summaryrefslogtreecommitdiff
path: root/drivers/macintosh/via-cuda.c
blob: f8dd1e8315306fbd5ddcf2387b0f57976b29f04d (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Device driver for the Cuda and Egret system controllers found on PowerMacs
 * and 68k Macs.
 *
 * The Cuda or Egret is a 6805 microcontroller interfaced to the 6522 VIA.
 * This MCU controls system power, Parameter RAM, Real Time Clock and the
 * Apple Desktop Bus (ADB) that connects to the keyboard and mouse.
 *
 * Copyright (C) 1996 Paul Mackerras.
 */
#include <linux/stdarg.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/adb.h>
#include <linux/cuda.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

#ifdef CONFIG_PPC
#include <asm/machdep.h>
#include <asm/pmac_feature.h>
#else
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_via.h>
#endif
#include <asm/io.h>
#include <linux/init.h>

static volatile unsigned char __iomem *via;
static DEFINE_SPINLOCK(cuda_lock);

/* VIA registers - spaced 0x200 bytes apart */
#define RS		0x200		/* skip between registers */
#define B		0		/* B-side data */
#define A		RS		/* A-side data */
#define DIRB		(2*RS)		/* B-side direction (1=output) */
#define DIRA		(3*RS)		/* A-side direction (1=output) */
#define T1CL		(4*RS)		/* Timer 1 ctr/latch (low 8 bits) */
#define T1CH		(5*RS)		/* Timer 1 counter (high 8 bits) */
#define T1LL		(6*RS)		/* Timer 1 latch (low 8 bits) */
#define T1LH		(7*RS)		/* Timer 1 latch (high 8 bits) */
#define T2CL		(8*RS)		/* Timer 2 ctr/latch (low 8 bits) */
#define T2CH		(9*RS)		/* Timer 2 counter (high 8 bits) */
#define SR		(10*RS)		/* Shift register */
#define ACR		(11*RS)		/* Auxiliary control register */
#define PCR		(12*RS)		/* Peripheral control register */
#define IFR		(13*RS)		/* Interrupt flag register */
#define IER		(14*RS)		/* Interrupt enable register */
#define ANH		(15*RS)		/* A-side data, no handshake */

/*
 * When the Cuda design replaced the Egret, some signal names and
 * logic sense changed. They all serve the same purposes, however.
 *
 *   VIA pin       |  Egret pin
 * ----------------+------------------------------------------
 *   PB3 (input)   |  Transceiver session   (active low)
 *   PB4 (output)  |  VIA full              (active high)
 *   PB5 (output)  |  System session        (active high)
 *
 *   VIA pin       |  Cuda pin
 * ----------------+------------------------------------------
 *   PB3 (input)   |  Transfer request      (active low)
 *   PB4 (output)  |  Byte acknowledge      (active low)
 *   PB5 (output)  |  Transfer in progress  (active low)
 */

/* Bits in Port B data register */
#define TREQ		0x08		/* Transfer request */
#define TACK		0x10		/* Transfer acknowledge */
#define TIP		0x20		/* Transfer in progress */

/* Bits in ACR */
#define SR_CTRL		0x1c		/* Shift register control bits */
#define SR_EXT		0x0c		/* Shift on external clock */
#define SR_OUT		0x10		/* Shift out if 1 */

/* Bits in IFR and IER */
#define IER_SET		0x80		/* set bits in IER */
#define IER_CLR		0		/* clear bits in IER */
#define SR_INT		0x04		/* Shift register full/empty */

/* Duration of byte acknowledgement pulse (us) */
#define EGRET_TACK_ASSERTED_DELAY	300
#define EGRET_TACK_NEGATED_DELAY	400

/* Interval from interrupt to start of session (us) */
#define EGRET_SESSION_DELAY		450

