PL281/Q0/kernel-3.18/drivers/acpi/scan.c

/*
 * 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 <asm/pgtable.h>

#include "internal.h"

#define _COMPONENT		ACPI_BUS_COMPONENT
ACPI_MODULE_NAME("scan");
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)

#define INVALID_ACPI_HANDLE	((acpi_handle)empty_zero_page)

/*
 * If set, devices will be hot-removed even if they cannot be put offline
 * gracefully (from the kernel's standpoint).
 */
bool acpi_force_hot_remove;

static const char *dummy_hid = "device";

static LIST_HEAD(acpi_bus_id_list);
static DEFINE_MUTEX(acpi_scan_lock);
static LIST_HEAD(acpi_scan_handlers_list);
DEFINE_MUTEX(acpi_device_lock);
LIST_HEAD(acpi_wakeup_device_list);
static DEFINE_MUTEX(acpi_hp_context_lock);

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

void acpi_scan_lock_acquire(void)
{
	mutex_lock(&acpi_scan_lock);
}
EXPORT_SYMBOL_GPL(acpi_scan_lock_acquire);

void acpi_scan_lock_release(void)
{
	mutex_unlock(&acpi_scan_lock);
}
EXPORT_SYMBOL_GPL(acpi_scan_lock_release);

void acpi_lock_hp_context(void)
{
	mutex_lock(&acpi_hp_context_lock);
}

void acpi_unlock_hp_context(void)
{
	mutex_unlock(&acpi_hp_context_lock);
}

void acpi_initialize_hp_context(struct acpi_device *adev,
				struct acpi_hotplug_context *hp,
				int (*notify)(struct acpi_device *, u32),
				void (*uevent)(struct acpi_device *, u32))
{
	acpi_lock_hp_context();
	hp->notify = notify;
	hp->uevent = uevent;
	acpi_set_hp_context(adev, hp);
	acpi_unlock_hp_context();
}
EXPORT_SYMBOL_GPL(acpi_initialize_hp_context);

int acpi_scan_add_handler(struct acpi_scan_handler *handler)
{
	if (!handler)
		return -EINVAL;

	list_add_tail(&handler->list_node, &acpi_scan_handlers_list);
	return 0;
}

int acpi_scan_add_handler_with_hotplug(struct acpi_scan_handler *handler,
				       const char *hotplug_profile_name)
{
	int error;

	error = acpi_scan_add_handler(handler);
	if (error)
		return error;

	acpi_sysfs_add_hotplug_profile(&handler->hotplug, hotplug_profile_name);
	return 0;
}

/*
 * 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"
 * Return: 0: no _HID and no _CID
 *         -EINVAL: output error
 *         -ENOMEM: output is truncated
*/
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)
			return -EINVAL;
		if (count >= size)
			return -ENOMEM;
		len += count;
		size -= count;
	}

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

/*
 * acpi_companion_match() - Can we match via ACPI companion device
 * @dev: Device in question
 *
 * Check if the given device has an ACPI companion and if that companion has
 * a valid list of PNP IDs, and if the device is the first (primary) physical
 * device associated with it.
 *
 * If multiple physical devices are attached to a single ACPI companion, we need
 * to be careful.  The usage scenario for this kind of relationship is that all
 * of the physical devices in question use resources provided by the ACPI
 * companion.  A typical case is an MFD device where all the sub-devices share
 * the parent's ACPI companion.  In such cases we can only allow the primary
 * (first) physical device to be matched with the help of the companion's PNP
 * IDs.
 *
 * Additional physical devices sharing the ACPI companion can still use
 * resources available from it but they will be matched normally using functions
 * provided by their bus types (and analogously for their modalias).
 */
static bool acpi_companion_match(const struct device *dev)
{
	struct acpi_device *adev;
	bool ret;

	adev = ACPI_COMPANION(dev);
	if (!adev)
		return false;

	if (list_empty(&adev->pnp.ids))
		return false;

	mutex_lock(&adev->physical_node_lock);
	if (list_empty(&adev->physical_node_list)) {
		ret = false;
	} else {
		const struct acpi_device_physical_node *node;

		node = list_first_entry(&adev->physical_node_list,
					struct acpi_device_physical_node, node);
		ret = node->dev == dev;
	}
	mutex_unlock(&adev->physical_node_lock);

	return ret;
}

/*
 * Creates uevent modalias field for ACPI enumerated devices.
 * Because the other buses does not support ACPI HIDs & CIDs.
 * e.g. for a device with hid:IBM0001 and cid:ACPI0001 you get:
 * "acpi:IBM0001:ACPI0001"
 */
int acpi_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env)
{
	int len;

	if (!acpi_companion_match(dev))
		return -ENODEV;

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

/*
 * Creates modalias sysfs attribute for ACPI enumerated devices.
 * Because the other buses does not support ACPI HIDs & CIDs.
 * e.g. for a device with hid:IBM0001 and cid:ACPI0001 you get:
 * "acpi:IBM0001:ACPI0001"
 */
int acpi_device_modalias(struct device *dev, char *buf, int size)
{
	int len;

	if (!acpi_companion_match(dev))
		return -ENODEV;

	len = create_modalias(ACPI_COMPANION(dev), buf, size -1);
	if (len <= 0)
		return len;
	buf[len++] = '\n';
	return len;
}
EXPORT_SYMBOL_GPL(acpi_device_modalias);

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;

	len = create_modalias(acpi_dev, buf, 1024);
	if (len <= 0)
		return len;
	buf[len++] = '\n';
	return len;
}
static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);

bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
{
	struct acpi_device_physical_node *pn;
	bool offline = true;

