1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * drivers/base/power/common.c - Common device power management code.
4 *
5 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
6 */
7 #include <linux/kernel.h>
8 #include <linux/device.h>
9 #include <linux/export.h>
10 #include <linux/slab.h>
11 #include <linux/pm_clock.h>
12 #include <linux/acpi.h>
13 #include <linux/pm_domain.h>
14
15 #include "power.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 0 if new object has been created or refcount
23 * increased, otherwise negative error code.
24 */
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.
60 */
61 void dev_pm_put_subsys_data(struct device *dev)
62 {
63 struct pm_subsys_data *psd;
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
76 out:
77 spin_unlock_irq(&dev->power.lock);
78 kfree(psd);
79 }
80 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
81
82 /**
83 * dev_pm_domain_attach - Attach a device to its PM domain.
84 * @dev: Device to attach.
85 * @power_on: Used to indicate whether we should power on the device.
86 *
87 * The @dev may only be attached to a single PM domain. By iterating through
88 * the available alternatives we try to find a valid PM domain for the device.
89 * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
90 * should be assigned by the corresponding attach function.
91 *
92 * This function should typically be invoked from subsystem level code during
93 * the probe phase. Especially for those that holds devices which requires
94 * power management through PM domains.
95 *
96 * Callers must ensure proper synchronization of this function with power
97 * management callbacks.
98 *
99 * Returns 0 on successfully attached PM domain, or when it is found that the
100 * device doesn't need a PM domain, else a negative error code.
101 */
102 int dev_pm_domain_attach(struct device *dev, bool power_on)
103 {
104 int ret;
105
106 if (dev->pm_domain)
107 return 0;
108
109 ret = acpi_dev_pm_attach(dev, power_on);
110 if (!ret)
111 ret = genpd_dev_pm_attach(dev);
112
113 return ret < 0 ? ret : 0;
114 }
115 EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
116
117 /**
118 * dev_pm_domain_attach_by_id - Associate a device with one of its PM domains.
119 * @dev: The device used to lookup the PM domain.
120 * @index: The index of the PM domain.
121 *
122 * As @dev may only be attached to a single PM domain, the backend PM domain
123 * provider creates a virtual device to attach instead. If attachment succeeds,
124 * the ->detach() callback in the struct dev_pm_domain are assigned by the
125 * corresponding backend attach function, as to deal with detaching of the
126 * created virtual device.
127 *
128 * This function should typically be invoked by a driver during the probe phase,
129 * in case its device requires power management through multiple PM domains. The
130 * driver may benefit from using the received device, to configure device-links
131 * towards its original device. Depending on the use-case and if needed, the
132 * links may be dynamically changed by the driver, which allows it to control
133 * the power to the PM domains independently from each other.
134 *
135 * Callers must ensure proper synchronization of this function with power
136 * management callbacks.
137 *
138 * Returns the virtual created device when successfully attached to its PM
139 * domain, NULL in case @dev don't need a PM domain, else an ERR_PTR().
140 * Note that, to detach the returned virtual device, the driver shall call
141 * dev_pm_domain_detach() on it, typically during the remove phase.
142 */
143 struct device *dev_pm_domain_attach_by_id(struct device *dev,
144 unsigned int index)
145 {
146 if (dev->pm_domain)
147 return ERR_PTR(-EEXIST);
148
149 return genpd_dev_pm_attach_by_id(dev, index);
150 }
151 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_id);
152
153 /**
154 * dev_pm_domain_attach_by_name - Associate a device with one of its PM domains.
155 * @dev: The device used to lookup the PM domain.
156 * @name: The name of the PM domain.
157 *
158 * For a detailed function description, see dev_pm_domain_attach_by_id().
159 */
160 struct device *dev_pm_domain_attach_by_name(struct device *dev,
161 const char *name)
162 {
163 if (dev->pm_domain)
164 return ERR_PTR(-EEXIST);
165
166 return genpd_dev_pm_attach_by_name(dev, name);
167 }
168 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_name);
169
170 /**
171 * dev_pm_domain_detach - Detach a device from its PM domain.
172 * @dev: Device to detach.
173 * @power_off: Used to indicate whether we should power off the device.
174 *
175 * This functions will reverse the actions from dev_pm_domain_attach() and
176 * dev_pm_domain_attach_by_id(), thus it detaches @dev from its PM domain.
177 * Typically it should be invoked during the remove phase, either from
178 * subsystem level code or from drivers.
179 *
180 * Callers must ensure proper synchronization of this function with power
181 * management callbacks.
182 */
183 void dev_pm_domain_detach(struct device *dev, bool power_off)
184 {
185 if (dev->pm_domain && dev->pm_domain->detach)
186 dev->pm_domain->detach(dev, power_off);
187 }
188 EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
189
190 /**
191 * dev_pm_domain_set - Set PM domain of a device.
192 * @dev: Device whose PM domain is to be set.
193 * @pd: PM domain to be set, or NULL.
194 *
195 * Sets the PM domain the device belongs to. The PM domain of a device needs
196 * to be set before its probe finishes (it's bound to a driver).
197 *
198 * This function must be called with the device lock held.
199 */
200 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
201 {
202 if (dev->pm_domain == pd)
203 return;
204
205 WARN(pd && device_is_bound(dev),
206 "PM domains can only be changed for unbound devices\n");
207 dev->pm_domain = pd;
208 device_pm_check_callbacks(dev);
209 }
210 EXPORT_SYMBOL_GPL(dev_pm_domain_set);