xref: /freebsd/sys/i386/pci/pci_pir.c (revision 7937bfbc0ca53fe7cdd0d54414f9296e273a518e)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 1997, Stefan Esser <se@freebsd.org>
5  * Copyright (c) 2000, Michael Smith <msmith@freebsd.org>
6  * Copyright (c) 2000, BSDi
7  * All rights reserved.
8  * Copyright (c) 2004, John Baldwin <jhb@FreeBSD.org>
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice unmodified, this list of conditions, and the following
15  *    disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/bus.h>
35 #include <sys/kernel.h>
36 #include <sys/malloc.h>
37 #include <sys/module.h>
38 #include <sys/sysctl.h>
39 #include <vm/vm.h>
40 #include <vm/pmap.h>
41 #include <vm/vm_param.h>
42 #include <machine/md_var.h>
43 #include <dev/pci/pcivar.h>
44 #include <dev/pci/pcireg.h>
45 #include <machine/pci_cfgreg.h>
46 #include <machine/segments.h>
47 #include <machine/pc/bios.h>
48 
49 #define	NUM_ISA_INTERRUPTS	16
50 
51 /*
52  * A link device.  Loosely based on the ACPI PCI link device.  This doesn't
53  * try to support priorities for different ISA interrupts.
54  */
55 struct pci_link {
56 	TAILQ_ENTRY(pci_link) pl_links;
57 	uint8_t		pl_id;
58 	uint8_t		pl_irq;
59 	uint16_t	pl_irqmask;
60 	int		pl_references;
61 	int		pl_routed;
62 };
63 
64 struct pci_link_lookup {
65 	struct pci_link	**pci_link_ptr;
66 	int		bus;
67 	int		device;
68 	int		pin;
69 };
70 
71 struct pci_dev_lookup {
72 	uint8_t		link;
73 	int		bus;
74 	int		device;
75 	int		pin;
76 };
77 
78 typedef void pir_entry_handler(struct PIR_entry *entry,
79     struct PIR_intpin* intpin, void *arg);
80 
81 static void	pci_print_irqmask(u_int16_t irqs);
82 static int	pci_pir_biosroute(int bus, int device, int func, int pin,
83 		    int irq);
84 static int	pci_pir_choose_irq(struct pci_link *pci_link, int irqmask);
85 static void	pci_pir_create_links(struct PIR_entry *entry,
86 		    struct PIR_intpin *intpin, void *arg);
87 static void	pci_pir_dump_links(void);
88 static struct pci_link *pci_pir_find_link(uint8_t link_id);
89 static void	pci_pir_find_link_handler(struct PIR_entry *entry,
90 		    struct PIR_intpin *intpin, void *arg);
91 static void	pci_pir_initial_irqs(struct PIR_entry *entry,
92 		    struct PIR_intpin *intpin, void *arg);
93 static void	pci_pir_parse(void);
94 static uint8_t	pci_pir_search_irq(int bus, int device, int pin);
95 static int	pci_pir_valid_irq(struct pci_link *pci_link, int irq);
96 static void	pci_pir_walk_table(pir_entry_handler *handler, void *arg);
97 
98 static MALLOC_DEFINE(M_PIR, "$PIR", "$PIR structures");
99 
100 static struct PIR_table *pci_route_table;
101 static device_t pir_device;
102 static int pci_route_count, pir_bios_irqs, pir_parsed;
103 static TAILQ_HEAD(, pci_link) pci_links;
104 static int pir_interrupt_weight[NUM_ISA_INTERRUPTS];
105 
106 /* sysctl vars */
107 SYSCTL_DECL(_hw_pci);
108 
109 /* XXX this likely should live in a header file */
110 /* IRQs 3, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15 */
111 #define PCI_IRQ_OVERRIDE_MASK 0xdef8
112 
113 static uint32_t pci_irq_override_mask = PCI_IRQ_OVERRIDE_MASK;
114 SYSCTL_INT(_hw_pci, OID_AUTO, irq_override_mask, CTLFLAG_RDTUN,
115     &pci_irq_override_mask, PCI_IRQ_OVERRIDE_MASK,
116     "Mask of allowed irqs to try to route when it has no good clue about\n"
117     "which irqs it should use.");
118 
119 /*
120  * Look for the interrupt routing table.
