linux/drivers/macintosh/via-macii.c
<<
>>
Prefs
   1/*
   2 * Device driver for the via ADB on (many) Mac II-class machines
   3 *
   4 * Based on the original ADB keyboard handler Copyright (c) 1997 Alan Cox
   5 * Also derived from code Copyright (C) 1996 Paul Mackerras.
   6 *
   7 * With various updates provided over the years by Michael Schmitz,
   8 * Guideo Koerber and others.
   9 *
  10 * Rewrite for Unified ADB by Joshua M. Thompson (funaho@jurai.org)
  11 *
  12 * 1999-08-02 (jmt) - Initial rewrite for Unified ADB.
  13 * 2000-03-29 Tony Mantler <tonym@mac.linux-m68k.org>
  14 *                              - Big overhaul, should actually work now.
  15 * 2006-12-31 Finn Thain <fthain@telegraphics.com.au> - Another overhaul.
  16 *
  17 * Suggested reading:
  18 *   Inside Macintosh, ch. 5 ADB Manager
  19 *   Guide to the Macinstosh Family Hardware, ch. 8 Apple Desktop Bus
  20 *   Rockwell R6522 VIA datasheet
  21 *
  22 * Apple's "ADB Analyzer" bus sniffer is invaluable:
  23 *   ftp://ftp.apple.com/developer/Tool_Chest/Devices_-_Hardware/Apple_Desktop_Bus/
  24 */
  25 
  26#include <stdarg.h>
  27#include <linux/types.h>
  28#include <linux/errno.h>
  29#include <linux/kernel.h>
  30#include <linux/delay.h>
  31#include <linux/adb.h>
  32#include <linux/interrupt.h>
  33#include <linux/init.h>
  34#include <asm/macintosh.h>
  35#include <asm/macints.h>
  36#include <asm/mac_via.h>
  37
  38static volatile unsigned char *via;
  39
  40/* VIA registers - spaced 0x200 bytes apart */
  41#define RS              0x200           /* skip between registers */
  42#define B               0               /* B-side data */
  43#define A               RS              /* A-side data */
  44#define DIRB            (2*RS)          /* B-side direction (1=output) */
  45#define DIRA            (3*RS)          /* A-side direction (1=output) */
  46#define T1CL            (4*RS)          /* Timer 1 ctr/latch (low 8 bits) */
  47#define T1CH            (5*RS)          /* Timer 1 counter (high 8 bits) */
  48#define T1LL            (6*RS)          /* Timer 1 latch (low 8 bits) */
  49#define T1LH            (7*RS)          /* Timer 1 latch (high 8 bits) */
  50#define T2CL            (8*RS)          /* Timer 2 ctr/latch (low 8 bits) */
  51#define T2CH            (9*RS)          /* Timer 2 counter (high 8 bits) */
  52#define SR              (10*RS)         /* Shift register */
  53#define ACR             (11*RS)         /* Auxiliary control register */
  54#define PCR             (12*RS)         /* Peripheral control register */
  55#define IFR             (13*RS)         /* Interrupt flag register */
  56#define IER             (14*RS)         /* Interrupt enable register */
  57#define ANH             (15*RS)         /* A-side data, no handshake */
  58
  59/* Bits in B data register: all active low */
  60#define CTLR_IRQ        0x08            /* Controller rcv status (input) */
  61#define ST_MASK         0x30            /* mask for selecting ADB state bits */
  62
  63/* Bits in ACR */
  64#define SR_CTRL         0x1c            /* Shift register control bits */
  65#define SR_EXT          0x0c            /* Shift on external clock */
  66#define SR_OUT          0x10            /* Shift out if 1 */
  67
  68/* Bits in IFR and IER */
  69#define IER_SET         0x80            /* set bits in IER */
  70#define IER_CLR         0               /* clear bits in IER */
  71#define SR_INT          0x04            /* Shift register full/empty */
  72
  73/* ADB transaction states according to GMHW */
  74#define ST_CMD          0x00            /* ADB state: command byte */
  75#define ST_EVEN         0x10            /* ADB state: even data byte */
  76#define ST_ODD          0x20            /* ADB state: odd data byte */
  77#define ST_IDLE         0x30            /* ADB state: idle, nothing to send */
  78
  79static int  macii_init_via(void);
  80static void macii_start(void);
  81static irqreturn_t macii_interrupt(int irq, void *arg);
  82static void macii_queue_poll(void);
