1 /* $NetBSD: isabus.c,v 1.47 2009/12/16 23:19:07 matt 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 1.47 2009/12/16 23:19:07 matt Exp $"); 124 125 #include <sys/param.h> 126 #include <sys/proc.h> 127 #include <sys/systm.h> 128 #include <sys/callout.h> 129 #include <sys/time.h> 130 #include <sys/kernel.h> 131 #include <sys/device.h> 132 #include <sys/malloc.h> 133 #include <sys/extent.h> 134 135 #include <uvm/uvm_extern.h> 136 137 #include <machine/cpu.h> 138 #include <machine/pio.h> 139 #include <machine/autoconf.h> 140 #include <machine/intr.h> 141 142 #include <mips/locore.h> 143 144 #include <dev/ic/i8253reg.h> 145 #include <dev/ic/i8259reg.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 callout_t sysbeep_ch; 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 static int isabrprint(void *, const char *); 163 164 extern struct arc_bus_space arc_bus_io, arc_bus_mem; 165 166 static void isabr_attach_hook(device_t , device_t, 167 struct isabus_attach_args *); 168 static void isabr_detach_hook(isa_chipset_tag_t, device_t); 169 static const struct evcnt *isabr_intr_evcnt(isa_chipset_tag_t, int); 170 static void *isabr_intr_establish(isa_chipset_tag_t, int, int, int, 171 int (*)(void *), void *); 172 static void isabr_intr_disestablish(isa_chipset_tag_t, void*); 173 static void isabr_initicu(void); 174 static void intr_calculatemasks(void); 175 static 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 callout_init(&sysbeep_ch, 0); 186 187 if (isabr_conf == NULL) 188 panic("isabr_conf isn't initialized"); 189 190 aprint_normal("\n"); 191 192 /* Initialize interrupt controller */ 193 isabr_initicu(); 194 195 sc->arc_isa_cs.ic_attach_hook = isabr_attach_hook; 196 sc->arc_isa_cs.ic_detach_hook = isabr_detach_hook; 197 sc->arc_isa_cs.ic_intr_evcnt = isabr_intr_evcnt; 198 sc->arc_isa_cs.ic_intr_establish = isabr_intr_establish; 199 sc->arc_isa_cs.ic_intr_disestablish = isabr_intr_disestablish; 200 201 arc_bus_space_init_extent(&arc_bus_mem, (void *)isa_mem_ex_storage, 202 sizeof(isa_mem_ex_storage)); 203 arc_bus_space_init_extent(&arc_bus_io, (void *)isa_io_ex_storage, 204 sizeof(isa_io_ex_storage)); 205 206 iba.iba_iot = &arc_bus_io; 207 iba.iba_memt = &arc_bus_mem; 208 iba.iba_dmat = &sc->sc_dmat; 209 iba.iba_ic = &sc->arc_isa_cs; 210 config_found_ia(sc->sc_dev, "isabus", &iba, isabrprint); 211 } 212 213 static int 214 isabrprint(void *aux, const char *pnp) 215 { 216 217 if (pnp) 218 aprint_normal("isa at %s", pnp); 219 aprint_verbose(" isa_io_base 0x%"PRIxVADDR" isa_mem_base 0x%"PRIxVADDR, 220 arc_bus_io.bs_vbase, arc_bus_mem.bs_vbase); 221 return UNCONF; 222 } 223 224 225 /* 226 * Interrupt system driver code 227 * ============================ 228 */ 229 #define LEGAL_IRQ(x) ((x) >= 0 && (x) < ICU_LEN && (x) != 2) 230 231 int imen; 232 int intrtype[ICU_LEN], intrmask[ICU_LEN], intrlevel[ICU_LEN]; 233 struct isa_intrhand *isa_intrhand[ICU_LEN]; 234 235 static int 236 fakeintr(void *a) 237 { 238 239 return 0; 240 } 241 242 /* 243 * Recalculate the interrupt masks from scratch. 