src/firmware/scsi.c

   1 //      Copyright (C) 2014 Michael McMaster <michael@codesrc.com>
   2 //
   3 //      This file is part of SCSI2SD.
   4 //
   5 //      SCSI2SD is free software: you can redistribute it and/or modify
   6 //      it under the terms of the GNU General Public License as published by
   7 //      the Free Software Foundation, either version 3 of the License, or
   8 //      (at your option) any later version.
   9 //
  10 //      SCSI2SD is distributed in the hope that it will be useful,
  11 //      but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 //      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 //      GNU General Public License for more details.
  14 //
  15 //      You should have received a copy of the GNU General Public License
  16 //      along with SCSI2SD.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 #include "scsi.h"
  19 #include "scsiPhy.h"
  20 #include "config.h"
  21 #include "diagnostic.h"
  22 #include "disk.h"
  23 #include "inquiry.h"
  24 #include "led.h"
  25 #include "mode.h"
  26 #include "time.h"
  27 #include "bsp.h"
  28 #include "cdrom.h"
  29 //#include "debug.h"
  30 #include "tape.h"
  31 #include "mo.h"
  32
  33 #include <string.h>
  34
  35 // Global SCSI device state.
  36 ScsiDevice scsiDev S2S_DMA_ALIGN;
  37
  38 static void enter_SelectionPhase(void);
  39 static void process_SelectionPhase(void);
  40 static void enter_BusFree(void);
  41 static void enter_MessageIn(uint8_t message);
  42 static void enter_Status(uint8_t status);
  43 static void enter_DataIn(int len);
  44 static void process_DataIn(void);
  45 static void process_DataOut(void);
  46 static void process_Command(void);
  47
  48 static void doReserveRelease(void);
  49
  50 static void enter_BusFree()
  51 {
  52         // This delay probably isn't needed for most SCSI hosts, but it won't
  53         // hurt either. It's possible some of the samplers needed this delay.
  54         if (scsiDev.compatMode < COMPAT_SCSI2)
  55         {
  56                 s2s_delay_us(2);
  57         }
  58
  59 #if 0
  60         if (scsiDev.status != GOOD && isDebugEnabled())
  61         {
  62                 // We want to capture debug information for failure cases.
  63                 s2s_delay_ms(64);
  64         }
  65 #endif
  66
  67         scsiEnterBusFree();
  68
  69         // Wait for the initiator to cease driving signals
  70         // Bus settle delay + bus clear delay = 1200ns
  71         s2s_delay_us(2);
  72
  73
  74         s2s_ledOff();
  75         scsiDev.phase = BUS_FREE;
  76 }
  77
  78 static void enter_MessageIn(uint8_t message)
  79 {
  80         scsiDev.msgIn = message;
  81         scsiDev.phase = MESSAGE_IN;
  82 }
  83
  84 void process_MessageIn()
  85 {
  86         scsiEnterPhase(MESSAGE_IN);
  87         scsiWriteByte(scsiDev.msgIn);
  88
  89         if (unlikely(scsiDev.atnFlag))
  90         {
  91                 // If there was a parity error, we go
  92                 // back to MESSAGE_OUT first, get out parity error message, then come
  93                 // back here.
  94         }
  95         else if ((scsiDev.msgIn == MSG_LINKED_COMMAND_COMPLETE) ||
  96                 (scsiDev.msgIn == MSG_LINKED_COMMAND_COMPLETE_WITH_FLAG))
  97         {
  98                 // Go back to the command phase and start again.
  99                 scsiDev.phase = COMMAND;
 100                 scsiDev.parityError = 0;
 101                 scsiDev.dataPtr = 0;
 102                 scsiDev.savedDataPtr = 0;
 103                 scsiDev.dataLen = 0;
 104                 scsiDev.status = GOOD;
 105                 transfer.blocks = 0;
 106                 transfer.currentBlock = 0;
 107         }
 108         else /*if (scsiDev.msgIn == MSG_COMMAND_COMPLETE)*/
 109         {
 110                 enter_BusFree();
 111         }
 112 }
 113
 114 static void messageReject()
 115 {
 116         scsiEnterPhase(MESSAGE_IN);
 117         scsiWriteByte(MSG_REJECT);
 118 }
 119
 120 static void enter_Status(uint8_t status)
 121 {
 122         scsiDev.status = status;
 123         scsiDev.phase = STATUS;
 124
 125         scsiDev.lastStatus = scsiDev.status;
 126         scsiDev.lastSense = scsiDev.target->sense.code;
 127         scsiDev.lastSenseASC = scsiDev.target->sense.asc;
 128 }
 129
 130 void process_Status()
 131 {
 132         scsiEnterPhase(STATUS);
 133
 134         uint8_t message;
 135
 136         uint8_t control = scsiDev.cdb[scsiDev.cdbLen - 1];
 137         if ((scsiDev.status == GOOD) && (control & 0x01))
 138         {
 139                 // Linked command.
