Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  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
/*	$NetBSD: zs.c,v 1.75 2015/10/30 16:21:46 tsutsui Exp $	*/

/*-
 * Copyright (c) 1996 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Gordon W. Ross.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Zilog Z8530 Dual UART driver (machine-dependent part)
 *
 * Runs two serial lines per chip using slave drivers.
 * Plain tty/async lines use the zs_async slave.
 * Sun keyboard/mouse uses the zs_kbd/zs_ms slaves.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: zs.c,v 1.75 2015/10/30 16:21:46 tsutsui Exp $");

#include "opt_ddb.h"
#include "opt_kgdb.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/tty.h>
#include <sys/time.h>
#include <sys/syslog.h>
#include <sys/intr.h>

#include <machine/autoconf.h>
#include <machine/openfirm.h>
#include <machine/cpu.h>
#include <machine/eeprom.h>
#include <machine/psl.h>
#include <machine/z8530var.h>

#include <dev/cons.h>
#include <dev/ic/z8530reg.h>
#include <dev/sun/kbd_ms_ttyvar.h>
#include <ddb/db_output.h>

#include <dev/sbus/sbusvar.h>
#include <sparc64/dev/fhcvar.h>
#include <sparc64/dev/cons.h>

#include "ioconf.h"
#include "kbd.h"	/* NKBD */
#include "ms.h"		/* NMS */
#include "zs.h" 	/* NZS */

/* Make life easier for the initialized arrays here. */
#if NZS < 3
#undef  NZS
#define NZS 3
#endif

/*
 * Some warts needed by z8530tty.c -
 * The default parity REALLY needs to be the same as the PROM uses,
 * or you can not see messages done with printf during boot-up...
 */
int zs_def_cflag = (CREAD | CS8 | HUPCL);

/*
 * The Sun provides a 4.9152 MHz clock to the ZS chips.
 */
#define PCLK	(9600 * 512)	/* PCLK pin input clock rate */

#define	ZS_DELAY()

/* The layout of this is hardware-dependent (padding, order). */
struct zschan {
	volatile uint8_t zc_csr;	/* ctrl,status, and indirect access */
	uint8_t		zc_xxx0;
	volatile uint8_t zc_data;	/* data */
	uint8_t		zc_xxx1;
};
struct zsdevice {
	/* Yes, they are backwards. */
	struct	zschan zs_chan_b;
	struct	zschan zs_chan_a;
};

/* ZS channel used as the console device (if any) */
void *zs_conschan_get, *zs_conschan_put;

/* Saved PROM mappings */
static struct zsdevice *zsaddr[NZS];

static uint8_t zs_init_reg[16] = {
	0,	/* 0: CMD (reset, etc.) */
	0,	/* 1: No interrupts yet. */
	0,	/* 2: IVECT */
	ZSWR3_RX_8 | ZSWR3_RX_ENABLE,
	ZSWR4_CLK_X16 | ZSWR4_ONESB | ZSWR4_EVENP,
	ZSWR5_TX_8 | ZSWR5_TX_ENABLE,
	0,	/* 6: TXSYNC/SYNCLO */
	0,	/* 7: RXSYNC/SYNCHI */
	0,	/* 8: alias for data port */
	ZSWR9_MASTER_IE | ZSWR9_NO_VECTOR,
	0,	/*10: Misc. TX/RX control bits */
	ZSWR11_TXCLK_BAUD | ZSWR11_RXCLK_BAUD,
	((PCLK/32)/9600)-2,	/*12: BAUDLO (default=9600) */
	0,			/*13: BAUDHI (default=9600) */
	ZSWR14_BAUD_ENA | ZSWR14_BAUD_FROM_PCLK,
	ZSWR15_BREAK_IE,
};

/* Console ops */
static int  zscngetc(dev_t);
static void zscnputc(dev_t, int);
static void zscnpollc(dev_t, int);

struct consdev zs_consdev = {
	.cn_getc = zscngetc,
	.cn_putc = zscnputc,
	.cn_pollc = zscnpollc,
};


/****************************************************************
 * Autoconfig
 ****************************************************************/

/* Definition of the driver for autoconfig. */
static int  zs_match_sbus(device_t, cfdata_t, void *);
static void zs_attach_sbus(device_t, device_t, void *);

static int  zs_match_fhc(device_t, cfdata_t, void *);
static void zs_attach_fhc(device_t, device_t, void *);

static void zs_attach(struct zsc_softc *, struct zsdevice *, int);
static int  zs_print(void *, const char *);

