xref: /linux/drivers/macintosh/via-macii.c (revision 621cde16e49b3ecf7d59a8106a20aaebfb4a59a9)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Device driver for the via ADB on (many) Mac II-class machines
4  *
5  * Based on the original ADB keyboard handler Copyright (c) 1997 Alan Cox
6  * Also derived from code Copyright (C) 1996 Paul Mackerras.
7  *
8  * With various updates provided over the years by Michael Schmitz,
9  * Guideo Koerber and others.
10  *
11  * Rewrite for Unified ADB by Joshua M. Thompson (funaho@jurai.org)
12  *
13  * 1999-08-02 (jmt) - Initial rewrite for Unified ADB.
14  * 2000-03-29 Tony Mantler <tonym@mac.linux-m68k.org>
15  *            - Big overhaul, should actually work now.
16  * 2006-12-31 Finn Thain - Another overhaul.
17  *
18  * Suggested reading:
19  *   Inside Macintosh, ch. 5 ADB Manager
20  *   Guide to the Macinstosh Family Hardware, ch. 8 Apple Desktop Bus
21  *   Rockwell R6522 VIA datasheet
22  *
23  * Apple's "ADB Analyzer" bus sniffer is invaluable:
24  *   ftp://ftp.apple.com/developer/Tool_Chest/Devices_-_Hardware/Apple_Desktop_Bus/
25  */
26 #include <linux/types.h>
27 #include <linux/errno.h>
28 #include <linux/kernel.h>
29 #include <linux/delay.h>
30 #include <linux/adb.h>
31 #include <linux/interrupt.h>
32 #include <linux/init.h>
33 #include <asm/macintosh.h>
34 #include <asm/macints.h>
35 #include <asm/mac_via.h>
36 
37 static volatile unsigned char *via;
38 
39 /* VIA registers - spaced 0x200 bytes apart */
40 #define RS		0x200		/* skip between registers */
41 #define B		0		/* B-side data */
42 #define A		RS		/* A-side data */
43 #define DIRB		(2*RS)		/* B-side direction (1=output) */
44 #define DIRA		(3*RS)		/* A-side direction (1=output) */
45 #define T1CL		(4*RS)		/* Timer 1 ctr/latch (low 8 bits) */
46 #define T1CH		(5*RS)		/* Timer 1 counter (high 8 bits) */
47 #define T1LL		(6*RS)		/* Timer 1 latch (low 8 bits) */
48 #define T1LH		(7*RS)		/* Timer 1 latch (high 8 bits) */
49 #define T2CL		(8*RS)		/* Timer 2 ctr/latch (low 8 bits) */
50 #define T2CH		(9*RS)		/* Timer 2 counter (high 8 bits) */
51 #define SR		(10*RS)		/* Shift register */
52 #define ACR		(11*RS)		/* Auxiliary control register */
53 #define PCR		(12*RS)		/* Peripheral control register */
54 #define IFR		(13*RS)		/* Interrupt flag register */
55 #define IER		(14*RS)		/* Interrupt enable register */
56 #define ANH		(15*RS)		/* A-side data, no handshake */
57 
58 /* Bits in B data register: all active low */
59 #define CTLR_IRQ	0x08		/* Controller rcv status (input) */
60 #define ST_MASK		0x30		/* mask for selecting ADB state bits */
61 
62 /* Bits in ACR */
63 #define SR_CTRL		0x1c		/* Shift register control bits */
64 #define SR_EXT		0x0c		/* Shift on external clock */
65 #define SR_OUT		0x10		/* Shift out if 1 */
66 
67 /* Bits in IFR and IER */
68 #define IER_SET		0x80		/* set bits in IER */
69 #define IER_CLR		0		/* clear bits in IER */
70 #define SR_INT		0x04		/* Shift register full/empty */
71 
72 /* ADB transaction states according to GMHW */
73 #define ST_CMD		0x00		/* ADB state: command byte */
74 #define ST_EVEN		0x10		/* ADB state: even data byte */
75 #define ST_ODD		0x20		/* ADB state: odd data byte */
76 #define ST_IDLE		0x30		/* ADB state: idle, nothing to send */
77 
78 /* ADB command byte structure */
79 #define ADDR_MASK	0xF0
80 #define CMD_MASK	0x0F
81 #define OP_MASK		0x0C
82 #define TALK		0x0C
83 
84 static int macii_init_via(void);
85 static void macii_start(void);
86 static irqreturn_t macii_interrupt(int irq, void *arg);
87 static void macii_queue_poll(void);