 140                 scsiDev.status = INTERMEDIATE;
 141                 if (control & 0x02)
 142                 {
 143                         message = MSG_LINKED_COMMAND_COMPLETE_WITH_FLAG;
 144                 }
 145                 else
 146                 {
 147                         message = MSG_LINKED_COMMAND_COMPLETE;
 148                 }
 149         }
 150         else
 151         {
 152                 message = MSG_COMMAND_COMPLETE;
 153         }
 154         scsiWriteByte(scsiDev.status);
 155
 156         scsiDev.lastStatus = scsiDev.status;
 157         scsiDev.lastSense = scsiDev.target->sense.code;
 158         scsiDev.lastSenseASC = scsiDev.target->sense.asc;
 159
 160         // Command Complete occurs AFTER a valid status has been
 161         // sent. then we go bus-free.
 162         enter_MessageIn(message);
 163 }
 164
 165 static void enter_DataIn(int len)
 166 {
 167         scsiDev.dataLen = len;
 168         scsiDev.phase = DATA_IN;
 169 }
 170
 171 static void process_DataIn()
 172 {
 173         uint32_t len;
 174
 175         if (scsiDev.dataLen > sizeof(scsiDev.data))
 176         {
 177                 scsiDev.dataLen = sizeof(scsiDev.data);
 178         }
 179
 180         len = scsiDev.dataLen - scsiDev.dataPtr;
 181         if (len > 0)
 182         {
 183                 scsiEnterPhase(DATA_IN);
 184                 scsiWrite(scsiDev.data + scsiDev.dataPtr, len);
 185                 scsiDev.dataPtr += len;
 186         }
 187
 188         if ((scsiDev.dataPtr >= scsiDev.dataLen) &&
 189                 (transfer.currentBlock == transfer.blocks))
 190         {
 191                 enter_Status(GOOD);
 192         }
 193 }
 194
 195 static void process_DataOut()
 196 {
 197         uint32_t len;
 198
 199         if (scsiDev.dataLen > sizeof(scsiDev.data))
 200         {
 201                 scsiDev.dataLen = sizeof(scsiDev.data);
 202         }
 203
 204         scsiDev.parityError = 0;
 205         len = scsiDev.dataLen - scsiDev.dataPtr;
 206         if (len > 0)
 207         {
 208                 scsiEnterPhase(DATA_OUT);
 209
 210                 scsiRead(scsiDev.data + scsiDev.dataPtr, len);
 211                 scsiDev.dataPtr += len;
 212
 213                 if (scsiDev.parityError &&
 214                         (scsiDev.boardCfg.flags & S2S_CFG_ENABLE_PARITY) &&
 215                         (scsiDev.compatMode >= COMPAT_SCSI2))
 216                 {
 217                         scsiDev.target->sense.code = ABORTED_COMMAND;
 218                         scsiDev.target->sense.asc = SCSI_PARITY_ERROR;
 219                         enter_Status(CHECK_CONDITION);
 220                 }
 221         }
 222
 223         if ((scsiDev.dataPtr >= scsiDev.dataLen) &&
 224                 (transfer.currentBlock == transfer.blocks))
 225         {
 226                 if (scsiDev.postDataOutHook != NULL)
 227                 {
 228                         scsiDev.postDataOutHook();
 229                 }
 230                 else
 231                 {
 232                         enter_Status(GOOD);
 233                 }
 234         }
 235 }
 236
 237 static const uint8_t CmdGroupBytes[8] = {6, 10, 10, 6, 6, 12, 6, 6};
 238 static void process_Command()
 239 {
 240         int group;
 241         uint8_t command;
 242         uint8_t control;
 243
 244         scsiEnterPhase(COMMAND);
 245         scsiDev.parityError = 0;
 246
 247         memset(scsiDev.cdb + 6, 0, sizeof(scsiDev.cdb) - 6);
 248         scsiRead(scsiDev.cdb, 6);
 249
 250         group = scsiDev.cdb[0] >> 5;
 251         scsiDev.cdbLen = CmdGroupBytes[group];
 252         if (scsiDev.cdbLen - 6 > 0)
 253         {
 254                 scsiRead(scsiDev.cdb + 6, scsiDev.cdbLen - 6);
 255         }
 256
 257         command = scsiDev.cdb[0];
 258
 259         // Prefer LUN's set by IDENTIFY messages for newer hosts.
