aboutsummaryrefslogtreecommitdiff
path: root/drivers/parport/ieee1284.c
blob: f12b9da692551c6e204e16d74e06aa9d4e593c99 (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
/*
 * IEEE-1284 implementation for parport.
 *
 * Authors: Phil Blundell <philb@gnu.org>
 *          Carsten Gross <carsten@sol.wohnheim.uni-ulm.de>
 *	    Jose Renau <renau@acm.org>
 *          Tim Waugh <tim@cyberelk.demon.co.uk> (largely rewritten)
 *
 * This file is responsible for IEEE 1284 negotiation, and for handing
 * read/write requests to low-level drivers.
 *
 * Any part of this program may be used in documents licensed under
 * the GNU Free Documentation License, Version 1.1 or any later version
 * published by the Free Software Foundation.
 *
 * Various hacks, Fred Barnes <frmb2@ukc.ac.uk>, 04/2000
 */

#include <linux/module.h>
#include <linux/threads.h>
#include <linux/parport.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/sched/signal.h>

#undef DEBUG /* undef me for production */

#ifdef CONFIG_LP_CONSOLE
#undef DEBUG /* Don't want a garbled console */
#endif

#ifdef DEBUG
#define DPRINTK(stuff...) printk (stuff)
#else
#define DPRINTK(stuff...)
#endif

/* Make parport_wait_peripheral wake up.
 * It will be useful to call this from an interrupt handler. */
static void parport_ieee1284_wakeup (struct parport *port)
{
	up (&port->physport->ieee1284.irq);
}

static void timeout_waiting_on_port (struct timer_list *t)
{
	struct parport *port = from_timer(port, t, timer);

	parport_ieee1284_wakeup (port);
}

/**
 *	parport_wait_event - wait for an event on a parallel port
 *	@port: port to wait on
 *	@timeout: time to wait (in jiffies)
 *
 *	This function waits for up to @timeout jiffies for an
 *	interrupt to occur on a parallel port.  If the port timeout is
 *	set to zero, it returns immediately.
 *
 *	If an interrupt occurs before the timeout period elapses, this
 *	function returns zero immediately.  If it times out, it returns
 *	one.  An error code less than zero indicates an error (most
 *	likely a pending signal), and the calling code should finish
 *	what it's doing as soon as it can.
 */

int parport_wait_event (struct parport *port, signed long timeout)
{
	int ret;

	if (!port->physport->cad->timeout)
		/* Zero timeout is special, and we can't down() the
		   semaphore. */
		return 1;

	timer_setup(&port->timer, timeout_waiting_on_port, 0);
	mod_timer(&port->timer, jiffies + timeout);
	ret = down_interruptible (&port->physport->ieee1284.irq);
	if (!del_timer_sync(&port->timer) && !ret)
		/* Timed out. */
		ret = 1;

	return ret;
}

/**
 *	parport_poll_peripheral - poll status lines
 *	@port: port to watch
 *	@mask: status lines to watch
 *	@result: desired values of chosen status lines
 *	@usec: timeout
 *
 *	This function busy-waits until the masked status lines have
 *	the desired values, or until the timeout period elapses.  The
 *	@mask and @result parameters are bitmasks, with the bits
 *	defined by the constants in parport.h: %PARPORT_STATUS_BUSY,
 *	and so on.
 *
 *	This function does not call schedule(); instead it busy-waits
 *	using udelay().  It currently has a resolution of 5usec.
 *
 *	If the status lines take on the desired values before the
 *	timeout period elapses, parport_poll_peripheral() returns zero
 *	immediately.  A return value greater than zero indicates
 *	a timeout.  An error code (less than zero) indicates an error,
 *	most likely a signal that arrived, and the caller should
 *	finish what it is doing as soon as possible.
*/

int parport_poll_peripheral(struct parport *port,
			    unsigned char mask,
			    unsigned char result,
			    int usec)
{
	/* Zero return code is success, >0 is timeout. */
	int count = usec / 5 + 2;
	int i;
	unsigned char status;
	for (i = 0; i < count; i++) {
		status = parport_read_status (port);
		if ((status & mask) == result)
			return 0;
		if (signal_pending (current))
			return -EINTR;
		if (need_resched())
			break;
		if (i >= 2)
			udelay (5);
	}