CFATTACH_DECL_NEW(zs, sizeof(struct zsc_softc),
    zs_match_sbus, zs_attach_sbus, NULL, NULL);

CFATTACH_DECL_NEW(zs_fhc, sizeof(struct zsc_softc),
    zs_match_fhc, zs_attach_fhc, NULL, NULL);

/* Interrupt handlers. */
int zscheckintr(void *);
static int zshard(void *);
static void zssoft(void *);

static int zs_get_speed(struct zs_chanstate *);

/* Console device support */
static int zs_console_flags(int, int, int);

/* Power management hooks */
int  zs_enable(struct zs_chanstate *);
void zs_disable(struct zs_chanstate *);

/* from dev/ic/z8530tty.c */
struct tty *zstty_get_tty_from_dev(device_t);

/*
 * Is the zs chip present?
 */
static int
zs_match_sbus(device_t parent, cfdata_t cf, void *aux)
{
	struct sbus_attach_args *sa = aux;

	if (strcmp(cf->cf_name, sa->sa_name) != 0)
		return (0);

	return (1);
}

static int
zs_match_fhc(device_t parent, cfdata_t cf, void *aux)
{
	struct fhc_attach_args *fa = aux;

	if (strcmp(cf->cf_name, fa->fa_name) != 0)
		return (0);

	return (1);
}

static void
zs_attach_sbus(device_t parent, device_t self, void *aux)
{
	struct zsc_softc *zsc = device_private(self);
	struct sbus_attach_args *sa = aux;
	bus_space_handle_t bh;
	int zs_unit;

	zsc->zsc_dev = self;
	zs_unit = device_unit(self);

	if (sa->sa_nintr == 0) {
		aprint_error(": no interrupt lines\n");
		return;
	}

	/* Use the mapping setup by the Sun PROM if possible. */
	if (zsaddr[zs_unit] == NULL) {
		/* Only map registers once. */
		if (sa->sa_npromvaddrs) {
			/*
			 * We're converting from a 32-bit pointer to a 64-bit
			 * pointer.  Since the 32-bit entity is negative, but
			 * the kernel is still mapped into the lower 4GB
			 * range, this needs to be zero-extended.
			 *
			 * XXXXX If we map the kernel and devices into the
			 * high 4GB range, this needs to be changed to
			 * sign-extend the address.
			 */
			sparc_promaddr_to_handle(sa->sa_bustag,
				sa->sa_promvaddrs[0], &bh);

		} else {

			if (sbus_bus_map(sa->sa_bustag, sa->sa_slot,
					 sa->sa_offset,
					 sa->sa_size,
					 BUS_SPACE_MAP_LINEAR,
					 &bh) != 0) {
				aprint_error(": cannot map registers\n");
				return;
			}
		}
		zsaddr[zs_unit] = bus_space_vaddr(sa->sa_bustag, bh);
	}
	zsc->zsc_bustag = sa->sa_bustag;
	zsc->zsc_dmatag = sa->sa_dmatag;
	zsc->zsc_promunit = prom_getpropint(sa->sa_node, "slave", -2);
	zsc->zsc_node = sa->sa_node;
	aprint_normal("\n");
	zs_attach(zsc, zsaddr[zs_unit], sa->sa_pri);
}

static void
zs_attach_fhc(device_t parent, device_t self, void *aux)
{
	struct zsc_softc *zsc = device_private(self);
	struct fhc_attach_args *fa = aux;
	bus_space_handle_t bh;
	int zs_unit;

	zsc->zsc_dev = self;
	zs_unit = device_unit(self);

	if (fa->fa_nreg < 1 && fa->fa_npromvaddrs < 1) {
		printf(": no registers\n");
		return;
	}

	if (fa->fa_nintr == 0) {
		aprint_error(": no interrupt lines\n");
		return;
	}

	/* Use the mapping setup by the Sun PROM if possible. */
	if (zsaddr[zs_unit] == NULL) {
		/* Only map registers once. */
		if (fa->fa_npromvaddrs) {
			/*
			 * We're converting from a 32-bit pointer to a 64-bit
			 * pointer.  Since the 32-bit entity is negative, but
			 * the kernel is still mapped into the lower 4GB
			 * range, this needs to be zero-extended.
			 *
			 * XXXXX If we map the kernel and devices into the
			 * high 4GB range, this needs to be changed to
			 * sign-extend the address.
			 */
			sparc_promaddr_to_handle(fa->fa_bustag,
				fa->fa_promvaddrs[0], &bh);

