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/mac_via.h>
  36 #include <asm/mac_psc.h>
  37 #include <asm/mac_oss.h>
  38
  39 volatile __u8 *via1, *via2;
  40 int rbv_present;
  41 int via_alt_mapping;
  42 EXPORT_SYMBOL(via_alt_mapping);
  43 static __u8 rbv_clear;
  44
  45 /*
  46  * Globals for accessing the VIA chip registers without having to
  47  * check if we're hitting a real VIA or an RBV. Normally you could
  48  * just hit the combined register (ie, vIER|rIER) but that seems to
  49  * break on AV Macs...probably because they actually decode more than
  50  * eight address bits. Why can't Apple engineers at least be
  51  * _consistently_ lazy?                          - 1999-05-21 (jmt)
  52  */
  53
  54 static int gIER,gIFR,gBufA,gBufB;
  55
  56 /*
  57  * Timer defs.
  58  */
  59
  60 #define TICK_SIZE               10000
  61 #define MAC_CLOCK_TICK          (783300/HZ)             /* ticks per HZ */
  62 #define MAC_CLOCK_LOW           (MAC_CLOCK_TICK&0xFF)
  63 #define MAC_CLOCK_HIGH          (MAC_CLOCK_TICK>>8)
  64
  65 /* To disable a NuBus slot on Quadras we make that slot IRQ line an output set
  66  * high. On RBV we just use the slot interrupt enable register. On Macs with
  67  * genuine VIA chips we must use nubus_disabled to keep track of disabled slot
  68  * interrupts. When any slot IRQ is disabled we mask the (edge triggered) CA1
  69  * or "SLOTS" interrupt. When no slot is disabled, we unmask the CA1 interrupt.
  70  * So, on genuine VIAs, having more than one NuBus IRQ can mean trouble,
  71  * because closing one of those drivers can mask all of the NuBus interrupts.
  72  * Also, since we can't mask the unregistered slot IRQs on genuine VIAs, it's
  73  * possible to get interrupts from cards that MacOS or the ROM has configured
  74  * but we have not. FWIW, "Designing Cards and Drivers for Macintosh II and
  75  * Macintosh SE", page 9-8, says, a slot IRQ with no driver would crash MacOS.
  76  */
  77 static u8 nubus_disabled;
  78
  79 void via_debug_dump(void);
  80 irqreturn_t via1_irq(int, void *);
  81 irqreturn_t via2_irq(int, void *);
  82 irqreturn_t via_nubus_irq(int, void *);
  83 void via_irq_enable(int irq);
  84 void via_irq_disable(int irq);
  85 void via_irq_clear(int irq);
  86
  87 /*
  88  * Initialize the VIAs
  89  *
  90  * First we figure out where they actually _are_ as well as what type of
  91  * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
  92  * Then we pretty much clear them out and disable all IRQ sources.
  93  *
  94  * Note: the OSS is actually "detected" here and not in oss_init(). It just
  95  *       seems more logical to do it here since via_init() needs to know
  96  *       these things anyways.