121  *
122  * We use PCI BIOS's PIR table if it's available. $PIR is the standard way
123  * to do this.  Sadly, some machines are not standards conforming and have
124  * _PIR instead.  We shrug and cope by looking for both.
125  */
126 void
127 pci_pir_open(void)
128 {
129 	struct PIR_table *pt;
130 	uint32_t sigaddr;
131 	int i;
132 	uint8_t ck, *cv;
133 
134 	/* Don't try if we've already found a table. */
135 	if (pci_route_table != NULL)
136 		return;
137 
138 	/* Look for $PIR and then _PIR. */
139 	sigaddr = bios_sigsearch(0, "$PIR", 4, 16, 0);
140 	if (sigaddr == 0)
141 		sigaddr = bios_sigsearch(0, "_PIR", 4, 16, 0);
142 	if (sigaddr == 0)
143 		return;
144 
145 	/* If we found something, check the checksum and length. */
146 	/* XXX - Use pmap_mapdev()? */
147 	pt = (struct PIR_table *)(uintptr_t)BIOS_PADDRTOVADDR(sigaddr);
148 	if (pt->pt_header.ph_length <= sizeof(struct PIR_header))
149 		return;
150 	for (cv = (u_int8_t *)pt, ck = 0, i = 0;
151 	     i < (pt->pt_header.ph_length); i++)
152 		ck += cv[i];
153 	if (ck != 0)
154 		return;
155 
156 	/* Ok, we've got a valid table. */
157 	pci_route_table = pt;
158 	pci_route_count = (pt->pt_header.ph_length -
159 	    sizeof(struct PIR_header)) /
160 	    sizeof(struct PIR_entry);
161 }
162 
163 /*
164  * Find the pci_link structure for a given link ID.
165  */
166 static struct pci_link *
167 pci_pir_find_link(uint8_t link_id)
168 {
169 	struct pci_link *pci_link;
170 
171 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
172 		if (pci_link->pl_id == link_id)
173 			return (pci_link);
174 	}
175 	return (NULL);
176 }
177 
178 /*
179  * Find the link device associated with a PCI device in the table.
180  */
181 static void
182 pci_pir_find_link_handler(struct PIR_entry *entry, struct PIR_intpin *intpin,
183     void *arg)
184 {
185 	struct pci_link_lookup *lookup;
186 
187 	lookup = (struct pci_link_lookup *)arg;
188 	if (entry->pe_bus == lookup->bus &&
189 	    entry->pe_device == lookup->device &&
190 	    intpin - entry->pe_intpin == lookup->pin)
191 		*lookup->pci_link_ptr = pci_pir_find_link(intpin->link);
192 }
193 
194 /*
195  * Check to see if a possible IRQ setting is valid.
196  */
197 static int
198 pci_pir_valid_irq(struct pci_link *pci_link, int irq)
199 {
200 
201 	if (!PCI_INTERRUPT_VALID(irq))
202 		return (0);
203 	return (pci_link->pl_irqmask & (1 << irq));
204 }
205 
206 /*
207  * Walk the $PIR executing the worker function for each valid intpin entry
208  * in the table.  The handler is passed a pointer to both the entry and
209  * the intpin in the entry.
