xref: /netbsd-src/sys/arch/arc/isa/isabus.c (revision fad4c9f71477ae11cea2ee75ec82151ac770a534)
1 /*	$NetBSD: isabus.c,v 1.35 2006/06/25 16:46:15 tsutsui Exp $	*/
2 /*	$OpenBSD: isabus.c,v 1.15 1998/03/16 09:38:46 pefo Exp $	*/
3 /*	NetBSD: isa.c,v 1.33 1995/06/28 04:30:51 cgd Exp 	*/
4 
5 /*-
6  * Copyright (c) 1990 The Regents of the University of California.
7  * All rights reserved.
8  *
9  * This code is derived from software contributed to Berkeley by
10  * William Jolitz and Don Ahn.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  *	@(#)isa.c	7.2 (Berkeley) 5/12/91
37  */
38 /*-
39  * Copyright (c) 1995 Per Fogelstrom
40  * Copyright (c) 1993, 1994 Charles M. Hannum.
41  *
42  * This code is derived from software contributed to Berkeley by
43  * William Jolitz and Don Ahn.
44  *
45  * Redistribution and use in source and binary forms, with or without
46  * modification, are permitted provided that the following conditions
47  * are met:
48  * 1. Redistributions of source code must retain the above copyright
49  *    notice, this list of conditions and the following disclaimer.
50  * 2. Redistributions in binary form must reproduce the above copyright
51  *    notice, this list of conditions and the following disclaimer in the
52  *    documentation and/or other materials provided with the distribution.
53  * 3. All advertising materials mentioning features or use of this software
54  *    must display the following acknowledgement:
55  *	This product includes software developed by the University of
56  *	California, Berkeley and its contributors.
57  * 4. Neither the name of the University nor the names of its contributors
58  *    may be used to endorse or promote products derived from this software
59  *    without specific prior written permission.
60  *
61  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
62  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
63  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
64  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
65  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
66  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
67  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
68  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
69  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
70  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
71  * SUCH DAMAGE.
72  *
73  *	@(#)isa.c	7.2 (Berkeley) 5/12/91
74  */
75 /*
76  * Mach Operating System
77  * Copyright (c) 1991,1990,1989 Carnegie Mellon University
78  * All Rights Reserved.
79  *
80  * Permission to use, copy, modify and distribute this software and its
81  * documentation is hereby granted, provided that both the copyright
82  * notice and this permission notice appear in all copies of the
83  * software, derivative works or modified versions, and any portions
84  * thereof, and that both notices appear in supporting documentation.
85  *
86  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
87  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
88  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
89  *
90  * Carnegie Mellon requests users of this software to return to
91  *
92  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
93  *  School of Computer Science
94  *  Carnegie Mellon University
95  *  Pittsburgh PA 15213-3890
96  *
97  * any improvements or extensions that they make and grant Carnegie Mellon
98  * the rights to redistribute these changes.
99  */
100 /*
101   Copyright 1988, 1989 by Intel Corporation, Santa Clara, California.
102 
103 		All Rights Reserved
104 
105 Permission to use, copy, modify, and distribute this software and
106 its documentation for any purpose and without fee is hereby
107 granted, provided that the above copyright notice appears in all
108 copies and that both the copyright notice and this permission notice
109 appear in supporting documentation, and that the name of Intel
110 not be used in advertising or publicity pertaining to distribution
111 of the software without specific, written prior permission.