  83
  84static int macii_probe(void);
  85static int macii_init(void);
  86static int macii_send_request(struct adb_request *req, int sync);
  87static int macii_write(struct adb_request *req);
  88static int macii_autopoll(int devs);
  89static void macii_poll(void);
  90static int macii_reset_bus(void);
  91
  92struct adb_driver via_macii_driver = {
  93        "Mac II",
  94        macii_probe,
  95        macii_init,
  96        macii_send_request,
  97        macii_autopoll,
  98        macii_poll,
  99        macii_reset_bus
 100};
 101
 102static enum macii_state {
 103        idle,
 104        sending,
 105        reading,
 106        read_done,
 107} macii_state;
 108
 109static struct adb_request *current_req; /* first request struct in the queue */
 110static struct adb_request *last_req;     /* last request struct in the queue */
 111static unsigned char reply_buf[16];        /* storage for autopolled replies */
 112static unsigned char *reply_ptr;     /* next byte in reply_buf or req->reply */
 113static int reading_reply;        /* store reply in reply_buf else req->reply */
 114static int data_index;      /* index of the next byte to send from req->data */
 115static int reply_len; /* number of bytes received in reply_buf or req->reply */
 116static int status;          /* VIA's ADB status bits captured upon interrupt */
 117static int last_status;              /* status bits as at previous interrupt */
 118static int srq_asserted;     /* have to poll for the device that asserted it */
 119static int command_byte;         /* the most recent command byte transmitted */
 120static int autopoll_devs;      /* bits set are device addresses to be polled */
 121
 122/* Sanity check for request queue. Doesn't check for cycles. */
 123static int request_is_queued(struct adb_request *req) {
 124        struct adb_request *cur;
 125        unsigned long flags;
 126        local_irq_save(flags);
 127        cur = current_req;
 128        while (cur) {
 129                if (cur == req) {
 130                        local_irq_restore(flags);
 131                        return 1;
 132                }
 133                cur = cur->next;
 134        }
 135        local_irq_restore(flags);
 136        return 0;
 137}
 138
 139/* Check for MacII style ADB */
 140static int macii_probe(void)
 141{
 142        if (macintosh_config->adb_type != MAC_ADB_II) return -ENODEV;
 143
 144        via = via1;
 145
 146        printk("adb: Mac II ADB Driver v1.0 for Unified ADB\n");
 147        return 0;
 148}
 149
 150/* Initialize the driver */
 151int macii_init(void)
 152{
 153        unsigned long flags;
 154        int err;
 155        
 156        local_irq_save(flags);
 157        
 158        err = macii_init_via();
 159        if (err) goto out;
 160
 161        err = request_irq(IRQ_MAC_ADB, macii_interrupt, 0, "ADB",
 162                          macii_interrupt);
 163        if (err) goto out;
 164
 165        macii_state = idle;
 166out:
 167        local_irq_restore(flags);
 168        return err;
 169}
 170
 171/* initialize the hardware */   
 172static int macii_init_via(void)
 173{
 174        unsigned char x;
 175
 176        /* We want CTLR_IRQ as input and ST_EVEN | ST_ODD as output lines. */
 177        via[DIRB] = (via[DIRB] | ST_EVEN | ST_ODD) & ~CTLR_IRQ;
 178
 179        /* Set up state: idle */
 180        via[B] |= ST_IDLE;
 181        last_status = via[B] & (ST_MASK|CTLR_IRQ);
 182
 183        /* Shift register on input */
 184        via[ACR] = (via[ACR] & ~SR_CTRL) | SR_EXT;
 185
 186        /* Wipe any pending data and int */
 187        x = via[SR];
 188
 189        return 0;
 190}
 191
 192/* Send an ADB poll (Talk Register 0 command prepended to the request queue) */
 193static void macii_queue_poll(void)
 194{
 195        /* No point polling the active device as it will never assert SRQ, so
 196         * poll the next device in the autopoll list. This could leave us
 197         * stuck in a polling loop if an unprobed device is asserting SRQ.
