pci_pir.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1997, Stefan Esser <[email protected]>
 * Copyright (c) 2000, Michael Smith <[email protected]>
 * Copyright (c) 2000, BSDi
 * All rights reserved.
 * Copyright (c) 2004, John Baldwin <[email protected]>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_param.h>
#include <machine/md_var.h>
#include <dev/pci/pcivar.h>
#include <dev/pci/pcireg.h>
#include <machine/pci_cfgreg.h>
#include <machine/segments.h>
#include <machine/pc/bios.h>

#define	NUM_ISA_INTERRUPTS	16

/*
 * A link device.  Loosely based on the ACPI PCI link device.  This doesn't
 * try to support priorities for different ISA interrupts.
 */
struct pci_link {
	TAILQ_ENTRY(pci_link) pl_links;
	uint8_t		pl_id;
	uint8_t		pl_irq;
	uint16_t	pl_irqmask;
	int		pl_references;
	int		pl_routed;
};

struct pci_link_lookup {
	struct pci_link	**pci_link_ptr;
	int		bus;
	int		device;
	int		pin;
};

struct pci_dev_lookup {
	uint8_t		link;
	int		bus;
	int		device;
	int		pin;
};

typedef void pir_entry_handler(struct PIR_entry *entry,
    struct PIR_intpin* intpin, void *arg);

static void	pci_print_irqmask(u_int16_t irqs);
static int	pci_pir_biosroute(int bus, int device, int func, int pin,
		    int irq);
static int	pci_pir_choose_irq(struct pci_link *pci_link, int irqmask);
static void	pci_pir_create_links(struct PIR_entry *entry,
		    struct PIR_intpin *intpin, void *arg);
static void	pci_pir_dump_links(void);
static struct pci_link *pci_pir_find_link(uint8_t link_id);
static void	pci_pir_find_link_handler(struct PIR_entry *entry,
		    struct PIR_intpin *intpin, void *arg);
static void	pci_pir_initial_irqs(struct PIR_entry *entry,
		    struct PIR_intpin *intpin, void *arg);
static void	pci_pir_parse(void);
static uint8_t	pci_pir_search_irq(int bus, int device, int pin);
static int	pci_pir_valid_irq(struct pci_link *pci_link, int irq);
static void	pci_pir_walk_table(pir_entry_handler *handler, void *arg);

static MALLOC_DEFINE(M_PIR, "$PIR", "$PIR structures");

static struct PIR_table *pci_route_table;
static device_t pir_device;
static int pci_route_count, pir_bios_irqs, pir_parsed;
static TAILQ_HEAD(, pci_link) pci_links;
static int pir_interrupt_weight[NUM_ISA_INTERRUPTS];

/* sysctl vars */
SYSCTL_DECL(_hw_pci);

/* XXX this likely should live in a header file */
/* IRQs 3, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15 */
#define PCI_IRQ_OVERRIDE_MASK 0xdef8

static uint32_t pci_irq_override_mask = PCI_IRQ_OVERRIDE_MASK;
SYSCTL_INT(_hw_pci, OID_AUTO, irq_override_mask, CTLFLAG_RDTUN,
    &pci_irq_override_mask, PCI_IRQ_OVERRIDE_MASK,
    "Mask of allowed irqs to try to route when it has no good clue about\n"
    "which irqs it should use.");

/*
 * Look for the interrupt routing table.
 *
 * We use PCI BIOS's PIR table if it's available. $PIR is the standard way
 * to do this.  Sadly, some machines are not standards conforming and have
 * _PIR instead.  We shrug and cope by looking for both.
 */
void
pci_pir_open(void)
{
	struct PIR_table *pt;
	uint32_t sigaddr;
	int i;
	uint8_t ck, *cv;

	/* Don't try if we've already found a table. */
	if (pci_route_table != NULL)
		return;

	/* Look for $PIR and then _PIR. */
	sigaddr = bios_sigsearch(0, "$PIR", 4, 16, 0);
	if (sigaddr == 0)
		sigaddr = bios_sigsearch(0, "_PIR", 4, 16, 0);
	if (sigaddr == 0)
		return;