210  */
211 static void
212 pci_pir_walk_table(pir_entry_handler *handler, void *arg)
213 {
214 	struct PIR_entry *entry;
215 	struct PIR_intpin *intpin;
216 	int i, pin;
217 
218 	entry = &pci_route_table->pt_entry[0];
219 	for (i = 0; i < pci_route_count; i++, entry++) {
220 		intpin = &entry->pe_intpin[0];
221 		for (pin = 0; pin < 4; pin++, intpin++)
222 			if (intpin->link != 0)
223 				handler(entry, intpin, arg);
224 	}
225 }
226 
227 static void
228 pci_pir_create_links(struct PIR_entry *entry, struct PIR_intpin *intpin,
229     void *arg)
230 {
231 	struct pci_link *pci_link;
232 
233 	pci_link = pci_pir_find_link(intpin->link);
234 	if (pci_link != NULL) {
235 		pci_link->pl_references++;
236 		if (intpin->irqs != pci_link->pl_irqmask) {
237 			if (bootverbose)
238 				printf(
239 	"$PIR: Entry %d.%d.INT%c has different mask for link %#x, merging\n",
240 				    entry->pe_bus, entry->pe_device,
241 				    (intpin - entry->pe_intpin) + 'A',
242 				    pci_link->pl_id);
243 			pci_link->pl_irqmask &= intpin->irqs;
244 		}
245 	} else {
246 		pci_link = malloc(sizeof(struct pci_link), M_PIR, M_WAITOK);
247 		pci_link->pl_id = intpin->link;
248 		pci_link->pl_irqmask = intpin->irqs;
249 		pci_link->pl_irq = PCI_INVALID_IRQ;
250 		pci_link->pl_references = 1;
251 		pci_link->pl_routed = 0;
252 		TAILQ_INSERT_TAIL(&pci_links, pci_link, pl_links);
253 	}
254 }
255 
256 /*
257  * Look to see if any of the functions on the PCI device at bus/device
258  * have an interrupt routed to intpin 'pin' by the BIOS.
259  */
260 static uint8_t
261 pci_pir_search_irq(int bus, int device, int pin)
262 {
263 	uint32_t value;
264 	uint8_t func, maxfunc;
265 
266 	/* See if we have a valid device at function 0. */
267 	value = pci_cfgregread(0, bus, device, 0, PCIR_VENDOR, 2);
268 	if (value == PCIV_INVALID)
269 		return (PCI_INVALID_IRQ);
270 	value = pci_cfgregread(0, bus, device, 0, PCIR_HDRTYPE, 1);
271 	if ((value & PCIM_HDRTYPE) > PCI_MAXHDRTYPE)
272 		return (PCI_INVALID_IRQ);
273 	if (value & PCIM_MFDEV)
274 		maxfunc = PCI_FUNCMAX;
275 	else
276 		maxfunc = 0;
277 
278 	/* Scan all possible functions at this device. */
279 	for (func = 0; func <= maxfunc; func++) {
280 		value = pci_cfgregread(0, bus, device, func, PCIR_VENDOR, 2);
281 		if (value == PCIV_INVALID)
282 			continue;
283 		value = pci_cfgregread(0, bus, device, func, PCIR_INTPIN, 1);
284 
285 		/*
286 		 * See if it uses the pin in question.  Note that the passed
287 		 * in pin uses 0 for A, .. 3 for D whereas the intpin
288 		 * register uses 0 for no interrupt, 1 for A, .. 4 for D.
289 		 */
290 		if (value != pin + 1)
291 			continue;
292 		value = pci_cfgregread(0, bus, device, func, PCIR_INTLINE, 1);
293 		if (bootverbose)
294 			printf(
295 		"$PIR: Found matching pin for %d.%d.INT%c at func %d: %d\n",
296 			    bus, device, pin + 'A', func, value);
297 		if (value != PCI_INVALID_IRQ)
298 			return (value);
299 	}
300 	return (PCI_INVALID_IRQ);
301 }
302 
303 /*
304  * Try to initialize IRQ based on this device's IRQ.
305  */
306 static void
307 pci_pir_initial_irqs(struct PIR_entry *entry, struct PIR_intpin *intpin,
308     void *arg)
309 {
310 	struct pci_link *pci_link;
311 	uint8_t irq, pin;
312 
313 	pin = intpin - entry->pe_intpin;
314 	pci_link = pci_pir_find_link(intpin->link);
315 	irq = pci_pir_search_irq(entry->pe_bus, entry->pe_device, pin);
316 	if (irq == PCI_INVALID_IRQ || irq == pci_link->pl_irq)
317 		return;
318 
319 	/* Don't trust any BIOS IRQs greater than 15. */
320 	if (irq >= NUM_ISA_INTERRUPTS) {
321 		printf(
322 	"$PIR: Ignoring invalid BIOS IRQ %d from %d.%d.INT%c for link %#x\n",
323 		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
324 		    pci_link->pl_id);
325 		return;
326 	}
327 
328 	/*
329 	 * If we don't have an IRQ for this link yet, then we trust the
330 	 * BIOS, even if it seems invalid from the $PIR entries.
