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
  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 /* ADB command byte structure */
  81 #define ADDR_MASK       0xF0
  82 #define CMD_MASK        0x0F
  83 #define OP_MASK         0x0C
  84 #define TALK            0x0C
  85
  86 static int macii_init_via(void);
  87 static void macii_start(void);
  88 static irqreturn_t macii_interrupt(int irq, void *arg);
  89 static void macii_queue_poll(void);
  90
  91 static int macii_probe(void);
  92 static int macii_init(void);
  93 static int macii_send_request(struct adb_request *req, int sync);
  94 static int macii_write(struct adb_request *req);
  95 static int macii_autopoll(int devs);
  96 static void macii_poll(void);
  97 static int macii_reset_bus(void);
  98
  99 struct adb_driver via_macii_driver = {
 100         .name         = "Mac II",
 101         .probe        = macii_probe,
 102         .init         = macii_init,
 103         .send_request = macii_send_request,
 104         .autopoll     = macii_autopoll,
 105         .poll         = macii_poll,
 106         .reset_bus    = macii_reset_bus,
 107 };
 108
 109 static enum macii_state {
 110         idle,
 111         sending,
 112         reading,
 113 } macii_state;
 114
 115 static struct adb_request *current_req; /* first request struct in the queue */
 116 static struct adb_request *last_req;     /* last request struct in the queue */
 117 static unsigned char reply_buf[16];        /* storage for autopolled replies */
 118 static unsigned char *reply_ptr;     /* next byte in reply_buf or req->reply */
 119 static bool reading_reply;       /* store reply in reply_buf else req->reply */
 120 static int data_index;      /* index of the next byte to send from req->data */
 121 static int reply_len; /* number of bytes received in reply_buf or req->reply */
 122 static int status;          /* VIA's ADB status bits captured upon interrupt */
 123 static bool bus_timeout;                   /* no data was sent by the device */
 124 static bool srq_asserted;    /* have to poll for the device that asserted it */
 125 static u8 last_cmd;              /* the most recent command byte transmitted */
 126 static u8 last_talk_cmd;    /* the most recent Talk command byte transmitted */
 127 static u8 last_poll_cmd; /* the most recent Talk R0 command byte transmitted */
 128 static unsigned int autopoll_devs;  /* bits set are device addresses to poll */
 129
 130 /* Check for MacII style ADB */
 131 static int macii_probe(void)
 132 {
 133         if (macintosh_config->adb_type != MAC_ADB_II)
 134                 return -ENODEV;
 135
 136         via = via1;
 137
 138         pr_info("adb: Mac II ADB Driver v1.0 for Unified ADB\n");
 139         return 0;
 140 }
 141
 142 /* Initialize the driver */
 143 static int macii_init(void)
 144 {
 145         unsigned long flags;
 146         int err;
 147
 148         local_irq_save(flags);
 149
 150         err = macii_init_via();
 151         if (err)
 152                 goto out;
 153
 154         err = request_irq(IRQ_MAC_ADB, macii_interrupt, 0, "ADB",
 155                           macii_interrupt);
 156         if (err)
 157                 goto out;
 158
 159         macii_state = idle;
 160 out:
 161         local_irq_restore(flags);
 162         return err;
 163 }
 164
 165 /* initialize the hardware */
 166 static int macii_init_via(void)
 167 {
 168         unsigned char x;
 169
 170         /* We want CTLR_IRQ as input and ST_EVEN | ST_ODD as output lines. */
 171         via[DIRB] = (via[DIRB] | ST_EVEN | ST_ODD) & ~CTLR_IRQ;
 172
 173         /* Set up state: idle */
 174         via[B] |= ST_IDLE;
 175
 176         /* Shift register on input */
 177         via[ACR] = (via[ACR] & ~SR_CTRL) | SR_EXT;
 178
 179         /* Wipe any pending data and int */
 180         x = via[SR];
 181
 182         return 0;
 183 }
 184
 185 /* Send an ADB poll (Talk Register 0 command prepended to the request queue) */
 186 static void macii_queue_poll(void)
 187 {
 188         static struct adb_request req;
 189         unsigned char poll_command;
 190         unsigned int poll_addr;
 191
 192         /* This only polls devices in the autopoll list, which assumes that
 193          * unprobed devices never assert SRQ. That could happen if a device was
 194          * plugged in after the adb bus scan. Unplugging it again will resolve
 195          * the problem. This behaviour is similar to MacOS.