	/* If we found something, check the checksum and length. */
	/* XXX - Use pmap_mapdev()? */
	pt = (struct PIR_table *)(uintptr_t)BIOS_PADDRTOVADDR(sigaddr);
	if (pt->pt_header.ph_length <= sizeof(struct PIR_header))
		return;
	for (cv = (u_int8_t *)pt, ck = 0, i = 0;
	     i < (pt->pt_header.ph_length); i++)
		ck += cv[i];
	if (ck != 0)
		return;

	/* Ok, we've got a valid table. */
	pci_route_table = pt;
	pci_route_count = (pt->pt_header.ph_length -
	    sizeof(struct PIR_header)) / 
	    sizeof(struct PIR_entry);
}

/*
 * Find the pci_link structure for a given link ID.
 */
static struct pci_link *
pci_pir_find_link(uint8_t link_id)
{
	struct pci_link *pci_link;

	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
		if (pci_link->pl_id == link_id)
			return (pci_link);
	}
	return (NULL);
}

/*
 * Find the link device associated with a PCI device in the table.
 */
static void
pci_pir_find_link_handler(struct PIR_entry *entry, struct PIR_intpin *intpin,
    void *arg)
{
	struct pci_link_lookup *lookup;

	lookup = (struct pci_link_lookup *)arg;
	if (entry->pe_bus == lookup->bus &&
	    entry->pe_device == lookup->device &&
	    intpin - entry->pe_intpin == lookup->pin)
		*lookup->pci_link_ptr = pci_pir_find_link(intpin->link);
}

/*
 * Check to see if a possible IRQ setting is valid.
 */
static int
pci_pir_valid_irq(struct pci_link *pci_link, int irq)
{

	if (!PCI_INTERRUPT_VALID(irq))
		return (0);
	return (pci_link->pl_irqmask & (1 << irq));
}

/*
 * Walk the $PIR executing the worker function for each valid intpin entry
 * in the table.  The handler is passed a pointer to both the entry and
 * the intpin in the entry.
 */
static void
pci_pir_walk_table(pir_entry_handler *handler, void *arg)
{
	struct PIR_entry *entry;
	struct PIR_intpin *intpin;
	int i, pin;

	entry = &pci_route_table->pt_entry[0];
	for (i = 0; i < pci_route_count; i++, entry++) {
		intpin = &entry->pe_intpin[0];
		for (pin = 0; pin < 4; pin++, intpin++)
			if (intpin->link != 0)
				handler(entry, intpin, arg);
	}
}

static void
pci_pir_create_links(struct PIR_entry *entry, struct PIR_intpin *intpin,
    void *arg)
{
	struct pci_link *pci_link;

	pci_link = pci_pir_find_link(intpin->link);
	if (pci_link != NULL) {
		pci_link->pl_references++;
		if (intpin->irqs != pci_link->pl_irqmask) {
			if (bootverbose)
				printf(
	"$PIR: Entry %d.%d.INT%c has different mask for link %#x, merging\n",
				    entry->pe_bus, entry->pe_device,
				    (intpin - entry->pe_intpin) + 'A',
				    pci_link->pl_id);
			pci_link->pl_irqmask &= intpin->irqs;
		}
	} else {
		pci_link = malloc(sizeof(struct pci_link), M_PIR, M_WAITOK);
		pci_link->pl_id = intpin->link;
		pci_link->pl_irqmask = intpin->irqs;
		pci_link->pl_irq = PCI_INVALID_IRQ;
		pci_link->pl_references = 1;
		pci_link->pl_routed = 0;
		TAILQ_INSERT_TAIL(&pci_links, pci_link, pl_links);
	}
}

/*
 * Look to see if any of the functions on the PCI device at bus/device
 * have an interrupt routed to intpin 'pin' by the BIOS.
 */
static uint8_t
pci_pir_search_irq(int bus, int device, int pin)
{
	uint32_t value;
	uint8_t func, maxfunc;

