summaryrefslogtreecommitdiff
path: root/drivers/macintosh/via-macii.c
blob: c9570fcf1cce10fdf06a607aba75d31331011668 (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
/*
 * Device driver for the via ADB on (many) Mac II-class machines
 *
 * Based on the original ADB keyboard handler Copyright (c) 1997 Alan Cox
 * Also derived from code Copyright (C) 1996 Paul Mackerras.
 *
 * With various updates provided over the years by Michael Schmitz,
 * Guideo Koerber and others.
 *
 * Rewrite for Unified ADB by Joshua M. Thompson (funaho@jurai.org)
 *
 * 1999-08-02 (jmt) - Initial rewrite for Unified ADB.
 * 2000-03-29 Tony Mantler <tonym@mac.linux-m68k.org>
 * 				- Big overhaul, should actually work now.
 * 2006-12-31 Finn Thain <fthain@telegraphics.com.au> - Another overhaul.
 *
 * Suggested reading:
 *   Inside Macintosh, ch. 5 ADB Manager
 *   Guide to the Macinstosh Family Hardware, ch. 8 Apple Desktop Bus
 *   Rockwell R6522 VIA datasheet
 *
 * Apple's "ADB Analyzer" bus sniffer is invaluable:
 *   ftp://ftp.apple.com/developer/Tool_Chest/Devices_-_Hardware/Apple_Desktop_Bus/
 */
 
#include <stdarg.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/adb.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_via.h>
#include <asm/system.h>

static volatile unsigned char *via;

/* 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 */

/* Bits in B data register: all active low */
#define CTLR_IRQ	0x08		/* Controller rcv status (input) */
#define ST_MASK		0x30		/* mask for selecting ADB state bits */

/* 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 */

/* ADB transaction states according to GMHW */
#define ST_CMD		0x00		/* ADB state: command byte */
#define ST_EVEN		0x10		/* ADB state: even data byte */
#define ST_ODD		0x20		/* ADB state: odd data byte */
#define ST_IDLE		0x30		/* ADB state: idle, nothing to send */

static int  macii_init_via(void);
static void macii_start(void);
static irqreturn_t macii_interrupt(int irq, void *arg);
static void macii_queue_poll(void);

static int macii_probe(void);
static int macii_init(void);
static int macii_send_request(struct adb_request *req, int sync);
static int macii_write(struct adb_request *req);
static int macii_autopoll(int devs);
static void macii_poll(void);
static int macii_reset_bus(void);

struct adb_driver via_macii_driver = {
	"Mac II",
	macii_probe,
	macii_init,
	macii_send_request,
	macii_autopoll,
	macii_poll,
	macii_reset_bus
};

static enum macii_state {
	idle,
	sending,
	reading,
	read_done,
} macii_state;

static struct adb_request *current_req; /* first request struct in the queue */
static struct adb_request *last_req;     /* last request struct in the queue */
static unsigned char reply_buf[16];        /* storage for autopolled replies */
static unsigned char *reply_ptr;     /* next byte in reply_buf or req->reply */
static int reading_reply;        /* store reply in reply_buf else req->reply */
static int data_index;      /* index of the next byte to send from req->data */
static int reply_len; /* number of bytes received in reply_buf or req->reply */
static int status;          /* VIA's ADB status bits captured upon interrupt */
static int last_status;              /* status bits as at previous interrupt */
static int srq_asserted;     /* have to poll for the device that asserted it */
static int command_byte;         /* the most recent command byte transmitted */
static int autopoll_devs;      /* bits set are device addresses to be polled */

/* Sanity check for request queue. Doesn't check for cycles. */
static int request_is_queued(struct adb_request *req) {
	struct adb_request *cur;
	unsigned long flags;
	local_irq_save(flags);
	cur = current_req;
	while (cur) {
		if (cur == req) {
			local_irq_restore(flags);
			return 1;
		}
		cur = cur->next;
	}
	local_irq_restore(flags);
	return 0;
}

/* Check for MacII style ADB */
static int macii_probe(void)
{
	if (macintosh_config->adb_type != MAC_ADB_II) return -ENODEV;

	via = via1;

	printk("adb: Mac II ADB Driver v1.0 for Unified ADB\n");
	return 0;
}

/* Initialize the driver */
int macii_init(void)
{
	unsigned long flags;
	int err;
	
	local_irq_save(flags);
	
	err = macii_init_via();
	if (err) goto out;

	err = request_irq(IRQ_MAC_ADB, macii_interrupt, 0, "ADB",
			  macii_interrupt);
	if (err) goto out;

	macii_state = idle;
out:
	local_irq_restore(flags);
	return err;
}

/* initialize the hardware */	
static int macii_init_via(void)
{
	unsigned char x;

	/* We want CTLR_IRQ as input and ST_EVEN | ST_ODD as output lines. */
	via[DIRB] = (via[DIRB] | ST_EVEN | ST_ODD) & ~CTLR_IRQ;

