summaryrefslogtreecommitdiffstats
path: root/drivers/tty/serial/sn_console.c
blob: fe9170731c167a4f09ee0f60047de1ca46f05834 (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
/*
 * C-Brick Serial Port (and console) driver for SGI Altix machines.
 *
 * This driver is NOT suitable for talking to the l1-controller for
 * anything other than 'console activities' --- please use the l1
 * driver for that.
 *
 *
 * Copyright (c) 2004-2006 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * Contact information:  Silicon Graphics, Inc., 1500 Crittenden Lane,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/NoticeExplan
 */

#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/sysrq.h>
#include <linux/circ_buf.h>
#include <linux/serial_reg.h>
#include <linux/delay.h> /* for mdelay */
#include <linux/miscdevice.h>
#include <linux/serial_core.h>

#include <asm/io.h>
#include <asm/sn/simulator.h>
#include <asm/sn/sn_sal.h>

/* number of characters we can transmit to the SAL console at a time */
#define SN_SAL_MAX_CHARS 120

/* 64K, when we're asynch, it must be at least printk's LOG_BUF_LEN to
 * avoid losing chars, (always has to be a power of 2) */
#define SN_SAL_BUFFER_SIZE (64 * (1 << 10))

#define SN_SAL_UART_FIFO_DEPTH 16
#define SN_SAL_UART_FIFO_SPEED_CPS (9600/10)

/* sn_transmit_chars() calling args */
#define TRANSMIT_BUFFERED	0
#define TRANSMIT_RAW		1

/* To use dynamic numbers only and not use the assigned major and minor,
 * define the following.. */
				  /* #define USE_DYNAMIC_MINOR 1 *//* use dynamic minor number */
#define USE_DYNAMIC_MINOR 0	/* Don't rely on misc_register dynamic minor */

/* Device name we're using */
#define DEVICE_NAME "ttySG"
#define DEVICE_NAME_DYNAMIC "ttySG0"	/* need full name for misc_register */
/* The major/minor we are using, ignored for USE_DYNAMIC_MINOR */
#define DEVICE_MAJOR 204
#define DEVICE_MINOR 40

#ifdef CONFIG_MAGIC_SYSRQ
static char sysrq_serial_str[] = "\eSYS";
static char *sysrq_serial_ptr = sysrq_serial_str;
static unsigned long sysrq_requested;
#endif /* CONFIG_MAGIC_SYSRQ */

/*
 * Port definition - this kinda drives it all
 */
struct sn_cons_port {
	struct timer_list sc_timer;
	struct uart_port sc_port;
	struct sn_sal_ops {
		int (*sal_puts_raw) (const char *s, int len);
		int (*sal_puts) (const char *s, int len);
		int (*sal_getc) (void);
		int (*sal_input_pending) (void);
		void (*sal_wakeup_transmit) (struct sn_cons_port *, int);
	} *sc_ops;
	unsigned long sc_interrupt_timeout;
	int sc_is_asynch;
};

static struct sn_cons_port sal_console_port;
static int sn_process_input;

/* Only used if USE_DYNAMIC_MINOR is set to 1 */
static struct miscdevice misc;	/* used with misc_register for dynamic */

extern void early_sn_setup(void);

#undef DEBUG
#ifdef DEBUG
static int sn_debug_printf(const char *fmt, ...);
#define DPRINTF(x...) sn_debug_printf(x)
#else
#define DPRINTF(x...) do { } while (0)
#endif

/* Prototypes */
static int snt_hw_puts_raw(const char *, int);
static int snt_hw_puts_buffered(const char *, int);
static int snt_poll_getc(void);
static int snt_poll_input_pending(void);
static int snt_intr_getc(void);
static int snt_intr_input_pending(void);
static void sn_transmit_chars(struct sn_cons_port *, int);

/* A table for polling:
 */
static struct sn_sal_ops poll_ops = {
	.sal_puts_raw = snt_hw_puts_raw,
	.sal_puts = snt_hw_puts_raw,
	.sal_getc = snt_poll_getc,
	.sal_input_pending = snt_poll_input_pending
};

