summaryrefslogtreecommitdiff
path: root/drivers/char/generic_serial.c
blob: 4711d9b3a59545f870d769f4818f967923bf21a9 (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
/*
 *  generic_serial.c
 *
 *  Copyright (C) 1998/1999 R.E.Wolff@BitWizard.nl
 *
 *  written for the SX serial driver.
 *     Contains the code that should be shared over all the serial drivers.
 *
 *  Credit for the idea to do it this way might go to Alan Cox. 
 *
 *
 *  Version 0.1 -- December, 1998. Initial version.
 *  Version 0.2 -- March, 1999.    Some more routines. Bugfixes. Etc.
 *  Version 0.5 -- August, 1999.   Some more fixes. Reformat for Linus.
 *
 *  BitWizard is actively maintaining this file. We sometimes find
 *  that someone submitted changes to this file. We really appreciate
 *  your help, but please submit changes through us. We're doing our
 *  best to be responsive.  -- REW
 * */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/tty.h>
#include <linux/serial.h>
#include <linux/mm.h>
#include <linux/generic_serial.h>
#include <linux/interrupt.h>
#include <linux/tty_flip.h>
#include <linux/delay.h>
#include <asm/semaphore.h>
#include <asm/uaccess.h>

#define DEBUG 

static char *                  tmp_buf; 

static int gs_debug;

#ifdef DEBUG
#define gs_dprintk(f, str...) if (gs_debug & f) printk (str)
#else
#define gs_dprintk(f, str...) /* nothing */
#endif

#define func_enter() gs_dprintk (GS_DEBUG_FLOW, "gs: enter %s\n", __FUNCTION__)
#define func_exit()  gs_dprintk (GS_DEBUG_FLOW, "gs: exit  %s\n", __FUNCTION__)
#define NEW_WRITE_LOCKING 1
#if NEW_WRITE_LOCKING
#define DECL      /* Nothing */
#define LOCKIT    mutex_lock(& port->port_write_mutex);
#define RELEASEIT mutex_unlock(&port->port_write_mutex);
#else
#define DECL      unsigned long flags;
#define LOCKIT    save_flags (flags);cli ()
#define RELEASEIT restore_flags (flags)
#endif

#define RS_EVENT_WRITE_WAKEUP	1

module_param(gs_debug, int, 0644);


void gs_put_char(struct tty_struct * tty, unsigned char ch)
{
	struct gs_port *port;
	DECL

	func_enter (); 

	if (!tty) return;

	port = tty->driver_data;

	if (!port) return;

	if (! (port->flags & ASYNC_INITIALIZED)) return;

	/* Take a lock on the serial tranmit buffer! */
	LOCKIT;

	if (port->xmit_cnt >= SERIAL_XMIT_SIZE - 1) {
		/* Sorry, buffer is full, drop character. Update statistics???? -- REW */
		RELEASEIT;
		return;
	}

	port->xmit_buf[port->xmit_head++] = ch;
	port->xmit_head &= SERIAL_XMIT_SIZE - 1;
	port->xmit_cnt++;  /* Characters in buffer */

	RELEASEIT;
	func_exit ();
}


#ifdef NEW_WRITE_LOCKING

/*
> Problems to take into account are:
>       -1- Interrupts that empty part of the buffer.
>       -2- page faults on the access to userspace. 
>       -3- Other processes that are also trying to do a "write". 
*/

int gs_write(struct tty_struct * tty, 
                    const unsigned char *buf, int count)
{
	struct gs_port *port;
	int c, total = 0;
	int t;

	func_enter ();

	if (!tty) return 0;

	port = tty->driver_data;

	if (!port) return 0;

	if (! (port->flags & ASYNC_INITIALIZED))
		return 0;

	/* get exclusive "write" access to this port (problem 3) */
	/* This is not a spinlock because we can have a disk access (page 
		 fault) in copy_from_user */
	mutex_lock(& port->port_write_mutex);

	while (1) {

		c = count;
 
		/* This is safe because we "OWN" the "head". Noone else can 
		   change the "head": we own the port_write_mutex. */
		/* Don't overrun the end of the buffer */
		t = SERIAL_XMIT_SIZE - port->xmit_head;
		if (t < c) c = t;
 
