drivers/of/of_pci_irq.c

   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  */
  17 int 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 }
  92 EXPORT_SYMBOL_GPL(of_irq_map_pci);