/* A table for interrupts enabled */
static struct sn_sal_ops intr_ops = {
	.sal_puts_raw = snt_hw_puts_raw,
	.sal_puts = snt_hw_puts_buffered,
	.sal_getc = snt_intr_getc,
	.sal_input_pending = snt_intr_input_pending,
	.sal_wakeup_transmit = sn_transmit_chars
};

/* the console does output in two distinctly different ways:
 * synchronous (raw) and asynchronous (buffered).  initially, early_printk
 * does synchronous output.  any data written goes directly to the SAL
 * to be output (incidentally, it is internally buffered by the SAL)
 * after interrupts and timers are initialized and available for use,
 * the console init code switches to asynchronous output.  this is
 * also the earliest opportunity to begin polling for console input.
 * after console initialization, console output and tty (serial port)
 * output is buffered and sent to the SAL asynchronously (either by
 * timer callback or by UART interrupt) */

/* routines for running the console in polling mode */

/**
 * snt_poll_getc - Get a character from the console in polling mode
 *
 */
static int snt_poll_getc(void)
{
	int ch;

	ia64_sn_console_getc(&ch);
	return ch;
}

/**
 * snt_poll_input_pending - Check if any input is waiting - polling mode.
 *
 */
static int snt_poll_input_pending(void)
{
	int status, input;

	status = ia64_sn_console_check(&input);
	return !status && input;
}

/* routines for an interrupt driven console (normal) */

/**
 * snt_intr_getc - Get a character from the console, interrupt mode
 *
 */
static int snt_intr_getc(void)
{
	return ia64_sn_console_readc();
}

/**
 * snt_intr_input_pending - Check if input is pending, interrupt mode
 *
 */
static int snt_intr_input_pending(void)
{
	return ia64_sn_console_intr_status() & SAL_CONSOLE_INTR_RECV;
}

/* these functions are polled and interrupt */

/**
 * snt_hw_puts_raw - Send raw string to the console, polled or interrupt mode
 * @s: String
 * @len: Length
 *
 */
static int snt_hw_puts_raw(const char *s, int len)
{
	/* this will call the PROM and not return until this is done */
	return ia64_sn_console_putb(s, len);
}

/**
 * snt_hw_puts_buffered - Send string to console, polled or interrupt mode
 * @s: String
 * @len: Length
 *
 */
static int snt_hw_puts_buffered(const char *s, int len)
{
	/* queue data to the PROM */
	return ia64_sn_console_xmit_chars((char *)s, len);
}

/* uart interface structs
 * These functions are associated with the uart_port that the serial core
 * infrastructure calls.
 *
 * Note: Due to how the console works, many routines are no-ops.
 */

/**
 * snp_type - What type of console are we?
 * @port: Port to operate with (we ignore since we only have one port)
 *
 */
static const char *snp_type(struct uart_port *port)
{
	return ("SGI SN L1");
}

/**
 * snp_tx_empty - Is the transmitter empty?  We pretend we're always empty
 * @port: Port to operate on (we ignore since we only have one port)
 *
 */
static unsigned int snp_tx_empty(struct uart_port *port)
{
	return 1;
}

/**
 * snp_stop_tx - stop the transmitter - no-op for us
 * @port: Port to operat eon - we ignore - no-op function
 *
 */
static void snp_stop_tx(struct uart_port *port)
{
}

/**
 * snp_release_port - Free i/o and resources for port - no-op for us
 * @port: Port to operate on - we ignore - no-op function
 *
 */
static void snp_release_port(struct uart_port *port)
{
}

/**
 * snp_shutdown - shut down the port - free irq and disable - no-op for us
 * @port: Port to shut down - we ignore
 *
 */
static void snp_shutdown(struct uart_port *port)
{
}

