/*
 *  acpi_power.c - ACPI Bus Power Management ($Revision: 39 $)
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

/*
 * ACPI power-managed devices may be controlled in two ways:
 * 1. via "Device Specific (D-State) Control"
 * 2. via "Power Resource Control".
 * This module is used to manage devices relying on Power Resource Control.
 * 
 * An ACPI "power resource object" describes a software controllable power
 * plane, clock plane, or other resource used by a power managed device.
 * A device may rely on multiple power resources, and a power resource
 * may be shared by multiple devices.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/sysfs.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include "sleep.h"
#include "internal.h"

#define PREFIX "ACPI: "

#define _COMPONENT                      ACPI_POWER_COMPONENT
ACPI_MODULE_NAME("power");
#define ACPI_POWER_CLASS                "power_resource"
#define ACPI_POWER_DEVICE_NAME          "Power Resource"
#define ACPI_POWER_FILE_INFO            "info"
#define ACPI_POWER_FILE_STATUS          "state"
#define ACPI_POWER_RESOURCE_STATE_OFF   0x00
#define ACPI_POWER_RESOURCE_STATE_ON    0x01
#define ACPI_POWER_RESOURCE_STATE_UNKNOWN 0xFF

struct acpi_power_dependent_device {
        struct list_head node;
        struct acpi_device *adev;
        struct work_struct work;
};

struct acpi_power_resource {
        struct acpi_device device;
        struct list_head list_node;
        struct list_head dependent;
        char *name;
        u32 system_level;
        u32 order;
        unsigned int ref_count;
        bool wakeup_enabled;
        struct mutex resource_lock;
};

struct acpi_power_resource_entry {
        struct list_head node;
        struct acpi_power_resource *resource;
};

static LIST_HEAD(acpi_power_resource_list);
static DEFINE_MUTEX(power_resource_list_lock);

/* --------------------------------------------------------------------------
                             Power Resource Management
   -------------------------------------------------------------------------- */

static inline
struct acpi_power_resource *to_power_resource(struct acpi_device *device)
{
        return container_of(device, struct acpi_power_resource, device);
}

static struct acpi_power_resource *acpi_power_get_context(acpi_handle handle)
{
        struct acpi_device *device;

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

        return to_power_resource(device);
}

static int acpi_power_resources_list_add(acpi_handle handle,
                                         struct list_head *list)
{
        struct acpi_power_resource *resource = acpi_power_get_context(handle);
        struct acpi_power_resource_entry *entry;

        if (!resource || !list)
                return -EINVAL;

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

        entry->resource = resource;
        if (!list_empty(list)) {
                struct acpi_power_resource_entry *e;

                list_for_each_entry(e, list, node)
                        if (e->resource->order > resource->order) {
                                list_add_tail(&entry->node, &e->node);
                                return 0;
                        }
        }
        list_add_tail(&entry->node, list);
        return 0;
}

void acpi_power_resources_list_free(struct list_head *list)
{
        struct acpi_power_resource_entry *entry, *e;

        list_for_each_entry_safe(entry, e, list, node) {
                list_del(&entry->node);
                kfree(entry);
        }
}

int acpi_extract_power_resources(union acpi_object *package, unsigned int start,
                                 struct list_head *list)
{
        unsigned int i;
        int err = 0;

        for (i = start; i < package->package.count; i++) {
                union acpi_object *element = &package->package.elements[i];
                acpi_handle rhandle;

                if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
                        err = -ENODATA;
                        break;
                }
                rhandle = element->reference.handle;
                if (!rhandle) {
                        err = -ENODEV;
                        break;
                }
                err = acpi_add_power_resource(rhandle);
                if (err)
                        break;

                err = acpi_power_resources_list_add(rhandle, list);
                if (err)
                        break;
        }
        if (err)
                acpi_power_resources_list_free(list);

        return err;
}

static int acpi_power_get_state(acpi_handle handle, int *state)
{
        acpi_status status = AE_OK;
        unsigned long long sta = 0;
        char node_name[5];
        struct acpi_buffer buffer = { sizeof(node_name), node_name };


        if (!handle || !state)
                return -EINVAL;