	return 1;
}

/**
 *	parport_wait_peripheral - wait for status lines to change in 35ms
 *	@port: port to watch
 *	@mask: status lines to watch
 *	@result: desired values of chosen status lines
 *
 *	This function waits until the masked status lines have the
 *	desired values, or until 35ms have elapsed (see IEEE 1284-1994
 *	page 24 to 25 for why this value in particular is hardcoded).
 *	The @mask and @result parameters are bitmasks, with the bits
 *	defined by the constants in parport.h: %PARPORT_STATUS_BUSY,
 *	and so on.
 *
 *	The port is polled quickly to start off with, in anticipation
 *	of a fast response from the peripheral.  This fast polling
 *	time is configurable (using /proc), and defaults to 500usec.
 *	If the timeout for this port (see parport_set_timeout()) is
 *	zero, the fast polling time is 35ms, and this function does
 *	not call schedule().
 *
 *	If the timeout for this port is non-zero, after the fast
 *	polling fails it uses parport_wait_event() to wait for up to
 *	10ms, waking up if an interrupt occurs.
 */

int parport_wait_peripheral(struct parport *port,
			    unsigned char mask, 
			    unsigned char result)
{
	int ret;
	int usec;
	unsigned long deadline;
	unsigned char status;

	usec = port->physport->spintime; /* usecs of fast polling */
	if (!port->physport->cad->timeout)
		/* A zero timeout is "special": busy wait for the
		   entire 35ms. */
		usec = 35000;

	/* Fast polling.
	 *
	 * This should be adjustable.
	 * How about making a note (in the device structure) of how long
	 * it takes, so we know for next time?
	 */
	ret = parport_poll_peripheral (port, mask, result, usec);
	if (ret != 1)
		return ret;

	if (!port->physport->cad->timeout)
		/* We may be in an interrupt handler, so we can't poll
		 * slowly anyway. */
		return 1;

	/* 40ms of slow polling. */
	deadline = jiffies + msecs_to_jiffies(40);
	while (time_before (jiffies, deadline)) {
		if (signal_pending (current))
			return -EINTR;

		/* Wait for 10ms (or until an interrupt occurs if
		 * the handler is set) */
		if ((ret = parport_wait_event (port, msecs_to_jiffies(10))) < 0)
			return ret;

		status = parport_read_status (port);
		if ((status & mask) == result)
			return 0;

		if (!ret) {
			/* parport_wait_event didn't time out, but the
			 * peripheral wasn't actually ready either.
			 * Wait for another 10ms. */
			schedule_timeout_interruptible(msecs_to_jiffies(10));
		}
	}

	return 1;
}

#ifdef CONFIG_PARPORT_1284
/* Terminate a negotiated mode. */
static void parport_ieee1284_terminate (struct parport *port)
{
	int r;
	port = port->physport;

	/* EPP terminates differently. */
	switch (port->ieee1284.mode) {
	case IEEE1284_MODE_EPP:
	case IEEE1284_MODE_EPPSL:
	case IEEE1284_MODE_EPPSWE:
		/* Terminate from EPP mode. */

		/* Event 68: Set nInit low */
		parport_frob_control (port, PARPORT_CONTROL_INIT, 0);
		udelay (50);

		/* Event 69: Set nInit high, nSelectIn low */
		parport_frob_control (port,
				      PARPORT_CONTROL_SELECT
				      | PARPORT_CONTROL_INIT,
				      PARPORT_CONTROL_SELECT
				      | PARPORT_CONTROL_INIT);
		break;

	case IEEE1284_MODE_ECP:
	case IEEE1284_MODE_ECPRLE:
	case IEEE1284_MODE_ECPSWE:
		/* In ECP we can only terminate from fwd idle phase. */
		if (port->ieee1284.phase != IEEE1284_PH_FWD_IDLE) {
			/* Event 47: Set nInit high */
			parport_frob_control (port,
					      PARPORT_CONTROL_INIT
					      | PARPORT_CONTROL_AUTOFD,
					      PARPORT_CONTROL_INIT
					      | PARPORT_CONTROL_AUTOFD);

