/*      $NetBSD: acpi_pci_link.c,v 1.30 2026/04/07 22:22:11 andvar Exp $        */

/*-
 * Copyright (c) 2002 Mitsuru IWASAKI <iwasaki@jp.freebsd.org>
 * All rights reserved.
 *
 * 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, 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: acpi_pci_link.c,v 1.30 2026/04/07 22:22:11 andvar Exp $");

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/reboot.h>
#include <sys/systm.h>

#include <dev/acpi/acpireg.h>
#include <dev/acpi/acpivar.h>

#include <dev/pci/pcireg.h>

#include "opt_acpi.h"


#define _COMPONENT          ACPI_BUS_COMPONENT
ACPI_MODULE_NAME            ("acpi_pci_link")

MALLOC_DECLARE(M_ACPI);

#define NUM_ISA_INTERRUPTS      16
#define NUM_ACPI_INTERRUPTS     256

#define PCI_INVALID_IRQ 255
#define PCI_INTERRUPT_VALID(x) ((x) != PCI_INVALID_IRQ && (x) != 0)

#define ACPI_SERIAL_BEGIN(x)
#define ACPI_SERIAL_END(x)

/*
 * An ACPI PCI link device may contain multiple links.  Each link has its
 * own ACPI resource.  _PRT entries specify which link is being used via
 * the Source Index.
 *
 * XXX: A note about Source Indices and DPFs:  Currently we assume that
 * the DPF start and end tags are not counted towards the index that
 * Source Index corresponds to.  Also, we assume that when DPFs are in use
 * they various sets overlap in terms of Indices.  Here's an example
 * resource list indicating these assumptions:
 *
 * Resource             Index
 * --------             -----
 * I/O Port             0
 * Start DPF            -
 * IRQ                  1
 * MemIO                2
 * Start DPF            -
 * IRQ                  1
 * MemIO                2
 * End DPF              -
 * DMA Channel          3
 *
 * The XXX is because I'm not sure if this is a valid assumption to make.
 */

/* States during DPF processing. */
#define DPF_OUTSIDE     0
#define DPF_FIRST       1
#define DPF_IGNORE      2

struct link;

struct acpi_pci_link_softc {
        int     pl_num_links;
        int     pl_crs_bad;
        struct link *pl_links;
        char pl_name[32];
        ACPI_HANDLE pl_handle;
        TAILQ_ENTRY(acpi_pci_link_softc) pl_list;
};

static TAILQ_HEAD(, acpi_pci_link_softc) acpi_pci_linkdevs =
    TAILQ_HEAD_INITIALIZER(acpi_pci_linkdevs);


struct link {
        struct acpi_pci_link_softc *l_sc;
        uint8_t l_bios_irq;
        uint8_t l_irq;
        uint8_t l_trig;
        uint8_t l_pol;
        uint8_t l_initial_irq;
        int     l_res_index;
        int     l_num_irqs;
        int     *l_irqs;
        int     l_references;
        int     l_dev_count;
        pcitag_t *l_devices;
        u_int   l_routed:1;
        u_int   l_isa_irq:1;
        ACPI_RESOURCE l_prs_template;
};

struct link_count_request {
        int     in_dpf;
        int     count;
};

struct link_res_request {
        struct acpi_pci_link_softc *sc;
        int     in_dpf;
        int     res_index;
        int     link_index;
};

static int pci_link_interrupt_weights[NUM_ACPI_INTERRUPTS];
static int pci_link_bios_isa_irqs;

static ACPI_STATUS acpi_count_irq_resources(ACPI_RESOURCE *, void *);
static ACPI_STATUS link_add_crs(ACPI_RESOURCE *, void *);
static ACPI_STATUS link_add_prs(ACPI_RESOURCE *, void *);
static int link_valid_irq(struct link *, int);
static void acpi_pci_link_dump(struct acpi_pci_link_softc *);
static int acpi_pci_link_attach(struct acpi_pci_link_softc *);
static uint8_t acpi_pci_link_search_irq(struct acpi_pci_link_softc *,
                                        pci_chipset_tag_t, int, int, int);
static struct link *acpi_pci_link_lookup(struct acpi_pci_link_softc *, int);
static ACPI_STATUS acpi_pci_link_srs(struct acpi_pci_link_softc *,
                                     ACPI_BUFFER *);
static ACPI_STATUS acpi_AppendBufferResource(ACPI_BUFFER *, ACPI_RESOURCE *);

static ACPI_STATUS
acpi_count_irq_resources(ACPI_RESOURCE *res, void *context)
{
        struct link_count_request *req;

        req = (struct link_count_request *)context;
        switch (res->Type) {
        case ACPI_RESOURCE_TYPE_START_DEPENDENT:
                switch (req->in_dpf) {
                case DPF_OUTSIDE:
                        /* We've started the first DPF. */
                        req->in_dpf = DPF_FIRST;
                        break;
                case DPF_FIRST:
                        /* We've started the second DPF. */
                        req->in_dpf = DPF_IGNORE;
                        break;
                }
                break;
        case ACPI_RESOURCE_TYPE_END_DEPENDENT:
                /* We are finished with DPF parsing. */
                KASSERT(req->in_dpf != DPF_OUTSIDE);
                req->in_dpf = DPF_OUTSIDE;
                break;
        case ACPI_RESOURCE_TYPE_IRQ:
        case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
                /*
                 * Don't count resources if we are in a DPF set that we are
                 * ignoring.
                 */
                if (req->in_dpf != DPF_IGNORE)
                        req->count++;
        }
        return AE_OK;
}

static ACPI_STATUS
link_add_crs(ACPI_RESOURCE *res, void *context)
{
        struct link_res_request *req;
        struct link *link;

