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/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  */
dev_pm_get_subsys_data(struct device * dev)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 		spin_lock_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  */
dev_pm_put_subsys_data(struct device * dev)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);
87