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  */
dev_pm_get_subsys_data(struct device * dev)27 int 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 }
54 EXPORT_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  */
dev_pm_put_subsys_data(struct device * dev)63 void 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 }
82 EXPORT_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  */
dev_pm_domain_attach(struct device * dev,bool power_on)104 int 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 }
117 EXPORT_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  */
dev_pm_domain_attach_by_id(struct device * dev,unsigned int index)145 struct 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 }
153 EXPORT_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  */
dev_pm_domain_attach_by_name(struct device * dev,char * name)162 struct device *dev_pm_domain_attach_by_name(struct device *dev,
163 					    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 }
170 EXPORT_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  */
dev_pm_domain_detach(struct device * dev,bool power_off)185 void 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 }
190 EXPORT_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  */
dev_pm_domain_set(struct device * dev,struct dev_pm_domain * pd)202 void 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 }
212 EXPORT_SYMBOL_GPL(dev_pm_domain_set);
213