war_sbd1956(sport);
	return retval;
}

static void write_sbdchn(struct sbd_port *sport, int reg, unsigned int value)
{
	__write_sbdchn(sport, reg, value);
	if (SIBYTE_1956_WAR)
		__war_sbd1956(sport);
}

static void write_sbdshr(struct sbd_port *sport, int reg, unsigned int value)
{
	__write_sbdshr(sport, reg, value);
	if (SIBYTE_1956_WAR)
		__war_sbd1956(sport);
}


static int sbd_receive_ready(struct sbd_port *sport)
{
	return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_RX_RDY;
}

static int sbd_receive_drain(struct sbd_port *sport)
{
	int loops = 10000;

	while (sbd_receive_ready(sport) && loops--)
		read_sbdchn(sport, R_DUART_RX_HOLD);
	return loops;
}

static int __unused sbd_transmit_ready(struct sbd_port *sport)
{
	return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_TX_RDY;
}

static int __unused sbd_transmit_drain(struct sbd_port *sport)
{
	int loops = 10000;

	while (!sbd_transmit_ready(sport) && loops--)
		udelay(2);
	return loops;
}

static int sbd_transmit_empty(struct sbd_port *sport)
{
	return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_TX_EMT;
}

static int sbd_line_drain(struct sbd_port *sport)
{
	int loops = 10000;

	while (!sbd_transmit_empty(sport) && loops--)
		udelay(2);
	return loops;
}


static unsigned int sbd_tx_empty(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);

	return sbd_transmit_empty(sport) ? TIOCSER_TEMT : 0;
}

static unsigned int sbd_get_mctrl(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);
	unsigned int mctrl, status;

	status = read_sbdshr(sport, R_DUART_IN_PORT);
	status >>= (uport->line) % 2;
	mctrl = (!(status & M_DUART_IN_PIN0_VAL) ? TIOCM_CTS : 0) |
		(!(status & M_DUART_IN_PIN4_VAL) ? TIOCM_CAR : 0) |
		(!(status & M_DUART_RIN0_PIN) ? TIOCM_RNG : 0) |
		(!(status & M_DUART_IN_PIN2_VAL) ? TIOCM_DSR : 0);
	return mctrl;
}

static void sbd_set_mctrl(struct uart_port *uport, unsigned int mctrl)
{
	struct sbd_port *sport = to_sport(uport);
	unsigned int clr = 0, set = 0, mode2;

	if (mctrl & TIOCM_DTR)
		set |= M_DUART_SET_OPR2;
	else
		clr |= M_DUART_CLR_OPR2;
	if (mctrl & TIOCM_RTS)
		set |= M_DUART_SET_OPR0;
	else
		clr |= M_DUART_CLR_OPR0;
	clr <<= (uport->line) % 2;
	set <<= (uport->line) % 2;

	mode2 = read_sbdchn(sport, R_DUART_MODE_REG_2);
	mode2 &= ~M_DUART_CHAN_MODE;
	if (mctrl & TIOCM_LOOP)
		mode2 |= V_DUART_CHAN_MODE_LCL_LOOP;
	else
		mode2 |= V_DUART_CHAN_MODE_NORMAL;

	write_sbdshr(sport, R_DUART_CLEAR_OPR, clr);
	write_sbdshr(sport, R_DUART_SET_OPR, set);
	write_sbdchn(sport, R_DUART_MODE_REG_2, mode2);
}

static void sbd_stop_tx(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);

	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS);
	sport->tx_stopped = 1;
};

static void sbd_start_tx(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);
	unsigned int mask;

	/* Enable tx interrupts.  */
	mask = read_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2));
	mask |= M_DUART_IMR_TX;
	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), mask);

	/* Go!, go!, go!...  */
	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_EN);
	sport->tx_stopped = 0;
};

static void sbd_stop_rx(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);