        req = (struct link_res_request *)context;
        switch (res->Type) {
        case ACPI_RESOURCE_TYPE_START_DEPENDENT:
                switch (req->in_dpf) {
                case DPF_OUTSIDE:
                        /* We've started the first DPF. */
                        req->in_dpf = DPF_FIRST;
                        break;
                case DPF_FIRST:
                        /* We've started the second DPF. */
                        panic(
                "%s: Multiple dependent functions within a current resource",
                            __func__);
                        break;
                }
                break;
        case ACPI_RESOURCE_TYPE_END_DEPENDENT:
                /* We are finished with DPF parsing. */
                KASSERT(req->in_dpf != DPF_OUTSIDE);
                req->in_dpf = DPF_OUTSIDE;
                break;
        case ACPI_RESOURCE_TYPE_IRQ:
        case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
                KASSERT(req->link_index < req->sc->pl_num_links);
                link = &req->sc->pl_links[req->link_index];
                link->l_res_index = req->res_index;
                req->link_index++;
                req->res_index++;

                /*
                 * Only use the current value if there's one IRQ.  Some
                 * systems return multiple IRQs (which is nonsense for _CRS)
                 * when the link hasn't been programmed.
                 */
                if (res->Type == ACPI_RESOURCE_TYPE_IRQ) {
                        if (res->Data.Irq.InterruptCount == 1) {
                                link->l_irq = res->Data.Irq.Interrupts[0];
                                link->l_trig = res->Data.Irq.Triggering;
                                link->l_pol = res->Data.Irq.Polarity;
                        }
                } else if (res->Data.ExtendedIrq.InterruptCount == 1) {
                        link->l_irq = res->Data.ExtendedIrq.Interrupts[0];
                        link->l_trig = res->Data.ExtendedIrq.Triggering;
                        link->l_pol = res->Data.ExtendedIrq.Polarity;
                }

                /*
                 * An IRQ of zero means that the link isn't routed.
                 */
                if (link->l_irq == 0)
                        link->l_irq = PCI_INVALID_IRQ;
                break;
        default:
                req->res_index++;
        }
        return AE_OK;
}

/*
 * Populate the set of possible IRQs for each device.
 */
static ACPI_STATUS
link_add_prs(ACPI_RESOURCE *res, void *context)
{
        ACPI_RESOURCE *tmp;
        struct link_res_request *req;
        struct link *link;
        uint8_t *irqs = NULL;
        uint32_t *ext_irqs = NULL;
        int i, is_ext_irq = 1;

        req = (struct link_res_request *)context;
        switch (res->Type) {
        case ACPI_RESOURCE_TYPE_START_DEPENDENT:
                switch (req->in_dpf) {
                case DPF_OUTSIDE:
                        /* We've started the first DPF. */
                        req->in_dpf = DPF_FIRST;
                        break;
                case DPF_FIRST:
                        /* We've started the second DPF. */
                        req->in_dpf = DPF_IGNORE;
                        break;
                }
                break;
        case ACPI_RESOURCE_TYPE_END_DEPENDENT:
                /* We are finished with DPF parsing. */
                KASSERT(req->in_dpf != DPF_OUTSIDE);
                req->in_dpf = DPF_OUTSIDE;
                break;
        case ACPI_RESOURCE_TYPE_IRQ:
                is_ext_irq = 0;
                /* fall through */
        case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
                /*
                 * Don't parse resources if we are in a DPF set that we are
                 * ignoring.
                 */
                if (req->in_dpf == DPF_IGNORE)
                        break;

                KASSERT(req->link_index < req->sc->pl_num_links);
                link = &req->sc->pl_links[req->link_index];
                if (link->l_res_index == -1) {
                        KASSERT(req->sc->pl_crs_bad);
                        link->l_res_index = req->res_index;
                }
                req->link_index++;
                req->res_index++;

                /*
                 * Stash a copy of the resource for later use when doing
                 * _SRS.
                 */
                tmp = &link->l_prs_template;
                if (is_ext_irq) {
                        memcpy(tmp, res, ACPI_RS_SIZE(tmp->Data.ExtendedIrq));

                        /*
                         * XXX acpi_AppendBufferResource() cannot handle
                         * optional data.
                         */
                        memset(&tmp->Data.ExtendedIrq.ResourceSource, 0,
                            sizeof(tmp->Data.ExtendedIrq.ResourceSource));
                        tmp->Length = ACPI_RS_SIZE(tmp->Data.ExtendedIrq);

                        link->l_num_irqs =
                            res->Data.ExtendedIrq.InterruptCount;
                        link->l_trig = res->Data.ExtendedIrq.Triggering;
                        link->l_pol = res->Data.ExtendedIrq.Polarity;
                        ext_irqs = res->Data.ExtendedIrq.Interrupts;
                } else {
                        memcpy(tmp, res, ACPI_RS_SIZE(tmp->Data.Irq));
                        link->l_num_irqs = res->Data.Irq.InterruptCount;
                        link->l_trig = res->Data.Irq.Triggering;
                        link->l_pol = res->Data.Irq.Polarity;
                        irqs = res->Data.Irq.Interrupts;
                }
                if (link->l_num_irqs == 0)
                        break;

