/*
 * scan.c - support for transforming the ACPI namespace into individual objects
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/signal.h>
#include <linux/kthread.h>
#include <linux/dmi.h>
#include <linux/nls.h>

#include <acpi/acpi_drivers.h>

#include "internal.h"

#define _COMPONENT              ACPI_BUS_COMPONENT
ACPI_MODULE_NAME("scan");
#define STRUCT_TO_INT(s)        (*((int*)&s))
extern struct acpi_device *acpi_root;

#define ACPI_BUS_CLASS                  "system_bus"
#define ACPI_BUS_HID                    "LNXSYBUS"
#define ACPI_BUS_DEVICE_NAME            "System Bus"

#define ACPI_IS_ROOT_DEVICE(device)    (!(device)->parent)

static const char *dummy_hid = "device";

/*
 * The following ACPI IDs are known to be suitable for representing as
 * platform devices.
 */
static const struct acpi_device_id acpi_platform_device_ids[] = {

        { "PNP0D40" },

        /* Haswell LPSS devices */
        { "INT33C0", 0 },
        { "INT33C1", 0 },
        { "INT33C2", 0 },
        { "INT33C3", 0 },
        { "INT33C4", 0 },
        { "INT33C5", 0 },
        { "INT33C6", 0 },
        { "INT33C7", 0 },

        { }
};

static LIST_HEAD(acpi_device_list);
static LIST_HEAD(acpi_bus_id_list);
DEFINE_MUTEX(acpi_device_lock);
LIST_HEAD(acpi_wakeup_device_list);

struct acpi_device_bus_id{
        char bus_id[15];
        unsigned int instance_no;
        struct list_head node;
};

/*
 * Creates hid/cid(s) string needed for modalias and uevent
 * e.g. on a device with hid:IBM0001 and cid:ACPI0001 you get:
 * char *modalias: "acpi:IBM0001:ACPI0001"
*/
static int create_modalias(struct acpi_device *acpi_dev, char *modalias,
                           int size)
{
        int len;
        int count;
        struct acpi_hardware_id *id;

        if (list_empty(&acpi_dev->pnp.ids))
                return 0;

        len = snprintf(modalias, size, "acpi:");
        size -= len;

        list_for_each_entry(id, &acpi_dev->pnp.ids, list) {
                count = snprintf(&modalias[len], size, "%s:", id->id);
                if (count < 0 || count >= size)
                        return -EINVAL;
                len += count;
                size -= count;
        }

        modalias[len] = '\0';
        return len;
}

static ssize_t
acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        int len;

        /* Device has no HID and no CID or string is >1024 */
        len = create_modalias(acpi_dev, buf, 1024);
        if (len <= 0)
                return 0;
        buf[len++] = '\n';
        return len;
}
static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);

/**
 * acpi_bus_hot_remove_device: hot-remove a device and its children
 * @context: struct acpi_eject_event pointer (freed in this func)
 *
 * Hot-remove a device and its children. This function frees up the
 * memory space passed by arg context, so that the caller may call
 * this function asynchronously through acpi_os_hotplug_execute().
 */
void acpi_bus_hot_remove_device(void *context)
{
        struct acpi_eject_event *ej_event = (struct acpi_eject_event *) context;
        struct acpi_device *device;
        acpi_handle handle = ej_event->handle;
        acpi_handle temp;
        struct acpi_object_list arg_list;
        union acpi_object arg;
        acpi_status status = AE_OK;
        u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */

        if (acpi_bus_get_device(handle, &device))
                goto err_out;

        if (!device)
                goto err_out;

        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                "Hot-removing device %s...\n", dev_name(&device->dev)));

        if (acpi_bus_trim(device, 1)) {
                printk(KERN_ERR PREFIX
                                "Removing device failed\n");
                goto err_out;
        }

        /* device has been freed */
        device = NULL;

        /* power off device */
        status = acpi_evaluate_object(handle, "_PS3", NULL, NULL);
        if (ACPI_FAILURE(status) && status != AE_NOT_FOUND)
                printk(KERN_WARNING PREFIX
                                "Power-off device failed\n");

        if (ACPI_SUCCESS(acpi_get_handle(handle, "_LCK", &temp))) {
                arg_list.count = 1;
                arg_list.pointer = &arg;
                arg.type = ACPI_TYPE_INTEGER;
                arg.integer.value = 0;
                acpi_evaluate_object(handle, "_LCK", &arg_list, NULL);
        }

        arg_list.count = 1;
        arg_list.pointer = &arg;
        arg.type = ACPI_TYPE_INTEGER;
        arg.integer.value = 1;

        /*
         * TBD: _EJD support.
         */
        status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL);
        if (ACPI_FAILURE(status)) {
                if (status != AE_NOT_FOUND)
                        printk(KERN_WARNING PREFIX
                                        "Eject device failed\n");
                goto err_out;
        }

        kfree(context);
        return;

err_out:
        /* Inform firmware the hot-remove operation has completed w/ error */
        (void) acpi_evaluate_hotplug_ost(handle,
                                ej_event->event, ost_code, NULL);
        kfree(context);
        return;
}
EXPORT_SYMBOL(acpi_bus_hot_remove_device);

static ssize_t
acpi_eject_store(struct device *d, struct device_attribute *attr,
                const char *buf, size_t count)
{
        int ret = count;
        acpi_status status;
        acpi_object_type type = 0;
        struct acpi_device *acpi_device = to_acpi_device(d);
        struct acpi_eject_event *ej_event;

        if ((!count) || (buf[0] != '1')) {
                return -EINVAL;
        }
#ifndef FORCE_EJECT
        if (acpi_device->driver == NULL) {
                ret = -ENODEV;
                goto err;
        }
#endif
        status = acpi_get_type(acpi_device->handle, &type);
        if (ACPI_FAILURE(status) || (!acpi_device->flags.ejectable)) {
                ret = -ENODEV;
                goto err;
        }

        ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
        if (!ej_event) {
                ret = -ENOMEM;
                goto err;
        }

        ej_event->handle = acpi_device->handle;
        if (acpi_device->flags.eject_pending) {
                /* event originated from ACPI eject notification */
                ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
                acpi_device->flags.eject_pending = 0;
        } else {
                /* event originated from user */
                ej_event->event = ACPI_OST_EC_OSPM_EJECT;
                (void) acpi_evaluate_hotplug_ost(ej_event->handle,
                        ej_event->event, ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
        }

        acpi_os_hotplug_execute(acpi_bus_hot_remove_device, (void *)ej_event);
err:
        return ret;
}

static DEVICE_ATTR(eject, 0200, NULL, acpi_eject_store);

static ssize_t
acpi_device_hid_show(struct device *dev, struct device_attribute *attr, char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        return sprintf(buf, "%s\n", acpi_device_hid(acpi_dev));
}
static DEVICE_ATTR(hid, 0444, acpi_device_hid_show, NULL);

static ssize_t acpi_device_uid_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        return sprintf(buf, "%s\n", acpi_dev->pnp.unique_id);
}
static DEVICE_ATTR(uid, 0444, acpi_device_uid_show, NULL);

static ssize_t acpi_device_adr_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        return sprintf(buf, "0x%08x\n",
                       (unsigned int)(acpi_dev->pnp.bus_address));
}
static DEVICE_ATTR(adr, 0444, acpi_device_adr_show, NULL);

static ssize_t
acpi_device_path_show(struct device *dev, struct device_attribute *attr, char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        struct acpi_buffer path = {ACPI_ALLOCATE_BUFFER, NULL};
        int result;

        result = acpi_get_name(acpi_dev->handle, ACPI_FULL_PATHNAME, &path);
        if (result)
                goto end;

        result = sprintf(buf, "%s\n", (char*)path.pointer);
        kfree(path.pointer);
end:
        return result;
}
static DEVICE_ATTR(path, 0444, acpi_device_path_show, NULL);

/* sysfs file that shows description text from the ACPI _STR method */
static ssize_t description_show(struct device *dev,
                                struct device_attribute *attr,
                                char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        int result;

        if (acpi_dev->pnp.str_obj == NULL)
                return 0;

        /*
         * The _STR object contains a Unicode identifier for a device.
         * We need to convert to utf-8 so it can be displayed.
         */
        result = utf16s_to_utf8s(
                (wchar_t *)acpi_dev->pnp.str_obj->buffer.pointer,
                acpi_dev->pnp.str_obj->buffer.length,
                UTF16_LITTLE_ENDIAN, buf,
                PAGE_SIZE);

        buf[result++] = '\n';

        return result;
}
static DEVICE_ATTR(description, 0444, description_show, NULL);

static ssize_t
acpi_device_sun_show(struct device *dev, struct device_attribute *attr,
                     char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        return sprintf(buf, "%lu\n", acpi_dev->pnp.sun);
}
static DEVICE_ATTR(sun, 0444, acpi_device_sun_show, NULL);

static int acpi_device_setup_files(struct acpi_device *dev)
{
        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
        acpi_status status;
        acpi_handle temp;
        unsigned long long sun;
        int result = 0;

        /*
         * Devices gotten from FADT don't have a "path" attribute
         */
        if (dev->handle) {
                result = device_create_file(&dev->dev, &dev_attr_path);
                if (result)
                        goto end;
        }

        if (!list_empty(&dev->pnp.ids)) {
                result = device_create_file(&dev->dev, &dev_attr_hid);
                if (result)
                        goto end;

                result = device_create_file(&dev->dev, &dev_attr_modalias);
                if (result)
                        goto end;
        }

        /*
         * If device has _STR, 'description' file is created
         */
        status = acpi_get_handle(dev->handle, "_STR", &temp);
        if (ACPI_SUCCESS(status)) {
                status = acpi_evaluate_object(dev->handle, "_STR",
                                        NULL, &buffer);
                if (ACPI_FAILURE(status))
                        buffer.pointer = NULL;
                dev->pnp.str_obj = buffer.pointer;
                result = device_create_file(&dev->dev, &dev_attr_description);
                if (result)
                        goto end;
        }

        if (dev->flags.bus_address)
                result = device_create_file(&dev->dev, &dev_attr_adr);
        if (dev->pnp.unique_id)
                result = device_create_file(&dev->dev, &dev_attr_uid);

        status = acpi_evaluate_integer(dev->handle, "_SUN", NULL, &sun);
        if (ACPI_SUCCESS(status)) {
                dev->pnp.sun = (unsigned long)sun;
                result = device_create_file(&dev->dev, &dev_attr_sun);
                if (result)
                        goto end;
        } else {
                dev->pnp.sun = (unsigned long)-1;
        }

        /*
         * If device has _EJ0, 'eject' file is created that is used to trigger
         * hot-removal function from userland.
         */
        status = acpi_get_handle(dev->handle, "_EJ0", &temp);
        if (ACPI_SUCCESS(status))
                result = device_create_file(&dev->dev, &dev_attr_eject);
end:
        return result;
}

static void acpi_device_remove_files(struct acpi_device *dev)
{
        acpi_status status;
        acpi_handle temp;

        /*
         * If device has _STR, remove 'description' file
         */
        status = acpi_get_handle(dev->handle, "_STR", &temp);
        if (ACPI_SUCCESS(status)) {
                kfree(dev->pnp.str_obj);
                device_remove_file(&dev->dev, &dev_attr_description);
        }
        /*
         * If device has _EJ0, remove 'eject' file.
         */
        status = acpi_get_handle(dev->handle, "_EJ0", &temp);
        if (ACPI_SUCCESS(status))
                device_remove_file(&dev->dev, &dev_attr_eject);

        status = acpi_get_handle(dev->handle, "_SUN", &temp);
        if (ACPI_SUCCESS(status))
                device_remove_file(&dev->dev, &dev_attr_sun);

        if (dev->pnp.unique_id)
                device_remove_file(&dev->dev, &dev_attr_uid);
        if (dev->flags.bus_address)
                device_remove_file(&dev->dev, &dev_attr_adr);
        device_remove_file(&dev->dev, &dev_attr_modalias);
        device_remove_file(&dev->dev, &dev_attr_hid);
        if (dev->handle)
                device_remove_file(&dev->dev, &dev_attr_path);
}
/* --------------------------------------------------------------------------
                        ACPI Bus operations
   -------------------------------------------------------------------------- */

static const struct acpi_device_id *__acpi_match_device(
        struct acpi_device *device, const struct acpi_device_id *ids)
{
        const struct acpi_device_id *id;
        struct acpi_hardware_id *hwid;

