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/init.h>
  10 #include <linux/kernel.h>
  11 #include <linux/device.h>
  12 #include <linux/export.h>
  13 #include <linux/slab.h>
  14 #include <linux/pm_clock.h>
  15
  16 /**
  17  * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
  18  * @dev: Device to handle.
  19  *
  20  * If power.subsys_data is NULL, point it to a new object, otherwise increment
  21  * its reference counter.  Return 1 if a new object has been created, otherwise
  22  * return 0 or error code.
  23  */
  24 int dev_pm_get_subsys_data(struct device *dev)
  25 {
  26         struct pm_subsys_data *psd;
  27         int ret = 0;
  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                 ret = 1;
  44         }
  45
  46         spin_unlock_irq(&dev->power.lock);
  47
  48         /* kfree() verifies that its argument is nonzero. */
  49         kfree(psd);
  50
  51         return ret;
  52 }
  53 EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
  54
  55 /**
  56  * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
  57  * @dev: Device to handle.
  58  *
  59  * If the reference counter of power.subsys_data is zero after dropping the
  60  * reference, power.subsys_data is removed.  Return 1 if that happens or 0
  61  * otherwise.
  62  */
  63 int dev_pm_put_subsys_data(struct device *dev)
  64 {
  65         struct pm_subsys_data *psd;
  66         int ret = 0;
  67
  68         spin_lock_irq(&dev->power.lock);
  69
  70         psd = dev_to_psd(dev);
  71         if (!psd) {
  72                 ret = -EINVAL;
  73                 goto out;
  74         }
  75
  76         if (--psd->refcount == 0) {
  77                 dev->power.subsys_data = NULL;
  78                 kfree(psd);
  79                 ret = 1;
  80         }
  81
  82  out:
  83         spin_unlock_irq(&dev->power.lock);
  84
  85         return ret;
  86 }
  87 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);