xref: /openbmc/linux/arch/m68k/mac/via.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  *	6522 Versatile Interface Adapter (VIA)
3  *
4  *	There are two of these on the Mac II. Some IRQ's 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/ide.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, via_alt_mapping;
45 __u8 rbv_clear;
46 
47 /*
48  * Globals for accessing the VIA chip registers without having to
49  * check if we're hitting a real VIA or an RBV. Normally you could
50  * just hit the combined register (ie, vIER|rIER) but that seems to
51  * break on AV Macs...probably because they actually decode more than
52  * eight address bits. Why can't Apple engineers at least be
53  * _consistently_ lazy?                          - 1999-05-21 (jmt)
54  */
55 
56 static int gIER,gIFR,gBufA,gBufB;
57 
58 /*
59  * Timer defs.
60  */
61 
62 #define TICK_SIZE		10000
63 #define MAC_CLOCK_TICK		(783300/HZ)		/* ticks per HZ */
64 #define MAC_CLOCK_LOW		(MAC_CLOCK_TICK&0xFF)
65 #define MAC_CLOCK_HIGH		(MAC_CLOCK_TICK>>8)
66 
67 /* To disable a NuBus slot on Quadras we make the slot IRQ lines outputs, set
68  * high. On RBV we just use the slot interrupt enable register. On Macs with
69  * genuine VIA chips we must use nubus_disabled to keep track of disabled slot
70  * interrupts. When any slot IRQ is disabled we mask the (edge triggered) CA1
71  * or "SLOTS" interrupt. When no slot is disabled, we unmask the CA1 interrupt.
72  * So, on genuine VIAs, having more than one NuBus IRQ can mean trouble,
73  * because closing one of those drivers can mask all of the NuBus interrupts.
74  * Also, since we can't mask the unregistered slot IRQs on genuine VIAs, it's
75  * possible to get interrupts from cards that MacOS or the ROM has configured
76  * but we have not. FWIW, "Designing Cards and Drivers for Macintosh II and
77  * Macintosh SE", page 9-8, says, a slot IRQ with no driver would crash MacOS.
78  */
79 static u8 nubus_disabled;
80 
81 void via_debug_dump(void);
82 irqreturn_t via1_irq(int, void *);
83 irqreturn_t via2_irq(int, void *);
84 irqreturn_t via_nubus_irq(int, void *);
85 void via_irq_enable(int irq);
86 void via_irq_disable(int irq);
87 void via_irq_clear(int irq);
88 
89 extern irqreturn_t mac_scc_dispatch(int, void *);
90 extern int oss_present;
91 
92 /*
93  * Initialize the VIAs
94  *
95  * First we figure out where they actually _are_ as well as what type of
96  * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
97  * Then we pretty much clear them out and disable all IRQ sources.
98  *
99  * Note: the OSS is actually "detected" here and not in oss_init(). It just
100  *	 seems more logical to do it here since via_init() needs to know
101  *	 these things anyways.
102  */
103 
104 void __init via_init(void)
105 {
106 	switch(macintosh_config->via_type) {
107 
108 		/* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
109 
110 		case MAC_VIA_IIci:
111 			via1 = (void *) VIA1_BASE;
112 			if (macintosh_config->ident == MAC_MODEL_IIFX) {
113 				via2 = NULL;
114 				rbv_present = 0;
115 				oss_present = 1;
116 			} else {
117 				via2 = (void *) RBV_BASE;
118 				rbv_present = 1;
119 				oss_present = 0;
120 			}
121 			if (macintosh_config->ident == MAC_MODEL_LCIII) {
122 				rbv_clear = 0x00;
123 			} else {
124 				/* on most RBVs (& unlike the VIAs), you   */
125 				/* need to set bit 7 when you write to IFR */
126 				/* in order for your clear to occur.       */
127 				rbv_clear = 0x80;
128 			}
129 			gIER = rIER;
130 			gIFR = rIFR;
131 			gBufA = rSIFR;
132 			gBufB = rBufB;
133 			break;
134 
135 		/* Quadra and early MacIIs agree on the VIA locations */
136 
137 		case MAC_VIA_QUADRA:
138 		case MAC_VIA_II:
139 			via1 = (void *) VIA1_BASE;
140 			via2 = (void *) VIA2_BASE;
141 			rbv_present = 0;
142 			oss_present = 0;
143 			rbv_clear = 0x00;
144 			gIER = vIER;
145 			gIFR = vIFR;
146 			gBufA = vBufA;
147 			gBufB = vBufB;
148 			break;
149 		default:
150 			panic("UNKNOWN VIA TYPE");
151 	}
152 
153 	printk(KERN_INFO "VIA1 at %p is a 6522 or clone\n", via1);
154 
155 	printk(KERN_INFO "VIA2 at %p is ", via2);
156 	if (rbv_present) {
157 		printk("an RBV\n");
158 	} else if (oss_present) {
159 		printk("an OSS\n");
160 	} else {
161 		printk("a 6522 or clone\n");
162 	}
163 
164 #ifdef DEBUG_VIA
165 	via_debug_dump();
166 #endif
167 
168 	/*
169 	 * Shut down all IRQ sources, reset the timers, and
170 	 * kill the timer latch on VIA1.