	/*
	 * acpi_container_offline() calls this for all of the container's
	 * children under the container's physical_node_lock lock.
	 */
	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);

	list_for_each_entry(pn, &adev->physical_node_list, node)
		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
			if (uevent)
				kobject_uevent(&pn->dev->kobj, KOBJ_CHANGE);

			offline = false;
			break;
		}

	mutex_unlock(&adev->physical_node_lock);
	return offline;
}

static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data,
				    void **ret_p)
{
	struct acpi_device *device = NULL;
	struct acpi_device_physical_node *pn;
	bool second_pass = (bool)data;
	acpi_status status = AE_OK;

	if (acpi_bus_get_device(handle, &device))
		return AE_OK;

	if (device->handler && !device->handler->hotplug.enabled) {
		*ret_p = &device->dev;
		return AE_SUPPORT;
	}

	mutex_lock(&device->physical_node_lock);

	list_for_each_entry(pn, &device->physical_node_list, node) {
		int ret;

		if (second_pass) {
			/* Skip devices offlined by the first pass. */
			if (pn->put_online)
				continue;
		} else {
			pn->put_online = false;
		}
		ret = device_offline(pn->dev);
		if (acpi_force_hot_remove)
			continue;

		if (ret >= 0) {
			pn->put_online = !ret;
		} else {
			*ret_p = pn->dev;
			if (second_pass) {
				status = AE_ERROR;
				break;
			}
		}
	}

	mutex_unlock(&device->physical_node_lock);

	return status;
}

static acpi_status acpi_bus_online(acpi_handle handle, u32 lvl, void *data,
				   void **ret_p)
{
	struct acpi_device *device = NULL;
	struct acpi_device_physical_node *pn;

	if (acpi_bus_get_device(handle, &device))
		return AE_OK;

	mutex_lock(&device->physical_node_lock);

	list_for_each_entry(pn, &device->physical_node_list, node)
		if (pn->put_online) {
			device_online(pn->dev);
			pn->put_online = false;
		}

	mutex_unlock(&device->physical_node_lock);

	return AE_OK;
}

static int acpi_scan_try_to_offline(struct acpi_device *device)
{
	acpi_handle handle = device->handle;
	struct device *errdev = NULL;
	acpi_status status;

	/*
	 * Carry out two passes here and ignore errors in the first pass,
	 * because if the devices in question are memory blocks and
	 * CONFIG_MEMCG is set, one of the blocks may hold data structures
	 * that the other blocks depend on, but it is not known in advance which
	 * block holds them.
	 *
	 * If the first pass is successful, the second one isn't needed, though.
	 */
	status = acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
				     NULL, acpi_bus_offline, (void *)false,
				     (void **)&errdev);
	if (status == AE_SUPPORT) {
		dev_warn(errdev, "Offline disabled.\n");
		acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
				    acpi_bus_online, NULL, NULL, NULL);
		return -EPERM;
	}
	acpi_bus_offline(handle, 0, (void *)false, (void **)&errdev);
	if (errdev) {
		errdev = NULL;
		acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
				    NULL, acpi_bus_offline, (void *)true,
				    (void **)&errdev);
		if (!errdev || acpi_force_hot_remove)
			acpi_bus_offline(handle, 0, (void *)true,
					 (void **)&errdev);

		if (errdev && !acpi_force_hot_remove) {
			dev_warn(errdev, "Offline failed.\n");
			acpi_bus_online(handle, 0, NULL, NULL);
			acpi_walk_namespace(ACPI_TYPE_ANY, handle,
					    ACPI_UINT32_MAX, acpi_bus_online,
					    NULL, NULL, NULL);
			return -EBUSY;
		}
	}
	return 0;
}

static int acpi_scan_hot_remove(struct acpi_device *device)
{
	acpi_handle handle = device->handle;
	unsigned long long sta;
	acpi_status status;

	if (device->handler && device->handler->hotplug.demand_offline
	    && !acpi_force_hot_remove) {
		if (!acpi_scan_is_offline(device, true))
			return -EBUSY;
	} else {
		int error = acpi_scan_try_to_offline(device);
		if (error)
			return error;
	}

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

	acpi_bus_trim(device);

	acpi_evaluate_lck(handle, 0);
	/*
	 * TBD: _EJD support.
	 */
	status = acpi_evaluate_ej0(handle);
	if (status == AE_NOT_FOUND)
		return -ENODEV;
	else if (ACPI_FAILURE(status))
		return -EIO;

	/*
	 * Verify if eject was indeed successful.  If not, log an error
	 * message.  No need to call _OST since _EJ0 call was made OK.
	 */
	status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
	if (ACPI_FAILURE(status)) {
		acpi_handle_warn(handle,
			"Status check after eject failed (0x%x)\n", status);
	} else if (sta & ACPI_STA_DEVICE_ENABLED) {
		acpi_handle_warn(handle,
			"Eject incomplete - status 0x%llx\n", sta);
	}

	return 0;
}

static int acpi_scan_device_not_present(struct acpi_device *adev)
{
	if (!acpi_device_enumerated(adev)) {
		dev_warn(&adev->dev, "Still not present\n");
		return -EALREADY;
	}
	acpi_bus_trim(adev);
	return 0;
}

static int acpi_scan_device_check(struct acpi_device *adev)
{
	int error;

	acpi_bus_get_status(adev);
	if (adev->status.present || adev->status.functional) {
		/*
		 * This function is only called for device objects for which
		 * matching scan handlers exist.  The only situation in which
		 * the scan handler is not attached to this device object yet
		 * is when the device has just appeared (either it wasn't
		 * present at all before or it was removed and then added
		 * again).
		 */
		if (adev->handler) {
			dev_warn(&adev->dev, "Already enumerated\n");
			return -EALREADY;
		}
		error = acpi_bus_scan(adev->handle);
		if (error) {
			dev_warn(&adev->dev, "Namespace scan failure\n");
			return error;
		}
		if (!adev->handler) {
			dev_warn(&adev->dev, "Enumeration failure\n");
			error = -ENODEV;
		}
	} else {
		error = acpi_scan_device_not_present(adev);
	}
	return error;
}

static int acpi_scan_bus_check(struct acpi_device *adev)
{
	struct acpi_scan_handler *handler = adev->handler;
	struct acpi_device *child;
	int error;

	acpi_bus_get_status(adev);
	if (!(adev->status.present || adev->status.functional)) {
		acpi_scan_device_not_present(adev);
		return 0;
	}
	if (handler && handler->hotplug.scan_dependent)
		return handler->hotplug.scan_dependent(adev);

