processor_driver.c

Go to the documentation of this file.

/*
 * acpi_processor.c - ACPI Processor Driver ($Revision: 71 $)
 *
 *  Copyright (C) 2001, 2002 Andy Grover <[email protected]>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <[email protected]>
 *  Copyright (C) 2004       Dominik Brodowski <[email protected]>
 *  Copyright (C) 2004  Anil S Keshavamurthy <[email protected]>
 *              - Added processor hotplug support
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *  TBD:
 *  1. Make # power states dynamic.
 *  2. Support duty_cycle values that span bit 4.
 *  3. Optimize by having scheduler determine business instead of
 *     having us try to calculate it here.
 *  4. Need C1 timing -- must modify kernel (IRQ handler) to get this.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/pci.h>
#include <linux/pm.h>
#include <linux/cpufreq.h>
#include <linux/cpu.h>
#include <linux/dmi.h>
#include <linux/moduleparam.h>
#include <linux/cpuidle.h>
#include <linux/slab.h>

#include <asm/io.h>
#include <asm/cpu.h>
#include <asm/delay.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <asm/smp.h>
#include <asm/acpi.h>

#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <acpi/processor.h>

#define PREFIX "ACPI: "

#define ACPI_PROCESSOR_CLASS        "processor"
#define ACPI_PROCESSOR_DEVICE_NAME  "Processor"
#define ACPI_PROCESSOR_FILE_INFO    "info"
#define ACPI_PROCESSOR_FILE_THROTTLING  "throttling"
#define ACPI_PROCESSOR_FILE_LIMIT   "limit"
#define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
#define ACPI_PROCESSOR_NOTIFY_POWER 0x81
#define ACPI_PROCESSOR_NOTIFY_THROTTLING    0x82
#define ACPI_PROCESSOR_DEVICE_HID   "ACPI0007"

#define ACPI_PROCESSOR_LIMIT_USER   0
#define ACPI_PROCESSOR_LIMIT_THERMAL    1

#define _COMPONENT      ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_driver");

MODULE_AUTHOR("Paul Diefenbaugh");
MODULE_DESCRIPTION("ACPI Processor Driver");
MODULE_LICENSE("GPL");

static int acpi_processor_add(struct acpi_device *device);
static int acpi_processor_remove(struct acpi_device *device, int type);
static void acpi_processor_notify(struct acpi_device *device, u32 event);
static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr);
static int acpi_processor_handle_eject(struct acpi_processor *pr);
static int acpi_processor_start(struct acpi_processor *pr);

static const struct acpi_device_id processor_device_ids[] = {
    {ACPI_PROCESSOR_OBJECT_HID, 0},
    {ACPI_PROCESSOR_DEVICE_HID, 0},
    {"", 0},
};
MODULE_DEVICE_TABLE(acpi, processor_device_ids);

static SIMPLE_DEV_PM_OPS(acpi_processor_pm,
             acpi_processor_suspend, acpi_processor_resume);

static struct acpi_driver acpi_processor_driver = {
    .name = "processor",
    .class = ACPI_PROCESSOR_CLASS,
    .ids = processor_device_ids,
    .ops = {
        .add = acpi_processor_add,
        .remove = acpi_processor_remove,
        .notify = acpi_processor_notify,
        },
    .drv.pm = &acpi_processor_pm,
};

#define INSTALL_NOTIFY_HANDLER      1
#define UNINSTALL_NOTIFY_HANDLER    2

DEFINE_PER_CPU(struct acpi_processor *, processors);
EXPORT_PER_CPU_SYMBOL(processors);

struct acpi_processor_errata errata __read_mostly;

/* --------------------------------------------------------------------------
                                Errata Handling
   -------------------------------------------------------------------------- */

static int acpi_processor_errata_piix4(struct pci_dev *dev)
{
    u8 value1 = 0;
    u8 value2 = 0;


    if (!dev)
        return -EINVAL;

