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 negative error code.
 102  */
 103 int dev_pm_domain_attach(struct device *dev, bool power_on)
 104 {
 105         int ret;
 106
 107         ret = acpi_dev_pm_attach(dev, power_on);
 108         if (ret)
 109                 ret = genpd_dev_pm_attach(dev);
 110
 111         return ret;
 112 }
 113 EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
 114
 115 /**
 116  * dev_pm_domain_detach - Detach a device from its PM domain.
 117  * @dev: Device to detach.
 118  * @power_off: Used to indicate whether we should power off the device.
 119  *
 120  * This functions will reverse the actions from dev_pm_domain_attach() and thus
 121  * try to detach the @dev from its PM domain. Typically it should be invoked
 122  * from subsystem level code during the remove phase.
 123  *
 124  * Callers must ensure proper synchronization of this function with power
 125  * management callbacks.
 126  */
 127 void dev_pm_domain_detach(struct device *dev, bool power_off)
 128 {
 129         if (dev->pm_domain && dev->pm_domain->detach)
 130                 dev->pm_domain->detach(dev, power_off);
 131 }
 132 EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
 133
 134 /**
 135  * dev_pm_domain_set - Set PM domain of a device.
 136  * @dev: Device whose PM domain is to be set.
 137  * @pd: PM domain to be set, or NULL.
 138  *
 139  * Sets the PM domain the device belongs to. The PM domain of a device needs
 140  * to be set before its probe finishes (it's bound to a driver).
 141  *
 142  * This function must be called with the device lock held.
 143  */
 144 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
 145 {
 146         if (dev->pm_domain == pd)
 147                 return;
 148
 149         WARN(pd && device_is_bound(dev),
 150              "PM domains can only be changed for unbound devices\n");
 151         dev->pm_domain = pd;
 152         device_pm_check_callbacks(dev);
 153 }
 154 EXPORT_SYMBOL_GPL(dev_pm_domain_set);