			/* Event 49: PError goes high */
			r = parport_wait_peripheral (port,
						     PARPORT_STATUS_PAPEROUT,
						     PARPORT_STATUS_PAPEROUT);
			if (r)
				DPRINTK (KERN_INFO "%s: Timeout at event 49\n",
					 port->name);

			parport_data_forward (port);
			DPRINTK (KERN_DEBUG "%s: ECP direction: forward\n",
				 port->name);
			port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
		}

		/* fall through */

	default:
		/* Terminate from all other modes. */

		/* Event 22: Set nSelectIn low, nAutoFd high */
		parport_frob_control (port,
				      PARPORT_CONTROL_SELECT
				      | PARPORT_CONTROL_AUTOFD,
				      PARPORT_CONTROL_SELECT);

		/* Event 24: nAck goes low */
		r = parport_wait_peripheral (port, PARPORT_STATUS_ACK, 0);
		if (r)
			DPRINTK (KERN_INFO "%s: Timeout at event 24\n",
				 port->name);

		/* Event 25: Set nAutoFd low */
		parport_frob_control (port,
				      PARPORT_CONTROL_AUTOFD,
				      PARPORT_CONTROL_AUTOFD);

		/* Event 27: nAck goes high */
		r = parport_wait_peripheral (port,
					     PARPORT_STATUS_ACK, 
					     PARPORT_STATUS_ACK);
		if (r)
			DPRINTK (KERN_INFO "%s: Timeout at event 27\n",
				 port->name);

		/* Event 29: Set nAutoFd high */
		parport_frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
	}

	port->ieee1284.mode = IEEE1284_MODE_COMPAT;
	port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;

	DPRINTK (KERN_DEBUG "%s: In compatibility (forward idle) mode\n",
		 port->name);
}		
#endif /* IEEE1284 support */

/**
 *	parport_negotiate - negotiate an IEEE 1284 mode
 *	@port: port to use
 *	@mode: mode to negotiate to
 *
 *	Use this to negotiate to a particular IEEE 1284 transfer mode.
 *	The @mode parameter should be one of the constants in
 *	parport.h starting %IEEE1284_MODE_xxx.
 *
 *	The return value is 0 if the peripheral has accepted the
 *	negotiation to the mode specified, -1 if the peripheral is not
 *	IEEE 1284 compliant (or not present), or 1 if the peripheral
 *	has rejected the negotiation.
 */

int parport_negotiate (struct parport *port, int mode)
{
#ifndef CONFIG_PARPORT_1284
	if (mode == IEEE1284_MODE_COMPAT)
		return 0;
	printk (KERN_ERR "parport: IEEE1284 not supported in this kernel\n");
	return -1;
#else
	int m = mode & ~IEEE1284_ADDR;
	int r;
	unsigned char xflag;

	port = port->physport;

	/* Is there anything to do? */
	if (port->ieee1284.mode == mode)
		return 0;

	/* Is the difference just an address-or-not bit? */
	if ((port->ieee1284.mode & ~IEEE1284_ADDR) == (mode & ~IEEE1284_ADDR)){
		port->ieee1284.mode = mode;
		return 0;
	}

	/* Go to compatibility forward idle mode */
	if (port->ieee1284.mode != IEEE1284_MODE_COMPAT)
		parport_ieee1284_terminate (port);

	if (mode == IEEE1284_MODE_COMPAT)
		/* Compatibility mode: no negotiation. */
		return 0; 

	switch (mode) {
	case IEEE1284_MODE_ECPSWE:
		m = IEEE1284_MODE_ECP;
		break;
	case IEEE1284_MODE_EPPSL:
	case IEEE1284_MODE_EPPSWE:
		m = IEEE1284_MODE_EPP;
		break;
	case IEEE1284_MODE_BECP:
		return -ENOSYS; /* FIXME (implement BECP) */
	}

	if (mode & IEEE1284_EXT_LINK)
		m = 1<<7; /* request extensibility link */

	port->ieee1284.phase = IEEE1284_PH_NEGOTIATION;