331 	 */
332 	if (pci_link->pl_irq == PCI_INVALID_IRQ) {
333 		if (!pci_pir_valid_irq(pci_link, irq))
334 			printf(
335 	"$PIR: Using invalid BIOS IRQ %d from %d.%d.INT%c for link %#x\n",
336 			    irq, entry->pe_bus, entry->pe_device, pin + 'A',
337 			    pci_link->pl_id);
338 		pci_link->pl_irq = irq;
339 		pci_link->pl_routed = 1;
340 		return;
341 	}
342 
343 	/*
344 	 * We have an IRQ and it doesn't match the current IRQ for this
345 	 * link.  If the new IRQ is invalid, then warn about it and ignore
346 	 * it.  If the old IRQ is invalid and the new IRQ is valid, then
347 	 * prefer the new IRQ instead.  If both IRQs are valid, then just
348 	 * use the first one.  Note that if we ever get into this situation
349 	 * we are having to guess which setting the BIOS actually routed.
350 	 * Perhaps we should just give up instead.
351 	 */
352 	if (!pci_pir_valid_irq(pci_link, irq)) {
353 		printf(
354 		"$PIR: BIOS IRQ %d for %d.%d.INT%c is not valid for link %#x\n",
355 		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
356 		    pci_link->pl_id);
357 	} else if (!pci_pir_valid_irq(pci_link, pci_link->pl_irq)) {
358 		printf(
359 "$PIR: Preferring valid BIOS IRQ %d from %d.%d.INT%c for link %#x to IRQ %d\n",
360 		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
361 		    pci_link->pl_id, pci_link->pl_irq);
362 		pci_link->pl_irq = irq;
363 		pci_link->pl_routed = 1;
364 	} else
365 		printf(
366 	"$PIR: BIOS IRQ %d for %d.%d.INT%c does not match link %#x irq %d\n",
367 		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
368 		    pci_link->pl_id, pci_link->pl_irq);
369 }
370 
371 /*
372  * Parse $PIR to enumerate link devices and attempt to determine their
373  * initial state.  This could perhaps be cleaner if we had drivers for the
374  * various interrupt routers as they could read the initial IRQ for each
375  * link.
376  */
377 static void
378 pci_pir_parse(void)
379 {
380 	char tunable_buffer[64];
381 	struct pci_link *pci_link;
382 	int i, irq;
383 
384 	/* Only parse once. */
385 	if (pir_parsed)
386 		return;
387 	pir_parsed = 1;
388 
389 	/* Enumerate link devices. */
390 	TAILQ_INIT(&pci_links);
391 	pci_pir_walk_table(pci_pir_create_links, NULL);
392 	if (bootverbose) {
393 		printf("$PIR: Links after initial probe:\n");
394 		pci_pir_dump_links();
395 	}
396 
397 	/*
398 	 * Check to see if the BIOS has already routed any of the links by
399 	 * checking each device connected to each link to see if it has a
400 	 * valid IRQ.
401 	 */
402 	pci_pir_walk_table(pci_pir_initial_irqs, NULL);
403 	if (bootverbose) {
404 		printf("$PIR: Links after initial IRQ discovery:\n");
405 		pci_pir_dump_links();
406 	}
407 
408 	/*
409 	 * Allow the user to override the IRQ for a given link device.  We
410 	 * allow invalid IRQs to be specified but warn about them.  An IRQ
411 	 * of 255 or 0 clears any preset IRQ.