	error = acpi_bus_scan(adev->handle);
	if (error) {
		dev_warn(&adev->dev, "Namespace scan failure\n");
		return error;
	}
	list_for_each_entry(child, &adev->children, node) {
		error = acpi_scan_bus_check(child);
		if (error)
			return error;
	}
	return 0;
}

static int acpi_generic_hotplug_event(struct acpi_device *adev, u32 type)
{
	switch (type) {
	case ACPI_NOTIFY_BUS_CHECK:
		return acpi_scan_bus_check(adev);
	case ACPI_NOTIFY_DEVICE_CHECK:
		return acpi_scan_device_check(adev);
	case ACPI_NOTIFY_EJECT_REQUEST:
	case ACPI_OST_EC_OSPM_EJECT:
		if (adev->handler && !adev->handler->hotplug.enabled) {
			dev_info(&adev->dev, "Eject disabled\n");
			return -EPERM;
		}
		acpi_evaluate_ost(adev->handle, ACPI_NOTIFY_EJECT_REQUEST,
				  ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
		return acpi_scan_hot_remove(adev);
	}
	return -EINVAL;
}

void acpi_device_hotplug(struct acpi_device *adev, u32 src)
{
	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
	int error = -ENODEV;

	lock_device_hotplug();
	mutex_lock(&acpi_scan_lock);

	/*
	 * The device object's ACPI handle cannot become invalid as long as we
	 * are holding acpi_scan_lock, but it might have become invalid before
	 * that lock was acquired.
	 */
	if (adev->handle == INVALID_ACPI_HANDLE)
		goto err_out;

	if (adev->flags.is_dock_station) {
		error = dock_notify(adev, src);
	} else if (adev->flags.hotplug_notify) {
		error = acpi_generic_hotplug_event(adev, src);
		if (error == -EPERM) {
			ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
			goto err_out;
		}
	} else {
		int (*notify)(struct acpi_device *, u32);

		acpi_lock_hp_context();
		notify = adev->hp ? adev->hp->notify : NULL;
		acpi_unlock_hp_context();
		/*
		 * There may be additional notify handlers for device objects
		 * without the .event() callback, so ignore them here.
		 */
		if (notify)
			error = notify(adev, src);
		else
			goto out;
	}
	if (!error)
		ost_code = ACPI_OST_SC_SUCCESS;

 err_out:
	acpi_evaluate_ost(adev->handle, src, ost_code, NULL);

 out:
	acpi_bus_put_acpi_device(adev);
	mutex_unlock(&acpi_scan_lock);
	unlock_device_hotplug();
}

static ssize_t real_power_state_show(struct device *dev,
				     struct device_attribute *attr, char *buf)
{
	struct acpi_device *adev = to_acpi_device(dev);
	int state;
	int ret;

	ret = acpi_device_get_power(adev, &state);
	if (ret)
		return ret;

	return sprintf(buf, "%s\n", acpi_power_state_string(state));
}

static DEVICE_ATTR(real_power_state, 0444, real_power_state_show, NULL);

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

	return sprintf(buf, "%s\n", acpi_power_state_string(adev->power.state));
}

static DEVICE_ATTR(power_state, 0444, power_state_show, NULL);

static ssize_t
acpi_eject_store(struct device *d, struct device_attribute *attr,
		const char *buf, size_t count)
{
	struct acpi_device *acpi_device = to_acpi_device(d);
	acpi_object_type not_used;
	acpi_status status;

	if (!count || buf[0] != '1')
		return -EINVAL;

	if ((!acpi_device->handler || !acpi_device->handler->hotplug.enabled)
	    && !acpi_device->driver)
		return -ENODEV;

	status = acpi_get_type(acpi_device->handle, &not_used);
	if (ACPI_FAILURE(status) || !acpi_device->flags.ejectable)
		return -ENODEV;

	get_device(&acpi_device->dev);
	status = acpi_hotplug_schedule(acpi_device, ACPI_OST_EC_OSPM_EJECT);
	if (ACPI_SUCCESS(status))
		return count;

	put_device(&acpi_device->dev);
	acpi_evaluate_ost(acpi_device->handle, ACPI_OST_EC_OSPM_EJECT,
			  ACPI_OST_SC_NON_SPECIFIC_FAILURE, NULL);
	return status == AE_NO_MEMORY ? -ENOMEM : -EAGAIN;
}

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);
	acpi_status status;
	unsigned long long sun;

	status = acpi_evaluate_integer(acpi_dev->handle, "_SUN", NULL, &sun);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	return sprintf(buf, "%llu\n", sun);
}
static DEVICE_ATTR(sun, 0444, acpi_device_sun_show, NULL);

static ssize_t status_show(struct device *dev, struct device_attribute *attr,
				char *buf) {
	struct acpi_device *acpi_dev = to_acpi_device(dev);
	acpi_status status;
	unsigned long long sta;

	status = acpi_evaluate_integer(acpi_dev->handle, "_STA", NULL, &sta);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	return sprintf(buf, "%llu\n", sta);
}
static DEVICE_ATTR_RO(status);

static int acpi_device_setup_files(struct acpi_device *dev)
{
	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
	acpi_status status;
	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
	 */
	if (acpi_has_method(dev->handle, "_STR")) {
		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->pnp.type.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);

	if (acpi_has_method(dev->handle, "_SUN")) {
		result = device_create_file(&dev->dev, &dev_attr_sun);
		if (result)
			goto end;
	}

	if (acpi_has_method(dev->handle, "_STA")) {
		result = device_create_file(&dev->dev, &dev_attr_status);
		if (result)
			goto end;
	}

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

	if (dev->flags.power_manageable) {
		result = device_create_file(&dev->dev, &dev_attr_power_state);
		if (result)
			return result;

		if (dev->power.flags.power_resources)
			result = device_create_file(&dev->dev,
						    &dev_attr_real_power_state);
	}

end:
	return result;
}

static void acpi_device_remove_files(struct acpi_device *dev)
{
	if (dev->flags.power_manageable) {
		device_remove_file(&dev->dev, &dev_attr_power_state);
		if (dev->power.flags.power_resources)
			device_remove_file(&dev->dev,
					   &dev_attr_real_power_state);
	}

