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 } 533