xref: /freebsd/sys/i386/pci/pci_pir.c (revision 6ae1554a5d9b318f8ad53ccc39fa5a961403da73)
1 /*-
2  * Copyright (c) 1997, Stefan Esser <se@freebsd.org>
3  * Copyright (c) 2000, Michael Smith <msmith@freebsd.org>
4  * Copyright (c) 2000, BSDi
5  * Copyright (c) 2004, John Baldwin <jhb@FreeBSD.org>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice unmodified, this list of conditions, and the following
13  *    disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/bus.h>
36 #include <sys/kernel.h>
37 #include <sys/malloc.h>
38 #include <sys/module.h>
39 #include <sys/sysctl.h>
40 #include <vm/vm.h>
41 #include <vm/pmap.h>
42 #include <vm/vm_param.h>
43 #include <machine/md_var.h>
44 #include <dev/pci/pcivar.h>
45 #include <dev/pci/pcireg.h>
46 #include <machine/pci_cfgreg.h>
47 #include <machine/segments.h>
48 #include <machine/pc/bios.h>
49 
50 #define	NUM_ISA_INTERRUPTS	16
51 
52 /*
53  * A link device.  Loosely based on the ACPI PCI link device.  This doesn't
54  * try to support priorities for different ISA interrupts.
55  */
56 struct pci_link {
57 	TAILQ_ENTRY(pci_link) pl_links;
58 	uint8_t		pl_id;
59 	uint8_t		pl_irq;
60 	uint16_t	pl_irqmask;
61 	int		pl_references;
62 	int		pl_routed;
63 };
64 
65 struct pci_link_lookup {
66 	struct pci_link	**pci_link_ptr;
67 	int		bus;
68 	int		device;
69 	int		pin;
70 };
71 
72 struct pci_dev_lookup {
73 	uint8_t		link;
74 	int		bus;
75 	int		device;
76 	int		pin;
77 };
78 
79 typedef void pir_entry_handler(struct PIR_entry *entry,
80     struct PIR_intpin* intpin, void *arg);
81 
82 static void	pci_print_irqmask(u_int16_t irqs);
83 static int	pci_pir_biosroute(int bus, int device, int func, int pin,
84 		    int irq);
85 static int	pci_pir_choose_irq(struct pci_link *pci_link, int irqmask);
86 static void	pci_pir_create_links(struct PIR_entry *entry,
87 		    struct PIR_intpin *intpin, void *arg);
88 static void	pci_pir_dump_links(void);
89 static struct pci_link *pci_pir_find_link(uint8_t link_id);
90 static void	pci_pir_find_link_handler(struct PIR_entry *entry,
91 		    struct PIR_intpin *intpin, void *arg);
92 static void	pci_pir_initial_irqs(struct PIR_entry *entry,
93 		    struct PIR_intpin *intpin, void *arg);
94 static void	pci_pir_parse(void);
95 static uint8_t	pci_pir_search_irq(int bus, int device, int pin);
96 static int	pci_pir_valid_irq(struct pci_link *pci_link, int irq);
97 static void	pci_pir_walk_table(pir_entry_handler *handler, void *arg);
98 
99 static MALLOC_DEFINE(M_PIR, "$PIR", "$PIR structures");
100 
101 static struct PIR_table *pci_route_table;
102 static device_t pir_device;
103 static int pci_route_count, pir_bios_irqs, pir_parsed;
104 static TAILQ_HEAD(, pci_link) pci_links;
105 static int pir_interrupt_weight[NUM_ISA_INTERRUPTS];
106 
107 /* sysctl vars */
108 SYSCTL_DECL(_hw_pci);
109 
110 /* XXX this likely should live in a header file */
111 #ifdef PC98
112 /* IRQs 3, 5, 7, 9, 10, 11, 12, 13 */
113 #define PCI_IRQ_OVERRIDE_MASK 0x3e68
114 #else
115 /* IRQs 3, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15 */
116 #define PCI_IRQ_OVERRIDE_MASK 0xdef8
117 #endif
118 
119 static uint32_t pci_irq_override_mask = PCI_IRQ_OVERRIDE_MASK;
120 SYSCTL_INT(_hw_pci, OID_AUTO, irq_override_mask, CTLFLAG_RDTUN,
121     &pci_irq_override_mask, PCI_IRQ_OVERRIDE_MASK,
122     "Mask of allowed irqs to try to route when it has no good clue about\n"
123     "which irqs it should use.");
124 
125 /*
126  * Look for the interrupt routing table.