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

        *state = (sta & 0x01)?ACPI_POWER_RESOURCE_STATE_ON:
                              ACPI_POWER_RESOURCE_STATE_OFF;

        acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);

        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource [%s] is %s\n",
                          node_name,
                                *state ? "on" : "off"));

        return 0;
}

static int acpi_power_get_list_state(struct list_head *list, int *state)
{
        struct acpi_power_resource_entry *entry;
        int cur_state;

        if (!list || !state)
                return -EINVAL;

        /* The state of the list is 'on' IFF all resources are 'on'. */
        list_for_each_entry(entry, list, node) {
                struct acpi_power_resource *resource = entry->resource;
                acpi_handle handle = resource->device.handle;
                int result;

                mutex_lock(&resource->resource_lock);
                result = acpi_power_get_state(handle, &cur_state);
                mutex_unlock(&resource->resource_lock);
                if (result)
                        return result;

                if (cur_state != ACPI_POWER_RESOURCE_STATE_ON)
                        break;
        }

        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Resource list is %s\n",
                          cur_state ? "on" : "off"));

        *state = cur_state;
        return 0;
}

static void acpi_power_resume_dependent(struct work_struct *work)
{
        struct acpi_power_dependent_device *dep;
        struct acpi_device_physical_node *pn;
        struct acpi_device *adev;
        int state;

        dep = container_of(work, struct acpi_power_dependent_device, work);
        adev = dep->adev;
        if (acpi_power_get_inferred_state(adev, &state))
                return;

        if (state > ACPI_STATE_D0)
                return;

        mutex_lock(&adev->physical_node_lock);

        list_for_each_entry(pn, &adev->physical_node_list, node)
                pm_request_resume(pn->dev);

        list_for_each_entry(pn, &adev->power_dependent, node)
                pm_request_resume(pn->dev);

        mutex_unlock(&adev->physical_node_lock);
}

static int __acpi_power_on(struct acpi_power_resource *resource)
{
        acpi_status status = AE_OK;

        status = acpi_evaluate_object(resource->device.handle, "_ON", NULL, NULL);
        if (ACPI_FAILURE(status))
                return -ENODEV;

        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Power resource [%s] turned on\n",
                          resource->name));

        return 0;
}

static int acpi_power_on_unlocked(struct acpi_power_resource *resource)
{
        int result = 0;

        if (resource->ref_count++) {
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                  "Power resource [%s] already on",
                                  resource->name));
        } else {
                result = __acpi_power_on(resource);
                if (result) {
                        resource->ref_count--;
                } else {
                        struct acpi_power_dependent_device *dep;

                        list_for_each_entry(dep, &resource->dependent, node)
                                schedule_work(&dep->work);
                }
        }
        return result;
}

static int acpi_power_on(struct acpi_power_resource *resource)
{
        int result;

        mutex_lock(&resource->resource_lock);
        result = acpi_power_on_unlocked(resource);
        mutex_unlock(&resource->resource_lock);
        return result;
}

static int __acpi_power_off(struct acpi_power_resource *resource)
{
        acpi_status status;

        status = acpi_evaluate_object(resource->device.handle, "_OFF",
                                      NULL, NULL);
        if (ACPI_FAILURE(status))
                return -ENODEV;

        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Power resource [%s] turned off\n",
                          resource->name));
        return 0;
}

static int acpi_power_off_unlocked(struct acpi_power_resource *resource)
{
        int result = 0;

        if (!resource->ref_count) {
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                  "Power resource [%s] already off",
                                  resource->name));
                return 0;
        }

        if (--resource->ref_count) {
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                  "Power resource [%s] still in use\n",
                                  resource->name));
        } else {
                result = __acpi_power_off(resource);
                if (result)
                        resource->ref_count++;
        }
        return result;
}

static int acpi_power_off(struct acpi_power_resource *resource)
{
        int result;

        mutex_lock(&resource->resource_lock);
        result = acpi_power_off_unlocked(resource);
        mutex_unlock(&resource->resource_lock);
        return result;
}

static int acpi_power_off_list(struct list_head *list)
{
        struct acpi_power_resource_entry *entry;
        int result = 0;

        list_for_each_entry_reverse(entry, list, node) {
                result = acpi_power_off(entry->resource);
                if (result)
                        goto err;
        }
        return 0;

