1 /* 2 * drivers/base/power/main.c - Where the driver meets power management. 3 * 4 * Copyright (c) 2003 Patrick Mochel 5 * Copyright (c) 2003 Open Source Development Lab 6 * 7 * This file is released under the GPLv2 8 * 9 * 10 * The driver model core calls device_pm_add() when a device is registered. 11 * This will intialize the embedded device_pm_info object in the device 12 * and add it to the list of power-controlled devices. sysfs entries for 13 * controlling device power management will also be added. 14 * 15 * A different set of lists than the global subsystem list are used to 16 * keep track of power info because we use different lists to hold 17 * devices based on what stage of the power management process they 18 * are in. The power domain dependencies may also differ from the 19 * ancestral dependencies that the subsystem list maintains. 20 */ 21 22 #include <linux/config.h> 23 #include <linux/device.h> 24 #include "power.h" 25 26 LIST_HEAD(dpm_active); 27 LIST_HEAD(dpm_off); 28 LIST_HEAD(dpm_off_irq); 29 30 DECLARE_MUTEX(dpm_sem); 31 DECLARE_MUTEX(dpm_list_sem); 32 33 /* 34 * PM Reference Counting. 35 */ 36 37 static inline void device_pm_hold(struct device * dev) 38 { 39 if (dev) 40 atomic_inc(&dev->power.pm_users); 41 } 42 43 static inline void device_pm_release(struct device * dev) 44 { 45 if (dev) 46 atomic_dec(&dev->power.pm_users); 47 } 48 49 50 /** 51 * device_pm_set_parent - Specify power dependency. 52 * @dev: Device who needs power. 53 * @parent: Device that supplies power. 54 * 55 * This function is used to manually describe a power-dependency 56 * relationship. It may be used to specify a transversal relationship 57 * (where the power supplier is not the physical (or electrical) 58 * ancestor of a specific device. 59 * The effect of this is that the supplier will not be powered down 60 * before the power dependent. 61 */ 62 63 void device_pm_set_parent(struct device * dev, struct device * parent) 64 { 65 struct device * old_parent = dev->power.pm_parent; 66 device_pm_release(old_parent); 67 dev->power.pm_parent = parent; 68 device_pm_hold(parent); 69 } 70 EXPORT_SYMBOL_GPL(device_pm_set_parent); 71 72 int device_pm_add(struct device * dev) 73 { 74 int error; 75 76 pr_debug("PM: Adding info for %s:%s\n", 77 dev->bus ? dev->bus->name : "No Bus", dev->kobj.name); 78 atomic_set(&dev->power.pm_users, 0); 79 down(&dpm_list_sem); 80 list_add_tail(&dev->power.entry, &dpm_active); 81 device_pm_set_parent(dev, dev->parent); 82 if ((error = dpm_sysfs_add(dev))) 83 list_del(&dev->power.entry); 84 up(&dpm_list_sem); 85 return error; 86 } 87 88 void device_pm_remove(struct device * dev) 89 { 90 pr_debug("PM: Removing info for %s:%s\n", 91 dev->bus ? dev->bus->name : "No Bus", dev->kobj.name); 92 down(&dpm_list_sem); 93 dpm_sysfs_remove(dev); 94 device_pm_release(dev->power.pm_parent); 95 list_del_init(&dev->power.entry); 96 up(&dpm_list_sem); 97 } 98 99 100