112 
113 INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
114 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
115 IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
116 CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
117 LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
118 NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
119 WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
120 */
121 
122 #include <sys/cdefs.h>
123 __KERNEL_RCSID(0, "$NetBSD: isabus.c,v 1.35 2006/06/25 16:46:15 tsutsui Exp $");
124 
125 #include <sys/param.h>
126 #include <sys/proc.h>
127 #include <sys/user.h>
128 #include <sys/systm.h>
129 #include <sys/callout.h>
130 #include <sys/time.h>
131 #include <sys/kernel.h>
132 #include <sys/device.h>
133 #include <sys/malloc.h>
134 #include <sys/extent.h>
135 
136 #include <uvm/uvm_extern.h>
137 
138 #include <machine/cpu.h>
139 #include <machine/pio.h>
140 #include <machine/autoconf.h>
141 #include <machine/intr.h>
142 
143 #include <mips/locore.h>
144 
145 #include <dev/ic/i8253reg.h>
146 #include <dev/isa/isareg.h>
147 #include <dev/isa/isavar.h>
148 #include <arc/isa/isabrvar.h>
149 #include <arc/isa/spkrreg.h>
150 
151 #include <arc/arc/timervar.h>
152 
153 static int beeping;
154 static struct callout sysbeep_ch = CALLOUT_INITIALIZER;
155 
156 static long isa_mem_ex_storage[EXTENT_FIXED_STORAGE_SIZE(16) / sizeof(long)];
157 static long isa_io_ex_storage[EXTENT_FIXED_STORAGE_SIZE(16) / sizeof(long)];
158 
159 #define	IRQ_SLAVE	2
160 
161 /* Definition of the driver for autoconfig. */
162 int	isabrprint(void *, const char *);
163 
164 extern struct arc_bus_space arc_bus_io, arc_bus_mem;
165 
166 void	isabr_attach_hook(struct device *, struct device *,
167 			struct isabus_attach_args *);
168 const struct evcnt *isabr_intr_evcnt(isa_chipset_tag_t, int);
169 void	*isabr_intr_establish(isa_chipset_tag_t, int, int, int,
170 			int (*)(void *), void *);
171 void	isabr_intr_disestablish(isa_chipset_tag_t, void*);
172 uint32_t isabr_iointr(uint32_t, struct clockframe *);
173 void	isabr_initicu(void);
174 void	intr_calculatemasks(void);
175 int	fakeintr(void *a);
176 
177 struct isabr_config *isabr_conf = NULL;
178 uint32_t imask[_IPL_N];	/* XXX */
179 
180 void
181 isabrattach(struct isabr_softc *sc)
182 {
183 	struct isabus_attach_args iba;
184 
185 	if (isabr_conf == NULL)
186 		panic("isabr_conf isn't initialized");
187 
188 	printf("\n");
189 
190 	/* Initialize interrupt controller */
191 	isabr_initicu();
192 
193 	sc->arc_isa_cs.ic_attach_hook = isabr_attach_hook;
194 	sc->arc_isa_cs.ic_intr_evcnt = isabr_intr_evcnt;
195 	sc->arc_isa_cs.ic_intr_establish = isabr_intr_establish;
196 	sc->arc_isa_cs.ic_intr_disestablish = isabr_intr_disestablish;
197 
198 	arc_bus_space_init_extent(&arc_bus_mem, (caddr_t)isa_mem_ex_storage,
199 	    sizeof(isa_mem_ex_storage));
200 	arc_bus_space_init_extent(&arc_bus_io, (caddr_t)isa_io_ex_storage,
201 	    sizeof(isa_io_ex_storage));
202 
203 	iba.iba_iot = &arc_bus_io;
204 	iba.iba_memt = &arc_bus_mem;
205 	iba.iba_dmat = &sc->sc_dmat;
206 	iba.iba_ic = &sc->arc_isa_cs;
207 	config_found_ia(&sc->sc_dev, "isabus", &iba, isabrprint);
208 }
209 
210 int
211 isabrprint(void *aux, const char *pnp)
212 {
213 
214         if (pnp)
215                 aprint_normal("isa at %s", pnp);
216         aprint_verbose(" isa_io_base 0x%lx isa_mem_base 0x%lx",
217 		arc_bus_io.bs_vbase, arc_bus_mem.bs_vbase);
218         return (UNCONF);
219 }
220 
221 
222 /*
223  *	Interrupt system driver code
224  *	============================
225  */
226 #define LEGAL_IRQ(x)    ((x) >= 0 && (x) < ICU_LEN && (x) != 2)
227 
228 int	imen;
229 int	intrtype[ICU_LEN], intrmask[ICU_LEN], intrlevel[ICU_LEN];
230 struct isa_intrhand *isa_intrhand[ICU_LEN];
231 
232 int fakeintr(void *a)
233 {
234 
235 	return 0;
236 }
237 
238 /*
239  * Recalculate the interrupt masks from scratch.
240  * We could code special registry and deregistry versions of this function that
241  * would be faster, but the code would be nastier, and we don't expect this to
242  * happen very much anyway.