		/* This is safe because the xmit_cnt can only decrease. This 
		   would increase "t", so we might copy too little chars. */
		/* Don't copy past the "head" of the buffer */
		t = SERIAL_XMIT_SIZE - 1 - port->xmit_cnt;
		if (t < c) c = t;
 
		/* Can't copy more? break out! */
		if (c <= 0) break;

		memcpy (port->xmit_buf + port->xmit_head, buf, c);

		port -> xmit_cnt += c;
		port -> xmit_head = (port->xmit_head + c) & (SERIAL_XMIT_SIZE -1);
		buf += c;
		count -= c;
		total += c;
	}
	mutex_unlock(& port->port_write_mutex);

	gs_dprintk (GS_DEBUG_WRITE, "write: interrupts are %s\n", 
	            (port->flags & GS_TX_INTEN)?"enabled": "disabled"); 

	if (port->xmit_cnt && 
	    !tty->stopped && 
	    !tty->hw_stopped &&
	    !(port->flags & GS_TX_INTEN)) {
		port->flags |= GS_TX_INTEN;
		port->rd->enable_tx_interrupts (port);
	}
	func_exit ();
	return total;
}
#else
/*
> Problems to take into account are:
>       -1- Interrupts that empty part of the buffer.
>       -2- page faults on the access to userspace. 
>       -3- Other processes that are also trying to do a "write". 
*/

int gs_write(struct tty_struct * tty,
                    const unsigned char *buf, int count)
{
	struct gs_port *port;
	int c, total = 0;
	int t;
	unsigned long flags;

	func_enter ();

	/* The standard serial driver returns 0 in this case. 
	   That sounds to me as "No error, I just didn't get to writing any
	   bytes. Feel free to try again." 
	   The "official" way to write n bytes from buf is:

		 for (nwritten = 0;nwritten < n;nwritten += rv) {
			 rv = write (fd, buf+nwritten, n-nwritten);
			 if (rv < 0) break; // Error: bail out. //
		 } 

	   which will loop endlessly in this case. The manual page for write
	   agrees with me. In practise almost everybody writes 
	   "write (fd, buf,n);" but some people might have had to deal with 
	   incomplete writes in the past and correctly implemented it by now... 
	 */

	if (!tty) return -EIO;

	port = tty->driver_data;
	if (!port || !port->xmit_buf || !tmp_buf)
		return -EIO;

	local_save_flags(flags);
	while (1) {
		cli();
		c = count;

		/* This is safe because we "OWN" the "head". Noone else can 
		   change the "head": we own the port_write_mutex. */
		/* Don't overrun the end of the buffer */
		t = SERIAL_XMIT_SIZE - port->xmit_head;
		if (t < c) c = t;

		/* This is safe because the xmit_cnt can only decrease. This 
		   would increase "t", so we might copy too little chars. */
		/* Don't copy past the "head" of the buffer */
		t = SERIAL_XMIT_SIZE - 1 - port->xmit_cnt;
		if (t < c) c = t;

		/* Can't copy more? break out! */
		if (c <= 0) {
			local_restore_flags(flags);
			break;
		}
		memcpy(port->xmit_buf + port->xmit_head, buf, c);
		port->xmit_head = ((port->xmit_head + c) &
		                   (SERIAL_XMIT_SIZE-1));
		port->xmit_cnt += c;
		local_restore_flags(flags);
		buf += c;
		count -= c;
		total += c;
	}

	if (port->xmit_cnt && 
	    !tty->stopped && 
	    !tty->hw_stopped &&
	    !(port->flags & GS_TX_INTEN)) {
		port->flags |= GS_TX_INTEN;
		port->rd->enable_tx_interrupts (port);
	}
	func_exit ();
	return total;
}

#endif



int gs_write_room(struct tty_struct * tty)
{
	struct gs_port *port = tty->driver_data;
	int ret;

	func_enter ();
	ret = SERIAL_XMIT_SIZE - port->xmit_cnt - 1;
	if (ret < 0)
		ret = 0;
	func_exit ();
	return ret;
}


int gs_chars_in_buffer(struct tty_struct *tty)
{
	struct gs_port *port = tty->driver_data;
	func_enter ();

	func_exit ();
	return port->xmit_cnt;
}


static int gs_real_chars_in_buffer(struct tty_struct *tty)
{
	struct gs_port *port;
	func_enter ();

	if (!tty) return 0;
	port = tty->driver_data;

	if (!port->rd) return 0;
	if (!port->rd->chars_in_buffer) return 0;