127  *
128  * We use PCI BIOS's PIR table if it's available. $PIR is the standard way
129  * to do this.  Sadly, some machines are not standards conforming and have
130  * _PIR instead.  We shrug and cope by looking for both.
131  */
132 void
133 pci_pir_open(void)
134 {
135 	struct PIR_table *pt;
136 	uint32_t sigaddr;
137 	int i;
138 	uint8_t ck, *cv;
139 
140 	/* Don't try if we've already found a table. */
141 	if (pci_route_table != NULL)
142 		return;
143 
144 	/* Look for $PIR and then _PIR. */
145 	sigaddr = bios_sigsearch(0, "$PIR", 4, 16, 0);
146 	if (sigaddr == 0)
147 		sigaddr = bios_sigsearch(0, "_PIR", 4, 16, 0);
148 	if (sigaddr == 0)
149 		return;
150 
151 	/* If we found something, check the checksum and length. */
152 	/* XXX - Use pmap_mapdev()? */
153 	pt = (struct PIR_table *)(uintptr_t)BIOS_PADDRTOVADDR(sigaddr);
154 	if (pt->pt_header.ph_length <= sizeof(struct PIR_header))
155 		return;
156 	for (cv = (u_int8_t *)pt, ck = 0, i = 0;
157 	     i < (pt->pt_header.ph_length); i++)
158 		ck += cv[i];
159 	if (ck != 0)
160 		return;
161 
162 	/* Ok, we've got a valid table. */
163 	pci_route_table = pt;
164 	pci_route_count = (pt->pt_header.ph_length -
165 	    sizeof(struct PIR_header)) /
166 	    sizeof(struct PIR_entry);
167 }
168 
169 /*
170  * Find the pci_link structure for a given link ID.
171  */
172 static struct pci_link *
173 pci_pir_find_link(uint8_t link_id)
174 {
175 	struct pci_link *pci_link;
176 
177 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
178 		if (pci_link->pl_id == link_id)
179 			return (pci_link);
180 	}
181 	return (NULL);
182 }
183 
184 /*
185  * Find the link device associated with a PCI device in the table.
186  */
187 static void
188 pci_pir_find_link_handler(struct PIR_entry *entry, struct PIR_intpin *intpin,
189     void *arg)
190 {
191 	struct pci_link_lookup *lookup;
192 
193 	lookup = (struct pci_link_lookup *)arg;
194 	if (entry->pe_bus == lookup->bus &&
195 	    entry->pe_device == lookup->device &&
196 	    intpin - entry->pe_intpin == lookup->pin)
197 		*lookup->pci_link_ptr = pci_pir_find_link(intpin->link);
198 }
199 
200 /*
201  * Check to see if a possible IRQ setting is valid.
202  */
203 static int
204 pci_pir_valid_irq(struct pci_link *pci_link, int irq)
205 {
206 
207 	if (!PCI_INTERRUPT_VALID(irq))
208 		return (0);
209 	return (pci_link->pl_irqmask & (1 << irq));
210 }
211 
212 /*
213  * Walk the $PIR executing the worker function for each valid intpin entry
214  * in the table.  The handler is passed a pointer to both the entry and
215  * the intpin in the entry.
