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 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 }