    /*
     * Note that 'dev' references the PIIX4 ACPI Controller.
     */

    switch (dev->revision) {
    case 0:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found PIIX4 A-step\n"));
        break;
    case 1:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found PIIX4 B-step\n"));
        break;
    case 2:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found PIIX4E\n"));
        break;
    case 3:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found PIIX4M\n"));
        break;
    default:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found unknown PIIX4\n"));
        break;
    }

    switch (dev->revision) {

    case 0:     /* PIIX4 A-step */
    case 1:     /* PIIX4 B-step */
        /*
         * See specification changes #13 ("Manual Throttle Duty Cycle")
         * and #14 ("Enabling and Disabling Manual Throttle"), plus
         * erratum #5 ("STPCLK# Deassertion Time") from the January
         * 2002 PIIX4 specification update.  Applies to only older
         * PIIX4 models.
         */
        errata.piix4.throttle = 1;

    case 2:     /* PIIX4E */
    case 3:     /* PIIX4M */
        /*
         * See erratum #18 ("C3 Power State/BMIDE and Type-F DMA
         * Livelock") from the January 2002 PIIX4 specification update.
         * Applies to all PIIX4 models.
         */

        /*
         * BM-IDE
         * ------
         * Find the PIIX4 IDE Controller and get the Bus Master IDE
         * Status register address.  We'll use this later to read
         * each IDE controller's DMA status to make sure we catch all
         * DMA activity.
         */
        dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
                     PCI_DEVICE_ID_INTEL_82371AB,
                     PCI_ANY_ID, PCI_ANY_ID, NULL);
        if (dev) {
            errata.piix4.bmisx = pci_resource_start(dev, 4);
            pci_dev_put(dev);
        }

        /*
         * Type-F DMA
         * ----------
         * Find the PIIX4 ISA Controller and read the Motherboard
         * DMA controller's status to see if Type-F (Fast) DMA mode
         * is enabled (bit 7) on either channel.  Note that we'll
         * disable C3 support if this is enabled, as some legacy
         * devices won't operate well if fast DMA is disabled.
         */
        dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
                     PCI_DEVICE_ID_INTEL_82371AB_0,
                     PCI_ANY_ID, PCI_ANY_ID, NULL);
        if (dev) {
            pci_read_config_byte(dev, 0x76, &value1);
            pci_read_config_byte(dev, 0x77, &value2);
            if ((value1 & 0x80) || (value2 & 0x80))
                errata.piix4.fdma = 1;
            pci_dev_put(dev);
        }

        break;
    }

    if (errata.piix4.bmisx)
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Bus master activity detection (BM-IDE) erratum enabled\n"));
    if (errata.piix4.fdma)
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Type-F DMA livelock erratum (C3 disabled)\n"));

    return 0;
}

static int acpi_processor_errata(struct acpi_processor *pr)
{
    int result = 0;
    struct pci_dev *dev = NULL;


    if (!pr)
        return -EINVAL;

    /*
     * PIIX4
     */
    dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
                 PCI_DEVICE_ID_INTEL_82371AB_3, PCI_ANY_ID,
                 PCI_ANY_ID, NULL);
    if (dev) {
        result = acpi_processor_errata_piix4(dev);
        pci_dev_put(dev);
    }

    return result;
}

/* --------------------------------------------------------------------------
                                 Driver Interface
   -------------------------------------------------------------------------- */

static int acpi_processor_get_info(struct acpi_device *device)
{
    acpi_status status = 0;
    union acpi_object object = { 0 };
    struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
    struct acpi_processor *pr;
    int cpu_index, device_declaration = 0;
    static int cpu0_initialized;

    pr = acpi_driver_data(device);
    if (!pr)
        return -EINVAL;

    if (num_online_cpus() > 1)
        errata.smp = TRUE;

    acpi_processor_errata(pr);