 err:
        list_for_each_entry_continue(entry, list, node)
                acpi_power_on(entry->resource);

        return result;
}

static int acpi_power_on_list(struct list_head *list)
{
        struct acpi_power_resource_entry *entry;
        int result = 0;

        list_for_each_entry(entry, list, node) {
                result = acpi_power_on(entry->resource);
                if (result)
                        goto err;
        }
        return 0;

 err:
        list_for_each_entry_continue_reverse(entry, list, node)
                acpi_power_off(entry->resource);

        return result;
}

static void acpi_power_add_dependent(struct acpi_power_resource *resource,
                                     struct acpi_device *adev)
{
        struct acpi_power_dependent_device *dep;

        mutex_lock(&resource->resource_lock);

        list_for_each_entry(dep, &resource->dependent, node)
                if (dep->adev == adev)
                        goto out;

        dep = kzalloc(sizeof(*dep), GFP_KERNEL);
        if (!dep)
                goto out;

        dep->adev = adev;
        INIT_WORK(&dep->work, acpi_power_resume_dependent);
        list_add_tail(&dep->node, &resource->dependent);

 out:
        mutex_unlock(&resource->resource_lock);
}

static void acpi_power_remove_dependent(struct acpi_power_resource *resource,
                                        struct acpi_device *adev)
{
        struct acpi_power_dependent_device *dep;
        struct work_struct *work = NULL;

        mutex_lock(&resource->resource_lock);

        list_for_each_entry(dep, &resource->dependent, node)
                if (dep->adev == adev) {
                        list_del(&dep->node);
                        work = &dep->work;
                        break;
                }

        mutex_unlock(&resource->resource_lock);

        if (work) {
                cancel_work_sync(work);
                kfree(dep);
        }
}

static struct attribute *attrs[] = {
        NULL,
};

static struct attribute_group attr_groups[] = {
        [ACPI_STATE_D0] = {
                .name = "power_resources_D0",
                .attrs = attrs,
        },
        [ACPI_STATE_D1] = {
                .name = "power_resources_D1",
                .attrs = attrs,
        },
        [ACPI_STATE_D2] = {
                .name = "power_resources_D2",
                .attrs = attrs,
        },
        [ACPI_STATE_D3_HOT] = {
                .name = "power_resources_D3hot",
                .attrs = attrs,
        },
};

static void acpi_power_hide_list(struct acpi_device *adev, int state)
{
        struct acpi_device_power_state *ps = &adev->power.states[state];
        struct acpi_power_resource_entry *entry;

        if (list_empty(&ps->resources))
                return;

        list_for_each_entry_reverse(entry, &ps->resources, node) {
                struct acpi_device *res_dev = &entry->resource->device;

                sysfs_remove_link_from_group(&adev->dev.kobj,
                                             attr_groups[state].name,
                                             dev_name(&res_dev->dev));
        }
        sysfs_remove_group(&adev->dev.kobj, &attr_groups[state]);
}

static void acpi_power_expose_list(struct acpi_device *adev, int state)
{
        struct acpi_device_power_state *ps = &adev->power.states[state];
        struct acpi_power_resource_entry *entry;
        int ret;

        if (list_empty(&ps->resources))
                return;

        ret = sysfs_create_group(&adev->dev.kobj, &attr_groups[state]);
        if (ret)
                return;

        list_for_each_entry(entry, &ps->resources, node) {
                struct acpi_device *res_dev = &entry->resource->device;

                ret = sysfs_add_link_to_group(&adev->dev.kobj,
                                              attr_groups[state].name,
                                              &res_dev->dev.kobj,
                                              dev_name(&res_dev->dev));
                if (ret) {
                        acpi_power_hide_list(adev, state);
                        break;
                }
        }
}

void acpi_power_add_remove_device(struct acpi_device *adev, bool add)
{
        struct acpi_device_power_state *ps;
        struct acpi_power_resource_entry *entry;
        int state;

