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
27 #include <stdarg.h>
28 #include <linux/types.h>
29 #include <linux/errno.h>
30 #include <linux/kernel.h>
31 #include <linux/delay.h>
32 #include <linux/adb.h>
33 #include <linux/interrupt.h>
34 #include <linux/init.h>
35 #include <asm/macintosh.h>
36 #include <asm/macints.h>
37 #include <asm/mac_via.h>
38
39 static volatile unsigned char *via;
40
41 /* VIA registers - spaced 0x200 bytes apart */
42 #define RS 0x200 /* skip between registers */
43 #define B 0 /* B-side data */
44 #define A RS /* A-side data */
45 #define DIRB (2*RS) /* B-side direction (1=output) */
46 #define DIRA (3*RS) /* A-side direction (1=output) */
47 #define T1CL (4*RS) /* Timer 1 ctr/latch (low 8 bits) */
48 #define T1CH (5*RS) /* Timer 1 counter (high 8 bits) */
49 #define T1LL (6*RS) /* Timer 1 latch (low 8 bits) */
50 #define T1LH (7*RS) /* Timer 1 latch (high 8 bits) */
51 #define T2CL (8*RS) /* Timer 2 ctr/latch (low 8 bits) */
52 #define T2CH (9*RS) /* Timer 2 counter (high 8 bits) */
53 #define SR (10*RS) /* Shift register */
54 #define ACR (11*RS) /* Auxiliary control register */
55 #define PCR (12*RS) /* Peripheral control register */
56 #define IFR (13*RS) /* Interrupt flag register */
57 #define IER (14*RS) /* Interrupt enable register */
58 #define ANH (15*RS) /* A-side data, no handshake */
59
60 /* Bits in B data register: all active low */
61 #define CTLR_IRQ 0x08 /* Controller rcv status (input) */
62 #define ST_MASK 0x30 /* mask for selecting ADB state bits */
63
64 /* Bits in ACR */
65 #define SR_CTRL 0x1c /* Shift register control bits */
66 #define SR_EXT 0x0c /* Shift on external clock */
67 #define SR_OUT 0x10 /* Shift out if 1 */
68
69 /* Bits in IFR and IER */
70 #define IER_SET 0x80 /* set bits in IER */
71 #define IER_CLR 0 /* clear bits in IER */
72 #define SR_INT 0x04 /* Shift register full/empty */
73
74 /* ADB transaction states according to GMHW */
75 #define ST_CMD 0x00 /* ADB state: command byte */
76 #define ST_EVEN 0x10 /* ADB state: even data byte */
77 #define ST_ODD 0x20 /* ADB state: odd data byte */
78 #define ST_IDLE 0x30 /* ADB state: idle, nothing to send */
79
80 static int macii_init_via(void);
81 static void macii_start(void);
82 static irqreturn_t macii_interrupt(int irq, void *arg);
83 static void macii_queue_poll(void);
84
85 static int macii_probe(void);
86 static int macii_init(void);
87 static int macii_send_request(struct adb_request *req, int sync);
88 static int macii_write(struct adb_request *req);
89 static int macii_autopoll(int devs);
90 static void macii_poll(void);
91 static int macii_reset_bus(void);
92
93 struct adb_driver via_macii_driver = {
94 .name = "Mac II",
95 .probe = macii_probe,
96 .init = macii_init,
97 .send_request = macii_send_request,
98 .autopoll = macii_autopoll,
99 .poll = macii_poll,
100 .reset_bus = macii_reset_bus,
101 };
102
103 static enum macii_state {
104 idle,
105 sending,
106 reading,
107 read_done,
108 } macii_state;
109
110 static struct adb_request *current_req; /* first request struct in the queue */
111 static struct adb_request *last_req; /* last request struct in the queue */
112 static unsigned char reply_buf[16]; /* storage for autopolled replies */
113 static unsigned char *reply_ptr; /* next byte in reply_buf or req->reply */
114 static int reading_reply; /* store reply in reply_buf else req->reply */
115 static int data_index; /* index of the next byte to send from req->data */
116 static int reply_len; /* number of bytes received in reply_buf or req->reply */
117 static int status; /* VIA's ADB status bits captured upon interrupt */
118 static int last_status; /* status bits as at previous interrupt */
119 static int srq_asserted; /* have to poll for the device that asserted it */