	func_exit ();
	return port->xmit_cnt + port->rd->chars_in_buffer (port);
}


static int gs_wait_tx_flushed (void * ptr, unsigned long timeout) 
{
	struct gs_port *port = ptr;
	unsigned long end_jiffies;
	int jiffies_to_transmit, charsleft = 0, rv = 0;
	int rcib;

	func_enter();

	gs_dprintk (GS_DEBUG_FLUSH, "port=%p.\n", port);
	if (port) {
		gs_dprintk (GS_DEBUG_FLUSH, "xmit_cnt=%x, xmit_buf=%p, tty=%p.\n", 
		port->xmit_cnt, port->xmit_buf, port->tty);
	}

	if (!port || port->xmit_cnt < 0 || !port->xmit_buf) {
		gs_dprintk (GS_DEBUG_FLUSH, "ERROR: !port, !port->xmit_buf or prot->xmit_cnt < 0.\n");
		func_exit();
		return -EINVAL;  /* This is an error which we don't know how to handle. */
	}

	rcib = gs_real_chars_in_buffer(port->tty);

	if(rcib <= 0) {
		gs_dprintk (GS_DEBUG_FLUSH, "nothing to wait for.\n");
		func_exit();
		return rv;
	}
	/* stop trying: now + twice the time it would normally take +  seconds */
	if (timeout == 0) timeout = MAX_SCHEDULE_TIMEOUT;
	end_jiffies  = jiffies; 
	if (timeout !=  MAX_SCHEDULE_TIMEOUT)
		end_jiffies += port->baud?(2 * rcib * 10 * HZ / port->baud):0;
	end_jiffies += timeout;

	gs_dprintk (GS_DEBUG_FLUSH, "now=%lx, end=%lx (%ld).\n", 
		    jiffies, end_jiffies, end_jiffies-jiffies); 

	/* the expression is actually jiffies < end_jiffies, but that won't
	   work around the wraparound. Tricky eh? */
	while ((charsleft = gs_real_chars_in_buffer (port->tty)) &&
	        time_after (end_jiffies, jiffies)) {
		/* Units check: 
		   chars * (bits/char) * (jiffies /sec) / (bits/sec) = jiffies!
		   check! */

		charsleft += 16; /* Allow 16 chars more to be transmitted ... */
		jiffies_to_transmit = port->baud?(1 + charsleft * 10 * HZ / port->baud):0;
		/*                                ^^^ Round up.... */
		if (jiffies_to_transmit <= 0) jiffies_to_transmit = 1;

		gs_dprintk (GS_DEBUG_FLUSH, "Expect to finish in %d jiffies "
			    "(%d chars).\n", jiffies_to_transmit, charsleft); 

		msleep_interruptible(jiffies_to_msecs(jiffies_to_transmit));
		if (signal_pending (current)) {
			gs_dprintk (GS_DEBUG_FLUSH, "Signal pending. Bombing out: "); 
			rv = -EINTR;
			break;
		}
	}

	gs_dprintk (GS_DEBUG_FLUSH, "charsleft = %d.\n", charsleft); 
	set_current_state (TASK_RUNNING);

	func_exit();
	return rv;
}



void gs_flush_buffer(struct tty_struct *tty)
{
	struct gs_port *port;
	unsigned long flags;

	func_enter ();

	if (!tty) return;

	port = tty->driver_data;

	if (!port) return;

	/* XXX Would the write semaphore do? */
	spin_lock_irqsave (&port->driver_lock, flags);
	port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
	spin_unlock_irqrestore (&port->driver_lock, flags);

	wake_up_interruptible(&tty->write_wait);
	tty_wakeup(tty);
	func_exit ();
}


void gs_flush_chars(struct tty_struct * tty)
{
	struct gs_port *port;

	func_enter ();

	if (!tty) return;

	port = tty->driver_data;

	if (!port) return;

	if (port->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
	    !port->xmit_buf) {
		func_exit ();
		return;
	}