		} else {

			if (fhc_bus_map(fa->fa_bustag,
					fa->fa_reg[0].fbr_slot,
					fa->fa_reg[0].fbr_offset,
					fa->fa_reg[0].fbr_size,
					BUS_SPACE_MAP_LINEAR,
					&bh) != 0) {
				aprint_error(": cannot map registers\n");
				return;
			}
		}
		zsaddr[zs_unit] = bus_space_vaddr(fa->fa_bustag, bh);
	}
	zsc->zsc_bustag = fa->fa_bustag;
	zsc->zsc_dmatag = NULL;
	zsc->zsc_promunit = prom_getpropint(fa->fa_node, "slave", -2);
	zsc->zsc_node = fa->fa_node;
	aprint_normal("\n");
	zs_attach(zsc, zsaddr[zs_unit], fa->fa_intr[0]);
}

/*
 * Attach a found zs.
 *
 * USE ROM PROPERTIES port-a-ignore-cd AND port-b-ignore-cd FOR
 * SOFT CARRIER, AND keyboard PROPERTY FOR KEYBOARD/MOUSE?
 */
static void
zs_attach(struct zsc_softc *zsc, struct zsdevice *zsd, int pri)
{
	struct zsc_attach_args zsc_args;
	struct zs_chanstate *cs;
	int channel;

	if (zsd == NULL) {
		aprint_error(": configuration incomplete\n");
		return;
	}

	/*
	 * Initialize software state for each channel.
	 */
	for (channel = 0; channel < 2; channel++) {
		struct zschan *zc;
		device_t child;

		zsc_args.channel = channel;
		cs = &zsc->zsc_cs_store[channel];
		zsc->zsc_cs[channel] = cs;

		zs_lock_init(cs);
		cs->cs_channel = channel;
		cs->cs_private = NULL;
		cs->cs_ops = &zsops_null;
		cs->cs_brg_clk = PCLK / 16;

		zc = (channel == 0) ? &zsd->zs_chan_a : &zsd->zs_chan_b;

		zsc_args.consdev = NULL;
		zsc_args.hwflags = zs_console_flags(zsc->zsc_promunit,
						    zsc->zsc_node,
						    channel);

		if (zsc_args.hwflags & ZS_HWFLAG_CONSOLE) {
			zsc_args.hwflags |= ZS_HWFLAG_USE_CONSDEV;
			zsc_args.consdev = &zs_consdev;
		}

		if ((zsc_args.hwflags & ZS_HWFLAG_CONSOLE_INPUT) != 0) {
			zs_conschan_get = zc;
		}
		if ((zsc_args.hwflags & ZS_HWFLAG_CONSOLE_OUTPUT) != 0) {
			zs_conschan_put = zc;
		}

		/* Children need to set cn_dev, etc */
		cs->cs_reg_csr  = &zc->zc_csr;
		cs->cs_reg_data = &zc->zc_data;

		memcpy(cs->cs_creg, zs_init_reg, 16);
		memcpy(cs->cs_preg, zs_init_reg, 16);

		/* XXX: Consult PROM properties for this?! */
		cs->cs_defspeed = zs_get_speed(cs);
		cs->cs_defcflag = zs_def_cflag;

		/* Make these correspond to cs_defcflag (-crtscts) */
		cs->cs_rr0_dcd = ZSRR0_DCD;
		cs->cs_rr0_cts = 0;
		cs->cs_wr5_dtr = ZSWR5_DTR | ZSWR5_RTS;
		cs->cs_wr5_rts = 0;

		/*
		 * Clear the master interrupt enable.
		 * The INTENA is common to both channels,
		 * so just do it on the A channel.
		 */
		if (channel == 0) {
			zs_write_reg(cs, 9, 0);
		}

