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 0 if new object has been created or refcount
  23  * increased, otherwise negative 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.
  60  */
  61 void 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 }
  80 EXPORT_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 negative error code.
 100  */
 101 int dev_pm_domain_attach(struct device *dev, bool power_on)
 102 {
 103         int ret;
 104
 105         ret = acpi_dev_pm_attach(dev, power_on);
 106         if (ret)
 107                 ret = genpd_dev_pm_attach(dev);
 108
 109         return ret;
 110 }
 111 EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
 112
 113 /**
 114  * dev_pm_domain_detach - Detach a device from its PM domain.
 115  * @dev: Device to attach.
 116  * @power_off: Used to indicate whether we should power off the device.
 117  *
 118  * This functions will reverse the actions from dev_pm_domain_attach() and thus
 119  * try to detach the @dev from its PM domain. Typically it should be invoked
 120  * from subsystem level code during the remove phase.
 121  *
 122  * Callers must ensure proper synchronization of this function with power
 123  * management callbacks.
 124  */
 125 void dev_pm_domain_detach(struct device *dev, bool power_off)
 126 {
 127         if (dev->pm_domain && dev->pm_domain->detach)
 128                 dev->pm_domain->detach(dev, power_off);
 129 }
 130 EXPORT_SYMBOL_GPL(dev_pm_domain_detach);