	/* See if we have a valid device at function 0. */
	value = pci_cfgregread(0, bus, device, 0, PCIR_VENDOR, 2);
	if (value == PCIV_INVALID)
		return (PCI_INVALID_IRQ);
	value = pci_cfgregread(0, bus, device, 0, PCIR_HDRTYPE, 1);
	if ((value & PCIM_HDRTYPE) > PCI_MAXHDRTYPE)
		return (PCI_INVALID_IRQ);
	if (value & PCIM_MFDEV)
		maxfunc = PCI_FUNCMAX;
	else
		maxfunc = 0;

	/* Scan all possible functions at this device. */
	for (func = 0; func <= maxfunc; func++) {
		value = pci_cfgregread(0, bus, device, func, PCIR_VENDOR, 2);
		if (value == PCIV_INVALID)
			continue;
		value = pci_cfgregread(0, bus, device, func, PCIR_INTPIN, 1);

		/*
		 * See if it uses the pin in question.  Note that the passed
		 * in pin uses 0 for A, .. 3 for D whereas the intpin
		 * register uses 0 for no interrupt, 1 for A, .. 4 for D.
		 */
		if (value != pin + 1)
			continue;
		value = pci_cfgregread(0, bus, device, func, PCIR_INTLINE, 1);
		if (bootverbose)
			printf(
		"$PIR: Found matching pin for %d.%d.INT%c at func %d: %d\n",
			    bus, device, pin + 'A', func, value);
		if (value != PCI_INVALID_IRQ)
			return (value);
	}
	return (PCI_INVALID_IRQ);
}

/*
 * Try to initialize IRQ based on this device's IRQ.
 */
static void
pci_pir_initial_irqs(struct PIR_entry *entry, struct PIR_intpin *intpin,
    void *arg)
{
	struct pci_link *pci_link;
	uint8_t irq, pin;

	pin = intpin - entry->pe_intpin;
	pci_link = pci_pir_find_link(intpin->link);
	irq = pci_pir_search_irq(entry->pe_bus, entry->pe_device, pin);
	if (irq == PCI_INVALID_IRQ || irq == pci_link->pl_irq)
		return;

	/* Don't trust any BIOS IRQs greater than 15. */
	if (irq >= NUM_ISA_INTERRUPTS) {
		printf(
	"$PIR: Ignoring invalid BIOS IRQ %d from %d.%d.INT%c for link %#x\n",
		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
		    pci_link->pl_id);
		return;
	}

	/*
	 * If we don't have an IRQ for this link yet, then we trust the
	 * BIOS, even if it seems invalid from the $PIR entries.
	 */
	if (pci_link->pl_irq == PCI_INVALID_IRQ) {
		if (!pci_pir_valid_irq(pci_link, irq))
			printf(
	"$PIR: Using invalid BIOS IRQ %d from %d.%d.INT%c for link %#x\n",
			    irq, entry->pe_bus, entry->pe_device, pin + 'A',
			    pci_link->pl_id);
		pci_link->pl_irq = irq;
		pci_link->pl_routed = 1;
		return;
	}

	/*
	 * We have an IRQ and it doesn't match the current IRQ for this
	 * link.  If the new IRQ is invalid, then warn about it and ignore
	 * it.  If the old IRQ is invalid and the new IRQ is valid, then
	 * prefer the new IRQ instead.  If both IRQs are valid, then just
	 * use the first one.  Note that if we ever get into this situation
	 * we are having to guess which setting the BIOS actually routed.
	 * Perhaps we should just give up instead.
	 */
	if (!pci_pir_valid_irq(pci_link, irq)) {
		printf(
		"$PIR: BIOS IRQ %d for %d.%d.INT%c is not valid for link %#x\n",
		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
		    pci_link->pl_id);
	} else if (!pci_pir_valid_irq(pci_link, pci_link->pl_irq)) {
		printf(
"$PIR: Preferring valid BIOS IRQ %d from %d.%d.INT%c for link %#x to IRQ %d\n", 
		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
		    pci_link->pl_id, pci_link->pl_irq);
		pci_link->pl_irq = irq;
		pci_link->pl_routed = 1;
	} else
		printf(
	"$PIR: BIOS IRQ %d for %d.%d.INT%c does not match link %#x irq %d\n",
		    irq, entry->pe_bus, entry->pe_device, pin + 'A',
		    pci_link->pl_id, pci_link->pl_irq);
}

