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 /* Sanity check for request queue. Doesn't check for cycles. */ 124 static int request_is_queued(struct adb_request *req) { 125 struct adb_request *cur; 126 unsigned long flags; 127 local_irq_save(flags); 128 cur = current_req; 129 while (cur) { 130 if (cur == req) { 131 local_irq_restore(flags); 132 return 1; 133 } 134 cur = cur->next; 135 } 136 local_irq_restore(flags); 137 return 0; 138 } 139 140 /* Check for MacII style ADB */ 141 static int macii_probe(void) 142 { 143 if (macintosh_config->adb_type != MAC_ADB_II) return -ENODEV; 144 145 via = via1; 146 147 printk("adb: Mac II ADB Driver v1.0 for Unified ADB\n"); 148 return 0; 149 } 150 151 /* Initialize the driver */ 152 int macii_init(void) 153 { 154 unsigned long flags; 155 int err; 156 157 local_irq_save(flags); 158 159 err = macii_init_via(); 160 if (err) goto out; 161 162 err = request_irq(IRQ_MAC_ADB, macii_interrupt, 0, "ADB", 163 macii_interrupt); 164 if (err) goto out; 165 166 macii_state = idle; 167 out: 168 local_irq_restore(flags); 169 return err; 170 } 171 172 /* initialize the hardware */ 173 static int macii_init_via(void) 174 { 175 unsigned char x; 176 177 /* We want CTLR_IRQ as input and ST_EVEN | ST_ODD as output lines. */ 178 via[DIRB] = (via[DIRB] | ST_EVEN | ST_ODD) & ~CTLR_IRQ; 179 180 /* Set up state: idle */ 181 via[B] |= ST_IDLE; 182 last_status = via[B] & (ST_MASK|CTLR_IRQ); 183 184 /* Shift register on input */ 185 via[ACR] = (via[ACR] & ~SR_CTRL) | SR_EXT; 186 187 /* Wipe any pending data and int */ 188 x = via[SR]; 189 190 return 0; 191 } 192 193 /* Send an ADB poll (Talk Register 0 command prepended to the request queue) */ 194 static void macii_queue_poll(void) 195 { 196 /* No point polling the active device as it will never assert SRQ, so 197 * poll the next device in the autopoll list. This could leave us 198 * stuck in a polling loop if an unprobed device is asserting SRQ. 199 * In theory, that could only happen if a device was plugged in after 200 * probing started. Unplugging it again will break the cycle. 201 * (Simply polling the next higher device often ends up polling almost 202 * every device (after wrapping around), which takes too long.) 203 */ 204 int device_mask; 205 int next_device; 206 static struct adb_request req; 207 208 if (!autopoll_devs) return; 209 210 device_mask = (1 << (((command_byte & 0xF0) >> 4) + 1)) - 1; 211 if (autopoll_devs & ~device_mask) 212 next_device = ffs(autopoll_devs & ~device_mask) - 1; 213 else 214 next_device = ffs(autopoll_devs) - 1; 215 216 BUG_ON(request_is_queued(&req)); 217 218 adb_request(&req, NULL, ADBREQ_NOSEND, 1, 219 ADB_READREG(next_device, 0)); 220 221 req.sent = 0; 222 req.complete = 0; 223 req.reply_len = 0; 224 req.next = current_req; 225 226 if (current_req != NULL) { 227 current_req = &req; 228 } else { 229 current_req = &req; 230 last_req = &req; 231 } 232 } 233 234 /* Send an ADB request; if sync, poll out the reply 'till it's done */ 235 static int macii_send_request(struct adb_request *req, int sync) 236 { 237 int err; 238 unsigned long flags; 239 240 BUG_ON(request_is_queued(req)); 241 242 local_irq_save(flags); 243 err = macii_write(req); 244 local_irq_restore(flags); 245 246 if (!err && sync) { 247 while (!req->complete) { 248 macii_poll(); 249 } 250 BUG_ON(request_is_queued(req)); 251 } 252 253 return err; 254 } 255 256 /* Send an ADB request (append to request queue) */ 257 static int macii_write(struct adb_request *req) 258 { 259 if (req->nbytes < 2 || req->data[0] != ADB_PACKET || req->nbytes > 15) { 