	/* Start off with nStrobe and nAutoFd high, and nSelectIn low */
	parport_frob_control (port,
			      PARPORT_CONTROL_STROBE
			      | PARPORT_CONTROL_AUTOFD
			      | PARPORT_CONTROL_SELECT,
			      PARPORT_CONTROL_SELECT);
	udelay(1);

	/* Event 0: Set data */
	parport_data_forward (port);
	parport_write_data (port, m);
	udelay (400); /* Shouldn't need to wait this long. */

	/* Event 1: Set nSelectIn high, nAutoFd low */
	parport_frob_control (port,
			      PARPORT_CONTROL_SELECT
			      | PARPORT_CONTROL_AUTOFD,
			      PARPORT_CONTROL_AUTOFD);

	/* Event 2: PError, Select, nFault go high, nAck goes low */
	if (parport_wait_peripheral (port,
				     PARPORT_STATUS_ERROR
				     | PARPORT_STATUS_SELECT
				     | PARPORT_STATUS_PAPEROUT
				     | PARPORT_STATUS_ACK,
				     PARPORT_STATUS_ERROR
				     | PARPORT_STATUS_SELECT
				     | PARPORT_STATUS_PAPEROUT)) {
		/* Timeout */
		parport_frob_control (port,
				      PARPORT_CONTROL_SELECT
				      | PARPORT_CONTROL_AUTOFD,
				      PARPORT_CONTROL_SELECT);
		DPRINTK (KERN_DEBUG
			 "%s: Peripheral not IEEE1284 compliant (0x%02X)\n",
			 port->name, parport_read_status (port));
		port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
		return -1; /* Not IEEE1284 compliant */
	}

	/* Event 3: Set nStrobe low */
	parport_frob_control (port,
			      PARPORT_CONTROL_STROBE,
			      PARPORT_CONTROL_STROBE);

	/* Event 4: Set nStrobe and nAutoFd high */
	udelay (5);
	parport_frob_control (port,
			      PARPORT_CONTROL_STROBE
			      | PARPORT_CONTROL_AUTOFD,
			      0);

	/* Event 6: nAck goes high */
	if (parport_wait_peripheral (port,
				     PARPORT_STATUS_ACK,
				     PARPORT_STATUS_ACK)) {
		/* This shouldn't really happen with a compliant device. */
		DPRINTK (KERN_DEBUG
			 "%s: Mode 0x%02x not supported? (0x%02x)\n",
			 port->name, mode, port->ops->read_status (port));
		parport_ieee1284_terminate (port);
		return 1;
	}

	xflag = parport_read_status (port) & PARPORT_STATUS_SELECT;

	/* xflag should be high for all modes other than nibble (0). */
	if (mode && !xflag) {
		/* Mode not supported. */
		DPRINTK (KERN_DEBUG "%s: Mode 0x%02x rejected by peripheral\n",
			 port->name, mode);
		parport_ieee1284_terminate (port);
		return 1;
	}

	/* More to do if we've requested extensibility link. */
	if (mode & IEEE1284_EXT_LINK) {
		m = mode & 0x7f;
		udelay (1);
		parport_write_data (port, m);
		udelay (1);

		/* Event 51: Set nStrobe low */
		parport_frob_control (port,
				      PARPORT_CONTROL_STROBE,
				      PARPORT_CONTROL_STROBE);

		/* Event 52: nAck goes low */
		if (parport_wait_peripheral (port, PARPORT_STATUS_ACK, 0)) {
			/* This peripheral is _very_ slow. */
			DPRINTK (KERN_DEBUG
				 "%s: Event 52 didn't happen\n",
				 port->name);
			parport_ieee1284_terminate (port);
			return 1;
		}