  97  */
  98
  99 void __init via_init(void)
 100 {
 101         switch(macintosh_config->via_type) {
 102
 103                 /* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
 104
 105                 case MAC_VIA_IIci:
 106                         via1 = (void *) VIA1_BASE;
 107                         if (macintosh_config->ident == MAC_MODEL_IIFX) {
 108                                 via2 = NULL;
 109                                 rbv_present = 0;
 110                                 oss_present = 1;
 111                         } else {
 112                                 via2 = (void *) RBV_BASE;
 113                                 rbv_present = 1;
 114                                 oss_present = 0;
 115                         }
 116                         if (macintosh_config->ident == MAC_MODEL_LCIII) {
 117                                 rbv_clear = 0x00;
 118                         } else {
 119                                 /* on most RBVs (& unlike the VIAs), you   */
 120                                 /* need to set bit 7 when you write to IFR */
 121                                 /* in order for your clear to occur.       */
 122                                 rbv_clear = 0x80;
 123                         }
 124                         gIER = rIER;
 125                         gIFR = rIFR;
 126                         gBufA = rSIFR;
 127                         gBufB = rBufB;
 128                         break;
 129
 130                 /* Quadra and early MacIIs agree on the VIA locations */
 131
 132                 case MAC_VIA_QUADRA:
 133                 case MAC_VIA_II:
 134                         via1 = (void *) VIA1_BASE;
 135                         via2 = (void *) VIA2_BASE;
 136                         rbv_present = 0;
 137                         oss_present = 0;
 138                         rbv_clear = 0x00;
 139                         gIER = vIER;
 140                         gIFR = vIFR;
 141                         gBufA = vBufA;
 142                         gBufB = vBufB;
 143                         break;
 144                 default:
 145                         panic("UNKNOWN VIA TYPE");
 146         }
 147
 148         printk(KERN_INFO "VIA1 at %p is a 6522 or clone\n", via1);
 149
 150         printk(KERN_INFO "VIA2 at %p is ", via2);
 151         if (rbv_present) {
 152                 printk("an RBV\n");
 153         } else if (oss_present) {
 154                 printk("an OSS\n");
 155         } else {
 156                 printk("a 6522 or clone\n");
 157         }
 158
 159 #ifdef DEBUG_VIA
 160         via_debug_dump();
 161 #endif
 162
 163         /*
 164          * Shut down all IRQ sources, reset the timers, and
 165          * kill the timer latch on VIA1.
 166          */
 167
 168         via1[vIER] = 0x7F;
 169         via1[vIFR] = 0x7F;
 170         via1[vT1LL] = 0;
 171         via1[vT1LH] = 0;
 172         via1[vT1CL] = 0;
 173         via1[vT1CH] = 0;
 174         via1[vT2CL] = 0;
 175         via1[vT2CH] = 0;
 176         via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
 177         via1[vACR] &= ~0x03; /* disable port A & B latches */
 178
 179         /*
 180          * SE/30: disable video IRQ
 181          * XXX: testing for SE/30 VBL
 182          */
 183
 184         if (macintosh_config->ident == MAC_MODEL_SE30) {
 185                 via1[vDirB] |= 0x40;
 186                 via1[vBufB] |= 0x40;
 187         }
 188
 189         /*
 190          * Set the RTC bits to a known state: all lines to outputs and
 191          * RTC disabled (yes that's 0 to enable and 1 to disable).
 192          */
 193
 194         via1[vDirB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData);
 195         via1[vBufB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk);
 196
 197         /* Everything below this point is VIA2/RBV only... */
 198
 199         if (oss_present)
 200                 return;
 201
 202         /* Some machines support an alternate IRQ mapping that spreads  */
 203         /* Ethernet and Sound out to their own autolevel IRQs and moves */
 204         /* VIA1 to level 6. A/UX uses this mapping and we do too.  Note */
 205         /* that the IIfx emulates this alternate mapping using the OSS. */
 206
 207         via_alt_mapping = 0;
 208         if (macintosh_config->via_type == MAC_VIA_QUADRA)
 209                 switch (macintosh_config->ident) {
 210                 case MAC_MODEL_C660:
 211                 case MAC_MODEL_Q840:
 212                         /* not applicable */
 213                         break;
 214                 case MAC_MODEL_P588:
 215                 case MAC_MODEL_TV:
 216                 case MAC_MODEL_PB140:
 217                 case MAC_MODEL_PB145:
 218                 case MAC_MODEL_PB160:
 219                 case MAC_MODEL_PB165:
 220                 case MAC_MODEL_PB165C:
 221                 case MAC_MODEL_PB170:
 222                 case MAC_MODEL_PB180:
 223                 case MAC_MODEL_PB180C:
 224                 case MAC_MODEL_PB190:
 225                 case MAC_MODEL_PB520:
 226                         /* not yet tested */
 227                         break;
 228                 default:
 229                         via_alt_mapping = 1;
 230                         via1[vDirB] |= 0x40;
 231                         via1[vBufB] &= ~0x40;
 232                         break;
 233                 }
 234
 235         /*
 236          * Now initialize VIA2. For RBV we just kill all interrupts;
 237          * for a regular VIA we also reset the timers and stuff.