260 req->complete = 1; 261 return -EINVAL; 262 } 263 264 req->next = NULL; 265 req->sent = 0; 266 req->complete = 0; 267 req->reply_len = 0; 268 269 if (current_req != NULL) { 270 last_req->next = req; 271 last_req = req; 272 } else { 273 current_req = req; 274 last_req = req; 275 if (macii_state == idle) macii_start(); 276 } 277 return 0; 278 } 279 280 /* Start auto-polling */ 281 static int macii_autopoll(int devs) 282 { 283 static struct adb_request req; 284 unsigned long flags; 285 int err = 0; 286 287 /* bit 1 == device 1, and so on. */ 288 autopoll_devs = devs & 0xFFFE; 289 290 if (!autopoll_devs) return 0; 291 292 local_irq_save(flags); 293 294 if (current_req == NULL) { 295 /* Send a Talk Reg 0. The controller will repeatedly transmit 296 * this as long as it is idle. 297 */ 298 adb_request(&req, NULL, ADBREQ_NOSEND, 1, 299 ADB_READREG(ffs(autopoll_devs) - 1, 0)); 300 err = macii_write(&req); 301 } 302 303 local_irq_restore(flags); 304 return err; 305 } 306 307 static inline int need_autopoll(void) { 308 /* Was the last command Talk Reg 0 309 * and is the target on the autopoll list? 310 */ 311 if ((command_byte & 0x0F) == 0x0C && 312 ((1 << ((command_byte & 0xF0) >> 4)) & autopoll_devs)) 313 return 0; 314 return 1; 315 } 316 317 /* Prod the chip without interrupts */ 318 static void macii_poll(void) 319 { 320 disable_irq(IRQ_MAC_ADB); 321 macii_interrupt(0, NULL); 322 enable_irq(IRQ_MAC_ADB); 323 } 324 325 /* Reset the bus */ 326 static int macii_reset_bus(void) 327 { 328 static struct adb_request req; 329 330 if (request_is_queued(&req)) 331 return 0; 332 333 /* Command = 0, Address = ignored */ 334 adb_request(&req, NULL, 0, 1, ADB_BUSRESET); 335 336 /* Don't want any more requests during the Global Reset low time. */ 337 udelay(3000); 338 339 return 0; 340 } 341 342 /* Start sending ADB packet */ 343 static void macii_start(void) 344 { 345 struct adb_request *req; 346 347 req = current_req; 348 349 BUG_ON(req == NULL); 350 351 BUG_ON(macii_state != idle); 352 353 /* Now send it. Be careful though, that first byte of the request 354 * is actually ADB_PACKET; the real data begins at index 1! 355 * And req->nbytes is the number of bytes of real data plus one. 356 */ 357 358 /* store command byte */ 359 command_byte = req->data[1]; 360 /* Output mode */ 361 via[ACR] |= SR_OUT; 362 /* Load data */ 363 via[SR] = req->data[1]; 364 /* set ADB state to 'command' */ 365 via[B] = (via[B] & ~ST_MASK) | ST_CMD; 366 367 macii_state = sending; 368 data_index = 2; 369 } 370 371 /* 372 * The notorious ADB interrupt handler - does all of the protocol handling. 373 * Relies on the ADB controller sending and receiving data, thereby 374 * generating shift register interrupts (SR_INT) for us. This means there has 375 * to be activity on the ADB bus. The chip will poll to achieve this. 376 * 377 * The basic ADB state machine was left unchanged from the original MacII code 378 * by Alan Cox, which was based on the CUDA driver for PowerMac. 379 * The syntax of the ADB status lines is totally different on MacII, 380 * though. MacII uses the states Command -> Even -> Odd -> Even ->...-> Idle 381 * for sending and Idle -> Even -> Odd -> Even ->...-> Idle for receiving. 382 * Start and end of a receive packet are signalled by asserting /IRQ on the 383 * interrupt line (/IRQ means the CTLR_IRQ bit in port B; not to be confused 384 * with the VIA shift register interrupt. /IRQ never actually interrupts the 385 * processor, it's just an ordinary input.) 