#ifdef CONFIG_PPC
#define mcu_is_egret	false
#else
static bool mcu_is_egret;
#endif

static inline bool TREQ_asserted(u8 portb)
{
	return !(portb & TREQ);
}

static inline void assert_TIP(void)
{
	if (mcu_is_egret) {
		udelay(EGRET_SESSION_DELAY);
		out_8(&via[B], in_8(&via[B]) | TIP);
	} else
		out_8(&via[B], in_8(&via[B]) & ~TIP);
}

static inline void assert_TIP_and_TACK(void)
{
	if (mcu_is_egret) {
		udelay(EGRET_SESSION_DELAY);
		out_8(&via[B], in_8(&via[B]) | TIP | TACK);
	} else
		out_8(&via[B], in_8(&via[B]) & ~(TIP | TACK));
}

static inline void assert_TACK(void)
{
	if (mcu_is_egret) {
		udelay(EGRET_TACK_NEGATED_DELAY);
		out_8(&via[B], in_8(&via[B]) | TACK);
	} else
		out_8(&via[B], in_8(&via[B]) & ~TACK);
}

static inline void toggle_TACK(void)
{
	out_8(&via[B], in_8(&via[B]) ^ TACK);
}

static inline void negate_TACK(void)
{
	if (mcu_is_egret) {
		udelay(EGRET_TACK_ASSERTED_DELAY);
		out_8(&via[B], in_8(&via[B]) & ~TACK);
	} else
		out_8(&via[B], in_8(&via[B]) | TACK);
}

static inline void negate_TIP_and_TACK(void)
{
	if (mcu_is_egret) {
		udelay(EGRET_TACK_ASSERTED_DELAY);
		out_8(&via[B], in_8(&via[B]) & ~(TIP | TACK));
	} else
		out_8(&via[B], in_8(&via[B]) | TIP | TACK);
}

static enum cuda_state {
    idle,
    sent_first_byte,
    sending,
    reading,
    read_done,
    awaiting_reply
} cuda_state;

static struct adb_request *current_req;
static struct adb_request *last_req;
static unsigned char cuda_rbuf[16];
static unsigned char *reply_ptr;
static int reading_reply;
static int data_index;
static int cuda_irq;
#ifdef CONFIG_PPC
static struct device_node *vias;
#endif
static int cuda_fully_inited;

#ifdef CONFIG_ADB
static int cuda_probe(void);
static int cuda_send_request(struct adb_request *req, int sync);
static int cuda_adb_autopoll(int devs);
static int cuda_reset_adb_bus(void);
#endif /* CONFIG_ADB */

static int cuda_init_via(void);
static void cuda_start(void);
static irqreturn_t cuda_interrupt(int irq, void *arg);
static void cuda_input(unsigned char *buf, int nb);
void cuda_poll(void);
static int cuda_write(struct adb_request *req);

int cuda_request(struct adb_request *req,
		 void (*done)(struct adb_request *), int nbytes, ...);

#ifdef CONFIG_ADB
struct adb_driver via_cuda_driver = {
	.name         = "CUDA",
	.probe        = cuda_probe,
	.send_request = cuda_send_request,
	.autopoll     = cuda_adb_autopoll,
	.poll         = cuda_poll,
	.reset_bus    = cuda_reset_adb_bus,
};
#endif /* CONFIG_ADB */

#ifdef CONFIG_MAC
int __init find_via_cuda(void)
{
    struct adb_request req;
    int err;

    if (macintosh_config->adb_type != MAC_ADB_CUDA &&
        macintosh_config->adb_type != MAC_ADB_EGRET)
	return 0;

    via = via1;
    cuda_state = idle;
    mcu_is_egret = macintosh_config->adb_type == MAC_ADB_EGRET;

    err = cuda_init_via();
    if (err) {
	printk(KERN_ERR "cuda_init_via() failed\n");
	via = NULL;
	return 0;
    }

    /* enable autopoll */
    cuda_request(&req, NULL, 3, CUDA_PACKET, CUDA_AUTOPOLL, 1);
    while (!req.complete)
	cuda_poll();

    return 1;
}
#else
int __init find_via_cuda(void)
{
    struct adb_request req;
    struct resource res;
    int err;

    if (vias)
	return 1;
    vias = of_find_node_by_name(NULL, "via-cuda");
    if (!vias)
	return 0;

    err = of_address_to_resource(vias, 0, &res);
    if (err) {
	    printk(KERN_ERR "via-cuda: Error getting \"reg\" property !\n");
	    goto fail;
    }
    via = ioremap(res.start, 0x2000);
    if (via == NULL) {
	    printk(KERN_ERR "via-cuda: Can't map address !\n");
	    goto fail;
    }

    cuda_state = idle;
    sys_ctrler = SYS_CTRLER_CUDA;

    err = cuda_init_via();
    if (err) {
	printk(KERN_ERR "cuda_init_via() failed\n");
	via = NULL;
	return 0;
    }