                /*
                 * Save a list of the valid IRQs.  Also, if all of the
                 * valid IRQs are ISA IRQs, then mark this link as
                 * routed via an ISA interrupt.
                 */
                link->l_isa_irq = TRUE;
                link->l_irqs = malloc(sizeof(int) * link->l_num_irqs,
                    M_ACPI, M_WAITOK | M_ZERO);
                for (i = 0; i < link->l_num_irqs; i++) {
                        if (is_ext_irq) {
                                link->l_irqs[i] = ext_irqs[i];
                                if (ext_irqs[i] >= NUM_ISA_INTERRUPTS)
                                        link->l_isa_irq = FALSE;
                        } else {
                                link->l_irqs[i] = irqs[i];
                                if (irqs[i] >= NUM_ISA_INTERRUPTS)
                                        link->l_isa_irq = FALSE;
                        }
                }
                break;
        default:
                if (req->in_dpf == DPF_IGNORE)
                        break;
                if (req->sc->pl_crs_bad)
                        aprint_normal("%s: Warning: possible resource %d "
                               "will be lost during _SRS\n", req->sc->pl_name,
                               req->res_index);
                req->res_index++;
        }
        return AE_OK;
}

static int
link_valid_irq(struct link *link, int irq)
{
        int i;

        /* Invalid interrupts are never valid. */
        if (!PCI_INTERRUPT_VALID(irq))
                return FALSE;

        /* Any interrupt in the list of possible interrupts is valid. */
        for (i = 0; i < link->l_num_irqs; i++)
                if (link->l_irqs[i] == irq)
                         return TRUE;

        /*
         * For links routed via an ISA interrupt, if the SCI is routed via
         * an ISA interrupt, the SCI is always treated as a valid IRQ.
         */
        if (link->l_isa_irq && AcpiGbl_FADT.SciInterrupt == irq &&
            irq < NUM_ISA_INTERRUPTS)
                return TRUE;

        /* If the interrupt wasn't found in the list it is not valid. */
        return FALSE;
}

void
acpi_pci_link_state(void)
{
        struct acpi_pci_link_softc *sc;

        TAILQ_FOREACH(sc, &acpi_pci_linkdevs, pl_list) {
                acpi_pci_link_dump(sc);
        }
}

static void
acpi_pci_link_dump(struct acpi_pci_link_softc *sc)
{
        struct link *link;
        int i, j;

        printf("Link Device %s:\n", sc->pl_name);
        printf("Index  IRQ  Rtd  Ref  IRQs\n");
        for (i = 0; i < sc->pl_num_links; i++) {
                link = &sc->pl_links[i];
                printf("%5d  %3d   %c   %3d ", i, link->l_irq,
                    link->l_routed ? 'Y' : 'N',  link->l_references);
                if (link->l_num_irqs == 0)
                        printf(" none");
                else for (j = 0; j < link->l_num_irqs; j++)
                        printf(" %d", link->l_irqs[j]);
                printf(" polarity %u trigger %u\n", link->l_pol, link->l_trig);
        }
        printf("\n");
}

static int
acpi_pci_link_attach(struct acpi_pci_link_softc *sc)
{
        struct link_count_request creq;
        struct link_res_request rreq;
        ACPI_STATUS status;
        int i;

        ACPI_SERIAL_BEGIN(pci_link);

        /*
         * Count the number of current resources so we know how big of
         * a link array to allocate.  On some systems, _CRS is broken,
         * so for those systems try to derive the count from _PRS instead.
         */
        creq.in_dpf = DPF_OUTSIDE;
        creq.count = 0;
        status = AcpiWalkResources(sc->pl_handle, "_CRS",
            acpi_count_irq_resources, &creq);
        sc->pl_crs_bad = ACPI_FAILURE(status);
        if (sc->pl_crs_bad) {
                creq.in_dpf = DPF_OUTSIDE;
                creq.count = 0;
                status = AcpiWalkResources(sc->pl_handle, "_PRS",
                    acpi_count_irq_resources, &creq);
                if (ACPI_FAILURE(status)) {
                        aprint_error("%s: Unable to parse _CRS or _PRS: %s\n",
                            sc->pl_name, AcpiFormatException(status));
                        ACPI_SERIAL_END(pci_link);
                        return ENXIO;
                }
        }
        sc->pl_num_links = creq.count;
        if (creq.count == 0) {
                ACPI_SERIAL_END(pci_link);
                return 0;
        }
        sc->pl_links = malloc(sizeof(struct link) * sc->pl_num_links,
            M_ACPI, M_WAITOK | M_ZERO);

        /* Initialize the child links. */
        for (i = 0; i < sc->pl_num_links; i++) {
                sc->pl_links[i].l_irq = PCI_INVALID_IRQ;
                sc->pl_links[i].l_bios_irq = PCI_INVALID_IRQ;
                sc->pl_links[i].l_sc = sc;
                sc->pl_links[i].l_isa_irq = FALSE;
                sc->pl_links[i].l_res_index = -1;
                sc->pl_links[i].l_dev_count = 0;
                sc->pl_links[i].l_devices = NULL;
        }

        /* Try to read the current settings from _CRS if it is valid. */
        if (!sc->pl_crs_bad) {
                rreq.in_dpf = DPF_OUTSIDE;
                rreq.link_index = 0;
                rreq.res_index = 0;
                rreq.sc = sc;
                status = AcpiWalkResources(sc->pl_handle, "_CRS",
                    link_add_crs, &rreq);
                if (ACPI_FAILURE(status)) {
                        aprint_error("%s: Unable to parse _CRS: %s\n",
                            sc->pl_name, AcpiFormatException(status));
                        goto fail;
                }
        }