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

        ps = &adev->power.states[ACPI_STATE_D0];
        list_for_each_entry(entry, &ps->resources, node) {
                struct acpi_power_resource *resource = entry->resource;

                if (add)
                        acpi_power_add_dependent(resource, adev);
                else
                        acpi_power_remove_dependent(resource, adev);
        }

        for (state = ACPI_STATE_D0; state <= ACPI_STATE_D3_HOT; state++) {
                if (add)
                        acpi_power_expose_list(adev, state);
                else
                        acpi_power_hide_list(adev, state);
        }
}

int acpi_power_wakeup_list_init(struct list_head *list, int *system_level_p)
{
        struct acpi_power_resource_entry *entry;
        int system_level = 5;

        list_for_each_entry(entry, list, node) {
                struct acpi_power_resource *resource = entry->resource;
                acpi_handle handle = resource->device.handle;
                int result;
                int state;

                mutex_lock(&resource->resource_lock);

                result = acpi_power_get_state(handle, &state);
                if (result) {
                        mutex_unlock(&resource->resource_lock);
                        return result;
                }
                if (state == ACPI_POWER_RESOURCE_STATE_ON) {
                        resource->ref_count++;
                        resource->wakeup_enabled = true;
                }
                if (system_level > resource->system_level)
                        system_level = resource->system_level;

                mutex_unlock(&resource->resource_lock);
        }
        *system_level_p = system_level;
        return 0;
}

/* --------------------------------------------------------------------------
                             Device Power Management
   -------------------------------------------------------------------------- */

/**
 * acpi_device_sleep_wake - execute _DSW (Device Sleep Wake) or (deprecated in
 *                          ACPI 3.0) _PSW (Power State Wake)
 * @dev: Device to handle.
 * @enable: 0 - disable, 1 - enable the wake capabilities of the device.
 * @sleep_state: Target sleep state of the system.
 * @dev_state: Target power state of the device.
 *
 * Execute _DSW (Device Sleep Wake) or (deprecated in ACPI 3.0) _PSW (Power
 * State Wake) for the device, if present.  On failure reset the device's
 * wakeup.flags.valid flag.
 *
 * RETURN VALUE:
 * 0 if either _DSW or _PSW has been successfully executed
 * 0 if neither _DSW nor _PSW has been found
 * -ENODEV if the execution of either _DSW or _PSW has failed
 */
int acpi_device_sleep_wake(struct acpi_device *dev,
                           int enable, int sleep_state, int dev_state)
{
        union acpi_object in_arg[3];
        struct acpi_object_list arg_list = { 3, in_arg };
        acpi_status status = AE_OK;

        /*
         * Try to execute _DSW first.
         *
         * Three agruments are needed for the _DSW object:
         * Argument 0: enable/disable the wake capabilities
         * Argument 1: target system state
         * Argument 2: target device state
         * When _DSW object is called to disable the wake capabilities, maybe
         * the first argument is filled. The values of the other two agruments
         * are meaningless.
         */
        in_arg[0].type = ACPI_TYPE_INTEGER;
        in_arg[0].integer.value = enable;
        in_arg[1].type = ACPI_TYPE_INTEGER;
        in_arg[1].integer.value = sleep_state;
        in_arg[2].type = ACPI_TYPE_INTEGER;
        in_arg[2].integer.value = dev_state;
        status = acpi_evaluate_object(dev->handle, "_DSW", &arg_list, NULL);
        if (ACPI_SUCCESS(status)) {
                return 0;
        } else if (status != AE_NOT_FOUND) {
                printk(KERN_ERR PREFIX "_DSW execution failed\n");
                dev->wakeup.flags.valid = 0;
                return -ENODEV;
        }

        /* Execute _PSW */
        arg_list.count = 1;
        in_arg[0].integer.value = enable;
        status = acpi_evaluate_object(dev->handle, "_PSW", &arg_list, NULL);
        if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
                printk(KERN_ERR PREFIX "_PSW execution failed\n");
                dev->wakeup.flags.valid = 0;
                return -ENODEV;
        }

        return 0;
}

/*
 * Prepare a wakeup device, two steps (Ref ACPI 2.0:P229):
 * 1. Power on the power resources required for the wakeup device 
 * 2. Execute _DSW (Device Sleep Wake) or (deprecated in ACPI 3.0) _PSW (Power
 *    State Wake) for the device, if present
 */
int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state)
{
        struct acpi_power_resource_entry *entry;
        int err = 0;