/**
 * snp_set_mctrl - set control lines (dtr, rts, etc) - no-op for our console
 * @port: Port to operate on - we ignore
 * @mctrl: Lines to set/unset - we ignore
 *
 */
static void snp_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}

/**
 * snp_get_mctrl - get contorl line info, we just return a static value
 * @port: port to operate on - we only have one port so we ignore this
 *
 */
static unsigned int snp_get_mctrl(struct uart_port *port)
{
	return TIOCM_CAR | TIOCM_RNG | TIOCM_DSR | TIOCM_CTS;
}

/**
 * snp_stop_rx - Stop the receiver - we ignor ethis
 * @port: Port to operate on - we ignore
 *
 */
static void snp_stop_rx(struct uart_port *port)
{
}

/**
 * snp_start_tx - Start transmitter
 * @port: Port to operate on
 *
 */
static void snp_start_tx(struct uart_port *port)
{
	if (sal_console_port.sc_ops->sal_wakeup_transmit)
		sal_console_port.sc_ops->sal_wakeup_transmit(&sal_console_port,
							     TRANSMIT_BUFFERED);

}

/**
 * snp_break_ctl - handle breaks - ignored by us
 * @port: Port to operate on
 * @break_state: Break state
 *
 */
static void snp_break_ctl(struct uart_port *port, int break_state)
{
}

/**
 * snp_startup - Start up the serial port - always return 0 (We're always on)
 * @port: Port to operate on
 *
 */
static int snp_startup(struct uart_port *port)
{
	return 0;
}

/**
 * snp_set_termios - set termios stuff - we ignore these
 * @port: port to operate on
 * @termios: New settings
 * @termios: Old
 *
 */
static void
snp_set_termios(struct uart_port *port, struct ktermios *termios,
		struct ktermios *old)
{
}

/**
 * snp_request_port - allocate resources for port - ignored by us
 * @port: port to operate on
 *
 */
static int snp_request_port(struct uart_port *port)
{
	return 0;
}

/**
 * snp_config_port - allocate resources, set up - we ignore,  we're always on
 * @port: Port to operate on
 * @flags: flags used for port setup
 *
 */
static void snp_config_port(struct uart_port *port, int flags)
{
}

/* Associate the uart functions above - given to serial core */

static const struct uart_ops sn_console_ops = {
	.tx_empty = snp_tx_empty,
	.set_mctrl = snp_set_mctrl,
	.get_mctrl = snp_get_mctrl,
	.stop_tx = snp_stop_tx,
	.start_tx = snp_start_tx,
	.stop_rx = snp_stop_rx,
	.break_ctl = snp_break_ctl,
	.startup = snp_startup,
	.shutdown = snp_shutdown,
	.set_termios = snp_set_termios,
	.pm = NULL,
	.type = snp_type,
	.release_port = snp_release_port,
	.request_port = snp_request_port,
	.config_port = snp_config_port,
	.verify_port = NULL,
};

/* End of uart struct functions and defines */

#ifdef DEBUG

/**
 * sn_debug_printf - close to hardware debugging printf
 * @fmt: printf format
 *
 * This is as "close to the metal" as we can get, used when the driver
 * itself may be broken.
 *
 */
static int sn_debug_printf(const char *fmt, ...)
{
	static char printk_buf[1024];
	int printed_len;
	va_list args;

	va_start(args, fmt);
	printed_len = vsnprintf(printk_buf, sizeof(printk_buf), fmt, args);

	if (!sal_console_port.sc_ops) {
		sal_console_port.sc_ops = &poll_ops;
		early_sn_setup();
	}
	sal_console_port.sc_ops->sal_puts_raw(printk_buf, printed_len);

	va_end(args);
	return printed_len;
}
#endif				/* DEBUG */

/*
 * Interrupt handling routines.
 */

/**
 * sn_receive_chars - Grab characters, pass them to tty layer
 * @port: Port to operate on
 * @flags: irq flags
 *
 * Note: If we're not registered with the serial core infrastructure yet,
 * we don't try to send characters to it...
 *
 */
static void
sn_receive_chars(struct sn_cons_port *port, unsigned long flags)
{
	struct tty_port *tport = NULL;
	int ch;

