/* * drivers/base/power/main.c - Where the driver meets power management. * * Copyright (c) 2003 Patrick Mochel * Copyright (c) 2003 Open Source Development Lab * * This file is released under the GPLv2 * * * The driver model core calls device_pm_add() when a device is registered. * This will intialize the embedded device_pm_info object in the device * and add it to the list of power-controlled devices. sysfs entries for * controlling device power management will also be added. * * A different set of lists than the global subsystem list are used to * keep track of power info because we use different lists to hold * devices based on what stage of the power management process they * are in. The power domain dependencies may also differ from the * ancestral dependencies that the subsystem list maintains. */ #include <linux/config.h> #include <linux/device.h> #include "power.h" LIST_HEAD(dpm_active); LIST_HEAD(dpm_off); LIST_HEAD(dpm_off_irq); DECLARE_MUTEX(dpm_sem); DECLARE_MUTEX(dpm_list_sem); /* * PM Reference Counting. */ static inline void device_pm_hold(struct device * dev) { if (dev) atomic_inc(&dev->power.pm_users); } static inline void device_pm_release(struct device * dev) { if (dev) atomic_dec(&dev->power.pm_users); } /** * device_pm_set_parent - Specify power dependency. * @dev: Device who needs power. * @parent: Device that supplies power. * * This function is used to manually describe a power-dependency * relationship. It may be used to specify a transversal relationship * (where the power supplier is not the physical (or electrical) * ancestor of a specific device. * The effect of this is that the supplier will not be powered down * before the power dependent. */ void device_pm_set_parent(struct device * dev, struct device * parent) { struct device * old_parent = dev->power.pm_parent; device_pm_release(old_parent); dev->power.pm_parent = parent; device_pm_hold(parent); } EXPORT_SYMBOL_GPL(device_pm_set_parent); int device_pm_add(struct device * dev) { int error; pr_debug("PM: Adding info for %s:%s\n", dev->bus ? dev->bus->name : "No Bus", dev->kobj.name); atomic_set(&dev->power.pm_users, 0); down(&dpm_list_sem); list_add_tail(&dev->power.entry, &dpm_active); device_pm_set_parent(dev, dev->parent); if ((error = dpm_sysfs_add(dev))) list_del(&dev->power.entry); up(&dpm_list_sem); return error; } void device_pm_remove(struct device * dev) { pr_debug("PM: Removing info for %s:%s\n", dev->bus ? dev->bus->name : "No Bus", dev->kobj.name); down(&dpm_list_sem); dpm_sysfs_remove(dev); device_pm_release(dev->power.pm_parent); list_del_init(&dev->power.entry); up(&dpm_list_sem); }