/*
 * Parse $PIR to enumerate link devices and attempt to determine their
 * initial state.  This could perhaps be cleaner if we had drivers for the
 * various interrupt routers as they could read the initial IRQ for each
 * link.
 */
static void
pci_pir_parse(void)
{
	char tunable_buffer[64];
	struct pci_link *pci_link;
	int i, irq;

	/* Only parse once. */
	if (pir_parsed)
		return;
	pir_parsed = 1;

	/* Enumerate link devices. */
	TAILQ_INIT(&pci_links);
	pci_pir_walk_table(pci_pir_create_links, NULL);
	if (bootverbose) {
		printf("$PIR: Links after initial probe:\n");
		pci_pir_dump_links();
	}

	/*
	 * Check to see if the BIOS has already routed any of the links by
	 * checking each device connected to each link to see if it has a
	 * valid IRQ.
	 */
	pci_pir_walk_table(pci_pir_initial_irqs, NULL);
	if (bootverbose) {
		printf("$PIR: Links after initial IRQ discovery:\n");
		pci_pir_dump_links();
	}

	/*
	 * Allow the user to override the IRQ for a given link device.  We
	 * allow invalid IRQs to be specified but warn about them.  An IRQ
	 * of 255 or 0 clears any preset IRQ.
	 */
	i = 0;
	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
		snprintf(tunable_buffer, sizeof(tunable_buffer),
		    "hw.pci.link.%#x.irq", pci_link->pl_id);
		if (getenv_int(tunable_buffer, &irq) == 0)
			continue;
		if (irq == 0)
			irq = PCI_INVALID_IRQ;
		if (irq != PCI_INVALID_IRQ &&
		    !pci_pir_valid_irq(pci_link, irq) && bootverbose)
			printf(
		"$PIR: Warning, IRQ %d for link %#x is not listed as valid\n",
			    irq, pci_link->pl_id);
		pci_link->pl_routed = 0;
		pci_link->pl_irq = irq;
		i = 1;
	}
	if (bootverbose && i) {
		printf("$PIR: Links after tunable overrides:\n");
		pci_pir_dump_links();
	}

	/*
	 * Build initial interrupt weights as well as bitmap of "known-good"
	 * IRQs that the BIOS has already used for PCI link devices.
	 */
	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
		if (!PCI_INTERRUPT_VALID(pci_link->pl_irq))
			continue;
		pir_bios_irqs |= 1 << pci_link->pl_irq;
		pir_interrupt_weight[pci_link->pl_irq] +=
		    pci_link->pl_references;
	}
	if (bootverbose) {
		printf("$PIR: IRQs used by BIOS: ");
		pci_print_irqmask(pir_bios_irqs);
		printf("\n");
		printf("$PIR: Interrupt Weights:\n[ ");
		for (i = 0; i < NUM_ISA_INTERRUPTS; i++)
			printf(" %3d", i);
		printf(" ]\n[ ");
		for (i = 0; i < NUM_ISA_INTERRUPTS; i++)
			printf(" %3d", pir_interrupt_weight[i]);
		printf(" ]\n");
	}
}

/*
 * Use the PCI BIOS to route an interrupt for a given device.
 *
 * Input:
 * AX = PCIBIOS_ROUTE_INTERRUPT
 * BH = bus
 * BL = device [7:3] / function [2:0]
 * CH = IRQ
 * CL = Interrupt Pin (0x0A = A, ... 0x0D = D)
 */
static int
pci_pir_biosroute(int bus, int device, int func, int pin, int irq)
{
	struct bios_regs args;

	args.eax = PCIBIOS_ROUTE_INTERRUPT;
	args.ebx = (bus << 8) | (device << 3) | func;
	args.ecx = (irq << 8) | (0xa + pin);
	return (bios32(&args, PCIbios.ventry, GSEL(GCODE_SEL, SEL_KPL)));
}

/*
 * Route a PCI interrupt using a link device from the $PIR.
 */
int
pci_pir_route_interrupt(int bus, int device, int func, int pin)
{
	struct pci_link_lookup lookup;
	struct pci_link *pci_link;
	int error, irq;

	if (pci_route_table == NULL)
		return (PCI_INVALID_IRQ);