        /*
         * If the device is not present, it is unnecessary to load device
         * driver for it.
         */
        if (!device->status.present)
                return NULL;

        for (id = ids; id->id[0]; id++)
                list_for_each_entry(hwid, &device->pnp.ids, list)
                        if (!strcmp((char *) id->id, hwid->id))
                                return id;

        return NULL;
}

/**
 * acpi_match_device - Match a struct device against a given list of ACPI IDs
 * @ids: Array of struct acpi_device_id object to match against.
 * @dev: The device structure to match.
 *
 * Check if @dev has a valid ACPI handle and if there is a struct acpi_device
 * object for that handle and use that object to match against a given list of
 * device IDs.
 *
 * Return a pointer to the first matching ID on success or %NULL on failure.
 */
const struct acpi_device_id *acpi_match_device(const struct acpi_device_id *ids,
                                               const struct device *dev)
{
        struct acpi_device *adev;

        if (!ids || !ACPI_HANDLE(dev)
            || ACPI_FAILURE(acpi_bus_get_device(ACPI_HANDLE(dev), &adev)))
                return NULL;

        return __acpi_match_device(adev, ids);
}
EXPORT_SYMBOL_GPL(acpi_match_device);

int acpi_match_device_ids(struct acpi_device *device,
                          const struct acpi_device_id *ids)
{
        return __acpi_match_device(device, ids) ? 0 : -ENOENT;
}
EXPORT_SYMBOL(acpi_match_device_ids);

static void acpi_free_ids(struct acpi_device *device)
{
        struct acpi_hardware_id *id, *tmp;

        list_for_each_entry_safe(id, tmp, &device->pnp.ids, list) {
                kfree(id->id);
                kfree(id);
        }
}

static void acpi_device_release(struct device *dev)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        acpi_free_ids(acpi_dev);
        kfree(acpi_dev->pnp.unique_id);
        kfree(acpi_dev);
}

static int acpi_bus_match(struct device *dev, struct device_driver *drv)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        struct acpi_driver *acpi_drv = to_acpi_driver(drv);

        return !acpi_match_device_ids(acpi_dev, acpi_drv->ids);
}

static int acpi_device_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        int len;

        if (list_empty(&acpi_dev->pnp.ids))
                return 0;

        if (add_uevent_var(env, "MODALIAS="))
                return -ENOMEM;
        len = create_modalias(acpi_dev, &env->buf[env->buflen - 1],
                              sizeof(env->buf) - env->buflen);
        if (len >= (sizeof(env->buf) - env->buflen))
                return -ENOMEM;
        env->buflen += len;
        return 0;
}

static void acpi_device_notify(acpi_handle handle, u32 event, void *data)
{
        struct acpi_device *device = data;

        device->driver->ops.notify(device, event);
}

static acpi_status acpi_device_notify_fixed(void *data)
{
        struct acpi_device *device = data;

        /* Fixed hardware devices have no handles */
        acpi_device_notify(NULL, ACPI_FIXED_HARDWARE_EVENT, device);
        return AE_OK;
}

static int acpi_device_install_notify_handler(struct acpi_device *device)
{
        acpi_status status;

        if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON)
                status =
                    acpi_install_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
                                                     acpi_device_notify_fixed,
                                                     device);
        else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON)
                status =
                    acpi_install_fixed_event_handler(ACPI_EVENT_SLEEP_BUTTON,
                                                     acpi_device_notify_fixed,
                                                     device);
        else
                status = acpi_install_notify_handler(device->handle,
                                                     ACPI_DEVICE_NOTIFY,
                                                     acpi_device_notify,
                                                     device);

        if (ACPI_FAILURE(status))
                return -EINVAL;
        return 0;
}

static void acpi_device_remove_notify_handler(struct acpi_device *device)
{
        if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON)
                acpi_remove_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
                                                acpi_device_notify_fixed);
        else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON)
                acpi_remove_fixed_event_handler(ACPI_EVENT_SLEEP_BUTTON,
                                                acpi_device_notify_fixed);
        else
                acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
                                           acpi_device_notify);
}

static int acpi_bus_driver_init(struct acpi_device *, struct acpi_driver *);
static int acpi_start_single_object(struct acpi_device *);
static int acpi_device_probe(struct device * dev)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        struct acpi_driver *acpi_drv = to_acpi_driver(dev->driver);
        int ret;

        ret = acpi_bus_driver_init(acpi_dev, acpi_drv);
        if (!ret) {
                if (acpi_dev->bus_ops.acpi_op_start)
                        acpi_start_single_object(acpi_dev);

                if (acpi_drv->ops.notify) {
                        ret = acpi_device_install_notify_handler(acpi_dev);
                        if (ret) {
                                if (acpi_drv->ops.remove)
                                        acpi_drv->ops.remove(acpi_dev,
                                                     acpi_dev->removal_type);
                                return ret;
                        }
                }

                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                        "Found driver [%s] for device [%s]\n",
                        acpi_drv->name, acpi_dev->pnp.bus_id));
                get_device(dev);
        }
        return ret;
}

static int acpi_device_remove(struct device * dev)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        struct acpi_driver *acpi_drv = acpi_dev->driver;

        if (acpi_drv) {
                if (acpi_drv->ops.notify)
                        acpi_device_remove_notify_handler(acpi_dev);
                if (acpi_drv->ops.remove)
                        acpi_drv->ops.remove(acpi_dev, acpi_dev->removal_type);
        }
        acpi_dev->driver = NULL;
        acpi_dev->driver_data = NULL;

        put_device(dev);
        return 0;
}

struct bus_type acpi_bus_type = {
        .name           = "acpi",
        .match          = acpi_bus_match,
        .probe          = acpi_device_probe,
        .remove         = acpi_device_remove,
        .uevent         = acpi_device_uevent,
};

static int acpi_device_register(struct acpi_device *device)
{
        int result;
        struct acpi_device_bus_id *acpi_device_bus_id, *new_bus_id;
        int found = 0;

        /*
         * Linkage
         * -------
         * Link this device to its parent and siblings.
         */
        INIT_LIST_HEAD(&device->children);
        INIT_LIST_HEAD(&device->node);
        INIT_LIST_HEAD(&device->wakeup_list);
        INIT_LIST_HEAD(&device->physical_node_list);
        mutex_init(&device->physical_node_lock);

        new_bus_id = kzalloc(sizeof(struct acpi_device_bus_id), GFP_KERNEL);
        if (!new_bus_id) {
                printk(KERN_ERR PREFIX "Memory allocation error\n");
                return -ENOMEM;
        }

        mutex_lock(&acpi_device_lock);
        /*
         * Find suitable bus_id and instance number in acpi_bus_id_list
         * If failed, create one and link it into acpi_bus_id_list
         */
        list_for_each_entry(acpi_device_bus_id, &acpi_bus_id_list, node) {
                if (!strcmp(acpi_device_bus_id->bus_id,
                            acpi_device_hid(device))) {
                        acpi_device_bus_id->instance_no++;
                        found = 1;
                        kfree(new_bus_id);
                        break;
                }
        }
        if (!found) {
                acpi_device_bus_id = new_bus_id;
                strcpy(acpi_device_bus_id->bus_id, acpi_device_hid(device));
                acpi_device_bus_id->instance_no = 0;
                list_add_tail(&acpi_device_bus_id->node, &acpi_bus_id_list);
        }
        dev_set_name(&device->dev, "%s:%02x", acpi_device_bus_id->bus_id, acpi_device_bus_id->instance_no);

        if (device->parent)
                list_add_tail(&device->node, &device->parent->children);

        if (device->wakeup.flags.valid)
                list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);
        mutex_unlock(&acpi_device_lock);