	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), 0);
};

static void sbd_enable_ms(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);

	write_sbdchn(sport, R_DUART_AUXCTL_X,
		     M_DUART_CIN_CHNG_ENA | M_DUART_CTS_CHNG_ENA);
}

static void sbd_break_ctl(struct uart_port *uport, int break_state)
{
	struct sbd_port *sport = to_sport(uport);

	if (break_state == -1)
		write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_START_BREAK);
	else
		write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_STOP_BREAK);
}


static void sbd_receive_chars(struct sbd_port *sport)
{
	struct uart_port *uport = &sport->port;
	struct uart_icount *icount;
	unsigned int status, ch, flag;
	int count;

	for (count = 16; count; count--) {
		status = read_sbdchn(sport, R_DUART_STATUS);
		if (!(status & M_DUART_RX_RDY))
			break;

		ch = read_sbdchn(sport, R_DUART_RX_HOLD);

		flag = TTY_NORMAL;

		icount = &uport->icount;
		icount->rx++;

		if (unlikely(status &
			     (M_DUART_RCVD_BRK | M_DUART_FRM_ERR |
			      M_DUART_PARITY_ERR | M_DUART_OVRUN_ERR))) {
			if (status & M_DUART_RCVD_BRK) {
				icount->brk++;
				if (uart_handle_break(uport))
					continue;
			} else if (status & M_DUART_FRM_ERR)
				icount->frame++;
			else if (status & M_DUART_PARITY_ERR)
				icount->parity++;
			if (status & M_DUART_OVRUN_ERR)
				icount->overrun++;

			status &= uport->read_status_mask;
			if (status & M_DUART_RCVD_BRK)
				flag = TTY_BREAK;
			else if (status & M_DUART_FRM_ERR)
				flag = TTY_FRAME;
			else if (status & M_DUART_PARITY_ERR)
				flag = TTY_PARITY;
		}

		if (uart_handle_sysrq_char(uport, ch))
			continue;

		uart_insert_char(uport, status, M_DUART_OVRUN_ERR, ch, flag);
	}

	tty_flip_buffer_push(uport->info->tty);
}

static void sbd_transmit_chars(struct sbd_port *sport)
{
	struct uart_port *uport = &sport->port;
	struct circ_buf *xmit = &sport->port.info->xmit;
	unsigned int mask;
	int stop_tx;

	/* XON/XOFF chars.  */
	if (sport->port.x_char) {
		write_sbdchn(sport, R_DUART_TX_HOLD, sport->port.x_char);
		sport->port.icount.tx++;
		sport->port.x_char = 0;
		return;
	}

	/* If nothing to do or stopped or hardware stopped.  */
	stop_tx = (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port));

	/* Send char.  */
	if (!stop_tx) {
		write_sbdchn(sport, R_DUART_TX_HOLD, xmit->buf[xmit->tail]);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		sport->port.icount.tx++;

		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
			uart_write_wakeup(&sport->port);
	}

	/* Are we are done?  */
	if (stop_tx || uart_circ_empty(xmit)) {
		/* Disable tx interrupts.  */
		mask = read_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2));
		mask &= ~M_DUART_IMR_TX;
		write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), mask);
	}
}

static void sbd_status_handle(struct sbd_port *sport)
{
	struct uart_port *uport = &sport->port;
	unsigned int delta;

	delta = read_sbdshr(sport, R_DUART_INCHREG((uport->line) % 2));
	delta >>= (uport->line) % 2;

	if (delta & (M_DUART_IN_PIN0_VAL << S_DUART_IN_PIN_CHNG))
		uart_handle_cts_change(uport, !(delta & M_DUART_IN_PIN0_VAL));

	if (delta & (M_DUART_IN_PIN2_VAL << S_DUART_IN_PIN_CHNG))
		uport->icount.dsr++;

	if (delta & ((M_DUART_IN_PIN2_VAL | M_DUART_IN_PIN0_VAL) <<
		     S_DUART_IN_PIN_CHNG))
		wake_up_interruptible(&uport->info->delta_msr_wait);
}

static irqreturn_t sbd_interrupt(int irq, void *dev_id)
{
	struct sbd_port *sport = dev_id;
	struct uart_port *uport = &sport->port;
	irqreturn_t status = IRQ_NONE;
	unsigned int intstat;
	int count;

	for (count = 16; count; count--) {
		intstat = read_sbdshr(sport,
				      R_DUART_ISRREG((uport->line) % 2));
		intstat &= read_sbdshr(sport,
				       R_DUART_IMRREG((uport->line) % 2));
		intstat &= M_DUART_ISR_ALL;
		if (!intstat)
			break;

		if (intstat & M_DUART_ISR_RX)
			sbd_receive_chars(sport);
		if (intstat & M_DUART_ISR_IN)
			sbd_status_handle(sport);
		if (intstat & M_DUART_ISR_TX)
			sbd_transmit_chars(sport);

		status = IRQ_HANDLED;
	}

	return status;
}


static int sbd_startup(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);
	unsigned int mode1;
	int ret;

	ret = request_irq(sport->port.irq, sbd_interrupt,
			  IRQF_SHARED, "sb1250-duart", sport);
	if (ret)
		return ret;