171 	 */
172 
173 	via1[vIER] = 0x7F;
174 	via1[vIFR] = 0x7F;
175 	via1[vT1LL] = 0;
176 	via1[vT1LH] = 0;
177 	via1[vT1CL] = 0;
178 	via1[vT1CH] = 0;
179 	via1[vT2CL] = 0;
180 	via1[vT2CH] = 0;
181 	via1[vACR] &= 0x3F;
182 	via1[vACR] &= ~0x03; /* disable port A & B latches */
183 
184 	/*
185 	 * SE/30: disable video IRQ
186 	 * XXX: testing for SE/30 VBL
187 	 */
188 
189 	if (macintosh_config->ident == MAC_MODEL_SE30) {
190 		via1[vDirB] |= 0x40;
191 		via1[vBufB] |= 0x40;
192 	}
193 
194 	/*
195 	 * Set the RTC bits to a known state: all lines to outputs and
196 	 * RTC disabled (yes that's 0 to enable and 1 to disable).
197 	 */
198 
199 	via1[vDirB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData);
200 	via1[vBufB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk);
201 
202 	/* Everything below this point is VIA2/RBV only... */
203 
204 	if (oss_present) return;
205 
206 #if 1
207 	/* Some machines support an alternate IRQ mapping that spreads  */
208 	/* Ethernet and Sound out to their own autolevel IRQs and moves */
209 	/* VIA1 to level 6. A/UX uses this mapping and we do too.  Note */
210 	/* that the IIfx emulates this alternate mapping using the OSS. */
211 
212 	switch(macintosh_config->ident) {
213 		case MAC_MODEL_P475:
214 		case MAC_MODEL_P475F:
215 		case MAC_MODEL_P575:
216 		case MAC_MODEL_Q605:
217 		case MAC_MODEL_Q605_ACC:
218 		case MAC_MODEL_C610:
219 		case MAC_MODEL_Q610:
220 		case MAC_MODEL_Q630:
221 		case MAC_MODEL_C650:
222 		case MAC_MODEL_Q650:
223 		case MAC_MODEL_Q700:
224 		case MAC_MODEL_Q800:
225 		case MAC_MODEL_Q900:
226 		case MAC_MODEL_Q950:
227 			via_alt_mapping = 1;
228 			via1[vDirB] |= 0x40;
229 			via1[vBufB] &= ~0x40;
230 			break;
231 		default:
232 			via_alt_mapping = 0;
233 			break;
234 	}
235 #else
236 	via_alt_mapping = 0;
237 #endif
238 
239 	/*
240 	 * Now initialize VIA2. For RBV we just kill all interrupts;
241 	 * for a regular VIA we also reset the timers and stuff.