    /*
     * Check to see if we have bus mastering arbitration control.  This
     * is required for proper C3 usage (to maintain cache coherency).
     */
    if (acpi_gbl_FADT.pm2_control_block && acpi_gbl_FADT.pm2_control_length) {
        pr->flags.bm_control = 1;
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Bus mastering arbitration control present\n"));
    } else
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "No bus mastering arbitration control\n"));

    if (!strcmp(acpi_device_hid(device), ACPI_PROCESSOR_OBJECT_HID)) {
        /* Declared with "Processor" statement; match ProcessorID */
        status = acpi_evaluate_object(pr->handle, NULL, NULL, &buffer);
        if (ACPI_FAILURE(status)) {
            printk(KERN_ERR PREFIX "Evaluating processor object\n");
            return -ENODEV;
        }

        /*
         * TBD: Synch processor ID (via LAPIC/LSAPIC structures) on SMP.
         *      >>> 'acpi_get_processor_id(acpi_id, &id)' in
         *      arch/xxx/acpi.c
         */
        pr->acpi_id = object.processor.proc_id;
    } else {
        /*
         * Declared with "Device" statement; match _UID.
         * Note that we don't handle string _UIDs yet.
         */
        unsigned long long value;
        status = acpi_evaluate_integer(pr->handle, METHOD_NAME__UID,
                        NULL, &value);
        if (ACPI_FAILURE(status)) {
            printk(KERN_ERR PREFIX
                "Evaluating processor _UID [%#x]\n", status);
            return -ENODEV;
        }
        device_declaration = 1;
        pr->acpi_id = value;
    }
    cpu_index = acpi_get_cpuid(pr->handle, device_declaration, pr->acpi_id);

    /* Handle UP system running SMP kernel, with no LAPIC in MADT */
    if (!cpu0_initialized && (cpu_index == -1) &&
        (num_online_cpus() == 1)) {
        cpu_index = 0;
    }

    cpu0_initialized = 1;

    pr->id = cpu_index;

    /*
     *  Extra Processor objects may be enumerated on MP systems with
     *  less than the max # of CPUs. They should be ignored _iff
     *  they are physically not present.
     */
    if (pr->id == -1) {
        if (ACPI_FAILURE(acpi_processor_hotadd_init(pr)))
            return -ENODEV;
    }
    /*
     * On some boxes several processors use the same processor bus id.
     * But they are located in different scope. For example:
     * \_SB.SCK0.CPU0
     * \_SB.SCK1.CPU0
     * Rename the processor device bus id. And the new bus id will be
     * generated as the following format:
     * CPU+CPU ID.
     */
    sprintf(acpi_device_bid(device), "CPU%X", pr->id);
    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Processor [%d:%d]\n", pr->id,
              pr->acpi_id));

    if (!object.processor.pblk_address)
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No PBLK (NULL address)\n"));
    else if (object.processor.pblk_length != 6)
        printk(KERN_ERR PREFIX "Invalid PBLK length [%d]\n",
                object.processor.pblk_length);
    else {
        pr->throttling.address = object.processor.pblk_address;
        pr->throttling.duty_offset = acpi_gbl_FADT.duty_offset;
        pr->throttling.duty_width = acpi_gbl_FADT.duty_width;

        pr->pblk = object.processor.pblk_address;

        /*
         * We don't care about error returns - we just try to mark
         * these reserved so that nobody else is confused into thinking
         * that this region might be unused..
         *
         * (In particular, allocating the IO range for Cardbus)
         */
        request_region(pr->throttling.address, 6, "ACPI CPU throttle");
    }

    /*
     * If ACPI describes a slot number for this CPU, we can use it
     * ensure we get the right value in the "physical id" field
     * of /proc/cpuinfo
     */
    status = acpi_evaluate_object(pr->handle, "_SUN", NULL, &buffer);
    if (ACPI_SUCCESS(status))
        arch_fix_phys_package_id(pr->id, object.integer.value);

    return 0;
}

static DEFINE_PER_CPU(void *, processor_device_array);

static void acpi_processor_notify(struct acpi_device *device, u32 event)
{
    struct acpi_processor *pr = acpi_driver_data(device);
    int saved;

    if (!pr)
        return;