120 static int command_byte; /* the most recent command byte transmitted */
121 static int autopoll_devs; /* bits set are device addresses to be polled */
122
123 /* Check for MacII style ADB */
124 static int macii_probe(void)
125 {
126 if (macintosh_config->adb_type != MAC_ADB_II)
127 return -ENODEV;
128
129 via = via1;
130
131 pr_info("adb: Mac II ADB Driver v1.0 for Unified ADB\n");
132 return 0;
133 }
134
135 /* Initialize the driver */
136 int macii_init(void)
137 {
138 unsigned long flags;
139 int err;
140
141 local_irq_save(flags);
142
143 err = macii_init_via();
144 if (err)
145 goto out;
146
147 err = request_irq(IRQ_MAC_ADB, macii_interrupt, 0, "ADB",
148 macii_interrupt);
149 if (err)
150 goto out;
151
152 macii_state = idle;
153 out:
154 local_irq_restore(flags);
155 return err;
156 }
157
158 /* initialize the hardware */
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 last_status = via[B] & (ST_MASK | CTLR_IRQ);
169
170 /* Shift register on input */
171 via[ACR] = (via[ACR] & ~SR_CTRL) | SR_EXT;
172
173 /* Wipe any pending data and int */
174 x = via[SR];
175
176 return 0;
177 }
178
179 /* Send an ADB poll (Talk Register 0 command prepended to the request queue) */
180 static void macii_queue_poll(void)
181 {
182 /* No point polling the active device as it will never assert SRQ, so
183 * poll the next device in the autopoll list. This could leave us
184 * stuck in a polling loop if an unprobed device is asserting SRQ.
185 * In theory, that could only happen if a device was plugged in after
186 * probing started. Unplugging it again will break the cycle.
187 * (Simply polling the next higher device often ends up polling almost
188 * every device (after wrapping around), which takes too long.)
189 */
190 int device_mask;
191 int next_device;
192 static struct adb_request req;
193
194 if (!autopoll_devs)
195 return;
196
197 device_mask = (1 << (((command_byte & 0xF0) >> 4) + 1)) - 1;
198 if (autopoll_devs & ~device_mask)
199 next_device = ffs(autopoll_devs & ~device_mask) - 1;
200 else
201 next_device = ffs(autopoll_devs) - 1;
202
203 adb_request(&req, NULL, ADBREQ_NOSEND, 1, ADB_READREG(next_device, 0));
204
205 req.sent = 0;
206 req.complete = 0;
207 req.reply_len = 0;
208 req.next = current_req;
209
210 if (current_req != NULL) {
211 current_req = &req;
212 } else {
213 current_req = &req;
214 last_req = &req;
215 }
216 }
217
218 /* Send an ADB request; if sync, poll out the reply 'till it's done */
219 static int macii_send_request(struct adb_request *req, int sync)
220 {
221 int err;
222
223 err = macii_write(req);
224 if (err)
225 return err;
226
227 if (sync)
228 while (!req->complete)
229 macii_poll();
230
231 return 0;
232 }
233
234 /* Send an ADB request (append to request queue) */
235 static int macii_write(struct adb_request *req)
236 {
237 unsigned long flags;
238
239 if (req->nbytes < 2 || req->data[0] != ADB_PACKET || req->nbytes > 15) {
240 req->complete = 1;
241 return -EINVAL;
242 }
243
244 req->next = NULL;
245 req->sent = 0;
246 req->complete = 0;
247 req->reply_len = 0;
248
249 local_irq_save(flags);
250
251 if (current_req != NULL) {
252 last_req->next = req;
253 last_req = req;
254 } else {
255 current_req = req;
256 last_req = req;
257 if (macii_state == idle)
258 macii_start();
259 }
260
261 local_irq_restore(flags);
262
263 return 0;
264 }
265
266 /* Start auto-polling */
267 static int macii_autopoll(int devs)
268 {
269 static struct adb_request req;
270 unsigned long flags;
271 int err = 0;
272
273 /* bit 1 == device 1, and so on. */
274 autopoll_devs = devs & 0xFFFE;
275
276 if (!autopoll_devs)
277 return 0;
278
279 local_irq_save(flags);
280
281 if (current_req == NULL) {
282 /* Send a Talk Reg 0. The controller will repeatedly transmit
283 * this as long as it is idle.
