drivers/base/power/common.c

   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_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 int dev_pm_domain_start(struct device *dev)
 202 {
 203         if (dev->pm_domain && dev->pm_domain->start)
 204                 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 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
 221 {
 222         if (dev->pm_domain == pd)
 223                 return;
 224
 225         WARN(pd && device_is_bound(dev),
 226              "PM domains can only be changed for unbound devices\n");
 227         dev->pm_domain = pd;
 228         device_pm_check_callbacks(dev);
 229 }
 230 EXPORT_SYMBOL_GPL(dev_pm_domain_set);