	/* Set up state: idle */
	via[B] |= ST_IDLE;
	last_status = via[B] & (ST_MASK|CTLR_IRQ);

	/* Shift register on input */
	via[ACR] = (via[ACR] & ~SR_CTRL) | SR_EXT;

	/* Wipe any pending data and int */
	x = via[SR];

	return 0;
}

/* Send an ADB poll (Talk Register 0 command prepended to the request queue) */
static void macii_queue_poll(void)
{
	/* No point polling the active device as it will never assert SRQ, so
	 * poll the next device in the autopoll list. This could leave us
	 * stuck in a polling loop if an unprobed device is asserting SRQ.
	 * In theory, that could only happen if a device was plugged in after
	 * probing started. Unplugging it again will break the cycle.
	 * (Simply polling the next higher device often ends up polling almost
	 * every device (after wrapping around), which takes too long.)
	 */
	int device_mask;
	int next_device;
	static struct adb_request req;

	if (!autopoll_devs) return;

	device_mask = (1 << (((command_byte & 0xF0) >> 4) + 1)) - 1;
	if (autopoll_devs & ~device_mask)
		next_device = ffs(autopoll_devs & ~device_mask) - 1;
	else
		next_device = ffs(autopoll_devs) - 1;

	BUG_ON(request_is_queued(&req));

	adb_request(&req, NULL, ADBREQ_NOSEND, 1,
	            ADB_READREG(next_device, 0));

	req.sent = 0;
	req.complete = 0;
	req.reply_len = 0;
	req.next = current_req;

	if (current_req != NULL) {
		current_req = &req;
	} else {
		current_req = &req;
		last_req = &req;
	}
}

/* Send an ADB request; if sync, poll out the reply 'till it's done */
static int macii_send_request(struct adb_request *req, int sync)
{
	int err;
	unsigned long flags;

	BUG_ON(request_is_queued(req));

	local_irq_save(flags);
	err = macii_write(req);
	local_irq_restore(flags);

	if (!err && sync) {
		while (!req->complete) {
			macii_poll();
		}
		BUG_ON(request_is_queued(req));
	}

	return err;
}

/* Send an ADB request (append to request queue) */
static int macii_write(struct adb_request *req)
{
	if (req->nbytes < 2 || req->data[0] != ADB_PACKET || req->nbytes > 15) {
		req->complete = 1;
		return -EINVAL;
	}
	
	req->next = NULL;
	req->sent = 0;
	req->complete = 0;
	req->reply_len = 0;

	if (current_req != NULL) {
		last_req->next = req;
		last_req = req;
	} else {
		current_req = req;
		last_req = req;
		if (macii_state == idle) macii_start();
	}
	return 0;
}

/* Start auto-polling */
static int macii_autopoll(int devs)
{
	static struct adb_request req;
	unsigned long flags;
	int err = 0;

	/* bit 1 == device 1, and so on. */
	autopoll_devs = devs & 0xFFFE;

	if (!autopoll_devs) return 0;

	local_irq_save(flags);

	if (current_req == NULL) {
		/* Send a Talk Reg 0. The controller will repeatedly transmit
		 * this as long as it is idle.
		 */
		adb_request(&req, NULL, ADBREQ_NOSEND, 1,
		            ADB_READREG(ffs(autopoll_devs) - 1, 0));
		err = macii_write(&req);
	}

	local_irq_restore(flags);
	return err;
}

static inline int need_autopoll(void) {
	/* Was the last command Talk Reg 0
	 * and is the target on the autopoll list?
	 */
	if ((command_byte & 0x0F) == 0x0C &&
	    ((1 << ((command_byte & 0xF0) >> 4)) & autopoll_devs))
		return 0;
	return 1;
}

/* Prod the chip without interrupts */
static void macii_poll(void)
{
	disable_irq(IRQ_MAC_ADB);
	macii_interrupt(0, NULL);
	enable_irq(IRQ_MAC_ADB);
}

/* Reset the bus */
static int macii_reset_bus(void)
{
	static struct adb_request req;
	
	if (request_is_queued(&req))
		return 0;

	/* Command = 0, Address = ignored */
	adb_request(&req, NULL, 0, 1, ADB_BUSRESET);

	/* Don't want any more requests during the Global Reset low time. */
	udelay(3000);

	return 0;
}

/* Start sending ADB packet */
static void macii_start(void)
{
	struct adb_request *req;

	req = current_req;

	BUG_ON(req == NULL);

	BUG_ON(macii_state != idle);

	/* Now send it. Be careful though, that first byte of the request
	 * is actually ADB_PACKET; the real data begins at index 1!
	 * And req->nbytes is the number of bytes of real data plus one.
	 */