284 */
285 adb_request(&req, NULL, ADBREQ_NOSEND, 1,
286 ADB_READREG(ffs(autopoll_devs) - 1, 0));
287 err = macii_write(&req);
288 }
289
290 local_irq_restore(flags);
291 return err;
292 }
293
294 static inline int need_autopoll(void)
295 {
296 /* Was the last command Talk Reg 0
297 * and is the target on the autopoll list?
298 */
299 if ((command_byte & 0x0F) == 0x0C &&
300 ((1 << ((command_byte & 0xF0) >> 4)) & autopoll_devs))
301 return 0;
302 return 1;
303 }
304
305 /* Prod the chip without interrupts */
306 static void macii_poll(void)
307 {
308 macii_interrupt(0, NULL);
309 }
310
311 /* Reset the bus */
312 static int macii_reset_bus(void)
313 {
314 static struct adb_request req;
315
316 /* Command = 0, Address = ignored */
317 adb_request(&req, NULL, ADBREQ_NOSEND, 1, ADB_BUSRESET);
318 macii_send_request(&req, 1);
319
320 /* Don't want any more requests during the Global Reset low time. */
321 udelay(3000);
322
323 return 0;
324 }
325
326 /* Start sending ADB packet */
327 static void macii_start(void)
328 {
329 struct adb_request *req;
330
331 req = current_req;
332
333 /* Now send it. Be careful though, that first byte of the request
334 * is actually ADB_PACKET; the real data begins at index 1!
335 * And req->nbytes is the number of bytes of real data plus one.
336 */
337
338 /* store command byte */
339 command_byte = req->data[1];
340 /* Output mode */
341 via[ACR] |= SR_OUT;
342 /* Load data */
343 via[SR] = req->data[1];
344 /* set ADB state to 'command' */
345 via[B] = (via[B] & ~ST_MASK) | ST_CMD;
346
347 macii_state = sending;
348 data_index = 2;
349 }
350
351 /*
352 * The notorious ADB interrupt handler - does all of the protocol handling.
353 * Relies on the ADB controller sending and receiving data, thereby
354 * generating shift register interrupts (SR_INT) for us. This means there has
355 * to be activity on the ADB bus. The chip will poll to achieve this.
356 *
357 * The basic ADB state machine was left unchanged from the original MacII code
358 * by Alan Cox, which was based on the CUDA driver for PowerMac.
359 * The syntax of the ADB status lines is totally different on MacII,
360 * though. MacII uses the states Command -> Even -> Odd -> Even ->...-> Idle
361 * for sending and Idle -> Even -> Odd -> Even ->...-> Idle for receiving.
362 * Start and end of a receive packet are signalled by asserting /IRQ on the
363 * interrupt line (/IRQ means the CTLR_IRQ bit in port B; not to be confused
364 * with the VIA shift register interrupt. /IRQ never actually interrupts the
365 * processor, it's just an ordinary input.)