		/* Event 53: Set nStrobe high */
		parport_frob_control (port,
				      PARPORT_CONTROL_STROBE,
				      0);

		/* Event 55: nAck goes high */
		if (parport_wait_peripheral (port,
					     PARPORT_STATUS_ACK,
					     PARPORT_STATUS_ACK)) {
			/* This shouldn't really happen with a compliant
			 * device. */
			DPRINTK (KERN_DEBUG
				 "%s: Mode 0x%02x not supported? (0x%02x)\n",
				 port->name, mode,
				 port->ops->read_status (port));
			parport_ieee1284_terminate (port);
			return 1;
		}

		/* Event 54: Peripheral sets XFlag to reflect support */
		xflag = parport_read_status (port) & PARPORT_STATUS_SELECT;

		/* xflag should be high. */
		if (!xflag) {
			/* Extended mode not supported. */
			DPRINTK (KERN_DEBUG "%s: Extended mode 0x%02x not "
				 "supported\n", port->name, mode);
			parport_ieee1284_terminate (port);
			return 1;
		}

		/* Any further setup is left to the caller. */
	}

	/* Mode is supported */
	DPRINTK (KERN_DEBUG "%s: In mode 0x%02x\n", port->name, mode);
	port->ieee1284.mode = mode;

	/* But ECP is special */
	if (!(mode & IEEE1284_EXT_LINK) && (m & IEEE1284_MODE_ECP)) {
		port->ieee1284.phase = IEEE1284_PH_ECP_SETUP;

		/* Event 30: Set nAutoFd low */
		parport_frob_control (port,
				      PARPORT_CONTROL_AUTOFD,
				      PARPORT_CONTROL_AUTOFD);

		/* Event 31: PError goes high. */
		r = parport_wait_peripheral (port,
					     PARPORT_STATUS_PAPEROUT,
					     PARPORT_STATUS_PAPEROUT);
		if (r) {
			DPRINTK (KERN_INFO "%s: Timeout at event 31\n",
				port->name);
		}

		port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
		DPRINTK (KERN_DEBUG "%s: ECP direction: forward\n",
			 port->name);
	} else switch (mode) {
	case IEEE1284_MODE_NIBBLE:
	case IEEE1284_MODE_BYTE:
		port->ieee1284.phase = IEEE1284_PH_REV_IDLE;
		break;
	default:
		port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
	}


	return 0;
#endif /* IEEE1284 support */
}

/* Acknowledge that the peripheral has data available.
 * Events 18-20, in order to get from Reverse Idle phase
 * to Host Busy Data Available.
 * This will most likely be called from an interrupt.
 * Returns zero if data was available.
 */
#ifdef CONFIG_PARPORT_1284
static int parport_ieee1284_ack_data_avail (struct parport *port)
{
	if (parport_read_status (port) & PARPORT_STATUS_ERROR)
		/* Event 18 didn't happen. */
		return -1;

	/* Event 20: nAutoFd goes high. */
	port->ops->frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
	port->ieee1284.phase = IEEE1284_PH_HBUSY_DAVAIL;
	return 0;
}
#endif /* IEEE1284 support */

/* Handle an interrupt. */
void parport_ieee1284_interrupt (void *handle)
{
	struct parport *port = handle;
	parport_ieee1284_wakeup (port);

#ifdef CONFIG_PARPORT_1284
	if (port->ieee1284.phase == IEEE1284_PH_REV_IDLE) {
		/* An interrupt in this phase means that data
		 * is now available. */
		DPRINTK (KERN_DEBUG "%s: Data available\n", port->name);
		parport_ieee1284_ack_data_avail (port);
	}
#endif /* IEEE1284 support */
}