	if (!port) {
		printk(KERN_ERR "sn_receive_chars - port NULL so can't receive\n");
		return;
	}

	if (!port->sc_ops) {
		printk(KERN_ERR "sn_receive_chars - port->sc_ops  NULL so can't receive\n");
		return;
	}

	if (port->sc_port.state) {
		/* The serial_core stuffs are initialized, use them */
		tport = &port->sc_port.state->port;
	}

	while (port->sc_ops->sal_input_pending()) {
		ch = port->sc_ops->sal_getc();
		if (ch < 0) {
			printk(KERN_ERR "sn_console: An error occurred while "
			       "obtaining data from the console (0x%0x)\n", ch);
			break;
		}
#ifdef CONFIG_MAGIC_SYSRQ
                if (sysrq_requested) {
                        unsigned long sysrq_timeout = sysrq_requested + HZ*5;

                        sysrq_requested = 0;
                        if (ch && time_before(jiffies, sysrq_timeout)) {
                                spin_unlock_irqrestore(&port->sc_port.lock, flags);
                                handle_sysrq(ch);
                                spin_lock_irqsave(&port->sc_port.lock, flags);
                                /* ignore actual sysrq command char */
                                continue;
                        }
                }
                if (ch == *sysrq_serial_ptr) {
                        if (!(*++sysrq_serial_ptr)) {
                                sysrq_requested = jiffies;
                                sysrq_serial_ptr = sysrq_serial_str;
                        }
			/*
			 * ignore the whole sysrq string except for the
			 * leading escape
			 */
			if (ch != '\e')
				continue;
                }
                else
			sysrq_serial_ptr = sysrq_serial_str;
#endif /* CONFIG_MAGIC_SYSRQ */

		/* record the character to pass up to the tty layer */
		if (tport) {
			if (tty_insert_flip_char(tport, ch, TTY_NORMAL) == 0)
				break;
		}
		port->sc_port.icount.rx++;
	}

	if (tport)
		tty_flip_buffer_push(tport);
}

/**
 * sn_transmit_chars - grab characters from serial core, send off
 * @port: Port to operate on
 * @raw: Transmit raw or buffered
 *
 * Note: If we're early, before we're registered with serial core, the
 * writes are going through sn_sal_console_write because that's how
 * register_console has been set up.  We currently could have asynch
 * polls calling this function due to sn_sal_switch_to_asynch but we can
 * ignore them until we register with the serial core stuffs.
 *
 */
static void sn_transmit_chars(struct sn_cons_port *port, int raw)
{
	int xmit_count, tail, head, loops, ii;
	int result;
	char *start;
	struct circ_buf *xmit;

	if (!port)
		return;

	BUG_ON(!port->sc_is_asynch);

	if (port->sc_port.state) {
		/* We're initialized, using serial core infrastructure */
		xmit = &port->sc_port.state->xmit;
	} else {
		/* Probably sn_sal_switch_to_asynch has been run but serial core isn't
		 * initialized yet.  Just return.  Writes are going through
		 * sn_sal_console_write (due to register_console) at this time.
		 */
		return;
	}

	if (uart_circ_empty(xmit) || uart_tx_stopped(&port->sc_port)) {
		/* Nothing to do. */
		ia64_sn_console_intr_disable(SAL_CONSOLE_INTR_XMIT);
		return;
	}

	head = xmit->head;
	tail = xmit->tail;
	start = &xmit->buf[tail];