366 */
367 static irqreturn_t macii_interrupt(int irq, void *arg)
368 {
369 int x;
370 struct adb_request *req;
371 unsigned long flags;
372
373 local_irq_save(flags);
374
375 if (!arg) {
376 /* Clear the SR IRQ flag when polling. */
377 if (via[IFR] & SR_INT)
378 via[IFR] = SR_INT;
379 else {
380 local_irq_restore(flags);
381 return IRQ_NONE;
382 }
383 }
384
385 last_status = status;
386 status = via[B] & (ST_MASK | CTLR_IRQ);
387
388 switch (macii_state) {
389 case idle:
390 if (reading_reply) {
391 reply_ptr = current_req->reply;
392 } else {
393 WARN_ON(current_req);
394 reply_ptr = reply_buf;
395 }
396
397 x = via[SR];
398
399 if ((status & CTLR_IRQ) && (x == 0xFF)) {
400 /* Bus timeout without SRQ sequence:
401 * data is "FF" while CTLR_IRQ is "H"
402 */
403 reply_len = 0;
404 srq_asserted = 0;
405 macii_state = read_done;
406 } else {
407 macii_state = reading;
408 *reply_ptr = x;
409 reply_len = 1;
410 }
411
412 /* set ADB state = even for first data byte */
413 via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
414 break;
415
416 case sending:
417 req = current_req;
418 if (data_index >= req->nbytes) {
419 req->sent = 1;
420 macii_state = idle;
421
422 if (req->reply_expected) {
423 reading_reply = 1;
424 } else {
425 req->complete = 1;
426 current_req = req->next;
427 if (req->done)
428 (*req->done)(req);
429
430 if (current_req)
431 macii_start();
432 else if (need_autopoll())
433 macii_autopoll(autopoll_devs);
434 }
435
436 if (macii_state == idle) {
437 /* reset to shift in */
438 via[ACR] &= ~SR_OUT;
439 x = via[SR];
440 /* set ADB state idle - might get SRQ */
441 via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
442 }
443 } else {
444 via[SR] = req->data[data_index++];
445
446 if ((via[B] & ST_MASK) == ST_CMD) {
447 /* just sent the command byte, set to EVEN */
448 via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
449 } else {
450 /* invert state bits, toggle ODD/EVEN */
451 via[B] ^= ST_MASK;
452 }
453 }
454 break;
455
456 case reading:
457 x = via[SR];
458 WARN_ON((status & ST_MASK) == ST_CMD ||
459 (status & ST_MASK) == ST_IDLE);
460
461 /* Bus timeout with SRQ sequence:
462 * data is "XX FF" while CTLR_IRQ is "L L"
463 * End of packet without SRQ sequence:
464 * data is "XX...YY 00" while CTLR_IRQ is "L...H L"
465 * End of packet SRQ sequence:
466 * data is "XX...YY 00" while CTLR_IRQ is "L...L L"
467 * (where XX is the first response byte and
468 * YY is the last byte of valid response data.)
469 */
470
471 srq_asserted = 0;
472 if (!(status & CTLR_IRQ)) {
473 if (x == 0xFF) {
474 if (!(last_status & CTLR_IRQ)) {
475 macii_state = read_done;
476 reply_len = 0;
477 srq_asserted = 1;
478 }
479 } else if (x == 0x00) {
480 macii_state = read_done;
481 if (!(last_status & CTLR_IRQ))
482 srq_asserted = 1;
483 }
484 }
485
486 if (macii_state == reading &&
487 reply_len < ARRAY_SIZE(reply_buf)) {
488 reply_ptr++;
489 *reply_ptr = x;
490 reply_len++;
491 }
492
493 /* invert state bits, toggle ODD/EVEN */
494 via[B] ^= ST_MASK;
495 break;
496
497 case read_done:
498 x = via[SR];
499
500 if (reading_reply) {
501 reading_reply = 0;
502 req = current_req;
503 req->reply_len = reply_len;
504 req->complete = 1;
505 current_req = req->next;
506 if (req->done)
507 (*req->done)(req);
508 } else if (reply_len && autopoll_devs)
509 adb_input(reply_buf, reply_len, 0);
510
511 macii_state = idle;
512
513 /* SRQ seen before, initiate poll now */
514 if (srq_asserted)
515 macii_queue_poll();
516
517 if (current_req)
518 macii_start();
519 else if (need_autopoll())
520 macii_autopoll(autopoll_devs);
521
522 if (macii_state == idle)
523 via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
524 break;
525
526 default:
527 break;
528 }
529
530 local_irq_restore(flags);
531 return IRQ_HANDLED;
532 }