88 
89 static int macii_probe(void);
90 static int macii_init(void);
91 static int macii_send_request(struct adb_request *req, int sync);
92 static int macii_write(struct adb_request *req);
93 static int macii_autopoll(int devs);
94 static void macii_poll(void);
95 static int macii_reset_bus(void);
96 
97 struct adb_driver via_macii_driver = {
98 	.name         = "Mac II",
99 	.probe        = macii_probe,
100 	.init         = macii_init,
101 	.send_request = macii_send_request,
102 	.autopoll     = macii_autopoll,
103 	.poll         = macii_poll,
104 	.reset_bus    = macii_reset_bus,
105 };
106 
107 static enum macii_state {
108 	idle,
109 	sending,
110 	reading,
111 } macii_state;
112 
113 static struct adb_request *current_req; /* first request struct in the queue */
114 static struct adb_request *last_req;     /* last request struct in the queue */
115 static unsigned char reply_buf[16];        /* storage for autopolled replies */
116 static unsigned char *reply_ptr;     /* next byte in reply_buf or req->reply */
117 static bool reading_reply;       /* store reply in reply_buf else req->reply */
118 static int data_index;      /* index of the next byte to send from req->data */
119 static int reply_len; /* number of bytes received in reply_buf or req->reply */
120 static int status;          /* VIA's ADB status bits captured upon interrupt */
121 static bool bus_timeout;                   /* no data was sent by the device */
122 static bool srq_asserted;    /* have to poll for the device that asserted it */
123 static u8 last_cmd;              /* the most recent command byte transmitted */
124 static u8 last_talk_cmd;    /* the most recent Talk command byte transmitted */
125 static u8 last_poll_cmd; /* the most recent Talk R0 command byte transmitted */
126 static unsigned int autopoll_devs;  /* bits set are device addresses to poll */
127 
128 /* Check for MacII style ADB */
macii_probe(void)129 static int macii_probe(void)
130 {
131 	if (macintosh_config->adb_type != MAC_ADB_II)
132 		return -ENODEV;
133 
134 	via = via1;
135 
136 	pr_info("adb: Mac II ADB Driver v1.0 for Unified ADB\n");
137 	return 0;
138 }
139 
140 /* Initialize the driver */
macii_init(void)141 static int macii_init(void)
142 {
143 	int err;
144 
145 	err = macii_init_via();
146 	if (err)
147 		return err;
148 
149 	err = request_irq(IRQ_MAC_ADB, macii_interrupt, 0, "ADB",
150 			  macii_interrupt);
151 	if (err)
152 		return err;
153 
154 	macii_state = idle;
155 	return 0;
156 }
157 
158 /* initialize the hardware */
macii_init_via(void)159 static int macii_init_via(void)
160 {
161 	unsigned char x;
162 
163 	/* We want CTLR_IRQ as input and ST_EVEN | ST_ODD as output lines. */
164 	via[DIRB] = (via[DIRB] | ST_EVEN | ST_ODD) & ~CTLR_IRQ;
165 
166 	/* Set up state: idle */
167 	via[B] |= ST_IDLE;
168 
169 	/* Shift register on input */
170 	via[ACR] = (via[ACR] & ~SR_CTRL) | SR_EXT;
171 
172 	/* Wipe any pending data and int */
173 	x = via[SR];
174 
175 	return 0;
176 }
177 
178 /* Send an ADB poll (Talk Register 0 command prepended to the request queue) */
macii_queue_poll(void)179 static void macii_queue_poll(void)
180 {
181 	static struct adb_request req;
182 	unsigned char poll_command;
183 	unsigned int poll_addr;
184 
185 	/* This only polls devices in the autopoll list, which assumes that
186 	 * unprobed devices never assert SRQ. That could happen if a device was
187 	 * plugged in after the adb bus scan. Unplugging it again will resolve
188 	 * the problem. This behaviour is similar to MacOS.
