1#include <linux/kernel.h>
 2#include <linux/of_pci.h>
 3#include <linux/of_irq.h>
 4#include <asm/prom.h>
 5
 6/**
 7 * of_irq_map_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_map_pci(struct pci_dev *pdev, struct of_irq *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_map_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	lspec_be = cpu_to_be32(lspec);
88	laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
89	laddr[1]  = laddr[2] = cpu_to_be32(0);
90	return of_irq_map_raw(ppnode, &lspec_be, 1, laddr, out_irq);
91}
92EXPORT_SYMBOL_GPL(of_irq_map_pci);