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
123