216  */
217 static void
218 pci_pir_walk_table(pir_entry_handler *handler, void *arg)
219 {
220 	struct PIR_entry *entry;
221 	struct PIR_intpin *intpin;
222 	int i, pin;
223 
224 	entry = &pci_route_table->pt_entry[0];
225 	for (i = 0; i < pci_route_count; i++, entry++) {
226 		intpin = &entry->pe_intpin[0];
227 		for (pin = 0; pin < 4; pin++, intpin++)
228 			if (intpin->link != 0)
229 				handler(entry, intpin, arg);
230 	}
231 }
232 
233 static void
234 pci_pir_create_links(struct PIR_entry *entry, struct PIR_intpin *intpin,
235     void *arg)
236 {
237 	struct pci_link *pci_link;
238 
239 	pci_link = pci_pir_find_link(intpin->link);
240 	if (pci_link != NULL) {
241 		pci_link->pl_references++;
242 		if (intpin->irqs != pci_link->pl_irqmask) {
243 			if (bootverbose)
244 				printf(
245 	"$PIR: Entry %d.%d.INT%c has different mask for link %#x, merging\n",
246 				    entry->pe_bus, entry->pe_device,
247 				    (intpin - entry->pe_intpin) + 'A',
248 				    pci_link->pl_id);
249 			pci_link->pl_irqmask &= intpin->irqs;
250 		}
251 	} else {
252 		pci_link = malloc(sizeof(struct pci_link), M_PIR, M_WAITOK);
253 		pci_link->pl_id = intpin->link;
254 		pci_link->pl_irqmask = intpin->irqs;
255 		pci_link->pl_irq = PCI_INVALID_IRQ;
256 		pci_link->pl_references = 1;
257 		pci_link->pl_routed = 0;
258 		TAILQ_INSERT_TAIL(&pci_links, pci_link, pl_links);
259 	}
260 }
261 
262 /*
263  * Look to see if any of the function on the PCI device at bus/device have
264  * an interrupt routed to intpin 'pin' by the BIOS.
265  */
266 static uint8_t
267 pci_pir_search_irq(int bus, int device, int pin)
268 {
269 	uint32_t value;
270 	uint8_t func, maxfunc;
271 
272 	/* See if we have a valid device at function 0. */
273 	value = pci_cfgregread(bus, device, 0, PCIR_HDRTYPE, 1);
274 	if ((value & PCIM_HDRTYPE) > PCI_MAXHDRTYPE)
275 		return (PCI_INVALID_IRQ);
276 	if (value & PCIM_MFDEV)
277 		maxfunc = PCI_FUNCMAX;
278 	else
279 		maxfunc = 0;
280 
281 	/* Scan all possible functions at this device. */
282 	for (func = 0; func <= maxfunc; func++) {
283 		value = pci_cfgregread(bus, device, func, PCIR_DEVVENDOR, 4);
284 		if (value == 0xffffffff)
285 			continue;
286 		value = pci_cfgregread(bus, device, func, PCIR_INTPIN, 1);
287 
288 		/*
289 		 * See if it uses the pin in question.  Note that the passed
290 		 * in pin uses 0 for A, .. 3 for D whereas the intpin
291 		 * register uses 0 for no interrupt, 1 for A, .. 4 for D.
292 		 */
293 		if (value != pin + 1)
294 			continue;
295 		value = pci_cfgregread(bus, device, func, PCIR_INTLINE, 1);
296 		if (bootverbose)
297 			printf(
298 		"$PIR: Found matching pin for %d.%d.INT%c at func %d: %d\n",
299 			    bus, device, pin + 'A', func, value);
300 		if (value != PCI_INVALID_IRQ)
301 			return (value);
302 	}
303 	return (PCI_INVALID_IRQ);
304 }
305 
306 /*
307  * Try to initialize IRQ based on this device's IRQ.
308  */
309 static void
310 pci_pir_initial_irqs(struct PIR_entry *entry, struct PIR_intpin *intpin,
311     void *arg)
312 {
313 	struct pci_link *pci_link;
314 	uint8_t irq, pin;
315 
316 	pin = intpin - entry->pe_intpin;
317 	pci_link = pci_pir_find_link(intpin->link);
318 	irq = pci_pir_search_irq(entry->pe_bus, entry->pe_device, pin);
319 	if (irq == PCI_INVALID_IRQ || irq == pci_link->pl_irq)
320 		return;
321 
322 	/* Don't trust any BIOS IRQs greater than 15. */
323 	if (irq >= NUM_ISA_INTERRUPTS) {
324 		printf(
325 	"$PIR: Ignoring invalid BIOS IRQ %d from %d.%d.INT%c for link %#x\n",
326 		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
327 		    pci_link->pl_id);
328 		return;
329 	}
330 
331 	/*
332 	 * If we don't have an IRQ for this link yet, then we trust the
333 	 * BIOS, even if it seems invalid from the $PIR entries.