        /*
         * Try to read the possible settings from _PRS.  Note that if the
         * _CRS is toast, we depend on having a working _PRS.  However, if
         * _CRS works, then it is ok for _PRS to be missing.
         */
        rreq.in_dpf = DPF_OUTSIDE;
        rreq.link_index = 0;
        rreq.res_index = 0;
        rreq.sc = sc;
        status = AcpiWalkResources(sc->pl_handle, "_PRS",
            link_add_prs, &rreq);
        if (ACPI_FAILURE(status) &&
            (status != AE_NOT_FOUND || sc->pl_crs_bad)) {
                aprint_error("%s: Unable to parse _PRS: %s\n",
                    sc->pl_name, AcpiFormatException(status));
                goto fail;
        }
        if (boothowto & AB_VERBOSE) {
                aprint_normal("%s: Links after initial probe:\n", sc->pl_name);
                acpi_pci_link_dump(sc);
        }

        /* Verify initial IRQs if we have _PRS. */
        if (status != AE_NOT_FOUND)
                for (i = 0; i < sc->pl_num_links; i++)
                        if (!link_valid_irq(&sc->pl_links[i],
                            sc->pl_links[i].l_irq))
                                sc->pl_links[i].l_irq = PCI_INVALID_IRQ;
        if (boothowto & AB_VERBOSE) {
                printf("%s: Links after initial validation:\n", sc->pl_name);
                acpi_pci_link_dump(sc);
        }

        /* Save initial IRQs. */
        for (i = 0; i < sc->pl_num_links; i++)
                sc->pl_links[i].l_initial_irq = sc->pl_links[i].l_irq;

        /*
         * Try to disable this link.  If successful, set the current IRQ to
         * zero and flags to indicate this link is not routed.  If we can't
         * run _DIS (i.e., the method doesn't exist), assume the initial
         * IRQ was routed by the BIOS.
         */
#ifndef ACPI__DIS_IS_BROKEN
        if (ACPI_SUCCESS(AcpiEvaluateObject(sc->pl_handle, "_DIS", NULL,
            NULL)))
                for (i = 0; i < sc->pl_num_links; i++)
                        sc->pl_links[i].l_irq = PCI_INVALID_IRQ;
        else
#endif
                for (i = 0; i < sc->pl_num_links; i++)
                        if (PCI_INTERRUPT_VALID(sc->pl_links[i].l_irq))
                                sc->pl_links[i].l_routed = TRUE;
        if (boothowto & AB_VERBOSE) {
                printf("%s: Links after disable:\n", sc->pl_name);
                acpi_pci_link_dump(sc);
        }
        ACPI_SERIAL_END(pci_link);
        return 0;
fail:
        ACPI_SERIAL_END(pci_link);
        for (i = 0; i < sc->pl_num_links; i++) {
                if (sc->pl_links[i].l_irqs != NULL)
                        free(sc->pl_links[i].l_irqs, M_ACPI);
                if (sc->pl_links[i].l_devices != NULL)
                        free(sc->pl_links[i].l_devices, M_ACPI);
        }
        free(sc->pl_links, M_ACPI);
        return ENXIO;
}

static void
acpi_pci_link_add_functions(struct acpi_pci_link_softc *sc, struct link *link,
    pci_chipset_tag_t pc, int bus, int device, int pin)
{
        uint32_t value;
        uint8_t func, maxfunc, ipin;
        pcitag_t tag;

        tag = pci_make_tag(pc, bus, device, 0);
        /* See if we have a valid device at function 0. */
        value = pci_conf_read(pc, tag,  PCI_BHLC_REG);
        if (PCI_HDRTYPE_TYPE(value) > PCI_HDRTYPE_PCB)
                return;
        if (PCI_HDRTYPE_MULTIFN(value))
                maxfunc = 7;
        else
                maxfunc = 0;

        /* Scan all possible functions at this device. */
        for (func = 0; func <= maxfunc; func++) {
                tag = pci_make_tag(pc, bus, device, func);
                value = pci_conf_read(pc, tag, PCI_ID_REG);
                if (PCI_VENDOR(value) == 0xffff)
                        continue;
                value = pci_conf_read(pc, tag,
                    PCI_INTERRUPT_REG);
                ipin = PCI_INTERRUPT_PIN(value);
                /*
                 * 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 (ipin != pin + 1)
                        continue;

                link->l_devices = realloc(link->l_devices,
                    sizeof(pcitag_t) * (link->l_dev_count + 1),
                    M_ACPI, M_WAITOK);
                link->l_devices[link->l_dev_count] = tag;
                ++link->l_dev_count;
        }
}

static uint8_t
acpi_pci_link_search_irq(struct acpi_pci_link_softc *sc, pci_chipset_tag_t pc,
    int bus, int device, int pin)
{
        uint32_t value;
        uint8_t func, maxfunc, ipin, iline;
        pcitag_t tag;

        tag = pci_make_tag(pc, bus, device, 0);
        /* See if we have a valid device at function 0. */
        value = pci_conf_read(pc, tag,  PCI_BHLC_REG);
        if (PCI_HDRTYPE_TYPE(value) > PCI_HDRTYPE_PCB)
                return PCI_INVALID_IRQ;
        if (PCI_HDRTYPE_MULTIFN(value))
                maxfunc = 7;
        else
                maxfunc = 0;

        /* Scan all possible functions at this device. */
        for (func = 0; func <= maxfunc; func++) {
                tag = pci_make_tag(pc, bus, device, func);
                value = pci_conf_read(pc, tag, PCI_ID_REG);
                if (PCI_VENDOR(value) == 0xffff)
                        continue;
                value = pci_conf_read(pc, tag,
                    PCI_INTERRUPT_REG);
                ipin = PCI_INTERRUPT_PIN(value);
                iline = PCI_INTERRUPT_LINE(value);

                /*
                 * 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 (ipin != pin + 1)
                        continue;
                aprint_verbose(
                    "%s: ACPI: Found matching pin for %d.%d.INT%c"
                    " at func %d: %d\n",
                            sc->pl_name, bus, device, pin + 'A', func, iline);
                if (PCI_INTERRUPT_VALID(iline))
                        return iline;
        }
        return PCI_INVALID_IRQ;
}