    /* Clear and enable interrupts, but only on PPC. On 68K it's done  */
    /* for us by the main VIA driver in arch/m68k/mac/via.c        */

    out_8(&via[IFR], 0x7f);	/* clear interrupts by writing 1s */
    out_8(&via[IER], IER_SET|SR_INT); /* enable interrupt from SR */

    /* enable autopoll */
    cuda_request(&req, NULL, 3, CUDA_PACKET, CUDA_AUTOPOLL, 1);
    while (!req.complete)
	cuda_poll();

    return 1;

 fail:
    of_node_put(vias);
    vias = NULL;
    return 0;
}
#endif /* !defined CONFIG_MAC */

static int __init via_cuda_start(void)
{
    if (via == NULL)
	return -ENODEV;

#ifdef CONFIG_MAC
    cuda_irq = IRQ_MAC_ADB;
#else
    cuda_irq = irq_of_parse_and_map(vias, 0);
    if (!cuda_irq) {
	printk(KERN_ERR "via-cuda: can't map interrupts for %pOF\n",
	       vias);
	return -ENODEV;
    }
#endif

    if (request_irq(cuda_irq, cuda_interrupt, 0, "ADB", cuda_interrupt)) {
	printk(KERN_ERR "via-cuda: can't request irq %d\n", cuda_irq);
	return -EAGAIN;
    }

    pr_info("Macintosh Cuda and Egret driver.\n");

    cuda_fully_inited = 1;
    return 0;
}

device_initcall(via_cuda_start);

#ifdef CONFIG_ADB
static int
cuda_probe(void)
{
#ifdef CONFIG_PPC
    if (sys_ctrler != SYS_CTRLER_CUDA)
	return -ENODEV;
#else
    if (macintosh_config->adb_type != MAC_ADB_CUDA &&
        macintosh_config->adb_type != MAC_ADB_EGRET)
	return -ENODEV;
#endif
    if (via == NULL)
	return -ENODEV;
    return 0;
}
#endif /* CONFIG_ADB */

static int __init sync_egret(void)
{
	if (TREQ_asserted(in_8(&via[B]))) {
		/* Complete the inbound transfer */
		assert_TIP_and_TACK();
		while (1) {
			negate_TACK();
			mdelay(1);
			(void)in_8(&via[SR]);
			assert_TACK();
			if (!TREQ_asserted(in_8(&via[B])))
				break;
		}
		negate_TIP_and_TACK();
	} else if (in_8(&via[B]) & TIP) {
		/* Terminate the outbound transfer */
		negate_TACK();
		assert_TACK();
		mdelay(1);
		negate_TIP_and_TACK();
	}
	/* Clear shift register interrupt */
	if (in_8(&via[IFR]) & SR_INT)
		(void)in_8(&via[SR]);
	return 0;
}

#define WAIT_FOR(cond, what)					\
    do {                                                        \
    	int x;							\
	for (x = 1000; !(cond); --x) {				\
	    if (x == 0) {					\
		pr_err("Timeout waiting for " what "\n");	\
		return -ENXIO;					\
	    }							\
	    udelay(100);					\
	}							\
    } while (0)

static int
__init cuda_init_via(void)
{
#ifdef CONFIG_PPC
    out_8(&via[IER], 0x7f);					/* disable interrupts from VIA */
    (void)in_8(&via[IER]);
#else
    out_8(&via[IER], SR_INT);					/* disable SR interrupt from VIA */
#endif

    out_8(&via[DIRB], (in_8(&via[DIRB]) | TACK | TIP) & ~TREQ);	/* TACK & TIP out */
    out_8(&via[ACR], (in_8(&via[ACR]) & ~SR_CTRL) | SR_EXT);	/* SR data in */
    (void)in_8(&via[SR]);					/* clear any left-over data */

    if (mcu_is_egret)
	return sync_egret();

    negate_TIP_and_TACK();