        if (device->parent)
                device->dev.parent = &device->parent->dev;
        device->dev.bus = &acpi_bus_type;
        device->dev.release = &acpi_device_release;
        result = device_register(&device->dev);
        if (result) {
                dev_err(&device->dev, "Error registering device\n");
                goto end;
        }

        result = acpi_device_setup_files(device);
        if (result)
                printk(KERN_ERR PREFIX "Error creating sysfs interface for device %s\n",
                       dev_name(&device->dev));

        device->removal_type = ACPI_BUS_REMOVAL_NORMAL;
        return 0;
end:
        mutex_lock(&acpi_device_lock);
        if (device->parent)
                list_del(&device->node);
        list_del(&device->wakeup_list);
        mutex_unlock(&acpi_device_lock);
        return result;
}

static void acpi_device_unregister(struct acpi_device *device, int type)
{
        mutex_lock(&acpi_device_lock);
        if (device->parent)
                list_del(&device->node);

        list_del(&device->wakeup_list);
        mutex_unlock(&acpi_device_lock);

        acpi_detach_data(device->handle, acpi_bus_data_handler);

        acpi_device_remove_files(device);
        device_unregister(&device->dev);
}

/* --------------------------------------------------------------------------
                                 Driver Management
   -------------------------------------------------------------------------- */
/**
 * acpi_bus_driver_init - add a device to a driver
 * @device: the device to add and initialize
 * @driver: driver for the device
 *
 * Used to initialize a device via its device driver.  Called whenever a
 * driver is bound to a device.  Invokes the driver's add() ops.
 */
static int
acpi_bus_driver_init(struct acpi_device *device, struct acpi_driver *driver)
{
        int result = 0;

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

        if (!driver->ops.add)
                return -ENOSYS;

        result = driver->ops.add(device);
        if (result) {
                device->driver = NULL;
                device->driver_data = NULL;
                return result;
        }

        device->driver = driver;

        /*
         * TBD - Configuration Management: Assign resources to device based
         * upon possible configuration and currently allocated resources.
         */

        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                          "Driver successfully bound to device\n"));
        return 0;
}

static int acpi_start_single_object(struct acpi_device *device)
{
        int result = 0;
        struct acpi_driver *driver;


        if (!(driver = device->driver))
                return 0;

        if (driver->ops.start) {
                result = driver->ops.start(device);
                if (result && driver->ops.remove)
                        driver->ops.remove(device, ACPI_BUS_REMOVAL_NORMAL);
        }

        return result;
}

/**
 * acpi_bus_register_driver - register a driver with the ACPI bus
 * @driver: driver being registered
 *
 * Registers a driver with the ACPI bus.  Searches the namespace for all
 * devices that match the driver's criteria and binds.  Returns zero for
 * success or a negative error status for failure.
 */
int acpi_bus_register_driver(struct acpi_driver *driver)
{
        int ret;

        if (acpi_disabled)
                return -ENODEV;
        driver->drv.name = driver->name;
        driver->drv.bus = &acpi_bus_type;
        driver->drv.owner = driver->owner;

        ret = driver_register(&driver->drv);
        return ret;
}

EXPORT_SYMBOL(acpi_bus_register_driver);

/**
 * acpi_bus_unregister_driver - unregisters a driver with the APIC bus
 * @driver: driver to unregister
 *
 * Unregisters a driver with the ACPI bus.  Searches the namespace for all
 * devices that match the driver's criteria and unbinds.
 */
void acpi_bus_unregister_driver(struct acpi_driver *driver)
{
        driver_unregister(&driver->drv);
}

EXPORT_SYMBOL(acpi_bus_unregister_driver);

/* --------------------------------------------------------------------------
                                 Device Enumeration
   -------------------------------------------------------------------------- */
static struct acpi_device *acpi_bus_get_parent(acpi_handle handle)
{
        acpi_status status;
        int ret;
        struct acpi_device *device;

        /*
         * Fixed hardware devices do not appear in the namespace and do not
         * have handles, but we fabricate acpi_devices for them, so we have
         * to deal with them specially.
         */
        if (handle == NULL)
                return acpi_root;

        do {
                status = acpi_get_parent(handle, &handle);
                if (status == AE_NULL_ENTRY)
                        return NULL;
                if (ACPI_FAILURE(status))
                        return acpi_root;

                ret = acpi_bus_get_device(handle, &device);
                if (ret == 0)
                        return device;
        } while (1);
}

acpi_status
acpi_bus_get_ejd(acpi_handle handle, acpi_handle *ejd)
{
        acpi_status status;
        acpi_handle tmp;
        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
        union acpi_object *obj;

        status = acpi_get_handle(handle, "_EJD", &tmp);
        if (ACPI_FAILURE(status))
                return status;

        status = acpi_evaluate_object(handle, "_EJD", NULL, &buffer);
        if (ACPI_SUCCESS(status)) {
                obj = buffer.pointer;
                status = acpi_get_handle(ACPI_ROOT_OBJECT, obj->string.pointer,
                                         ejd);
                kfree(buffer.pointer);
        }
        return status;
}
EXPORT_SYMBOL_GPL(acpi_bus_get_ejd);

void acpi_bus_data_handler(acpi_handle handle, void *context)
{

        /* TBD */

        return;
}

static int acpi_bus_get_perf_flags(struct acpi_device *device)
{
        device->performance.state = ACPI_STATE_UNKNOWN;
        return 0;
}

static acpi_status
acpi_bus_extract_wakeup_device_power_package(acpi_handle handle,
                                             struct acpi_device_wakeup *wakeup)
{
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
        union acpi_object *package = NULL;
        union acpi_object *element = NULL;
        acpi_status status;
        int i = 0;

        if (!wakeup)
                return AE_BAD_PARAMETER;

        /* _PRW */
        status = acpi_evaluate_object(handle, "_PRW", NULL, &buffer);
        if (ACPI_FAILURE(status)) {
                ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PRW"));
                return status;
        }

        package = (union acpi_object *)buffer.pointer;

        if (!package || (package->package.count < 2)) {
                status = AE_BAD_DATA;
                goto out;
        }

        element = &(package->package.elements[0]);
        if (!element) {
                status = AE_BAD_DATA;
                goto out;
        }
        if (element->type == ACPI_TYPE_PACKAGE) {
                if ((element->package.count < 2) ||
                    (element->package.elements[0].type !=
                     ACPI_TYPE_LOCAL_REFERENCE)
                    || (element->package.elements[1].type != ACPI_TYPE_INTEGER)) {
                        status = AE_BAD_DATA;
                        goto out;
                }
                wakeup->gpe_device =
                    element->package.elements[0].reference.handle;
                wakeup->gpe_number =
                    (u32) element->package.elements[1].integer.value;
        } else if (element->type == ACPI_TYPE_INTEGER) {
                wakeup->gpe_device = NULL;
                wakeup->gpe_number = element->integer.value;
        } else {
                status = AE_BAD_DATA;
                goto out;
        }

