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
   6 /**
   7  * of_irq_parse_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_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
  18 {
  19         struct device_node *dn, *ppnode;
  20         struct pci_dev *ppdev;
  21         __be32 laddr[3];
  22         u8 pin;
  23         int rc;
  24
  25         /* Check if we have a device node, if yes, fallback to standard
  26          * device tree parsing
  27          */
  28         dn = pci_device_to_OF_node(pdev);
  29         if (dn) {
  30                 rc = of_irq_parse_one(dn, 0, out_irq);
  31                 if (!rc)
  32                         return rc;
  33         }
  34
  35         /* Ok, we don't, time to have fun. Let's start by building up an
  36          * interrupt spec.  we assume #interrupt-cells is 1, which is standard
  37          * for PCI. If you do different, then don't use that routine.
  38          */
  39         rc = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
  40         if (rc != 0)
  41                 return rc;
  42         /* No pin, exit */
  43         if (pin == 0)
  44                 return -ENODEV;
  45
  46         /* Now we walk up the PCI tree */
  47         for (;;) {
  48                 /* Get the pci_dev of our parent */
  49                 ppdev = pdev->bus->self;
  50
  51                 /* Ouch, it's a host bridge... */
  52                 if (ppdev == NULL) {
  53                         ppnode = pci_bus_to_OF_node(pdev->bus);
  54
  55                         /* No node for host bridge ? give up */
  56                         if (ppnode == NULL)
  57                                 return -EINVAL;
  58                 } else {
  59                         /* We found a P2P bridge, check if it has a node */
  60                         ppnode = pci_device_to_OF_node(ppdev);
  61                 }
  62
  63                 /* Ok, we have found a parent with a device-node, hand over to
  64                  * the OF parsing code.
  65                  * We build a unit address from the linux device to be used for
  66                  * resolution. Note that we use the linux bus number which may
  67                  * not match your firmware bus numbering.
  68                  * Fortunately, in most cases, interrupt-map-mask doesn't
  69                  * include the bus number as part of the matching.
  70                  * You should still be careful about that though if you intend
  71                  * to rely on this function (you ship  a firmware that doesn't
  72                  * create device nodes for all PCI devices).
  73                  */
  74                 if (ppnode)
  75                         break;
  76
  77                 /* We can only get here if we hit a P2P bridge with no node,
  78                  * let's do standard swizzling and try again
  79                  */
  80                 pin = pci_swizzle_interrupt_pin(pdev, pin);
  81                 pdev = ppdev;
  82         }
  83
  84         out_irq->np = ppnode;
  85         out_irq->args_count = 1;
  86         out_irq->args[0] = pin;
  87         laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
  88         laddr[1] = laddr[2] = cpu_to_be32(0);
  89         return of_irq_parse_raw(laddr, out_irq);
  90 }
  91 EXPORT_SYMBOL_GPL(of_irq_parse_pci);
  92
  93 /**
  94  * of_irq_parse_and_map_pci() - Decode a PCI irq from the device tree and map to a virq
  95  * @dev: The pci device needing an irq
  96  * @slot: PCI slot number; passed when used as map_irq callback. Unused
  97  * @pin: PCI irq pin number; passed when used as map_irq callback. Unused
  98  *
  99  * @slot and @pin are unused, but included in the function so that this
 100  * function can be used directly as the map_irq callback to pci_fixup_irqs().
 101  */
 102 int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
 103 {
 104         struct of_phandle_args oirq;
 105         int ret;
 106
 107         ret = of_irq_parse_pci(dev, &oirq);
 108         if (ret) {
 109                 dev_err(&dev->dev, "of_irq_parse_pci() failed with rc=%d\n", ret);
 110                 return 0; /* Proper return code 0 == NO_IRQ */
 111         }
 112
 113         return irq_create_of_mapping(&oirq);
 114 }
 115 EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);
 116