linux/drivers/base/power/common.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * drivers/base/power/common.c - Common device power management code.
   4 *
   5 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
   6 */
   7#include <linux/kernel.h>
   8#include <linux/device.h>
   9#include <linux/export.h>
  10#include <linux/slab.h>
  11#include <linux/pm_clock.h>
  12#include <linux/acpi.h>
  13#include <linux/pm_domain.h>
  14
  15#include "power.h"
  16
  17/**
  18 * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
  19 * @dev: Device to handle.
  20 *
  21 * If power.subsys_data is NULL, point it to a new object, otherwise increment
  22 * its reference counter.  Return 0 if new object has been created or refcount
  23 * increased, otherwise negative error code.
  24 */
  25int dev_pm_get_subsys_data(struct device *dev)
  26{
  27        struct pm_subsys_data *psd;
  28
  29        psd = kzalloc(sizeof(*psd), GFP_KERNEL);
  30        if (!psd)
  31                return -ENOMEM;
  32
  33        spin_lock_irq(&dev->power.lock);
  34
  35        if (dev->power.subsys_data) {
  36                dev->power.subsys_data->refcount++;
  37        } else {
  38                spin_lock_init(&psd->lock);
  39                psd->refcount = 1;
  40                dev->power.subsys_data = psd;
  41                pm_clk_init(dev);
  42                psd = NULL;
  43        }
  44
  45        spin_unlock_irq(&dev->power.lock);
  46
  47        /* kfree() verifies that its argument is nonzero. */
  48        kfree(psd);
  49
  50        return 0;
  51}
  52EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
  53
  54/**
  55 * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
  56 * @dev: Device to handle.
  57 *
  58 * If the reference counter of power.subsys_data is zero after dropping the
  59 * reference, power.subsys_data is removed.
  60 */
  61void dev_pm_put_subsys_data(struct device *dev)
  62{
  63        struct pm_subsys_data *psd;
  64
  65        spin_lock_irq(&dev->power.lock);
  66
  67        psd = dev_to_psd(dev);
  68        if (!psd)
  69                goto out;
  70
  71        if (--psd->refcount == 0)
  72                dev->power.subsys_data = NULL;
  73        else
  74                psd = NULL;
  75
  76 out:
  77        spin_unlock_irq(&dev->power.lock);
  78        kfree(psd);
  79}
  80EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
  81
  82/**
  83 * dev_pm_domain_attach - Attach a device to its PM domain.
  84 * @dev: Device to attach.
  85 * @power_on: Used to indicate whether we should power on the device.
  86 *
  87 * The @dev may only be attached to a single PM domain. By iterating through
  88 * the available alternatives we try to find a valid PM domain for the device.
  89 * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
  90 * should be assigned by the corresponding attach function.
  91 *
  92 * This function should typically be invoked from subsystem level code during
  93 * the probe phase. Especially for those that holds devices which requires
  94 * power management through PM domains.
  95 *
  96 * Callers must ensure proper synchronization of this function with power
  97 * management callbacks.
  98 *
  99 * Returns 0 on successfully attached PM domain, or when it is found that the
 100 * device doesn't need a PM domain, else a negative error code.
 101 */
 102int dev_pm_domain_attach(struct device *dev, bool power_on)
 103{
 104        int ret;
 105
 106        if (dev->pm_domain)
 107                return 0;
 108
 109        ret = acpi_dev_pm_attach(dev, power_on);
 110        if (!ret)
 111                ret = genpd_dev_pm_attach(dev);
 112
 113        return ret < 0 ? ret : 0;
 114}
 115EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
 116
 117/**
 118 * dev_pm_domain_attach_by_id - Associate a device with one of its PM domains.
 119 * @dev: The device used to lookup the PM domain.
 120 * @index: The index of the PM domain.
 121 *
 122 * As @dev may only be attached to a single PM domain, the backend PM domain
 123 * provider creates a virtual device to attach instead. If attachment succeeds,
 124 * the ->detach() callback in the struct dev_pm_domain are assigned by the
 125 * corresponding backend attach function, as to deal with detaching of the
 126 * created virtual device.
 127 *
 128 * This function should typically be invoked by a driver during the probe phase,
 129 * in case its device requires power management through multiple PM domains. The
 130 * driver may benefit from using the received device, to configure device-links
 131 * towards its original device. Depending on the use-case and if needed, the
 132 * links may be dynamically changed by the driver, which allows it to control
 133 * the power to the PM domains independently from each other.
 134 *
 135 * Callers must ensure proper synchronization of this function with power
 136 * management callbacks.
 137 *
 138 * Returns the virtual created device when successfully attached to its PM
 139 * domain, NULL in case @dev don't need a PM domain, else an ERR_PTR().
 140 * Note that, to detach the returned virtual device, the driver shall call
 141 * dev_pm_domain_detach() on it, typically during the remove phase.
 142 */
 143struct device *dev_pm_domain_attach_by_id(struct device *dev,
 144                                          unsigned int index)
 145{
 146        if (dev->pm_domain)
 147                return ERR_PTR(-EEXIST);
 148
 149        return genpd_dev_pm_attach_by_id(dev, index);
 150}
 151EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_id);
 152
 153/**
 154 * dev_pm_domain_attach_by_name - Associate a device with one of its PM domains.
 155 * @dev: The device used to lookup the PM domain.
 156 * @name: The name of the PM domain.
 157 *
 158 * For a detailed function description, see dev_pm_domain_attach_by_id().
 159 */
 160struct device *dev_pm_domain_attach_by_name(struct device *dev,
 161                                            const char *name)
 162{
 163        if (dev->pm_domain)
 164                return ERR_PTR(-EEXIST);
 165
 166        return genpd_dev_pm_attach_by_name(dev, name);
 167}
 168EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_name);
 169
 170/**
 171 * dev_pm_domain_detach - Detach a device from its PM domain.
 172 * @dev: Device to detach.
 173 * @power_off: Used to indicate whether we should power off the device.
 174 *
 175 * This functions will reverse the actions from dev_pm_domain_attach() and
 176 * dev_pm_domain_attach_by_id(), thus it detaches @dev from its PM domain.
 177 * Typically it should be invoked during the remove phase, either from
 178 * subsystem level code or from drivers.
 179 *
 180 * Callers must ensure proper synchronization of this function with power
 181 * management callbacks.
 182 */
 183void dev_pm_domain_detach(struct device *dev, bool power_off)
 184{
 185        if (dev->pm_domain && dev->pm_domain->detach)
 186                dev->pm_domain->detach(dev, power_off);
 187}
 188EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
 189
 190/**
 191 * dev_pm_domain_set - Set PM domain of a device.
 192 * @dev: Device whose PM domain is to be set.
 193 * @pd: PM domain to be set, or NULL.
 194 *
 195 * Sets the PM domain the device belongs to. The PM domain of a device needs
 196 * to be set before its probe finishes (it's bound to a driver).
 197 *
 198 * This function must be called with the device lock held.
 199 */
 200void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
 201{
 202        if (dev->pm_domain == pd)
 203                return;
 204
 205        WARN(pd && device_is_bound(dev),
 206             "PM domains can only be changed for unbound devices\n");
 207        dev->pm_domain = pd;
 208        device_pm_check_callbacks(dev);
 209}
 210EXPORT_SYMBOL_GPL(dev_pm_domain_set);
 211