 198         * In theory, that could only happen if a device was plugged in after
 199         * probing started. Unplugging it again will break the cycle.
 200         * (Simply polling the next higher device often ends up polling almost
 201         * every device (after wrapping around), which takes too long.)
 202         */
 203        int device_mask;
 204        int next_device;
 205        static struct adb_request req;
 206
 207        if (!autopoll_devs) return;
 208
 209        device_mask = (1 << (((command_byte & 0xF0) >> 4) + 1)) - 1;
 210        if (autopoll_devs & ~device_mask)
 211                next_device = ffs(autopoll_devs & ~device_mask) - 1;
 212        else
 213                next_device = ffs(autopoll_devs) - 1;
 214
 215        BUG_ON(request_is_queued(&req));
 216
 217        adb_request(&req, NULL, ADBREQ_NOSEND, 1,
 218                    ADB_READREG(next_device, 0));
 219
 220        req.sent = 0;
 221        req.complete = 0;
 222        req.reply_len = 0;
 223        req.next = current_req;
 224
 225        if (current_req != NULL) {
 226                current_req = &req;
 227        } else {
 228                current_req = &req;
 229                last_req = &req;
 230        }
 231}
 232
 233/* Send an ADB request; if sync, poll out the reply 'till it's done */
 234static int macii_send_request(struct adb_request *req, int sync)
 235{
 236        int err;
 237        unsigned long flags;
 238
 239        BUG_ON(request_is_queued(req));
 240
 241        local_irq_save(flags);
 242        err = macii_write(req);
 243        local_irq_restore(flags);
 244
 245        if (!err && sync) {
 246                while (!req->complete) {
 247                        macii_poll();
 248                }
 249                BUG_ON(request_is_queued(req));
 250        }
 251
 252        return err;
 253}
 254
 255/* Send an ADB request (append to request queue) */
 256static int macii_write(struct adb_request *req)
 257{
 258        if (req->nbytes < 2 || req->data[0] != ADB_PACKET || req->nbytes > 15) {
 259                req->complete = 1;
 260                return -EINVAL;
 261        }
 262        
 263        req->next = NULL;
 264        req->sent = 0;
 265        req->complete = 0;
 266        req->reply_len = 0;
 267
 268        if (current_req != NULL) {
 269                last_req->next = req;
 270                last_req = req;
 271        } else {
 272                current_req = req;
 273                last_req = req;
 274                if (macii_state == idle) macii_start();
 275        }
 276        return 0;
 277}
 278
 279/* Start auto-polling */
 280static int macii_autopoll(int devs)
 281{
 282        static struct adb_request req;
 283        unsigned long flags;
 284        int err = 0;
 285
 286        /* bit 1 == device 1, and so on. */
 287        autopoll_devs = devs & 0xFFFE;
 288
 289        if (!autopoll_devs) return 0;
 290
 291        local_irq_save(flags);
 292
 293        if (current_req == NULL) {
 294                /* Send a Talk Reg 0. The controller will repeatedly transmit
 295                 * this as long as it is idle.
 296                 */
 297                adb_request(&req, NULL, ADBREQ_NOSEND, 1,
 298                            ADB_READREG(ffs(autopoll_devs) - 1, 0));
 299                err = macii_write(&req);
 300        }
 301
 302        local_irq_restore(flags);
 303        return err;
 304}
 305
 306static inline int need_autopoll(void) {
 307        /* Was the last command Talk Reg 0
 308         * and is the target on the autopoll list?