/*
 * Find the link structure that corresponds to the resource index passed in
 * via 'source_index'.
 */
static struct link *
acpi_pci_link_lookup(struct acpi_pci_link_softc *sc, int source_index)
{
        int i;

        for (i = 0; i < sc->pl_num_links; i++)
                if (sc->pl_links[i].l_res_index == source_index)
                        return &sc->pl_links[i];
        return NULL;
}

void
acpi_pci_link_add_reference(void *v, pci_chipset_tag_t pc, int index,
    int bus, int slot, int pin)
{
        struct acpi_pci_link_softc *sc = v;
        struct link *link;
        uint8_t bios_irq;

        /* Bump the reference count. */
        ACPI_SERIAL_BEGIN(pci_link);
        link = acpi_pci_link_lookup(sc, index);
        if (link == NULL) {
                printf("%s: apparently invalid index %d\n", sc->pl_name, index);
                ACPI_SERIAL_END(pci_link);
                return;
        }
        link->l_references++;
        acpi_pci_link_add_functions(sc, link, pc, bus, slot, pin);
        if (link->l_routed)
                pci_link_interrupt_weights[link->l_irq]++;

        /*
         * The BIOS only routes interrupts via ISA IRQs using the ATPICs
         * (8259As).  Thus, if this link is routed via an ISA IRQ, go
         * look to see if the BIOS routed an IRQ for this link at the
         * indicated (bus, slot, pin).  If so, we prefer that IRQ for
         * this link and add that IRQ to our list of known-good IRQs.
         * This provides a good work-around for link devices whose _CRS
         * method is either broken or bogus.  We only use the value
         * returned by _CRS if we can't find a valid IRQ via this method
         * in fact.
         *
         * If this link is not routed via an ISA IRQ (because we are using
         * APIC for example), then don't bother looking up the BIOS IRQ
         * as if we find one it won't be valid anyway.
         */
        if (!link->l_isa_irq) {
                ACPI_SERIAL_END(pci_link);
                return;
        }

        /* Try to find a BIOS IRQ setting from any matching devices. */
        bios_irq = acpi_pci_link_search_irq(sc, pc, bus, slot, pin);
        if (!PCI_INTERRUPT_VALID(bios_irq)) {
                ACPI_SERIAL_END(pci_link);
                return;
        }

        /* Validate the BIOS IRQ. */
        if (!link_valid_irq(link, bios_irq)) {
                printf("%s: BIOS IRQ %u for %d.%d.INT%c is invalid\n",
                    sc->pl_name, bios_irq, (int)bus, slot, pin + 'A');
        } else if (!PCI_INTERRUPT_VALID(link->l_bios_irq)) {
                link->l_bios_irq = bios_irq;
                if (bios_irq < NUM_ISA_INTERRUPTS)
                        pci_link_bios_isa_irqs |= (1 << bios_irq);
                if (bios_irq != link->l_initial_irq &&
                    PCI_INTERRUPT_VALID(link->l_initial_irq))
                        printf(
                            "%s: BIOS IRQ %u does not match initial IRQ %u\n",
                            sc->pl_name, bios_irq, link->l_initial_irq);
        } else if (bios_irq != link->l_bios_irq)
                printf(
            "%s: BIOS IRQ %u for %d.%d.INT%c does not match "
            "previous BIOS IRQ %u\n",
                    sc->pl_name, bios_irq, (int)bus, slot, pin + 'A',
                    link->l_bios_irq);
        ACPI_SERIAL_END(pci_link);
}

static ACPI_STATUS
acpi_pci_link_srs_from_crs(struct acpi_pci_link_softc *sc, ACPI_BUFFER *srsbuf)
{
        ACPI_RESOURCE *end, *res;
        ACPI_STATUS status;
        struct link *link;
        int i, in_dpf;

        /* Fetch the _CRS. */
        srsbuf->Pointer = NULL;
        srsbuf->Length = ACPI_ALLOCATE_BUFFER;
        status = AcpiGetCurrentResources(sc->pl_handle, srsbuf);
        if (ACPI_SUCCESS(status) && srsbuf->Pointer == NULL)
                status = AE_NO_MEMORY;
        if (ACPI_FAILURE(status)) {
                aprint_verbose("%s: Unable to fetch current resources: %s\n",
                    sc->pl_name, AcpiFormatException(status));
                return status;
        }