242 	 */
243 
244 	via2[gIER] = 0x7F;
245 	via2[gIFR] = 0x7F | rbv_clear;
246 	if (!rbv_present) {
247 		via2[vT1LL] = 0;
248 		via2[vT1LH] = 0;
249 		via2[vT1CL] = 0;
250 		via2[vT1CH] = 0;
251 		via2[vT2CL] = 0;
252 		via2[vT2CH] = 0;
253 		via2[vACR] &= 0x3F;
254 		via2[vACR] &= ~0x03; /* disable port A & B latches */
255 	}
256 
257 	/*
258 	 * Set vPCR for SCSI interrupts (but not on RBV)
259 	 */
260 	if (!rbv_present) {
261 		if (macintosh_config->scsi_type == MAC_SCSI_OLD) {
262 			/* CB2 (IRQ) indep. input, positive edge */
263 			/* CA2 (DRQ) indep. input, positive edge */
264 			via2[vPCR] = 0x66;
265 		} else {
266 			/* CB2 (IRQ) indep. input, negative edge */
267 			/* CA2 (DRQ) indep. input, negative edge */
268 			via2[vPCR] = 0x22;
269 		}
270 	}
271 }
272 
273 /*
274  * Start the 100 Hz clock
275  */
276 
277 void __init via_init_clock(irq_handler_t func)
278 {
279 	via1[vACR] |= 0x40;
280 	via1[vT1LL] = MAC_CLOCK_LOW;
281 	via1[vT1LH] = MAC_CLOCK_HIGH;
282 	via1[vT1CL] = MAC_CLOCK_LOW;
283 	via1[vT1CH] = MAC_CLOCK_HIGH;
284 
285 	request_irq(IRQ_MAC_TIMER_1, func, IRQ_FLG_LOCK, "timer", func);
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 		request_irq(IRQ_AUTO_1, via1_irq,
296 				IRQ_FLG_LOCK|IRQ_FLG_FAST, "software",
297 				(void *) via1);
298 		request_irq(IRQ_AUTO_6, via1_irq,
299 				IRQ_FLG_LOCK|IRQ_FLG_FAST, "via1",
300 				(void *) via1);
301 	} else {
302 		request_irq(IRQ_AUTO_1, via1_irq,
303 				IRQ_FLG_LOCK|IRQ_FLG_FAST, "via1",
304 				(void *) via1);
305 	}
306 	request_irq(IRQ_AUTO_2, via2_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
307 			"via2", (void *) via2);
308 	if (!psc_present) {
309 		request_irq(IRQ_AUTO_4, mac_scc_dispatch, IRQ_FLG_LOCK,
310 				"scc", mac_scc_dispatch);
311 	}
312 	request_irq(IRQ_MAC_NUBUS, via_nubus_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
313 			"nubus", (void *) via2);
314 }
315 
316 /*
317  * Debugging dump, used in various places to see what's going on.
318  */
319 
320 void via_debug_dump(void)
321 {
322 	printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
323 		(uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
324 	printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
325 		(uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
326 	if (oss_present) {
327 		printk(KERN_DEBUG "VIA2: <OSS>\n");
328 	} else if (rbv_present) {
329 		printk(KERN_DEBUG "VIA2:  IFR = 0x%02X  IER = 0x%02X\n",
330 			(uint) via2[rIFR], (uint) via2[rIER]);
331 		printk(KERN_DEBUG "      SIFR = 0x%02X SIER = 0x%02X\n",
332 			(uint) via2[rSIFR], (uint) via2[rSIER]);
333 	} else {
334 		printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
335 			(uint) via2[vDirA], (uint) via2[vDirB],
336 			(uint) via2[vACR]);
337 		printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
338 			(uint) via2[vPCR],
339 			(uint) via2[vIFR], (uint) via2[vIER]);
340 	}
341 }
342 
343 /*
344  * This is always executed with interrupts disabled.
345  *
346  * TBI: get time offset between scheduling timer ticks
347  */
348 
349 unsigned long mac_gettimeoffset (void)
350 {
351 	unsigned long ticks, offset = 0;
352 
353 	/* read VIA1 timer 2 current value */
354 	ticks = via1[vT1CL] | (via1[vT1CH] << 8);
355 	/* The probability of underflow is less than 2% */
356 	if (ticks > MAC_CLOCK_TICK - MAC_CLOCK_TICK / 50)
357 		/* Check for pending timer interrupt in VIA1 IFR */
358 		if (via1[vIFR] & 0x40) offset = TICK_SIZE;
359 
360 	ticks = MAC_CLOCK_TICK - ticks;
361 	ticks = ticks * 10000L / MAC_CLOCK_TICK;
362 
363 	return ticks + offset;
364 }
365 
366 /*
367  * Flush the L2 cache on Macs that have it by flipping
368  * the system into 24-bit mode for an instant.