    switch (event) {
    case ACPI_PROCESSOR_NOTIFY_PERFORMANCE:
        saved = pr->performance_platform_limit;
        acpi_processor_ppc_has_changed(pr, 1);
        if (saved == pr->performance_platform_limit)
            break;
        acpi_bus_generate_proc_event(device, event,
                    pr->performance_platform_limit);
        acpi_bus_generate_netlink_event(device->pnp.device_class,
                          dev_name(&device->dev), event,
                          pr->performance_platform_limit);
        break;
    case ACPI_PROCESSOR_NOTIFY_POWER:
        acpi_processor_cst_has_changed(pr);
        acpi_bus_generate_proc_event(device, event, 0);
        acpi_bus_generate_netlink_event(device->pnp.device_class,
                          dev_name(&device->dev), event, 0);
        break;
    case ACPI_PROCESSOR_NOTIFY_THROTTLING:
        acpi_processor_tstate_has_changed(pr);
        acpi_bus_generate_proc_event(device, event, 0);
        acpi_bus_generate_netlink_event(device->pnp.device_class,
                          dev_name(&device->dev), event, 0);
        break;
    default:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Unsupported event [0x%x]\n", event));
        break;
    }

    return;
}

static int acpi_cpu_soft_notify(struct notifier_block *nfb,
        unsigned long action, void *hcpu)
{
    unsigned int cpu = (unsigned long)hcpu;
    struct acpi_processor *pr = per_cpu(processors, cpu);

    if (action == CPU_ONLINE && pr) {
        /* CPU got physically hotplugged and onlined the first time:
         * Initialize missing things
         */
        if (pr->flags.need_hotplug_init) {
            printk(KERN_INFO "Will online and init hotplugged "
                   "CPU: %d\n", pr->id);
            WARN(acpi_processor_start(pr), "Failed to start CPU:"
                " %d\n", pr->id);
            pr->flags.need_hotplug_init = 0;
        /* Normal CPU soft online event */
        } else {
            acpi_processor_ppc_has_changed(pr, 0);
            acpi_processor_hotplug(pr);
            acpi_processor_reevaluate_tstate(pr, action);
            acpi_processor_tstate_has_changed(pr);
        }
    }
    if (action == CPU_DEAD && pr) {
        /* invalidate the flag.throttling after one CPU is offline */
        acpi_processor_reevaluate_tstate(pr, action);
    }
    return NOTIFY_OK;
}

static struct notifier_block acpi_cpu_notifier =
{
        .notifier_call = acpi_cpu_soft_notify,
};

/*
 * acpi_processor_start() is called by the cpu_hotplug_notifier func:
 * acpi_cpu_soft_notify(). Getting it __cpuinit{data} is difficult, the
 * root cause seem to be that acpi_processor_uninstall_hotplug_notify()
 * is in the module_exit (__exit) func. Allowing acpi_processor_start()
 * to not be in __cpuinit section, but being called from __cpuinit funcs
 * via __ref looks like the right thing to do here.
 */
static __ref int acpi_processor_start(struct acpi_processor *pr)
{
    struct acpi_device *device = per_cpu(processor_device_array, pr->id);
    int result = 0;

#ifdef CONFIG_CPU_FREQ
    acpi_processor_ppc_has_changed(pr, 0);
    acpi_processor_load_module(pr);
#endif
    acpi_processor_get_throttling_info(pr);
    acpi_processor_get_limit_info(pr);

    if (!cpuidle_get_driver() || cpuidle_get_driver() == &acpi_idle_driver)
        acpi_processor_power_init(pr);

    pr->cdev = thermal_cooling_device_register("Processor", device,
                           &processor_cooling_ops);
    if (IS_ERR(pr->cdev)) {
        result = PTR_ERR(pr->cdev);
        goto err_power_exit;
    }

    dev_dbg(&device->dev, "registered as cooling_device%d\n",
        pr->cdev->id);

    result = sysfs_create_link(&device->dev.kobj,
                   &pr->cdev->device.kobj,
                   "thermal_cooling");
    if (result) {
        printk(KERN_ERR PREFIX "Create sysfs link\n");
        goto err_thermal_unregister;
    }
    result = sysfs_create_link(&pr->cdev->device.kobj,
                   &device->dev.kobj,
                   "device");
    if (result) {
        printk(KERN_ERR PREFIX "Create sysfs link\n");
        goto err_remove_sysfs_thermal;
    }