189 	 */
190 	if (!autopoll_devs)
191 		return;
192 
193 	/* The device most recently polled may not be the best device to poll
194 	 * right now. Some other device(s) may have signalled SRQ (the active
195 	 * device won't do that). Or the autopoll list may have been changed.
196 	 * Try polling the next higher address.
197 	 */
198 	poll_addr = (last_poll_cmd & ADDR_MASK) >> 4;
199 	if ((srq_asserted && last_cmd == last_poll_cmd) ||
200 	    !(autopoll_devs & (1 << poll_addr))) {
201 		unsigned int higher_devs;
202 
203 		higher_devs = autopoll_devs & -(1 << (poll_addr + 1));
204 		poll_addr = ffs(higher_devs ? higher_devs : autopoll_devs) - 1;
205 	}
206 
207 	/* Send a Talk Register 0 command */
208 	poll_command = ADB_READREG(poll_addr, 0);
209 
210 	/* No need to repeat this Talk command. The transceiver will do that
211 	 * as long as it is idle.
212 	 */
213 	if (poll_command == last_cmd)
214 		return;
215 
216 	adb_request(&req, NULL, ADBREQ_NOSEND, 1, poll_command);
217 
218 	req.sent = 0;
219 	req.complete = 0;
220 	req.reply_len = 0;
221 	req.next = current_req;
222 
223 	if (WARN_ON(current_req)) {
224 		current_req = &req;
225 	} else {
226 		current_req = &req;
227 		last_req = &req;
228 	}
229 }
230 
231 /* Send an ADB request; if sync, poll out the reply 'till it's done */
macii_send_request(struct adb_request * req,int sync)232 static int macii_send_request(struct adb_request *req, int sync)
233 {
234 	int err;
235 
236 	err = macii_write(req);
237 	if (err)
238 		return err;
239 
240 	if (sync)
241 		while (!req->complete)
242 			macii_poll();
243 
244 	return 0;
245 }
246 
247 /* Send an ADB request (append to request queue) */
macii_write(struct adb_request * req)248 static int macii_write(struct adb_request *req)
249 {
250 	unsigned long flags;
251 
252 	if (req->nbytes < 2 || req->data[0] != ADB_PACKET || req->nbytes > 15) {
253 		req->complete = 1;
254 		return -EINVAL;
255 	}
256 
257 	req->next = NULL;
258 	req->sent = 0;
259 	req->complete = 0;
260 	req->reply_len = 0;
261 
262 	local_irq_save(flags);
263 
264 	if (current_req != NULL) {
265 		last_req->next = req;
266 		last_req = req;
267 	} else {
268 		current_req = req;
269 		last_req = req;
270 		if (macii_state == idle)
271 			macii_start();
272 	}
273 
274 	local_irq_restore(flags);
275 
276 	return 0;
277 }
278 
279 /* Start auto-polling */
macii_autopoll(int devs)280 static int macii_autopoll(int devs)
281 {
282 	unsigned long flags;
283 
284 	local_irq_save(flags);
285 
286 	/* bit 1 == device 1, and so on. */
287 	autopoll_devs = (unsigned int)devs & 0xFFFE;
288 
289 	if (!current_req) {
290 		macii_queue_poll();
291 		if (current_req && macii_state == idle)
292 			macii_start();
293 	}
294 
295 	local_irq_restore(flags);
296 
297 	return 0;
298 }
299 
300 /* Prod the chip without interrupts */
macii_poll(void)301 static void macii_poll(void)
302 {
303 	macii_interrupt(0, NULL);
304 }
305 
306 /* Reset the bus */
macii_reset_bus(void)307 static int macii_reset_bus(void)
308 {
309 	struct adb_request req;
310 
311 	/* Command = 0, Address = ignored */
312 	adb_request(&req, NULL, ADBREQ_NOSEND, 1, ADB_BUSRESET);
313 	macii_send_request(&req, 1);
314 
315 	/* Don't want any more requests during the Global Reset low time. */
316 	udelay(3000);
317 
318 	return 0;
319 }
320 
321 /* Start sending ADB packet */
macii_start(void)322 static void macii_start(void)
323 {
324 	struct adb_request *req;
325 
326 	req = current_req;
327 
328 	/* Now send it. Be careful though, that first byte of the request
329 	 * is actually ADB_PACKET; the real data begins at index 1!