 260         if (scsiDev.lun < 0)
 261         {
 262                 scsiDev.lun = scsiDev.cdb[1] >> 5;
 263         }
 264
 265         control = scsiDev.cdb[scsiDev.cdbLen - 1];
 266
 267         scsiDev.cmdCount++;
 268         const S2S_TargetCfg* cfg = scsiDev.target->cfg;
 269
 270         if (unlikely(scsiDev.resetFlag))
 271         {
 272                 // Don't log bogus commands
 273                 scsiDev.cmdCount--;
 274                 memset(scsiDev.cdb, 0xff, sizeof(scsiDev.cdb));
 275                 return;
 276         }
 277         else if (scsiDev.parityError &&
 278                 (scsiDev.boardCfg.flags & S2S_CFG_ENABLE_PARITY) &&
 279                 (scsiDev.compatMode >= COMPAT_SCSI2))
 280         {
 281                 scsiDev.target->sense.code = ABORTED_COMMAND;
 282                 scsiDev.target->sense.asc = SCSI_PARITY_ERROR;
 283                 enter_Status(CHECK_CONDITION);
 284         }
 285         else if ((control & 0x02) && ((control & 0x01) == 0))
 286         {
 287                 // FLAG set without LINK flag.
 288                 scsiDev.target->sense.code = ILLEGAL_REQUEST;
 289                 scsiDev.target->sense.asc = INVALID_FIELD_IN_CDB;
 290                 enter_Status(CHECK_CONDITION);
 291         }
 292         else if (command == 0x12)
 293         {
 294                 s2s_scsiInquiry();
 295         }
 296         else if (command == 0x03)
 297         {
 298                 // REQUEST SENSE
 299                 uint32_t allocLength = scsiDev.cdb[4];
 300
 301                 // As specified by the SASI and SCSI1 standard.
 302                 // Newer initiators won't be specifying 0 anyway.
 303                 if (allocLength == 0) allocLength = 4;
 304
 305                 memset(scsiDev.data, 0, 256); // Max possible alloc length
 306                 scsiDev.data[0] = 0xF0;
 307                 scsiDev.data[2] = scsiDev.target->sense.code & 0x0F;
 308
 309                 scsiDev.data[3] = transfer.lba >> 24;
 310                 scsiDev.data[4] = transfer.lba >> 16;
 311                 scsiDev.data[5] = transfer.lba >> 8;
 312                 scsiDev.data[6] = transfer.lba;
 313
 314                 // Additional bytes if there are errors to report
 315                 scsiDev.data[7] = 10; // additional length
 316                 scsiDev.data[12] = scsiDev.target->sense.asc >> 8;
 317                 scsiDev.data[13] = scsiDev.target->sense.asc;
 318
 319                 // Silently truncate results. SCSI-2 spec 8.2.14.
 320                 enter_DataIn(allocLength);
 321
 322                 // This is a good time to clear out old sense information.
 323                 scsiDev.target->sense.code = NO_SENSE;
 324                 scsiDev.target->sense.asc = NO_ADDITIONAL_SENSE_INFORMATION;
 325         }
 326         // Some old SCSI drivers do NOT properly support
 327         // unitAttention. eg. the Mac Plus would trigger a SCSI reset
 328         // on receiving the unit attention response on boot, thus
 329         // triggering another unit attention condition.
 330         else if (scsiDev.target->unitAttention &&
 331                 (scsiDev.boardCfg.flags & S2S_CFG_ENABLE_UNIT_ATTENTION))
 332         {
 333                 scsiDev.target->sense.code = UNIT_ATTENTION;
 334                 scsiDev.target->sense.asc = scsiDev.target->unitAttention;
 335
 336                 // If initiator doesn't do REQUEST SENSE for the next command, then
 337                 // data is lost.
 338                 scsiDev.target->unitAttention = 0;
 339
 340                 enter_Status(CHECK_CONDITION);
 341         }
 342         else if (scsiDev.lun)
 343         {
 344                 scsiDev.target->sense.code = ILLEGAL_REQUEST;
 345                 scsiDev.target->sense.asc = LOGICAL_UNIT_NOT_SUPPORTED;
 346                 enter_Status(CHECK_CONDITION);
 347         }
 348         else if (command == 0x17 || command == 0x16)
 349         {
 350                 doReserveRelease();
 351         }
 352         else if ((scsiDev.target->reservedId >= 0) &&
 353                 (scsiDev.target->reservedId != scsiDev.initiatorId))
 354         {
 355                 enter_Status(CONFLICT);
 356         }
 357         // Handle odd device types first that may override basic read and
 358         // write commands. Will fall-through to generic disk handling.
 359         else if (((cfg->deviceType == S2S_CFG_OPTICAL) && scsiCDRomCommand()) ||
 360                 ((cfg->deviceType == S2S_CFG_SEQUENTIAL) && scsiTapeCommand()) ||
 361                 ((cfg->deviceType == S2S_CFG_MO) && scsiMOCommand()))
 362         {
 363                 // Already handled.
 364         }
 365         else if (scsiDiskCommand())
 366         {
 367                 // Already handled.
 368                 // check for the performance-critical read/write
 369                 // commands ASAP.