    return 0;

err_remove_sysfs_thermal:
    sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
err_thermal_unregister:
    thermal_cooling_device_unregister(pr->cdev);
err_power_exit:
    acpi_processor_power_exit(pr);

    return result;
}

/*
 * Do not put anything in here which needs the core to be online.
 * For example MSR access or setting up things which check for cpuinfo_x86
 * (cpu_data(cpu)) values, like CPU feature flags, family, model, etc.
 * Such things have to be put in and set up above in acpi_processor_start()
 */
static int __cpuinit acpi_processor_add(struct acpi_device *device)
{
    struct acpi_processor *pr = NULL;
    int result = 0;
    struct device *dev;

    pr = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
    if (!pr)
        return -ENOMEM;

    if (!zalloc_cpumask_var(&pr->throttling.shared_cpu_map, GFP_KERNEL)) {
        result = -ENOMEM;
        goto err_free_pr;
    }

    pr->handle = device->handle;
    strcpy(acpi_device_name(device), ACPI_PROCESSOR_DEVICE_NAME);
    strcpy(acpi_device_class(device), ACPI_PROCESSOR_CLASS);
    device->driver_data = pr;

    result = acpi_processor_get_info(device);
    if (result) {
        /* Processor is physically not present */
        return 0;
    }

#ifdef CONFIG_SMP
    if (pr->id >= setup_max_cpus && pr->id != 0)
        return 0;
#endif

    BUG_ON((pr->id >= nr_cpu_ids) || (pr->id < 0));

    /*
     * Buggy BIOS check
     * ACPI id of processors can be reported wrongly by the BIOS.
     * Don't trust it blindly
     */
    if (per_cpu(processor_device_array, pr->id) != NULL &&
        per_cpu(processor_device_array, pr->id) != device) {
        printk(KERN_WARNING "BIOS reported wrong ACPI id "
            "for the processor\n");
        result = -ENODEV;
        goto err_free_cpumask;
    }
    per_cpu(processor_device_array, pr->id) = device;

    per_cpu(processors, pr->id) = pr;

    dev = get_cpu_device(pr->id);
    if (sysfs_create_link(&device->dev.kobj, &dev->kobj, "sysdev")) {
        result = -EFAULT;
        goto err_clear_processor;
    }

    /*
     * Do not start hotplugged CPUs now, but when they
     * are onlined the first time
     */
    if (pr->flags.need_hotplug_init)
        return 0;

    result = acpi_processor_start(pr);
    if (result)
        goto err_remove_sysfs;

    return 0;

err_remove_sysfs:
    sysfs_remove_link(&device->dev.kobj, "sysdev");
err_clear_processor:
    /*
     * processor_device_array is not cleared to allow checks for buggy BIOS
     */ 
    per_cpu(processors, pr->id) = NULL;
err_free_cpumask:
    free_cpumask_var(pr->throttling.shared_cpu_map);
err_free_pr:
    kfree(pr);
    return result;
}

static int acpi_processor_remove(struct acpi_device *device, int type)
{
    struct acpi_processor *pr = NULL;


    if (!device || !acpi_driver_data(device))
        return -EINVAL;

    pr = acpi_driver_data(device);

    if (pr->id >= nr_cpu_ids)
        goto free;

    if (type == ACPI_BUS_REMOVAL_EJECT) {
        if (acpi_processor_handle_eject(pr))
            return -EINVAL;
    }

    acpi_processor_power_exit(pr);

    sysfs_remove_link(&device->dev.kobj, "sysdev");

    if (pr->cdev) {
        sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
        sysfs_remove_link(&pr->cdev->device.kobj, "device");
        thermal_cooling_device_unregister(pr->cdev);
        pr->cdev = NULL;
    }

    per_cpu(processors, pr->id) = NULL;
    per_cpu(processor_device_array, pr->id) = NULL;

free:
    free_cpumask_var(pr->throttling.shared_cpu_map);
    kfree(pr);

    return 0;
}

#ifdef CONFIG_ACPI_HOTPLUG_CPU
/****************************************************************************
 *  Acpi processor hotplug support                          *
 ****************************************************************************/

static int is_processor_present(acpi_handle handle)
{
    acpi_status status;
    unsigned long long sta = 0;


    status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);

    if (ACPI_SUCCESS(status) && (sta & ACPI_STA_DEVICE_PRESENT))
        return 1;