412 	 */
413 	i = 0;
414 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
415 		snprintf(tunable_buffer, sizeof(tunable_buffer),
416 		    "hw.pci.link.%#x.irq", pci_link->pl_id);
417 		if (getenv_int(tunable_buffer, &irq) == 0)
418 			continue;
419 		if (irq == 0)
420 			irq = PCI_INVALID_IRQ;
421 		if (irq != PCI_INVALID_IRQ &&
422 		    !pci_pir_valid_irq(pci_link, irq) && bootverbose)
423 			printf(
424 		"$PIR: Warning, IRQ %d for link %#x is not listed as valid\n",
425 			    irq, pci_link->pl_id);
426 		pci_link->pl_routed = 0;
427 		pci_link->pl_irq = irq;
428 		i = 1;
429 	}
430 	if (bootverbose && i) {
431 		printf("$PIR: Links after tunable overrides:\n");
432 		pci_pir_dump_links();
433 	}
434 
435 	/*
436 	 * Build initial interrupt weights as well as bitmap of "known-good"
437 	 * IRQs that the BIOS has already used for PCI link devices.
438 	 */
439 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
440 		if (!PCI_INTERRUPT_VALID(pci_link->pl_irq))
441 			continue;
442 		pir_bios_irqs |= 1 << pci_link->pl_irq;
443 		pir_interrupt_weight[pci_link->pl_irq] +=
444 		    pci_link->pl_references;
445 	}
446 	if (bootverbose) {
447 		printf("$PIR: IRQs used by BIOS: ");
448 		pci_print_irqmask(pir_bios_irqs);
449 		printf("\n");
450 		printf("$PIR: Interrupt Weights:\n[ ");
451 		for (i = 0; i < NUM_ISA_INTERRUPTS; i++)
452 			printf(" %3d", i);
453 		printf(" ]\n[ ");
454 		for (i = 0; i < NUM_ISA_INTERRUPTS; i++)
455 			printf(" %3d", pir_interrupt_weight[i]);
456 		printf(" ]\n");
457 	}
458 }
459 
460 /*
461  * Use the PCI BIOS to route an interrupt for a given device.
462  *
463  * Input:
464  * AX = PCIBIOS_ROUTE_INTERRUPT
465  * BH = bus
466  * BL = device [7:3] / function [2:0]
467  * CH = IRQ
468  * CL = Interrupt Pin (0x0A = A, ... 0x0D = D)
469  */
470 static int
471 pci_pir_biosroute(int bus, int device, int func, int pin, int irq)
472 {
473 	struct bios_regs args;
474 
475 	args.eax = PCIBIOS_ROUTE_INTERRUPT;
476 	args.ebx = (bus << 8) | (device << 3) | func;
477 	args.ecx = (irq << 8) | (0xa + pin);
478 	return (bios32(&args, PCIbios.ventry, GSEL(GCODE_SEL, SEL_KPL)));
479 }
480 
481 /*
482  * Route a PCI interrupt using a link device from the $PIR.
483  */
484 int
485 pci_pir_route_interrupt(int bus, int device, int func, int pin)
486 {
487 	struct pci_link_lookup lookup;
488 	struct pci_link *pci_link;
489 	int error, irq;
490 
491 	if (pci_route_table == NULL)
492 		return (PCI_INVALID_IRQ);
493 
494 	/* Lookup link device for this PCI device/pin. */
495 	pci_link = NULL;
496 	lookup.bus = bus;
497 	lookup.device = device;
498 	lookup.pin = pin - 1;
499 	lookup.pci_link_ptr = &pci_link;
500 	pci_pir_walk_table(pci_pir_find_link_handler, &lookup);
501 	if (pci_link == NULL) {
502 		printf("$PIR: No matching entry for %d.%d.INT%c\n", bus,
503 		    device, pin - 1 + 'A');
504 		return (PCI_INVALID_IRQ);
505 	}
506 
507 	/*
508 	 * Pick a new interrupt if we don't have one already.  We look
509 	 * for an interrupt from several different sets.  First, if
510 	 * this link only has one valid IRQ, use that.  Second, we
511 	 * check the set of PCI only interrupts from the $PIR.  Third,
512 	 * we check the set of known-good interrupts that the BIOS has
513 	 * already used.  Lastly, we check the "all possible valid
514 	 * IRQs" set.