        if (!dev || !dev->wakeup.flags.valid)
                return -EINVAL;

        mutex_lock(&acpi_device_lock);

        if (dev->wakeup.prepare_count++)
                goto out;

        list_for_each_entry(entry, &dev->wakeup.resources, node) {
                struct acpi_power_resource *resource = entry->resource;

                mutex_lock(&resource->resource_lock);

                if (!resource->wakeup_enabled) {
                        err = acpi_power_on_unlocked(resource);
                        if (!err)
                                resource->wakeup_enabled = true;
                }

                mutex_unlock(&resource->resource_lock);

                if (err) {
                        dev_err(&dev->dev,
                                "Cannot turn wakeup power resources on\n");
                        dev->wakeup.flags.valid = 0;
                        goto out;
                }
        }
        /*
         * Passing 3 as the third argument below means the device may be
         * put into arbitrary power state afterward.
         */
        err = acpi_device_sleep_wake(dev, 1, sleep_state, 3);
        if (err)
                dev->wakeup.prepare_count = 0;

 out:
        mutex_unlock(&acpi_device_lock);
        return err;
}

/*
 * Shutdown a wakeup device, counterpart of above method
 * 1. Execute _DSW (Device Sleep Wake) or (deprecated in ACPI 3.0) _PSW (Power
 *    State Wake) for the device, if present
 * 2. Shutdown down the power resources
 */
int acpi_disable_wakeup_device_power(struct acpi_device *dev)
{
        struct acpi_power_resource_entry *entry;
        int err = 0;

        if (!dev || !dev->wakeup.flags.valid)
                return -EINVAL;

        mutex_lock(&acpi_device_lock);

        if (--dev->wakeup.prepare_count > 0)
                goto out;

        /*
         * Executing the code below even if prepare_count is already zero when
         * the function is called may be useful, for example for initialisation.
         */
        if (dev->wakeup.prepare_count < 0)
                dev->wakeup.prepare_count = 0;

        err = acpi_device_sleep_wake(dev, 0, 0, 0);
        if (err)
                goto out;

        list_for_each_entry(entry, &dev->wakeup.resources, node) {
                struct acpi_power_resource *resource = entry->resource;

                mutex_lock(&resource->resource_lock);

                if (resource->wakeup_enabled) {
                        err = acpi_power_off_unlocked(resource);
                        if (!err)
                                resource->wakeup_enabled = false;
                }

                mutex_unlock(&resource->resource_lock);

                if (err) {
                        dev_err(&dev->dev,
                                "Cannot turn wakeup power resources off\n");
                        dev->wakeup.flags.valid = 0;
                        break;
                }
        }

 out:
        mutex_unlock(&acpi_device_lock);
        return err;
}

int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
{
        int result = 0;
        int list_state = 0;
        int i = 0;

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

        /*
         * We know a device's inferred power state when all the resources
         * required for a given D-state are 'on'.
         */
        for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++) {
                struct list_head *list = &device->power.states[i].resources;

                if (list_empty(list))
                        continue;

                result = acpi_power_get_list_state(list, &list_state);
                if (result)
                        return result;

                if (list_state == ACPI_POWER_RESOURCE_STATE_ON) {
                        *state = i;
                        return 0;
                }
        }

        *state = ACPI_STATE_D3;
        return 0;
}

int acpi_power_on_resources(struct acpi_device *device, int state)
{
        if (!device || state < ACPI_STATE_D0 || state > ACPI_STATE_D3_HOT)
                return -EINVAL;

        return acpi_power_on_list(&device->power.states[state].resources);
}

int acpi_power_transition(struct acpi_device *device, int state)
{
        int result = 0;

        if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3_COLD))
                return -EINVAL;

        if (device->power.state == state || !device->flags.power_manageable)
                return 0;

        if ((device->power.state < ACPI_STATE_D0)
            || (device->power.state > ACPI_STATE_D3_COLD))
                return -ENODEV;

