arch/m68k/mac/via.c

   1 /*
   2  *      6522 Versatile Interface Adapter (VIA)
   3  *
   4  *      There are two of these on the Mac II. Some IRQs are vectored
   5  *      via them as are assorted bits and bobs - eg RTC, ADB.
   6  *
   7  * CSA: Motorola seems to have removed documentation on the 6522 from
   8  * their web site; try
   9  *     http://nerini.drf.com/vectrex/other/text/chips/6522/
  10  *     http://www.zymurgy.net/classic/vic20/vicdet1.htm
  11  * and
  12  *     http://193.23.168.87/mikro_laborversuche/via_iobaustein/via6522_1.html
  13  * for info.  A full-text web search on 6522 AND VIA will probably also
  14  * net some usefulness. <cananian@alumni.princeton.edu> 20apr1999
  15  *
  16  * Additional data is here (the SY6522 was used in the Mac II etc):
  17  *     http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf
  18  *     http://www.6502.org/documents/datasheets/synertek/synertek_sy6522_programming_reference.pdf
  19  *
  20  * PRAM/RTC access algorithms are from the NetBSD RTC toolkit version 1.08b
  21  * by Erik Vogan and adapted to Linux by Joshua M. Thompson (funaho@jurai.org)
  22  *
  23  */
  24
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/mm.h>
  28 #include <linux/delay.h>
  29 #include <linux/init.h>
  30 #include <linux/module.h>
  31
  32 #include <asm/bootinfo.h>
  33 #include <asm/macintosh.h>
  34 #include <asm/macints.h>
  35 #include <asm/machw.h>
  36 #include <asm/mac_via.h>
  37 #include <asm/mac_psc.h>
  38
  39 volatile __u8 *via1, *via2;
  40 #if 0
  41 /* See note in mac_via.h about how this is possibly not useful */
  42 volatile long *via_memory_bogon=(long *)&via_memory_bogon;
  43 #endif
  44 int rbv_present;
  45 int via_alt_mapping;
  46 EXPORT_SYMBOL(via_alt_mapping);
  47 static __u8 rbv_clear;
  48
  49 /*
  50  * Globals for accessing the VIA chip registers without having to
  51  * check if we're hitting a real VIA or an RBV. Normally you could
  52  * just hit the combined register (ie, vIER|rIER) but that seems to
  53  * break on AV Macs...probably because they actually decode more than
  54  * eight address bits. Why can't Apple engineers at least be
  55  * _consistently_ lazy?                          - 1999-05-21 (jmt)
  56  */
  57
  58 static int gIER,gIFR,gBufA,gBufB;
  59
  60 /*
  61  * Timer defs.
  62  */
  63
  64 #define TICK_SIZE               10000
  65 #define MAC_CLOCK_TICK          (783300/HZ)             /* ticks per HZ */
  66 #define MAC_CLOCK_LOW           (MAC_CLOCK_TICK&0xFF)
  67 #define MAC_CLOCK_HIGH          (MAC_CLOCK_TICK>>8)
  68
  69 /* To disable a NuBus slot on Quadras we make the slot IRQ lines outputs, set
  70  * high. On RBV we just use the slot interrupt enable register. On Macs with
  71  * genuine VIA chips we must use nubus_disabled to keep track of disabled slot
  72  * interrupts. When any slot IRQ is disabled we mask the (edge triggered) CA1
  73  * or "SLOTS" interrupt. When no slot is disabled, we unmask the CA1 interrupt.
  74  * So, on genuine VIAs, having more than one NuBus IRQ can mean trouble,
  75  * because closing one of those drivers can mask all of the NuBus interrupts.
  76  * Also, since we can't mask the unregistered slot IRQs on genuine VIAs, it's
  77  * possible to get interrupts from cards that MacOS or the ROM has configured
  78  * but we have not. FWIW, "Designing Cards and Drivers for Macintosh II and
  79  * Macintosh SE", page 9-8, says, a slot IRQ with no driver would crash MacOS.