334 	 */
335 	if (pci_link->pl_irq == PCI_INVALID_IRQ) {
336 		if (!pci_pir_valid_irq(pci_link, irq))
337 			printf(
338 	"$PIR: Using invalid BIOS IRQ %d from %d.%d.INT%c for link %#x\n",
339 			    irq, entry->pe_bus, entry->pe_device, pin + 'A',
340 			    pci_link->pl_id);
341 		pci_link->pl_irq = irq;
342 		pci_link->pl_routed = 1;
343 		return;
344 	}
345 
346 	/*
347 	 * We have an IRQ and it doesn't match the current IRQ for this
348 	 * link.  If the new IRQ is invalid, then warn about it and ignore
349 	 * it.  If the old IRQ is invalid and the new IRQ is valid, then
350 	 * prefer the new IRQ instead.  If both IRQs are valid, then just
351 	 * use the first one.  Note that if we ever get into this situation
352 	 * we are having to guess which setting the BIOS actually routed.
353 	 * Perhaps we should just give up instead.
354 	 */
355 	if (!pci_pir_valid_irq(pci_link, irq)) {
356 		printf(
357 		"$PIR: BIOS IRQ %d for %d.%d.INT%c is not valid for link %#x\n",
358 		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
359 		    pci_link->pl_id);
360 	} else if (!pci_pir_valid_irq(pci_link, pci_link->pl_irq)) {
361 		printf(
362 "$PIR: Preferring valid BIOS IRQ %d from %d.%d.INT%c for link %#x to IRQ %d\n",
363 		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
364 		    pci_link->pl_id, pci_link->pl_irq);
365 		pci_link->pl_irq = irq;
366 		pci_link->pl_routed = 1;
367 	} else
368 		printf(
369 	"$PIR: BIOS IRQ %d for %d.%d.INT%c does not match link %#x irq %d\n",
370 		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
371 		    pci_link->pl_id, pci_link->pl_irq);
372 }
373 
374 /*
375  * Parse $PIR to enumerate link devices and attempt to determine their
376  * initial state.  This could perhaps be cleaner if we had drivers for the
377  * various interrupt routers as they could read the initial IRQ for each
378  * link.
379  */
380 static void
381 pci_pir_parse(void)
382 {
383 	char tunable_buffer[64];
384 	struct pci_link *pci_link;
385 	int i, irq;
386 
387 	/* Only parse once. */
388 	if (pir_parsed)
389 		return;
390 	pir_parsed = 1;
391 
392 	/* Enumerate link devices. */
393 	TAILQ_INIT(&pci_links);
394 	pci_pir_walk_table(pci_pir_create_links, NULL);
395 	if (bootverbose) {
396 		printf("$PIR: Links after initial probe:\n");
397 		pci_pir_dump_links();
398 	}
399 
400 	/*
401 	 * Check to see if the BIOS has already routed any of the links by
402 	 * checking each device connected to each link to see if it has a
403 	 * valid IRQ.
404 	 */
405 	pci_pir_walk_table(pci_pir_initial_irqs, NULL);
406 	if (bootverbose) {
407 		printf("$PIR: Links after initial IRQ discovery:\n");
408 		pci_pir_dump_links();
409 	}
410 
411 	/*
412 	 * Allow the user to override the IRQ for a given link device.  We
413 	 * allow invalid IRQs to be specified but warn about them.  An IRQ
414 	 * of 255 or 0 clears any preset IRQ.