 370         }
 371         else if (command == 0x1C)
 372         {
 373                 scsiReceiveDiagnostic();
 374         }
 375         else if (command == 0x1D)
 376         {
 377                 scsiSendDiagnostic();
 378         }
 379         else if (command == 0x3B)
 380         {
 381                 scsiWriteBuffer();
 382         }
 383         else if (command == 0x3C)
 384         {
 385                 scsiReadBuffer();
 386         }
 387         else if (!scsiModeCommand())
 388         {
 389                 scsiDev.target->sense.code = ILLEGAL_REQUEST;
 390                 scsiDev.target->sense.asc = INVALID_COMMAND_OPERATION_CODE;
 391                 enter_Status(CHECK_CONDITION);
 392         }
 393
 394         // Successful
 395         if (scsiDev.phase == COMMAND) // No status set, and not in DATA_IN
 396         {
 397                 enter_Status(GOOD);
 398         }
 399
 400 }
 401
 402 static void doReserveRelease()
 403 {
 404         int extentReservation = scsiDev.cdb[1] & 1;
 405         int thirdPty = scsiDev.cdb[1] & 0x10;
 406         int thirdPtyId = (scsiDev.cdb[1] >> 1) & 0x7;
 407         uint8_t command = scsiDev.cdb[0];
 408
 409         int canRelease =
 410                 (!thirdPty && (scsiDev.initiatorId == scsiDev.target->reservedId)) ||
 411                         (thirdPty &&
 412                                 (scsiDev.target->reserverId == scsiDev.initiatorId) &&
 413                                 (scsiDev.target->reservedId == thirdPtyId)
 414                         );
 415
 416         if (extentReservation)
 417         {
 418                 // Not supported.
 419                 scsiDev.target->sense.code = ILLEGAL_REQUEST;
 420                 scsiDev.target->sense.asc = INVALID_FIELD_IN_CDB;
 421                 enter_Status(CHECK_CONDITION);
 422         }
 423         else if (command == 0x17) // release
 424         {
 425                 if ((scsiDev.target->reservedId < 0) || canRelease)
 426                 {
 427                         scsiDev.target->reservedId = -1;
 428                         scsiDev.target->reserverId = -1;
 429                 }
 430                 else
 431                 {
 432                         enter_Status(CONFLICT);
 433                 }
 434         }
 435         else // assume reserve.
 436         {
 437                 if ((scsiDev.target->reservedId < 0) || canRelease)
 438                 {
 439                         scsiDev.target->reserverId = scsiDev.initiatorId;
 440                         if (thirdPty)
 441                         {
 442                                 scsiDev.target->reservedId = thirdPtyId;
 443                         }
 444                         else
 445                         {
 446                                 scsiDev.target->reservedId = scsiDev.initiatorId;
 447                         }
 448                 }
 449                 else
 450                 {
 451                         // Already reserved by someone else!
 452                         enter_Status(CONFLICT);
 453                 }
 454         }
 455 }
 456
 457 static void scsiReset()
 458 {
 459         scsiDev.rstCount++;
 460         s2s_ledOff();
 461
 462         scsiPhyReset();
 463
 464         scsiDev.parityError = 0;
 465         scsiDev.phase = BUS_FREE;
 466         scsiDev.atnFlag = 0;
 467         scsiDev.resetFlag = 0;
 468         scsiDev.lun = -1;
 469         scsiDev.compatMode = COMPAT_UNKNOWN;
 470
 471         if (scsiDev.target)
 472         {
 473                 if (scsiDev.target->unitAttention != POWER_ON_RESET)
 474                 {
 475                         scsiDev.target->unitAttention = SCSI_BUS_RESET;
 476                 }
 477                 scsiDev.target->reservedId = -1;
 478                 scsiDev.target->reserverId = -1;
 479                 scsiDev.target->sense.code = NO_SENSE;
 480                 scsiDev.target->sense.asc = NO_ADDITIONAL_SENSE_INFORMATION;
 481         }
 482         scsiDev.target = NULL;
 483         scsiDiskReset();
 484
 485         scsiDev.postDataOutHook = NULL;
 486
 487         // Sleep to allow the bus to settle down a bit.
 488         // We must be ready again within the "Reset to selection time" of
 489         // 250ms.
 490         // There is no guarantee that the RST line will be negated by then.
 491         // NOTE: We could be connected and powered by USB for configuration,
 492         // in which case TERMPWR cannot be supplied, and reset will ALWAYS
 493         // be true. Therefore, the sleep here must be slow to avoid slowing
 494         // USB comms
 495         s2s_delay_ms(1); // 1ms.
 496 }
 497
 498 static void enter_SelectionPhase()
 499 {
 500         // Ignore stale versions of this flag, but ensure we know the
 501         // current value if the flag is still set.
