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#include "power.h"
18
19/**
20 * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
21 * @dev: Device to handle.
22 *
23 * If power.subsys_data is NULL, point it to a new object, otherwise increment
24 * its reference counter. Return 0 if new object has been created or refcount
25 * increased, otherwise negative error code.
26 */
27int dev_pm_get_subsys_data(struct device *dev)
28{
29 struct pm_subsys_data *psd;
30
31 psd = kzalloc(sizeof(*psd), GFP_KERNEL);
32 if (!psd)
33 return -ENOMEM;
34
35 spin_lock_irq(&dev->power.lock);
36
37 if (dev->power.subsys_data) {
38 dev->power.subsys_data->refcount++;
39 } else {
40 spin_lock_init(&psd->lock);
41 psd->refcount = 1;
42 dev->power.subsys_data = psd;
43 pm_clk_init(dev);
44 psd = NULL;
45 }
46
47 spin_unlock_irq(&dev->power.lock);
48
49 /* kfree() verifies that its argument is nonzero. */
50 kfree(psd);
51
52 return 0;
53}
54EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
55
56/**
57 * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
58 * @dev: Device to handle.
59 *
60 * If the reference counter of power.subsys_data is zero after dropping the
61 * reference, power.subsys_data is removed.
62 */
63void dev_pm_put_subsys_data(struct device *dev)
64{
65 struct pm_subsys_data *psd;
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
78 out:
79 spin_unlock_irq(&dev->power.lock);
80 kfree(psd);
81}
82EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
83
84/**
85 * dev_pm_domain_attach - Attach a device to its PM domain.
86 * @dev: Device to attach.
87 * @power_on: Used to indicate whether we should power on the device.
88 *
89 * The @dev may only be attached to a single PM domain. By iterating through
90 * the available alternatives we try to find a valid PM domain for the device.
91 * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
92 * should be assigned by the corresponding attach function.
93 *
94 * This function should typically be invoked from subsystem level code during
95 * the probe phase. Especially for those that holds devices which requires
96 * power management through PM domains.
97 *
98 * Callers must ensure proper synchronization of this function with power
99 * management callbacks.
100 *
101 * Returns 0 on successfully attached PM domain, or when it is found that the
102 * device doesn't need a PM domain, else a negative error code.
103 */
104int dev_pm_domain_attach(struct device *dev, bool power_on)
105{
106 int ret;
107
108 if (dev->pm_domain)
109 return 0;
110
111 ret = acpi_dev_pm_attach(dev, power_on);
112 if (!ret)
113 ret = genpd_dev_pm_attach(dev);
114
115 return ret < 0 ? ret : 0;
116}
117EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
118
119/**
120 * dev_pm_domain_attach_by_id - Associate a device with one of its PM domains.
121 * @dev: The device used to lookup the PM domain.
122 * @index: The index of the PM domain.
123 *
124 * As @dev may only be attached to a single PM domain, the backend PM domain
125 * provider creates a virtual device to attach instead. If attachment succeeds,
126 * the ->detach() callback in the struct dev_pm_domain are assigned by the
127 * corresponding backend attach function, as to deal with detaching of the
128 * created virtual device.
129 *
130 * This function should typically be invoked by a driver during the probe phase,
131 * in case its device requires power management through multiple PM domains. The
132 * driver may benefit from using the received device, to configure device-links
133 * towards its original device. Depending on the use-case and if needed, the
134 * links may be dynamically changed by the driver, which allows it to control
135 * the power to the PM domains independently from each other.
136 *
137 * Callers must ensure proper synchronization of this function with power
138 * management callbacks.
139 *
140 * Returns the virtual created device when successfully attached to its PM
141 * domain, NULL in case @dev don't need a PM domain, else an ERR_PTR().
142 * Note that, to detach the returned virtual device, the driver shall call
143 * dev_pm_domain_detach() on it, typically during the remove phase.
144 */
145struct device *dev_pm_domain_attach_by_id(struct device *dev,
146 unsigned int index)
147{
148 if (dev->pm_domain)
149 return ERR_PTR(-EEXIST);
150
151 return genpd_dev_pm_attach_by_id(dev, index);
152}
153EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_id);
154
155/**
156 * dev_pm_domain_attach_by_name - Associate a device with one of its PM domains.
157 * @dev: The device used to lookup the PM domain.
158 * @name: The name of the PM domain.
159 *
160 * For a detailed function description, see dev_pm_domain_attach_by_id().
161 */
162struct device *dev_pm_domain_attach_by_name(struct device *dev,
163 const char *name)
164{
165 if (dev->pm_domain)
166 return ERR_PTR(-EEXIST);
167
168 return genpd_dev_pm_attach_by_name(dev, name);
169}
170EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_name);
171
172/**
173 * dev_pm_domain_detach - Detach a device from its PM domain.
174 * @dev: Device to detach.
175 * @power_off: Used to indicate whether we should power off the device.
176 *
177 * This functions will reverse the actions from dev_pm_domain_attach() and
178 * dev_pm_domain_attach_by_id(), thus it detaches @dev from its PM domain.
179 * Typically it should be invoked during the remove phase, either from
180 * subsystem level code or from drivers.
181 *
182 * Callers must ensure proper synchronization of this function with power
183 * management callbacks.
184 */
185void dev_pm_domain_detach(struct device *dev, bool power_off)
186{
187 if (dev->pm_domain && dev->pm_domain->detach)
188 dev->pm_domain->detach(dev, power_off);
189}
190EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
191
192/**
193 * dev_pm_domain_set - Set PM domain of a device.
194 * @dev: Device whose PM domain is to be set.
195 * @pd: PM domain to be set, or NULL.
196 *
197 * Sets the PM domain the device belongs to. The PM domain of a device needs
198 * to be set before its probe finishes (it's bound to a driver).
199 *
200 * This function must be called with the device lock held.
201 */
202void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
203{
204 if (dev->pm_domain == pd)
205 return;
206
207 WARN(pd && device_is_bound(dev),
208 "PM domains can only be changed for unbound devices\n");
209 dev->pm_domain = pd;
210 device_pm_check_callbacks(dev);
211}
212EXPORT_SYMBOL_GPL(dev_pm_domain_set);
213