415 	 */
416 	i = 0;
417 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
418 		snprintf(tunable_buffer, sizeof(tunable_buffer),
419 		    "hw.pci.link.%#x.irq", pci_link->pl_id);
420 		if (getenv_int(tunable_buffer, &irq) == 0)
421 			continue;
422 		if (irq == 0)
423 			irq = PCI_INVALID_IRQ;
424 		if (irq != PCI_INVALID_IRQ &&
425 		    !pci_pir_valid_irq(pci_link, irq) && bootverbose)
426 			printf(
427 		"$PIR: Warning, IRQ %d for link %#x is not listed as valid\n",
428 			    irq, pci_link->pl_id);
429 		pci_link->pl_routed = 0;
430 		pci_link->pl_irq = irq;
431 		i = 1;
432 	}
433 	if (bootverbose && i) {
434 		printf("$PIR: Links after tunable overrides:\n");
435 		pci_pir_dump_links();
436 	}
437 
438 	/*
439 	 * Build initial interrupt weights as well as bitmap of "known-good"
440 	 * IRQs that the BIOS has already used for PCI link devices.
441 	 */
442 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
443 		if (!PCI_INTERRUPT_VALID(pci_link->pl_irq))
444 			continue;
445 		pir_bios_irqs |= 1 << pci_link->pl_irq;
446 		pir_interrupt_weight[pci_link->pl_irq] +=
447 		    pci_link->pl_references;
448 	}
449 	if (bootverbose) {
450 		printf("$PIR: IRQs used by BIOS: ");
451 		pci_print_irqmask(pir_bios_irqs);
452 		printf("\n");
453 		printf("$PIR: Interrupt Weights:\n[ ");
454 		for (i = 0; i < NUM_ISA_INTERRUPTS; i++)
455 			printf(" %3d", i);
456 		printf(" ]\n[ ");
457 		for (i = 0; i < NUM_ISA_INTERRUPTS; i++)
458 			printf(" %3d", pir_interrupt_weight[i]);
459 		printf(" ]\n");
460 	}
461 }
462 
463 /*
464  * Use the PCI BIOS to route an interrupt for a given device.
465  *
466  * Input:
467  * AX = PCIBIOS_ROUTE_INTERRUPT
468  * BH = bus
469  * BL = device [7:3] / function [2:0]
470  * CH = IRQ
471  * CL = Interrupt Pin (0x0A = A, ... 0x0D = D)
472  */
473 static int
474 pci_pir_biosroute(int bus, int device, int func, int pin, int irq)
475 {
476 	struct bios_regs args;
477 
478 	args.eax = PCIBIOS_ROUTE_INTERRUPT;
479 	args.ebx = (bus << 8) | (device << 3) | func;
480 	args.ecx = (irq << 8) | (0xa + pin);
481 	return (bios32(&args, PCIbios.ventry, GSEL(GCODE_SEL, SEL_KPL)));
482 }
483 
484 
485 /*
486  * Route a PCI interrupt using a link device from the $PIR.
487  */
488 int
489 pci_pir_route_interrupt(int bus, int device, int func, int pin)
490 {
491 	struct pci_link_lookup lookup;
492 	struct pci_link *pci_link;
493 	int error, irq;
494 
495 	if (pci_route_table == NULL)
496 		return (PCI_INVALID_IRQ);
497 
498 	/* Lookup link device for this PCI device/pin. */
499 	pci_link = NULL;
500 	lookup.bus = bus;
501 	lookup.device = device;
502 	lookup.pin = pin - 1;
503 	lookup.pci_link_ptr = &pci_link;
504 	pci_pir_walk_table(pci_pir_find_link_handler, &lookup);
505 	if (pci_link == NULL) {
506 		printf("$PIR: No matching entry for %d.%d.INT%c\n", bus,
507 		    device, pin - 1 + 'A');
508 		return (PCI_INVALID_IRQ);
509 	}
510 
511 	/*
512 	 * Pick a new interrupt if we don't have one already.  We look
513 	 * for an interrupt from several different sets.  First, if
514 	 * this link only has one valid IRQ, use that.  Second, we
515 	 * check the set of PCI only interrupts from the $PIR.  Third,
516 	 * we check the set of known-good interrupts that the BIOS has
517 	 * already used.  Lastly, we check the "all possible valid
518 	 * IRQs" set.