 502         scsiDev.atnFlag = 0;
 503         scsiDev.parityError = 0;
 504         scsiDev.dataPtr = 0;
 505         scsiDev.savedDataPtr = 0;
 506         scsiDev.dataLen = 0;
 507         scsiDev.status = GOOD;
 508         scsiDev.phase = SELECTION;
 509         scsiDev.lun = -1;
 510         scsiDev.discPriv = 0;
 511
 512         scsiDev.initiatorId = -1;
 513         scsiDev.target = NULL;
 514
 515         transfer.blocks = 0;
 516         transfer.currentBlock = 0;
 517
 518         scsiDev.postDataOutHook = NULL;
 519 }
 520
 521 static void process_SelectionPhase()
 522 {
 523         // Selection delays.
 524         // Many SCSI1 samplers that use a 5380 chip need a delay of at least 1ms.
 525         // The Mac Plus boot-time (ie. rom code) selection abort time
 526         // is < 1ms and must have no delay (standard suggests 250ms abort time)
 527         // Most newer SCSI2 hosts don't care either way.
 528         if (scsiDev.boardCfg.selectionDelay == 255) // auto
 529         {
 530                 if (scsiDev.compatMode < COMPAT_SCSI2)
 531                 {
 532                         s2s_delay_ms(1);
 533                 }
 534         }
 535         else if (scsiDev.boardCfg.selectionDelay != 0)
 536         {
 537                 s2s_delay_ms(scsiDev.boardCfg.selectionDelay);
 538         }
 539
 540         uint8_t selStatus = *SCSI_STS_SELECTED;
 541
 542         int tgtIndex;
 543         TargetState* target = NULL;
 544         for (tgtIndex = 0; tgtIndex < S2S_MAX_TARGETS; ++tgtIndex)
 545         {
 546                 if (scsiDev.targets[tgtIndex].targetId == (selStatus & 7))
 547                 {
 548                         target = &scsiDev.targets[tgtIndex];
 549                         break;
 550                 }
 551         }
 552         if ((target != NULL) && (selStatus & 0x40))
 553 // TODO         (goodParity || !(scsiDev.boardCfg.flags & S2S_CFG_ENABLE_PARITY) || !atnFlag)
 554         {
 555                 // We've been selected!
 556                 // Assert BSY - Selection success!
 557                 // must happen within 200us (Selection abort time) of seeing our
 558                 // ID + SEL.
 559                 // (Note: the initiator will be waiting the "Selection time-out delay"
 560                 // for our BSY response, which is actually a very generous 250ms)
 561                 *SCSI_CTRL_BSY = 1;
 562                 s2s_ledOn();
 563
 564                 scsiDev.target = target;
 565
 566                 // Do we enter MESSAGE OUT immediately ? SCSI 1 and 2 standards says
 567                 // move to MESSAGE OUT if ATN is true before we assert BSY.
 568                 // The initiator should assert ATN with SEL.
 569                 scsiDev.atnFlag = selStatus & 0x80;
 570
 571
 572                 // Unit attention breaks many older SCSI hosts. Disable it completely
 573                 // for SCSI-1 (and older) hosts, regardless of our configured setting.
 574                 // Enable the compatability mode also as many SASI and SCSI1
 575                 // controllers don't generate parity bits.
 576                 if (!scsiDev.atnFlag)
 577                 {
 578                         target->unitAttention = 0;
 579                         scsiDev.compatMode = COMPAT_SCSI1;
 580                 }
 581                 else if (!(scsiDev.boardCfg.flags & S2S_CFG_ENABLE_SCSI2))
 582                 {
 583                         scsiDev.compatMode = COMPAT_SCSI1;
 584                 }
 585                 else if (scsiDev.compatMode == COMPAT_UNKNOWN)
 586                 {
 587                         scsiDev.compatMode = COMPAT_SCSI2;
 588                 }
 589
 590                 scsiDev.selCount++;
 591
 592
 593                 // Save our initiator now that we're no longer in a time-critical
 594                 // section.
 595                 // SCSI1/SASI initiators may not set their own ID.
 596                 scsiDev.initiatorId = (selStatus >> 3) & 0x7;
 597
 598                 while (likely(!scsiDev.resetFlag) && scsiStatusSEL())
 599                 {
 600                         // Wait until the end of the selection phase.
 601                 }
 602
 603                 scsiDev.phase = COMMAND;
 604         }
 605         else if (!selStatus)
 606         {
 607                 scsiDev.phase = BUS_BUSY;
 608         }
 609 }
 610
 611 static void process_MessageOut()
 612 {
 613         scsiEnterPhase(MESSAGE_OUT);
 614
 615         scsiDev.atnFlag = 0;
 616         scsiDev.parityError = 0;
 617         scsiDev.msgOut = scsiReadByte();
 618         scsiDev.msgCount++;
 619
 620         if (scsiDev.parityError &&
 621                 (scsiDev.boardCfg.flags & S2S_CFG_ENABLE_PARITY) &&
 622                 (scsiDev.compatMode >= COMPAT_SCSI2))
 623         {
 624                 // Skip the remaining message bytes, and then start the MESSAGE_OUT
 625                 // phase again from the start. The initiator will re-send the
 626                 // same set of messages.