 196          */
 197         if (!autopoll_devs)
 198                 return;
 199
 200         /* The device most recently polled may not be the best device to poll
 201          * right now. Some other device(s) may have signalled SRQ (the active
 202          * device won't do that). Or the autopoll list may have been changed.
 203          * Try polling the next higher address.
 204          */
 205         poll_addr = (last_poll_cmd & ADDR_MASK) >> 4;
 206         if ((srq_asserted && last_cmd == last_poll_cmd) ||
 207             !(autopoll_devs & (1 << poll_addr))) {
 208                 unsigned int higher_devs;
 209
 210                 higher_devs = autopoll_devs & -(1 << (poll_addr + 1));
 211                 poll_addr = ffs(higher_devs ? higher_devs : autopoll_devs) - 1;
 212         }
 213
 214         /* Send a Talk Register 0 command */
 215         poll_command = ADB_READREG(poll_addr, 0);
 216
 217         /* No need to repeat this Talk command. The transceiver will do that
 218          * as long as it is idle.
 219          */
 220         if (poll_command == last_cmd)
 221                 return;
 222
 223         adb_request(&req, NULL, ADBREQ_NOSEND, 1, poll_command);
 224
 225         req.sent = 0;
 226         req.complete = 0;
 227         req.reply_len = 0;
 228         req.next = current_req;
 229
 230         if (WARN_ON(current_req)) {
 231                 current_req = &req;
 232         } else {
 233                 current_req = &req;
 234                 last_req = &req;
 235         }
 236 }
 237
 238 /* Send an ADB request; if sync, poll out the reply 'till it's done */
 239 static int macii_send_request(struct adb_request *req, int sync)
 240 {
 241         int err;
 242
 243         err = macii_write(req);
 244         if (err)
 245                 return err;
 246
 247         if (sync)
 248                 while (!req->complete)
 249                         macii_poll();
 250
 251         return 0;
 252 }
 253
 254 /* Send an ADB request (append to request queue) */
 255 static int macii_write(struct adb_request *req)
 256 {
 257         unsigned long flags;
 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         local_irq_save(flags);
 270
 271         if (current_req != NULL) {
 272                 last_req->next = req;
 273                 last_req = req;
 274         } else {
 275                 current_req = req;
 276                 last_req = req;
 277                 if (macii_state == idle)
 278                         macii_start();
 279         }
 280
 281         local_irq_restore(flags);
 282
 283         return 0;
 284 }
 285
 286 /* Start auto-polling */
 287 static int macii_autopoll(int devs)
 288 {
 289         unsigned long flags;
 290
 291         local_irq_save(flags);
 292
 293         /* bit 1 == device 1, and so on. */
 294         autopoll_devs = (unsigned int)devs & 0xFFFE;
 295
 296         if (!current_req) {
 297                 macii_queue_poll();
 298                 if (current_req && macii_state == idle)
 299                         macii_start();
 300         }
 301
 302         local_irq_restore(flags);
 303
 304         return 0;
 305 }
 306
 307 /* Prod the chip without interrupts */
 308 static void macii_poll(void)
 309 {
 310         macii_interrupt(0, NULL);
 311 }
 312
 313 /* Reset the bus */
 314 static int macii_reset_bus(void)
 315 {
 316         struct adb_request req;
 317
 318         /* Command = 0, Address = ignored */
 319         adb_request(&req, NULL, ADBREQ_NOSEND, 1, ADB_BUSRESET);
 320         macii_send_request(&req, 1);
 321
 322         /* Don't want any more requests during the Global Reset low time. */
 323         udelay(3000);
 324
 325         return 0;
 326 }
 327
 328 /* Start sending ADB packet */
 329 static void macii_start(void)
 330 {
 331         struct adb_request *req;
 332
 333         req = current_req;
 334
 335         /* Now send it. Be careful though, that first byte of the request
 336          * is actually ADB_PACKET; the real data begins at index 1!