		/*
		 * Look for a child driver for this channel.
		 * The child attach will setup the hardware.
		 */
		child = config_found(zsc->zsc_dev, (void *)&zsc_args, 
		    zs_print);
		if (child == NULL) {
			/* No sub-driver.  Just reset it. */
			uint8_t reset = (channel == 0) ?
				ZSWR9_A_RESET : ZSWR9_B_RESET;
			zs_lock_chan(cs);
			zs_write_reg(cs,  9, reset);
			zs_unlock_chan(cs);
		} 
#if (NKBD > 0) || (NMS > 0)
		/* 
		 * If this was a zstty it has a keyboard
		 * property on it we need to attach the
		 * sunkbd and sunms line disciplines.
		 */
		if (child 
		    && (device_is_a(child, "zstty"))
		    && (prom_getproplen(zsc->zsc_node, "keyboard") == 0)) {
			struct kbd_ms_tty_attach_args kma;
			struct tty *tp;

			kma.kmta_tp = tp = zstty_get_tty_from_dev(child);
			kma.kmta_dev = tp->t_dev;
			kma.kmta_consdev = zsc_args.consdev;
			
			/* Attach 'em if we got 'em. */
#if (NKBD > 0)
			if (channel == 0) {
				kma.kmta_name = "keyboard";
				config_found(child, (void *)&kma, NULL);
			}
#endif
#if (NMS > 0)
			if (channel == 1) {
				kma.kmta_name = "mouse";
				config_found(child, (void *)&kma, NULL);
			}
#endif
		}
#endif
	}

	/*
	 * Now safe to install interrupt handlers.  Note the arguments
	 * to the interrupt handlers aren't used.  Note, we only do this
	 * once since both SCCs interrupt at the same level and vector.
	 */
	bus_intr_establish(zsc->zsc_bustag, pri, IPL_SERIAL, zshard, zsc);
	if (!(zsc->zsc_softintr = softint_establish(SOFTINT_SERIAL, zssoft, zsc)))
		panic("zsattach: could not establish soft interrupt");

	evcnt_attach_dynamic(&zsc->zsc_intrcnt, EVCNT_TYPE_INTR, NULL,
	    device_xname(zsc->zsc_dev), "intr");


	/*
	 * Set the master interrupt enable and interrupt vector.
	 * (common to both channels, do it on A)
	 */
	cs = zsc->zsc_cs[0];
	zs_lock_chan(cs);
	/* interrupt vector */
	zs_write_reg(cs, 2, zs_init_reg[2]);
	/* master interrupt control (enable) */
	zs_write_reg(cs, 9, zs_init_reg[9]);
	zs_unlock_chan(cs);
}

static int
zs_print(void *aux, const char *name)
{
	struct zsc_attach_args *args = aux;

	if (name != NULL)
		aprint_normal("%s: ", name);

	if (args->channel != -1)
		aprint_normal(" channel %d", args->channel);

	return (UNCONF);
}

static int
zshard(void *arg)
{
	struct zsc_softc *zsc = arg;
	int rr3, rval;

	rval = 0;
	while ((rr3 = zsc_intr_hard(zsc))) {
		/* Count up the interrupts. */
		rval |= rr3;
		zsc->zsc_intrcnt.ev_count++;
	}
	if (((zsc->zsc_cs[0] && zsc->zsc_cs[0]->cs_softreq) ||
	     (zsc->zsc_cs[1] && zsc->zsc_cs[1]->cs_softreq)) &&
	    zsc->zsc_softintr) {
		softint_schedule(zsc->zsc_softintr);
	}
	return (rval);
}

int
zscheckintr(void *arg)
{
	struct zsc_softc *zsc;
	int unit, rval;

	rval = 0;
	for (unit = 0; unit < zs_cd.cd_ndevs; unit++) {

		zsc = device_lookup_private(&zs_cd, unit);
		if (zsc == NULL)
			continue;
		rval = (zshard((void *)zsc) || rval);
	}
	return (rval);
}


/*
 * We need this only for TTY_DEBUG purposes.
 */
static void
zssoft(void *arg)
{
	struct zsc_softc *zsc = arg;

#if 0 /* not yet */
	/* Make sure we call the tty layer with tty_lock held. */
	mutex_spin_enter(&tty_lock);
#endif
	(void)zsc_intr_soft(zsc);
#ifdef TTY_DEBUG
	{
		struct zstty_softc *zst0 = zsc->zsc_cs[0]->cs_private;
		struct zstty_softc *zst1 = zsc->zsc_cs[1]->cs_private;
		if (zst0->zst_overflows || zst1->zst_overflows ) {
			struct trapframe *frame = (struct trapframe *)arg;
			
			printf("zs silo overflow from %p\n",
			       (long)frame->tf_pc);
		}
	}
#endif
#if 0 /* not yet */
	mutex_spin_exit(&tty_lock);
#endif
}


