drivers/macintosh/via-macii.c

   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 */
 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 */
 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 */
 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) */
 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 */
 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) */
 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 */
 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 */
 301 static void macii_poll(void)
 302 {
 303         macii_interrupt(0, NULL);
 304 }
 305
 306 /* Reset the bus */
 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 */
 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  */
 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 }