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62 lines
1.6 KiB
62 lines
1.6 KiB
// 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 ([email protected]) |
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* David Mosberger ([email protected]) |
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* David Miller ([email protected]) |
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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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