519 	 */
520 	if (!PCI_INTERRUPT_VALID(pci_link->pl_irq)) {
521 		if (pci_link->pl_irqmask != 0 && powerof2(pci_link->pl_irqmask))
522 			irq = ffs(pci_link->pl_irqmask) - 1;
523 		else
524 			irq = pci_pir_choose_irq(pci_link,
525 			    pci_route_table->pt_header.ph_pci_irqs);
526 		if (!PCI_INTERRUPT_VALID(irq))
527 			irq = pci_pir_choose_irq(pci_link, pir_bios_irqs);
528 		if (!PCI_INTERRUPT_VALID(irq))
529 			irq = pci_pir_choose_irq(pci_link,
530 			    pci_irq_override_mask);
531 		if (!PCI_INTERRUPT_VALID(irq)) {
532 			if (bootverbose)
533 				printf(
534 			"$PIR: Failed to route interrupt for %d:%d INT%c\n",
535 				    bus, device, pin - 1 + 'A');
536 			return (PCI_INVALID_IRQ);
537 		}
538 		pci_link->pl_irq = irq;
539 	}
540 
541 	/* Ask the BIOS to route this IRQ if we haven't done so already. */
542 	if (!pci_link->pl_routed) {
543 		error = pci_pir_biosroute(bus, device, func, pin - 1,
544 		    pci_link->pl_irq);
545 
546 		/* Ignore errors when routing a unique interrupt. */
547 		if (error && !powerof2(pci_link->pl_irqmask)) {
548 			printf("$PIR: ROUTE_INTERRUPT failed.\n");
549 			return (PCI_INVALID_IRQ);
550 		}
551 		pci_link->pl_routed = 1;
552 
553 		/* Ensure the interrupt is set to level/low trigger. */
554 		KASSERT(pir_device != NULL, ("missing pir device"));
555 		BUS_CONFIG_INTR(pir_device, pci_link->pl_irq,
556 		    INTR_TRIGGER_LEVEL, INTR_POLARITY_LOW);
557 	}
558 	if (bootverbose)
559 		printf("$PIR: %d:%d INT%c routed to irq %d\n", bus, device,
560 		    pin - 1 + 'A', pci_link->pl_irq);
561 	return (pci_link->pl_irq);
562 }
563 
564 /*
565  * Try to pick an interrupt for the specified link from the interrupts
566  * set in the mask.
567  */
568 static int
569 pci_pir_choose_irq(struct pci_link *pci_link, int irqmask)
570 {
571 	int i, irq, realmask;
572 
573 	/* XXX: Need to have a #define of known bad IRQs to also mask out? */
574 	realmask = pci_link->pl_irqmask & irqmask;
575 	if (realmask == 0)
576 		return (PCI_INVALID_IRQ);
577 
578 	/* Find IRQ with lowest weight. */
579 	irq = PCI_INVALID_IRQ;
580 	for (i = 0; i < NUM_ISA_INTERRUPTS; i++) {
581 		if (!(realmask & 1 << i))
582 			continue;
583 		if (irq == PCI_INVALID_IRQ ||
584 		    pir_interrupt_weight[i] < pir_interrupt_weight[irq])
585 			irq = i;
586 	}
587 	if (bootverbose && PCI_INTERRUPT_VALID(irq)) {
588 		printf("$PIR: Found IRQ %d for link %#x from ", irq,
589 		    pci_link->pl_id);
590 		pci_print_irqmask(realmask);
591 		printf("\n");
592 	}
593 	return (irq);
594 }
595 
596 static void
597 pci_print_irqmask(u_int16_t irqs)
598 {
599 	int i, first;
600 
601 	if (irqs == 0) {
602 		printf("none");
603 		return;
604 	}
605 	first = 1;
606 	for (i = 0; i < 16; i++, irqs >>= 1)
607 		if (irqs & 1) {
608 			if (!first)
609 				printf(" ");
610 			else
611 				first = 0;
612 			printf("%d", i);
613 		}
614 }
615 
616 /*
617  * Display link devices.