/**
 *	parport_write - write a block of data to a parallel port
 *	@port: port to write to
 *	@buffer: data buffer (in kernel space)
 *	@len: number of bytes of data to transfer
 *
 *	This will write up to @len bytes of @buffer to the port
 *	specified, using the IEEE 1284 transfer mode most recently
 *	negotiated to (using parport_negotiate()), as long as that
 *	mode supports forward transfers (host to peripheral).
 *
 *	It is the caller's responsibility to ensure that the first
 *	@len bytes of @buffer are valid.
 *
 *	This function returns the number of bytes transferred (if zero
 *	or positive), or else an error code.
 */

ssize_t parport_write (struct parport *port, const void *buffer, size_t len)
{
#ifndef CONFIG_PARPORT_1284
	return port->ops->compat_write_data (port, buffer, len, 0);
#else
	ssize_t retval;
	int mode = port->ieee1284.mode;
	int addr = mode & IEEE1284_ADDR;
	size_t (*fn) (struct parport *, const void *, size_t, int);

	/* Ignore the device-ID-request bit and the address bit. */
	mode &= ~(IEEE1284_DEVICEID | IEEE1284_ADDR);

	/* Use the mode we're in. */
	switch (mode) {
	case IEEE1284_MODE_NIBBLE:
	case IEEE1284_MODE_BYTE:
		parport_negotiate (port, IEEE1284_MODE_COMPAT);
		/* fall through */
	case IEEE1284_MODE_COMPAT:
		DPRINTK (KERN_DEBUG "%s: Using compatibility mode\n",
			 port->name);
		fn = port->ops->compat_write_data;
		break;

	case IEEE1284_MODE_EPP:
		DPRINTK (KERN_DEBUG "%s: Using EPP mode\n", port->name);
		if (addr) {
			fn = port->ops->epp_write_addr;
		} else {
			fn = port->ops->epp_write_data;
		}
		break;
	case IEEE1284_MODE_EPPSWE:
		DPRINTK (KERN_DEBUG "%s: Using software-emulated EPP mode\n",
			port->name);
		if (addr) {
			fn = parport_ieee1284_epp_write_addr;
		} else {
			fn = parport_ieee1284_epp_write_data;
		}
		break;
	case IEEE1284_MODE_ECP:
	case IEEE1284_MODE_ECPRLE:
		DPRINTK (KERN_DEBUG "%s: Using ECP mode\n", port->name);
		if (addr) {
			fn = port->ops->ecp_write_addr;
		} else {
			fn = port->ops->ecp_write_data;
		}
		break;

	case IEEE1284_MODE_ECPSWE:
		DPRINTK (KERN_DEBUG "%s: Using software-emulated ECP mode\n",
			 port->name);
		/* The caller has specified that it must be emulated,
		 * even if we have ECP hardware! */
		if (addr) {
			fn = parport_ieee1284_ecp_write_addr;
		} else {
			fn = parport_ieee1284_ecp_write_data;
		}
		break;

	default:
		DPRINTK (KERN_DEBUG "%s: Unknown mode 0x%02x\n", port->name,
			port->ieee1284.mode);
		return -ENOSYS;
	}

	retval = (*fn) (port, buffer, len, 0);
	DPRINTK (KERN_DEBUG "%s: wrote %d/%d bytes\n", port->name, retval, len);
	return retval;
#endif /* IEEE1284 support */
}

/**
 *	parport_read - read a block of data from a parallel port
 *	@port: port to read from
 *	@buffer: data buffer (in kernel space)
 *	@len: number of bytes of data to transfer
 *
 *	This will read up to @len bytes of @buffer to the port
 *	specified, using the IEEE 1284 transfer mode most recently
 *	negotiated to (using parport_negotiate()), as long as that
 *	mode supports reverse transfers (peripheral to host).
 *
 *	It is the caller's responsibility to ensure that the first
 *	@len bytes of @buffer are available to write to.
 *
 *	This function returns the number of bytes transferred (if zero
 *	or positive), or else an error code.
 */

ssize_t parport_read (struct parport *port, void *buffer, size_t len)
{
#ifndef CONFIG_PARPORT_1284
	printk (KERN_ERR "parport: IEEE1284 not supported in this kernel\n");
	return -ENODEV;
#else
	int mode = port->physport->ieee1284.mode;
	int addr = mode & IEEE1284_ADDR;
	size_t (*fn) (struct parport *, void *, size_t, int);