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

	if (acpi_has_method(dev->handle, "_SUN"))
		device_remove_file(&dev->dev, &dev_attr_sun);

	if (dev->pnp.unique_id)
		device_remove_file(&dev->dev, &dev_attr_uid);
	if (dev->pnp.type.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 (acpi_has_method(dev->handle, "_STA"))
		device_remove_file(&dev->dev, &dev_attr_status);
	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;
	acpi_handle handle = ACPI_HANDLE(dev);

	if (!ids || !handle || acpi_bus_get_device(handle, &adev))
		return NULL;

	if (!acpi_companion_match(dev))
		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_power_resources_lists(struct acpi_device *device)
{
	int i;

	if (device->wakeup.flags.valid)
		acpi_power_resources_list_free(&device->wakeup.resources);

	if (!device->power.flags.power_resources)
		return;

	for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++) {
		struct acpi_device_power_state *ps = &device->power.states[i];
		acpi_power_resources_list_free(&ps->resources);
	}
}

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

	acpi_free_properties(acpi_dev);
	acpi_free_pnp_ids(&acpi_dev->pnp);
	acpi_free_power_resources_lists(acpi_dev);
	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_dev->flags.match_driver
		&& !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 <= 0)
		return len;
	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 void 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);
}

static acpi_status acpi_device_fixed_event(void *data)
{
	acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_device_notify_fixed, data);
	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_fixed_event,
						     device);
	else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON)
		status =
		    acpi_install_fixed_event_handler(ACPI_EVENT_SLEEP_BUTTON,
						     acpi_device_fixed_event,
						     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_fixed_event);
	else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON)
		acpi_remove_fixed_event_handler(ACPI_EVENT_SLEEP_BUTTON,
						acpi_device_fixed_event);
	else
		acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
					   acpi_device_notify);
}

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;

	if (acpi_dev->handler && !acpi_is_pnp_device(acpi_dev))
		return -EINVAL;

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

	ret = acpi_drv->ops.add(acpi_dev);
	if (ret)
		return ret;

	acpi_dev->driver = acpi_drv;
	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
			  "Driver [%s] successfully bound to device [%s]\n",
			  acpi_drv->name, acpi_dev->pnp.bus_id));

	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->driver = NULL;
			acpi_dev->driver_data = NULL;
			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 0;
}

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->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 void acpi_device_del(struct acpi_device *device)
{
	mutex_lock(&acpi_device_lock);
	if (device->parent)
		list_del(&device->node);

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

	acpi_power_add_remove_device(device, false);
	acpi_device_remove_files(device);
	if (device->remove)
		device->remove(device);

	device_del(&device->dev);
}

static LIST_HEAD(acpi_device_del_list);
static DEFINE_MUTEX(acpi_device_del_lock);

static void acpi_device_del_work_fn(struct work_struct *work_not_used)
{
	for (;;) {
		struct acpi_device *adev;

		mutex_lock(&acpi_device_del_lock);

		if (list_empty(&acpi_device_del_list)) {
			mutex_unlock(&acpi_device_del_lock);
			break;
		}
		adev = list_first_entry(&acpi_device_del_list,
					struct acpi_device, del_list);
		list_del(&adev->del_list);

		mutex_unlock(&acpi_device_del_lock);

		acpi_device_del(adev);
		/*
		 * Drop references to all power resources that might have been
		 * used by the device.
		 */
		acpi_power_transition(adev, ACPI_STATE_D3_COLD);
		put_device(&adev->dev);
	}
}

/**
 * acpi_scan_drop_device - Drop an ACPI device object.
 * @handle: Handle of an ACPI namespace node, not used.
 * @context: Address of the ACPI device object to drop.
 *
 * This is invoked by acpi_ns_delete_node() during the removal of the ACPI
 * namespace node the device object pointed to by @context is attached to.
 *
 * The unregistration is carried out asynchronously to avoid running
 * acpi_device_del() under the ACPICA's namespace mutex and the list is used to
 * ensure the correct ordering (the device objects must be unregistered in the
 * same order in which the corresponding namespace nodes are deleted).
 */
static void acpi_scan_drop_device(acpi_handle handle, void *context)
{
	static DECLARE_WORK(work, acpi_device_del_work_fn);
	struct acpi_device *adev = context;

	mutex_lock(&acpi_device_del_lock);

	/*
	 * Use the ACPI hotplug workqueue which is ordered, so this work item
	 * won't run after any hotplug work items submitted subsequently.  That
	 * prevents attempts to register device objects identical to those being
	 * deleted from happening concurrently (such attempts result from
	 * hotplug events handled via the ACPI hotplug workqueue).  It also will
	 * run after all of the work items submitted previosuly, which helps
	 * those work items to ensure that they are not accessing stale device
	 * objects.
	 */
	if (list_empty(&acpi_device_del_list))
		acpi_queue_hotplug_work(&work);

	list_add_tail(&adev->del_list, &acpi_device_del_list);
	/* Make acpi_ns_validate_handle() return NULL for this handle. */
	adev->handle = INVALID_ACPI_HANDLE;

	mutex_unlock(&acpi_device_del_lock);
}

static int acpi_get_device_data(acpi_handle handle, struct acpi_device **device,
				void (*callback)(void *))
{
	acpi_status status;

	if (!device)
		return -EINVAL;

	status = acpi_get_data_full(handle, acpi_scan_drop_device,
				    (void **)device, callback);
	if (ACPI_FAILURE(status) || !*device) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No context for object [%p]\n",
				  handle));
		return -ENODEV;
	}
	return 0;
}

int acpi_bus_get_device(acpi_handle handle, struct acpi_device **device)
{
	return acpi_get_device_data(handle, device, NULL);
}
EXPORT_SYMBOL(acpi_bus_get_device);

static void get_acpi_device(void *dev)
{
	if (dev)
		get_device(&((struct acpi_device *)dev)->dev);
}

struct acpi_device *acpi_bus_get_acpi_device(acpi_handle handle)
{
	struct acpi_device *adev = NULL;

	acpi_get_device_data(handle, &adev, get_acpi_device);
	return adev;
}

void acpi_bus_put_acpi_device(struct acpi_device *adev)
{
	put_device(&adev->dev);
}

int acpi_device_add(struct acpi_device *device,
		    void (*release)(struct device *))
{
	int result;
	struct acpi_device_bus_id *acpi_device_bus_id, *new_bus_id;
	int found = 0;

	if (device->handle) {
		acpi_status status;

		status = acpi_attach_data(device->handle, acpi_scan_drop_device,
					  device);
		if (ACPI_FAILURE(status)) {
			acpi_handle_err(device->handle,
					"Unable to attach device data\n");
			return -ENODEV;
		}
	}