  80  */
  81 static u8 nubus_disabled;
  82
  83 void via_debug_dump(void);
  84 irqreturn_t via1_irq(int, void *);
  85 irqreturn_t via2_irq(int, void *);
  86 irqreturn_t via_nubus_irq(int, void *);
  87 void via_irq_enable(int irq);
  88 void via_irq_disable(int irq);
  89 void via_irq_clear(int irq);
  90
  91 extern irqreturn_t mac_scc_dispatch(int, void *);
  92 extern int oss_present;
  93
  94 /*
  95  * Initialize the VIAs
  96  *
  97  * First we figure out where they actually _are_ as well as what type of
  98  * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
  99  * Then we pretty much clear them out and disable all IRQ sources.
 100  *
 101  * Note: the OSS is actually "detected" here and not in oss_init(). It just
 102  *       seems more logical to do it here since via_init() needs to know
 103  *       these things anyways.
 104  */
 105
 106 void __init via_init(void)
 107 {
 108         switch(macintosh_config->via_type) {
 109
 110                 /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
 111
 112                 case MAC_VIA_IIci:
 113                         via1 = (void *) VIA1_BASE;
 114                         if (macintosh_config->ident == MAC_MODEL_IIFX) {
 115                                 via2 = NULL;
 116                                 rbv_present = 0;
 117                                 oss_present = 1;
 118                         } else {
 119                                 via2 = (void *) RBV_BASE;
 120                                 rbv_present = 1;
 121                                 oss_present = 0;
 122                         }
 123                         if (macintosh_config->ident == MAC_MODEL_LCIII) {
 124                                 rbv_clear = 0x00;
 125                         } else {
 126                                 /* on most RBVs (& unlike the VIAs), you   */
 127                                 /* need to set bit 7 when you write to IFR */
 128                                 /* in order for your clear to occur.       */
 129                                 rbv_clear = 0x80;
 130                         }
 131                         gIER = rIER;
 132                         gIFR = rIFR;
 133                         gBufA = rSIFR;
 134                         gBufB = rBufB;
 135                         break;
 136
 137                 /* Quadra and early MacIIs agree on the VIA locations */
 138
 139                 case MAC_VIA_QUADRA:
 140                 case MAC_VIA_II:
 141                         via1 = (void *) VIA1_BASE;
 142                         via2 = (void *) VIA2_BASE;
 143                         rbv_present = 0;
 144                         oss_present = 0;
 145                         rbv_clear = 0x00;
 146                         gIER = vIER;
 147                         gIFR = vIFR;
 148                         gBufA = vBufA;
 149                         gBufB = vBufB;
 150                         break;
 151                 default:
 152                         panic("UNKNOWN VIA TYPE");
 153         }
 154
 155         printk(KERN_INFO "VIA1 at %p is a 6522 or clone\n", via1);
 156
 157         printk(KERN_INFO "VIA2 at %p is ", via2);
 158         if (rbv_present) {
 159                 printk("an RBV\n");
 160         } else if (oss_present) {
 161                 printk("an OSS\n");
 162         } else {
 163                 printk("a 6522 or clone\n");
 164         }
 165
 166 #ifdef DEBUG_VIA
 167         via_debug_dump();
 168 #endif
 169
 170         /*
 171          * Shut down all IRQ sources, reset the timers, and
 172          * kill the timer latch on VIA1.
 173          */
 174
 175         via1[vIER] = 0x7F;
 176         via1[vIFR] = 0x7F;
 177         via1[vT1LL] = 0;
 178         via1[vT1LH] = 0;
 179         via1[vT1CL] = 0;
 180         via1[vT1CH] = 0;
 181         via1[vT2CL] = 0;
 182         via1[vT2CH] = 0;
 183         via1[vACR] &= 0x3F;
 184         via1[vACR] &= ~0x03; /* disable port A & B latches */
 185
 186         /*
 187          * SE/30: disable video IRQ
 188          * XXX: testing for SE/30 VBL
 189          */
 190
 191         if (macintosh_config->ident == MAC_MODEL_SE30) {
 192                 via1[vDirB] |= 0x40;
 193                 via1[vBufB] |= 0x40;
 194         }
 195
 196         /*
 197          * Set the RTC bits to a known state: all lines to outputs and
 198          * RTC disabled (yes that's 0 to enable and 1 to disable).