 238          */
 239
 240         via2[gIER] = 0x7F;
 241         via2[gIFR] = 0x7F | rbv_clear;
 242         if (!rbv_present) {
 243                 via2[vT1LL] = 0;
 244                 via2[vT1LH] = 0;
 245                 via2[vT1CL] = 0;
 246                 via2[vT1CH] = 0;
 247                 via2[vT2CL] = 0;
 248                 via2[vT2CH] = 0;
 249                 via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
 250                 via2[vACR] &= ~0x03; /* disable port A & B latches */
 251         }
 252
 253         /*
 254          * Set vPCR for control line interrupts (but not on RBV)
 255          */
 256         if (!rbv_present) {
 257                 /* For all VIA types, CA1 (SLOTS IRQ) and CB1 (ASC IRQ)
 258                  * are made negative edge triggered here.
 259                  */
 260                 if (macintosh_config->scsi_type == MAC_SCSI_OLD) {
 261                         /* CB2 (IRQ) indep. input, positive edge */
 262                         /* CA2 (DRQ) indep. input, positive edge */
 263                         via2[vPCR] = 0x66;
 264                 } else {
 265                         /* CB2 (IRQ) indep. input, negative edge */
 266                         /* CA2 (DRQ) indep. input, negative edge */
 267                         via2[vPCR] = 0x22;
 268                 }
 269         }
 270 }
 271
 272 /*
 273  * Start the 100 Hz clock
 274  */
 275
 276 void __init via_init_clock(irq_handler_t func)
 277 {
 278         via1[vACR] |= 0x40;
 279         via1[vT1LL] = MAC_CLOCK_LOW;
 280         via1[vT1LH] = MAC_CLOCK_HIGH;
 281         via1[vT1CL] = MAC_CLOCK_LOW;
 282         via1[vT1CH] = MAC_CLOCK_HIGH;
 283
 284         if (request_irq(IRQ_MAC_TIMER_1, func, 0, "timer", func))
 285                 pr_err("Couldn't register %s interrupt\n", "timer");
 286 }
 287
 288 /*
 289  * Register the interrupt dispatchers for VIA or RBV machines only.
 290  */
 291
 292 void __init via_register_interrupts(void)
 293 {
 294         if (via_alt_mapping) {
 295                 if (request_irq(IRQ_AUTO_1, via1_irq, 0, "software",
 296                                 (void *)via1))
 297                         pr_err("Couldn't register %s interrupt\n", "software");
 298                 if (request_irq(IRQ_AUTO_6, via1_irq, 0, "via1", (void *)via1))
 299                         pr_err("Couldn't register %s interrupt\n", "via1");
 300         } else {
 301                 if (request_irq(IRQ_AUTO_1, via1_irq, 0, "via1", (void *)via1))
 302                         pr_err("Couldn't register %s interrupt\n", "via1");
 303         }
 304         if (request_irq(IRQ_AUTO_2, via2_irq, 0, "via2", (void *)via2))
 305                 pr_err("Couldn't register %s interrupt\n", "via2");
 306         if (request_irq(IRQ_MAC_NUBUS, via_nubus_irq, 0, "nubus",
 307                         (void *)via2))
 308                 pr_err("Couldn't register %s interrupt\n", "nubus");
 309 }
 310
 311 /*
 312  * Debugging dump, used in various places to see what's going on.