        /* TBD: Resources must be ordered. */

        /*
         * First we reference all power resources required in the target list
         * (e.g. so the device doesn't lose power while transitioning).  Then,
         * we dereference all power resources used in the current list.
         */
        if (state < ACPI_STATE_D3_COLD)
                result = acpi_power_on_list(
                        &device->power.states[state].resources);

        if (!result && device->power.state < ACPI_STATE_D3_COLD)
                acpi_power_off_list(
                        &device->power.states[device->power.state].resources);

        /* We shouldn't change the state unless the above operations succeed. */
        device->power.state = result ? ACPI_STATE_UNKNOWN : state;

        return result;
}

static void acpi_release_power_resource(struct device *dev)
{
        struct acpi_device *device = to_acpi_device(dev);
        struct acpi_power_resource *resource;

        resource = container_of(device, struct acpi_power_resource, device);

        mutex_lock(&power_resource_list_lock);
        list_del(&resource->list_node);
        mutex_unlock(&power_resource_list_lock);

        acpi_free_ids(device);
        kfree(resource);
}

static ssize_t acpi_power_in_use_show(struct device *dev,
                                      struct device_attribute *attr,
                                      char *buf) {
        struct acpi_power_resource *resource;

        resource = to_power_resource(to_acpi_device(dev));
        return sprintf(buf, "%u\n", !!resource->ref_count);
}
static DEVICE_ATTR(resource_in_use, 0444, acpi_power_in_use_show, NULL);

static void acpi_power_sysfs_remove(struct acpi_device *device)
{
        device_remove_file(&device->dev, &dev_attr_resource_in_use);
}

int acpi_add_power_resource(acpi_handle handle)
{
        struct acpi_power_resource *resource;
        struct acpi_device *device = NULL;
        union acpi_object acpi_object;
        struct acpi_buffer buffer = { sizeof(acpi_object), &acpi_object };
        acpi_status status;
        int state, result = -ENODEV;

        acpi_bus_get_device(handle, &device);
        if (device)
                return 0;

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

        device = &resource->device;
        acpi_init_device_object(device, handle, ACPI_BUS_TYPE_POWER,
                                ACPI_STA_DEFAULT);
        mutex_init(&resource->resource_lock);
        INIT_LIST_HEAD(&resource->dependent);
        resource->name = device->pnp.bus_id;
        strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
        strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
        device->power.state = ACPI_STATE_UNKNOWN;

        /* Evalute the object to get the system level and resource order. */
        status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
        if (ACPI_FAILURE(status))
                goto err;

        resource->system_level = acpi_object.power_resource.system_level;
        resource->order = acpi_object.power_resource.resource_order;

        result = acpi_power_get_state(handle, &state);
        if (result)
                goto err;

        printk(KERN_INFO PREFIX "%s [%s] (%s)\n", acpi_device_name(device),
               acpi_device_bid(device), state ? "on" : "off");

        device->flags.match_driver = true;
        result = acpi_device_add(device, acpi_release_power_resource);
        if (result)
                goto err;

        if (!device_create_file(&device->dev, &dev_attr_resource_in_use))
                device->remove = acpi_power_sysfs_remove;

        mutex_lock(&power_resource_list_lock);
        list_add(&resource->list_node, &acpi_power_resource_list);
        mutex_unlock(&power_resource_list_lock);
        acpi_device_add_finalize(device);
        return 0;

 err:
        acpi_release_power_resource(&device->dev);
        return result;
}

#ifdef CONFIG_ACPI_SLEEP
void acpi_resume_power_resources(void)
{
        struct acpi_power_resource *resource;

        mutex_lock(&power_resource_list_lock);

        list_for_each_entry(resource, &acpi_power_resource_list, list_node) {
                int result, state;

                mutex_lock(&resource->resource_lock);

                result = acpi_power_get_state(resource->device.handle, &state);
                if (result)
                        continue;

                if (state == ACPI_POWER_RESOURCE_STATE_OFF
                    && resource->ref_count) {
                        dev_info(&resource->device.dev, "Turning ON\n");
                        __acpi_power_on(resource);
                } else if (state == ACPI_POWER_RESOURCE_STATE_ON
                    && !resource->ref_count) {
                        dev_info(&resource->device.dev, "Turning OFF\n");
                        __acpi_power_off(resource);
                }

                mutex_unlock(&resource->resource_lock);
        }

        mutex_unlock(&power_resource_list_lock);
}
#endif