 199          */
 200
 201         via1[vDirB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData);
 202         via1[vBufB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk);
 203
 204         /* Everything below this point is VIA2/RBV only... */
 205
 206         if (oss_present) return;
 207
 208 #if 1
 209         /* Some machines support an alternate IRQ mapping that spreads  */
 210         /* Ethernet and Sound out to their own autolevel IRQs and moves */
 211         /* VIA1 to level 6. A/UX uses this mapping and we do too.  Note */
 212         /* that the IIfx emulates this alternate mapping using the OSS. */
 213
 214         switch(macintosh_config->ident) {
 215                 case MAC_MODEL_P475:
 216                 case MAC_MODEL_P475F:
 217                 case MAC_MODEL_P575:
 218                 case MAC_MODEL_Q605:
 219                 case MAC_MODEL_Q605_ACC:
 220                 case MAC_MODEL_C610:
 221                 case MAC_MODEL_Q610:
 222                 case MAC_MODEL_Q630:
 223                 case MAC_MODEL_C650:
 224                 case MAC_MODEL_Q650:
 225                 case MAC_MODEL_Q700:
 226                 case MAC_MODEL_Q800:
 227                 case MAC_MODEL_Q900:
 228                 case MAC_MODEL_Q950:
 229                         via_alt_mapping = 1;
 230                         via1[vDirB] |= 0x40;
 231                         via1[vBufB] &= ~0x40;
 232                         break;
 233                 default:
 234                         via_alt_mapping = 0;
 235                         break;
 236         }
 237 #else
 238         via_alt_mapping = 0;
 239 #endif
 240
 241         /*
 242          * Now initialize VIA2. For RBV we just kill all interrupts;
 243          * for a regular VIA we also reset the timers and stuff.
 244          */
 245
 246         via2[gIER] = 0x7F;
 247         via2[gIFR] = 0x7F | rbv_clear;
 248         if (!rbv_present) {
 249                 via2[vT1LL] = 0;
 250                 via2[vT1LH] = 0;
 251                 via2[vT1CL] = 0;
 252                 via2[vT1CH] = 0;
 253                 via2[vT2CL] = 0;
 254                 via2[vT2CH] = 0;
 255                 via2[vACR] &= 0x3F;
 256                 via2[vACR] &= ~0x03; /* disable port A & B latches */
 257         }
 258
 259         /*
 260          * Set vPCR for SCSI interrupts (but not on RBV)
 261          */
 262         if (!rbv_present) {
 263                 if (macintosh_config->scsi_type == MAC_SCSI_OLD) {
 264                         /* CB2 (IRQ) indep. input, positive edge */
 265                         /* CA2 (DRQ) indep. input, positive edge */
 266                         via2[vPCR] = 0x66;
 267                 } else {
 268                         /* CB2 (IRQ) indep. input, negative edge */
 269                         /* CA2 (DRQ) indep. input, negative edge */
 270                         via2[vPCR] = 0x22;
 271                 }
 272         }
 273 }
 274
 275 /*
 276  * Start the 100 Hz clock
 277  */
 278
 279 void __init via_init_clock(irq_handler_t func)
 280 {
 281         via1[vACR] |= 0x40;
 282         via1[vT1LL] = MAC_CLOCK_LOW;
 283         via1[vT1LH] = MAC_CLOCK_HIGH;
 284         via1[vT1CL] = MAC_CLOCK_LOW;
 285         via1[vT1CH] = MAC_CLOCK_HIGH;
 286
 287         request_irq(IRQ_MAC_TIMER_1, func, IRQ_FLG_LOCK, "timer", func);
 288 }
 289
 290 /*
 291  * Register the interrupt dispatchers for VIA or RBV machines only.
 292  */
 293
 294 void __init via_register_interrupts(void)
 295 {
 296         if (via_alt_mapping) {
 297                 request_irq(IRQ_AUTO_1, via1_irq,
 298                                 IRQ_FLG_LOCK|IRQ_FLG_FAST, "software",
 299                                 (void *) via1);
 300                 request_irq(IRQ_AUTO_6, via1_irq,
 301                                 IRQ_FLG_LOCK|IRQ_FLG_FAST, "via1",
 302                                 (void *) via1);
 303         } else {
 304                 request_irq(IRQ_AUTO_1, via1_irq,
 305                                 IRQ_FLG_LOCK|IRQ_FLG_FAST, "via1",
 306                                 (void *) via1);
 307         }
 308         request_irq(IRQ_AUTO_2, via2_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
 309                         "via2", (void *) via2);
 310         if (!psc_present) {
 311                 request_irq(IRQ_AUTO_4, mac_scc_dispatch, IRQ_FLG_LOCK,
 312                                 "scc", mac_scc_dispatch);
 313         }
 314         request_irq(IRQ_MAC_NUBUS, via_nubus_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
 315                         "nubus", (void *) via2);
 316 }
 317
 318 /*
 319  * Debugging dump, used in various places to see what's going on.
