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