	/* store command byte */
	command_byte = req->data[1];
	/* Output mode */
	via[ACR] |= SR_OUT;
	/* Load data */
	via[SR] = req->data[1];
	/* set ADB state to 'command' */
	via[B] = (via[B] & ~ST_MASK) | ST_CMD;

	macii_state = sending;
	data_index = 2;
}

/*
 * The notorious ADB interrupt handler - does all of the protocol handling.
 * Relies on the ADB controller sending and receiving data, thereby
 * generating shift register interrupts (SR_INT) for us. This means there has
 * to be activity on the ADB bus. The chip will poll to achieve this.
 *
 * The basic ADB state machine was left unchanged from the original MacII code
 * by Alan Cox, which was based on the CUDA driver for PowerMac. 
 * The syntax of the ADB status lines is totally different on MacII,
 * though. MacII uses the states Command -> Even -> Odd -> Even ->...-> Idle
 * for sending and Idle -> Even -> Odd -> Even ->...-> Idle for receiving.
 * Start and end of a receive packet are signalled by asserting /IRQ on the
 * interrupt line (/IRQ means the CTLR_IRQ bit in port B; not to be confused
 * with the VIA shift register interrupt. /IRQ never actually interrupts the
 * processor, it's just an ordinary input.)
 */
static irqreturn_t macii_interrupt(int irq, void *arg)
{
	int x;
	static int entered;
	struct adb_request *req;

	if (!arg) {
		/* Clear the SR IRQ flag when polling. */
		if (via[IFR] & SR_INT)
			via[IFR] = SR_INT;
		else
			return IRQ_NONE;
	}

	BUG_ON(entered++);

	last_status = status;
	status = via[B] & (ST_MASK|CTLR_IRQ);

	switch (macii_state) {
		case idle:
			if (reading_reply) {
				reply_ptr = current_req->reply;
			} else {
				BUG_ON(current_req != NULL);
				reply_ptr = reply_buf;
			}

			x = via[SR];

			if ((status & CTLR_IRQ) && (x == 0xFF)) {
				/* Bus timeout without SRQ sequence:
				 *     data is "FF" while CTLR_IRQ is "H"
				 */
				reply_len = 0;
				srq_asserted = 0;
				macii_state = read_done;
			} else {
				macii_state = reading;
				*reply_ptr = x;
				reply_len = 1;
			}

			/* set ADB state = even for first data byte */
			via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
			break;

		case sending:
			req = current_req;
			if (data_index >= req->nbytes) {
				req->sent = 1;
				macii_state = idle;

				if (req->reply_expected) {
					reading_reply = 1;
				} else {
					req->complete = 1;
					current_req = req->next;
					if (req->done) (*req->done)(req);

					if (current_req)
						macii_start();
					else
						if (need_autopoll())
							macii_autopoll(autopoll_devs);
				}

				if (macii_state == idle) {
					/* reset to shift in */
					via[ACR] &= ~SR_OUT;
					x = via[SR];
					/* set ADB state idle - might get SRQ */
					via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
				}
			} else {
				via[SR] = req->data[data_index++];

				if ( (via[B] & ST_MASK) == ST_CMD ) {
					/* just sent the command byte, set to EVEN */
					via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
				} else {
					/* invert state bits, toggle ODD/EVEN */
					via[B] ^= ST_MASK;
				}
			}
			break;

		case reading:
			x = via[SR];
			BUG_ON((status & ST_MASK) == ST_CMD ||
			       (status & ST_MASK) == ST_IDLE);

			/* Bus timeout with SRQ sequence:
			 *     data is "XX FF"      while CTLR_IRQ is "L L"
			 * End of packet without SRQ sequence:
			 *     data is "XX...YY 00" while CTLR_IRQ is "L...H L"
			 * End of packet SRQ sequence:
			 *     data is "XX...YY 00" while CTLR_IRQ is "L...L L"
			 * (where XX is the first response byte and
			 * YY is the last byte of valid response data.)
			 */

			srq_asserted = 0;
			if (!(status & CTLR_IRQ)) {
				if (x == 0xFF) {
					if (!(last_status & CTLR_IRQ)) {
						macii_state = read_done;
						reply_len = 0;
						srq_asserted = 1;
					}
				} else if (x == 0x00) {
					macii_state = read_done;
					if (!(last_status & CTLR_IRQ))
						srq_asserted = 1;
				}
			}

			if (macii_state == reading) {
				BUG_ON(reply_len > 15);
				reply_ptr++;
				*reply_ptr = x;
				reply_len++;
			}

			/* invert state bits, toggle ODD/EVEN */
			via[B] ^= ST_MASK;
			break;

		case read_done:
			x = via[SR];

			if (reading_reply) {
				reading_reply = 0;
				req = current_req;
				req->reply_len = reply_len;
				req->complete = 1;
				current_req = req->next;
				if (req->done) (*req->done)(req);
			} else if (reply_len && autopoll_devs)
				adb_input(reply_buf, reply_len, 0);

			macii_state = idle;

			/* SRQ seen before, initiate poll now */
			if (srq_asserted)
				macii_queue_poll();

			if (current_req)
				macii_start();
			else
				if (need_autopoll())
					macii_autopoll(autopoll_devs);

			if (macii_state == idle)
				via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
			break;

		default:
		break;
	}

	entered--;
	return IRQ_HANDLED;
}