linux/drivers/of/of_pci.c
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   1#include <linux/kernel.h>
   2#include <linux/of_pci.h>
   3#include <linux/of_irq.h>
   4#include <asm/prom.h>
   5
   6/**
   7 * of_irq_map_pci - Resolve the interrupt for a PCI device
   8 * @pdev:       the device whose interrupt is to be resolved
   9 * @out_irq:    structure of_irq filled by this function
  10 *
  11 * This function resolves the PCI interrupt for a given PCI device. If a
  12 * device-node exists for a given pci_dev, it will use normal OF tree
  13 * walking. If not, it will implement standard swizzling and walk up the
  14 * PCI tree until an device-node is found, at which point it will finish
  15 * resolving using the OF tree walking.
  16 */
  17int of_irq_map_pci(struct pci_dev *pdev, struct of_irq *out_irq)
  18{
  19        struct device_node *dn, *ppnode;
  20        struct pci_dev *ppdev;
  21        u32 lspec;
  22        __be32 lspec_be;
  23        __be32 laddr[3];
  24        u8 pin;
  25        int rc;
  26
  27        /* Check if we have a device node, if yes, fallback to standard
  28         * device tree parsing
  29         */
  30        dn = pci_device_to_OF_node(pdev);
  31        if (dn) {
  32                rc = of_irq_map_one(dn, 0, out_irq);
  33                if (!rc)
  34                        return rc;
  35        }
  36
  37        /* Ok, we don't, time to have fun. Let's start by building up an
  38         * interrupt spec.  we assume #interrupt-cells is 1, which is standard
  39         * for PCI. If you do different, then don't use that routine.
  40         */
  41        rc = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
  42        if (rc != 0)
  43                return rc;
  44        /* No pin, exit */
  45        if (pin == 0)
  46                return -ENODEV;
  47
  48        /* Now we walk up the PCI tree */
  49        lspec = pin;
  50        for (;;) {
  51                /* Get the pci_dev of our parent */
  52                ppdev = pdev->bus->self;
  53
  54                /* Ouch, it's a host bridge... */
  55                if (ppdev == NULL) {
  56                        ppnode = pci_bus_to_OF_node(pdev->bus);
  57
  58                        /* No node for host bridge ? give up */
  59                        if (ppnode == NULL)
  60                                return -EINVAL;
  61                } else {
  62                        /* We found a P2P bridge, check if it has a node */
  63                        ppnode = pci_device_to_OF_node(ppdev);
  64                }
  65
  66                /* Ok, we have found a parent with a device-node, hand over to
  67                 * the OF parsing code.
  68                 * We build a unit address from the linux device to be used for
  69                 * resolution. Note that we use the linux bus number which may
  70                 * not match your firmware bus numbering.
  71                 * Fortunately, in most cases, interrupt-map-mask doesn't
  72                 * include the bus number as part of the matching.
  73                 * You should still be careful about that though if you intend
  74                 * to rely on this function (you ship  a firmware that doesn't
  75                 * create device nodes for all PCI devices).
  76                 */
  77                if (ppnode)
  78                        break;
  79
  80                /* We can only get here if we hit a P2P bridge with no node,
  81                 * let's do standard swizzling and try again
  82                 */
  83                lspec = pci_swizzle_interrupt_pin(pdev, lspec);
  84                pdev = ppdev;
  85        }
  86
  87        lspec_be = cpu_to_be32(lspec);
  88        laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
  89        laddr[1]  = laddr[2] = cpu_to_be32(0);
  90        return of_irq_map_raw(ppnode, &lspec_be, 1, laddr, out_irq);
  91}
  92EXPORT_SYMBOL_GPL(of_irq_map_pci);
  93