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 #include <linux/acpi.h>
15 #include <linux/pm_domain.h>
16
17 /**
18 * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
19 * @dev: Device to handle.
20 *
21 * If power.subsys_data is NULL, point it to a new object, otherwise increment
22 * its reference counter. Return 1 if a new object has been created, otherwise
23 * return 0 or error code.
24 */
dev_pm_get_subsys_data(struct device * dev)25 int dev_pm_get_subsys_data(struct device *dev)
26 {
27 struct pm_subsys_data *psd;
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 }
44
45 spin_unlock_irq(&dev->power.lock);
46
47 /* kfree() verifies that its argument is nonzero. */
48 kfree(psd);
49
50 return 0;
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 = 1;
66
67 spin_lock_irq(&dev->power.lock);
68
69 psd = dev_to_psd(dev);
70 if (!psd)
71 goto out;
72
73 if (--psd->refcount == 0) {
74 dev->power.subsys_data = NULL;
75 } else {
76 psd = NULL;
77 ret = 0;
78 }
79
80 out:
81 spin_unlock_irq(&dev->power.lock);
82 kfree(psd);
83
84 return ret;
85 }
86 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
87
88 /**
89 * dev_pm_domain_attach - Attach a device to its PM domain.
90 * @dev: Device to attach.
91 * @power_on: Used to indicate whether we should power on the device.
92 *
93 * The @dev may only be attached to a single PM domain. By iterating through
94 * the available alternatives we try to find a valid PM domain for the device.
95 * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
96 * should be assigned by the corresponding attach function.
97 *
98 * This function should typically be invoked from subsystem level code during
99 * the probe phase. Especially for those that holds devices which requires
100 * power management through PM domains.
101 *
102 * Callers must ensure proper synchronization of this function with power
103 * management callbacks.
104 *
105 * Returns 0 on successfully attached PM domain or negative error code.
106 */
dev_pm_domain_attach(struct device * dev,bool power_on)107 int dev_pm_domain_attach(struct device *dev, bool power_on)
108 {
109 int ret;
110
111 ret = acpi_dev_pm_attach(dev, power_on);
112 if (ret)
113 ret = genpd_dev_pm_attach(dev);
114
115 return ret;
116 }
117 EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
118
119 /**
120 * dev_pm_domain_detach - Detach a device from its PM domain.
121 * @dev: Device to attach.
122 * @power_off: Used to indicate whether we should power off the device.
123 *
124 * This functions will reverse the actions from dev_pm_domain_attach() and thus
125 * try to detach the @dev from its PM domain. Typically it should be invoked
126 * from subsystem level code during the remove phase.
127 *
128 * Callers must ensure proper synchronization of this function with power
129 * management callbacks.
130 */
dev_pm_domain_detach(struct device * dev,bool power_off)131 void dev_pm_domain_detach(struct device *dev, bool power_off)
132 {
133 if (dev->pm_domain && dev->pm_domain->detach)
134 dev->pm_domain->detach(dev, power_off);
135 }
136 EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
137