	/* Beats me -- REW */
	port->flags |= GS_TX_INTEN;
	port->rd->enable_tx_interrupts (port);
	func_exit ();
}


void gs_stop(struct tty_struct * tty)
{
	struct gs_port *port;

	func_enter ();

	if (!tty) return;

	port = tty->driver_data;

	if (!port) return;

	if (port->xmit_cnt && 
	    port->xmit_buf && 
	    (port->flags & GS_TX_INTEN) ) {
		port->flags &= ~GS_TX_INTEN;
		port->rd->disable_tx_interrupts (port);
	}
	func_exit ();
}


void gs_start(struct tty_struct * tty)
{
	struct gs_port *port;

	if (!tty) return;

	port = tty->driver_data;

	if (!port) return;

	if (port->xmit_cnt && 
	    port->xmit_buf && 
	    !(port->flags & GS_TX_INTEN) ) {
		port->flags |= GS_TX_INTEN;
		port->rd->enable_tx_interrupts (port);
	}
	func_exit ();
}


static void gs_shutdown_port (struct gs_port *port)
{
	unsigned long flags;

	func_enter();
	
	if (!port) return;
	
	if (!(port->flags & ASYNC_INITIALIZED))
		return;

	spin_lock_irqsave(&port->driver_lock, flags);

	if (port->xmit_buf) {
		free_page((unsigned long) port->xmit_buf);
		port->xmit_buf = NULL;
	}

	if (port->tty)
		set_bit(TTY_IO_ERROR, &port->tty->flags);

	port->rd->shutdown_port (port);

	port->flags &= ~ASYNC_INITIALIZED;
	spin_unlock_irqrestore(&port->driver_lock, flags);

	func_exit();
}


void gs_hangup(struct tty_struct *tty)
{
	struct gs_port   *port;

	func_enter ();

	if (!tty) return;

	port = tty->driver_data;
	tty = port->tty;
	if (!tty) 
		return;

	gs_shutdown_port (port);
	port->flags &= ~(ASYNC_NORMAL_ACTIVE|GS_ACTIVE);
	port->tty = NULL;
	port->count = 0;

	wake_up_interruptible(&port->open_wait);
	func_exit ();
}


int gs_block_til_ready(void *port_, struct file * filp)
{
	struct gs_port *port = port_;
	DECLARE_WAITQUEUE(wait, current);
	int    retval;
	int    do_clocal = 0;
	int    CD;
	struct tty_struct *tty;
	unsigned long flags;

	func_enter ();

	if (!port) return 0;

	tty = port->tty;

	if (!tty) return 0;

	gs_dprintk (GS_DEBUG_BTR, "Entering gs_block_till_ready.\n"); 
	/*
	 * If the device is in the middle of being closed, then block
	 * until it's done, and then try again.
	 */
	if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
		interruptible_sleep_on(&port->close_wait);
		if (port->flags & ASYNC_HUP_NOTIFY)
			return -EAGAIN;
		else
			return -ERESTARTSYS;
	}

	gs_dprintk (GS_DEBUG_BTR, "after hung up\n"); 

	/*
	 * If non-blocking mode is set, or the port is not enabled,
	 * then make the check up front and then exit.
	 */
	if ((filp->f_flags & O_NONBLOCK) ||
	    (tty->flags & (1 << TTY_IO_ERROR))) {
		port->flags |= ASYNC_NORMAL_ACTIVE;
		return 0;
	}

	gs_dprintk (GS_DEBUG_BTR, "after nonblock\n"); 
 
	if (C_CLOCAL(tty))
		do_clocal = 1;

	/*
	 * Block waiting for the carrier detect and the line to become
	 * free (i.e., not in use by the callout).  While we are in
	 * this loop, port->count is dropped by one, so that
	 * rs_close() knows when to free things.  We restore it upon
	 * exit, either normal or abnormal.
	 */
	retval = 0;

	add_wait_queue(&port->open_wait, &wait);

	gs_dprintk (GS_DEBUG_BTR, "after add waitq.\n"); 
	spin_lock_irqsave(&port->driver_lock, flags);
	if (!tty_hung_up_p(filp)) {
		port->count--;
	}
	spin_unlock_irqrestore(&port->driver_lock, flags);
	port->blocked_open++;
	while (1) {
		CD = port->rd->get_CD (port);
		gs_dprintk (GS_DEBUG_BTR, "CD is now %d.\n", CD);
		set_current_state (TASK_INTERRUPTIBLE);
		if (tty_hung_up_p(filp) ||
		    !(port->flags & ASYNC_INITIALIZED)) {
			if (port->flags & ASYNC_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;
			break;
		}
		if (!(port->flags & ASYNC_CLOSING) &&
		    (do_clocal || CD))
			break;
		gs_dprintk (GS_DEBUG_BTR, "signal_pending is now: %d (%lx)\n", 
		(int)signal_pending (current), *(long*)(&current->blocked)); 
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
		schedule();
	}
	gs_dprintk (GS_DEBUG_BTR, "Got out of the loop. (%d)\n",
		    port->blocked_open);
	set_current_state (TASK_RUNNING);
	remove_wait_queue(&port->open_wait, &wait);
	if (!tty_hung_up_p(filp)) {
		port->count++;
	}
	port->blocked_open--;
	if (retval)
		return retval;