 320  */
 321
 322 void via_debug_dump(void)
 323 {
 324         printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
 325                 (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
 326         printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
 327                 (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
 328         if (oss_present) {
 329                 printk(KERN_DEBUG "VIA2: <OSS>\n");
 330         } else if (rbv_present) {
 331                 printk(KERN_DEBUG "VIA2:  IFR = 0x%02X  IER = 0x%02X\n",
 332                         (uint) via2[rIFR], (uint) via2[rIER]);
 333                 printk(KERN_DEBUG "      SIFR = 0x%02X SIER = 0x%02X\n",
 334                         (uint) via2[rSIFR], (uint) via2[rSIER]);
 335         } else {
 336                 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
 337                         (uint) via2[vDirA], (uint) via2[vDirB],
 338                         (uint) via2[vACR]);
 339                 printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
 340                         (uint) via2[vPCR],
 341                         (uint) via2[vIFR], (uint) via2[vIER]);
 342         }
 343 }
 344
 345 /*
 346  * This is always executed with interrupts disabled.
 347  *
 348  * TBI: get time offset between scheduling timer ticks
 349  */
 350
 351 unsigned long mac_gettimeoffset (void)
 352 {
 353         unsigned long ticks, offset = 0;
 354
 355         /* read VIA1 timer 2 current value */
 356         ticks = via1[vT1CL] | (via1[vT1CH] << 8);
 357         /* The probability of underflow is less than 2% */
 358         if (ticks > MAC_CLOCK_TICK - MAC_CLOCK_TICK / 50)
 359                 /* Check for pending timer interrupt in VIA1 IFR */
 360                 if (via1[vIFR] & 0x40) offset = TICK_SIZE;
 361
 362         ticks = MAC_CLOCK_TICK - ticks;
 363         ticks = ticks * 10000L / MAC_CLOCK_TICK;
 364
 365         return ticks + offset;
 366 }
 367
 368 /*
 369  * Flush the L2 cache on Macs that have it by flipping
 370  * the system into 24-bit mode for an instant.
 371  */
 372
 373 void via_flush_cache(void)
 374 {
 375         via2[gBufB] &= ~VIA2B_vMode32;
 376         via2[gBufB] |= VIA2B_vMode32;
 377 }
 378
 379 /*
 380  * Return the status of the L2 cache on a IIci
 381  */
 382
 383 int via_get_cache_disable(void)
 384 {
 385         /* Safeguard against being called accidentally */
 386         if (!via2) {
 387                 printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
 388                 return 1;
 389         }
 390
 391         return (int) via2[gBufB] & VIA2B_vCDis;
 392 }
 393
 394 /*
 395  * Initialize VIA2 for Nubus access
 396  */
 397
 398 void __init via_nubus_init(void)
 399 {
 400         /* unlock nubus transactions */
 401
 402         if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
 403             (macintosh_config->adb_type != MAC_ADB_PB2)) {
 404                 /* set the line to be an output on non-RBV machines */
 405                 if (!rbv_present)
 406                         via2[vDirB] |= 0x02;
 407
 408                 /* this seems to be an ADB bit on PMU machines */
 409                 /* according to MkLinux.  -- jmt               */
 410                 via2[gBufB] |= 0x02;
 411         }
 412
 413         /* Disable all the slot interrupts (where possible). */
 414
 415         switch (macintosh_config->via_type) {
 416         case MAC_VIA_II:
 417                 /* Just make the port A lines inputs. */
 418                 switch(macintosh_config->ident) {
 419                 case MAC_MODEL_II:
 420                 case MAC_MODEL_IIX:
 421                 case MAC_MODEL_IICX:
 422                 case MAC_MODEL_SE30:
 423                         /* The top two bits are RAM size outputs. */
 424                         via2[vDirA] &= 0xC0;
 425                         break;
 426                 default:
 427                         via2[vDirA] &= 0x80;
 428                 }
 429                 break;
 430         case MAC_VIA_IIci:
 431                 /* RBV. Disable all the slot interrupts. SIER works like IER. */
 432                 via2[rSIER] = 0x7F;
 433                 break;
 434         case MAC_VIA_QUADRA:
 435                 /* Disable the inactive slot interrupts by making those lines outputs. */
 436                 if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
 437                     (macintosh_config->adb_type != MAC_ADB_PB2)) {
 438                         via2[vBufA] |= 0x7F;
 439                         via2[vDirA] |= 0x7F;
 440                 }
 441                 break;
 442         }
 443 }
 444
 445 /*
 446  * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
 447  * via6522.c :-), disable/pending masks added.