        /* Fill in IRQ resources via link structures. */
        link = sc->pl_links;
        i = 0;
        in_dpf = DPF_OUTSIDE;
        res = (ACPI_RESOURCE *)srsbuf->Pointer;
        end = (ACPI_RESOURCE *)((char *)srsbuf->Pointer + srsbuf->Length);
        for (;;) {
                switch (res->Type) {
                case ACPI_RESOURCE_TYPE_START_DEPENDENT:
                        switch (in_dpf) {
                        case DPF_OUTSIDE:
                                /* We've started the first DPF. */
                                in_dpf = DPF_FIRST;
                                break;
                        case DPF_FIRST:
                                /* We've started the second DPF. */
                                panic(
                "%s: Multiple dependent functions within a current resource",
                                    __func__);
                                break;
                        }
                        break;
                case ACPI_RESOURCE_TYPE_END_DEPENDENT:
                        /* We are finished with DPF parsing. */
                        KASSERT(in_dpf != DPF_OUTSIDE);
                        in_dpf = DPF_OUTSIDE;
                        break;
                case ACPI_RESOURCE_TYPE_IRQ:
                        res->Data.Irq.InterruptCount = 1;
                        if (PCI_INTERRUPT_VALID(link->l_irq)) {
                                KASSERT(link->l_irq < NUM_ISA_INTERRUPTS);
                                res->Data.Irq.Interrupts[0] = link->l_irq;
                                res->Data.Irq.Triggering = link->l_trig;
                                res->Data.Irq.Polarity = link->l_pol;
                        } else
                                res->Data.Irq.Interrupts[0] = 0;
                        link++;
                        i++;
                        break;
                case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
                        res->Data.ExtendedIrq.InterruptCount = 1;
                        if (PCI_INTERRUPT_VALID(link->l_irq)) {
                                res->Data.ExtendedIrq.Interrupts[0] =
                                    link->l_irq;
                                res->Data.ExtendedIrq.Triggering =
                                    link->l_trig;
                                res->Data.ExtendedIrq.Polarity = link->l_pol;
                        } else
                                res->Data.ExtendedIrq.Interrupts[0] = 0;
                        link++;
                        i++;
                        break;
                }
                if (res->Type == ACPI_RESOURCE_TYPE_END_TAG)
                        break;
                res = ACPI_NEXT_RESOURCE(res);
                if (res >= end)
                        break;
        }
        return AE_OK;
}

static ACPI_STATUS
acpi_pci_link_srs_from_links(struct acpi_pci_link_softc *sc,
    ACPI_BUFFER *srsbuf)
{
        ACPI_RESOURCE newres;
        ACPI_STATUS status;
        struct link *link;
        int i;

        /* Start off with an empty buffer. */
        srsbuf->Pointer = NULL;
        link = sc->pl_links;
        for (i = 0; i < sc->pl_num_links; i++) {

                /* Add a new IRQ resource from each link. */
                link = &sc->pl_links[i];
                if (link->l_prs_template.Type == ACPI_RESOURCE_TYPE_IRQ) {

                        /* Build an IRQ resource. */
                        bcopy(&link->l_prs_template, &newres,
                            ACPI_RS_SIZE(newres.Data.Irq));
                        newres.Data.Irq.InterruptCount = 1;
                        if (PCI_INTERRUPT_VALID(link->l_irq)) {
                                KASSERT(link->l_irq < NUM_ISA_INTERRUPTS);
                                newres.Data.Irq.Interrupts[0] = link->l_irq;
                                newres.Data.Irq.Triggering = link->l_trig;
                                newres.Data.Irq.Polarity = link->l_pol;
                        } else
                                newres.Data.Irq.Interrupts[0] = 0;
                } else {

                        /* Build an ExtIRQ resource. */
                        bcopy(&link->l_prs_template, &newres,
                            ACPI_RS_SIZE(newres.Data.ExtendedIrq));
                        newres.Data.ExtendedIrq.InterruptCount = 1;
                        if (PCI_INTERRUPT_VALID(link->l_irq)) {
                                newres.Data.ExtendedIrq.Interrupts[0] =
                                    link->l_irq;
                                newres.Data.ExtendedIrq.Triggering =
                                    link->l_trig;
                                newres.Data.ExtendedIrq.Polarity =
                                    link->l_pol;
                        } else {
                                newres.Data.ExtendedIrq.Interrupts[0] = 0;
                        }
                }

                /* Add the new resource to the end of the _SRS buffer. */
                status = acpi_AppendBufferResource(srsbuf, &newres);
                if (ACPI_FAILURE(status)) {
                        printf("%s: Unable to build resources: %s\n",
                            sc->pl_name, AcpiFormatException(status));
                        if (srsbuf->Pointer != NULL)
                                ACPI_FREE(srsbuf->Pointer);
                        return status;
                }
        }
        return AE_OK;
}

static ACPI_STATUS
acpi_pci_link_srs(struct acpi_pci_link_softc *sc, ACPI_BUFFER *srsbuf)
{
        ACPI_STATUS status;

        if (sc->pl_crs_bad)
                status = acpi_pci_link_srs_from_links(sc, srsbuf);
        else
                status = acpi_pci_link_srs_from_crs(sc, srsbuf);

        if (ACPI_FAILURE(status))
                printf("%s: Unable to find link srs : %s\n",
                    sc->pl_name, AcpiFormatException(status));

        /* Write out new resources via _SRS. */
        return AcpiSetCurrentResources(sc->pl_handle, srsbuf);
}

static ACPI_STATUS
acpi_pci_link_route_irqs(struct acpi_pci_link_softc *sc, int *irq, int *pol,
                         int *trig)
{
        ACPI_RESOURCE *resource, *end;
        ACPI_BUFFER srsbuf;
        ACPI_STATUS status;
        struct link *link;
        int i, is_ext = 0;

        status = acpi_pci_link_srs(sc, &srsbuf);
        if (ACPI_FAILURE(status)) {
                printf("%s: _SRS failed: %s\n",
                    sc->pl_name, AcpiFormatException(status));
                return status;
        }
        /*
         * Perform acpi_config_intr() on each IRQ resource if it was just
         * routed for the first time.
         */
        link = sc->pl_links;
        i = 0;
        resource = (ACPI_RESOURCE *)srsbuf.Pointer;
        end = (ACPI_RESOURCE *)((char *)srsbuf.Pointer + srsbuf.Length);
        for (;;) {
                if (resource->Type == ACPI_RESOURCE_TYPE_END_TAG)
                        break;
                switch (resource->Type) {
                case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
                        is_ext = 1;
                        /* FALLTHROUGH */
                case ACPI_RESOURCE_TYPE_IRQ:
                        /*
                         * Only configure the interrupt and update the
                         * weights if this link has a valid IRQ and was
                         * previously unrouted.
                         */
                        if (!link->l_routed &&
                            PCI_INTERRUPT_VALID(link->l_irq)) {
                                *trig = is_ext ?
                                    resource->Data.ExtendedIrq.Triggering :
                                    resource->Data.Irq.Triggering;
                                *pol = is_ext ?
                                    resource->Data.ExtendedIrq.Polarity :
                                    resource->Data.Irq.Polarity;
                                *irq = is_ext ?
                                    resource->Data.ExtendedIrq.Interrupts[0] :
                                    resource->Data.Irq.Interrupts[0];
                                link->l_routed = TRUE;
                                pci_link_interrupt_weights[link->l_irq] +=
                                    link->l_references;
                        }
                        link++;
                        i++;
                        break;
                }
                resource = ACPI_NEXT_RESOURCE(resource);
                if (resource >= end)
                        break;
        }
        ACPI_FREE(srsbuf.Pointer);
        return AE_OK;
}

