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#include <linux/kernel.h>
#include <linux/of_pci.h>
#include <linux/of_irq.h>
#include <linux/export.h>
#include <asm/prom.h>
/**
* of_irq_parse_pci - Resolve the interrupt for a PCI device
* @pdev: the device whose interrupt is to be resolved
* @out_irq: structure of_irq filled by this function
*
* This function resolves the PCI interrupt for a given PCI device. If a
* device-node exists for a given pci_dev, it will use normal OF tree
* walking. If not, it will implement standard swizzling and walk up the
* PCI tree until an device-node is found, at which point it will finish
* resolving using the OF tree walking.
*/
int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
{
struct device_node *dn, *ppnode;
struct pci_dev *ppdev;
u32 lspec;
__be32 lspec_be;
__be32 laddr[3];
u8 pin;
int rc;
/* Check if we have a device node, if yes, fallback to standard
* device tree parsing
*/
dn = pci_device_to_OF_node(pdev);
if (dn) {
rc = of_irq_parse_one(dn, 0, out_irq);
if (!rc)
return rc;
}
/* Ok, we don't, time to have fun. Let's start by building up an
* interrupt spec. we assume #interrupt-cells is 1, which is standard
* for PCI. If you do different, then don't use that routine.
*/
rc = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
if (rc != 0)
return rc;
/* No pin, exit */
if (pin == 0)
return -ENODEV;
/* Now we walk up the PCI tree */
lspec = pin;
for (;;) {
/* Get the pci_dev of our parent */
ppdev = pdev->bus->self;
/* Ouch, it's a host bridge... */
if (ppdev == NULL) {
ppnode = pci_bus_to_OF_node(pdev->bus);
/* No node for host bridge ? give up */
if (ppnode == NULL)
return -EINVAL;
} else {
/* We found a P2P bridge, check if it has a node */
ppnode = pci_device_to_OF_node(ppdev);
}
/* Ok, we have found a parent with a device-node, hand over to
* the OF parsing code.
* We build a unit address from the linux device to be used for
* resolution. Note that we use the linux bus number which may
* not match your firmware bus numbering.
* Fortunately, in most cases, interrupt-map-mask doesn't
* include the bus number as part of the matching.
* You should still be careful about that though if you intend
* to rely on this function (you ship a firmware that doesn't
* create device nodes for all PCI devices).
*/
if (ppnode)
break;
/* We can only get here if we hit a P2P bridge with no node,
* let's do standard swizzling and try again
*/
lspec = pci_swizzle_interrupt_pin(pdev, lspec);
pdev = ppdev;
}
out_irq->np = ppnode;
out_irq->args_count = 1;
out_irq->args[0] = lspec;
lspec_be = cpu_to_be32(lspec);
laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
laddr[1] = laddr[2] = cpu_to_be32(0);
return of_irq_parse_raw(laddr, out_irq);
}
EXPORT_SYMBOL_GPL(of_irq_parse_pci);
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