        element = &(package->package.elements[1]);
        if (element->type != ACPI_TYPE_INTEGER) {
                status = AE_BAD_DATA;
                goto out;
        }
        wakeup->sleep_state = element->integer.value;

        if ((package->package.count - 2) > ACPI_MAX_HANDLES) {
                status = AE_NO_MEMORY;
                goto out;
        }
        wakeup->resources.count = package->package.count - 2;
        for (i = 0; i < wakeup->resources.count; i++) {
                element = &(package->package.elements[i + 2]);
                if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
                        status = AE_BAD_DATA;
                        goto out;
                }

                wakeup->resources.handles[i] = element->reference.handle;
        }

        acpi_setup_gpe_for_wake(handle, wakeup->gpe_device, wakeup->gpe_number);

 out:
        kfree(buffer.pointer);

        return status;
}

static void acpi_bus_set_run_wake_flags(struct acpi_device *device)
{
        struct acpi_device_id button_device_ids[] = {
                {"PNP0C0C", 0},
                {"PNP0C0D", 0},
                {"PNP0C0E", 0},
                {"", 0},
        };
        acpi_status status;
        acpi_event_status event_status;

        device->wakeup.flags.notifier_present = 0;

        /* Power button, Lid switch always enable wakeup */
        if (!acpi_match_device_ids(device, button_device_ids)) {
                device->wakeup.flags.run_wake = 1;
                if (!acpi_match_device_ids(device, &button_device_ids[1])) {
                        /* Do not use Lid/sleep button for S5 wakeup */
                        if (device->wakeup.sleep_state == ACPI_STATE_S5)
                                device->wakeup.sleep_state = ACPI_STATE_S4;
                }
                device_set_wakeup_capable(&device->dev, true);
                return;
        }

        status = acpi_get_gpe_status(device->wakeup.gpe_device,
                                        device->wakeup.gpe_number,
                                                &event_status);
        if (status == AE_OK)
                device->wakeup.flags.run_wake =
                                !!(event_status & ACPI_EVENT_FLAG_HANDLE);
}

static void acpi_bus_get_wakeup_device_flags(struct acpi_device *device)
{
        acpi_handle temp;
        acpi_status status = 0;
        int psw_error;

        /* Presence of _PRW indicates wake capable */
        status = acpi_get_handle(device->handle, "_PRW", &temp);
        if (ACPI_FAILURE(status))
                return;

        status = acpi_bus_extract_wakeup_device_power_package(device->handle,
                                                              &device->wakeup);
        if (ACPI_FAILURE(status)) {
                ACPI_EXCEPTION((AE_INFO, status, "Extracting _PRW package"));
                return;
        }

        device->wakeup.flags.valid = 1;
        device->wakeup.prepare_count = 0;
        acpi_bus_set_run_wake_flags(device);
        /* Call _PSW/_DSW object to disable its ability to wake the sleeping
         * system for the ACPI device with the _PRW object.
         * The _PSW object is depreciated in ACPI 3.0 and is replaced by _DSW.
         * So it is necessary to call _DSW object first. Only when it is not
         * present will the _PSW object used.
         */
        psw_error = acpi_device_sleep_wake(device, 0, 0, 0);
        if (psw_error)
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                "error in _DSW or _PSW evaluation\n"));
}

static void acpi_bus_add_power_resource(acpi_handle handle);

static int acpi_bus_get_power_flags(struct acpi_device *device)
{
        acpi_status status = 0;
        acpi_handle handle = NULL;
        u32 i = 0;


        /*
         * Power Management Flags
         */
        status = acpi_get_handle(device->handle, "_PSC", &handle);
        if (ACPI_SUCCESS(status))
                device->power.flags.explicit_get = 1;
        status = acpi_get_handle(device->handle, "_IRC", &handle);
        if (ACPI_SUCCESS(status))
                device->power.flags.inrush_current = 1;

        /*
         * Enumerate supported power management states
         */
        for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++) {
                struct acpi_device_power_state *ps = &device->power.states[i];
                char object_name[5] = { '_', 'P', 'R', '0' + i, '\0' };

                /* Evaluate "_PRx" to se if power resources are referenced */
                acpi_evaluate_reference(device->handle, object_name, NULL,
                                        &ps->resources);
                if (ps->resources.count) {
                        int j;

                        device->power.flags.power_resources = 1;
                        for (j = 0; j < ps->resources.count; j++)
                                acpi_bus_add_power_resource(ps->resources.handles[j]);
                }

                /* Evaluate "_PSx" to see if we can do explicit sets */
                object_name[2] = 'S';
                status = acpi_get_handle(device->handle, object_name, &handle);
                if (ACPI_SUCCESS(status))
                        ps->flags.explicit_set = 1;

                /*
                 * State is valid if there are means to put the device into it.
                 * D3hot is only valid if _PR3 present.
                 */
                if (ps->resources.count ||
                    (ps->flags.explicit_set && i < ACPI_STATE_D3_HOT)) {
                        ps->flags.valid = 1;
                        ps->flags.os_accessible = 1;
                }

                ps->power = -1; /* Unknown - driver assigned */
                ps->latency = -1;       /* Unknown - driver assigned */
        }

        /* Set defaults for D0 and D3 states (always valid) */
        device->power.states[ACPI_STATE_D0].flags.valid = 1;
        device->power.states[ACPI_STATE_D0].power = 100;
        device->power.states[ACPI_STATE_D3].flags.valid = 1;
        device->power.states[ACPI_STATE_D3].power = 0;

        /* Set D3cold's explicit_set flag if _PS3 exists. */
        if (device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set)
                device->power.states[ACPI_STATE_D3_COLD].flags.explicit_set = 1;

        /* Presence of _PS3 or _PRx means we can put the device into D3 cold */
        if (device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set ||
                        device->power.flags.power_resources)
                device->power.states[ACPI_STATE_D3_COLD].flags.os_accessible = 1;

        acpi_bus_init_power(device);

        return 0;
}

static int acpi_bus_get_flags(struct acpi_device *device)
{
        acpi_status status = AE_OK;
        acpi_handle temp = NULL;


        /* Presence of _STA indicates 'dynamic_status' */
        status = acpi_get_handle(device->handle, "_STA", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.dynamic_status = 1;

        /* Presence of _RMV indicates 'removable' */
        status = acpi_get_handle(device->handle, "_RMV", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.removable = 1;

        /* Presence of _EJD|_EJ0 indicates 'ejectable' */
        status = acpi_get_handle(device->handle, "_EJD", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.ejectable = 1;
        else {
                status = acpi_get_handle(device->handle, "_EJ0", &temp);
                if (ACPI_SUCCESS(status))
                        device->flags.ejectable = 1;
        }