515 	 */
516 	if (!PCI_INTERRUPT_VALID(pci_link->pl_irq)) {
517 		if (pci_link->pl_irqmask != 0 && powerof2(pci_link->pl_irqmask))
518 			irq = ffs(pci_link->pl_irqmask) - 1;
519 		else
520 			irq = pci_pir_choose_irq(pci_link,
521 			    pci_route_table->pt_header.ph_pci_irqs);
522 		if (!PCI_INTERRUPT_VALID(irq))
523 			irq = pci_pir_choose_irq(pci_link, pir_bios_irqs);
524 		if (!PCI_INTERRUPT_VALID(irq))
525 			irq = pci_pir_choose_irq(pci_link,
526 			    pci_irq_override_mask);
527 		if (!PCI_INTERRUPT_VALID(irq)) {
528 			if (bootverbose)
529 				printf(
530 			"$PIR: Failed to route interrupt for %d:%d INT%c\n",
531 				    bus, device, pin - 1 + 'A');
532 			return (PCI_INVALID_IRQ);
533 		}
534 		pci_link->pl_irq = irq;
535 	}
536 
537 	/* Ask the BIOS to route this IRQ if we haven't done so already. */
538 	if (!pci_link->pl_routed) {
539 		error = pci_pir_biosroute(bus, device, func, pin - 1,
540 		    pci_link->pl_irq);
541 
542 		/* Ignore errors when routing a unique interrupt. */
543 		if (error && !powerof2(pci_link->pl_irqmask)) {
544 			printf("$PIR: ROUTE_INTERRUPT failed.\n");
545 			return (PCI_INVALID_IRQ);
546 		}
547 		pci_link->pl_routed = 1;
548 
549 		/* Ensure the interrupt is set to level/low trigger. */
550 		KASSERT(pir_device != NULL, ("missing pir device"));
551 		BUS_CONFIG_INTR(pir_device, pci_link->pl_irq,
552 		    INTR_TRIGGER_LEVEL, INTR_POLARITY_LOW);
553 	}
554 	if (bootverbose)
555 		printf("$PIR: %d:%d INT%c routed to irq %d\n", bus, device,
556 		    pin - 1 + 'A', pci_link->pl_irq);
557 	return (pci_link->pl_irq);
558 }
559 
560 /*
561  * Try to pick an interrupt for the specified link from the interrupts
562  * set in the mask.
563  */
564 static int
565 pci_pir_choose_irq(struct pci_link *pci_link, int irqmask)
566 {
567 	int i, irq, realmask;
568 
569 	/* XXX: Need to have a #define of known bad IRQs to also mask out? */
570 	realmask = pci_link->pl_irqmask & irqmask;
571 	if (realmask == 0)
572 		return (PCI_INVALID_IRQ);
573 
574 	/* Find IRQ with lowest weight. */
575 	irq = PCI_INVALID_IRQ;
576 	for (i = 0; i < NUM_ISA_INTERRUPTS; i++) {
577 		if (!(realmask & 1 << i))
578 			continue;
579 		if (irq == PCI_INVALID_IRQ ||
580 		    pir_interrupt_weight[i] < pir_interrupt_weight[irq])
581 			irq = i;
582 	}
583 	if (bootverbose && PCI_INTERRUPT_VALID(irq)) {
584 		printf("$PIR: Found IRQ %d for link %#x from ", irq,
585 		    pci_link->pl_id);
586 		pci_print_irqmask(realmask);
587 		printf("\n");
588 	}
589 	return (irq);
590 }
591 
592 static void
593 pci_print_irqmask(u_int16_t irqs)
594 {
595 	int i, first;
596 
597 	if (irqs == 0) {
598 		printf("none");
599 		return;
600 	}
601 	first = 1;
602 	for (i = 0; i < 16; i++, irqs >>= 1)
603 		if (irqs & 1) {
604 			if (!first)
605 				printf(" ");
606 			else
607 				first = 0;
608 			printf("%d", i);
609 		}
610 }
611 
612 /*
613  * Display link devices.