369  */
370 
371 void via_flush_cache(void)
372 {
373 	via2[gBufB] &= ~VIA2B_vMode32;
374 	via2[gBufB] |= VIA2B_vMode32;
375 }
376 
377 /*
378  * Return the status of the L2 cache on a IIci
379  */
380 
381 int via_get_cache_disable(void)
382 {
383 	/* Safeguard against being called accidentally */
384 	if (!via2) {
385 		printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
386 		return 1;
387 	}
388 
389 	return (int) via2[gBufB] & VIA2B_vCDis;
390 }
391 
392 /*
393  * Initialize VIA2 for Nubus access
394  */
395 
396 void __init via_nubus_init(void)
397 {
398 	/* unlock nubus transactions */
399 
400 	if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
401 	    (macintosh_config->adb_type != MAC_ADB_PB2)) {
402 		/* set the line to be an output on non-RBV machines */
403 		if (!rbv_present)
404 			via2[vDirB] |= 0x02;
405 
406 		/* this seems to be an ADB bit on PMU machines */
407 		/* according to MkLinux.  -- jmt               */
408 		via2[gBufB] |= 0x02;
409 	}
410 
411 	/* Disable all the slot interrupts (where possible). */
412 
413 	switch (macintosh_config->via_type) {
414 	case MAC_VIA_II:
415 		/* Just make the port A lines inputs. */
416 		switch(macintosh_config->ident) {
417 		case MAC_MODEL_II:
418 		case MAC_MODEL_IIX:
419 		case MAC_MODEL_IICX:
420 		case MAC_MODEL_SE30:
421 			/* The top two bits are RAM size outputs. */
422 			via2[vDirA] &= 0xC0;
423 			break;
424 		default:
425 			via2[vDirA] &= 0x80;
426 		}
427 		break;
428 	case MAC_VIA_IIci:
429 		/* RBV. Disable all the slot interrupts. SIER works like IER. */
430 		via2[rSIER] = 0x7F;
431 		break;
432 	case MAC_VIA_QUADRA:
433 		/* Disable the inactive slot interrupts by making those lines outputs. */
434 		if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
435 		    (macintosh_config->adb_type != MAC_ADB_PB2)) {
436 			via2[vBufA] |= 0x7F;
437 			via2[vDirA] |= 0x7F;
438 		}
439 		break;
440 	}
441 }
442 
443 /*
444  * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
445  * via6522.c :-), disable/pending masks added.
446  */
447 
448 irqreturn_t via1_irq(int irq, void *dev_id)
449 {
450 	int irq_num;
451 	unsigned char irq_bit, events;
452 
453 	events = via1[vIFR] & via1[vIER] & 0x7F;
454 	if (!events)
455 		return IRQ_NONE;
456 
457 	irq_num = VIA1_SOURCE_BASE;
458 	irq_bit = 1;
459 	do {
460 		if (events & irq_bit) {
461 			via1[vIFR] = irq_bit;
462 			m68k_handle_int(irq_num);
463 		}
464 		++irq_num;
465 		irq_bit <<= 1;
466 	} while (events >= irq_bit);
467 
468 #if 0 /* freakin' pmu is doing weird stuff */
469 	if (!oss_present) {
470 		/* This (still) seems to be necessary to get IDE
471 		   working.  However, if you enable VBL interrupts,
472 		   you're screwed... */
473 		/* FIXME: should we check the SLOTIRQ bit before
474                    pulling this stunt? */
475 		/* No, it won't be set. that's why we're doing this. */
476 		via_irq_disable(IRQ_MAC_NUBUS);
477 		via_irq_clear(IRQ_MAC_NUBUS);
478 		m68k_handle_int(IRQ_MAC_NUBUS);
479 		via_irq_enable(IRQ_MAC_NUBUS);
480 	}
481 #endif
482 	return IRQ_HANDLED;
483 }
484 
485 irqreturn_t via2_irq(int irq, void *dev_id)
486 {
487 	int irq_num;
488 	unsigned char irq_bit, events;
489 
490 	events = via2[gIFR] & via2[gIER] & 0x7F;
491 	if (!events)
492 		return IRQ_NONE;
493 
494 	irq_num = VIA2_SOURCE_BASE;
495 	irq_bit = 1;
496 	do {
497 		if (events & irq_bit) {
498 			via2[gIFR] = irq_bit | rbv_clear;
499 			m68k_handle_int(irq_num);
500 		}
501 		++irq_num;
502 		irq_bit <<= 1;
503 	} while (events >= irq_bit);
504 	return IRQ_HANDLED;
505 }
506 
507 /*
508  * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
509  * VIA2 dispatcher as a fast interrupt handler.