 313  */
 314
 315 void via_debug_dump(void)
 316 {
 317         printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
 318                 (uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
 319         printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
 320                 (uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
 321         if (oss_present) {
 322                 printk(KERN_DEBUG "VIA2: <OSS>\n");
 323         } else if (rbv_present) {
 324                 printk(KERN_DEBUG "VIA2:  IFR = 0x%02X  IER = 0x%02X\n",
 325                         (uint) via2[rIFR], (uint) via2[rIER]);
 326                 printk(KERN_DEBUG "      SIFR = 0x%02X SIER = 0x%02X\n",
 327                         (uint) via2[rSIFR], (uint) via2[rSIER]);
 328         } else {
 329                 printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
 330                         (uint) via2[vDirA], (uint) via2[vDirB],
 331                         (uint) via2[vACR]);
 332                 printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
 333                         (uint) via2[vPCR],
 334                         (uint) via2[vIFR], (uint) via2[vIER]);
 335         }
 336 }
 337
 338 /*
 339  * This is always executed with interrupts disabled.
 340  *
 341  * TBI: get time offset between scheduling timer ticks
 342  */
 343
 344 unsigned long mac_gettimeoffset (void)
 345 {
 346         unsigned long ticks, offset = 0;
 347
 348         /* read VIA1 timer 2 current value */
 349         ticks = via1[vT1CL] | (via1[vT1CH] << 8);
 350         /* The probability of underflow is less than 2% */
 351         if (ticks > MAC_CLOCK_TICK - MAC_CLOCK_TICK / 50)
 352                 /* Check for pending timer interrupt in VIA1 IFR */
 353                 if (via1[vIFR] & 0x40) offset = TICK_SIZE;
 354
 355         ticks = MAC_CLOCK_TICK - ticks;
 356         ticks = ticks * 10000L / MAC_CLOCK_TICK;
 357
 358         return ticks + offset;
 359 }
 360
 361 /*
 362  * Flush the L2 cache on Macs that have it by flipping
 363  * the system into 24-bit mode for an instant.
 364  */
 365
 366 void via_flush_cache(void)
 367 {
 368         via2[gBufB] &= ~VIA2B_vMode32;
 369         via2[gBufB] |= VIA2B_vMode32;
 370 }
 371
 372 /*
 373  * Return the status of the L2 cache on a IIci
 374  */
 375
 376 int via_get_cache_disable(void)
 377 {
 378         /* Safeguard against being called accidentally */
 379         if (!via2) {
 380                 printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
 381                 return 1;
 382         }
 383
 384         return (int) via2[gBufB] & VIA2B_vCDis;
 385 }
 386
 387 /*
 388  * Initialize VIA2 for Nubus access
 389  */
 390
 391 void __init via_nubus_init(void)
 392 {
 393         /* unlock nubus transactions */
 394
 395         if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
 396             (macintosh_config->adb_type != MAC_ADB_PB2)) {
 397                 /* set the line to be an output on non-RBV machines */
 398                 if (!rbv_present)
 399                         via2[vDirB] |= 0x02;
 400
 401                 /* this seems to be an ADB bit on PMU machines */
 402                 /* according to MkLinux.  -- jmt               */
 403                 via2[gBufB] |= 0x02;
 404         }
 405
 406         /* Disable all the slot interrupts (where possible). */
 407
 408         switch (macintosh_config->via_type) {
 409         case MAC_VIA_II:
 410                 /* Just make the port A lines inputs. */
 411                 switch(macintosh_config->ident) {
 412                 case MAC_MODEL_II:
 413                 case MAC_MODEL_IIX:
 414                 case MAC_MODEL_IICX:
 415                 case MAC_MODEL_SE30:
 416                         /* The top two bits are RAM size outputs. */
 417                         via2[vDirA] &= 0xC0;
 418                         break;
 419                 default:
 420                         via2[vDirA] &= 0x80;
 421                 }
 422                 break;
 423         case MAC_VIA_IIci:
 424                 /* RBV. Disable all the slot interrupts. SIER works like IER. */
 425                 via2[rSIER] = 0x7F;
 426                 break;
 427         case MAC_VIA_QUADRA:
 428                 /* Disable the inactive slot interrupts by making those lines outputs. */
 429                 if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
 430                     (macintosh_config->adb_type != MAC_ADB_PB2)) {
 431                         via2[vBufA] |= 0x7F;
 432                         via2[vDirA] |= 0x7F;
 433                 }
 434                 break;
 435         }
 436 }
 437
 438 /*
 439  * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
 440  * via6522.c :-), disable/pending masks added.