	/*
	 * 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);
	INIT_LIST_HEAD(&device->del_list);
	mutex_init(&device->physical_node_lock);

	new_bus_id = kzalloc(sizeof(struct acpi_device_bus_id), GFP_KERNEL);
	if (!new_bus_id) {
		pr_err(PREFIX "Memory allocation error\n");
		result = -ENOMEM;
		goto err_detach;
	}

	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 = release;
	result = device_add(&device->dev);
	if (result) {
		dev_err(&device->dev, "Error registering device\n");
		goto err;
	}

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

	return 0;

 err:
	mutex_lock(&acpi_device_lock);
	if (device->parent)
		list_del(&device->node);
	list_del(&device->wakeup_list);
	mutex_unlock(&acpi_device_lock);

 err_detach:
	acpi_detach_data(device->handle, acpi_scan_drop_device);
	return result;
}

/* --------------------------------------------------------------------------
                                 Driver Management
   -------------------------------------------------------------------------- */
/**
 * 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 ACPI 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)
{
	struct acpi_device *device = NULL;
	acpi_status status;

	/*
	 * 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)
		return acpi_root;

	do {
		status = acpi_get_parent(handle, &handle);
		if (ACPI_FAILURE(status))
			return status == AE_NULL_ENTRY ? NULL : acpi_root;
	} while (acpi_bus_get_device(handle, &device));
	return device;
}

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);

static int 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 err = -ENODATA;

	if (!wakeup)
		return -EINVAL;

	INIT_LIST_HEAD(&wakeup->resources);

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

	package = (union acpi_object *)buffer.pointer;

	if (!package || package->package.count < 2)
		goto out;

	element = &(package->package.elements[0]);
	if (!element)
		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))
			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 {
		goto out;
	}

	element = &(package->package.elements[1]);
	if (element->type != ACPI_TYPE_INTEGER)
		goto out;

	wakeup->sleep_state = element->integer.value;

	err = acpi_extract_power_resources(package, 2, &wakeup->resources);
	if (err)
		goto out;

	if (!list_empty(&wakeup->resources)) {
		int sleep_state;

		err = acpi_power_wakeup_list_init(&wakeup->resources,
						  &sleep_state);
		if (err) {
			acpi_handle_warn(handle, "Retrieving current states "
					 "of wakeup power resources failed\n");
			acpi_power_resources_list_free(&wakeup->resources);
			goto out;
		}
		if (sleep_state < wakeup->sleep_state) {
			acpi_handle_warn(handle, "Overriding _PRW sleep state "
					 "(S%d) by S%d from power resources\n",
					 (int)wakeup->sleep_state, sleep_state);
			wakeup->sleep_state = sleep_state;
		}
	}

 out:
	kfree(buffer.pointer);
	return err;
}

static void acpi_wakeup_gpe_init(struct acpi_device *device)
{
	struct acpi_device_id button_device_ids[] = {
		{"PNP0C0C", 0},
		{"PNP0C0D", 0},
		{"PNP0C0E", 0},
		{"", 0},
	};
	struct acpi_device_wakeup *wakeup = &device->wakeup;
	acpi_status status;
	acpi_event_status event_status;

	wakeup->flags.notifier_present = 0;

	/* Power button, Lid switch always enable wakeup */
	if (!acpi_match_device_ids(device, button_device_ids)) {
		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 (wakeup->sleep_state == ACPI_STATE_S5)
				wakeup->sleep_state = ACPI_STATE_S4;
		}
		acpi_mark_gpe_for_wake(wakeup->gpe_device, wakeup->gpe_number);
		device_set_wakeup_capable(&device->dev, true);
		return;
	}

	acpi_setup_gpe_for_wake(device->handle, wakeup->gpe_device,
				wakeup->gpe_number);
	status = acpi_get_gpe_status(wakeup->gpe_device, wakeup->gpe_number,
				     &event_status);
	if (ACPI_FAILURE(status))
		return;

	wakeup->flags.run_wake = !!(event_status & ACPI_EVENT_FLAG_HAS_HANDLER);
}

static void acpi_bus_get_wakeup_device_flags(struct acpi_device *device)
{
	int err;

	/* Presence of _PRW indicates wake capable */
	if (!acpi_has_method(device->handle, "_PRW"))
		return;

	err = acpi_bus_extract_wakeup_device_power_package(device->handle,
							   &device->wakeup);
	if (err) {
		dev_err(&device->dev, "_PRW evaluation error: %d\n", err);
		return;
	}

	device->wakeup.flags.valid = 1;
	device->wakeup.prepare_count = 0;
	acpi_wakeup_gpe_init(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.
	 */
	err = acpi_device_sleep_wake(device, 0, 0, 0);
	if (err)
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				"error in _DSW or _PSW evaluation\n"));
}

static void acpi_bus_init_power_state(struct acpi_device *device, int state)
{
	struct acpi_device_power_state *ps = &device->power.states[state];
	char pathname[5] = { '_', 'P', 'R', '0' + state, '\0' };
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	acpi_status status;

	INIT_LIST_HEAD(&ps->resources);