    /* delay 4ms and then clear any pending interrupt */
    mdelay(4);
    (void)in_8(&via[SR]);
    out_8(&via[IFR], SR_INT);

    /* sync with the CUDA - assert TACK without TIP */
    assert_TACK();

    /* wait for the CUDA to assert TREQ in response */
    WAIT_FOR(TREQ_asserted(in_8(&via[B])), "CUDA response to sync");

    /* wait for the interrupt and then clear it */
    WAIT_FOR(in_8(&via[IFR]) & SR_INT, "CUDA response to sync (2)");
    (void)in_8(&via[SR]);
    out_8(&via[IFR], SR_INT);

    /* finish the sync by negating TACK */
    negate_TACK();

    /* wait for the CUDA to negate TREQ and the corresponding interrupt */
    WAIT_FOR(!TREQ_asserted(in_8(&via[B])), "CUDA response to sync (3)");
    WAIT_FOR(in_8(&via[IFR]) & SR_INT, "CUDA response to sync (4)");
    (void)in_8(&via[SR]);
    out_8(&via[IFR], SR_INT);

    return 0;
}

#ifdef CONFIG_ADB
/* Send an ADB command */
static int
cuda_send_request(struct adb_request *req, int sync)
{
    int i;

    if ((via == NULL) || !cuda_fully_inited) {
	req->complete = 1;
	return -ENXIO;
    }
  
    req->reply_expected = 1;

    i = cuda_write(req);
    if (i)
	return i;

    if (sync) {
	while (!req->complete)
	    cuda_poll();
    }
    return 0;
}


/* Enable/disable autopolling */
static int
cuda_adb_autopoll(int devs)
{
    struct adb_request req;

    if ((via == NULL) || !cuda_fully_inited)
	return -ENXIO;

    cuda_request(&req, NULL, 3, CUDA_PACKET, CUDA_AUTOPOLL, (devs? 1: 0));
    while (!req.complete)
	cuda_poll();
    return 0;
}

/* Reset adb bus - how do we do this?? */
static int
cuda_reset_adb_bus(void)
{
    struct adb_request req;

    if ((via == NULL) || !cuda_fully_inited)
	return -ENXIO;

    cuda_request(&req, NULL, 2, ADB_PACKET, 0);		/* maybe? */
    while (!req.complete)
	cuda_poll();
    return 0;
}
#endif /* CONFIG_ADB */

/* Construct and send a cuda request */
int
cuda_request(struct adb_request *req, void (*done)(struct adb_request *),
	     int nbytes, ...)
{
    va_list list;
    int i;

    if (via == NULL) {
	req->complete = 1;
	return -ENXIO;
    }

    req->nbytes = nbytes;
    req->done = done;
    va_start(list, nbytes);
    for (i = 0; i < nbytes; ++i)
	req->data[i] = va_arg(list, int);
    va_end(list);
    req->reply_expected = 1;
    return cuda_write(req);
}
EXPORT_SYMBOL(cuda_request);

static int
cuda_write(struct adb_request *req)
{
    unsigned long flags;

    if (req->nbytes < 2 || req->data[0] > CUDA_PACKET) {
	req->complete = 1;
	return -EINVAL;
    }
    req->next = NULL;
    req->sent = 0;
    req->complete = 0;
    req->reply_len = 0;

    spin_lock_irqsave(&cuda_lock, flags);
    if (current_req) {
	last_req->next = req;
	last_req = req;
    } else {
	current_req = req;
	last_req = req;
	if (cuda_state == idle)
	    cuda_start();
    }
    spin_unlock_irqrestore(&cuda_lock, flags);

    return 0;
}

static void
cuda_start(void)
{
    /* assert cuda_state == idle */
    if (current_req == NULL)
	return;
    data_index = 0;
    if (TREQ_asserted(in_8(&via[B])))
	return;			/* a byte is coming in from the CUDA */

