base/power/common.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * drivers/base/power/common.c - Common device power management code.
0004  *
0005  * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
0006  */
0007 #include <linux/kernel.h>
0008 #include <linux/device.h>
0009 #include <linux/export.h>
0010 #include <linux/slab.h>
0011 #include <linux/pm_clock.h>
0012 #include <linux/acpi.h>
0013 #include <linux/pm_domain.h>
0014
0015 #include "power.h"
0016
0017 /**
0018  * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
0019  * @dev: Device to handle.
0020  *
0021  * If power.subsys_data is NULL, point it to a new object, otherwise increment
0022  * its reference counter.  Return 0 if new object has been created or refcount
0023  * increased, otherwise negative error code.
0024  */
0025 int dev_pm_get_subsys_data(struct device *dev)
0026 {
0027     struct pm_subsys_data *psd;
0028
0029     psd = kzalloc(sizeof(*psd), GFP_KERNEL);
0030     if (!psd)
0031         return -ENOMEM;
0032
0033     spin_lock_irq(&dev->power.lock);
0034
0035     if (dev->power.subsys_data) {
0036         dev->power.subsys_data->refcount++;
0037     } else {
0038         spin_lock_init(&psd->lock);
0039         psd->refcount = 1;
0040         dev->power.subsys_data = psd;
0041         pm_clk_init(dev);
0042         psd = NULL;
0043     }
0044
0045     spin_unlock_irq(&dev->power.lock);
0046
0047     /* kfree() verifies that its argument is nonzero. */
0048     kfree(psd);
0049
0050     return 0;
0051 }
0052 EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
0053
0054 /**
0055  * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
0056  * @dev: Device to handle.
0057  *
0058  * If the reference counter of power.subsys_data is zero after dropping the
0059  * reference, power.subsys_data is removed.
0060  */
0061 void dev_pm_put_subsys_data(struct device *dev)
0062 {
0063     struct pm_subsys_data *psd;
0064
0065     spin_lock_irq(&dev->power.lock);
0066
0067     psd = dev_to_psd(dev);
0068     if (!psd)
0069         goto out;
0070
0071     if (--psd->refcount == 0)
0072         dev->power.subsys_data = NULL;
0073     else
0074         psd = NULL;
0075
0076  out:
0077     spin_unlock_irq(&dev->power.lock);
0078     kfree(psd);
0079 }
0080 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
0081
0082 /**
0083  * dev_pm_domain_attach - Attach a device to its PM domain.
0084  * @dev: Device to attach.
0085  * @power_on: Used to indicate whether we should power on the device.
0086  *
0087  * The @dev may only be attached to a single PM domain. By iterating through
0088  * the available alternatives we try to find a valid PM domain for the device.
0089  * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
0090  * should be assigned by the corresponding attach function.
0091  *
0092  * This function should typically be invoked from subsystem level code during
0093  * the probe phase. Especially for those that holds devices which requires
0094  * power management through PM domains.
0095  *
0096  * Callers must ensure proper synchronization of this function with power
0097  * management callbacks.
0098  *
0099  * Returns 0 on successfully attached PM domain, or when it is found that the
0100  * device doesn't need a PM domain, else a negative error code.
0101  */
0102 int dev_pm_domain_attach(struct device *dev, bool power_on)
0103 {
0104     int ret;
0105
0106     if (dev->pm_domain)
0107         return 0;
0108
0109     ret = acpi_dev_pm_attach(dev, power_on);
0110     if (!ret)
0111         ret = genpd_dev_pm_attach(dev);
0112
0113     return ret < 0 ? ret : 0;
0114 }
0115 EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
0116
0117 /**
0118  * dev_pm_domain_attach_by_id - Associate a device with one of its PM domains.
0119  * @dev: The device used to lookup the PM domain.
0120  * @index: The index of the PM domain.
0121  *
0122  * As @dev may only be attached to a single PM domain, the backend PM domain
0123  * provider creates a virtual device to attach instead. If attachment succeeds,
0124  * the ->detach() callback in the struct dev_pm_domain are assigned by the
0125  * corresponding backend attach function, as to deal with detaching of the
0126  * created virtual device.