	/* Clear the receive FIFO.  */
	sbd_receive_drain(sport);

	/* Clear the interrupt registers.  */
	write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_RESET_BREAK_INT);
	read_sbdshr(sport, R_DUART_INCHREG((uport->line) % 2));

	/* Set rx/tx interrupt to FIFO available.  */
	mode1 = read_sbdchn(sport, R_DUART_MODE_REG_1);
	mode1 &= ~(M_DUART_RX_IRQ_SEL_RXFULL | M_DUART_TX_IRQ_SEL_TXEMPT);
	write_sbdchn(sport, R_DUART_MODE_REG_1, mode1);

	/* Disable tx, enable rx.  */
	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS | M_DUART_RX_EN);
	sport->tx_stopped = 1;

	/* Enable interrupts.  */
	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2),
		     M_DUART_IMR_IN | M_DUART_IMR_RX);

	return 0;
}

static void sbd_shutdown(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);

	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS | M_DUART_RX_DIS);
	sport->tx_stopped = 1;
	free_irq(sport->port.irq, sport);
}


static void sbd_init_port(struct sbd_port *sport)
{
	struct uart_port *uport = &sport->port;

	if (sport->initialised)
		return;

	/* There is no DUART reset feature, so just set some sane defaults.  */
	write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_RESET_TX);
	write_sbdchn(sport, R_DUART_CMD, V_DUART_MISC_CMD_RESET_RX);
	write_sbdchn(sport, R_DUART_MODE_REG_1, V_DUART_BITS_PER_CHAR_8);
	write_sbdchn(sport, R_DUART_MODE_REG_2, 0);
	write_sbdchn(sport, R_DUART_FULL_CTL,
		     V_DUART_INT_TIME(0) | V_DUART_SIG_FULL(15));
	write_sbdchn(sport, R_DUART_OPCR_X, 0);
	write_sbdchn(sport, R_DUART_AUXCTL_X, 0);
	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), 0);

	sport->initialised = 1;
}

static void sbd_set_termios(struct uart_port *uport, struct ktermios *termios,
			    struct ktermios *old_termios)
{
	struct sbd_port *sport = to_sport(uport);
	unsigned int mode1 = 0, mode2 = 0, aux = 0;
	unsigned int mode1mask = 0, mode2mask = 0, auxmask = 0;
	unsigned int oldmode1, oldmode2, oldaux;
	unsigned int baud, brg;
	unsigned int command;

	mode1mask |= ~(M_DUART_PARITY_MODE | M_DUART_PARITY_TYPE_ODD |
		       M_DUART_BITS_PER_CHAR);
	mode2mask |= ~M_DUART_STOP_BIT_LEN_2;
	auxmask |= ~M_DUART_CTS_CHNG_ENA;

	/* Byte size.  */
	switch (termios->c_cflag & CSIZE) {
	case CS5:
	case CS6:
		/* Unsupported, leave unchanged.  */
		mode1mask |= M_DUART_PARITY_MODE;
		break;
	case CS7:
		mode1 |= V_DUART_BITS_PER_CHAR_7;
		break;
	case CS8:
	default:
		mode1 |= V_DUART_BITS_PER_CHAR_8;
		break;
	}

	/* Parity and stop bits.  */
	if (termios->c_cflag & CSTOPB)
		mode2 |= M_DUART_STOP_BIT_LEN_2;
	else
		mode2 |= M_DUART_STOP_BIT_LEN_1;
	if (termios->c_cflag & PARENB)
		mode1 |= V_DUART_PARITY_MODE_ADD;
	else
		mode1 |= V_DUART_PARITY_MODE_NONE;
	if (termios->c_cflag & PARODD)
		mode1 |= M_DUART_PARITY_TYPE_ODD;
	else
		mode1 |= M_DUART_PARITY_TYPE_EVEN;

	baud = uart_get_baud_rate(uport, termios, old_termios, 1200, 5000000);
	brg = V_DUART_BAUD_RATE(baud);
	/* The actual lower bound is 1221bps, so compensate.  */
	if (brg > M_DUART_CLK_COUNTER)
		brg = M_DUART_CLK_COUNTER;