244 * We could code special registry and deregistry versions of this function that 245 * would be faster, but the code would be nastier, and we don't expect this to 246 * happen very much anyway. 247 */ 248 static void 249 intr_calculatemasks(void) 250 { 251 int irq, level; 252 struct isa_intrhand *q; 253 254 /* First, figure out which levels each IRQ uses. */ 255 for (irq = 0; irq < ICU_LEN; irq++) { 256 int levels = 0; 257 for (q = isa_intrhand[irq]; q; q = q->ih_next) 258 levels |= 1 << q->ih_level; 259 intrlevel[irq] = levels; 260 } 261 262 /* Then figure out which IRQs use each level. */ 263 for (level = 0; level < _IPL_N; level++) { 264 int irqs = 0; 265 for (irq = 0; irq < ICU_LEN; irq++) 266 if (intrlevel[irq] & (1 << level)) 267 irqs |= 1 << irq; 268 imask[level] = irqs; 269 } 270 271 imask[IPL_NONE] = 0; 272 273 imask[IPL_SOFTCLOCK] |= imask[IPL_NONE]; 274 imask[IPL_SOFTNET] |= imask[IPL_SOFTCLOCK]; 275 276 /* 277 * Enforce a hierarchy that gives slow devices a better chance at not 278 * dropping data. 279 */ 280 imask[IPL_VM] |= imask[IPL_SOFTNET]; 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_SCHED] |= imask[IPL_VM]; 287 288 /* And eventually calculate the complete masks. */ 289 for (irq = 0; irq < ICU_LEN; irq++) { 290 int irqs = 1 << irq; 291 for (q = isa_intrhand[irq]; q; q = q->ih_next) 292 irqs |= imask[q->ih_level]; 293 intrmask[irq] = irqs; 294 } 295 296 /* Lastly, determine which IRQs are actually in use. */ 297 { 298 int irqs = 0; 299 for (irq = 0; irq < ICU_LEN; irq++) 300 if (isa_intrhand[irq]) 301 irqs |= 1 << irq; 302 if (irqs >= 0x100) /* any IRQs >= 8 in use */ 303 irqs |= 1 << IRQ_SLAVE; 304 imen = ~irqs; 305 isa_outb(IO_ICU1 + PIC_OCW1, imen); 306 isa_outb(IO_ICU2 + PIC_OCW1, imen >> 8); 307 } 308 } 309 310 static void 311 isabr_attach_hook(struct device *parent, struct device *self, 312 struct isabus_attach_args *iba) 313 { 314 315 /* Nothing to do. */ 316 } 317 318 static void 319 isabr_detach_hook(isa_chipset_tag_t ic, device_t self) 320 { 321 322 /* Nothing to do. */ 323 } 324 325 static const struct evcnt * 326 isabr_intr_evcnt(isa_chipset_tag_t ic, int irq) 327 { 328 329 /* XXX for now, no evcnt parent reported */ 330 return NULL; 331 } 332 333 /* 334 * Establish a ISA bus interrupt. 335 */ 336 static void * 337 isabr_intr_establish(isa_chipset_tag_t ic, int irq, int type, int level, 338 int (*ih_fun)(void *), void *ih_arg) 339 { 340 struct isa_intrhand **p, *q, *ih; 341 static struct isa_intrhand fakehand = {NULL, fakeintr}; 342 343 /* no point in sleeping unless someone can free memory. */ 344 ih = malloc(sizeof *ih, M_DEVBUF, cold ? M_NOWAIT : M_WAITOK); 345 if (ih == NULL) 346 panic("isa_intr_establish: can't malloc handler info"); 347 348 if (!LEGAL_IRQ(irq) || type == IST_NONE) 349 panic("intr_establish: bogus irq or type"); 350 351 switch (intrtype[irq]) { 352 case IST_NONE: 353 intrtype[irq] = type; 354 break; 355 case IST_EDGE: 356 case IST_LEVEL: 357 if (type == intrtype[irq]) 358 break; 359 case IST_PULSE: 360 if (type != IST_NONE) 361 panic("intr_establish: can't share %s with %s", 362 isa_intr_typename(intrtype[irq]), 363 isa_intr_typename(type)); 364 break; 365 } 366 367 /* 368 * Figure out where to put the handler. 