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 */
of_irq_parse_pci(const struct pci_dev * pdev,struct of_phandle_args * out_irq)17 int 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;
95 err:
96 if (rc == -ENOENT) {
97 dev_warn(&pdev->dev,
98 "%s: no interrupt-map found, INTx interrupts not available\n",
99 __func__);
100 pr_warn_once("%s: possibly some PCI slots don't have level triggered interrupts capability\n",
101 __func__);
102 } else {
103 dev_err(&pdev->dev, "%s: failed with rc=%d\n", __func__, rc);
104 }
105 return rc;
106 }
107 EXPORT_SYMBOL_GPL(of_irq_parse_pci);
108
109 /**
110 * of_irq_parse_and_map_pci() - Decode a PCI irq from the device tree and map to a virq
111 * @dev: The pci device needing an irq
112 * @slot: PCI slot number; passed when used as map_irq callback. Unused
113 * @pin: PCI irq pin number; passed when used as map_irq callback. Unused
114 *
115 * @slot and @pin are unused, but included in the function so that this
116 * function can be used directly as the map_irq callback to
117 * pci_assign_irq() and struct pci_host_bridge.map_irq pointer
118 */
of_irq_parse_and_map_pci(const struct pci_dev * dev,u8 slot,u8 pin)119 int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
120 {
121 struct of_phandle_args oirq;
122 int ret;
123
124 ret = of_irq_parse_pci(dev, &oirq);
125 if (ret)
126 return 0; /* Proper return code 0 == NO_IRQ */
127
128 return irq_create_of_mapping(&oirq);
129 }
130 EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);
131
132