 441  */
 442
 443 irqreturn_t via1_irq(int irq, void *dev_id)
 444 {
 445         int irq_num;
 446         unsigned char irq_bit, events;
 447
 448         events = via1[vIFR] & via1[vIER] & 0x7F;
 449         if (!events)
 450                 return IRQ_NONE;
 451
 452         irq_num = VIA1_SOURCE_BASE;
 453         irq_bit = 1;
 454         do {
 455                 if (events & irq_bit) {
 456                         via1[vIFR] = irq_bit;
 457                         generic_handle_irq(irq_num);
 458                 }
 459                 ++irq_num;
 460                 irq_bit <<= 1;
 461         } while (events >= irq_bit);
 462         return IRQ_HANDLED;
 463 }
 464
 465 irqreturn_t via2_irq(int irq, void *dev_id)
 466 {
 467         int irq_num;
 468         unsigned char irq_bit, events;
 469
 470         events = via2[gIFR] & via2[gIER] & 0x7F;
 471         if (!events)
 472                 return IRQ_NONE;
 473
 474         irq_num = VIA2_SOURCE_BASE;
 475         irq_bit = 1;
 476         do {
 477                 if (events & irq_bit) {
 478                         via2[gIFR] = irq_bit | rbv_clear;
 479                         generic_handle_irq(irq_num);
 480                 }
 481                 ++irq_num;
 482                 irq_bit <<= 1;
 483         } while (events >= irq_bit);
 484         return IRQ_HANDLED;
 485 }
 486
 487 /*
 488  * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
 489  * VIA2 dispatcher as a fast interrupt handler.
 490  */
 491
 492 irqreturn_t via_nubus_irq(int irq, void *dev_id)
 493 {
 494         int slot_irq;
 495         unsigned char slot_bit, events;
 496
 497         events = ~via2[gBufA] & 0x7F;
 498         if (rbv_present)
 499                 events &= via2[rSIER];
 500         else
 501                 events &= ~via2[vDirA];
 502         if (!events)
 503                 return IRQ_NONE;
 504
 505         do {
 506                 slot_irq = IRQ_NUBUS_F;
 507                 slot_bit = 0x40;
 508                 do {
 509                         if (events & slot_bit) {
 510                                 events &= ~slot_bit;
 511                                 generic_handle_irq(slot_irq);
 512                         }
 513                         --slot_irq;
 514                         slot_bit >>= 1;
 515                 } while (events);
 516
 517                 /* clear the CA1 interrupt and make certain there's no more. */
 518                 via2[gIFR] = 0x02 | rbv_clear;
 519                 events = ~via2[gBufA] & 0x7F;
 520                 if (rbv_present)
 521                         events &= via2[rSIER];
 522                 else
 523                         events &= ~via2[vDirA];
 524         } while (events);
 525         return IRQ_HANDLED;
 526 }
 527
 528 void via_irq_enable(int irq) {
 529         int irq_src     = IRQ_SRC(irq);
 530         int irq_idx     = IRQ_IDX(irq);
 531
 532 #ifdef DEBUG_IRQUSE
 533         printk(KERN_DEBUG "via_irq_enable(%d)\n", irq);
 534 #endif
 535
 536         if (irq_src == 1) {
 537                 via1[vIER] = IER_SET_BIT(irq_idx);
 538         } else if (irq_src == 2) {
 539                 if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
 540                         via2[gIER] = IER_SET_BIT(irq_idx);
 541         } else if (irq_src == 7) {
 542                 switch (macintosh_config->via_type) {
 543                 case MAC_VIA_II:
 544                         nubus_disabled &= ~(1 << irq_idx);
 545                         /* Enable the CA1 interrupt when no slot is disabled. */
 546                         if (!nubus_disabled)
 547                                 via2[gIER] = IER_SET_BIT(1);
 548                         break;
 549                 case MAC_VIA_IIci:
 550                         /* On RBV, enable the slot interrupt.