369 * This is O(N^2), but we want to preserve the order, and N is 370 * generally small. 371 */ 372 for (p = &isa_intrhand[irq]; (q = *p) != NULL; p = &q->ih_next) 373 ; 374 375 /* 376 * Actually install a fake handler momentarily, since we might be doing 377 * this with interrupts enabled and don't want the real routine called 378 * until masking is set up. 379 */ 380 fakehand.ih_level = level; 381 *p = &fakehand; 382 383 intr_calculatemasks(); 384 385 /* 386 * Poke the real handler in now. 387 */ 388 ih->ih_fun = ih_fun; 389 ih->ih_arg = ih_arg; 390 ih->ih_count = 0; 391 ih->ih_next = NULL; 392 ih->ih_level = level; 393 ih->ih_irq = irq; 394 snprintf(ih->ih_evname, sizeof(ih->ih_evname), "irq %d", irq); 395 evcnt_attach_dynamic(&ih->ih_evcnt, EVCNT_TYPE_INTR, NULL, "isa", 396 ih->ih_evname); 397 *p = ih; 398 399 return ih; 400 } 401 402 static void 403 isabr_intr_disestablish(isa_chipset_tag_t ic, void *arg) 404 { 405 406 } 407 408 /* 409 * Process an interrupt from the ISA bus. 410 */ 411 uint32_t 412 isabr_iointr(uint32_t mask, struct clockframe *cf) 413 { 414 struct isa_intrhand *ih; 415 int isa_vector; 416 int o_imen; 417 418 isa_vector = (*isabr_conf->ic_intr_status)(); 419 if (isa_vector < 0) 420 return 0; 421 422 o_imen = imen; 423 imen |= 1 << (isa_vector & (ICU_LEN - 1)); 424 if (isa_vector & 0x08) { 425 isa_inb(IO_ICU2 + PIC_OCW1); 426 isa_outb(IO_ICU2 + PIC_OCW1, imen >> 8); 427 isa_outb(IO_ICU2 + PIC_OCW2, 428 OCW2_SELECT | OCW2_EOI | OCW2_SL | 429 OCW2_ILS((isa_vector & 7))); 430 isa_outb(IO_ICU1, 431 OCW2_SELECT | OCW2_EOI | OCW2_SL | IRQ_SLAVE); 432 } else { 433 isa_inb(IO_ICU1 + PIC_OCW1); 434 isa_outb(IO_ICU1 + PIC_OCW1, imen); 435 isa_outb(IO_ICU1 + PIC_OCW2, 436 OCW2_SELECT | OCW2_EOI | OCW2_SL | OCW2_ILS(isa_vector)); 437 } 438 ih = isa_intrhand[isa_vector]; 439 if (isa_vector == 0 && ih) { /* Clock */ /*XXX*/ 440 last_cp0_count = mips3_cp0_count_read(); 441 /* XXX: spllowerclock() not allowed */ 442 cf->sr &= ~MIPS_SR_INT_IE; 443 if ((*ih->ih_fun)(cf)) 444 ih->ih_evcnt.ev_count++; 445 ih = ih->ih_next; 446 } 447 while (ih) { 448 if ((*ih->ih_fun)(ih->ih_arg)) 449 ih->ih_evcnt.ev_count++; 450 ih = ih->ih_next; 451 } 452 imen = o_imen; 453 isa_inb(IO_ICU1 + PIC_OCW1); 454 isa_inb(IO_ICU2 + PIC_OCW1); 455 isa_outb(IO_ICU1 + PIC_OCW1, imen); 456 isa_outb(IO_ICU2 + PIC_OCW1, imen >> 8); 457 458 return MIPS_INT_MASK_2; 459 } 460 461 462 /* 463 * Initialize the Interrupt controller logic. 