 337          * And req->nbytes is the number of bytes of real data plus one.
 338          */
 339
 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         bus_timeout = false;
 351         srq_asserted = false;
 352 }
 353
 354 /*
 355  * The notorious ADB interrupt handler - does all of the protocol handling.
 356  * Relies on the ADB controller sending and receiving data, thereby
 357  * generating shift register interrupts (SR_INT) for us. This means there has
 358  * to be activity on the ADB bus. The chip will poll to achieve this.
 359  *
 360  * The VIA Port B output signalling works as follows. After the ADB transceiver
 361  * sees a transition on the PB4 and PB5 lines it will crank over the VIA shift
 362  * register which eventually raises the SR_INT interrupt. The PB4/PB5 outputs
 363  * are toggled with each byte as the ADB transaction progresses.
 364  *
 365  * Request with no reply expected (and empty transceiver buffer):
 366  *     CMD -> IDLE
 367  * Request with expected reply packet (or with buffered autopoll packet):
 368  *     CMD -> EVEN -> ODD -> EVEN -> ... -> IDLE
 369  * Unsolicited packet:
 370  *     IDLE -> EVEN -> ODD -> EVEN -> ... -> IDLE
 371  */
 372 static irqreturn_t macii_interrupt(int irq, void *arg)
 373 {
 374         int x;
 375         struct adb_request *req;
 376         unsigned long flags;
 377
 378         local_irq_save(flags);
 379
 380         if (!arg) {
 381                 /* Clear the SR IRQ flag when polling. */
 382                 if (via[IFR] & SR_INT)
 383                         via[IFR] = SR_INT;
 384                 else {
 385                         local_irq_restore(flags);
 386                         return IRQ_NONE;
 387                 }
 388         }
 389
 390         status = via[B] & (ST_MASK | CTLR_IRQ);
 391
 392         switch (macii_state) {
 393         case idle:
 394                 WARN_ON((status & ST_MASK) != ST_IDLE);
 395
 396                 reply_ptr = reply_buf;
 397                 reading_reply = false;
 398
 399                 bus_timeout = false;
 400                 srq_asserted = false;
 401
 402                 x = via[SR];
 403
 404                 if (!(status & CTLR_IRQ)) {
 405                         /* /CTLR_IRQ asserted in idle state means we must
 406                          * read an autopoll reply from the transceiver buffer.
 407                          */
 408                         macii_state = reading;
 409                         *reply_ptr = x;
 410                         reply_len = 1;
 411                 } else {
 412                         /* bus timeout */
 413                         reply_len = 0;
 414                         break;
 415                 }
 416
 417                 /* set ADB state = even for first data byte */
 418                 via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
 419                 break;
 420
 421         case sending:
 422                 req = current_req;
 423
 424                 if (status == (ST_CMD | CTLR_IRQ)) {
 425                         /* /CTLR_IRQ de-asserted after the command byte means
 426                          * the host can continue with the transaction.
 427                          */
 428
 429                         /* Store command byte */
 430                         last_cmd = req->data[1];
 431                         if ((last_cmd & OP_MASK) == TALK) {
 432                                 last_talk_cmd = last_cmd;
 433                                 if ((last_cmd & CMD_MASK) == ADB_READREG(0, 0))
 434                                         last_poll_cmd = last_cmd;
 435                         }
 436                 }
 437
 438                 if (status == ST_CMD) {
 439                         /* /CTLR_IRQ asserted after the command byte means we
 440                          * must read an autopoll reply. The first byte was
 441                          * lost because the shift register was an output.
