63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Support routines for initializing a PCI subsystem
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*
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* Extruded from code written by
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* Dave Rusling (david.rusling@reo.mts.dec.com)
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* David Mosberger (davidm@cs.arizona.edu)
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* David Miller (davem@redhat.com)
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*/
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#include <linux/kernel.h>
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#include <linux/pci.h>
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#include <linux/errno.h>
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#include <linux/ioport.h>
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#include <linux/cache.h>
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#include "pci.h"
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void pci_assign_irq(struct pci_dev *dev)
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{
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u8 pin;
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u8 slot = -1;
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int irq = 0;
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struct pci_host_bridge *hbrg = pci_find_host_bridge(dev->bus);
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if (!(hbrg->map_irq)) {
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pci_dbg(dev, "runtime IRQ mapping not provided by arch\n");
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return;
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}
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/* If this device is not on the primary bus, we need to figure out
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which interrupt pin it will come in on. We know which slot it
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will come in on 'cos that slot is where the bridge is. Each
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time the interrupt line passes through a PCI-PCI bridge we must
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apply the swizzle function. */
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pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
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/* Cope with illegal. */
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if (pin > 4)
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pin = 1;
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if (pin) {
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/* Follow the chain of bridges, swizzling as we go. */
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if (hbrg->swizzle_irq)
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slot = (*(hbrg->swizzle_irq))(dev, &pin);
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/*
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* If a swizzling function is not used map_irq must
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* ignore slot
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*/
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irq = (*(hbrg->map_irq))(dev, slot, pin);
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if (irq == -1)
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irq = 0;
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}
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dev->irq = irq;
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pci_dbg(dev, "assign IRQ: got %d\n", dev->irq);
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/* Always tell the device, so the driver knows what is
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the real IRQ to use; the device does not use it. */
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pci_write_config_byte(dev, PCI_INTERRUPT_LINE, irq);
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}
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