 309         */
 310        if ((command_byte & 0x0F) == 0x0C &&
 311            ((1 << ((command_byte & 0xF0) >> 4)) & autopoll_devs))
 312                return 0;
 313        return 1;
 314}
 315
 316/* Prod the chip without interrupts */
 317static void macii_poll(void)
 318{
 319        disable_irq(IRQ_MAC_ADB);
 320        macii_interrupt(0, NULL);
 321        enable_irq(IRQ_MAC_ADB);
 322}
 323
 324/* Reset the bus */
 325static int macii_reset_bus(void)
 326{
 327        static struct adb_request req;
 328        
 329        if (request_is_queued(&req))
 330                return 0;
 331
 332        /* Command = 0, Address = ignored */
 333        adb_request(&req, NULL, 0, 1, ADB_BUSRESET);
 334
 335        /* Don't want any more requests during the Global Reset low time. */
 336        udelay(3000);
 337
 338        return 0;
 339}
 340
 341/* Start sending ADB packet */
 342static void macii_start(void)
 343{
 344        struct adb_request *req;
 345
 346        req = current_req;
 347
 348        BUG_ON(req == NULL);
 349
 350        BUG_ON(macii_state != idle);
 351
 352        /* Now send it. Be careful though, that first byte of the request
 353         * is actually ADB_PACKET; the real data begins at index 1!
 354         * And req->nbytes is the number of bytes of real data plus one.
 355         */
 356
 357        /* store command byte */
 358        command_byte = req->data[1];
 359        /* Output mode */
 360        via[ACR] |= SR_OUT;
 361        /* Load data */
 362        via[SR] = req->data[1];
 363        /* set ADB state to 'command' */
 364        via[B] = (via[B] & ~ST_MASK) | ST_CMD;
 365
 366        macii_state = sending;
 367        data_index = 2;
 368}
 369
 370/*
 371 * The notorious ADB interrupt handler - does all of the protocol handling.
 372 * Relies on the ADB controller sending and receiving data, thereby
 373 * generating shift register interrupts (SR_INT) for us. This means there has
 374 * to be activity on the ADB bus. The chip will poll to achieve this.
 375 *
 376 * The basic ADB state machine was left unchanged from the original MacII code
 377 * by Alan Cox, which was based on the CUDA driver for PowerMac. 
 378 * The syntax of the ADB status lines is totally different on MacII,
 379 * though. MacII uses the states Command -> Even -> Odd -> Even ->...-> Idle
 380 * for sending and Idle -> Even -> Odd -> Even ->...-> Idle for receiving.
 381 * Start and end of a receive packet are signalled by asserting /IRQ on the
 382 * interrupt line (/IRQ means the CTLR_IRQ bit in port B; not to be confused
 383 * with the VIA shift register interrupt. /IRQ never actually interrupts the
 384 * processor, it's just an ordinary input.)
 385 */
 386static irqreturn_t macii_interrupt(int irq, void *arg)
 387{
 388        int x;
 389        static int entered;
 390        struct adb_request *req;
 391
 392        if (!arg) {
 393                /* Clear the SR IRQ flag when polling. */
 394                if (via[IFR] & SR_INT)
 395                        via[IFR] = SR_INT;
 396                else
 397                        return IRQ_NONE;
 398        }
 399
 400        BUG_ON(entered++);
 401
 402        last_status = status;
 403        status = via[B] & (ST_MASK|CTLR_IRQ);
 404
 405        switch (macii_state) {
 406                case idle:
 407                        if (reading_reply) {
 408                                reply_ptr = current_req->reply;
 409                        } else {
 410                                BUG_ON(current_req != NULL);
 411                                reply_ptr = reply_buf;
 412                        }
 413
 414                        x = via[SR];
 415
 416                        if ((status & CTLR_IRQ) && (x == 0xFF)) {
 417                                /* Bus timeout without SRQ sequence:
 418                                 *     data is "FF" while CTLR_IRQ is "H"
 419                                 */
 420                                reply_len = 0;
 421                                srq_asserted = 0;
 422                                macii_state = read_done;
 423                        } else {
 424                                macii_state = reading;
 425                                *reply_ptr = x;
 426                                reply_len = 1;
 427                        }
 428
 429                        /* set ADB state = even for first data byte */
 430                        via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
 431                        break;
 432
 433                case sending:
 434                        req = current_req;
 435                        if (data_index >= req->nbytes) {
 436                                req->sent = 1;
 437                                macii_state = idle;
 438
 439                                if (req->reply_expected) {
 440                                        reading_reply = 1;
 441                                } else {
 442                                        req->complete = 1;
 443                                        current_req = req->next;
 444                                        if (req->done) (*req->done)(req);