        /* Power resources cannot be power manageable. */
        if (device->device_type == ACPI_BUS_TYPE_POWER)
                return 0;

        /* Presence of _PS0|_PR0 indicates 'power manageable' */
        status = acpi_get_handle(device->handle, "_PS0", &temp);
        if (ACPI_FAILURE(status))
                status = acpi_get_handle(device->handle, "_PR0", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.power_manageable = 1;

        /* TBD: Performance management */

        return 0;
}

static void acpi_device_get_busid(struct acpi_device *device)
{
        char bus_id[5] = { '?', 0 };
        struct acpi_buffer buffer = { sizeof(bus_id), bus_id };
        int i = 0;

        /*
         * Bus ID
         * ------
         * The device's Bus ID is simply the object name.
         * TBD: Shouldn't this value be unique (within the ACPI namespace)?
         */
        if (ACPI_IS_ROOT_DEVICE(device)) {
                strcpy(device->pnp.bus_id, "ACPI");
                return;
        }

        switch (device->device_type) {
        case ACPI_BUS_TYPE_POWER_BUTTON:
                strcpy(device->pnp.bus_id, "PWRF");
                break;
        case ACPI_BUS_TYPE_SLEEP_BUTTON:
                strcpy(device->pnp.bus_id, "SLPF");
                break;
        default:
                acpi_get_name(device->handle, ACPI_SINGLE_NAME, &buffer);
                /* Clean up trailing underscores (if any) */
                for (i = 3; i > 1; i--) {
                        if (bus_id[i] == '_')
                                bus_id[i] = '\0';
                        else
                                break;
                }
                strcpy(device->pnp.bus_id, bus_id);
                break;
        }
}

/*
 * acpi_bay_match - see if a device is an ejectable driver bay
 *
 * If an acpi object is ejectable and has one of the ACPI ATA methods defined,
 * then we can safely call it an ejectable drive bay
 */
static int acpi_bay_match(struct acpi_device *device){
        acpi_status status;
        acpi_handle handle;
        acpi_handle tmp;
        acpi_handle phandle;

        handle = device->handle;

        status = acpi_get_handle(handle, "_EJ0", &tmp);
        if (ACPI_FAILURE(status))
                return -ENODEV;

        if ((ACPI_SUCCESS(acpi_get_handle(handle, "_GTF", &tmp))) ||
                (ACPI_SUCCESS(acpi_get_handle(handle, "_GTM", &tmp))) ||
                (ACPI_SUCCESS(acpi_get_handle(handle, "_STM", &tmp))) ||
                (ACPI_SUCCESS(acpi_get_handle(handle, "_SDD", &tmp))))
                return 0;

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

        if ((ACPI_SUCCESS(acpi_get_handle(phandle, "_GTF", &tmp))) ||
                (ACPI_SUCCESS(acpi_get_handle(phandle, "_GTM", &tmp))) ||
                (ACPI_SUCCESS(acpi_get_handle(phandle, "_STM", &tmp))) ||
                (ACPI_SUCCESS(acpi_get_handle(phandle, "_SDD", &tmp))))
                return 0;

        return -ENODEV;
}

/*
 * acpi_dock_match - see if a device has a _DCK method
 */
static int acpi_dock_match(struct acpi_device *device)
{
        acpi_handle tmp;
        return acpi_get_handle(device->handle, "_DCK", &tmp);
}

const char *acpi_device_hid(struct acpi_device *device)
{
        struct acpi_hardware_id *hid;

        if (list_empty(&device->pnp.ids))
                return dummy_hid;

        hid = list_first_entry(&device->pnp.ids, struct acpi_hardware_id, list);
        return hid->id;
}
EXPORT_SYMBOL(acpi_device_hid);

static void acpi_add_id(struct acpi_device *device, const char *dev_id)
{
        struct acpi_hardware_id *id;

        id = kmalloc(sizeof(*id), GFP_KERNEL);
        if (!id)
                return;

        id->id = kstrdup(dev_id, GFP_KERNEL);
        if (!id->id) {
                kfree(id);
                return;
        }

        list_add_tail(&id->list, &device->pnp.ids);
}

/*
 * Old IBM workstations have a DSDT bug wherein the SMBus object
 * lacks the SMBUS01 HID and the methods do not have the necessary "_"
 * prefix.  Work around this.
 */
static int acpi_ibm_smbus_match(struct acpi_device *device)
{
        acpi_handle h_dummy;
        struct acpi_buffer path = {ACPI_ALLOCATE_BUFFER, NULL};
        int result;

        if (!dmi_name_in_vendors("IBM"))
                return -ENODEV;

        /* Look for SMBS object */
        result = acpi_get_name(device->handle, ACPI_SINGLE_NAME, &path);
        if (result)
                return result;

        if (strcmp("SMBS", path.pointer)) {
                result = -ENODEV;
                goto out;
        }

        /* Does it have the necessary (but misnamed) methods? */
        result = -ENODEV;
        if (ACPI_SUCCESS(acpi_get_handle(device->handle, "SBI", &h_dummy)) &&
            ACPI_SUCCESS(acpi_get_handle(device->handle, "SBR", &h_dummy)) &&
            ACPI_SUCCESS(acpi_get_handle(device->handle, "SBW", &h_dummy)))
                result = 0;
out:
        kfree(path.pointer);
        return result;
}

static void acpi_device_set_id(struct acpi_device *device)
{
        acpi_status status;
        struct acpi_device_info *info;
        struct acpi_pnp_device_id_list *cid_list;
        int i;

        switch (device->device_type) {
        case ACPI_BUS_TYPE_DEVICE:
                if (ACPI_IS_ROOT_DEVICE(device)) {
                        acpi_add_id(device, ACPI_SYSTEM_HID);
                        break;
                }

                status = acpi_get_object_info(device->handle, &info);
                if (ACPI_FAILURE(status)) {
                        printk(KERN_ERR PREFIX "%s: Error reading device info\n", __func__);
                        return;
                }

                if (info->valid & ACPI_VALID_HID)
                        acpi_add_id(device, info->hardware_id.string);
                if (info->valid & ACPI_VALID_CID) {
                        cid_list = &info->compatible_id_list;
                        for (i = 0; i < cid_list->count; i++)
                                acpi_add_id(device, cid_list->ids[i].string);
                }
                if (info->valid & ACPI_VALID_ADR) {
                        device->pnp.bus_address = info->address;
                        device->flags.bus_address = 1;
                }
                if (info->valid & ACPI_VALID_UID)
                        device->pnp.unique_id = kstrdup(info->unique_id.string,
                                                        GFP_KERNEL);

                kfree(info);