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

	uport->read_status_mask = M_DUART_OVRUN_ERR;
	if (termios->c_iflag & INPCK)
		uport->read_status_mask |= M_DUART_FRM_ERR |
					   M_DUART_PARITY_ERR;
	if (termios->c_iflag & (BRKINT | PARMRK))
		uport->read_status_mask |= M_DUART_RCVD_BRK;

	uport->ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
		uport->ignore_status_mask |= M_DUART_FRM_ERR |
					     M_DUART_PARITY_ERR;
	if (termios->c_iflag & IGNBRK) {
		uport->ignore_status_mask |= M_DUART_RCVD_BRK;
		if (termios->c_iflag & IGNPAR)
			uport->ignore_status_mask |= M_DUART_OVRUN_ERR;
	}

	if (termios->c_cflag & CREAD)
		command = M_DUART_RX_EN;
	else
		command = M_DUART_RX_DIS;

	if (termios->c_cflag & CRTSCTS)
		aux |= M_DUART_CTS_CHNG_ENA;
	else
		aux &= ~M_DUART_CTS_CHNG_ENA;

	spin_lock(&uport->lock);

	if (sport->tx_stopped)
		command |= M_DUART_TX_DIS;
	else
		command |= M_DUART_TX_EN;

	oldmode1 = read_sbdchn(sport, R_DUART_MODE_REG_1) & mode1mask;
	oldmode2 = read_sbdchn(sport, R_DUART_MODE_REG_2) & mode2mask;
	oldaux = read_sbdchn(sport, R_DUART_AUXCTL_X) & auxmask;

	if (!sport->tx_stopped)
		sbd_line_drain(sport);
	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS | M_DUART_RX_DIS);

	write_sbdchn(sport, R_DUART_MODE_REG_1, mode1 | oldmode1);
	write_sbdchn(sport, R_DUART_MODE_REG_2, mode2 | oldmode2);
	write_sbdchn(sport, R_DUART_CLK_SEL, brg);
	write_sbdchn(sport, R_DUART_AUXCTL_X, aux | oldaux);

	write_sbdchn(sport, R_DUART_CMD, command);

	spin_unlock(&uport->lock);
}


static const char *sbd_type(struct uart_port *uport)
{
	return "SB1250 DUART";
}

static void sbd_release_port(struct uart_port *uport)
{
	struct sbd_port *sport = to_sport(uport);
	struct sbd_duart *duart = sport->duart;
	int map_guard;

	iounmap(sport->memctrl);
	sport->memctrl = NULL;
	iounmap(uport->membase);
	uport->membase = NULL;

	map_guard = atomic_add_return(-1, &duart->map_guard);
	if (!map_guard)
		release_mem_region(duart->mapctrl, DUART_CHANREG_SPACING);
	release_mem_region(uport->mapbase, DUART_CHANREG_SPACING);
}

static int sbd_map_port(struct uart_port *uport)
{
	static const char *err = KERN_ERR "sbd: Cannot map MMIO\n";
	struct sbd_port *sport = to_sport(uport);
	struct sbd_duart *duart = sport->duart;

	if (!uport->membase)
		uport->membase = ioremap_nocache(uport->mapbase,
						 DUART_CHANREG_SPACING);
	if (!uport->membase) {
		printk(err);
		return -ENOMEM;
	}

	if (!sport->memctrl)
		sport->memctrl = ioremap_nocache(duart->mapctrl,
						 DUART_CHANREG_SPACING);
	if (!sport->memctrl) {
		printk(err);
		iounmap(uport->membase);
		uport->membase = NULL;
		return -ENOMEM;
	}

	return 0;
}

static int sbd_request_port(struct uart_port *uport)
{
	static const char *err = KERN_ERR
				 "sbd: Unable to reserve MMIO resource\n";
	struct sbd_duart *duart = to_sport(uport)->duart;
	int map_guard;
	int ret = 0;