0127  *
0128  * This function should typically be invoked by a driver during the probe phase,
0129  * in case its device requires power management through multiple PM domains. The
0130  * driver may benefit from using the received device, to configure device-links
0131  * towards its original device. Depending on the use-case and if needed, the
0132  * links may be dynamically changed by the driver, which allows it to control
0133  * the power to the PM domains independently from each other.
0134  *
0135  * Callers must ensure proper synchronization of this function with power
0136  * management callbacks.
0137  *
0138  * Returns the virtual created device when successfully attached to its PM
0139  * domain, NULL in case @dev don't need a PM domain, else an ERR_PTR().
0140  * Note that, to detach the returned virtual device, the driver shall call
0141  * dev_pm_domain_detach() on it, typically during the remove phase.
0142  */
0143 struct device *dev_pm_domain_attach_by_id(struct device *dev,
0144                       unsigned int index)
0145 {
0146     if (dev->pm_domain)
0147         return ERR_PTR(-EEXIST);
0148
0149     return genpd_dev_pm_attach_by_id(dev, index);
0150 }
0151 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_id);
0152
0153 /**
0154  * dev_pm_domain_attach_by_name - Associate a device with one of its PM domains.
0155  * @dev: The device used to lookup the PM domain.
0156  * @name: The name of the PM domain.
0157  *
0158  * For a detailed function description, see dev_pm_domain_attach_by_id().
0159  */
0160 struct device *dev_pm_domain_attach_by_name(struct device *dev,
0161                         const char *name)
0162 {
0163     if (dev->pm_domain)
0164         return ERR_PTR(-EEXIST);
0165
0166     return genpd_dev_pm_attach_by_name(dev, name);
0167 }
0168 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_name);
0169
0170 /**
0171  * dev_pm_domain_detach - Detach a device from its PM domain.
0172  * @dev: Device to detach.
0173  * @power_off: Used to indicate whether we should power off the device.
0174  *
0175  * This functions will reverse the actions from dev_pm_domain_attach(),
0176  * dev_pm_domain_attach_by_id() and dev_pm_domain_attach_by_name(), thus it
0177  * detaches @dev from its PM domain.  Typically it should be invoked during the
0178  * remove phase, either from subsystem level code or from drivers.
0179  *
0180  * Callers must ensure proper synchronization of this function with power
0181  * management callbacks.
0182  */
0183 void dev_pm_domain_detach(struct device *dev, bool power_off)
0184 {
0185     if (dev->pm_domain && dev->pm_domain->detach)
0186         dev->pm_domain->detach(dev, power_off);
0187 }
0188 EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
0189
0190 /**
0191  * dev_pm_domain_start - Start the device through its PM domain.
0192  * @dev: Device to start.
0193  *
0194  * This function should typically be called during probe by a subsystem/driver,
0195  * when it needs to start its device from the PM domain's perspective. Note
0196  * that, it's assumed that the PM domain is already powered on when this
0197  * function is called.
0198  *
0199  * Returns 0 on success and negative error values on failures.
0200  */
0201 int dev_pm_domain_start(struct device *dev)
0202 {
0203     if (dev->pm_domain && dev->pm_domain->start)
0204         return dev->pm_domain->start(dev);
0205
0206     return 0;
0207 }
0208 EXPORT_SYMBOL_GPL(dev_pm_domain_start);
0209
0210 /**
0211  * dev_pm_domain_set - Set PM domain of a device.
0212  * @dev: Device whose PM domain is to be set.
0213  * @pd: PM domain to be set, or NULL.
0214  *
0215  * Sets the PM domain the device belongs to. The PM domain of a device needs
0216  * to be set before its probe finishes (it's bound to a driver).
0217  *
0218  * This function must be called with the device lock held.
0219  */
0220 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
0221 {
0222     if (dev->pm_domain == pd)
0223         return;
0224
0225     WARN(pd && device_is_bound(dev),
0226          "PM domains can only be changed for unbound devices\n");
0227     dev->pm_domain = pd;
0228     device_pm_check_callbacks(dev);
0229 }
0230 EXPORT_SYMBOL_GPL(dev_pm_domain_set);