                /*
                 * Some devices don't reliably have _HIDs & _CIDs, so add
                 * synthetic HIDs to make sure drivers can find them.
                 */
                if (acpi_is_video_device(device))
                        acpi_add_id(device, ACPI_VIDEO_HID);
                else if (ACPI_SUCCESS(acpi_bay_match(device)))
                        acpi_add_id(device, ACPI_BAY_HID);
                else if (ACPI_SUCCESS(acpi_dock_match(device)))
                        acpi_add_id(device, ACPI_DOCK_HID);
                else if (!acpi_ibm_smbus_match(device))
                        acpi_add_id(device, ACPI_SMBUS_IBM_HID);
                else if (list_empty(&device->pnp.ids) &&
                         ACPI_IS_ROOT_DEVICE(device->parent)) {
                        acpi_add_id(device, ACPI_BUS_HID); /* \_SB, LNXSYBUS */
                        strcpy(device->pnp.device_name, ACPI_BUS_DEVICE_NAME);
                        strcpy(device->pnp.device_class, ACPI_BUS_CLASS);
                }

                break;
        case ACPI_BUS_TYPE_POWER:
                acpi_add_id(device, ACPI_POWER_HID);
                break;
        case ACPI_BUS_TYPE_PROCESSOR:
                acpi_add_id(device, ACPI_PROCESSOR_OBJECT_HID);
                break;
        case ACPI_BUS_TYPE_THERMAL:
                acpi_add_id(device, ACPI_THERMAL_HID);
                break;
        case ACPI_BUS_TYPE_POWER_BUTTON:
                acpi_add_id(device, ACPI_BUTTON_HID_POWERF);
                break;
        case ACPI_BUS_TYPE_SLEEP_BUTTON:
                acpi_add_id(device, ACPI_BUTTON_HID_SLEEPF);
                break;
        }
}

static int acpi_device_set_context(struct acpi_device *device)
{
        acpi_status status;

        /*
         * Context
         * -------
         * Attach this 'struct acpi_device' to the ACPI object.  This makes
         * resolutions from handle->device very efficient.  Fixed hardware
         * devices have no handles, so we skip them.
         */
        if (!device->handle)
                return 0;

        status = acpi_attach_data(device->handle,
                                  acpi_bus_data_handler, device);
        if (ACPI_SUCCESS(status))
                return 0;

        printk(KERN_ERR PREFIX "Error attaching device data\n");
        return -ENODEV;
}

static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
{
        if (!dev)
                return -EINVAL;

        dev->removal_type = ACPI_BUS_REMOVAL_EJECT;
        device_release_driver(&dev->dev);

        if (!rmdevice)
                return 0;

        /*
         * unbind _ADR-Based Devices when hot removal
         */
        if (dev->flags.bus_address) {
                if ((dev->parent) && (dev->parent->ops.unbind))
                        dev->parent->ops.unbind(dev);
        }
        acpi_device_unregister(dev, ACPI_BUS_REMOVAL_EJECT);

        return 0;
}

static int acpi_add_single_object(struct acpi_device **child,
                                  acpi_handle handle, int type,
                                  unsigned long long sta,
                                  struct acpi_bus_ops *ops)
{
        int result;
        struct acpi_device *device;
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

        device = kzalloc(sizeof(struct acpi_device), GFP_KERNEL);
        if (!device) {
                printk(KERN_ERR PREFIX "Memory allocation error\n");
                return -ENOMEM;
        }

        INIT_LIST_HEAD(&device->pnp.ids);
        device->device_type = type;
        device->handle = handle;
        device->parent = acpi_bus_get_parent(handle);
        device->bus_ops = *ops; /* workround for not call .start */
        STRUCT_TO_INT(device->status) = sta;

        acpi_device_get_busid(device);

        /*
         * Flags
         * -----
         * Note that we only look for object handles -- cannot evaluate objects
         * until we know the device is present and properly initialized.
         */
        result = acpi_bus_get_flags(device);
        if (result)
                goto end;

        /*
         * Initialize Device
         * -----------------
         * TBD: Synch with Core's enumeration/initialization process.
         */
        acpi_device_set_id(device);

        /*
         * Power Management
         * ----------------
         */
        if (device->flags.power_manageable) {
                result = acpi_bus_get_power_flags(device);
                if (result)
                        goto end;
        }

        /*
         * Wakeup device management
         *-----------------------
         */
        acpi_bus_get_wakeup_device_flags(device);

        /*
         * Performance Management
         * ----------------------
         */
        if (device->flags.performance_manageable) {
                result = acpi_bus_get_perf_flags(device);
                if (result)
                        goto end;
        }

        if ((result = acpi_device_set_context(device)))
                goto end;

        result = acpi_device_register(device);

        /*
         * Bind _ADR-Based Devices when hot add
         */
        if (device->flags.bus_address) {
                if (device->parent && device->parent->ops.bind)
                        device->parent->ops.bind(device);
        }

end:
        if (!result) {
                acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                        "Adding %s [%s] parent %s\n", dev_name(&device->dev),
                         (char *) buffer.pointer,
                         device->parent ? dev_name(&device->parent->dev) :
                                          "(null)"));
                kfree(buffer.pointer);
                *child = device;
        } else
                acpi_device_release(&device->dev);

        return result;
}

#define ACPI_STA_DEFAULT (ACPI_STA_DEVICE_PRESENT | ACPI_STA_DEVICE_ENABLED | \
                          ACPI_STA_DEVICE_UI      | ACPI_STA_DEVICE_FUNCTIONING)

static void acpi_bus_add_power_resource(acpi_handle handle)
{
        struct acpi_bus_ops ops = {
                .acpi_op_add = 1,
                .acpi_op_start = 1,
        };
        struct acpi_device *device = NULL;

        acpi_bus_get_device(handle, &device);
        if (!device)
                acpi_add_single_object(&device, handle, ACPI_BUS_TYPE_POWER,
                                        ACPI_STA_DEFAULT, &ops);
}

static int acpi_bus_type_and_status(acpi_handle handle, int *type,
                                    unsigned long long *sta)
{
        acpi_status status;
        acpi_object_type acpi_type;

        status = acpi_get_type(handle, &acpi_type);
        if (ACPI_FAILURE(status))
                return -ENODEV;

        switch (acpi_type) {
        case ACPI_TYPE_ANY:             /* for ACPI_ROOT_OBJECT */
        case ACPI_TYPE_DEVICE:
                *type = ACPI_BUS_TYPE_DEVICE;
                status = acpi_bus_get_status_handle(handle, sta);
                if (ACPI_FAILURE(status))
                        return -ENODEV;
                break;
        case ACPI_TYPE_PROCESSOR:
                *type = ACPI_BUS_TYPE_PROCESSOR;
                status = acpi_bus_get_status_handle(handle, sta);
                if (ACPI_FAILURE(status))
                        return -ENODEV;
                break;
        case ACPI_TYPE_THERMAL:
                *type = ACPI_BUS_TYPE_THERMAL;
                *sta = ACPI_STA_DEFAULT;
                break;
        case ACPI_TYPE_POWER:
                *type = ACPI_BUS_TYPE_POWER;
                *sta = ACPI_STA_DEFAULT;
                break;
        default:
                return -ENODEV;
        }