	/* twice around gets the tail to the end of the buffer and
	 * then to the head, if needed */
	loops = (head < tail) ? 2 : 1;

	for (ii = 0; ii < loops; ii++) {
		xmit_count = (head < tail) ?
		    (UART_XMIT_SIZE - tail) : (head - tail);

		if (xmit_count > 0) {
			if (raw == TRANSMIT_RAW)
				result =
				    port->sc_ops->sal_puts_raw(start,
							       xmit_count);
			else
				result =
				    port->sc_ops->sal_puts(start, xmit_count);
#ifdef DEBUG
			if (!result)
				DPRINTF("`");
#endif
			if (result > 0) {
				xmit_count -= result;
				port->sc_port.icount.tx += result;
				tail += result;
				tail &= UART_XMIT_SIZE - 1;
				xmit->tail = tail;
				start = &xmit->buf[tail];
			}
		}
	}

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

	if (uart_circ_empty(xmit))
		snp_stop_tx(&port->sc_port);	/* no-op for us */
}

/**
 * sn_sal_interrupt - Handle console interrupts
 * @irq: irq #, useful for debug statements
 * @dev_id: our pointer to our port (sn_cons_port which contains the uart port)
 *
 */
static irqreturn_t sn_sal_interrupt(int irq, void *dev_id)
{
	struct sn_cons_port *port = (struct sn_cons_port *)dev_id;
	unsigned long flags;
	int status = ia64_sn_console_intr_status();

	if (!port)
		return IRQ_NONE;

	spin_lock_irqsave(&port->sc_port.lock, flags);
	if (status & SAL_CONSOLE_INTR_RECV) {
		sn_receive_chars(port, flags);
	}
	if (status & SAL_CONSOLE_INTR_XMIT) {
		sn_transmit_chars(port, TRANSMIT_BUFFERED);
	}
	spin_unlock_irqrestore(&port->sc_port.lock, flags);
	return IRQ_HANDLED;
}

/**
 * sn_sal_timer_poll - this function handles polled console mode
 * @data: A pointer to our sn_cons_port (which contains the uart port)
 *
 * data is the pointer that init_timer will store for us.  This function is
 * associated with init_timer to see if there is any console traffic.
 * Obviously not used in interrupt mode
 *
 */
static void sn_sal_timer_poll(struct timer_list *t)
{
	struct sn_cons_port *port = from_timer(port, t, sc_timer);
	unsigned long flags;

	if (!port)
		return;

	if (!port->sc_port.irq) {
		spin_lock_irqsave(&port->sc_port.lock, flags);
		if (sn_process_input)
			sn_receive_chars(port, flags);
		sn_transmit_chars(port, TRANSMIT_RAW);
		spin_unlock_irqrestore(&port->sc_port.lock, flags);
		mod_timer(&port->sc_timer,
			  jiffies + port->sc_interrupt_timeout);
	}
}

/*
 * Boot-time initialization code
 */

/**
 * sn_sal_switch_to_asynch - Switch to async mode (as opposed to synch)
 * @port: Our sn_cons_port (which contains the uart port)
 *
 * So this is used by sn_sal_serial_console_init (early on, before we're
 * registered with serial core).  It's also used by sn_sal_init
 * right after we've registered with serial core.  The later only happens
 * if we didn't already come through here via sn_sal_serial_console_init.
 *
 */
static void __init sn_sal_switch_to_asynch(struct sn_cons_port *port)
{
	unsigned long flags;

	if (!port)
		return;

	DPRINTF("sn_console: about to switch to asynchronous console\n");

	/* without early_printk, we may be invoked late enough to race
	 * with other cpus doing console IO at this point, however
	 * console interrupts will never be enabled */
	spin_lock_irqsave(&port->sc_port.lock, flags);

	/* early_printk invocation may have done this for us */
	if (!port->sc_ops)
		port->sc_ops = &poll_ops;

