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/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/pm_clock.h>
  14
  15 /**
  16  * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
  17  * @dev: Device to handle.
  18  *
  19  * If power.subsys_data is NULL, point it to a new object, otherwise increment
  20  * its reference counter.  Return 1 if a new object has been created, otherwise
  21  * return 0 or error code.
  22  */
  23 int dev_pm_get_subsys_data(struct device *dev)
  24 {
  25         struct pm_subsys_data *psd;
  26         int ret = 0;
  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                 mutex_init(&psd->lock);
  38                 psd->refcount = 1;
  39                 dev->power.subsys_data = psd;
  40                 pm_clk_init(dev);
  41                 psd = NULL;
  42                 ret = 1;
  43         }
  44
  45         spin_unlock_irq(&dev->power.lock);
  46
  47         /* kfree() verifies that its argument is nonzero. */
  48         kfree(psd);
  49
  50         return ret;
  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 = 0;
  66
  67         spin_lock_irq(&dev->power.lock);
  68
  69         psd = dev_to_psd(dev);
  70         if (!psd) {
  71                 ret = -EINVAL;
  72                 goto out;
  73         }
  74
  75         if (--psd->refcount == 0) {
  76                 dev->power.subsys_data = NULL;
  77                 kfree(psd);
  78                 ret = 1;
  79         }
  80
  81  out:
  82         spin_unlock_irq(&dev->power.lock);
  83
  84         return ret;
  85 }
  86 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);