 445
 446                                        if (current_req)
 447                                                macii_start();
 448                                        else
 449                                                if (need_autopoll())
 450                                                        macii_autopoll(autopoll_devs);
 451                                }
 452
 453                                if (macii_state == idle) {
 454                                        /* reset to shift in */
 455                                        via[ACR] &= ~SR_OUT;
 456                                        x = via[SR];
 457                                        /* set ADB state idle - might get SRQ */
 458                                        via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
 459                                }
 460                        } else {
 461                                via[SR] = req->data[data_index++];
 462
 463                                if ( (via[B] & ST_MASK) == ST_CMD ) {
 464                                        /* just sent the command byte, set to EVEN */
 465                                        via[B] = (via[B] & ~ST_MASK) | ST_EVEN;
 466                                } else {
 467                                        /* invert state bits, toggle ODD/EVEN */
 468                                        via[B] ^= ST_MASK;
 469                                }
 470                        }
 471                        break;
 472
 473                case reading:
 474                        x = via[SR];
 475                        BUG_ON((status & ST_MASK) == ST_CMD ||
 476                               (status & ST_MASK) == ST_IDLE);
 477
 478                        /* Bus timeout with SRQ sequence:
 479                         *     data is "XX FF"      while CTLR_IRQ is "L L"
 480                         * End of packet without SRQ sequence:
 481                         *     data is "XX...YY 00" while CTLR_IRQ is "L...H L"
 482                         * End of packet SRQ sequence:
 483                         *     data is "XX...YY 00" while CTLR_IRQ is "L...L L"
 484                         * (where XX is the first response byte and
 485                         * YY is the last byte of valid response data.)
 486                         */
 487
 488                        srq_asserted = 0;
 489                        if (!(status & CTLR_IRQ)) {
 490                                if (x == 0xFF) {
 491                                        if (!(last_status & CTLR_IRQ)) {
 492                                                macii_state = read_done;
 493                                                reply_len = 0;
 494                                                srq_asserted = 1;
 495                                        }
 496                                } else if (x == 0x00) {
 497                                        macii_state = read_done;
 498                                        if (!(last_status & CTLR_IRQ))
 499                                                srq_asserted = 1;
 500                                }
 501                        }
 502
 503                        if (macii_state == reading) {
 504                                BUG_ON(reply_len > 15);
 505                                reply_ptr++;
 506                                *reply_ptr = x;
 507                                reply_len++;
 508                        }
 509
 510                        /* invert state bits, toggle ODD/EVEN */
 511                        via[B] ^= ST_MASK;
 512                        break;
 513
 514                case read_done:
 515                        x = via[SR];
 516
 517                        if (reading_reply) {
 518                                reading_reply = 0;
 519                                req = current_req;
 520                                req->reply_len = reply_len;
 521                                req->complete = 1;
 522                                current_req = req->next;
 523                                if (req->done) (*req->done)(req);
 524                        } else if (reply_len && autopoll_devs)
 525                                adb_input(reply_buf, reply_len, 0);
 526
 527                        macii_state = idle;
 528
 529                        /* SRQ seen before, initiate poll now */
 530                        if (srq_asserted)
 531                                macii_queue_poll();
 532
 533                        if (current_req)
 534                                macii_start();
 535                        else
 536                                if (need_autopoll())
 537                                        macii_autopoll(autopoll_devs);
 538
 539                        if (macii_state == idle)
 540                                via[B] = (via[B] & ~ST_MASK) | ST_IDLE;
 541                        break;
 542
 543                default:
 544                break;
 545        }
 546
 547        entered--;
 548        return IRQ_HANDLED;
 549}
 550
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.