 442                          */
 443                         macii_state = reading;
 444
 445                         reading_reply = false;
 446                         reply_ptr = reply_buf;
 447                         *reply_ptr = last_talk_cmd;
 448                         reply_len = 1;
 449
 450                         /* reset to shift in */
 451                         via[ACR] &= ~SR_OUT;
 452                         x = via[SR];
 453                 } else if (data_index >= req->nbytes) {
 454                         req->sent = 1;
 455
 456                         if (req->reply_expected) {
 457                                 macii_state = reading;
 458
 459                                 reading_reply = true;
 460                                 reply_ptr = req->reply;
 461                                 *reply_ptr = req->data[1];
 462                                 reply_len = 1;
 463
 464                                 via[ACR] &= ~SR_OUT;
 465                                 x = via[SR];
 466                         } else if ((req->data[1] & OP_MASK) == TALK) {
 467                                 macii_state = reading;
 468
 469                                 reading_reply = false;
 470                                 reply_ptr = reply_buf;
 471                                 *reply_ptr = req->data[1];
 472                                 reply_len = 1;
 473
 474                                 via[ACR] &= ~SR_OUT;
 475                                 x = via[SR];
 476
 477                                 req->complete = 1;
 478                                 current_req = req->next;
 479                                 if (req->done)
 480                                         (*req->done)(req);
 481                         } else {
 482                                 macii_state = idle;
 483
 484                                 req->complete = 1;
 485                                 current_req = req->next;
 486                                 if (req->done)
 487                                         (*req->done)(req);
 488                                 break;
 489                         }
 490                 } else {
 491                         via[SR] = req->data[data_index++];
 492                 }
 493
 494                 if ((via[B] & ST_MASK) == ST_CMD) {
 495                         /* just sent the command byte, set to EVEN */
 496                         via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
 497                 } else {
 498                         /* invert state bits, toggle ODD/EVEN */
 499                         via[B] ^= ST_MASK;
 500                 }
 501                 break;
 502
 503         case reading:
 504                 x = via[SR];
 505                 WARN_ON((status & ST_MASK) == ST_CMD ||
 506                         (status & ST_MASK) == ST_IDLE);
 507
 508                 if (!(status & CTLR_IRQ)) {
 509                         if (status == ST_EVEN && reply_len == 1) {
 510                                 bus_timeout = true;
 511                         } else if (status == ST_ODD && reply_len == 2) {
 512                                 srq_asserted = true;
 513                         } else {
 514                                 macii_state = idle;
 515
 516                                 if (bus_timeout)
 517                                         reply_len = 0;
 518
 519                                 if (reading_reply) {
 520                                         struct adb_request *req = current_req;
 521
 522                                         req->reply_len = reply_len;
 523
 524                                         req->complete = 1;
 525                                         current_req = req->next;
 526                                         if (req->done)
 527                                                 (*req->done)(req);
 528                                 } else if (reply_len && autopoll_devs &&
 529                                            reply_buf[0] == last_poll_cmd) {
 530                                         adb_input(reply_buf, reply_len, 1);
 531                                 }
 532                                 break;
 533                         }
 534                 }
 535
 536                 if (reply_len < ARRAY_SIZE(reply_buf)) {
 537                         reply_ptr++;
 538                         *reply_ptr = x;
 539                         reply_len++;
 540                 }
 541
 542                 /* invert state bits, toggle ODD/EVEN */
 543                 via[B] ^= ST_MASK;
 544                 break;
 545
 546         default:
 547                 break;
 548         }
 549
 550         if (macii_state == idle) {
 551                 if (!current_req)
 552                         macii_queue_poll();
 553
 554                 if (current_req)
 555                         macii_start();
 556
 557                 if (macii_state == idle) {
 558                         via[ACR] &= ~SR_OUT;
 559                         x = via[SR];
 560                         via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
 561                 }
 562         }
 563
 564         local_irq_restore(flags);
 565         return IRQ_HANDLED;
 566 }