618  */
619 static void
620 pci_pir_dump_links(void)
621 {
622 	struct pci_link *pci_link;
623 
624 	printf("Link  IRQ  Rtd  Ref  IRQs\n");
625 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
626 		printf("%#4x  %3d   %c   %3d  ", pci_link->pl_id,
627 		    pci_link->pl_irq, pci_link->pl_routed ? 'Y' : 'N',
628 		    pci_link->pl_references);
629 		pci_print_irqmask(pci_link->pl_irqmask);
630 		printf("\n");
631 	}
632 }
633 
634 /*
635  * See if any interrupts for a given PCI bus are routed in the PIR.  Don't
636  * even bother looking if the BIOS doesn't support routing anyways.  If we
637  * are probing a PCI-PCI bridge, then require_parse will be true and we should
638  * only succeed if a host-PCI bridge has already attached and parsed the PIR.
639  */
640 int
641 pci_pir_probe(int bus, int require_parse)
642 {
643 	int i;
644 
645 	if (pci_route_table == NULL || (require_parse && !pir_parsed))
646 		return (0);
647 	for (i = 0; i < pci_route_count; i++)
648 		if (pci_route_table->pt_entry[i].pe_bus == bus)
649 			return (1);
650 	return (0);
651 }
652 
653 /*
654  * The driver for the new-bus psuedo device pir0 for the $PIR table.
655  */
656 
657 static int
658 pir_probe(device_t dev)
659 {
660 	char buf[64];
661 
662 	snprintf(buf, sizeof(buf), "PCI Interrupt Routing Table: %d Entries",
663 	    pci_route_count);
664 	device_set_desc_copy(dev, buf);
665 	return (0);
666 }
667 
668 static int
669 pir_attach(device_t dev)
670 {
671 
672 	pci_pir_parse();
673 	KASSERT(pir_device == NULL, ("Multiple pir devices"));
674 	pir_device = dev;
675 	return (0);
676 }
677 
678 static void
679 pir_resume_find_device(struct PIR_entry *entry, struct PIR_intpin *intpin,
680     void *arg)
681 {
682 	struct pci_dev_lookup *pd;
683 
684 	pd = (struct pci_dev_lookup *)arg;
685 	if (intpin->link != pd->link || pd->bus != -1)
686 		return;
687 	pd->bus = entry->pe_bus;
688 	pd->device = entry->pe_device;
689 	pd->pin = intpin - entry->pe_intpin;
690 }
691 
692 static int
693 pir_resume(device_t dev)
694 {
695 	struct pci_dev_lookup pd;
696 	struct pci_link *pci_link;
697 	int error;
698 
699 	/* Ask the BIOS to re-route each link that was already routed. */
700 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
701 		if (!PCI_INTERRUPT_VALID(pci_link->pl_irq)) {
702 			KASSERT(!pci_link->pl_routed,
703 			    ("link %#x is routed but has invalid PCI IRQ",
704 			    pci_link->pl_id));
705 			continue;
706 		}
707 		if (pci_link->pl_routed) {
708 			pd.bus = -1;
709 			pd.link = pci_link->pl_id;
710 			pci_pir_walk_table(pir_resume_find_device, &pd);
711 			KASSERT(pd.bus != -1,
712 		("did not find matching entry for link %#x in the $PIR table",
713 			    pci_link->pl_id));
714 			if (bootverbose)
715 				device_printf(dev,
716 			    "Using %d.%d.INT%c to route link %#x to IRQ %d\n",
717 				    pd.bus, pd.device, pd.pin + 'A',
718 				    pci_link->pl_id, pci_link->pl_irq);
719 			error = pci_pir_biosroute(pd.bus, pd.device, 0, pd.pin,
720 			    pci_link->pl_irq);
721 			if (error)
722 				device_printf(dev,
723 			    "ROUTE_INTERRUPT on resume for link %#x failed.\n",
724 				    pci_link->pl_id);
725 		}
726 	}
727 	return (0);
728 }
729 
730 static device_method_t pir_methods[] = {
731 	/* Device interface */
732 	DEVMETHOD(device_probe,		pir_probe),
733 	DEVMETHOD(device_attach,	pir_attach),
734 	DEVMETHOD(device_resume,	pir_resume),
735 
736 	{ 0, 0 }
737 };
738 
739 static driver_t pir_driver = {
740 	"pir",
741 	pir_methods,
742 	1,
743 };
744 
745 static devclass_t pir_devclass;
746 
747 DRIVER_MODULE(pir, legacy, pir_driver, pir_devclass, 0, 0);
748