 448  */
 449
 450 irqreturn_t via1_irq(int irq, void *dev_id)
 451 {
 452         int irq_num;
 453         unsigned char irq_bit, events;
 454
 455         events = via1[vIFR] & via1[vIER] & 0x7F;
 456         if (!events)
 457                 return IRQ_NONE;
 458
 459         irq_num = VIA1_SOURCE_BASE;
 460         irq_bit = 1;
 461         do {
 462                 if (events & irq_bit) {
 463                         via1[vIFR] = irq_bit;
 464                         m68k_handle_int(irq_num);
 465                 }
 466                 ++irq_num;
 467                 irq_bit <<= 1;
 468         } while (events >= irq_bit);
 469
 470 #if 0 /* freakin' pmu is doing weird stuff */
 471         if (!oss_present) {
 472                 /* This (still) seems to be necessary to get IDE
 473                    working.  However, if you enable VBL interrupts,
 474                    you're screwed... */
 475                 /* FIXME: should we check the SLOTIRQ bit before
 476                    pulling this stunt? */
 477                 /* No, it won't be set. that's why we're doing this. */
 478                 via_irq_disable(IRQ_MAC_NUBUS);
 479                 via_irq_clear(IRQ_MAC_NUBUS);
 480                 m68k_handle_int(IRQ_MAC_NUBUS);
 481                 via_irq_enable(IRQ_MAC_NUBUS);
 482         }
 483 #endif
 484         return IRQ_HANDLED;
 485 }
 486
 487 irqreturn_t via2_irq(int irq, void *dev_id)
 488 {
 489         int irq_num;
 490         unsigned char irq_bit, events;
 491
 492         events = via2[gIFR] & via2[gIER] & 0x7F;
 493         if (!events)
 494                 return IRQ_NONE;
 495
 496         irq_num = VIA2_SOURCE_BASE;
 497         irq_bit = 1;
 498         do {
 499                 if (events & irq_bit) {
 500                         via2[gIFR] = irq_bit | rbv_clear;
 501                         m68k_handle_int(irq_num);
 502                 }
 503                 ++irq_num;
 504                 irq_bit <<= 1;
 505         } while (events >= irq_bit);
 506         return IRQ_HANDLED;
 507 }
 508
 509 /*
 510  * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
 511  * VIA2 dispatcher as a fast interrupt handler.
 512  */
 513
 514 irqreturn_t via_nubus_irq(int irq, void *dev_id)
 515 {
 516         int slot_irq;
 517         unsigned char slot_bit, events;
 518
 519         events = ~via2[gBufA] & 0x7F;
 520         if (rbv_present)
 521                 events &= via2[rSIER];
 522         else
 523                 events &= ~via2[vDirA];
 524         if (!events)
 525                 return IRQ_NONE;
 526
 527         do {
 528                 slot_irq = IRQ_NUBUS_F;
 529                 slot_bit = 0x40;
 530                 do {
 531                         if (events & slot_bit) {
 532                                 events &= ~slot_bit;
 533                                 m68k_handle_int(slot_irq);
 534                         }
 535                         --slot_irq;
 536                         slot_bit >>= 1;
 537                 } while (events);
 538
 539                 /* clear the CA1 interrupt and make certain there's no more. */
 540                 via2[gIFR] = 0x02 | rbv_clear;
 541                 events = ~via2[gBufA] & 0x7F;
 542                 if (rbv_present)
 543                         events &= via2[rSIER];
 544                 else
 545                         events &= ~via2[vDirA];
 546         } while (events);
 547         return IRQ_HANDLED;
 548 }
 549
 550 void via_irq_enable(int irq) {
 551         int irq_src     = IRQ_SRC(irq);
 552         int irq_idx     = IRQ_IDX(irq);
 553
 554 #ifdef DEBUG_IRQUSE
 555         printk(KERN_DEBUG "via_irq_enable(%d)\n", irq);
 556 #endif
 557
 558         if (irq_src == 1) {
 559                 via1[vIER] = IER_SET_BIT(irq_idx);
 560         } else if (irq_src == 2) {
 561                 if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
 562                         via2[gIER] = IER_SET_BIT(irq_idx);
 563         } else if (irq_src == 7) {
 564                 switch (macintosh_config->via_type) {
 565                 case MAC_VIA_II:
 566                         nubus_disabled &= ~(1 << irq_idx);
 567                         /* Enable the CA1 interrupt when no slot is disabled. */
 568                         if (!nubus_disabled)
 569                                 via2[gIER] = IER_SET_BIT(1);
 570                         break;
 571                 case MAC_VIA_IIci:
 572                         /* On RBV, enable the slot interrupt.