510  */
511 
512 irqreturn_t via_nubus_irq(int irq, void *dev_id)
513 {
514 	int slot_irq;
515 	unsigned char slot_bit, events;
516 
517 	events = ~via2[gBufA] & 0x7F;
518 	if (rbv_present)
519 		events &= via2[rSIER];
520 	else
521 		events &= ~via2[vDirA];
522 	if (!events)
523 		return IRQ_NONE;
524 
525 	do {
526 		slot_irq = IRQ_NUBUS_F;
527 		slot_bit = 0x40;
528 		do {
529 			if (events & slot_bit) {
530 				events &= ~slot_bit;
531 				m68k_handle_int(slot_irq);
532 			}
533 			--slot_irq;
534 			slot_bit >>= 1;
535 		} while (events);
536 
537  		/* clear the CA1 interrupt and make certain there's no more. */
538 		via2[gIFR] = 0x02 | rbv_clear;
539 		events = ~via2[gBufA] & 0x7F;
540 		if (rbv_present)
541 			events &= via2[rSIER];
542 		else
543 			events &= ~via2[vDirA];
544 	} while (events);
545 	return IRQ_HANDLED;
546 }
547 
548 void via_irq_enable(int irq) {
549 	int irq_src	= IRQ_SRC(irq);
550 	int irq_idx	= IRQ_IDX(irq);
551 
552 #ifdef DEBUG_IRQUSE
553 	printk(KERN_DEBUG "via_irq_enable(%d)\n", irq);
554 #endif
555 
556 	if (irq_src == 1) {
557 		via1[vIER] = IER_SET_BIT(irq_idx);
558 	} else if (irq_src == 2) {
559 		if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
560 			via2[gIER] = IER_SET_BIT(irq_idx);
561 	} else if (irq_src == 7) {
562 		switch (macintosh_config->via_type) {
563 		case MAC_VIA_II:
564 			nubus_disabled &= ~(1 << irq_idx);
565 			/* Enable the CA1 interrupt when no slot is disabled. */
566 			if (!nubus_disabled)
567 				via2[gIER] = IER_SET_BIT(1);
568 			break;
569 		case MAC_VIA_IIci:
570 			/* On RBV, enable the slot interrupt.
571 			 * SIER works like IER.
572 			 */
573 			via2[rSIER] = IER_SET_BIT(irq_idx);
574 			break;
575 		case MAC_VIA_QUADRA:
576 			/* Make the port A line an input to enable the slot irq.
577 			 * But not on PowerBooks, that's ADB.
578 			 */
579 			if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
580 			    (macintosh_config->adb_type != MAC_ADB_PB2))
581 				via2[vDirA] &= ~(1 << irq_idx);
582 			break;
583 		}
584 	}
585 }
586 
587 void via_irq_disable(int irq) {
588 	int irq_src	= IRQ_SRC(irq);
589 	int irq_idx	= IRQ_IDX(irq);
590 
591 #ifdef DEBUG_IRQUSE
592 	printk(KERN_DEBUG "via_irq_disable(%d)\n", irq);
593 #endif
594 
595 	if (irq_src == 1) {
596 		via1[vIER] = IER_CLR_BIT(irq_idx);
597 	} else if (irq_src == 2) {
598 		via2[gIER] = IER_CLR_BIT(irq_idx);
599 	} else if (irq_src == 7) {
600 		switch (macintosh_config->via_type) {
601 		case MAC_VIA_II:
602 			nubus_disabled |= 1 << irq_idx;
603 			if (nubus_disabled)
604 				via2[gIER] = IER_CLR_BIT(1);
605 			break;
606 		case MAC_VIA_IIci:
607 			via2[rSIER] = IER_CLR_BIT(irq_idx);
608 			break;
609 		case MAC_VIA_QUADRA:
610 			if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
611 			    (macintosh_config->adb_type != MAC_ADB_PB2))
612 				via2[vDirA] |= 1 << irq_idx;
613 			break;
614 		}
615 	}
616 }
617 
618 void via_irq_clear(int irq) {
619 	int irq_src	= IRQ_SRC(irq);
620 	int irq_idx	= IRQ_IDX(irq);
621 	int irq_bit	= 1 << irq_idx;
622 
623 	if (irq_src == 1) {
624 		via1[vIFR] = irq_bit;
625 	} else if (irq_src == 2) {
626 		via2[gIFR] = irq_bit | rbv_clear;
627 	} else if (irq_src == 7) {
628 		/* FIXME: There is no way to clear an individual nubus slot
629 		 * IRQ flag, other than getting the device to do it.
630 		 */
631 	}
632 }
633 
634 /*
635  * Returns nonzero if an interrupt is pending on the given
636  * VIA/IRQ combination.
637  */
638 
639 int via_irq_pending(int irq)
640 {
641 	int irq_src	= IRQ_SRC(irq);
642 	int irq_idx	= IRQ_IDX(irq);
643 	int irq_bit	= 1 << irq_idx;
644 
645 	if (irq_src == 1) {
646 		return via1[vIFR] & irq_bit;
647 	} else if (irq_src == 2) {
648 		return via2[gIFR] & irq_bit;
649 	} else if (irq_src == 7) {
650 		/* Always 0 for MAC_VIA_QUADRA if the slot irq is disabled. */
651 		return ~via2[gBufA] & irq_bit;
652 	}
653 	return 0;
654 }
655