	if (!request_mem_region(uport->mapbase, DUART_CHANREG_SPACING,
				"sb1250-duart")) {
		printk(err);
		return -EBUSY;
	}
	map_guard = atomic_add_return(1, &duart->map_guard);
	if (map_guard == 1) {
		if (!request_mem_region(duart->mapctrl, DUART_CHANREG_SPACING,
					"sb1250-duart")) {
			atomic_add(-1, &duart->map_guard);
			printk(err);
			ret = -EBUSY;
		}
	}
	if (!ret) {
		ret = sbd_map_port(uport);
		if (ret) {
			map_guard = atomic_add_return(-1, &duart->map_guard);
			if (!map_guard)
				release_mem_region(duart->mapctrl,
						   DUART_CHANREG_SPACING);
		}
	}
	if (ret) {
		release_mem_region(uport->mapbase, DUART_CHANREG_SPACING);
		return ret;
	}
	return 0;
}

static void sbd_config_port(struct uart_port *uport, int flags)
{
	struct sbd_port *sport = to_sport(uport);

	if (flags & UART_CONFIG_TYPE) {
		if (sbd_request_port(uport))
			return;

		uport->type = PORT_SB1250_DUART;

		sbd_init_port(sport);
	}
}

static int sbd_verify_port(struct uart_port *uport, struct serial_struct *ser)
{
	int ret = 0;

	if (ser->type != PORT_UNKNOWN && ser->type != PORT_SB1250_DUART)
		ret = -EINVAL;
	if (ser->irq != uport->irq)
		ret = -EINVAL;
	if (ser->baud_base != uport->uartclk / 16)
		ret = -EINVAL;
	return ret;
}


static struct uart_ops sbd_ops = {
	.tx_empty	= sbd_tx_empty,
	.set_mctrl	= sbd_set_mctrl,
	.get_mctrl	= sbd_get_mctrl,
	.stop_tx	= sbd_stop_tx,
	.start_tx	= sbd_start_tx,
	.stop_rx	= sbd_stop_rx,
	.enable_ms	= sbd_enable_ms,
	.break_ctl	= sbd_break_ctl,
	.startup	= sbd_startup,
	.shutdown	= sbd_shutdown,
	.set_termios	= sbd_set_termios,
	.type		= sbd_type,
	.release_port	= sbd_release_port,
	.request_port	= sbd_request_port,
	.config_port	= sbd_config_port,
	.verify_port	= sbd_verify_port,
};

/* Initialize SB1250 DUART port structures.  */
static void __init sbd_probe_duarts(void)
{
	static int probed;
	int chip, side;
	int max_lines, line;

	if (probed)
		return;

	/* Set the number of available units based on the SOC type.  */
	switch (soc_type) {
	case K_SYS_SOC_TYPE_BCM1x55:
	case K_SYS_SOC_TYPE_BCM1x80:
		max_lines = 4;
		break;
	default:
		/* Assume at least two serial ports at the normal address.  */
		max_lines = 2;
		break;
	}

	probed = 1;

	for (chip = 0, line = 0; chip < DUART_MAX_CHIP && line < max_lines;
	     chip++) {
		sbd_duarts[chip].mapctrl = SBD_CTRLREGS(line);

		for (side = 0; side < DUART_MAX_SIDE && line < max_lines;
		     side++, line++) {
			struct sbd_port *sport = &sbd_duarts[chip].sport[side];
			struct uart_port *uport = &sport->port;

			sport->duart	= &sbd_duarts[chip];

			uport->irq	= SBD_INT(line);
			uport->uartclk	= 100000000 / 20 * 16;
			uport->fifosize	= 16;
			uport->iotype	= UPIO_MEM;
			uport->flags	= UPF_BOOT_AUTOCONF;
			uport->ops	= &sbd_ops;
			uport->line	= line;
			uport->mapbase	= SBD_CHANREGS(line);
		}
	}
}


#ifdef CONFIG_SERIAL_SB1250_DUART_CONSOLE
/*
 * Serial console stuff.  Very basic, polling driver for doing serial
 * console output.  The console_sem is held by the caller, so we
 * shouldn't be interrupted for more console activity.
 */
static void sbd_console_putchar(struct uart_port *uport, int ch)
{
	struct sbd_port *sport = to_sport(uport);

	sbd_transmit_drain(sport);
	write_sbdchn(sport, R_DUART_TX_HOLD, ch);
}

static void sbd_console_write(struct console *co, const char *s,
			      unsigned int count)
{
	int chip = co->index / DUART_MAX_SIDE;
	int side = co->index % DUART_MAX_SIDE;
	struct sbd_port *sport = &sbd_duarts[chip].sport[side];
	struct uart_port *uport = &sport->port;
	unsigned long flags;
	unsigned int mask;