	port->flags |= ASYNC_NORMAL_ACTIVE;
	func_exit ();
	return 0;
}			 


void gs_close(struct tty_struct * tty, struct file * filp)
{
	unsigned long flags;
	struct gs_port *port;
	
	func_enter ();

	if (!tty) return;

	port = (struct gs_port *) tty->driver_data;

	if (!port) return;

	if (!port->tty) {
		/* This seems to happen when this is called from vhangup. */
		gs_dprintk (GS_DEBUG_CLOSE, "gs: Odd: port->tty is NULL\n");
		port->tty = tty;
	}

	spin_lock_irqsave(&port->driver_lock, flags);

	if (tty_hung_up_p(filp)) {
		spin_unlock_irqrestore(&port->driver_lock, flags);
		if (port->rd->hungup)
			port->rd->hungup (port);
		func_exit ();
		return;
	}

	if ((tty->count == 1) && (port->count != 1)) {
		printk(KERN_ERR "gs: gs_close port %p: bad port count;"
		       " tty->count is 1, port count is %d\n", port, port->count);
		port->count = 1;
	}
	if (--port->count < 0) {
		printk(KERN_ERR "gs: gs_close port %p: bad port count: %d\n", port, port->count);
		port->count = 0;
	}

	if (port->count) {
		gs_dprintk(GS_DEBUG_CLOSE, "gs_close port %p: count: %d\n", port, port->count);
		spin_unlock_irqrestore(&port->driver_lock, flags);
		func_exit ();
		return;
	}
	port->flags |= ASYNC_CLOSING;

	/*
	 * Now we wait for the transmit buffer to clear; and we notify 
	 * the line discipline to only process XON/XOFF characters.
	 */
	tty->closing = 1;
	/* if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
	   tty_wait_until_sent(tty, port->closing_wait); */

	/*
	 * At this point we stop accepting input.  To do this, we
	 * disable the receive line status interrupts, and tell the
	 * interrupt driver to stop checking the data ready bit in the
	 * line status register.
	 */

	port->rd->disable_rx_interrupts (port);
	spin_unlock_irqrestore(&port->driver_lock, flags);

	/* close has no way of returning "EINTR", so discard return value */
	if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
		gs_wait_tx_flushed (port, port->closing_wait);

	port->flags &= ~GS_ACTIVE;

	if (tty->driver->flush_buffer)
		tty->driver->flush_buffer(tty);

	tty_ldisc_flush(tty);
	tty->closing = 0;

	port->event = 0;
	port->rd->close (port);
	port->rd->shutdown_port (port);
	port->tty = NULL;

	if (port->blocked_open) {
		if (port->close_delay) {
			spin_unlock_irqrestore(&port->driver_lock, flags);
			msleep_interruptible(jiffies_to_msecs(port->close_delay));
			spin_lock_irqsave(&port->driver_lock, flags);
		}
		wake_up_interruptible(&port->open_wait);
	}
	port->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING | ASYNC_INITIALIZED);
	wake_up_interruptible(&port->close_wait);

	func_exit ();
}


static unsigned int     gs_baudrates[] = {
  0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
  9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600
};


void gs_set_termios (struct tty_struct * tty, 
                     struct termios * old_termios)
{
	struct gs_port *port;
	int baudrate, tmp, rv;
	struct termios *tiosp;

	func_enter();

	if (!tty) return;

	port = tty->driver_data;

	if (!port) return;
	if (!port->tty) {
		/* This seems to happen when this is called after gs_close. */
		gs_dprintk (GS_DEBUG_TERMIOS, "gs: Odd: port->tty is NULL\n");
		port->tty = tty;
	}


	tiosp = tty->termios;

	if (gs_debug & GS_DEBUG_TERMIOS) {
		gs_dprintk (GS_DEBUG_TERMIOS, "termios structure (%p):\n", tiosp);
	}