464 */ 465 static void 466 isabr_initicu(void) 467 { 468 469 int i; 470 471 for (i = 0; i < ICU_LEN; i++) { 472 switch (i) { 473 case 2: 474 case 8: 475 intrtype[i] = IST_EDGE; 476 break; 477 default: 478 intrtype[i] = IST_NONE; 479 break; 480 } 481 } 482 483 /* reset; program device, four bytes */ 484 isa_outb(IO_ICU1 + PIC_ICW1, ICW1_SELECT | ICW1_IC4); 485 /* starting at this vector index */ 486 isa_outb(IO_ICU1 + PIC_ICW2, 0); 487 /* slave on line 2 */ 488 isa_outb(IO_ICU1 + PIC_ICW3, ICW3_CASCADE(IRQ_SLAVE)); 489 /* 8086 mode */ 490 isa_outb(IO_ICU1 + PIC_ICW4, ICW4_8086); 491 492 /* leave interrupts masked */ 493 isa_outb(IO_ICU1 + PIC_OCW1, 0xff); 494 495 /* special mask mode (if available) */ 496 isa_outb(IO_ICU1 + PIC_OCW3, OCW3_SELECT | OCW3_SSMM | OCW3_SMM); 497 /* Read IRR by default. */ 498 isa_outb(IO_ICU1 + PIC_OCW3, OCW3_SELECT | OCW3_RR); 499 #ifdef REORDER_IRQ 500 /* pri order 3-7, 0-2 (com2 first) */ 501 isa_outb(IO_ICU1 + PIC_OCW2, 502 OCW2_SELECT | OCW2_R | OCW2_SL OCW2_ILS(3 - 1)); 503 #endif 504 505 /* reset; program device, four bytes */ 506 isa_outb(IO_ICU2 + PIC_ICW1, ICW1_SELECT | ICW1_IC4); 507 /* staring at this vector index */ 508 isa_outb(IO_ICU2 + PIC_ICW2, 8); 509 /* slave connected to line 2 of master */ 510 isa_outb(IO_ICU2 + PIC_ICW3, ICW3_SIC(IRQ_SLAVE)); 511 /* 8086 mode */ 512 isa_outb(IO_ICU2 + PIC_ICW4, ICW4_8086); 513 514 /* leave interrupts masked */ 515 isa_outb(IO_ICU2 + PIC_OCW1, 0xff); 516 517 /* special mask mode (if available) */ 518 isa_outb(IO_ICU2 + PIC_OCW3, OCW3_SELECT | OCW3_SSMM | OCW3_SMM); 519 /* Read IRR by default. */ 520 isa_outb(IO_ICU2 + PIC_OCW3, OCW3_SELECT | OCW3_RR); 521 } 522 523 524 /* 525 * SPEAKER BEEPER... 526 */ 527 void 528 sysbeepstop(void *arg) 529 { 530 int s; 531 532 /* disable counter 2 */ 533 s = splhigh(); 534 isa_outb(PITAUX_PORT, isa_inb(PITAUX_PORT) & ~PIT_SPKR); 535 splx(s); 536 beeping = 0; 537 } 538 539 void 540 sysbeep(int pitch, int period) 541 { 542 static int last_pitch, last_period; 543 int s; 544 545 if (cold) 546 return; /* Can't beep yet. */ 547 548 if (beeping) 549 callout_stop(&sysbeep_ch); 550 if (!beeping || last_pitch != pitch) { 551 s = splhigh(); 552 isa_outb(IO_TIMER1 + TIMER_MODE, 553 TIMER_SEL2 | TIMER_16BIT | TIMER_SQWAVE); 554 isa_outb(IO_TIMER1 + TIMER_CNTR2, TIMER_DIV(pitch) % 256); 555 isa_outb(IO_TIMER1 + TIMER_CNTR2, TIMER_DIV(pitch) / 256); 556 isa_outb(PITAUX_PORT, isa_inb(PITAUX_PORT) | PIT_SPKR); 557 splx(s); 558 } 559 last_pitch = pitch; 560 beeping = last_period = period; 561 callout_reset(&sysbeep_ch, period, sysbeepstop, NULL); 562 } 563 564 int 565 isa_intr_alloc(isa_chipset_tag_t c, int mask, int type, int *irq_p) 566 { 567 int irq; 568 int maybe_irq = -1; 569 int shared_depth = 0; 570 mask &= 0x8b28; /* choose from 3, 5, 8, 9, 11, 15 XXX */ 571 for (irq = 0; mask != 0; mask >>= 1, irq++) { 572 if ((mask & 1) == 0) 573 continue; 574 if (intrtype[irq] == IST_NONE) { 575 *irq_p = irq; 576 return 0; 577 } 578 /* Level interrupts can be shared */ 579 if (type == IST_LEVEL && intrtype[irq] == IST_LEVEL) { 580 struct isa_intrhand *ih = isa_intrhand[irq]; 581 int depth; 582 if (maybe_irq == -1) { 583 maybe_irq = irq; 584 continue; 585 } 586 for (depth = 0; ih != NULL; ih = ih->ih_next) 587 depth++; 588 if (depth < shared_depth) { 589 maybe_irq = irq; 590 shared_depth = depth; 591 } 592 } 593 } 594 if (maybe_irq != -1) { 595 *irq_p = maybe_irq; 596 return 0; 597 } 598 return 1; 599 } 600