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	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_parse_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	out_irq->np = ppnode;
 88	out_irq->args_count = 1;
 89	out_irq->args[0] = lspec;
 90	lspec_be = cpu_to_be32(lspec);
 91	laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
 92	laddr[1] = laddr[2] = cpu_to_be32(0);
 93	return of_irq_parse_raw(laddr, out_irq);
 94}
 95EXPORT_SYMBOL_GPL(of_irq_parse_pci);
 96
 97/**
 98 * of_irq_parse_and_map_pci() - Decode a PCI irq from the device tree and map to a virq
 99 * @dev: The pci device needing an irq
100 * @slot: PCI slot number; passed when used as map_irq callback. Unused
101 * @pin: PCI irq pin number; passed when used as map_irq callback. Unused
102 *
103 * @slot and @pin are unused, but included in the function so that this
104 * function can be used directly as the map_irq callback to pci_fixup_irqs().
105 */
106int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
107{
108	struct of_phandle_args oirq;
109	int ret;
110
111	ret = of_irq_parse_pci(dev, &oirq);
112	if (ret) {
113		dev_err(&dev->dev, "of_irq_parse_pci() failed with rc=%d\n", ret);
114		return 0; /* Proper return code 0 == NO_IRQ */
115	}
116
117	return irq_create_of_mapping(&oirq);
118}
119EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);
120