    /*
     * _STA is mandatory for a processor that supports hot plug
     */
    if (status == AE_NOT_FOUND)
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                "Processor does not support hot plug\n"));
    else
        ACPI_EXCEPTION((AE_INFO, status,
                "Processor Device is not present"));
    return 0;
}

static
int acpi_processor_device_add(acpi_handle handle, struct acpi_device **device)
{
    acpi_handle phandle;
    struct acpi_device *pdev;


    if (acpi_get_parent(handle, &phandle)) {
        return -ENODEV;
    }

    if (acpi_bus_get_device(phandle, &pdev)) {
        return -ENODEV;
    }

    if (acpi_bus_add(device, pdev, handle, ACPI_BUS_TYPE_PROCESSOR)) {
        return -ENODEV;
    }

    return 0;
}

static void acpi_processor_hotplug_notify(acpi_handle handle,
                      u32 event, void *data)
{
    struct acpi_processor *pr;
    struct acpi_device *device = NULL;
    u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
    int result;

    switch (event) {
    case ACPI_NOTIFY_BUS_CHECK:
    case ACPI_NOTIFY_DEVICE_CHECK:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
        "Processor driver received %s event\n",
               (event == ACPI_NOTIFY_BUS_CHECK) ?
               "ACPI_NOTIFY_BUS_CHECK" : "ACPI_NOTIFY_DEVICE_CHECK"));

        if (!is_processor_present(handle))
            break;

        if (!acpi_bus_get_device(handle, &device))
            break;

        result = acpi_processor_device_add(handle, &device);
        if (result) {
            printk(KERN_ERR PREFIX "Unable to add the device\n");
            break;
        }

        ost_code = ACPI_OST_SC_SUCCESS;
        break;

    case ACPI_NOTIFY_EJECT_REQUEST:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "received ACPI_NOTIFY_EJECT_REQUEST\n"));

        if (acpi_bus_get_device(handle, &device)) {
            printk(KERN_ERR PREFIX
                    "Device don't exist, dropping EJECT\n");
            break;
        }
        pr = acpi_driver_data(device);
        if (!pr) {
            printk(KERN_ERR PREFIX
                    "Driver data is NULL, dropping EJECT\n");
            break;
        }

        /* REVISIT: update when eject is supported */
        ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
        break;

    default:
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Unsupported event [0x%x]\n", event));

        /* non-hotplug event; possibly handled by other handler */
        return;
    }

    /* Inform firmware that the hotplug operation has completed */
    (void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
    return;
}

static acpi_status is_processor_device(acpi_handle handle)
{
    struct acpi_device_info *info;
    char *hid;
    acpi_status status;

    status = acpi_get_object_info(handle, &info);
    if (ACPI_FAILURE(status))
        return status;

    if (info->type == ACPI_TYPE_PROCESSOR) {
        kfree(info);
        return AE_OK;   /* found a processor object */
    }

    if (!(info->valid & ACPI_VALID_HID)) {
        kfree(info);
        return AE_ERROR;
    }

    hid = info->hardware_id.string;
    if ((hid == NULL) || strcmp(hid, ACPI_PROCESSOR_DEVICE_HID)) {
        kfree(info);
        return AE_ERROR;
    }

    kfree(info);
    return AE_OK;   /* found a processor device object */
}

static acpi_status
processor_walk_namespace_cb(acpi_handle handle,
                u32 lvl, void *context, void **rv)
{
    acpi_status status;
    int *action = context;