330 	 * And req->nbytes is the number of bytes of real data plus one.
331 	 */
332 
333 	/* Output mode */
334 	via[ACR] |= SR_OUT;
335 	/* Load data */
336 	via[SR] = req->data[1];
337 	/* set ADB state to 'command' */
338 	via[B] = (via[B] & ~ST_MASK) | ST_CMD;
339 
340 	macii_state = sending;
341 	data_index = 2;
342 
343 	bus_timeout = false;
344 	srq_asserted = false;
345 }
346 
347 /*
348  * The notorious ADB interrupt handler - does all of the protocol handling.
349  * Relies on the ADB controller sending and receiving data, thereby
350  * generating shift register interrupts (SR_INT) for us. This means there has
351  * to be activity on the ADB bus. The chip will poll to achieve this.
352  *
353  * The VIA Port B output signalling works as follows. After the ADB transceiver
354  * sees a transition on the PB4 and PB5 lines it will crank over the VIA shift
355  * register which eventually raises the SR_INT interrupt. The PB4/PB5 outputs
356  * are toggled with each byte as the ADB transaction progresses.
357  *
358  * Request with no reply expected (and empty transceiver buffer):
359  *     CMD -> IDLE
360  * Request with expected reply packet (or with buffered autopoll packet):
361  *     CMD -> EVEN -> ODD -> EVEN -> ... -> IDLE
362  * Unsolicited packet:
363  *     IDLE -> EVEN -> ODD -> EVEN -> ... -> IDLE
364  */
macii_interrupt(int irq,void * arg)365 static irqreturn_t macii_interrupt(int irq, void *arg)
366 {
367 	int x;
368 	struct adb_request *req;
369 	unsigned long flags;
370 
371 	local_irq_save(flags);
372 
373 	if (!arg) {
374 		/* Clear the SR IRQ flag when polling. */
375 		if (via[IFR] & SR_INT)
376 			via[IFR] = SR_INT;
377 		else {
378 			local_irq_restore(flags);
379 			return IRQ_NONE;
380 		}
381 	}
382 
383 	status = via[B] & (ST_MASK | CTLR_IRQ);
384 
385 	switch (macii_state) {
386 	case idle:
387 		WARN_ON((status & ST_MASK) != ST_IDLE);
388 
389 		reply_ptr = reply_buf;
390 		reading_reply = false;
391 
392 		bus_timeout = false;
393 		srq_asserted = false;
394 
395 		x = via[SR];
396 
397 		if (!(status & CTLR_IRQ)) {
398 			/* /CTLR_IRQ asserted in idle state means we must
399 			 * read an autopoll reply from the transceiver buffer.
400 			 */
401 			macii_state = reading;
402 			*reply_ptr = x;
403 			reply_len = 1;
404 		} else {
405 			/* bus timeout */
406 			reply_len = 0;
407 			break;
408 		}
409 
410 		/* set ADB state = even for first data byte */
411 		via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
412 		break;
413 
414 	case sending:
415 		req = current_req;
416 
417 		if (status == (ST_CMD | CTLR_IRQ)) {
418 			/* /CTLR_IRQ de-asserted after the command byte means
419 			 * the host can continue with the transaction.