	/* we can't turn on the console interrupt (as request_irq
	 * calls kmalloc, which isn't set up yet), so we rely on a
	 * timer to poll for input and push data from the console
	 * buffer.
	 */
	timer_setup(&port->sc_timer, sn_sal_timer_poll, 0);

	if (IS_RUNNING_ON_SIMULATOR())
		port->sc_interrupt_timeout = 6;
	else {
		/* 960cps / 16 char FIFO = 60HZ
		 * HZ / (SN_SAL_FIFO_SPEED_CPS / SN_SAL_FIFO_DEPTH) */
		port->sc_interrupt_timeout =
		    HZ * SN_SAL_UART_FIFO_DEPTH / SN_SAL_UART_FIFO_SPEED_CPS;
	}
	mod_timer(&port->sc_timer, jiffies + port->sc_interrupt_timeout);

	port->sc_is_asynch = 1;
	spin_unlock_irqrestore(&port->sc_port.lock, flags);
}

/**
 * sn_sal_switch_to_interrupts - Switch to interrupt driven mode
 * @port: Our sn_cons_port (which contains the uart port)
 *
 * In sn_sal_init, after we're registered with serial core and
 * the port is added, this function is called to switch us to interrupt
 * mode.  We were previously in asynch/polling mode (using init_timer).
 *
 * We attempt to switch to interrupt mode here by calling
 * request_irq.  If that works out, we enable receive interrupts.
 */
static void __init sn_sal_switch_to_interrupts(struct sn_cons_port *port)
{
	unsigned long flags;

	if (port) {
		DPRINTF("sn_console: switching to interrupt driven console\n");

		if (request_irq(SGI_UART_VECTOR, sn_sal_interrupt,
				IRQF_SHARED,
				"SAL console driver", port) >= 0) {
			spin_lock_irqsave(&port->sc_port.lock, flags);
			port->sc_port.irq = SGI_UART_VECTOR;
			port->sc_ops = &intr_ops;
			irq_set_handler(port->sc_port.irq, handle_level_irq);

			/* turn on receive interrupts */
			ia64_sn_console_intr_enable(SAL_CONSOLE_INTR_RECV);
			spin_unlock_irqrestore(&port->sc_port.lock, flags);
		}
		else {
			printk(KERN_INFO
			    "sn_console: console proceeding in polled mode\n");
		}
	}
}

/*
 * Kernel console definitions
 */

static void sn_sal_console_write(struct console *, const char *, unsigned);
static int sn_sal_console_setup(struct console *, char *);
static struct uart_driver sal_console_uart;
extern struct tty_driver *uart_console_device(struct console *, int *);

static struct console sal_console = {
	.name = DEVICE_NAME,
	.write = sn_sal_console_write,
	.device = uart_console_device,
	.setup = sn_sal_console_setup,
	.index = -1,		/* unspecified */
	.data = &sal_console_uart,
};

#define SAL_CONSOLE	&sal_console

static struct uart_driver sal_console_uart = {
	.owner = THIS_MODULE,
	.driver_name = "sn_console",
	.dev_name = DEVICE_NAME,
	.major = 0,		/* major/minor set at registration time per USE_DYNAMIC_MINOR */
	.minor = 0,
	.nr = 1,		/* one port */
	.cons = SAL_CONSOLE,
};

/**
 * sn_sal_init - When the kernel loads us, get us rolling w/ serial core
 *
 * Before this is called, we've been printing kernel messages in a special
 * early mode not making use of the serial core infrastructure.  When our
 * driver is loaded for real, we register the driver and port with serial
 * core and try to enable interrupt driven mode.
 *
 */
static int __init sn_sal_init(void)
{
	int retval;

	if (!ia64_platform_is("sn2"))
		return 0;

	printk(KERN_INFO "sn_console: Console driver init\n");

	if (USE_DYNAMIC_MINOR == 1) {
		misc.minor = MISC_DYNAMIC_MINOR;
		misc.name = DEVICE_NAME_DYNAMIC;
		retval = misc_register(&misc);
		if (retval != 0) {
			printk(KERN_WARNING "Failed to register console "
			       "device using misc_register.\n");
			return -ENODEV;
		}
		sal_console_uart.major = MISC_MAJOR;
		sal_console_uart.minor = misc.minor;
	} else {
		sal_console_uart.major = DEVICE_MAJOR;
		sal_console_uart.minor = DEVICE_MINOR;
	}