243  */
244 void
245 intr_calculatemasks(void)
246 {
247 	int irq, level;
248 	struct isa_intrhand *q;
249 
250 	/* First, figure out which levels each IRQ uses. */
251 	for (irq = 0; irq < ICU_LEN; irq++) {
252 		int levels = 0;
253 		for (q = isa_intrhand[irq]; q; q = q->ih_next)
254 			levels |= 1 << q->ih_level;
255 		intrlevel[irq] = levels;
256 	}
257 
258 	/* Then figure out which IRQs use each level. */
259 	for (level = 0; level < _IPL_N; level++) {
260 		int irqs = 0;
261 		for (irq = 0; irq < ICU_LEN; irq++)
262 			if (intrlevel[irq] & (1 << level))
263 				irqs |= 1 << irq;
264 		imask[level] = irqs;
265 	}
266 
267 	imask[IPL_NONE] = 0;
268 
269 	imask[IPL_SOFT] |= imask[IPL_NONE];
270 	imask[IPL_SOFTCLOCK] |= imask[IPL_SOFT];
271 	imask[IPL_SOFTNET] |= imask[IPL_SOFTCLOCK];
272 	imask[IPL_SOFTSERIAL] |= imask[IPL_SOFTNET];
273 
274 	/*
275 	 * Enforce a hierarchy that gives slow devices a better chance at not
276 	 * dropping data.
277 	 */
278 	imask[IPL_BIO] |= imask[IPL_SOFTSERIAL];
279 	imask[IPL_NET] |= imask[IPL_BIO];
280 	imask[IPL_TTY] |= imask[IPL_NET];
281 
282 	/*
283 	 * Since run queues may be manipulated by both the statclock and tty,
284 	 * network, and diskdrivers, clock > tty.
285 	 */
286 	imask[IPL_CLOCK] |= imask[IPL_TTY];
287 	imask[IPL_STATCLOCK] |= imask[IPL_CLOCK];
288 
289 	/*
290 	 * IPL_HIGH must block everything that can manipulate a run queue.
291 	 */
292 	imask[IPL_HIGH] |= imask[IPL_STATCLOCK];
293 
294 	/* And eventually calculate the complete masks. */
295 	for (irq = 0; irq < ICU_LEN; irq++) {
296 		int irqs = 1 << irq;
297 		for (q = isa_intrhand[irq]; q; q = q->ih_next)
298 			irqs |= imask[q->ih_level];
299 		intrmask[irq] = irqs;
300 	}
301 
302 	/* Lastly, determine which IRQs are actually in use. */
303 	{
304 		int irqs = 0;
305 		for (irq = 0; irq < ICU_LEN; irq++)
306 			if (isa_intrhand[irq])
307 				irqs |= 1 << irq;
308 		if (irqs >= 0x100) /* any IRQs >= 8 in use */
309 			irqs |= 1 << IRQ_SLAVE;
310 		imen = ~irqs;
311 		isa_outb(IO_ICU1 + 1, imen);
312 		isa_outb(IO_ICU2 + 1, imen >> 8);
313 	}
314 }
315 
316 void
317 isabr_attach_hook(struct device *parent, struct device *self,
318     struct isabus_attach_args *iba)
319 {
320 
321 	/* Nothing to do. */
322 }
323 
324 const struct evcnt *
325 isabr_intr_evcnt(isa_chipset_tag_t ic, int irq)
326 {
327 
328 	/* XXX for now, no evcnt parent reported */
329 	return NULL;
330 }
331 
332 /*
333  *	Establish a ISA bus interrupt.
334  */
335 void *
336 isabr_intr_establish(isa_chipset_tag_t ic, int irq, int type, int level,
337     int (*ih_fun)(void *), void *ih_arg)
338 {
339 	struct isa_intrhand **p, *q, *ih;
340 	static struct isa_intrhand fakehand = {NULL, fakeintr};
341 
342 	/* no point in sleeping unless someone can free memory. */
343 	ih = malloc(sizeof *ih, M_DEVBUF, cold ? M_NOWAIT : M_WAITOK);
344 	if (ih == NULL)
345 		panic("isa_intr_establish: can't malloc handler info");
346 
347 	if (!LEGAL_IRQ(irq) || type == IST_NONE)
348 		panic("intr_establish: bogus irq or type");
349 
350 	switch (intrtype[irq]) {
351 	case IST_NONE:
352 		intrtype[irq] = type;
353 		break;
354 	case IST_EDGE:
355 	case IST_LEVEL:
356 		if (type == intrtype[irq])
357 			break;
358 	case IST_PULSE:
359 		if (type != IST_NONE)
360 			panic("intr_establish: can't share %s with %s",
361 			    isa_intr_typename(intrtype[irq]),
362 			    isa_intr_typename(type));
363 		break;
364 	}
365 
366 	/*
367 	 * Figure out where to put the handler.