    status = is_processor_device(handle);
    if (ACPI_FAILURE(status))
        return AE_OK;   /* not a processor; continue to walk */

    switch (*action) {
    case INSTALL_NOTIFY_HANDLER:
        acpi_install_notify_handler(handle,
                        ACPI_SYSTEM_NOTIFY,
                        acpi_processor_hotplug_notify,
                        NULL);
        break;
    case UNINSTALL_NOTIFY_HANDLER:
        acpi_remove_notify_handler(handle,
                       ACPI_SYSTEM_NOTIFY,
                       acpi_processor_hotplug_notify);
        break;
    default:
        break;
    }

    /* found a processor; skip walking underneath */
    return AE_CTRL_DEPTH;
}

static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
{
    acpi_handle handle = pr->handle;

    if (!is_processor_present(handle)) {
        return AE_ERROR;
    }

    if (acpi_map_lsapic(handle, &pr->id))
        return AE_ERROR;

    if (arch_register_cpu(pr->id)) {
        acpi_unmap_lsapic(pr->id);
        return AE_ERROR;
    }

    /* CPU got hot-plugged, but cpu_data is not initialized yet
     * Set flag to delay cpu_idle/throttling initialization
     * in:
     * acpi_processor_add()
     *   acpi_processor_get_info()
     * and do it when the CPU gets online the first time
     * TBD: Cleanup above functions and try to do this more elegant.
     */
    printk(KERN_INFO "CPU %d got hotplugged\n", pr->id);
    pr->flags.need_hotplug_init = 1;

    return AE_OK;
}

static int acpi_processor_handle_eject(struct acpi_processor *pr)
{
    if (cpu_online(pr->id))
        cpu_down(pr->id);

    arch_unregister_cpu(pr->id);
    acpi_unmap_lsapic(pr->id);
    return (0);
}
#else
static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
{
    return AE_ERROR;
}
static int acpi_processor_handle_eject(struct acpi_processor *pr)
{
    return (-EINVAL);
}
#endif

static
void acpi_processor_install_hotplug_notify(void)
{
#ifdef CONFIG_ACPI_HOTPLUG_CPU
    int action = INSTALL_NOTIFY_HANDLER;
    acpi_walk_namespace(ACPI_TYPE_ANY,
                ACPI_ROOT_OBJECT,
                ACPI_UINT32_MAX,
                processor_walk_namespace_cb, NULL, &action, NULL);
#endif
    register_hotcpu_notifier(&acpi_cpu_notifier);
}

static
void acpi_processor_uninstall_hotplug_notify(void)
{
#ifdef CONFIG_ACPI_HOTPLUG_CPU
    int action = UNINSTALL_NOTIFY_HANDLER;
    acpi_walk_namespace(ACPI_TYPE_ANY,
                ACPI_ROOT_OBJECT,
                ACPI_UINT32_MAX,
                processor_walk_namespace_cb, NULL, &action, NULL);
#endif
    unregister_hotcpu_notifier(&acpi_cpu_notifier);
}

/*
 * We keep the driver loaded even when ACPI is not running.
 * This is needed for the powernow-k8 driver, that works even without
 * ACPI, but needs symbols from this driver
 */

static int __init acpi_processor_init(void)
{
    int result = 0;

    if (acpi_disabled)
        return 0;

    result = acpi_bus_register_driver(&acpi_processor_driver);
    if (result < 0)
        return result;

    acpi_processor_install_hotplug_notify();

    acpi_thermal_cpufreq_init();

    acpi_processor_ppc_init();

    acpi_processor_throttling_init();

    return 0;
}

static void __exit acpi_processor_exit(void)
{
    if (acpi_disabled)
        return;

    acpi_processor_ppc_exit();

    acpi_thermal_cpufreq_exit();

    acpi_processor_uninstall_hotplug_notify();

    acpi_bus_unregister_driver(&acpi_processor_driver);

    return;
}

module_init(acpi_processor_init);
module_exit(acpi_processor_exit);

MODULE_ALIAS("processor");