/*
 * Pick an IRQ to use for this unrouted link.
 */
static uint8_t
acpi_pci_link_choose_irq(struct acpi_pci_link_softc *sc, struct link *link)
{
        u_int8_t best_irq, pos_irq;
        int best_weight, pos_weight, i;

        KASSERT(!link->l_routed);
        KASSERT(!PCI_INTERRUPT_VALID(link->l_irq));

        /*
         * If we have a valid BIOS IRQ, use that.  We trust what the BIOS
         * says it routed over what _CRS says the link thinks is routed.
         */
        if (PCI_INTERRUPT_VALID(link->l_bios_irq))
                return link->l_bios_irq;

        /*
         * If we don't have a BIOS IRQ but do have a valid IRQ from _CRS,
         * then use that.
         */
        if (PCI_INTERRUPT_VALID(link->l_initial_irq))
                return link->l_initial_irq;

        /*
         * Ok, we have no useful hints, so we have to pick from the
         * possible IRQs.  For ISA IRQs we only use interrupts that
         * have already been used by the BIOS.
         */
        best_irq = PCI_INVALID_IRQ;
        best_weight = INT_MAX;
        for (i = 0; i < link->l_num_irqs; i++) {
                pos_irq = link->l_irqs[i];
                if (pos_irq < NUM_ISA_INTERRUPTS &&
                    (pci_link_bios_isa_irqs & 1 << pos_irq) == 0)
                        continue;
                pos_weight = pci_link_interrupt_weights[pos_irq];
                if (pos_weight < best_weight) {
                        best_weight = pos_weight;
                        best_irq = pos_irq;
                }
        }

        /*
         * If this is an ISA IRQ, try using the SCI if it is also an ISA
         * interrupt as a fallback.
         */
        if (link->l_isa_irq && !PCI_INTERRUPT_VALID(best_irq)) {
                pos_irq = AcpiGbl_FADT.SciInterrupt;
                pos_weight = pci_link_interrupt_weights[pos_irq];
                if (pos_weight < best_weight) {
                        best_weight = pos_weight;
                        best_irq = pos_irq;
                }
        }

        if (PCI_INTERRUPT_VALID(best_irq)) {
                aprint_verbose("%s: Picked IRQ %u with weight %d\n",
                    sc->pl_name, best_irq, best_weight);
        } else
                printf("%s: Unable to choose an IRQ\n", sc->pl_name);
        return best_irq;
}

int
acpi_pci_link_route_interrupt(void *v, pci_chipset_tag_t pc, int index,
    int *irq, int *pol, int *trig)
{
        struct acpi_pci_link_softc *sc = v;
        struct link *link;
        int i;
        pcireg_t reg;

        ACPI_SERIAL_BEGIN(pci_link);
        link = acpi_pci_link_lookup(sc, index);
        if (link == NULL)
                panic("%s: apparently invalid index %d", __func__, index);

        /*
         * If this link device is already routed to an interrupt, just return
         * the interrupt it is routed to.
         */
        if (link->l_routed) {
                KASSERT(PCI_INTERRUPT_VALID(link->l_irq));
                ACPI_SERIAL_END(pci_link);
                *irq = link->l_irq;
                *pol = link->l_pol;
                *trig = link->l_trig;
                return link->l_irq;
        }

        if (PCI_INTERRUPT_VALID(link->l_irq)) {
                *irq = link->l_irq;
                *pol = link->l_pol;
                *trig = link->l_trig;
                goto done;
        }

        /* The link device doesn't have an interrupt, so try to choose one. */
        link->l_irq = acpi_pci_link_choose_irq(sc, link);
        if (!PCI_INTERRUPT_VALID(link->l_irq))
                goto done;

        /*
         * Try to route the interrupt we picked.  If it fails, then
         * assume the interrupt is not routed.
         */
        acpi_pci_link_route_irqs(sc, irq, pol, trig);
        if (!link->l_routed) {
                link->l_irq = PCI_INVALID_IRQ;
                goto done;
        }

        link->l_pol = *pol;
        link->l_trig = *trig;
        for (i = 0; i < link->l_dev_count; ++i) {
                reg = pci_conf_read(pc, link->l_devices[i],
                    PCI_INTERRUPT_REG);
                reg &= ~(PCI_INTERRUPT_LINE_MASK << PCI_INTERRUPT_LINE_SHIFT);
                reg |= link->l_irq << PCI_INTERRUPT_LINE_SHIFT;
                pci_conf_write(pc, link->l_devices[i],
                    PCI_INTERRUPT_REG, reg);
        }

done:
        ACPI_SERIAL_END(pci_link);

        return link->l_irq;
}

/*
 * This is gross, but we abuse the identify routine to perform one-time
 * SYSINIT() style initialization for the driver.
 */
static void
acpi_pci_link_init(struct acpi_pci_link_softc *sc)
{
        ACPI_BUFFER buf;