 573                          * SIER works like IER.
 574                          */
 575                         via2[rSIER] = IER_SET_BIT(irq_idx);
 576                         break;
 577                 case MAC_VIA_QUADRA:
 578                         /* Make the port A line an input to enable the slot irq.
 579                          * But not on PowerBooks, that's ADB.
 580                          */
 581                         if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
 582                             (macintosh_config->adb_type != MAC_ADB_PB2))
 583                                 via2[vDirA] &= ~(1 << irq_idx);
 584                         break;
 585                 }
 586         }
 587 }
 588
 589 void via_irq_disable(int irq) {
 590         int irq_src     = IRQ_SRC(irq);
 591         int irq_idx     = IRQ_IDX(irq);
 592
 593 #ifdef DEBUG_IRQUSE
 594         printk(KERN_DEBUG "via_irq_disable(%d)\n", irq);
 595 #endif
 596
 597         if (irq_src == 1) {
 598                 via1[vIER] = IER_CLR_BIT(irq_idx);
 599         } else if (irq_src == 2) {
 600                 via2[gIER] = IER_CLR_BIT(irq_idx);
 601         } else if (irq_src == 7) {
 602                 switch (macintosh_config->via_type) {
 603                 case MAC_VIA_II:
 604                         nubus_disabled |= 1 << irq_idx;
 605                         if (nubus_disabled)
 606                                 via2[gIER] = IER_CLR_BIT(1);
 607                         break;
 608                 case MAC_VIA_IIci:
 609                         via2[rSIER] = IER_CLR_BIT(irq_idx);
 610                         break;
 611                 case MAC_VIA_QUADRA:
 612                         if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
 613                             (macintosh_config->adb_type != MAC_ADB_PB2))
 614                                 via2[vDirA] |= 1 << irq_idx;
 615                         break;
 616                 }
 617         }
 618 }
 619
 620 void via_irq_clear(int irq) {
 621         int irq_src     = IRQ_SRC(irq);
 622         int irq_idx     = IRQ_IDX(irq);
 623         int irq_bit     = 1 << irq_idx;
 624
 625         if (irq_src == 1) {
 626                 via1[vIFR] = irq_bit;
 627         } else if (irq_src == 2) {
 628                 via2[gIFR] = irq_bit | rbv_clear;
 629         } else if (irq_src == 7) {
 630                 /* FIXME: There is no way to clear an individual nubus slot
 631                  * IRQ flag, other than getting the device to do it.
 632                  */
 633         }
 634 }
 635
 636 /*
 637  * Returns nonzero if an interrupt is pending on the given
 638  * VIA/IRQ combination.
 639  */
 640
 641 int via_irq_pending(int irq)
 642 {
 643         int irq_src     = IRQ_SRC(irq);
 644         int irq_idx     = IRQ_IDX(irq);
 645         int irq_bit     = 1 << irq_idx;
 646
 647         if (irq_src == 1) {
 648                 return via1[vIFR] & irq_bit;
 649         } else if (irq_src == 2) {
 650                 return via2[gIFR] & irq_bit;
 651         } else if (irq_src == 7) {
 652                 /* Always 0 for MAC_VIA_QUADRA if the slot irq is disabled. */
 653                 return ~via2[gBufA] & irq_bit;
 654         }
 655         return 0;
 656 }