614  */
615 static void
616 pci_pir_dump_links(void)
617 {
618 	struct pci_link *pci_link;
619 
620 	printf("Link  IRQ  Rtd  Ref  IRQs\n");
621 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
622 		printf("%#4x  %3d   %c   %3d  ", pci_link->pl_id,
623 		    pci_link->pl_irq, pci_link->pl_routed ? 'Y' : 'N',
624 		    pci_link->pl_references);
625 		pci_print_irqmask(pci_link->pl_irqmask);
626 		printf("\n");
627 	}
628 }
629 
630 /*
631  * See if any interrupts for a given PCI bus are routed in the PIR.  Don't
632  * even bother looking if the BIOS doesn't support routing anyways.  If we
633  * are probing a PCI-PCI bridge, then require_parse will be true and we should
634  * only succeed if a host-PCI bridge has already attached and parsed the PIR.
635  */
636 int
637 pci_pir_probe(int bus, int require_parse)
638 {
639 	int i;
640 
641 	if (pci_route_table == NULL || (require_parse && !pir_parsed))
642 		return (0);
643 	for (i = 0; i < pci_route_count; i++)
644 		if (pci_route_table->pt_entry[i].pe_bus == bus)
645 			return (1);
646 	return (0);
647 }
648 
649 /*
650  * The driver for the new-bus pseudo device pir0 for the $PIR table.
651  */
652 
653 static int
654 pir_probe(device_t dev)
655 {
656 	device_set_descf(dev, "PCI Interrupt Routing Table: %d Entries",
657 	    pci_route_count);
658 	return (0);
659 }
660 
661 static int
662 pir_attach(device_t dev)
663 {
664 
665 	pci_pir_parse();
666 	KASSERT(pir_device == NULL, ("Multiple pir devices"));
667 	pir_device = dev;
668 	return (0);
669 }
670 
671 static void
672 pir_resume_find_device(struct PIR_entry *entry, struct PIR_intpin *intpin,
673     void *arg)
674 {
675 	struct pci_dev_lookup *pd;
676 
677 	pd = (struct pci_dev_lookup *)arg;
678 	if (intpin->link != pd->link || pd->bus != -1)
679 		return;
680 	pd->bus = entry->pe_bus;
681 	pd->device = entry->pe_device;
682 	pd->pin = intpin - entry->pe_intpin;
683 }
684 
685 static int
686 pir_resume(device_t dev)
687 {
688 	struct pci_dev_lookup pd;
689 	struct pci_link *pci_link;
690 	int error;
691 
692 	/* Ask the BIOS to re-route each link that was already routed. */
693 	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
694 		if (!PCI_INTERRUPT_VALID(pci_link->pl_irq)) {
695 			KASSERT(!pci_link->pl_routed,
696 			    ("link %#x is routed but has invalid PCI IRQ",
697 			    pci_link->pl_id));
698 			continue;
699 		}
700 		if (pci_link->pl_routed) {
701 			pd.bus = -1;
702 			pd.link = pci_link->pl_id;
703 			pci_pir_walk_table(pir_resume_find_device, &pd);
704 			KASSERT(pd.bus != -1,
705 		("did not find matching entry for link %#x in the $PIR table",
706 			    pci_link->pl_id));
707 			if (bootverbose)
708 				device_printf(dev,
709 			    "Using %d.%d.INT%c to route link %#x to IRQ %d\n",
710 				    pd.bus, pd.device, pd.pin + 'A',
711 				    pci_link->pl_id, pci_link->pl_irq);
712 			error = pci_pir_biosroute(pd.bus, pd.device, 0, pd.pin,
713 			    pci_link->pl_irq);
714 			if (error)
715 				device_printf(dev,
716 			    "ROUTE_INTERRUPT on resume for link %#x failed.\n",
717 				    pci_link->pl_id);
718 		}
719 	}
720 	return (0);
721 }
722 
723 static device_method_t pir_methods[] = {
724 	/* Device interface */
725 	DEVMETHOD(device_probe,		pir_probe),
726 	DEVMETHOD(device_attach,	pir_attach),
727 	DEVMETHOD(device_resume,	pir_resume),
728 	{ 0, 0 }
729 };
730 
731 static driver_t pir_driver = {
732 	"pir",
733 	pir_methods,
734 	1,
735 };
736 
737 DRIVER_MODULE(pir, legacy, pir_driver, 0, 0);
738