368 	 * This is O(N^2), but we want to preserve the order, and N is
369 	 * generally small.
370 	 */
371 	for (p = &isa_intrhand[irq]; (q = *p) != NULL; p = &q->ih_next)
372 		;
373 
374 	/*
375 	 * Actually install a fake handler momentarily, since we might be doing
376 	 * this with interrupts enabled and don't want the real routine called
377 	 * until masking is set up.
378 	 */
379 	fakehand.ih_level = level;
380 	*p = &fakehand;
381 
382 	intr_calculatemasks();
383 
384 	/*
385 	 * Poke the real handler in now.
386 	 */
387 	ih->ih_fun = ih_fun;
388 	ih->ih_arg = ih_arg;
389 	ih->ih_count = 0;
390 	ih->ih_next = NULL;
391 	ih->ih_level = level;
392 	ih->ih_irq = irq;
393 	snprintf(ih->ih_evname, sizeof(ih->ih_evname), "irq %d", irq);
394 	evcnt_attach_dynamic(&ih->ih_evcnt, EVCNT_TYPE_INTR, NULL, "isa",
395 	    ih->ih_evname);
396 	*p = ih;
397 
398 	return ih;
399 }
400 
401 void
402 isabr_intr_disestablish(isa_chipset_tag_t ic, void *arg)
403 {
404 
405 }
406 
407 /*
408  *	Process an interrupt from the ISA bus.
409  */
410 uint32_t
411 isabr_iointr(uint32_t mask, struct clockframe *cf)
412 {
413 	struct isa_intrhand *ih;
414 	int isa_vector;
415 	int o_imen;
416 
417 	isa_vector = (*isabr_conf->ic_intr_status)();
418 	if (isa_vector < 0)
419 		return (~0);
420 
421 	o_imen = imen;
422 	imen |= 1 << (isa_vector & (ICU_LEN - 1));
423 	if (isa_vector & 0x08) {
424 		isa_inb(IO_ICU2 + 1);
425 		isa_outb(IO_ICU2 + 1, imen >> 8);
426 		isa_outb(IO_ICU2, 0x60 + (isa_vector & 7));
427 		isa_outb(IO_ICU1, 0x60 + IRQ_SLAVE);
428 	} else {
429 		isa_inb(IO_ICU1 + 1);
430 		isa_outb(IO_ICU1 + 1, imen);
431 		isa_outb(IO_ICU1, 0x60 + isa_vector);
432 	}
433 	ih = isa_intrhand[isa_vector];
434 	if (isa_vector == 0 && ih) {	/* Clock */	/*XXX*/
435 		last_cp0_count = mips3_cp0_count_read();
436 		/* XXX: spllowerclock() not allowed */
437 		cf->sr &= ~MIPS_SR_INT_IE;
438 		if ((*ih->ih_fun)(cf))
439 			ih->ih_evcnt.ev_count++;
440 		ih = ih->ih_next;
441 	}
442 	while (ih) {
443 		if ((*ih->ih_fun)(ih->ih_arg))
444 			ih->ih_evcnt.ev_count++;
445 		ih = ih->ih_next;
446 	}
447 	imen = o_imen;
448 	isa_inb(IO_ICU1 + 1);
449 	isa_inb(IO_ICU2 + 1);
450 	isa_outb(IO_ICU1 + 1, imen);
451 	isa_outb(IO_ICU2 + 1, imen >> 8);
452 
453 	return ~MIPS_INT_MASK_2;
454 }
455 
456 
457 /*
458  * Initialize the Interrupt controller logic.