	/* Ignore the device-ID-request bit and the address bit. */
	mode &= ~(IEEE1284_DEVICEID | IEEE1284_ADDR);

	/* Use the mode we're in. */
	switch (mode) {
	case IEEE1284_MODE_COMPAT:
		/* if we can tri-state use BYTE mode instead of NIBBLE mode,
		 * if that fails, revert to NIBBLE mode -- ought to store somewhere
		 * the device's ability to do BYTE mode reverse transfers, so we don't
		 * end up needlessly calling negotiate(BYTE) repeately..  (fb)
		 */
		if ((port->physport->modes & PARPORT_MODE_TRISTATE) &&
		    !parport_negotiate (port, IEEE1284_MODE_BYTE)) {
			/* got into BYTE mode OK */
			DPRINTK (KERN_DEBUG "%s: Using byte mode\n", port->name);
			fn = port->ops->byte_read_data;
			break;
		}
		if (parport_negotiate (port, IEEE1284_MODE_NIBBLE)) {
			return -EIO;
		}
		/* fall through to NIBBLE */
	case IEEE1284_MODE_NIBBLE:
		DPRINTK (KERN_DEBUG "%s: Using nibble mode\n", port->name);
		fn = port->ops->nibble_read_data;
		break;

	case IEEE1284_MODE_BYTE:
		DPRINTK (KERN_DEBUG "%s: Using byte mode\n", port->name);
		fn = port->ops->byte_read_data;
		break;

	case IEEE1284_MODE_EPP:
		DPRINTK (KERN_DEBUG "%s: Using EPP mode\n", port->name);
		if (addr) {
			fn = port->ops->epp_read_addr;
		} else {
			fn = port->ops->epp_read_data;
		}
		break;
	case IEEE1284_MODE_EPPSWE:
		DPRINTK (KERN_DEBUG "%s: Using software-emulated EPP mode\n",
			port->name);
		if (addr) {
			fn = parport_ieee1284_epp_read_addr;
		} else {
			fn = parport_ieee1284_epp_read_data;
		}
		break;
	case IEEE1284_MODE_ECP:
	case IEEE1284_MODE_ECPRLE:
		DPRINTK (KERN_DEBUG "%s: Using ECP mode\n", port->name);
		fn = port->ops->ecp_read_data;
		break;

	case IEEE1284_MODE_ECPSWE:
		DPRINTK (KERN_DEBUG "%s: Using software-emulated ECP mode\n",
			 port->name);
		fn = parport_ieee1284_ecp_read_data;
		break;

	default:
		DPRINTK (KERN_DEBUG "%s: Unknown mode 0x%02x\n", port->name,
			 port->physport->ieee1284.mode);
		return -ENOSYS;
	}

	return (*fn) (port, buffer, len, 0);
#endif /* IEEE1284 support */
}

/**
 *	parport_set_timeout - set the inactivity timeout for a device
 *	@dev: device on a port
 *	@inactivity: inactivity timeout (in jiffies)
 *
 *	This sets the inactivity timeout for a particular device on a
 *	port.  This affects functions like parport_wait_peripheral().
 *	The special value 0 means not to call schedule() while dealing
 *	with this device.
 *
 *	The return value is the previous inactivity timeout.
 *
 *	Any callers of parport_wait_event() for this device are woken
 *	up.
 */

long parport_set_timeout (struct pardevice *dev, long inactivity)
{
	long int old = dev->timeout;

	dev->timeout = inactivity;

	if (dev->port->physport->cad == dev)
		parport_ieee1284_wakeup (dev->port);

	return old;
}

/* Exported symbols for modules. */

EXPORT_SYMBOL(parport_negotiate);
EXPORT_SYMBOL(parport_write);
EXPORT_SYMBOL(parport_read);
EXPORT_SYMBOL(parport_wait_peripheral);
EXPORT_SYMBOL(parport_wait_event);
EXPORT_SYMBOL(parport_set_timeout);
EXPORT_SYMBOL(parport_ieee1284_interrupt);