 627                 while (scsiStatusATN() && !scsiDev.resetFlag)
 628                 {
 629                         scsiReadByte();
 630                 }
 631
 632                 // Go-back and try the message again.
 633                 scsiDev.atnFlag = 1;
 634                 scsiDev.parityError = 0;
 635         }
 636         else if (scsiDev.msgOut == 0x00)
 637         {
 638                 // COMMAND COMPLETE. but why would the target be receiving this ? nfi.
 639                 enter_BusFree();
 640         }
 641         else if (scsiDev.msgOut == 0x06)
 642         {
 643                 // ABORT
 644                 scsiDiskReset();
 645                 enter_BusFree();
 646         }
 647         else if (scsiDev.msgOut == 0x0C)
 648         {
 649                 // BUS DEVICE RESET
 650
 651                 scsiDiskReset();
 652
 653                 scsiDev.target->unitAttention = SCSI_BUS_RESET;
 654
 655                 // ANY initiator can reset the reservation state via this message.
 656                 scsiDev.target->reservedId = -1;
 657                 scsiDev.target->reserverId = -1;
 658                 enter_BusFree();
 659         }
 660         else if (scsiDev.msgOut == 0x05)
 661         {
 662                 // Initiate Detected Error
 663                 // Ignore for now
 664         }
 665         else if (scsiDev.msgOut == 0x0F)
 666         {
 667                 // INITIATE RECOVERY
 668                 // Ignore for now
 669         }
 670         else if (scsiDev.msgOut == 0x10)
 671         {
 672                 // RELEASE RECOVERY
 673                 // Ignore for now
 674                 enter_BusFree();
 675         }
 676         else if (scsiDev.msgOut == MSG_REJECT)
 677         {
 678                 // Message Reject
 679                 // Oh well.
 680                 scsiDev.resetFlag = 1;
 681         }
 682         else if (scsiDev.msgOut == 0x08)
 683         {
 684                 // NOP
 685         }
 686         else if (scsiDev.msgOut == 0x09)
 687         {
 688                 // Message Parity Error
 689                 // Go back and re-send the last message.
 690                 scsiDev.phase = MESSAGE_IN;
 691         }
 692         else if (scsiDev.msgOut & 0x80) // 0x80 -> 0xFF
 693         {
 694                 // IDENTIFY
 695                 if ((scsiDev.msgOut & 0x18) || // Reserved bits set.
 696                         (scsiDev.msgOut & 0x20))  // We don't have any target routines!
 697                 {
 698                         messageReject();
 699                 }
 700
 701                 scsiDev.lun = scsiDev.msgOut & 0x7;
 702                 scsiDev.discPriv =
 703                         ((scsiDev.msgOut & 0x40) && (scsiDev.initiatorId >= 0))
 704                                 ? 1 : 0;
 705         }
 706         else if (scsiDev.msgOut >= 0x20 && scsiDev.msgOut <= 0x2F)
 707         {
 708                 // Two byte message. We don't support these. read and discard.
 709                 scsiReadByte();
 710
 711                 if (scsiDev.msgOut == 0x23) {
 712                         // Ignore Wide Residue. We're only 8 bit anyway.
 713                 } else {
 714                         messageReject();
 715                 }
 716         }
 717         else if (scsiDev.msgOut == 0x01)
 718         {
 719                 int i;
 720
 721                 // Extended message.
 722                 int msgLen = scsiReadByte();
 723                 if (msgLen == 0) msgLen = 256;
 724                 uint8_t extmsg[256];
 725                 for (i = 0; i < msgLen && !scsiDev.resetFlag; ++i)
 726                 {
 727                         // Discard bytes.
 728                         extmsg[i] = scsiReadByte();
 729                 }
 730
 731                 if (extmsg[0] == 3 && msgLen == 2) // Wide Data Request
 732                 {
 733                         // Negotiate down to 8bit
 734                         scsiEnterPhase(MESSAGE_IN);
 735                         static const uint8_t WDTR[] = {0x01, 0x02, 0x03, 0x00};
 736                         scsiWrite(WDTR, sizeof(WDTR));
 737                 }
 738                 else if (extmsg[0] == 1 && msgLen == 3) // Synchronous data request
 739                 {
 740                         // Negotiate back to async
 741                         scsiEnterPhase(MESSAGE_IN);
 742                         static const uint8_t SDTR[] = {0x01, 0x03, 0x01, 0x00, 0x00};
 743                         scsiWrite(SDTR, sizeof(SDTR));
 744                 }
 745                 else
 746                 {
 747                         // Not supported
 748                         messageReject();
 749                 }
 750         }
 751         else
 752         {
 753                 messageReject();
 754         }
 755
 756         // Re-check the ATN flag in case it stays asserted.