	/* This is an optimization that is only allowed for dumb cards */
	/* Smart cards require knowledge of iflags and oflags too: that 
	   might change hardware cooking mode.... */
	if (old_termios) {
		if(   (tiosp->c_iflag == old_termios->c_iflag)
		   && (tiosp->c_oflag == old_termios->c_oflag)
		   && (tiosp->c_cflag == old_termios->c_cflag)
		   && (tiosp->c_lflag == old_termios->c_lflag)
		   && (tiosp->c_line  == old_termios->c_line)
		   && (memcmp(tiosp->c_cc, old_termios->c_cc, NCC) == 0)) {
			gs_dprintk(GS_DEBUG_TERMIOS, "gs_set_termios: optimized away\n");
			return /* 0 */;
		}
	} else 
		gs_dprintk(GS_DEBUG_TERMIOS, "gs_set_termios: no old_termios: "
		           "no optimization\n");

	if(old_termios && (gs_debug & GS_DEBUG_TERMIOS)) {
		if(tiosp->c_iflag != old_termios->c_iflag)  printk("c_iflag changed\n");
		if(tiosp->c_oflag != old_termios->c_oflag)  printk("c_oflag changed\n");
		if(tiosp->c_cflag != old_termios->c_cflag)  printk("c_cflag changed\n");
		if(tiosp->c_lflag != old_termios->c_lflag)  printk("c_lflag changed\n");
		if(tiosp->c_line  != old_termios->c_line)   printk("c_line changed\n");
		if(!memcmp(tiosp->c_cc, old_termios->c_cc, NCC)) printk("c_cc changed\n");
	}

	baudrate = tty_get_baud_rate(tty);

	baudrate = gs_baudrates[baudrate];
	if ((tiosp->c_cflag & CBAUD) == B38400) {
		if (     (port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
			baudrate = 57600;
		else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
			baudrate = 115200;
		else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
			baudrate = 230400;
		else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
			baudrate = 460800;
		else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST)
			baudrate = (port->baud_base / port->custom_divisor);
	}

	/* I recommend using THIS instead of the mess in termios (and
	   duplicating the above code). Next we should create a clean
	   interface towards this variable. If your card supports arbitrary
	   baud rates, (e.g. CD1400 or 16550 based cards) then everything
	   will be very easy..... */
	port->baud = baudrate;

	/* Two timer ticks seems enough to wakeup something like SLIP driver */
	/* Baudrate/10 is cps. Divide by HZ to get chars per tick. */
	tmp = (baudrate / 10 / HZ) * 2;			 

	if (tmp <                 0) tmp = 0;
	if (tmp >= SERIAL_XMIT_SIZE) tmp = SERIAL_XMIT_SIZE-1;

	port->wakeup_chars = tmp;

	/* We should really wait for the characters to be all sent before
	   changing the settings. -- CAL */
	rv = gs_wait_tx_flushed (port, MAX_SCHEDULE_TIMEOUT);
	if (rv < 0) return /* rv */;

	rv = port->rd->set_real_termios(port);
	if (rv < 0) return /* rv */;

	if ((!old_termios || 
	     (old_termios->c_cflag & CRTSCTS)) &&
	    !(      tiosp->c_cflag & CRTSCTS)) {
		tty->stopped = 0;
		gs_start(tty);
	}

#ifdef tytso_patch_94Nov25_1726
	/* This "makes sense", Why is it commented out? */

	if (!(old_termios->c_cflag & CLOCAL) &&
	    (tty->termios->c_cflag & CLOCAL))
		wake_up_interruptible(&port->gs.open_wait);
#endif

	func_exit();
	return /* 0 */;
}



/* Must be called with interrupts enabled */
int gs_init_port(struct gs_port *port)
{
	unsigned long flags;
	unsigned long page;

	func_enter ();

        if (!tmp_buf) {
		page = get_zeroed_page(GFP_KERNEL);
		spin_lock_irqsave (&port->driver_lock, flags); /* Don't expect this to make a difference. */
		if (tmp_buf)
			free_page(page);
		else
			tmp_buf = (unsigned char *) page;
		spin_unlock_irqrestore (&port->driver_lock, flags);
		if (!tmp_buf) {
			func_exit ();
			return -ENOMEM;
		}
	}

