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