	/* Evaluate "_PRx" to get referenced power resources */
	status = acpi_evaluate_object(device->handle, pathname, NULL, &buffer);
	if (ACPI_SUCCESS(status)) {
		union acpi_object *package = buffer.pointer;

		if (buffer.length && package
		    && package->type == ACPI_TYPE_PACKAGE
		    && package->package.count) {
			int err = acpi_extract_power_resources(package, 0,
							       &ps->resources);
			if (!err)
				device->power.flags.power_resources = 1;
		}
		ACPI_FREE(buffer.pointer);
	}

	/* Evaluate "_PSx" to see if we can do explicit sets */
	pathname[2] = 'S';
	if (acpi_has_method(device->handle, pathname))
		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 (!list_empty(&ps->resources)
	    || (ps->flags.explicit_set && state < 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 */
}

static void acpi_bus_get_power_flags(struct acpi_device *device)
{
	u32 i;

	/* Presence of _PS0|_PR0 indicates 'power manageable' */
	if (!acpi_has_method(device->handle, "_PS0") &&
	    !acpi_has_method(device->handle, "_PR0"))
		return;

	device->flags.power_manageable = 1;

	/*
	 * Power Management Flags
	 */
	if (acpi_has_method(device->handle, "_PSC"))
		device->power.flags.explicit_get = 1;

	if (acpi_has_method(device->handle, "_IRC"))
		device->power.flags.inrush_current = 1;

	if (acpi_has_method(device->handle, "_DSW"))
		device->power.flags.dsw_present = 1;

	/*
	 * Enumerate supported power management states
	 */
	for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++)
		acpi_bus_init_power_state(device, i);

	INIT_LIST_HEAD(&device->power.states[ACPI_STATE_D3_COLD].resources);

	/* 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_COLD].flags.valid = 1;
	device->power.states[ACPI_STATE_D3_COLD].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;

	if (acpi_bus_init_power(device))
		device->flags.power_manageable = 0;
}

static void acpi_bus_get_flags(struct acpi_device *device)
{
	/* Presence of _STA indicates 'dynamic_status' */
	if (acpi_has_method(device->handle, "_STA"))
		device->flags.dynamic_status = 1;

	/* Presence of _RMV indicates 'removable' */
	if (acpi_has_method(device->handle, "_RMV"))
		device->flags.removable = 1;

	/* Presence of _EJD|_EJ0 indicates 'ejectable' */
	if (acpi_has_method(device->handle, "_EJD") ||
	    acpi_has_method(device->handle, "_EJ0"))
		device->flags.ejectable = 1;
}

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_ata_match - see if an acpi object is an ATA device
 *
 * If an acpi object has one of the ACPI ATA methods defined,
 * then we can safely call it an ATA device.
 */
bool acpi_ata_match(acpi_handle handle)
{
	return acpi_has_method(handle, "_GTF") ||
	       acpi_has_method(handle, "_GTM") ||
	       acpi_has_method(handle, "_STM") ||
	       acpi_has_method(handle, "_SDD");
}

/*
 * acpi_bay_match - see if an acpi object 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
 */
bool acpi_bay_match(acpi_handle handle)
{
	acpi_handle phandle;

	if (!acpi_has_method(handle, "_EJ0"))
		return false;
	if (acpi_ata_match(handle))
		return true;
	if (ACPI_FAILURE(acpi_get_parent(handle, &phandle)))
		return false;

	return acpi_ata_match(phandle);
}

bool acpi_device_is_battery(struct acpi_device *adev)
{
	struct acpi_hardware_id *hwid;

	list_for_each_entry(hwid, &adev->pnp.ids, list)
		if (!strcmp("PNP0C0A", hwid->id))
			return true;

	return false;
}

static bool is_ejectable_bay(struct acpi_device *adev)
{
	acpi_handle handle = adev->handle;

	if (acpi_has_method(handle, "_EJ0") && acpi_device_is_battery(adev))
		return true;

	return acpi_bay_match(handle);
}

/*
 * acpi_dock_match - see if an acpi object has a _DCK method
 */
bool acpi_dock_match(acpi_handle handle)
{
	return acpi_has_method(handle, "_DCK");
}

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_pnp *pnp, 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, &pnp->ids);
	pnp->type.hardware_id = 1;
}

/*
 * 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 bool acpi_ibm_smbus_match(acpi_handle handle)
{
	char node_name[ACPI_PATH_SEGMENT_LENGTH];
	struct acpi_buffer path = { sizeof(node_name), node_name };

	if (!dmi_name_in_vendors("IBM"))
		return false;

	/* Look for SMBS object */
	if (ACPI_FAILURE(acpi_get_name(handle, ACPI_SINGLE_NAME, &path)) ||
	    strcmp("SMBS", path.pointer))
		return false;

	/* Does it have the necessary (but misnamed) methods? */
	if (acpi_has_method(handle, "SBI") &&
	    acpi_has_method(handle, "SBR") &&
	    acpi_has_method(handle, "SBW"))
		return true;

	return false;
}

static bool acpi_object_is_system_bus(acpi_handle handle)
{
	acpi_handle tmp;

	if (ACPI_SUCCESS(acpi_get_handle(NULL, "\\_SB", &tmp)) &&
	    tmp == handle)
		return true;
	if (ACPI_SUCCESS(acpi_get_handle(NULL, "\\_TZ", &tmp)) &&
	    tmp == handle)
		return true;

	return false;
}

static void acpi_set_pnp_ids(acpi_handle handle, struct acpi_device_pnp *pnp,
				int device_type)
{
	acpi_status status;
	struct acpi_device_info *info;
	struct acpi_pnp_device_id_list *cid_list;
	int i;

	switch (device_type) {
	case ACPI_BUS_TYPE_DEVICE:
		if (handle == ACPI_ROOT_OBJECT) {
			acpi_add_id(pnp, ACPI_SYSTEM_HID);
			break;
		}

