of_pci_irq.c 3.6 KB

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  1. #include <linux/kernel.h>
  2. #include <linux/of_pci.h>
  3. #include <linux/of_irq.h>
  4. #include <linux/export.h>
  5. /**
  6. * of_irq_parse_pci - Resolve the interrupt for a PCI device
  7. * @pdev: the device whose interrupt is to be resolved
  8. * @out_irq: structure of_irq filled by this function
  9. *
  10. * This function resolves the PCI interrupt for a given PCI device. If a
  11. * device-node exists for a given pci_dev, it will use normal OF tree
  12. * walking. If not, it will implement standard swizzling and walk up the
  13. * PCI tree until an device-node is found, at which point it will finish
  14. * resolving using the OF tree walking.
  15. */
  16. int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
  17. {
  18. struct device_node *dn, *ppnode;
  19. struct pci_dev *ppdev;
  20. __be32 laddr[3];
  21. u8 pin;
  22. int rc;
  23. /* Check if we have a device node, if yes, fallback to standard
  24. * device tree parsing
  25. */
  26. dn = pci_device_to_OF_node(pdev);
  27. if (dn) {
  28. rc = of_irq_parse_one(dn, 0, out_irq);
  29. if (!rc)
  30. return rc;
  31. }
  32. /* Ok, we don't, time to have fun. Let's start by building up an
  33. * interrupt spec. we assume #interrupt-cells is 1, which is standard
  34. * for PCI. If you do different, then don't use that routine.
  35. */
  36. rc = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
  37. if (rc != 0)
  38. goto err;
  39. /* No pin, exit with no error message. */
  40. if (pin == 0)
  41. return -ENODEV;
  42. /* Now we walk up the PCI tree */
  43. for (;;) {
  44. /* Get the pci_dev of our parent */
  45. ppdev = pdev->bus->self;
  46. /* Ouch, it's a host bridge... */
  47. if (ppdev == NULL) {
  48. ppnode = pci_bus_to_OF_node(pdev->bus);
  49. /* No node for host bridge ? give up */
  50. if (ppnode == NULL) {
  51. rc = -EINVAL;
  52. goto err;
  53. }
  54. } else {
  55. /* We found a P2P bridge, check if it has a node */
  56. ppnode = pci_device_to_OF_node(ppdev);
  57. }
  58. /* Ok, we have found a parent with a device-node, hand over to
  59. * the OF parsing code.
  60. * We build a unit address from the linux device to be used for
  61. * resolution. Note that we use the linux bus number which may
  62. * not match your firmware bus numbering.
  63. * Fortunately, in most cases, interrupt-map-mask doesn't
  64. * include the bus number as part of the matching.
  65. * You should still be careful about that though if you intend
  66. * to rely on this function (you ship a firmware that doesn't
  67. * create device nodes for all PCI devices).
  68. */
  69. if (ppnode)
  70. break;
  71. /* We can only get here if we hit a P2P bridge with no node,
  72. * let's do standard swizzling and try again
  73. */
  74. pin = pci_swizzle_interrupt_pin(pdev, pin);
  75. pdev = ppdev;
  76. }
  77. out_irq->np = ppnode;
  78. out_irq->args_count = 1;
  79. out_irq->args[0] = pin;
  80. laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
  81. laddr[1] = laddr[2] = cpu_to_be32(0);
  82. rc = of_irq_parse_raw(laddr, out_irq);
  83. if (rc)
  84. goto err;
  85. return 0;
  86. err:
  87. dev_err(&pdev->dev, "of_irq_parse_pci() failed with rc=%d\n", rc);
  88. return rc;
  89. }
  90. EXPORT_SYMBOL_GPL(of_irq_parse_pci);
  91. /**
  92. * of_irq_parse_and_map_pci() - Decode a PCI irq from the device tree and map to a virq
  93. * @dev: The pci device needing an irq
  94. * @slot: PCI slot number; passed when used as map_irq callback. Unused
  95. * @pin: PCI irq pin number; passed when used as map_irq callback. Unused
  96. *
  97. * @slot and @pin are unused, but included in the function so that this
  98. * function can be used directly as the map_irq callback to pci_fixup_irqs().
  99. */
  100. int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
  101. {
  102. struct of_phandle_args oirq;
  103. int ret;
  104. ret = of_irq_parse_pci(dev, &oirq);
  105. if (ret)
  106. return 0; /* Proper return code 0 == NO_IRQ */
  107. return irq_create_of_mapping(&oirq);
  108. }
  109. EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);