	/* Lookup link device for this PCI device/pin. */
	pci_link = NULL;
	lookup.bus = bus;
	lookup.device = device;
	lookup.pin = pin - 1;
	lookup.pci_link_ptr = &pci_link;
	pci_pir_walk_table(pci_pir_find_link_handler, &lookup);
	if (pci_link == NULL) {
		printf("$PIR: No matching entry for %d.%d.INT%c\n", bus,
		    device, pin - 1 + 'A');
		return (PCI_INVALID_IRQ);
	}

	/*
	 * Pick a new interrupt if we don't have one already.  We look
	 * for an interrupt from several different sets.  First, if
	 * this link only has one valid IRQ, use that.  Second, we
	 * check the set of PCI only interrupts from the $PIR.  Third,
	 * we check the set of known-good interrupts that the BIOS has
	 * already used.  Lastly, we check the "all possible valid
	 * IRQs" set.
	 */
	if (!PCI_INTERRUPT_VALID(pci_link->pl_irq)) {
		if (pci_link->pl_irqmask != 0 && powerof2(pci_link->pl_irqmask))
			irq = ffs(pci_link->pl_irqmask) - 1;
		else
			irq = pci_pir_choose_irq(pci_link,
			    pci_route_table->pt_header.ph_pci_irqs);
		if (!PCI_INTERRUPT_VALID(irq))
			irq = pci_pir_choose_irq(pci_link, pir_bios_irqs);
		if (!PCI_INTERRUPT_VALID(irq))
			irq = pci_pir_choose_irq(pci_link,
			    pci_irq_override_mask);
		if (!PCI_INTERRUPT_VALID(irq)) {
			if (bootverbose)
				printf(
			"$PIR: Failed to route interrupt for %d:%d INT%c\n",
				    bus, device, pin - 1 + 'A');
			return (PCI_INVALID_IRQ);
		}
		pci_link->pl_irq = irq;
	}

	/* Ask the BIOS to route this IRQ if we haven't done so already. */
	if (!pci_link->pl_routed) {
		error = pci_pir_biosroute(bus, device, func, pin - 1,
		    pci_link->pl_irq);

		/* Ignore errors when routing a unique interrupt. */
		if (error && !powerof2(pci_link->pl_irqmask)) {
			printf("$PIR: ROUTE_INTERRUPT failed.\n");
			return (PCI_INVALID_IRQ);
		}
		pci_link->pl_routed = 1;

		/* Ensure the interrupt is set to level/low trigger. */
		KASSERT(pir_device != NULL, ("missing pir device"));
		BUS_CONFIG_INTR(pir_device, pci_link->pl_irq,
		    INTR_TRIGGER_LEVEL, INTR_POLARITY_LOW);
	}
	if (bootverbose)
		printf("$PIR: %d:%d INT%c routed to irq %d\n", bus, device,
		    pin - 1 + 'A', pci_link->pl_irq);
	return (pci_link->pl_irq);
}

/*
 * Try to pick an interrupt for the specified link from the interrupts
 * set in the mask.
 */
static int
pci_pir_choose_irq(struct pci_link *pci_link, int irqmask)
{
	int i, irq, realmask;

	/* XXX: Need to have a #define of known bad IRQs to also mask out? */
	realmask = pci_link->pl_irqmask & irqmask;
	if (realmask == 0)
		return (PCI_INVALID_IRQ);

	/* Find IRQ with lowest weight. */
	irq = PCI_INVALID_IRQ;
	for (i = 0; i < NUM_ISA_INTERRUPTS; i++) {
		if (!(realmask & 1 << i))
			continue;
		if (irq == PCI_INVALID_IRQ ||
		    pir_interrupt_weight[i] < pir_interrupt_weight[irq])
			irq = i;
	}
	if (bootverbose && PCI_INTERRUPT_VALID(irq)) {
		printf("$PIR: Found IRQ %d for link %#x from ", irq,
		    pci_link->pl_id);
		pci_print_irqmask(realmask);
		printf("\n");
	}
	return (irq);
}

static void
pci_print_irqmask(u_int16_t irqs)
{
	int i, first;

	if (irqs == 0) {
		printf("none");
		return;
	}
	first = 1;
	for (i = 0; i < 16; i++, irqs >>= 1)
		if (irqs & 1) {
			if (!first)
				printf(" ");
			else
				first = 0;
			printf("%d", i);
		}
}