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

		if (info->valid & ACPI_VALID_HID) {
			acpi_add_id(pnp, info->hardware_id.string);
			pnp->type.platform_id = 1;
		}
		if (info->valid & ACPI_VALID_CID) {
			cid_list = &info->compatible_id_list;
			for (i = 0; i < cid_list->count; i++)
				acpi_add_id(pnp, cid_list->ids[i].string);
		}
		if (info->valid & ACPI_VALID_ADR) {
			pnp->bus_address = info->address;
			pnp->type.bus_address = 1;
		}
		if (info->valid & ACPI_VALID_UID)
			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(handle))
			acpi_add_id(pnp, ACPI_VIDEO_HID);
		else if (acpi_bay_match(handle))
			acpi_add_id(pnp, ACPI_BAY_HID);
		else if (acpi_dock_match(handle))
			acpi_add_id(pnp, ACPI_DOCK_HID);
		else if (acpi_ibm_smbus_match(handle))
			acpi_add_id(pnp, ACPI_SMBUS_IBM_HID);
		else if (list_empty(&pnp->ids) &&
			 acpi_object_is_system_bus(handle)) {
			/* \_SB, \_TZ, LNXSYBUS */
			acpi_add_id(pnp, ACPI_BUS_HID);
			strcpy(pnp->device_name, ACPI_BUS_DEVICE_NAME);
			strcpy(pnp->device_class, ACPI_BUS_CLASS);
		}

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

void acpi_free_pnp_ids(struct acpi_device_pnp *pnp)
{
	struct acpi_hardware_id *id, *tmp;

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

void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
			     int type, unsigned long long sta)
{
	INIT_LIST_HEAD(&device->pnp.ids);
	device->device_type = type;
	device->handle = handle;
	device->parent = acpi_bus_get_parent(handle);
	acpi_set_device_status(device, sta);
	acpi_device_get_busid(device);
	acpi_set_pnp_ids(handle, &device->pnp, type);
	acpi_init_properties(device);
	acpi_bus_get_flags(device);
	device->flags.match_driver = false;
	device->flags.initialized = true;
	device->flags.visited = false;
	device_initialize(&device->dev);
	dev_set_uevent_suppress(&device->dev, true);
}

void acpi_device_add_finalize(struct acpi_device *device)
{
	dev_set_uevent_suppress(&device->dev, false);
	kobject_uevent(&device->dev.kobj, KOBJ_ADD);
}

static int acpi_add_single_object(struct acpi_device **child,
				  acpi_handle handle, int type,
				  unsigned long long sta)
{
	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;
	}

	acpi_init_device_object(device, handle, type, sta);
	acpi_bus_get_power_flags(device);
	acpi_bus_get_wakeup_device_flags(device);

	result = acpi_device_add(device, acpi_device_release);
	if (result) {
		acpi_device_release(&device->dev);
		return result;
	}

	acpi_power_add_remove_device(device, true);
	acpi_device_add_finalize(device);
	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Added %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;
	return 0;
}

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;
}

bool acpi_device_is_present(struct acpi_device *adev)
{
	if (adev->status.present || adev->status.functional)
		return true;

	adev->flags.initialized = false;
	return false;
}

static bool acpi_scan_handler_matching(struct acpi_scan_handler *handler,
				       char *idstr,
				       const struct acpi_device_id **matchid)
{
	const struct acpi_device_id *devid;

	if (handler->match)
		return handler->match(idstr, matchid);

	for (devid = handler->ids; devid->id[0]; devid++)
		if (!strcmp((char *)devid->id, idstr)) {
			if (matchid)
				*matchid = devid;

			return true;
		}

	return false;
}

static struct acpi_scan_handler *acpi_scan_match_handler(char *idstr,
					const struct acpi_device_id **matchid)
{
	struct acpi_scan_handler *handler;

	list_for_each_entry(handler, &acpi_scan_handlers_list, list_node)
		if (acpi_scan_handler_matching(handler, idstr, matchid))
			return handler;

	return NULL;
}

void acpi_scan_hotplug_enabled(struct acpi_hotplug_profile *hotplug, bool val)
{
	if (!!hotplug->enabled == !!val)
		return;

	mutex_lock(&acpi_scan_lock);

	hotplug->enabled = val;

	mutex_unlock(&acpi_scan_lock);
}

static void acpi_scan_init_hotplug(struct acpi_device *adev)
{
	struct acpi_hardware_id *hwid;

	if (acpi_dock_match(adev->handle) || is_ejectable_bay(adev)) {
		acpi_dock_add(adev);
		return;
	}
	list_for_each_entry(hwid, &adev->pnp.ids, list) {
		struct acpi_scan_handler *handler;

		handler = acpi_scan_match_handler(hwid->id, NULL);
		if (handler) {
			adev->flags.hotplug_notify = true;
			break;
		}
	}
}

static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
				      void *not_used, void **return_value)
{
	struct acpi_device *device = NULL;
	int type;
	unsigned long long sta;
	int result;

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

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

	if (type == ACPI_BUS_TYPE_POWER) {
		acpi_add_power_resource(handle);
		return AE_OK;
	}

	acpi_add_single_object(&device, handle, type, sta);
	if (!device)
		return AE_CTRL_DEPTH;

	acpi_scan_init_hotplug(device);

 out:
	if (!*return_value)
		*return_value = device;

	return AE_OK;
}

static int acpi_check_spi_i2c_slave(struct acpi_resource *ares, void *data)
{
	bool *is_spi_i2c_slave_p = data;

	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
		return 1;

	/*
	 * devices that are connected to UART still need to be enumerated to
	 * platform bus
	 */
	if (ares->data.common_serial_bus.type != ACPI_RESOURCE_SERIAL_TYPE_UART)
		*is_spi_i2c_slave_p = true;

	 /* no need to do more checking */
	return -1;
}

static void acpi_default_enumeration(struct acpi_device *device)
{
	struct list_head resource_list;
	bool is_spi_i2c_slave = false;

	if (!device->pnp.type.platform_id || device->handler)
		return;