	/* We register the driver and the port before switching to interrupts
	 * or async above so the proper uart structures are populated */

	if (uart_register_driver(&sal_console_uart) < 0) {
		printk
		    ("ERROR sn_sal_init failed uart_register_driver, line %d\n",
		     __LINE__);
		return -ENODEV;
	}

	spin_lock_init(&sal_console_port.sc_port.lock);

	/* Setup the port struct with the minimum needed */
	sal_console_port.sc_port.membase = (char *)1;	/* just needs to be non-zero */
	sal_console_port.sc_port.type = PORT_16550A;
	sal_console_port.sc_port.fifosize = SN_SAL_MAX_CHARS;
	sal_console_port.sc_port.ops = &sn_console_ops;
	sal_console_port.sc_port.line = 0;

	if (uart_add_one_port(&sal_console_uart, &sal_console_port.sc_port) < 0) {
		/* error - not sure what I'd do - so I'll do nothing */
		printk(KERN_ERR "%s: unable to add port\n", __func__);
	}

	/* when this driver is compiled in, the console initialization
	 * will have already switched us into asynchronous operation
	 * before we get here through the initcalls */
	if (!sal_console_port.sc_is_asynch) {
		sn_sal_switch_to_asynch(&sal_console_port);
	}

	/* at this point (device_init) we can try to turn on interrupts */
	if (!IS_RUNNING_ON_SIMULATOR()) {
		sn_sal_switch_to_interrupts(&sal_console_port);
	}
	sn_process_input = 1;
	return 0;
}
device_initcall(sn_sal_init);

/**
 * puts_raw_fixed - sn_sal_console_write helper for adding \r's as required
 * @puts_raw : puts function to do the writing
 * @s: input string
 * @count: length
 *
 * We need a \r ahead of every \n for direct writes through
 * ia64_sn_console_putb (what sal_puts_raw below actually does).
 *
 */

static void puts_raw_fixed(int (*puts_raw) (const char *s, int len),
			   const char *s, int count)
{
	const char *s1;

	/* Output '\r' before each '\n' */
	while ((s1 = memchr(s, '\n', count)) != NULL) {
		puts_raw(s, s1 - s);
		puts_raw("\r\n", 2);
		count -= s1 + 1 - s;
		s = s1 + 1;
	}
	puts_raw(s, count);
}

/**
 * sn_sal_console_write - Print statements before serial core available
 * @console: Console to operate on - we ignore since we have just one
 * @s: String to send
 * @count: length
 *
 * This is referenced in the console struct.  It is used for early
 * console printing before we register with serial core and for things
 * such as kdb.  The console_lock must be held when we get here.
 *
 * This function has some code for trying to print output even if the lock
 * is held.  We try to cover the case where a lock holder could have died.
 * We don't use this special case code if we're not registered with serial
 * core yet.  After we're registered with serial core, the only time this
 * function would be used is for high level kernel output like magic sys req,
 * kdb, and printk's.
 */
static void
sn_sal_console_write(struct console *co, const char *s, unsigned count)
{
	unsigned long flags = 0;
	struct sn_cons_port *port = &sal_console_port;
	static int stole_lock = 0;

	BUG_ON(!port->sc_is_asynch);

	/* We can't look at the xmit buffer if we're not registered with serial core
	 *  yet.  So only do the fancy recovery after registering
	 */
	if (!port->sc_port.state) {
		/* Not yet registered with serial core - simple case */
		puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
		return;
	}

	/* somebody really wants this output, might be an
	 * oops, kdb, panic, etc.  make sure they get it. */
	if (!spin_trylock_irqsave(&port->sc_port.lock, flags)) {
		int lhead = port->sc_port.state->xmit.head;
		int ltail = port->sc_port.state->xmit.tail;
		int counter, got_lock = 0;