 757         scsiDev.atnFlag |= scsiStatusATN();
 758 }
 759
 760 void scsiPoll(void)
 761 {
 762         if (unlikely(scsiDev.resetFlag))
 763         {
 764                 scsiReset();
 765                 if ((scsiDev.resetFlag = scsiStatusRST()))
 766                 {
 767                         // Still in reset phase. Do not try and process any commands.
 768                         return;
 769                 }
 770         }
 771
 772         switch (scsiDev.phase)
 773         {
 774         case BUS_FREE:
 775                 if (scsiStatusBSY())
 776                 {
 777                         scsiDev.phase = BUS_BUSY;
 778                 }
 779                 // The Arbitration phase is optional for SCSI1/SASI hosts if there is only
 780                 // one initiator in the chain. Support this by moving
 781                 // straight to selection if SEL is asserted.
 782                 // ie. the initiator won't assert BSY and it's own ID before moving to selection.
 783                 else if (*SCSI_STS_SELECTED)
 784                 {
 785                         enter_SelectionPhase();
 786                 }
 787         break;
 788
 789         case BUS_BUSY:
 790                 // Someone is using the bus. Perhaps they are trying to
 791                 // select us.
 792                 if (*SCSI_STS_SELECTED)
 793                 {
 794                         enter_SelectionPhase();
 795                 }
 796                 else if (!scsiStatusBSY())
 797                 {
 798                         scsiDev.phase = BUS_FREE;
 799                 }
 800         break;
 801
 802         case ARBITRATION:
 803                 // TODO Support reselection.
 804                 break;
 805
 806         case SELECTION:
 807                 process_SelectionPhase();
 808         break;
 809
 810         case RESELECTION:
 811                 // Not currently supported!
 812         break;
 813
 814         case COMMAND:
 815                 // Do not check ATN here. SCSI 1 & 2 initiators must set ATN
 816                 // and SEL together upon entering the selection phase if they
 817                 // want to send a message (IDENTIFY) immediately.
 818                 if (scsiDev.atnFlag)
 819                 {
 820                         process_MessageOut();
 821                 }
 822                 else
 823                 {
 824                         process_Command();
 825                 }
 826         break;
 827
 828         case DATA_IN:
 829                 scsiDev.atnFlag |= scsiStatusATN();
 830                 if (scsiDev.atnFlag)
 831                 {
 832                         process_MessageOut();
 833                 }
 834                 else
 835                 {
 836                         process_DataIn();
 837                 }
 838         break;
 839
 840         case DATA_OUT:
 841                 scsiDev.atnFlag |= scsiStatusATN();
 842                 if (scsiDev.atnFlag)
 843                 {
 844                         process_MessageOut();
 845                 }
 846                 else
 847                 {
 848                         process_DataOut();
 849                 }
 850         break;
 851
 852         case STATUS:
 853                 scsiDev.atnFlag |= scsiStatusATN();
 854                 if (scsiDev.atnFlag)
 855                 {
 856                         process_MessageOut();
 857                 }
 858                 else
 859                 {
 860                         process_Status();
 861                 }
 862         break;
 863
 864         case MESSAGE_IN:
 865                 scsiDev.atnFlag |= scsiStatusATN();
 866                 if (scsiDev.atnFlag)
 867                 {
 868                         process_MessageOut();
 869                 }
 870                 else
 871                 {
 872                         process_MessageIn();
 873                 }
 874
 875         break;
 876
 877         case MESSAGE_OUT:
 878                 process_MessageOut();
 879         break;
 880         }
 881 }
 882
 883 void scsiInit()
 884 {
 885         static int firstInit = 1;
 886
 887         scsiDev.atnFlag = 0;
 888         scsiDev.resetFlag = 1;
 889         scsiDev.phase = BUS_FREE;
 890         scsiDev.target = NULL;
 891         scsiDev.compatMode = COMPAT_UNKNOWN;
 892
 893         int i;
 894         for (i = 0; i < S2S_MAX_TARGETS; ++i)
 895         {
 896                 const S2S_TargetCfg* cfg = s2s_getConfigByIndex(i);
 897                 if (cfg && (cfg->scsiId & S2S_CFG_TARGET_ENABLED))
 898                 {
 899                         scsiDev.targets[i].targetId = cfg->scsiId & S2S_CFG_TARGET_ID_BITS;
 900                         scsiDev.targets[i].cfg = cfg;
 901
 902                         scsiDev.targets[i].liveCfg.bytesPerSector = cfg->bytesPerSector;
 903                 }
 904                 else
 905                 {
 906                         scsiDev.targets[i].targetId = 0xff;
 907                         scsiDev.targets[i].cfg = NULL;
 908                 }
 909                 scsiDev.targets[i].reservedId = -1;
 910                 scsiDev.targets[i].reserverId = -1;
 911                 if (firstInit)
 912                 {
 913                         scsiDev.targets[i].unitAttention = POWER_ON_RESET;
 914                 }
 915                 else
 916                 {
 917                         scsiDev.targets[i].unitAttention = PARAMETERS_CHANGED;
 918                 }
 919                 scsiDev.targets[i].sense.code = NO_SENSE;
 920                 scsiDev.targets[i].sense.asc = NO_ADDITIONAL_SENSE_INFORMATION;
 921         }
 922         firstInit = 0;
 923 }
 924
 925 /* TODO REENABLE
 926 void scsiDisconnect()
 927 {
 928         scsiEnterPhase(MESSAGE_IN);
 929         scsiWriteByte(0x02); // save data pointer
 930         scsiWriteByte(0x04); // disconnect msg.