	/* Disable transmit interrupts and enable the transmitter. */
	spin_lock_irqsave(&uport->lock, flags);
	mask = read_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2));
	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2),
		     mask & ~M_DUART_IMR_TX);
	write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_EN);
	spin_unlock_irqrestore(&uport->lock, flags);

	uart_console_write(&sport->port, s, count, sbd_console_putchar);

	/* Restore transmit interrupts and the transmitter enable. */
	spin_lock_irqsave(&uport->lock, flags);
	sbd_line_drain(sport);
	if (sport->tx_stopped)
		write_sbdchn(sport, R_DUART_CMD, M_DUART_TX_DIS);
	write_sbdshr(sport, R_DUART_IMRREG((uport->line) % 2), mask);
	spin_unlock_irqrestore(&uport->lock, flags);
}

static int __init sbd_console_setup(struct console *co, char *options)
{
	int chip = co->index / DUART_MAX_SIDE;
	int side = co->index % DUART_MAX_SIDE;
	struct sbd_port *sport = &sbd_duarts[chip].sport[side];
	struct uart_port *uport = &sport->port;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';
	int ret;

	if (!sport->duart)
		return -ENXIO;

	ret = sbd_map_port(uport);
	if (ret)
		return ret;

	sbd_init_port(sport);

	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);
	return uart_set_options(uport, co, baud, parity, bits, flow);
}

static struct uart_driver sbd_reg;
static struct console sbd_console = {
	.name	= "duart",
	.write	= sbd_console_write,
	.device	= uart_console_device,
	.setup	= sbd_console_setup,
	.flags	= CON_PRINTBUFFER,
	.index	= -1,
	.data	= &sbd_reg
};

static int __init sbd_serial_console_init(void)
{
	sbd_probe_duarts();
	register_console(&sbd_console);

	return 0;
}

console_initcall(sbd_serial_console_init);

#define SERIAL_SB1250_DUART_CONSOLE	&sbd_console
#else
#define SERIAL_SB1250_DUART_CONSOLE	NULL
#endif /* CONFIG_SERIAL_SB1250_DUART_CONSOLE */


static struct uart_driver sbd_reg = {
	.owner		= THIS_MODULE,
	.driver_name	= "serial",
	.dev_name	= "duart",
	.major		= TTY_MAJOR,
	.minor		= SB1250_DUART_MINOR_BASE,
	.nr		= DUART_MAX_CHIP * DUART_MAX_SIDE,
	.cons		= SERIAL_SB1250_DUART_CONSOLE,
};

/* Set up the driver and register it.  */
static int __init sbd_init(void)
{
	int i, ret;

	sbd_probe_duarts();

	ret = uart_register_driver(&sbd_reg);
	if (ret)
		return ret;

	for (i = 0; i < DUART_MAX_CHIP * DUART_MAX_SIDE; i++) {
		struct sbd_duart *duart = &sbd_duarts[i / DUART_MAX_SIDE];
		struct sbd_port *sport = &duart->sport[i % DUART_MAX_SIDE];
		struct uart_port *uport = &sport->port;

		if (sport->duart)
			uart_add_one_port(&sbd_reg, uport);
	}

	return 0;
}

/* Unload the driver.  Unregister stuff, get ready to go away.  */
static void __exit sbd_exit(void)
{
	int i;

	for (i = DUART_MAX_CHIP * DUART_MAX_SIDE - 1; i >= 0; i--) {
		struct sbd_duart *duart = &sbd_duarts[i / DUART_MAX_SIDE];
		struct sbd_port *sport = &duart->sport[i % DUART_MAX_SIDE];
		struct uart_port *uport = &sport->port;

		if (sport->duart)
			uart_remove_one_port(&sbd_reg, uport);
	}

	uart_unregister_driver(&sbd_reg);
}

module_init(sbd_init);
module_exit(sbd_exit);