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
  28         psd = kzalloc(sizeof(*psd), GFP_KERNEL);
  29         if (!psd)
  30                 return -ENOMEM;
  31
  32         spin_lock_irq(&dev->power.lock);
  33
  34         if (dev->power.subsys_data) {
  35                 dev->power.subsys_data->refcount++;
  36         } else {
  37                 spin_lock_init(&psd->lock);
  38                 psd->refcount = 1;
  39                 dev->power.subsys_data = psd;
  40                 pm_clk_init(dev);
  41                 psd = NULL;
  42         }
  43
  44         spin_unlock_irq(&dev->power.lock);
  45
  46         /* kfree() verifies that its argument is nonzero. */
  47         kfree(psd);
  48
  49         return 0;
  50 }
  51 EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
  52
  53 /**
  54  * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
  55  * @dev: Device to handle.
  56  *
  57  * If the reference counter of power.subsys_data is zero after dropping the
  58  * reference, power.subsys_data is removed.  Return 1 if that happens or 0
  59  * otherwise.
  60  */
  61 int dev_pm_put_subsys_data(struct device *dev)
  62 {
  63         struct pm_subsys_data *psd;
  64         int ret = 1;
  65
  66         spin_lock_irq(&dev->power.lock);
  67
  68         psd = dev_to_psd(dev);
  69         if (!psd)
  70                 goto out;
  71
  72         if (--psd->refcount == 0) {
  73                 dev->power.subsys_data = NULL;
  74         } else {
  75                 psd = NULL;
  76                 ret = 0;
  77         }
  78
  79  out:
  80         spin_unlock_irq(&dev->power.lock);
  81         kfree(psd);
  82
  83         return ret;
  84 }
  85 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);