/*
 * Compute the current baud rate given a ZS channel.
 */
static int
zs_get_speed(struct zs_chanstate *cs)
{
	int tconst;

	tconst = zs_read_reg(cs, 12);
	tconst |= zs_read_reg(cs, 13) << 8;
	return (TCONST_TO_BPS(cs->cs_brg_clk, tconst));
}

/*
 * MD functions for setting the baud rate and control modes.
 */
int
zs_set_speed(struct zs_chanstate *cs, int bps /* bits per second */)
{
	int tconst, real_bps;

	if (bps == 0)
		return (0);

#ifdef	DIAGNOSTIC
	if (cs->cs_brg_clk == 0)
		panic("zs_set_speed");
#endif

	tconst = BPS_TO_TCONST(cs->cs_brg_clk, bps);
	if (tconst < 0)
		return (EINVAL);

	/* Convert back to make sure we can do it. */
	real_bps = TCONST_TO_BPS(cs->cs_brg_clk, tconst);

	/* XXX - Allow some tolerance here? */
	if (real_bps != bps)
		return (EINVAL);

	cs->cs_preg[12] = tconst;
	cs->cs_preg[13] = tconst >> 8;

	/* Caller will stuff the pending registers. */
	return (0);
}

int
zs_set_modes(struct zs_chanstate *cs, int cflag)
{

	/*
	 * Output hardware flow control on the chip is horrendous:
	 * if carrier detect drops, the receiver is disabled, and if
	 * CTS drops, the transmitter is stoped IN MID CHARACTER!
	 * Therefore, NEVER set the HFC bit, and instead use the
	 * status interrupt to detect CTS changes.
	 */
	zs_lock_chan(cs);
	cs->cs_rr0_pps = 0;
	if ((cflag & (CLOCAL | MDMBUF)) != 0) {
		cs->cs_rr0_dcd = 0;
		if ((cflag & MDMBUF) == 0)
			cs->cs_rr0_pps = ZSRR0_DCD;
	} else
		cs->cs_rr0_dcd = ZSRR0_DCD;
	if ((cflag & CRTSCTS) != 0) {
		cs->cs_wr5_dtr = ZSWR5_DTR;
		cs->cs_wr5_rts = ZSWR5_RTS;
		cs->cs_rr0_cts = ZSRR0_CTS;
	} else if ((cflag & CDTRCTS) != 0) {
		cs->cs_wr5_dtr = 0;
		cs->cs_wr5_rts = ZSWR5_DTR;
		cs->cs_rr0_cts = ZSRR0_CTS;
	} else if ((cflag & MDMBUF) != 0) {
		cs->cs_wr5_dtr = 0;
		cs->cs_wr5_rts = ZSWR5_DTR;
		cs->cs_rr0_cts = ZSRR0_DCD;
	} else {
		cs->cs_wr5_dtr = ZSWR5_DTR | ZSWR5_RTS;
		cs->cs_wr5_rts = 0;
		cs->cs_rr0_cts = 0;
	}
	zs_unlock_chan(cs);

	/* Caller will stuff the pending registers. */
	return (0);
}


/*
 * Read or write the chip with suitable delays.
 */

u_char
zs_read_reg(struct zs_chanstate *cs, u_char reg)
{
	u_char val;

	*cs->cs_reg_csr = reg;
	ZS_DELAY();
	val = *cs->cs_reg_csr;
	ZS_DELAY();
	return (val);
}

void
zs_write_reg(struct zs_chanstate *cs, u_char reg, u_char val)
{
	*cs->cs_reg_csr = reg;
	ZS_DELAY();
	*cs->cs_reg_csr = val;
	ZS_DELAY();
}

u_char
zs_read_csr(struct zs_chanstate *cs)
{
	u_char val;

	val = *cs->cs_reg_csr;
	ZS_DELAY();
	return (val);
}

void
zs_write_csr(struct zs_chanstate *cs, u_char val)
{
	*cs->cs_reg_csr = val;
	ZS_DELAY();
}

u_char
zs_read_data(struct zs_chanstate *cs)
{
	u_char val;

	val = *cs->cs_reg_data;
	ZS_DELAY();
	return (val);
}

void
zs_write_data(struct zs_chanstate *cs, u_char val)
{
	*cs->cs_reg_data = val;
	ZS_DELAY();
}

