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 */
of_irq_map_pci(struct pci_dev * pdev,struct of_irq * out_irq)18 int 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 }
93 EXPORT_SYMBOL_GPL(of_irq_map_pci);
94