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 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * drivers/acpi/power.c - ACPI Power Resources management.
  *
  * Copyright (C) 2001 - 2015 Intel Corp.
  * Author: Andy Grover <andrew.grover@intel.com>
  * Author: Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
  * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  */
 
 /*
  * ACPI power-managed devices may be controlled in two ways:
  * 1. via "Device Specific (D-State) Control"
  * 2. via "Power Resource Control".
  * The code below deals with ACPI Power Resources control.
  *
  * An ACPI "power resource object" represents a software controllable power
  * plane, clock plane, or other resource depended on by a device.
  *
  * A device may rely on multiple power resources, and a power resource
  * may be shared by multiple devices.
  */
 
 #define pr_fmt(fmt) "ACPI: PM: " fmt
 
 #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 <linux/acpi.h>
 #include "sleep.h"
 #include "internal.h"
 
 #define ACPI_POWER_CLASS        "power_resource"
 #define ACPI_POWER_DEVICE_NAME      "Power Resource"
 #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 device *dev;
     struct list_head node;
 };
 
 struct acpi_power_resource {
     struct acpi_device device;
     struct list_head list_node;
     u32 system_level;
     u32 order;
     unsigned int ref_count;
     u8 state;
     struct mutex resource_lock;
     struct list_head dependents;
 };
 
 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 const char *resource_dev_name(struct acpi_power_resource *pr)
 {
     return dev_name(&pr->device.dev);
 }
 
 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 = acpi_fetch_acpi_dev(handle);
 
     if (!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);
     }
 }
 
 static bool acpi_power_resource_is_dup(union acpi_object *package,
                        unsigned int start, unsigned int i)
 {
     acpi_handle rhandle, dup;
     unsigned int j;
 
     /* The caller is expected to check the package element types */
     rhandle = package->package.elements[i].reference.handle;
     for (j = start; j < i; j++) {
         dup = package->package.elements[j].reference.handle;
         if (dup == rhandle)
             return true;
     }
 
     return false;
 }
 
 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];
         struct acpi_device *rdev;
         acpi_handle rhandle;
 
         if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
             err = -ENODATA;
             break;
         }
         rhandle = element->reference.handle;
         if (!rhandle) {
             err = -ENODEV;
             break;
         }
 
         /* Some ACPI tables contain duplicate power resource references */
         if (acpi_power_resource_is_dup(package, start, i))
             continue;
 
         rdev = acpi_add_power_resource(rhandle);
         if (!rdev) {
             err = -ENODEV;
             break;
         }
         err = acpi_power_resources_list_add(rhandle, list);
         if (err)
             break;
     }
     if (err)
         acpi_power_resources_list_free(list);
 
     return err;
 }
 
 static int __get_state(acpi_handle handle, u8 *state)
 {
     acpi_status status = AE_OK;
     unsigned long long sta = 0;
     u8 cur_state;
 
     status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
     if (ACPI_FAILURE(status))
         return -ENODEV;
 
     cur_state = sta & ACPI_POWER_RESOURCE_STATE_ON;
 
     acpi_handle_debug(handle, "Power resource is %s\n",
               cur_state ? "on" : "off");
 
     *state = cur_state;
     return 0;
 }
 
 static int acpi_power_get_state(struct acpi_power_resource *resource, u8 *state)
 {
     if (resource->state == ACPI_POWER_RESOURCE_STATE_UNKNOWN) {
         int ret;
 
         ret = __get_state(resource->device.handle, &resource->state);
         if (ret)
             return ret;
     }
 
     *state = resource->state;
     return 0;
 }
 
 static int acpi_power_get_list_state(struct list_head *list, u8 *state)
 {
     struct acpi_power_resource_entry *entry;
     u8 cur_state = ACPI_POWER_RESOURCE_STATE_OFF;
 
