device_pm.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/acpi/device_pm.c - ACPI device power management routines.
 *
 * Copyright (C) 2012, Intel Corp.
 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/acpi.h>
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/pm_qos.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/suspend.h>

#include "internal.h"

#define _COMPONENT	ACPI_POWER_COMPONENT
ACPI_MODULE_NAME("device_pm");

/**
 * acpi_power_state_string - String representation of ACPI device power state.
 * @state: ACPI device power state to return the string representation of.
 */
const char *acpi_power_state_string(int state)
{
	switch (state) {
	case ACPI_STATE_D0:
		return "D0";
	case ACPI_STATE_D1:
		return "D1";
	case ACPI_STATE_D2:
		return "D2";
	case ACPI_STATE_D3_HOT:
		return "D3hot";
	case ACPI_STATE_D3_COLD:
		return "D3cold";
	default:
		return "(unknown)";
	}
}

static int acpi_dev_pm_explicit_get(struct acpi_device *device, int *state)
{
	unsigned long long psc;
	acpi_status status;

	status = acpi_evaluate_integer(device->handle, "_PSC", NULL, &psc);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	*state = psc;
	return 0;
}

/**
 * acpi_device_get_power - Get power state of an ACPI device.
 * @device: Device to get the power state of.
 * @state: Place to store the power state of the device.
 *
 * This function does not update the device's power.state field, but it may
 * update its parent's power.state field (when the parent's power state is
 * unknown and the device's power state turns out to be D0).
 *
 * Also, it does not update power resource reference counters to ensure that