        return 0;
}

static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl,
                                      void *context, void **return_value)
{
        struct acpi_bus_ops *ops = context;
        int type;
        unsigned long long sta;
        struct acpi_device *device;
        acpi_status status;
        int result;

        result = acpi_bus_type_and_status(handle, &type, &sta);
        if (result)
                return AE_OK;

        if (!(sta & ACPI_STA_DEVICE_PRESENT) &&
            !(sta & ACPI_STA_DEVICE_FUNCTIONING)) {
                struct acpi_device_wakeup wakeup;
                acpi_handle temp;

                status = acpi_get_handle(handle, "_PRW", &temp);
                if (ACPI_SUCCESS(status))
                        acpi_bus_extract_wakeup_device_power_package(handle,
                                                                     &wakeup);
                return AE_CTRL_DEPTH;
        }

        /*
         * We may already have an acpi_device from a previous enumeration.  If
         * so, we needn't add it again, but we may still have to start it.
         */
        device = NULL;
        acpi_bus_get_device(handle, &device);
        if (ops->acpi_op_add && !device) {
                acpi_add_single_object(&device, handle, type, sta, ops);
                /* Is the device a known good platform device? */
                if (device
                    && !acpi_match_device_ids(device, acpi_platform_device_ids))
                        acpi_create_platform_device(device);
        }

        if (!device)
                return AE_CTRL_DEPTH;

        if (ops->acpi_op_start && !(ops->acpi_op_add)) {
                status = acpi_start_single_object(device);
                if (ACPI_FAILURE(status))
                        return AE_CTRL_DEPTH;
        }

        if (!*return_value)
                *return_value = device;
        return AE_OK;
}

static int acpi_bus_scan(acpi_handle handle, struct acpi_bus_ops *ops,
                         struct acpi_device **child)
{
        acpi_status status;
        void *device = NULL;

        status = acpi_bus_check_add(handle, 0, ops, &device);
        if (ACPI_SUCCESS(status))
                acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
                                    acpi_bus_check_add, NULL, ops, &device);

        if (child)
                *child = device;

        if (device)
                return 0;
        else
                return -ENODEV;
}

/*
 * acpi_bus_add and acpi_bus_start
 *
 * scan a given ACPI tree and (probably recently hot-plugged)
 * create and add or starts found devices.
 *
 * If no devices were found -ENODEV is returned which does not
 * mean that this is a real error, there just have been no suitable
 * ACPI objects in the table trunk from which the kernel could create
 * a device and add/start an appropriate driver.
 */

int
acpi_bus_add(struct acpi_device **child,
             struct acpi_device *parent, acpi_handle handle, int type)
{
        struct acpi_bus_ops ops;

        memset(&ops, 0, sizeof(ops));
        ops.acpi_op_add = 1;

        return acpi_bus_scan(handle, &ops, child);
}
EXPORT_SYMBOL(acpi_bus_add);

int acpi_bus_start(struct acpi_device *device)
{
        struct acpi_bus_ops ops;
        int result;

        if (!device)
                return -EINVAL;

        memset(&ops, 0, sizeof(ops));
        ops.acpi_op_start = 1;

        result = acpi_bus_scan(device->handle, &ops, NULL);

        acpi_update_all_gpes();

        return result;
}
EXPORT_SYMBOL(acpi_bus_start);

int acpi_bus_trim(struct acpi_device *start, int rmdevice)
{
        acpi_status status;
        struct acpi_device *parent, *child;
        acpi_handle phandle, chandle;
        acpi_object_type type;
        u32 level = 1;
        int err = 0;

        parent = start;
        phandle = start->handle;
        child = chandle = NULL;

        while ((level > 0) && parent && (!err)) {
                status = acpi_get_next_object(ACPI_TYPE_ANY, phandle,
                                              chandle, &chandle);

                /*
                 * If this scope is exhausted then move our way back up.
                 */
                if (ACPI_FAILURE(status)) {
                        level--;
                        chandle = phandle;
                        acpi_get_parent(phandle, &phandle);
                        child = parent;
                        parent = parent->parent;

                        if (level == 0)
                                err = acpi_bus_remove(child, rmdevice);
                        else
                                err = acpi_bus_remove(child, 1);

                        continue;
                }

                status = acpi_get_type(chandle, &type);
                if (ACPI_FAILURE(status)) {
                        continue;
                }
                /*
                 * If there is a device corresponding to chandle then
                 * parse it (depth-first).
                 */
                if (acpi_bus_get_device(chandle, &child) == 0) {
                        level++;
                        phandle = chandle;
                        chandle = NULL;
                        parent = child;
                }
                continue;
        }
        return err;
}
EXPORT_SYMBOL_GPL(acpi_bus_trim);

static int acpi_bus_scan_fixed(void)
{
        int result = 0;
        struct acpi_device *device = NULL;
        struct acpi_bus_ops ops;

        memset(&ops, 0, sizeof(ops));
        ops.acpi_op_add = 1;
        ops.acpi_op_start = 1;

        /*
         * Enumerate all fixed-feature devices.
         */
        if ((acpi_gbl_FADT.flags & ACPI_FADT_POWER_BUTTON) == 0) {
                result = acpi_add_single_object(&device, NULL,
                                                ACPI_BUS_TYPE_POWER_BUTTON,
                                                ACPI_STA_DEFAULT,
                                                &ops);
                device_init_wakeup(&device->dev, true);
        }

        if ((acpi_gbl_FADT.flags & ACPI_FADT_SLEEP_BUTTON) == 0) {
                result = acpi_add_single_object(&device, NULL,
                                                ACPI_BUS_TYPE_SLEEP_BUTTON,
                                                ACPI_STA_DEFAULT,
                                                &ops);
        }

        return result;
}

int __init acpi_scan_init(void)
{
        int result;
        struct acpi_bus_ops ops;

        memset(&ops, 0, sizeof(ops));
        ops.acpi_op_add = 1;
        ops.acpi_op_start = 1;

        result = bus_register(&acpi_bus_type);
        if (result) {
                /* We don't want to quit even if we failed to add suspend/resume */
                printk(KERN_ERR PREFIX "Could not register bus type\n");
        }

        acpi_power_init();

        /*
         * Enumerate devices in the ACPI namespace.
         */
        result = acpi_bus_scan(ACPI_ROOT_OBJECT, &ops, &acpi_root);

        if (!result)
                result = acpi_bus_scan_fixed();

        if (result)
                acpi_device_unregister(acpi_root, ACPI_BUS_REMOVAL_NORMAL);
        else
                acpi_update_all_gpes();

        return result;
}