     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;
         int result;
 
         mutex_lock(&resource->resource_lock);
         result = acpi_power_get_state(resource, &cur_state);
         mutex_unlock(&resource->resource_lock);
         if (result)
             return result;
 
         if (cur_state != ACPI_POWER_RESOURCE_STATE_ON)
             break;
     }
 
     pr_debug("Power resource list is %s\n", cur_state ? "on" : "off");
 
     *state = cur_state;
     return 0;
 }
 
 static int
 acpi_power_resource_add_dependent(struct acpi_power_resource *resource,
                   struct device *dev)
 {
     struct acpi_power_dependent_device *dep;
     int ret = 0;
 
     mutex_lock(&resource->resource_lock);
     list_for_each_entry(dep, &resource->dependents, node) {
         /* Only add it once */
         if (dep->dev == dev)
             goto unlock;
     }
 
     dep = kzalloc(sizeof(*dep), GFP_KERNEL);
     if (!dep) {
         ret = -ENOMEM;
         goto unlock;
     }
 
     dep->dev = dev;
     list_add_tail(&dep->node, &resource->dependents);
     dev_dbg(dev, "added power dependency to [%s]\n",
         resource_dev_name(resource));
 
 unlock:
     mutex_unlock(&resource->resource_lock);
     return ret;
 }
 
 static void
 acpi_power_resource_remove_dependent(struct acpi_power_resource *resource,
                      struct device *dev)
 {
     struct acpi_power_dependent_device *dep;
 
     mutex_lock(&resource->resource_lock);
     list_for_each_entry(dep, &resource->dependents, node) {
         if (dep->dev == dev) {
             list_del(&dep->node);
             kfree(dep);
             dev_dbg(dev, "removed power dependency to [%s]\n",
                 resource_dev_name(resource));
             break;
         }
     }
     mutex_unlock(&resource->resource_lock);
 }
 
 /**
  * acpi_device_power_add_dependent - Add dependent device of this ACPI device
  * @adev: ACPI device pointer
  * @dev: Dependent device
  *
  * If @adev has non-empty _PR0 the @dev is added as dependent device to all
  * power resources returned by it. This means that whenever these power
  * resources are turned _ON the dependent devices get runtime resumed. This
  * is needed for devices such as PCI to allow its driver to re-initialize
  * it after it went to D0uninitialized.
  *
  * If @adev does not have _PR0 this does nothing.
  *
  * Returns %0 in case of success and negative errno otherwise.
  */
 int acpi_device_power_add_dependent(struct acpi_device *adev,
                     struct device *dev)
 {
     struct acpi_power_resource_entry *entry;
     struct list_head *resources;
     int ret;
 
     if (!adev->flags.power_manageable)
         return 0;
 
     resources = &adev->power.states[ACPI_STATE_D0].resources;
     list_for_each_entry(entry, resources, node) {
         ret = acpi_power_resource_add_dependent(entry->resource, dev);
         if (ret)
             goto err;
     }
 
     return 0;
 
 err:
     list_for_each_entry(entry, resources, node)
         acpi_power_resource_remove_dependent(entry->resource, dev);
 
     return ret;
 }
 
 /**
  * acpi_device_power_remove_dependent - Remove dependent device
  * @adev: ACPI device pointer
  * @dev: Dependent device
  *
  * Does the opposite of acpi_device_power_add_dependent() and removes the
  * dependent device if it is found. Can be called to @adev that does not
  * have _PR0 as well.
  */
 void acpi_device_power_remove_dependent(struct acpi_device *adev,
                     struct device *dev)
 {
     struct acpi_power_resource_entry *entry;
     struct list_head *resources;
 
     if (!adev->flags.power_manageable)
         return;
 
     resources = &adev->power.states[ACPI_STATE_D0].resources;
     list_for_each_entry_reverse(entry, resources, node)
         acpi_power_resource_remove_dependent(entry->resource, dev);
 }
 
 static int __acpi_power_on(struct acpi_power_resource *resource)
 {
     acpi_handle handle = resource->device.handle;
     struct acpi_power_dependent_device *dep;
     acpi_status status = AE_OK;
 
     status = acpi_evaluate_object(handle, "_ON", NULL, NULL);
     if (ACPI_FAILURE(status)) {
         resource->state = ACPI_POWER_RESOURCE_STATE_UNKNOWN;
         return -ENODEV;
     }
 
     resource->state = ACPI_POWER_RESOURCE_STATE_ON;
 
     acpi_handle_debug(handle, "Power resource turned on\n");
 