		/*
		 * We attempt to determine if someone has died with the
		 * lock. We wait ~20 secs after the head and tail ptrs
		 * stop moving and assume the lock holder is not functional
		 * and plow ahead. If the lock is freed within the time out
		 * period we re-get the lock and go ahead normally. We also
		 * remember if we have plowed ahead so that we don't have
		 * to wait out the time out period again - the asumption
		 * is that we will time out again.
		 */

		for (counter = 0; counter < 150; mdelay(125), counter++) {
			if (stole_lock)
				break;

			if (spin_trylock_irqsave(&port->sc_port.lock, flags)) {
				got_lock = 1;
				break;
			} else {
				/* still locked */
				if ((lhead != port->sc_port.state->xmit.head)
				    || (ltail !=
					port->sc_port.state->xmit.tail)) {
					lhead =
						port->sc_port.state->xmit.head;
					ltail =
						port->sc_port.state->xmit.tail;
					counter = 0;
				}
			}
		}
		/* flush anything in the serial core xmit buffer, raw */
		sn_transmit_chars(port, 1);
		if (got_lock) {
			spin_unlock_irqrestore(&port->sc_port.lock, flags);
			stole_lock = 0;
		} else {
			/* fell thru */
			stole_lock = 1;
		}
		puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
	} else {
		stole_lock = 0;
		sn_transmit_chars(port, 1);
		spin_unlock_irqrestore(&port->sc_port.lock, flags);

		puts_raw_fixed(port->sc_ops->sal_puts_raw, s, count);
	}
}


/**
 * sn_sal_console_setup - Set up console for early printing
 * @co: Console to work with
 * @options: Options to set
 *
 * Altix console doesn't do anything with baud rates, etc, anyway.
 *
 * This isn't required since not providing the setup function in the
 * console struct is ok.  However, other patches like KDB plop something
 * here so providing it is easier.
 *
 */
static int sn_sal_console_setup(struct console *co, char *options)
{
	return 0;
}

/**
 * sn_sal_console_write_early - simple early output routine
 * @co - console struct
 * @s - string to print
 * @count - count
 *
 * Simple function to provide early output, before even
 * sn_sal_serial_console_init is called.  Referenced in the
 * console struct registerd in sn_serial_console_early_setup.
 *
 */
static void __init
sn_sal_console_write_early(struct console *co, const char *s, unsigned count)
{
	puts_raw_fixed(sal_console_port.sc_ops->sal_puts_raw, s, count);
}

/* Used for very early console printing - again, before
 * sn_sal_serial_console_init is run */
static struct console sal_console_early __initdata = {
	.name = "sn_sal",
	.write = sn_sal_console_write_early,
	.flags = CON_PRINTBUFFER,
	.index = -1,
};

/**
 * sn_serial_console_early_setup - Sets up early console output support
 *
 * Register a console early on...  This is for output before even
 * sn_sal_serial_cosnole_init is called.  This function is called from
 * setup.c.  This allows us to do really early polled writes. When
 * sn_sal_serial_console_init is called, this console is unregistered
 * and a new one registered.
 */
int __init sn_serial_console_early_setup(void)
{
	if (!ia64_platform_is("sn2"))
		return -1;

	sal_console_port.sc_ops = &poll_ops;
	spin_lock_init(&sal_console_port.sc_port.lock);
	early_sn_setup();	/* Find SAL entry points */
	register_console(&sal_console_early);

	return 0;
}

/**
 * sn_sal_serial_console_init - Early console output - set up for register
 *
 * This function is called when regular console init happens.  Because we
 * support even earlier console output with sn_serial_console_early_setup
 * (called from setup.c directly), this function unregisters the really
 * early console.
 *
 * Note: Even if setup.c doesn't register sal_console_early, unregistering
 * it here doesn't hurt anything.
 *
 */
static int __init sn_sal_serial_console_init(void)
{
	if (ia64_platform_is("sn2")) {
		sn_sal_switch_to_asynch(&sal_console_port);
		DPRINTF("sn_sal_serial_console_init : register console\n");
		register_console(&sal_console);
		unregister_console(&sal_console_early);
	}
	return 0;
}

console_initcall(sn_sal_serial_console_init);