1#include <linux/kernel.h>
2#include <linux/of_pci.h>
3#include <linux/of_irq.h>
4#include <linux/export.h>
5#include <asm/prom.h>
6
7/**
8 * of_irq_map_pci - Resolve the interrupt for a PCI device
9 * @pdev:       the device whose interrupt is to be resolved
10 * @out_irq:    structure of_irq filled by this function
11 *
12 * This function resolves the PCI interrupt for a given PCI device. If a
13 * device-node exists for a given pci_dev, it will use normal OF tree
14 * walking. If not, it will implement standard swizzling and walk up the
15 * PCI tree until an device-node is found, at which point it will finish
16 * resolving using the OF tree walking.
17 */
18int of_irq_map_pci(struct pci_dev *pdev, struct of_irq *out_irq)
19{
20	struct device_node *dn, *ppnode;
21	struct pci_dev *ppdev;
22	u32 lspec;
23	__be32 lspec_be;
24	__be32 laddr[3];
25	u8 pin;
26	int rc;
27
28	/* Check if we have a device node, if yes, fallback to standard
29	 * device tree parsing
30	 */
31	dn = pci_device_to_OF_node(pdev);
32	if (dn) {
33		rc = of_irq_map_one(dn, 0, out_irq);
34		if (!rc)
35			return rc;
36	}
37
38	/* Ok, we don't, time to have fun. Let's start by building up an
39	 * interrupt spec.  we assume #interrupt-cells is 1, which is standard
40	 * for PCI. If you do different, then don't use that routine.
41	 */
42	rc = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
43	if (rc != 0)
44		return rc;
45	/* No pin, exit */
46	if (pin == 0)
47		return -ENODEV;
48
49	/* Now we walk up the PCI tree */
50	lspec = pin;
51	for (;;) {
52		/* Get the pci_dev of our parent */
53		ppdev = pdev->bus->self;
54
55		/* Ouch, it's a host bridge... */
56		if (ppdev == NULL) {
57			ppnode = pci_bus_to_OF_node(pdev->bus);
58
59			/* No node for host bridge ? give up */
60			if (ppnode == NULL)
61				return -EINVAL;
62		} else {
63			/* We found a P2P bridge, check if it has a node */
64			ppnode = pci_device_to_OF_node(ppdev);
65		}
66
67		/* Ok, we have found a parent with a device-node, hand over to
68		 * the OF parsing code.
69		 * We build a unit address from the linux device to be used for
70		 * resolution. Note that we use the linux bus number which may
71		 * not match your firmware bus numbering.
72		 * Fortunately, in most cases, interrupt-map-mask doesn't
73		 * include the bus number as part of the matching.
74		 * You should still be careful about that though if you intend
75		 * to rely on this function (you ship  a firmware that doesn't
76		 * create device nodes for all PCI devices).
77		 */
78		if (ppnode)
79			break;
80
81		/* We can only get here if we hit a P2P bridge with no node,
82		 * let's do standard swizzling and try again
83		 */
84		lspec = pci_swizzle_interrupt_pin(pdev, lspec);
85		pdev = ppdev;
86	}
87
88	lspec_be = cpu_to_be32(lspec);
89	laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
90	laddr[1]  = laddr[2] = cpu_to_be32(0);
91	return of_irq_map_raw(ppnode, &lspec_be, 1, laddr, out_irq);
92}
93EXPORT_SYMBOL_GPL(of_irq_map_pci);
94