     /*
      * If there are other dependents on this power resource we need to
      * resume them now so that their drivers can re-initialize the
      * hardware properly after it went back to D0.
      */
     if (list_empty(&resource->dependents) ||
         list_is_singular(&resource->dependents))
         return 0;
 
     list_for_each_entry(dep, &resource->dependents, node) {
         dev_dbg(dep->dev, "runtime resuming because [%s] turned on\n",
             resource_dev_name(resource));
         pm_request_resume(dep->dev);
     }
 
     return 0;
 }
 
 static int acpi_power_on_unlocked(struct acpi_power_resource *resource)
 {
     int result = 0;
 
     if (resource->ref_count++) {
         acpi_handle_debug(resource->device.handle,
                   "Power resource already on\n");
     } else {
         result = __acpi_power_on(resource);
         if (result)
             resource->ref_count--;
     }
     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_handle handle = resource->device.handle;
     acpi_status status;
 
     status = acpi_evaluate_object(handle, "_OFF", NULL, NULL);
     if (ACPI_FAILURE(status)) {
         resource->state = ACPI_POWER_RESOURCE_STATE_UNKNOWN;
         return -ENODEV;
     }
 
     resource->state = ACPI_POWER_RESOURCE_STATE_OFF;
 
     acpi_handle_debug(handle, "Power resource turned off\n");
 
     return 0;
 }
 
 static int acpi_power_off_unlocked(struct acpi_power_resource *resource)
 {
     int result = 0;
 
     if (!resource->ref_count) {
         acpi_handle_debug(resource->device.handle,
                   "Power resource already off\n");
         return 0;
     }
 
     if (--resource->ref_count) {
         acpi_handle_debug(resource->device.handle,
                   "Power resource still in use\n");
     } 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 struct attribute *attrs[] = {
     NULL,
 };
 
 static const 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 const struct attribute_group wakeup_attr_group = {
     .name = "power_resources_wakeup",
     .attrs = attrs,
 };
 
 static void acpi_power_hide_list(struct acpi_device *adev,
                  struct list_head *resources,
                  const struct attribute_group *attr_group)
 {
     struct acpi_power_resource_entry *entry;
 
     if (list_empty(resources))
         return;
 
     list_for_each_entry_reverse(entry, resources, node) {
         struct acpi_device *res_dev = &entry->resource->device;
 
         sysfs_remove_link_from_group(&adev->dev.kobj,
                          attr_group->name,
                          dev_name(&res_dev->dev));
     }
     sysfs_remove_group(&adev->dev.kobj, attr_group);
 }
 
 static void acpi_power_expose_list(struct acpi_device *adev,
                    struct list_head *resources,
                    const struct attribute_group *attr_group)
 {
     struct acpi_power_resource_entry *entry;
     int ret;
 
     if (list_empty(resources))
         return;
 
     ret = sysfs_create_group(&adev->dev.kobj, attr_group);
     if (ret)
         return;
 
     list_for_each_entry(entry, resources, node) {
         struct acpi_device *res_dev = &entry->resource->device;
 
         ret = sysfs_add_link_to_group(&adev->dev.kobj,
                           attr_group->name,
                           &res_dev->dev.kobj,
                           dev_name(&res_dev->dev));
         if (ret) {
             acpi_power_hide_list(adev, resources, attr_group);
             break;
         }
     }
 }
 
