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
  20void __weak pcibios_update_irq(struct pci_dev *dev, int irq)
  21{
  22        dev_dbg(&dev->dev, "assigning IRQ %02d\n", irq);
  23        pci_write_config_byte(dev, PCI_INTERRUPT_LINE, irq);
  24}
  25
  26static void
  27pdev_fixup_irq(struct pci_dev *dev,
  28               u8 (*swizzle)(struct pci_dev *, u8 *),
  29               int (*map_irq)(const struct pci_dev *, u8, u8))
  30{
  31        u8 pin, slot;
  32        int irq = 0;
  33
  34        /* If this device is not on the primary bus, we need to figure out
  35           which interrupt pin it will come in on.   We know which slot it
  36           will come in on 'cos that slot is where the bridge is.   Each
  37           time the interrupt line passes through a PCI-PCI bridge we must
  38           apply the swizzle function.  */
  39
  40        pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
  41        /* Cope with illegal. */
  42        if (pin > 4)
  43                pin = 1;
  44
  45        if (pin != 0) {
  46                /* Follow the chain of bridges, swizzling as we go.  */
  47                slot = (*swizzle)(dev, &pin);
  48
  49                irq = (*map_irq)(dev, slot, pin);
  50                if (irq == -1)
  51                        irq = 0;
  52        }
  53        dev->irq = irq;
  54
  55        dev_dbg(&dev->dev, "fixup irq: got %d\n", dev->irq);
  56
  57        /* Always tell the device, so the driver knows what is
  58           the real IRQ to use; the device does not use it. */
  59        pcibios_update_irq(dev, irq);
  60}
  61
  62void
  63pci_fixup_irqs(u8 (*swizzle)(struct pci_dev *, u8 *),
  64               int (*map_irq)(const struct pci_dev *, u8, u8))
  65{
  66        struct pci_dev *dev = NULL;
  67        for_each_pci_dev(dev)
  68                pdev_fixup_irq(dev, swizzle, map_irq);
  69}
  70
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