 551                          * SIER works like IER.
 552                          */
 553                         via2[rSIER] = IER_SET_BIT(irq_idx);
 554                         break;
 555                 case MAC_VIA_QUADRA:
 556                         /* Make the port A line an input to enable the slot irq.
 557                          * But not on PowerBooks, that's ADB.
 558                          */
 559                         if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
 560                             (macintosh_config->adb_type != MAC_ADB_PB2))
 561                                 via2[vDirA] &= ~(1 << irq_idx);
 562                         break;
 563                 }
 564         }
 565 }
 566
 567 void via_irq_disable(int irq) {
 568         int irq_src     = IRQ_SRC(irq);
 569         int irq_idx     = IRQ_IDX(irq);
 570
 571 #ifdef DEBUG_IRQUSE
 572         printk(KERN_DEBUG "via_irq_disable(%d)\n", irq);
 573 #endif
 574
 575         if (irq_src == 1) {
 576                 via1[vIER] = IER_CLR_BIT(irq_idx);
 577         } else if (irq_src == 2) {
 578                 via2[gIER] = IER_CLR_BIT(irq_idx);
 579         } else if (irq_src == 7) {
 580                 switch (macintosh_config->via_type) {
 581                 case MAC_VIA_II:
 582                         nubus_disabled |= 1 << irq_idx;
 583                         if (nubus_disabled)
 584                                 via2[gIER] = IER_CLR_BIT(1);
 585                         break;
 586                 case MAC_VIA_IIci:
 587                         via2[rSIER] = IER_CLR_BIT(irq_idx);
 588                         break;
 589                 case MAC_VIA_QUADRA:
 590                         if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
 591                             (macintosh_config->adb_type != MAC_ADB_PB2))
 592                                 via2[vDirA] |= 1 << irq_idx;
 593                         break;
 594                 }
 595         }
 596 }
 597
 598 void via_irq_clear(int irq) {
 599         int irq_src     = IRQ_SRC(irq);
 600         int irq_idx     = IRQ_IDX(irq);
 601         int irq_bit     = 1 << irq_idx;
 602
 603         if (irq_src == 1) {
 604                 via1[vIFR] = irq_bit;
 605         } else if (irq_src == 2) {
 606                 via2[gIFR] = irq_bit | rbv_clear;
 607         } else if (irq_src == 7) {
 608                 /* FIXME: There is no way to clear an individual nubus slot
 609                  * IRQ flag, other than getting the device to do it.
 610                  */
 611         }
 612 }
 613
 614 /*
 615  * Returns nonzero if an interrupt is pending on the given
 616  * VIA/IRQ combination.
 617  */
 618
 619 int via_irq_pending(int irq)
 620 {
 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                 return via1[vIFR] & irq_bit;
 627         } else if (irq_src == 2) {
 628                 return via2[gIFR] & irq_bit;
 629         } else if (irq_src == 7) {
 630                 /* Always 0 for MAC_VIA_QUADRA if the slot irq is disabled. */
 631                 return ~via2[gBufA] & irq_bit;
 632         }
 633         return 0;
 634 }
 635
 636 void via1_set_head(int head)
 637 {
 638         if (head == 0)
 639                 via1[vBufA] &= ~VIA1A_vHeadSel;
 640         else
 641                 via1[vBufA] |= VIA1A_vHeadSel;
 642 }
 643 EXPORT_SYMBOL(via1_set_head);