420 			 */
421 
422 			/* Store command byte */
423 			last_cmd = req->data[1];
424 			if ((last_cmd & OP_MASK) == TALK) {
425 				last_talk_cmd = last_cmd;
426 				if ((last_cmd & CMD_MASK) == ADB_READREG(0, 0))
427 					last_poll_cmd = last_cmd;
428 			}
429 		}
430 
431 		if (status == ST_CMD) {
432 			/* /CTLR_IRQ asserted after the command byte means we
433 			 * must read an autopoll reply. The first byte was
434 			 * lost because the shift register was an output.
435 			 */
436 			macii_state = reading;
437 
438 			reading_reply = false;
439 			reply_ptr = reply_buf;
440 			*reply_ptr = last_talk_cmd;
441 			reply_len = 1;
442 
443 			/* reset to shift in */
444 			via[ACR] &= ~SR_OUT;
445 			x = via[SR];
446 		} else if (data_index >= req->nbytes) {
447 			req->sent = 1;
448 
449 			if (req->reply_expected) {
450 				macii_state = reading;
451 
452 				reading_reply = true;
453 				reply_ptr = req->reply;
454 				*reply_ptr = req->data[1];
455 				reply_len = 1;
456 
457 				via[ACR] &= ~SR_OUT;
458 				x = via[SR];
459 			} else if ((req->data[1] & OP_MASK) == TALK) {
460 				macii_state = reading;
461 
462 				reading_reply = false;
463 				reply_ptr = reply_buf;
464 				*reply_ptr = req->data[1];
465 				reply_len = 1;
466 
467 				via[ACR] &= ~SR_OUT;
468 				x = via[SR];
469 
470 				req->complete = 1;
471 				current_req = req->next;
472 				if (req->done)
473 					(*req->done)(req);
474 			} else {
475 				macii_state = idle;
476 
477 				req->complete = 1;
478 				current_req = req->next;
479 				if (req->done)
480 					(*req->done)(req);
481 				break;
482 			}
483 		} else {
484 			via[SR] = req->data[data_index++];
485 		}
486 
487 		if ((via[B] & ST_MASK) == ST_CMD) {
488 			/* just sent the command byte, set to EVEN */
489 			via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
490 		} else {
491 			/* invert state bits, toggle ODD/EVEN */
492 			via[B] ^= ST_MASK;
493 		}
494 		break;
495 
496 	case reading:
497 		x = via[SR];
498 		WARN_ON((status & ST_MASK) == ST_CMD ||
499 			(status & ST_MASK) == ST_IDLE);
500 
501 		if (!(status & CTLR_IRQ)) {
502 			if (status == ST_EVEN && reply_len == 1) {
503 				bus_timeout = true;
504 			} else if (status == ST_ODD && reply_len == 2) {
505 				srq_asserted = true;
506 			} else {
507 				macii_state = idle;
508 
509 				if (bus_timeout)
510 					reply_len = 0;
511 
512 				if (reading_reply) {
513 					struct adb_request *req = current_req;
514 
515 					req->reply_len = reply_len;
516 
517 					req->complete = 1;
518 					current_req = req->next;
519 					if (req->done)
520 						(*req->done)(req);
521 				} else if (reply_len && autopoll_devs &&
522 					   reply_buf[0] == last_poll_cmd) {
523 					adb_input(reply_buf, reply_len, 1);
524 				}
525 				break;
526 			}
527 		}
528 
529 		if (reply_len < ARRAY_SIZE(reply_buf)) {
530 			reply_ptr++;
531 			*reply_ptr = x;
532 			reply_len++;
533 		}
534 
535 		/* invert state bits, toggle ODD/EVEN */
536 		via[B] ^= ST_MASK;
537 		break;
538 
539 	default:
540 		break;
541 	}
542 
543 	if (macii_state == idle) {
544 		if (!current_req)
545 			macii_queue_poll();
546 
547 		if (current_req)
548 			macii_start();
549 
550 		if (macii_state == idle) {
551 			via[ACR] &= ~SR_OUT;
552 			x = via[SR];
553 			via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
554 		}
555 	}
556 
557 	local_irq_restore(flags);
558 	return IRQ_HANDLED;
559 }
560