ioapic.c

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/*
 * IOAPIC/IOxAPIC/IOSAPIC driver
 *
 * Copyright (C) 2009 Fujitsu Limited.
 * (c) Copyright 2009 Hewlett-Packard Development Company, L.P.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

/*
 * This driver manages PCI I/O APICs added by hotplug after boot.  We try to
 * claim all I/O APIC PCI devices, but those present at boot were registered
 * when we parsed the ACPI MADT, so we'll fail when we try to re-register
 * them.
 */

#include <linux/pci.h>
#include <linux/module.h>
#include <linux/acpi.h>
#include <linux/slab.h>
#include <acpi/acpi_bus.h>

struct ioapic {
    acpi_handle handle;
    u32     gsi_base;
};

static int __devinit ioapic_probe(struct pci_dev *dev, const struct pci_device_id *ent)
{
    acpi_handle handle;
    acpi_status status;
    unsigned long long gsb;
    struct ioapic *ioapic;
    int ret;
    char *type;
    struct resource *res;

    handle = DEVICE_ACPI_HANDLE(&dev->dev);
    if (!handle)
        return -EINVAL;

    status = acpi_evaluate_integer(handle, "_GSB", NULL, &gsb);
    if (ACPI_FAILURE(status))
        return -EINVAL;

    /*
     * The previous code in acpiphp evaluated _MAT if _GSB failed, but
     * ACPI spec 4.0 sec 6.2.2 requires _GSB for hot-pluggable I/O APICs.
     */

    ioapic = kzalloc(sizeof(*ioapic), GFP_KERNEL);
    if (!ioapic)
        return -ENOMEM;

    ioapic->handle = handle;
    ioapic->gsi_base = (u32) gsb;

    if (dev->class == PCI_CLASS_SYSTEM_PIC_IOAPIC)
        type = "IOAPIC";
    else
        type = "IOxAPIC";

    ret = pci_enable_device(dev);
    if (ret < 0)
        goto exit_free;

    pci_set_master(dev);

    if (pci_request_region(dev, 0, type))
        goto exit_disable;

    res = &dev->resource[0];
    if (acpi_register_ioapic(ioapic->handle, res->start, ioapic->gsi_base))
        goto exit_release;

    pci_set_drvdata(dev, ioapic);
    dev_info(&dev->dev, "%s at %pR, GSI %u\n", type, res, ioapic->gsi_base);
    return 0;

exit_release:
    pci_release_region(dev, 0);
exit_disable:
    pci_disable_device(dev);
exit_free:
    kfree(ioapic);
    return -ENODEV;
}

static void __devexit ioapic_remove(struct pci_dev *dev)
{
    struct ioapic *ioapic = pci_get_drvdata(dev);

    acpi_unregister_ioapic(ioapic->handle, ioapic->gsi_base);
    pci_release_region(dev, 0);
    pci_disable_device(dev);
    kfree(ioapic);
}


static DEFINE_PCI_DEVICE_TABLE(ioapic_devices) = {
    { PCI_DEVICE_CLASS(PCI_CLASS_SYSTEM_PIC_IOAPIC, ~0) },
    { PCI_DEVICE_CLASS(PCI_CLASS_SYSTEM_PIC_IOXAPIC, ~0) },
    { }
};
MODULE_DEVICE_TABLE(pci, ioapic_devices);

static struct pci_driver ioapic_driver = {
    .name       = "ioapic",
    .id_table   = ioapic_devices,
    .probe      = ioapic_probe,
    .remove     = __devexit_p(ioapic_remove),
};

static int __init ioapic_init(void)
{
    return pci_register_driver(&ioapic_driver);
}

static void __exit ioapic_exit(void)
{
    pci_unregister_driver(&ioapic_driver);
}

module_init(ioapic_init);
module_exit(ioapic_exit);