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