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		return rc;
42	/* No pin, exit */
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				return -EINVAL;
58		} else {
59			/* We found a P2P bridge, check if it has a node */
60			ppnode = pci_device_to_OF_node(ppdev);
61		}
62
63		/* Ok, we have found a parent with a device-node, hand over to
64		 * the OF parsing code.
65		 * We build a unit address from the linux device to be used for
66		 * resolution. Note that we use the linux bus number which may
67		 * not match your firmware bus numbering.
68		 * Fortunately, in most cases, interrupt-map-mask doesn't
69		 * include the bus number as part of the matching.
70		 * You should still be careful about that though if you intend
71		 * to rely on this function (you ship  a firmware that doesn't
72		 * create device nodes for all PCI devices).
73		 */
74		if (ppnode)
75			break;
76
77		/* We can only get here if we hit a P2P bridge with no node,
78		 * let's do standard swizzling and try again
79		 */
80		pin = pci_swizzle_interrupt_pin(pdev, pin);
81		pdev = ppdev;
82	}
83
84	out_irq->np = ppnode;
85	out_irq->args_count = 1;
86	out_irq->args[0] = pin;
87	laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
88	laddr[1] = laddr[2] = cpu_to_be32(0);
89	return of_irq_parse_raw(laddr, out_irq);
90}
91EXPORT_SYMBOL_GPL(of_irq_parse_pci);
92
93/**
94 * of_irq_parse_and_map_pci() - Decode a PCI irq from the device tree and map to a virq
95 * @dev: The pci device needing an irq
96 * @slot: PCI slot number; passed when used as map_irq callback. Unused
97 * @pin: PCI irq pin number; passed when used as map_irq callback. Unused
98 *
99 * @slot and @pin are unused, but included in the function so that this
100 * function can be used directly as the map_irq callback to pci_fixup_irqs().
101 */
102int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
103{
104	struct of_phandle_args oirq;
105	int ret;
106
107	ret = of_irq_parse_pci(dev, &oirq);
108	if (ret) {
109		dev_err(&dev->dev, "of_irq_parse_pci() failed with rc=%d\n", ret);
110		return 0; /* Proper return code 0 == NO_IRQ */
111	}
112
113	return irq_create_of_mapping(&oirq);
114}
115EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);
116
117