 static void acpi_power_expose_hide(struct acpi_device *adev,
                    struct list_head *resources,
                    const struct attribute_group *attr_group,
                    bool expose)
 {
     if (expose)
         acpi_power_expose_list(adev, resources, attr_group);
     else
         acpi_power_hide_list(adev, resources, attr_group);
 }
 
 void acpi_power_add_remove_device(struct acpi_device *adev, bool add)
 {
     int state;
 
     if (adev->wakeup.flags.valid)
         acpi_power_expose_hide(adev, &adev->wakeup.resources,
                        &wakeup_attr_group, add);
 
     if (!adev->power.flags.power_resources)
         return;
 
     for (state = ACPI_STATE_D0; state <= ACPI_STATE_D3_HOT; state++)
         acpi_power_expose_hide(adev,
                        &adev->power.states[state].resources,
                        &attr_groups[state], add);
 }
 
 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;
         u8 state;
 
         mutex_lock(&resource->resource_lock);
 
         /*
          * Make sure that the power resource state and its reference
          * counter value are consistent with each other.
          */
         if (!resource->ref_count &&
             !acpi_power_get_state(resource, &state) &&
             state == ACPI_POWER_RESOURCE_STATE_ON)
             __acpi_power_off(resource);
 
         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 arguments 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 arguments
      * 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) {
         acpi_handle_info(dev->handle, "_DSW execution failed\n");
         dev->wakeup.flags.valid = 0;
         return -ENODEV;
     }
 
     /* Execute _PSW */
     status = acpi_execute_simple_method(dev->handle, "_PSW", enable);
     if (ACPI_FAILURE(status) && (status != AE_NOT_FOUND)) {
         acpi_handle_info(dev->handle, "_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)
 {
     int err = 0;
 
     if (!dev || !dev->wakeup.flags.valid)
         return -EINVAL;
 
     mutex_lock(&acpi_device_lock);
 
     dev_dbg(&dev->dev, "Enabling wakeup power (count %d)\n",
         dev->wakeup.prepare_count);
 
     if (dev->wakeup.prepare_count++)
         goto out;
 
     err = acpi_power_on_list(&dev->wakeup.resources);
     if (err) {
         dev_err(&dev->dev, "Cannot turn on wakeup power resources\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) {
         acpi_power_off_list(&dev->wakeup.resources);
         dev->wakeup.prepare_count = 0;
         goto out;
     }
 
     dev_dbg(&dev->dev, "Wakeup power enabled\n");
 
  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);
 
     dev_dbg(&dev->dev, "Disabling wakeup power (count %d)\n",
         dev->wakeup.prepare_count);
 
     /* Do nothing if wakeup power has not been enabled for this device. */
     if (dev->wakeup.prepare_count <= 0)
         goto out;
 
     if (--dev->wakeup.prepare_count > 0)
         goto out;
 
     err = acpi_device_sleep_wake(dev, 0, 0, 0);
     if (err)
         goto out;
 
     /*
      * All of the power resources in the list need to be turned off even if
      * there are errors.
      */
     list_for_each_entry(entry, &dev->wakeup.resources, node) {
         int ret;
 
         ret = acpi_power_off(entry->resource);
         if (ret && !err)
             err = ret;
     }
     if (err) {
         dev_err(&dev->dev, "Cannot turn off wakeup power resources\n");
         dev->wakeup.flags.valid = 0;
         goto out;
     }
 
     dev_dbg(&dev->dev, "Wakeup power disabled\n");
 
  out:
     mutex_unlock(&acpi_device_lock);
     return err;
 }
 
 int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
 {
     u8 list_state = ACPI_POWER_RESOURCE_STATE_OFF;
     int result = 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 = device->power.states[ACPI_STATE_D3_COLD].flags.valid ?
         ACPI_STATE_D3_COLD : ACPI_STATE_D3_HOT;
     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;
 