/*
 * Display link devices.
 */
static void
pci_pir_dump_links(void)
{
	struct pci_link *pci_link;

	printf("Link  IRQ  Rtd  Ref  IRQs\n");
	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
		printf("%#4x  %3d   %c   %3d  ", pci_link->pl_id,
		    pci_link->pl_irq, pci_link->pl_routed ? 'Y' : 'N',
		    pci_link->pl_references);
		pci_print_irqmask(pci_link->pl_irqmask);
		printf("\n");
	}
}

/*
 * See if any interrupts for a given PCI bus are routed in the PIR.  Don't
 * even bother looking if the BIOS doesn't support routing anyways.  If we
 * are probing a PCI-PCI bridge, then require_parse will be true and we should
 * only succeed if a host-PCI bridge has already attached and parsed the PIR.
 */
int
pci_pir_probe(int bus, int require_parse)
{
	int i;

	if (pci_route_table == NULL || (require_parse && !pir_parsed))
		return (0);
	for (i = 0; i < pci_route_count; i++)
		if (pci_route_table->pt_entry[i].pe_bus == bus)
			return (1);
	return (0);
}

/*
 * The driver for the new-bus pseudo device pir0 for the $PIR table.
 */

static int
pir_probe(device_t dev)
{
	device_set_descf(dev, "PCI Interrupt Routing Table: %d Entries",
	    pci_route_count);
	return (0);
}

static int
pir_attach(device_t dev)
{

	pci_pir_parse();
	KASSERT(pir_device == NULL, ("Multiple pir devices"));
	pir_device = dev;
	return (0);
}

static void
pir_resume_find_device(struct PIR_entry *entry, struct PIR_intpin *intpin,
    void *arg)
{
	struct pci_dev_lookup *pd;

	pd = (struct pci_dev_lookup *)arg;
	if (intpin->link != pd->link || pd->bus != -1)
		return;
	pd->bus = entry->pe_bus;
	pd->device = entry->pe_device;
	pd->pin = intpin - entry->pe_intpin;
}

static int
pir_resume(device_t dev)
{
	struct pci_dev_lookup pd;
	struct pci_link *pci_link;
	int error;

	/* Ask the BIOS to re-route each link that was already routed. */
	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
		if (!PCI_INTERRUPT_VALID(pci_link->pl_irq)) {
			KASSERT(!pci_link->pl_routed,
			    ("link %#x is routed but has invalid PCI IRQ",
			    pci_link->pl_id));
			continue;
		}
		if (pci_link->pl_routed) {
			pd.bus = -1;
			pd.link = pci_link->pl_id;
			pci_pir_walk_table(pir_resume_find_device, &pd);
			KASSERT(pd.bus != -1,
		("did not find matching entry for link %#x in the $PIR table",
			    pci_link->pl_id));
			if (bootverbose)
				device_printf(dev,
			    "Using %d.%d.INT%c to route link %#x to IRQ %d\n",
				    pd.bus, pd.device, pd.pin + 'A',
				    pci_link->pl_id, pci_link->pl_irq);
			error = pci_pir_biosroute(pd.bus, pd.device, 0, pd.pin,
			    pci_link->pl_irq);
			if (error)
				device_printf(dev,
			    "ROUTE_INTERRUPT on resume for link %#x failed.\n",
				    pci_link->pl_id);
		}
	}
	return (0);
}

static device_method_t pir_methods[] = {
	/* Device interface */
	DEVMETHOD(device_probe,		pir_probe),
	DEVMETHOD(device_attach,	pir_attach),
	DEVMETHOD(device_resume,	pir_resume),
	{ 0, 0 }
};

static driver_t pir_driver = {
	"pir",
	pir_methods,
	1,
};

DRIVER_MODULE(pir, legacy, pir_driver, 0, 0);