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 */
 17int 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		goto err;
 42	/* No pin, exit with no error message. */
 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				rc = -EINVAL;
 58				goto err;
 59			}
 60		} else {
 61			/* We found a P2P bridge, check if it has a node */
 62			ppnode = pci_device_to_OF_node(ppdev);
 63		}
 64
 65		/* Ok, we have found a parent with a device-node, hand over to
 66		 * the OF parsing code.
 67		 * We build a unit address from the linux device to be used for
 68		 * resolution. Note that we use the linux bus number which may
 69		 * not match your firmware bus numbering.
 70		 * Fortunately, in most cases, interrupt-map-mask doesn't
 71		 * include the bus number as part of the matching.
 72		 * You should still be careful about that though if you intend
 73		 * to rely on this function (you ship  a firmware that doesn't
 74		 * create device nodes for all PCI devices).
 75		 */
 76		if (ppnode)
 77			break;
 78
 79		/* We can only get here if we hit a P2P bridge with no node,
 80		 * let's do standard swizzling and try again
 81		 */
 82		pin = pci_swizzle_interrupt_pin(pdev, pin);
 83		pdev = ppdev;
 84	}
 85
 86	out_irq->np = ppnode;
 87	out_irq->args_count = 1;
 88	out_irq->args[0] = pin;
 89	laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
 90	laddr[1] = laddr[2] = cpu_to_be32(0);
 91	rc = of_irq_parse_raw(laddr, out_irq);
 92	if (rc)
 93		goto err;
 94	return 0;
 95err:
 96	dev_err(&pdev->dev, "of_irq_parse_pci() failed with rc=%d\n", rc);
 97	return rc;
 98}
 99EXPORT_SYMBOL_GPL(of_irq_parse_pci);
100
101/**
102 * of_irq_parse_and_map_pci() - Decode a PCI irq from the device tree and map to a virq
103 * @dev: The pci device needing an irq
104 * @slot: PCI slot number; passed when used as map_irq callback. Unused
105 * @pin: PCI irq pin number; passed when used as map_irq callback. Unused
106 *
107 * @slot and @pin are unused, but included in the function so that this
108 * function can be used directly as the map_irq callback to pci_fixup_irqs().
109 */
110int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
111{
112	struct of_phandle_args oirq;
113	int ret;
114
115	ret = of_irq_parse_pci(dev, &oirq);
116	if (ret)
117		return 0; /* Proper return code 0 == NO_IRQ */
118
119	return irq_create_of_mapping(&oirq);
120}
121EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);
122