	/*
	 * Do not enemerate SPI/I2C slaves as they will be enuerated by their
	 * respective parents.
	 */
	INIT_LIST_HEAD(&resource_list);
	acpi_dev_get_resources(device, &resource_list, acpi_check_spi_i2c_slave,
			       &is_spi_i2c_slave);
	acpi_dev_free_resource_list(&resource_list);
	if (!is_spi_i2c_slave)
		acpi_create_platform_device(device);
}

static int acpi_scan_attach_handler(struct acpi_device *device)
{
	struct acpi_hardware_id *hwid;
	int ret = 0;

	list_for_each_entry(hwid, &device->pnp.ids, list) {
		const struct acpi_device_id *devid;
		struct acpi_scan_handler *handler;

		handler = acpi_scan_match_handler(hwid->id, &devid);
		if (handler) {
			if (!handler->attach) {
				device->pnp.type.platform_id = 0;
				continue;
			}
			device->handler = handler;
			ret = handler->attach(device, devid);
			if (ret > 0)
				break;

			device->handler = NULL;
			if (ret < 0)
				break;
		}
	}
	if (!ret)
		acpi_default_enumeration(device);

	return ret;
}

static void acpi_bus_attach(struct acpi_device *device)
{
	struct acpi_device *child;
	acpi_handle ejd;
	int ret;

	if (ACPI_SUCCESS(acpi_bus_get_ejd(device->handle, &ejd)))
		register_dock_dependent_device(device, ejd);

	acpi_bus_get_status(device);
	/* Skip devices that are not present. */
	if (!acpi_device_is_present(device)) {
		device->flags.visited = false;
		device->flags.power_manageable = 0;
		return;
	}
	if (device->handler)
		goto ok;

	if (!device->flags.initialized) {
		device->flags.power_manageable =
			device->power.states[ACPI_STATE_D0].flags.valid;
		if (acpi_bus_init_power(device))
			device->flags.power_manageable = 0;

		device->flags.initialized = true;
	}
	device->flags.visited = false;
	ret = acpi_scan_attach_handler(device);
	if (ret < 0)
		return;

	device->flags.match_driver = true;
	if (!ret) {
		ret = device_attach(&device->dev);
		if (ret < 0)
			return;
	}
	device->flags.visited = true;

 ok:
	list_for_each_entry(child, &device->children, node)
		acpi_bus_attach(child);

	if (device->handler && device->handler->hotplug.notify_online)
		device->handler->hotplug.notify_online(device);
}

/**
 * acpi_bus_scan - Add ACPI device node objects in a given namespace scope.
 * @handle: Root of the namespace scope to scan.
 *
 * Scan a given ACPI tree (probably recently hot-plugged) and create and add
 * found devices.
 *
 * If no devices were found, -ENODEV is returned, but it does not mean that
 * there has been 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 an
 * appropriate driver.
 *
 * Must be called under acpi_scan_lock.
 */
int acpi_bus_scan(acpi_handle handle)
{
	void *device = NULL;

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

	if (device) {
		acpi_bus_attach(device);
		return 0;
	}
	return -ENODEV;
}
EXPORT_SYMBOL(acpi_bus_scan);

/**
 * acpi_bus_trim - Detach scan handlers and drivers from ACPI device objects.
 * @adev: Root of the ACPI namespace scope to walk.
 *
 * Must be called under acpi_scan_lock.
 */
void acpi_bus_trim(struct acpi_device *adev)
{
	struct acpi_scan_handler *handler = adev->handler;
	struct acpi_device *child;

	list_for_each_entry_reverse(child, &adev->children, node)
		acpi_bus_trim(child);

	adev->flags.match_driver = false;
	if (handler) {
		if (handler->detach)
			handler->detach(adev);

		adev->handler = NULL;
	} else {
		device_release_driver(&adev->dev);
	}
	/*
	 * Most likely, the device is going away, so put it into D3cold before
	 * that.
	 */
	acpi_device_set_power(adev, ACPI_STATE_D3_COLD);
	adev->flags.initialized = false;
	adev->flags.visited = false;
}
EXPORT_SYMBOL_GPL(acpi_bus_trim);

static int acpi_bus_scan_fixed(void)
{
	int result = 0;

	/*
	 * Enumerate all fixed-feature devices.
	 */
	if (!(acpi_gbl_FADT.flags & ACPI_FADT_POWER_BUTTON)) {
		struct acpi_device *device = NULL;

		result = acpi_add_single_object(&device, NULL,
						ACPI_BUS_TYPE_POWER_BUTTON,
						ACPI_STA_DEFAULT);
		if (result)
			return result;

		device->flags.match_driver = true;
		result = device_attach(&device->dev);
		if (result < 0)
			return result;

		device_init_wakeup(&device->dev, true);
	}

	if (!(acpi_gbl_FADT.flags & ACPI_FADT_SLEEP_BUTTON)) {
		struct acpi_device *device = NULL;

		result = acpi_add_single_object(&device, NULL,
						ACPI_BUS_TYPE_SLEEP_BUTTON,
						ACPI_STA_DEFAULT);
		if (result)
			return result;

		device->flags.match_driver = true;
		result = device_attach(&device->dev);
	}

	return result < 0 ? result : 0;
}

int __init acpi_scan_init(void)
{
	int result;

	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_pci_root_init();
	acpi_pci_link_init();
	acpi_processor_init();
	acpi_lpss_init();
	acpi_cmos_rtc_init();
	acpi_container_init();
	acpi_memory_hotplug_init();
	acpi_pnp_init();
	acpi_int340x_thermal_init();

	mutex_lock(&acpi_scan_lock);
	/*
	 * Enumerate devices in the ACPI namespace.
	 */
	result = acpi_bus_scan(ACPI_ROOT_OBJECT);
	if (result)
		goto out;

	result = acpi_bus_get_device(ACPI_ROOT_OBJECT, &acpi_root);
	if (result)
		goto out;

	/* Fixed feature devices do not exist on HW-reduced platform */
	if (!acpi_gbl_reduced_hardware) {
		result = acpi_bus_scan_fixed();
		if (result) {
			acpi_detach_data(acpi_root->handle,
					 acpi_scan_drop_device);
			acpi_device_del(acpi_root);
			put_device(&acpi_root->dev);
			goto out;
		}
	}

	acpi_update_all_gpes();

 out:
	mutex_unlock(&acpi_scan_lock);
	return result;
}