691cd0c2ee
I'm currently working on a port to a CPCI board with a MPC5200. When testing the PCI interrupt routing, I discovered the following: Even devices which don't use interrupts (-> PCI Spec.: Interrupt Pin Register is zero), get an interrupt assigned (this is at least true for most of the PPC-targets I looked at). The cause is pretty obvious in drivers/pci/setup-irq.c. I guess at least in an ideal world with correctly designed hardware, the code should rather look as in the patch below. Of course it doesn't hurt anybody to have an unuseable IRQ assigned to a PCI-to-PCI-bridge (or something alike), but to me it seems a bit strange. Please correct me, if I'm mislead. The patch below is tested on the above mentioned CPCI-MPC5200 board and is compiler tested with the latest git-repository kernel on x86. Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
66 lines
1.7 KiB
C
66 lines
1.7 KiB
C
/*
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* drivers/pci/setup-irq.c
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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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* Support routines for initializing a PCI subsystem.
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*/
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#include <linux/init.h>
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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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static void __init
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pdev_fixup_irq(struct pci_dev *dev,
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u8 (*swizzle)(struct pci_dev *, u8 *),
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int (*map_irq)(struct pci_dev *, u8, u8))
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{
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u8 pin, slot;
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int irq = 0;
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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 != 0) {
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/* Follow the chain of bridges, swizzling as we go. */
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slot = (*swizzle)(dev, &pin);
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irq = (*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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pr_debug("PCI: fixup irq: (%s) got %d\n",
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dev->dev.kobj.name, 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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pcibios_update_irq(dev, irq);
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}
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void __init
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pci_fixup_irqs(u8 (*swizzle)(struct pci_dev *, u8 *),
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int (*map_irq)(struct pci_dev *, u8, u8))
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{
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struct pci_dev *dev = NULL;
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while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
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pdev_fixup_irq(dev, swizzle, map_irq);
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}
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}
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