drivers/base/power/common.c

   1 /*
   2  * drivers/base/power/common.c - Common device power management code.
   3  *
   4  * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
   5  *
   6  * This file is released under the GPLv2.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/device.h>
  11 #include <linux/export.h>
  12 #include <linux/slab.h>
  13 #include <linux/pm_clock.h>
  14 #include <linux/acpi.h>
  15 #include <linux/pm_domain.h>
  16
  17 #include "power.h"
  18
  19 /**
  20  * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
  21  * @dev: Device to handle.
  22  *
  23  * If power.subsys_data is NULL, point it to a new object, otherwise increment
  24  * its reference counter.  Return 0 if new object has been created or refcount
  25  * increased, otherwise negative error code.
  26  */
  27 int dev_pm_get_subsys_data(struct device *dev)
  28 {
  29         struct pm_subsys_data *psd;
  30
  31         psd = kzalloc(sizeof(*psd), GFP_KERNEL);
  32         if (!psd)
  33                 return -ENOMEM;
  34
  35         spin_lock_irq(&dev->power.lock);
  36
  37         if (dev->power.subsys_data) {
  38                 dev->power.subsys_data->refcount++;
  39         } else {
  40                 spin_lock_init(&psd->lock);
  41                 psd->refcount = 1;
  42                 dev->power.subsys_data = psd;
  43                 pm_clk_init(dev);
  44                 psd = NULL;
  45         }
  46
  47         spin_unlock_irq(&dev->power.lock);
  48
  49         /* kfree() verifies that its argument is nonzero. */
  50         kfree(psd);
  51
  52         return 0;
  53 }
  54 EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
  55
  56 /**
  57  * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
  58  * @dev: Device to handle.
  59  *
  60  * If the reference counter of power.subsys_data is zero after dropping the
  61  * reference, power.subsys_data is removed.
  62  */
  63 void dev_pm_put_subsys_data(struct device *dev)
  64 {
  65         struct pm_subsys_data *psd;
  66
  67         spin_lock_irq(&dev->power.lock);
  68
  69         psd = dev_to_psd(dev);
  70         if (!psd)
  71                 goto out;
  72
  73         if (--psd->refcount == 0)
  74                 dev->power.subsys_data = NULL;
  75         else
  76                 psd = NULL;
  77
  78  out:
  79         spin_unlock_irq(&dev->power.lock);
  80         kfree(psd);
  81 }
  82 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
  83
  84 /**
  85  * dev_pm_domain_attach - Attach a device to its PM domain.
  86  * @dev: Device to attach.
  87  * @power_on: Used to indicate whether we should power on the device.
  88  *
  89  * The @dev may only be attached to a single PM domain. By iterating through
  90  * the available alternatives we try to find a valid PM domain for the device.
  91  * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
  92  * should be assigned by the corresponding attach function.
  93  *
  94  * This function should typically be invoked from subsystem level code during
  95  * the probe phase. Especially for those that holds devices which requires
  96  * power management through PM domains.
  97  *
  98  * Callers must ensure proper synchronization of this function with power
  99  * management callbacks.
 100  *
 101  * Returns 0 on successfully attached PM domain, or when it is found that the
 102  * device doesn't need a PM domain, else a negative error code.
 103  */
 104 int dev_pm_domain_attach(struct device *dev, bool power_on)
 105 {
 106         int ret;
 107
 108         if (dev->pm_domain)
 109                 return 0;
 110
 111         ret = acpi_dev_pm_attach(dev, power_on);
 112         if (!ret)
 113                 ret = genpd_dev_pm_attach(dev);
 114
 115         return ret < 0 ? ret : 0;
 116 }
 117 EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
 118
 119 /**
 120  * dev_pm_domain_attach_by_id - Associate a device with one of its PM domains.
 121  * @dev: The device used to lookup the PM domain.
 122  * @index: The index of the PM domain.
 123  *
 124  * As @dev may only be attached to a single PM domain, the backend PM domain
 125  * provider creates a virtual device to attach instead. If attachment succeeds,
 126  * the ->detach() callback in the struct dev_pm_domain are assigned by the
 127  * corresponding backend attach function, as to deal with detaching of the
 128  * created virtual device.
 129  *
 130  * This function should typically be invoked by a driver during the probe phase,
 131  * in case its device requires power management through multiple PM domains. The
 132  * driver may benefit from using the received device, to configure device-links
 133  * towards its original device. Depending on the use-case and if needed, the
 134  * links may be dynamically changed by the driver, which allows it to control
 135  * the power to the PM domains independently from each other.
 136  *
 137  * Callers must ensure proper synchronization of this function with power
 138  * management callbacks.
 139  *
 140  * Returns the virtual created device when successfully attached to its PM
 141  * domain, NULL in case @dev don't need a PM domain, else an ERR_PTR().
 142  * Note that, to detach the returned virtual device, the driver shall call
 143  * dev_pm_domain_detach() on it, typically during the remove phase.
 144  */
 145 struct device *dev_pm_domain_attach_by_id(struct device *dev,
 146                                           unsigned int index)
 147 {
 148         if (dev->pm_domain)
 149                 return ERR_PTR(-EEXIST);
 150
 151         return genpd_dev_pm_attach_by_id(dev, index);
 152 }
 153 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_id);
 154
 155 /**
 156  * dev_pm_domain_attach_by_name - Associate a device with one of its PM domains.
 157  * @dev: The device used to lookup the PM domain.
 158  * @name: The name of the PM domain.
 159  *
 160  * For a detailed function description, see dev_pm_domain_attach_by_id().
 161  */
 162 struct device *dev_pm_domain_attach_by_name(struct device *dev,
 163                                             const char *name)
 164 {
 165         if (dev->pm_domain)
 166                 return ERR_PTR(-EEXIST);
 167
 168         return genpd_dev_pm_attach_by_name(dev, name);
 169 }
 170 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_name);
 171
 172 /**
 173  * dev_pm_domain_detach - Detach a device from its PM domain.
 174  * @dev: Device to detach.
 175  * @power_off: Used to indicate whether we should power off the device.
 176  *
 177  * This functions will reverse the actions from dev_pm_domain_attach() and
 178  * dev_pm_domain_attach_by_id(), thus it detaches @dev from its PM domain.
 179  * Typically it should be invoked during the remove phase, either from
 180  * subsystem level code or from drivers.
 181  *
 182  * Callers must ensure proper synchronization of this function with power
 183  * management callbacks.
 184  */
 185 void dev_pm_domain_detach(struct device *dev, bool power_off)
 186 {
 187         if (dev->pm_domain && dev->pm_domain->detach)
 188                 dev->pm_domain->detach(dev, power_off);
 189 }
 190 EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
 191
 192 /**
 193  * dev_pm_domain_set - Set PM domain of a device.
 194  * @dev: Device whose PM domain is to be set.
 195  * @pd: PM domain to be set, or NULL.
 196  *
 197  * Sets the PM domain the device belongs to. The PM domain of a device needs
 198  * to be set before its probe finishes (it's bound to a driver).
 199  *
 200  * This function must be called with the device lock held.
 201  */
 202 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
 203 {
 204         if (dev->pm_domain == pd)
 205                 return;
 206
 207         WARN(pd && device_is_bound(dev),
 208              "PM domains can only be changed for unbound devices\n");
 209         dev->pm_domain = pd;
 210         device_pm_check_callbacks(dev);
 211 }
 212 EXPORT_SYMBOL_GPL(dev_pm_domain_set);