/****************************************************************
 * Console support functions (Sun specific!)
 * Note: this code is allowed to know about the layout of
 * the chip registers, and uses that to keep things simple.
 * XXX - I think I like the mvme167 code better. -gwr
 ****************************************************************/

extern void Debugger(void);

/*
 * Handle user request to enter kernel debugger.
 */
void
zs_abort(struct zs_chanstate *cs)
{
	volatile struct zschan *zc = zs_conschan_get;
	int rr0;

	/* Wait for end of break to avoid PROM abort. */
	/* XXX - Limit the wait? */
	do {
		rr0 = zc->zc_csr;
		ZS_DELAY();
	} while (rr0 & ZSRR0_BREAK);

#if defined(KGDB)
	zskgdb(cs);
#elif defined(DDB)
	{
		extern int db_active;
		
		if (!db_active)
			Debugger();
		else
			/* Debugger is probably hozed */
			callrom();
	}
#else
	printf("stopping on keyboard abort\n");
	callrom();
#endif
}


/*
 * Polled input char.
 */
int
zs_getc(void *arg)
{
	volatile struct zschan *zc = arg;
	int s, c, rr0;

	s = splhigh();
	/* Wait for a character to arrive. */
	do {
		rr0 = zc->zc_csr;
		ZS_DELAY();
	} while ((rr0 & ZSRR0_RX_READY) == 0);

	c = zc->zc_data;
	ZS_DELAY();
	splx(s);

	/*
	 * This is used by the kd driver to read scan codes,
	 * so don't translate '\r' ==> '\n' here...
	 */
	return (c);
}

/*
 * Polled output char.
 */
void
zs_putc(void *arg, int c)
{
	volatile struct zschan *zc = arg;
	int s, rr0;

	s = splhigh();

	/* Wait for transmitter to become ready. */
	do {
		rr0 = zc->zc_csr;
		ZS_DELAY();
	} while ((rr0 & ZSRR0_TX_READY) == 0);

	/*
	 * Send the next character.
	 * Now you'd think that this could be followed by a ZS_DELAY()
	 * just like all the other chip accesses, but it turns out that
	 * the `transmit-ready' interrupt isn't de-asserted until
	 * some period of time after the register write completes
	 * (more than a couple instructions).  So to avoid stray
	 * interrupts we put in the 2us delay regardless of CPU model.
	 */
	zc->zc_data = c;
	delay(2);

	splx(s);
}

/*****************************************************************/




/*
 * Polled console input putchar.
 */
static int
zscngetc(dev_t dev)
{
	return (zs_getc(zs_conschan_get));
}

/*
 * Polled console output putchar.
 */
static void
zscnputc(dev_t dev, int c)
{
	zs_putc(zs_conschan_put, c);
}

int swallow_zsintrs;

static void
zscnpollc(dev_t dev, int on)
{
	/* 
	 * Need to tell zs driver to acknowledge all interrupts or we get
	 * annoying spurious interrupt messages.  This is because mucking
	 * with spl() levels during polling does not prevent interrupts from
	 * being generated.
	 */

	if (on) swallow_zsintrs++;
	else swallow_zsintrs--;
}

int
zs_console_flags(int promunit, int node, int channel)
{
	int cookie, flags = 0;
	char buf[255];

	/*
	 * We'll just do the OBP grovelling down here since that's
	 * the only type of firmware we support.
	 */

	/* Default to channel 0 if there are no explicit prom args */
	cookie = 0;
	if (node == prom_instance_to_package(prom_stdin())) {
		if (prom_getoption("input-device", buf, sizeof buf) == 0 &&
		    strcmp("ttyb", buf) == 0)
			cookie = 1;

		if (channel == cookie)
			flags |= ZS_HWFLAG_CONSOLE_INPUT;
	}

	if (node == prom_instance_to_package(prom_stdout())) { 
		if (prom_getoption("output-device", buf, sizeof buf) == 0 &&
		    strcmp("ttyb", buf) == 0)
			cookie = 1;

		if (channel == cookie)
			flags |= ZS_HWFLAG_CONSOLE_OUTPUT;
	}

	return (flags);
}