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 /**
  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 1 if a new object has been created, otherwise
  23  * return 0 or error code.
  24  */
  25 int 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 }
  52 EXPORT_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.  Return 1 if that happens or 0
  60  * otherwise.
  61  */
  62 int dev_pm_put_subsys_data(struct device *dev)
  63 {
  64         struct pm_subsys_data *psd;
  65         int ret = 1;
  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                 ret = 0;
  78         }
  79
  80  out:
  81         spin_unlock_irq(&dev->power.lock);
  82         kfree(psd);
  83
  84         return ret;
  85 }
  86 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
  87
  88 /**
  89  * dev_pm_domain_attach - Attach a device to its PM domain.
  90  * @dev: Device to attach.
  91  * @power_on: Used to indicate whether we should power on the device.
  92  *
  93  * The @dev may only be attached to a single PM domain. By iterating through
  94  * the available alternatives we try to find a valid PM domain for the device.
  95  * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
  96  * should be assigned by the corresponding attach function.
  97  *
  98  * This function should typically be invoked from subsystem level code during
  99  * the probe phase. Especially for those that holds devices which requires
 100  * power management through PM domains.
 101  *
 102  * Callers must ensure proper synchronization of this function with power
 103  * management callbacks.
 104  *
 105  * Returns 0 on successfully attached PM domain or negative error code.
 106  */
 107 int dev_pm_domain_attach(struct device *dev, bool power_on)
 108 {
 109         int ret;
 110
 111         ret = acpi_dev_pm_attach(dev, power_on);
 112         if (ret)
 113                 ret = genpd_dev_pm_attach(dev);
 114
 115         return ret;
 116 }
 117 EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
 118
 119 /**
 120  * dev_pm_domain_detach - Detach a device from its PM domain.
 121  * @dev: Device to attach.
 122  * @power_off: Used to indicate whether we should power off the device.
 123  *
 124  * This functions will reverse the actions from dev_pm_domain_attach() and thus
 125  * try to detach the @dev from its PM domain. Typically it should be invoked
 126  * from subsystem level code during the remove phase.
 127  *
 128  * Callers must ensure proper synchronization of this function with power
 129  * management callbacks.
 130  */
 131 void dev_pm_domain_detach(struct device *dev, bool power_off)
 132 {
 133         if (dev->pm_domain && dev->pm_domain->detach)
 134                 dev->pm_domain->detach(dev, power_off);
 135 }
 136 EXPORT_SYMBOL_GPL(dev_pm_domain_detach);