 931
 932         // For now, the caller is responsible for tracking the disconnected
 933         // state, and calling scsiReconnect.
 934         // Ideally the client would exit their loop and we'd implement this
 935         // as part of scsiPoll
 936         int phase = scsiDev.phase;
 937         enter_BusFree();
 938         scsiDev.phase = phase;
 939 }
 940 */
 941
 942 /* TODO REENABLE
 943 int scsiReconnect()
 944 {
 945         int reconnected = 0;
 946
 947         int sel = SCSI_ReadFilt(SCSI_Filt_SEL);
 948         int bsy = SCSI_ReadFilt(SCSI_Filt_BSY);
 949         if (!sel && !bsy)
 950         {
 951                 s2s_delay_us(1);
 952                 sel = SCSI_ReadFilt(SCSI_Filt_SEL);
 953                 bsy = SCSI_ReadFilt(SCSI_Filt_BSY);
 954         }
 955
 956         if (!sel && !bsy)
 957         {
 958                 // Arbitrate.
 959                 s2s_ledOn();
 960                 uint8_t scsiIdMask = 1 << scsiDev.target->targetId;
 961                 SCSI_Out_Bits_Write(scsiIdMask);
 962                 SCSI_Out_Ctl_Write(1); // Write bits manually.
 963                 SCSI_SetPin(SCSI_Out_BSY);
 964
 965                 s2s_delay_us(3); // arbitrate delay. 2.4us.
 966
 967                 uint8_t dbx = scsiReadDBxPins();
 968                 sel = SCSI_ReadFilt(SCSI_Filt_SEL);
 969                 if (sel || ((dbx ^ scsiIdMask) > scsiIdMask))
 970                 {
 971                         // Lost arbitration.
 972                         SCSI_Out_Ctl_Write(0);
 973                         SCSI_ClearPin(SCSI_Out_BSY);
 974                         s2s_ledOff();
 975                 }
 976                 else
 977                 {
 978                         // Won arbitration
 979                         SCSI_SetPin(SCSI_Out_SEL);
 980                         s2s_delay_us(1); // Bus clear + Bus settle.
 981
 982                         // Reselection phase
 983                         SCSI_CTL_PHASE_Write(__scsiphase_io);
 984                         SCSI_Out_Bits_Write(scsiIdMask | (1 << scsiDev.initiatorId));
 985                         scsiDeskewDelay(); // 2 deskew delays
 986                         scsiDeskewDelay(); // 2 deskew delays
 987                         SCSI_ClearPin(SCSI_Out_BSY);
 988                         s2s_delay_us(1);  // Bus Settle Delay
 989
 990                         uint32_t waitStart_ms = getTime_ms();
 991                         bsy = SCSI_ReadFilt(SCSI_Filt_BSY);
 992                         // Wait for initiator.
 993                         while (
 994                                 !bsy &&
 995                                 !scsiDev.resetFlag &&
 996                                 (elapsedTime_ms(waitStart_ms) < 250))
 997                         {
 998                                 bsy = SCSI_ReadFilt(SCSI_Filt_BSY);
 999                         }
1000
1001                         if (bsy)
1002                         {
1003                                 SCSI_SetPin(SCSI_Out_BSY);
1004                                 scsiDeskewDelay(); // 2 deskew delays
1005                                 scsiDeskewDelay(); // 2 deskew delays
1006                                 SCSI_ClearPin(SCSI_Out_SEL);
1007
1008                                 // Prepare for the initial IDENTIFY message.
1009                                 SCSI_Out_Ctl_Write(0);
1010                                 scsiEnterPhase(MESSAGE_IN);
1011
1012                                 // Send identify command
1013                                 scsiWriteByte(0x80);
1014
1015                                 scsiEnterPhase(scsiDev.phase);
1016                                 reconnected = 1;
1017                         }
1018                         else
1019                         {
1020                                 // reselect timeout.
1021                                 SCSI_Out_Ctl_Write(0);
1022                                 SCSI_ClearPin(SCSI_Out_SEL);
1023                                 SCSI_CTL_PHASE_Write(0);
1024                                 s2s_ledOff();
1025                         }
1026                 }
1027         }
1028         return reconnected;
1029 }
1030 */
1031