        /*
         * If the SCI is an ISA IRQ, add it to the bitmask of known good
         * ISA IRQs.
         *
         * XXX: If we are using the APIC, the SCI might have been
         * rerouted to an APIC pin in which case this is invalid.  However,
         * if we are using the APIC, we also shouldn't be having any PCI
         * interrupts routed via ISA IRQs, so this is probably ok.
         */
        if (AcpiGbl_FADT.SciInterrupt < NUM_ISA_INTERRUPTS)
                pci_link_bios_isa_irqs |= (1 << AcpiGbl_FADT.SciInterrupt);

        buf.Length = sizeof (sc->pl_name);
        buf.Pointer = sc->pl_name;

        if (ACPI_FAILURE(AcpiGetName(sc->pl_handle, ACPI_SINGLE_NAME, &buf)))
                snprintf(sc->pl_name, sizeof (sc->pl_name), "%s",
                    "ACPI link device");

        acpi_pci_link_attach(sc);
}

void *
acpi_pci_link_devbyhandle(ACPI_HANDLE handle)
{
        struct acpi_pci_link_softc *sc;

        TAILQ_FOREACH(sc, &acpi_pci_linkdevs, pl_list) {
                if (sc->pl_handle == handle)
                        return sc;
        }

        sc = malloc(sizeof (*sc), M_ACPI, M_WAITOK | M_ZERO);
        sc->pl_handle = handle;

        acpi_pci_link_init(sc);

        TAILQ_INSERT_TAIL(&acpi_pci_linkdevs, sc, pl_list);

        return (void *)sc;
}

void
acpi_pci_link_resume(void)
{
        struct acpi_pci_link_softc *sc;
        ACPI_BUFFER srsbuf;

        TAILQ_FOREACH(sc, &acpi_pci_linkdevs, pl_list) {
                ACPI_SERIAL_BEGIN(pci_link);
                if (ACPI_SUCCESS(acpi_pci_link_srs(sc, &srsbuf)))
                        ACPI_FREE(srsbuf.Pointer);
                ACPI_SERIAL_END(pci_link);
        }
}

ACPI_HANDLE
acpi_pci_link_handle(void *v)
{
        struct acpi_pci_link_softc *sc = v;

        return sc->pl_handle;
}

char *
acpi_pci_link_name(void *v)
{
        struct acpi_pci_link_softc *sc = v;

        return sc->pl_name;
}


/*
 * Append an ACPI_RESOURCE to an ACPI_BUFFER.
 *
 * Given a pointer to an ACPI_RESOURCE structure, expand the ACPI_BUFFER
 * provided to contain it.  If the ACPI_BUFFER is empty, allocate a sensible
 * backing block.  If the ACPI_RESOURCE is NULL, return an empty set of
 * resources.
 */
#define ACPI_INITIAL_RESOURCE_BUFFER_SIZE       512

static ACPI_STATUS
acpi_AppendBufferResource(ACPI_BUFFER *buf, ACPI_RESOURCE *res)
{
        ACPI_RESOURCE   *rp;
        void            *newp;

        /* Initialise the buffer if necessary. */
        if (buf->Pointer == NULL) {
        buf->Length = ACPI_INITIAL_RESOURCE_BUFFER_SIZE;
        if ((buf->Pointer = ACPI_ALLOCATE(buf->Length)) == NULL)
                return (AE_NO_MEMORY);
        rp = (ACPI_RESOURCE *)buf->Pointer;
        rp->Type =  ACPI_RESOURCE_TYPE_END_TAG;
        rp->Length = 0;
        }

        if (res == NULL)
                return AE_OK;

        /*
         * Scan the current buffer looking for the terminator.
         * This will either find the terminator or hit the end
         * of the buffer and return an error.
         */
        rp = (ACPI_RESOURCE *)buf->Pointer;
        for (;;) {
                /* Range check, don't go outside the buffer */
                if (rp >= (ACPI_RESOURCE *)((u_int8_t *)buf->Pointer +
                    buf->Length))
                        return AE_BAD_PARAMETER;
                if (rp->Type ==  ACPI_RESOURCE_TYPE_END_TAG || rp->Length == 0)
                        break;
                rp = ACPI_NEXT_RESOURCE(rp);
        }

        /*
         * Check the size of the buffer and expand if required.
         *
         * Required size is:
         *      size of existing resources before terminator +
         *      size of new resource and header +
         *      size of terminator.
         *
         * Note that this loop should really only run once, unless
         * for some reason we are stuffing a *really* huge resource.
         */
        while ((((u_int8_t *)rp - (u_int8_t *)buf->Pointer) +
            res->Length + ACPI_RS_SIZE_NO_DATA +
            ACPI_RS_SIZE_MIN) >= buf->Length) {
                if ((newp = ACPI_ALLOCATE(buf->Length * 2)) == NULL)
                        return AE_NO_MEMORY;
                memcpy(newp, buf->Pointer, buf->Length);
                rp = (ACPI_RESOURCE *)((u_int8_t *)newp +
                   ((u_int8_t *)rp - (u_int8_t *)buf->Pointer));
                ACPI_FREE(buf->Pointer);
                buf->Pointer = newp;
                buf->Length += buf->Length;
        }

        /* Insert the new resource. */
        memcpy(rp, res, res->Length);

        /* And add the terminator. */
        rp = ACPI_NEXT_RESOURCE(rp);
        rp->Type =  ACPI_RESOURCE_TYPE_END_TAG;
        rp->Length = 0;

        return AE_OK;
}