    /* set the shift register to shift out and send a byte */
    out_8(&via[ACR], in_8(&via[ACR]) | SR_OUT);
    out_8(&via[SR], current_req->data[data_index++]);
    if (mcu_is_egret)
	assert_TIP_and_TACK();
    else
	assert_TIP();
    cuda_state = sent_first_byte;
}

void
cuda_poll(void)
{
	cuda_interrupt(0, NULL);
}
EXPORT_SYMBOL(cuda_poll);

#define ARRAY_FULL(a, p)	((p) - (a) == ARRAY_SIZE(a))

static irqreturn_t
cuda_interrupt(int irq, void *arg)
{
    unsigned long flags;
    u8 status;
    struct adb_request *req = NULL;
    unsigned char ibuf[16];
    int ibuf_len = 0;
    int complete = 0;
    bool full;
    
    spin_lock_irqsave(&cuda_lock, flags);

    /* On powermacs, this handler is registered for the VIA IRQ. But they use
     * just the shift register IRQ -- other VIA interrupt sources are disabled.
     * On m68k macs, the VIA IRQ sources are dispatched individually. Unless
     * we are polling, the shift register IRQ flag has already been cleared.
     */

#ifdef CONFIG_MAC
    if (!arg)
#endif
    {
        if ((in_8(&via[IFR]) & SR_INT) == 0) {
            spin_unlock_irqrestore(&cuda_lock, flags);
            return IRQ_NONE;
        } else {
            out_8(&via[IFR], SR_INT);
        }
    }

    status = in_8(&via[B]) & (TIP | TACK | TREQ);

    switch (cuda_state) {
    case idle:
	/* System controller has unsolicited data for us */
	(void)in_8(&via[SR]);
idle_state:
	assert_TIP();
	cuda_state = reading;
	reply_ptr = cuda_rbuf;
	reading_reply = 0;
	break;

    case awaiting_reply:
	/* System controller has reply data for us */
	(void)in_8(&via[SR]);
	assert_TIP();
	cuda_state = reading;
	reply_ptr = current_req->reply;
	reading_reply = 1;
	break;

    case sent_first_byte:
	if (TREQ_asserted(status)) {
	    /* collision */
	    out_8(&via[ACR], in_8(&via[ACR]) & ~SR_OUT);
	    (void)in_8(&via[SR]);
	    negate_TIP_and_TACK();
	    cuda_state = idle;
	    /* Egret does not raise an "aborted" interrupt */
	    if (mcu_is_egret)
		goto idle_state;
	} else {
	    out_8(&via[SR], current_req->data[data_index++]);
	    toggle_TACK();
	    if (mcu_is_egret)
		assert_TACK();
	    cuda_state = sending;
	}
	break;

    case sending:
	req = current_req;
	if (data_index >= req->nbytes) {
	    out_8(&via[ACR], in_8(&via[ACR]) & ~SR_OUT);
	    (void)in_8(&via[SR]);
	    negate_TIP_and_TACK();
	    req->sent = 1;
	    if (req->reply_expected) {
		cuda_state = awaiting_reply;
	    } else {
		current_req = req->next;
		complete = 1;
		/* not sure about this */
		cuda_state = idle;
		cuda_start();
	    }
	} else {
	    out_8(&via[SR], req->data[data_index++]);
	    toggle_TACK();
	    if (mcu_is_egret)
		assert_TACK();
	}
	break;

    case reading:
	full = reading_reply ? ARRAY_FULL(current_req->reply, reply_ptr)
	                     : ARRAY_FULL(cuda_rbuf, reply_ptr);
	if (full)
	    (void)in_8(&via[SR]);
	else
	    *reply_ptr++ = in_8(&via[SR]);
	if (!TREQ_asserted(status) || full) {
	    if (mcu_is_egret)
		assert_TACK();
	    /* that's all folks */
	    negate_TIP_and_TACK();
	    cuda_state = read_done;
	    /* Egret does not raise a "read done" interrupt */
	    if (mcu_is_egret)
		goto read_done_state;
	} else {
	    toggle_TACK();
	    if (mcu_is_egret)
		negate_TACK();
	}
	break;

