linux/drivers/pci/setup-irq.c
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   1/*
   2 *      drivers/pci/setup-irq.c
   3 *
   4 * Extruded from code written by
   5 *      Dave Rusling (david.rusling@reo.mts.dec.com)
   6 *      David Mosberger (davidm@cs.arizona.edu)
   7 *      David Miller (davem@redhat.com)
   8 *
   9 * Support routines for initializing a PCI subsystem.
  10 */
  11
  12
  13#include <linux/init.h>
  14#include <linux/kernel.h>
  15#include <linux/pci.h>
  16#include <linux/errno.h>
  17#include <linux/ioport.h>
  18#include <linux/cache.h>
  19
  20
  21static void __init
  22pdev_fixup_irq(struct pci_dev *dev,
  23               u8 (*swizzle)(struct pci_dev *, u8 *),
  24               int (*map_irq)(const struct pci_dev *, u8, u8))
  25{
  26        u8 pin, slot;
  27        int irq = 0;
  28
  29        /* If this device is not on the primary bus, we need to figure out
  30           which interrupt pin it will come in on.   We know which slot it
  31           will come in on 'cos that slot is where the bridge is.   Each
  32           time the interrupt line passes through a PCI-PCI bridge we must
  33           apply the swizzle function.  */
  34
  35        pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
  36        /* Cope with illegal. */
  37        if (pin > 4)
  38                pin = 1;
  39
  40        if (pin != 0) {
  41                /* Follow the chain of bridges, swizzling as we go.  */
  42                slot = (*swizzle)(dev, &pin);
  43
  44                irq = (*map_irq)(dev, slot, pin);
  45                if (irq == -1)
  46                        irq = 0;
  47        }
  48        dev->irq = irq;
  49
  50        dev_dbg(&dev->dev, "fixup irq: got %d\n", dev->irq);
  51
  52        /* Always tell the device, so the driver knows what is
  53           the real IRQ to use; the device does not use it. */
  54        pcibios_update_irq(dev, irq);
  55}
  56
  57void __init
  58pci_fixup_irqs(u8 (*swizzle)(struct pci_dev *, u8 *),
  59               int (*map_irq)(const struct pci_dev *, u8, u8))
  60{
  61        struct pci_dev *dev = NULL;
  62        for_each_pci_dev(dev)
  63                pdev_fixup_irq(dev, swizzle, map_irq);
  64}
  65
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