459  */
460 void
461 isabr_initicu(void)
462 {
463 
464 	int i;
465 
466 	for (i = 0; i < ICU_LEN; i++) {
467 		switch (i) {
468 		case 2:
469 		case 8:
470 			intrtype[i] = IST_EDGE;
471 			break;
472 		default:
473 			intrtype[i] = IST_NONE;
474 			break;
475 		}
476 	}
477 
478 	isa_outb(IO_ICU1, 0x11);		/* reset; program device, four bytes */
479 	isa_outb(IO_ICU1+1, 0);			/* starting at this vector index */
480 	isa_outb(IO_ICU1+1, 1 << IRQ_SLAVE);	/* slave on line 2 */
481 	isa_outb(IO_ICU1+1, 1);			/* 8086 mode */
482 	isa_outb(IO_ICU1+1, 0xff);		/* leave interrupts masked */
483 	isa_outb(IO_ICU1, 0x68);		/* special mask mode (if available) */
484 	isa_outb(IO_ICU1, 0x0a);		/* Read IRR by default. */
485 #ifdef REORDER_IRQ
486 	isa_outb(IO_ICU1, 0xc0 | (3 - 1));	/* pri order 3-7, 0-2 (com2 first) */
487 #endif
488 
489 	isa_outb(IO_ICU2, 0x11);		/* reset; program device, four bytes */
490 	isa_outb(IO_ICU2+1, 8);			/* staring at this vector index */
491 	isa_outb(IO_ICU2+1, IRQ_SLAVE);
492 	isa_outb(IO_ICU2+1, 1);			/* 8086 mode */
493 	isa_outb(IO_ICU2+1, 0xff);		/* leave interrupts masked */
494 	isa_outb(IO_ICU2, 0x68);		/* special mask mode (if available) */
495 	isa_outb(IO_ICU2, 0x0a);		/* Read IRR by default. */
496 }
497 
498 
499 /*
500  *	SPEAKER BEEPER...
501  */
502 void
503 sysbeepstop(void *arg)
504 {
505 	int s;
506 
507 	/* disable counter 2 */
508 	s = splhigh();
509 	isa_outb(PITAUX_PORT, isa_inb(PITAUX_PORT) & ~PIT_SPKR);
510 	splx(s);
511 	beeping = 0;
512 }
513 
514 void
515 sysbeep(int pitch, int period)
516 {
517 	static int last_pitch, last_period;
518 	int s;
519 
520 	if (cold)
521 		return;		/* Can't beep yet. */
522 
523 	if (beeping)
524 		callout_stop(&sysbeep_ch);
525 	if (!beeping || last_pitch != pitch) {
526 		s = splhigh();
527 		isa_outb(IO_TIMER1 + TIMER_MODE,
528 		    TIMER_SEL2 | TIMER_16BIT | TIMER_SQWAVE);
529 		isa_outb(IO_TIMER1 + TIMER_CNTR2, TIMER_DIV(pitch) % 256);
530 		isa_outb(IO_TIMER1 + TIMER_CNTR2, TIMER_DIV(pitch) / 256);
531 		isa_outb(PITAUX_PORT, isa_inb(PITAUX_PORT) | PIT_SPKR);
532 		splx(s);
533 	}
534 	last_pitch = pitch;
535 	beeping = last_period = period;
536 	callout_reset(&sysbeep_ch, period, sysbeepstop, NULL);
537 }
538 
539 int
540 isa_intr_alloc(isa_chipset_tag_t c, int mask, int type, int *irq_p)
541 {
542 	int irq;
543 	int maybe_irq = -1;
544 	int shared_depth = 0;
545 	mask &= 0x8b28; /* choose from 3, 5, 8, 9, 11, 15 XXX */
546 	for (irq = 0; mask != 0; mask >>= 1, irq++) {
547 		if ((mask & 1) == 0)
548 			continue;
549 		if (intrtype[irq] == IST_NONE) {
550 			*irq_p = irq;
551 			return 0;
552 		}
553 		/* Level interrupts can be shared */
554 		if (type == IST_LEVEL && intrtype[irq] == IST_LEVEL) {
555 			struct isa_intrhand *ih = isa_intrhand[irq];
556 			int depth;
557 			if (maybe_irq == -1) {
558  				maybe_irq = irq;
559 				continue;
560 			}
561 			for (depth = 0; ih != NULL; ih = ih->ih_next)
562 				depth++;
563 			if (depth < shared_depth) {
564 				maybe_irq = irq;
565 				shared_depth = depth;
566 			}
567 		}
568 	}
569 	if (maybe_irq != -1) {
570 		*irq_p = maybe_irq;
571 		return 0;
572 	}
573 	return 1;
574 }
575