     /*
      * 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_pnp_ids(&device->pnp);
     kfree(resource);
 }
 
 static ssize_t resource_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_RO(resource_in_use);
 
 static void acpi_power_sysfs_remove(struct acpi_device *device)
 {
     device_remove_file(&device->dev, &dev_attr_resource_in_use);
 }
 
 static void acpi_power_add_resource_to_list(struct acpi_power_resource *resource)
 {
     mutex_lock(&power_resource_list_lock);
 
     if (!list_empty(&acpi_power_resource_list)) {
         struct acpi_power_resource *r;
 
         list_for_each_entry(r, &acpi_power_resource_list, list_node)
             if (r->order > resource->order) {
                 list_add_tail(&resource->list_node, &r->list_node);
                 goto out;
             }
     }
     list_add_tail(&resource->list_node, &acpi_power_resource_list);
 
  out:
     mutex_unlock(&power_resource_list_lock);
 }
 
 struct acpi_device *acpi_add_power_resource(acpi_handle handle)
 {
     struct acpi_device *device = acpi_fetch_acpi_dev(handle);
     struct acpi_power_resource *resource;
     union acpi_object acpi_object;
     struct acpi_buffer buffer = { sizeof(acpi_object), &acpi_object };
     acpi_status status;
     u8 state_dummy;
     int result;
 
     if (device)
         return device;
 
     resource = kzalloc(sizeof(*resource), GFP_KERNEL);
     if (!resource)
         return NULL;
 
     device = &resource->device;
     acpi_init_device_object(device, handle, ACPI_BUS_TYPE_POWER);
     mutex_init(&resource->resource_lock);
     INIT_LIST_HEAD(&resource->list_node);
     INIT_LIST_HEAD(&resource->dependents);
     strcpy(acpi_device_name(device), ACPI_POWER_DEVICE_NAME);
     strcpy(acpi_device_class(device), ACPI_POWER_CLASS);
     device->power.state = ACPI_STATE_UNKNOWN;
 
     /* Evaluate 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;
     resource->state = ACPI_POWER_RESOURCE_STATE_UNKNOWN;
 
     /* Get the initial state or just flip it on if that fails. */
     if (acpi_power_get_state(resource, &state_dummy))
         __acpi_power_on(resource);
 
     pr_info("%s [%s]\n", acpi_device_name(device), acpi_device_bid(device));
 
     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;
 
     acpi_power_add_resource_to_list(resource);
     acpi_device_add_finalize(device);
     return device;
 
  err:
     acpi_release_power_resource(&device->dev);
     return NULL;
 }
 
 #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;
         u8 state;
 
         mutex_lock(&resource->resource_lock);
 
         resource->state = ACPI_POWER_RESOURCE_STATE_UNKNOWN;
         result = acpi_power_get_state(resource, &state);
         if (result) {
             mutex_unlock(&resource->resource_lock);
             continue;
         }
 
         if (state == ACPI_POWER_RESOURCE_STATE_OFF
             && resource->ref_count) {
             acpi_handle_debug(resource->device.handle, "Turning ON\n");
             __acpi_power_on(resource);
         }
 
         mutex_unlock(&resource->resource_lock);
     }
 
     mutex_unlock(&power_resource_list_lock);
 }
 #endif
 
 /**
  * acpi_turn_off_unused_power_resources - Turn off power resources not in use.
  */
 void acpi_turn_off_unused_power_resources(void)
 {
     struct acpi_power_resource *resource;
 
     mutex_lock(&power_resource_list_lock);
 
     list_for_each_entry_reverse(resource, &acpi_power_resource_list, list_node) {
         mutex_lock(&resource->resource_lock);
 
         if (!resource->ref_count &&
             resource->state == ACPI_POWER_RESOURCE_STATE_ON) {
             acpi_handle_debug(resource->device.handle, "Turning OFF\n");
             __acpi_power_off(resource);
         }
 
         mutex_unlock(&resource->resource_lock);
     }
 
     mutex_unlock(&power_resource_list_lock);
 }

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