	if (port->flags & ASYNC_INITIALIZED) {
		func_exit ();
		return 0;
	}
	if (!port->xmit_buf) {
		/* We may sleep in get_zeroed_page() */
		unsigned long tmp;

		tmp = get_zeroed_page(GFP_KERNEL);
		spin_lock_irqsave (&port->driver_lock, flags);
		if (port->xmit_buf) 
			free_page (tmp);
		else
			port->xmit_buf = (unsigned char *) tmp;
		spin_unlock_irqrestore(&port->driver_lock, flags);
		if (!port->xmit_buf) {
			func_exit ();
			return -ENOMEM;
		}
	}

	spin_lock_irqsave (&port->driver_lock, flags);
	if (port->tty) 
		clear_bit(TTY_IO_ERROR, &port->tty->flags);
	mutex_init(&port->port_write_mutex);
	port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
	spin_unlock_irqrestore(&port->driver_lock, flags);
	gs_set_termios(port->tty, NULL);
	spin_lock_irqsave (&port->driver_lock, flags);
	port->flags |= ASYNC_INITIALIZED;
	port->flags &= ~GS_TX_INTEN;

	spin_unlock_irqrestore(&port->driver_lock, flags);
	func_exit ();
	return 0;
}


int gs_setserial(struct gs_port *port, struct serial_struct __user *sp)
{
	struct serial_struct sio;

	if (copy_from_user(&sio, sp, sizeof(struct serial_struct)))
		return(-EFAULT);

	if (!capable(CAP_SYS_ADMIN)) {
		if ((sio.baud_base != port->baud_base) ||
		    (sio.close_delay != port->close_delay) ||
		    ((sio.flags & ~ASYNC_USR_MASK) !=
		     (port->flags & ~ASYNC_USR_MASK)))
			return(-EPERM);
	} 

	port->flags = (port->flags & ~ASYNC_USR_MASK) |
		(sio.flags & ASYNC_USR_MASK);
  
	port->baud_base = sio.baud_base;
	port->close_delay = sio.close_delay;
	port->closing_wait = sio.closing_wait;
	port->custom_divisor = sio.custom_divisor;

	gs_set_termios (port->tty, NULL);

	return 0;
}


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

/*
 *      Generate the serial struct info.
 */

int gs_getserial(struct gs_port *port, struct serial_struct __user *sp)
{
	struct serial_struct    sio;

	memset(&sio, 0, sizeof(struct serial_struct));
	sio.flags = port->flags;
	sio.baud_base = port->baud_base;
	sio.close_delay = port->close_delay;
	sio.closing_wait = port->closing_wait;
	sio.custom_divisor = port->custom_divisor;
	sio.hub6 = 0;

	/* If you want you can override these. */
	sio.type = PORT_UNKNOWN;
	sio.xmit_fifo_size = -1;
	sio.line = -1;
	sio.port = -1;
	sio.irq = -1;

	if (port->rd->getserial)
		port->rd->getserial (port, &sio);

	if (copy_to_user(sp, &sio, sizeof(struct serial_struct)))
		return -EFAULT;
	return 0;

}


void gs_got_break(struct gs_port *port)
{
	func_enter ();

	tty_insert_flip_char(port->tty, 0, TTY_BREAK);
	tty_schedule_flip(port->tty);
	if (port->flags & ASYNC_SAK) {
		do_SAK (port->tty);
	}

	func_exit ();
}


EXPORT_SYMBOL(gs_put_char);
EXPORT_SYMBOL(gs_write);
EXPORT_SYMBOL(gs_write_room);
EXPORT_SYMBOL(gs_chars_in_buffer);
EXPORT_SYMBOL(gs_flush_buffer);
EXPORT_SYMBOL(gs_flush_chars);
EXPORT_SYMBOL(gs_stop);
EXPORT_SYMBOL(gs_start);
EXPORT_SYMBOL(gs_hangup);
EXPORT_SYMBOL(gs_block_til_ready);
EXPORT_SYMBOL(gs_close);
EXPORT_SYMBOL(gs_set_termios);
EXPORT_SYMBOL(gs_init_port);
EXPORT_SYMBOL(gs_setserial);
EXPORT_SYMBOL(gs_getserial);
EXPORT_SYMBOL(gs_got_break);

MODULE_LICENSE("GPL");