of_pci_irq.c

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#include <linux/kernel.h>
#include <linux/of_pci.h>
#include <linux/of_irq.h>
#include <linux/export.h>
#include <asm/prom.h>

int of_irq_map_pci(const struct pci_dev *pdev, struct of_irq *out_irq)
{
    struct device_node *dn, *ppnode;
    struct pci_dev *ppdev;
    u32 lspec;
    __be32 lspec_be;
    __be32 laddr[3];
    u8 pin;
    int rc;

    /* Check if we have a device node, if yes, fallback to standard
     * device tree parsing
     */
    dn = pci_device_to_OF_node(pdev);
    if (dn) {
        rc = of_irq_map_one(dn, 0, out_irq);
        if (!rc)
            return rc;
    }

    /* Ok, we don't, time to have fun. Let's start by building up an
     * interrupt spec.  we assume #interrupt-cells is 1, which is standard
     * for PCI. If you do different, then don't use that routine.
     */
    rc = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
    if (rc != 0)
        return rc;
    /* No pin, exit */
    if (pin == 0)
        return -ENODEV;

    /* Now we walk up the PCI tree */
    lspec = pin;
    for (;;) {
        /* Get the pci_dev of our parent */
        ppdev = pdev->bus->self;

        /* Ouch, it's a host bridge... */
        if (ppdev == NULL) {
            ppnode = pci_bus_to_OF_node(pdev->bus);

            /* No node for host bridge ? give up */
            if (ppnode == NULL)
                return -EINVAL;
        } else {
            /* We found a P2P bridge, check if it has a node */
            ppnode = pci_device_to_OF_node(ppdev);
        }

        /* Ok, we have found a parent with a device-node, hand over to
         * the OF parsing code.
         * We build a unit address from the linux device to be used for
         * resolution. Note that we use the linux bus number which may
         * not match your firmware bus numbering.
         * Fortunately, in most cases, interrupt-map-mask doesn't
         * include the bus number as part of the matching.
         * You should still be careful about that though if you intend
         * to rely on this function (you ship  a firmware that doesn't
         * create device nodes for all PCI devices).
         */
        if (ppnode)
            break;

        /* We can only get here if we hit a P2P bridge with no node,
         * let's do standard swizzling and try again
         */
        lspec = pci_swizzle_interrupt_pin(pdev, lspec);
        pdev = ppdev;
    }

    lspec_be = cpu_to_be32(lspec);
    laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
    laddr[1]  = laddr[2] = cpu_to_be32(0);
    return of_irq_map_raw(ppnode, &lspec_be, 1, laddr, out_irq);
}
EXPORT_SYMBOL_GPL(of_irq_map_pci);