386 */ 387 static irqreturn_t macii_interrupt(int irq, void *arg) 388 { 389 int x; 390 static int entered; 391 struct adb_request *req; 392 393 if (!arg) { 394 /* Clear the SR IRQ flag when polling. */ 395 if (via[IFR] & SR_INT) 396 via[IFR] = SR_INT; 397 else 398 return IRQ_NONE; 399 } 400 401 BUG_ON(entered++); 402 403 last_status = status; 404 status = via[B] & (ST_MASK|CTLR_IRQ); 405 406 switch (macii_state) { 407 case idle: 408 if (reading_reply) { 409 reply_ptr = current_req->reply; 410 } else { 411 BUG_ON(current_req != NULL); 412 reply_ptr = reply_buf; 413 } 414 415 x = via[SR]; 416 417 if ((status & CTLR_IRQ) && (x == 0xFF)) { 418 /* Bus timeout without SRQ sequence: 419 * data is "FF" while CTLR_IRQ is "H" 420 */ 421 reply_len = 0; 422 srq_asserted = 0; 423 macii_state = read_done; 424 } else { 425 macii_state = reading; 426 *reply_ptr = x; 427 reply_len = 1; 428 } 429 430 /* set ADB state = even for first data byte */ 431 via[B] = (via[B] & ~ST_MASK) | ST_EVEN; 432 break; 433 434 case sending: 435 req = current_req; 436 if (data_index >= req->nbytes) { 437 req->sent = 1; 438 macii_state = idle; 439 440 if (req->reply_expected) { 441 reading_reply = 1; 442 } else { 443 req->complete = 1; 444 current_req = req->next; 445 if (req->done) (*req->done)(req); 446 447 if (current_req) 448 macii_start(); 449 else 450 if (need_autopoll()) 451 macii_autopoll(autopoll_devs); 452 } 453 454 if (macii_state == idle) { 455 /* reset to shift in */ 456 via[ACR] &= ~SR_OUT; 457 x = via[SR]; 458 /* set ADB state idle - might get SRQ */ 459 via[B] = (via[B] & ~ST_MASK) | ST_IDLE; 460 } 461 } else { 462 via[SR] = req->data[data_index++]; 463 464 if ( (via[B] & ST_MASK) == ST_CMD ) { 465 /* just sent the command byte, set to EVEN */ 466 via[B] = (via[B] & ~ST_MASK) | ST_EVEN; 467 } else { 468 /* invert state bits, toggle ODD/EVEN */ 469 via[B] ^= ST_MASK; 470 } 471 } 472 break; 473 474 case reading: 475 x = via[SR]; 476 BUG_ON((status & ST_MASK) == ST_CMD || 477 (status & ST_MASK) == ST_IDLE); 478 479 /* Bus timeout with SRQ sequence: 480 * data is "XX FF" while CTLR_IRQ is "L L" 481 * End of packet without SRQ sequence: 482 * data is "XX...YY 00" while CTLR_IRQ is "L...H L" 483 * End of packet SRQ sequence: 484 * data is "XX...YY 00" while CTLR_IRQ is "L...L L" 485 * (where XX is the first response byte and 486 * YY is the last byte of valid response data.) 487 */ 488 489 srq_asserted = 0; 490 if (!(status & CTLR_IRQ)) { 491 if (x == 0xFF) { 492 if (!(last_status & CTLR_IRQ)) { 493 macii_state = read_done; 494 reply_len = 0; 495 srq_asserted = 1; 496 } 497 } else if (x == 0x00) { 498 macii_state = read_done; 499 if (!(last_status & CTLR_IRQ)) 500 srq_asserted = 1; 501 } 502 } 503 504 if (macii_state == reading) { 505 BUG_ON(reply_len > 15); 506 reply_ptr++; 507 *reply_ptr = x; 508 reply_len++; 509 } 510 511 /* invert state bits, toggle ODD/EVEN */ 512 via[B] ^= ST_MASK; 513 break; 514 515 case read_done: 516 x = via[SR]; 517 518 if (reading_reply) { 519 reading_reply = 0; 520 req = current_req; 521 req->reply_len = reply_len; 522 req->complete = 1; 523 current_req = req->next; 524 if (req->done) (*req->done)(req); 525 } else if (reply_len && autopoll_devs) 526 adb_input(reply_buf, reply_len, 0); 527 528 macii_state = idle; 529 530 /* SRQ seen before, initiate poll now */ 531 if (srq_asserted) 532 macii_queue_poll(); 533 534 if (current_req) 535 macii_start(); 536 else 537 if (need_autopoll()) 538 macii_autopoll(autopoll_devs); 539 540 if (macii_state == idle) 541 via[B] = (via[B] & ~ST_MASK) | ST_IDLE; 542 break; 543 544 default: 545 break; 546 } 547 548 entered--; 549 return IRQ_HANDLED; 550 } 551