Line data    Source code

       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           0 : int dev_pm_get_subsys_data(struct device *dev)
      26             : {
      27             :         struct pm_subsys_data *psd;
      28             : 
      29           0 :         psd = kzalloc(sizeof(*psd), GFP_KERNEL);
      30           0 :         if (!psd)
      31             :                 return -ENOMEM;
      32             : 
      33           0 :         spin_lock_irq(&dev->power.lock);
      34             : 
      35           0 :         if (dev->power.subsys_data) {
      36           0 :                 dev->power.subsys_data->refcount++;
      37             :         } else {
      38           0 :                 spin_lock_init(&psd->lock);
      39           0 :                 psd->refcount = 1;
      40           0 :                 dev->power.subsys_data = psd;
      41           0 :                 pm_clk_init(dev);
      42           0 :                 psd = NULL;
      43             :         }
      44             : 
      45           0 :         spin_unlock_irq(&dev->power.lock);
      46             : 
      47             :         /* kfree() verifies that its argument is nonzero. */
      48           0 :         kfree(psd);
      49             : 
      50           0 :         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           0 : void dev_pm_put_subsys_data(struct device *dev)
      62             : {
      63             :         struct pm_subsys_data *psd;
      64             : 
      65           0 :         spin_lock_irq(&dev->power.lock);
      66             : 
      67           0 :         psd = dev_to_psd(dev);
      68           0 :         if (!psd)
      69             :                 goto out;
      70             : 
      71           0 :         if (--psd->refcount == 0)
      72           0 :                 dev->power.subsys_data = NULL;
      73             :         else
      74             :                 psd = NULL;
      75             : 
      76             :  out:
      77           0 :         spin_unlock_irq(&dev->power.lock);
      78           0 :         kfree(psd);
      79           0 : }
      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           5 : 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           0 : struct device *dev_pm_domain_attach_by_id(struct device *dev,
     144             :                                           unsigned int index)
     145             : {
     146           0 :         if (dev->pm_domain)
     147             :                 return ERR_PTR(-EEXIST);
     148             : 
     149           0 :         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           0 : struct device *dev_pm_domain_attach_by_name(struct device *dev,
     161             :                                             const char *name)
     162             : {
     163           0 :         if (dev->pm_domain)
     164             :                 return ERR_PTR(-EEXIST);
     165             : 
     166           0 :         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(),
     176             :  * dev_pm_domain_attach_by_id() and dev_pm_domain_attach_by_name(), thus it
     177             :  * detaches @dev from its PM domain.  Typically it should be invoked during the
     178             :  * remove phase, either from subsystem level code or from drivers.
     179             :  *
     180             :  * Callers must ensure proper synchronization of this function with power
     181             :  * management callbacks.
     182             :  */
     183           5 : void dev_pm_domain_detach(struct device *dev, bool power_off)
     184             : {
     185           5 :         if (dev->pm_domain && dev->pm_domain->detach)
     186           0 :                 dev->pm_domain->detach(dev, power_off);
     187           5 : }
     188             : EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
     189             : 
     190             : /**
     191             :  * dev_pm_domain_start - Start the device through its PM domain.
     192             :  * @dev: Device to start.
     193             :  *
     194             :  * This function should typically be called during probe by a subsystem/driver,
     195             :  * when it needs to start its device from the PM domain's perspective. Note
     196             :  * that, it's assumed that the PM domain is already powered on when this
     197             :  * function is called.
     198             :  *
     199             :  * Returns 0 on success and negative error values on failures.
     200             :  */
     201           0 : int dev_pm_domain_start(struct device *dev)
     202             : {
     203           0 :         if (dev->pm_domain && dev->pm_domain->start)
     204           0 :                 return dev->pm_domain->start(dev);
     205             : 
     206             :         return 0;
     207             : }
     208             : EXPORT_SYMBOL_GPL(dev_pm_domain_start);
     209             : 
     210             : /**
     211             :  * dev_pm_domain_set - Set PM domain of a device.
     212             :  * @dev: Device whose PM domain is to be set.
     213             :  * @pd: PM domain to be set, or NULL.
     214             :  *
     215             :  * Sets the PM domain the device belongs to. The PM domain of a device needs
     216             :  * to be set before its probe finishes (it's bound to a driver).
     217             :  *
     218             :  * This function must be called with the device lock held.
     219             :  */
     220           0 : void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
     221             : {
     222           0 :         if (dev->pm_domain == pd)
     223             :                 return;
     224             : 
     225           0 :         WARN(pd && device_is_bound(dev),
     226             :              "PM domains can only be changed for unbound devices\n");
     227           0 :         dev->pm_domain = pd;
     228           0 :         device_pm_check_callbacks(dev);
     229             : }
     230             : EXPORT_SYMBOL_GPL(dev_pm_domain_set);