    case read_done:
	(void)in_8(&via[SR]);
read_done_state:
	if (reading_reply) {
	    req = current_req;
	    req->reply_len = reply_ptr - req->reply;
	    if (req->data[0] == ADB_PACKET) {
		/* Have to adjust the reply from ADB commands */
		if (req->reply_len <= 2 || (req->reply[1] & 2) != 0) {
		    /* the 0x2 bit indicates no response */
		    req->reply_len = 0;
		} else {
		    /* leave just the command and result bytes in the reply */
		    req->reply_len -= 2;
		    memmove(req->reply, req->reply + 2, req->reply_len);
		}
	    }
	    current_req = req->next;
	    complete = 1;
	    reading_reply = 0;
	} else {
	    /* This is tricky. We must break the spinlock to call
	     * cuda_input. However, doing so means we might get
	     * re-entered from another CPU getting an interrupt
	     * or calling cuda_poll(). I ended up using the stack
	     * (it's only for 16 bytes) and moving the actual
	     * call to cuda_input to outside of the lock.
	     */
	    ibuf_len = reply_ptr - cuda_rbuf;
	    memcpy(ibuf, cuda_rbuf, ibuf_len);
	}
	reply_ptr = cuda_rbuf;
	cuda_state = idle;
	cuda_start();
	if (cuda_state == idle && TREQ_asserted(in_8(&via[B]))) {
	    assert_TIP();
	    cuda_state = reading;
	}
	break;

    default:
	pr_err("cuda_interrupt: unknown cuda_state %d?\n", cuda_state);
    }
    spin_unlock_irqrestore(&cuda_lock, flags);
    if (complete && req) {
    	void (*done)(struct adb_request *) = req->done;
    	mb();
    	req->complete = 1;
    	/* Here, we assume that if the request has a done member, the
    	 * struct request will survive to setting req->complete to 1
    	 */
    	if (done)
		(*done)(req);
    }
    if (ibuf_len)
	cuda_input(ibuf, ibuf_len);
    return IRQ_HANDLED;
}

static void
cuda_input(unsigned char *buf, int nb)
{
    switch (buf[0]) {
    case ADB_PACKET:
#ifdef CONFIG_XMON
	if (nb == 5 && buf[2] == 0x2c) {
	    extern int xmon_wants_key, xmon_adb_keycode;
	    if (xmon_wants_key) {
		xmon_adb_keycode = buf[3];
		return;
	    }
	}
#endif /* CONFIG_XMON */
#ifdef CONFIG_ADB
	adb_input(buf+2, nb-2, buf[1] & 0x40);
#endif /* CONFIG_ADB */
	break;

    case TIMER_PACKET:
	/* Egret sends these periodically. Might be useful as a 'heartbeat'
	 * to trigger a recovery for the VIA shift register errata.
	 */
	break;

    default:
	print_hex_dump(KERN_INFO, "cuda_input: ", DUMP_PREFIX_NONE, 32, 1,
	               buf, nb, false);
    }
}

/* Offset between Unix time (1970-based) and Mac time (1904-based) */
#define RTC_OFFSET	2082844800

time64_t cuda_get_time(void)
{
	struct adb_request req;
	u32 now;

	if (cuda_request(&req, NULL, 2, CUDA_PACKET, CUDA_GET_TIME) < 0)
		return 0;
	while (!req.complete)
		cuda_poll();
	if (req.reply_len != 7)
		pr_err("%s: got %d byte reply\n", __func__, req.reply_len);
	now = (req.reply[3] << 24) + (req.reply[4] << 16) +
	      (req.reply[5] << 8) + req.reply[6];
	return (time64_t)now - RTC_OFFSET;
}

int cuda_set_rtc_time(struct rtc_time *tm)
{
	u32 now;
	struct adb_request req;

	now = lower_32_bits(rtc_tm_to_time64(tm) + RTC_OFFSET);
	if (cuda_request(&req, NULL, 6, CUDA_PACKET, CUDA_SET_TIME,
	                 now >> 24, now >> 16, now >> 8, now) < 0)
		return -ENXIO;
	while (!req.complete)
		cuda_poll();
	if ((req.reply_len != 3) && (req.reply_len != 7))
		pr_err("%s: got %d byte reply\n", __func__, req.reply_len);
	return 0;
}