1 /* 2 * drivers/base/power/runtime.c - Handling dynamic device power management. 3 * 4 * Copyright (c) 2003 Patrick Mochel 5 * Copyright (c) 2003 Open Source Development Lab 6 * 7 */ 8 9 #include <linux/device.h> 10 #include "power.h" 11 12 13 static void runtime_resume(struct device * dev) 14 { 15 dev_dbg(dev, "resuming\n"); 16 if (!dev->power.power_state) 17 return; 18 if (!resume_device(dev)) 19 dev->power.power_state = 0; 20 } 21 22 23 /** 24 * dpm_runtime_resume - Power one device back on. 25 * @dev: Device. 26 * 27 * Bring one device back to the on state by first powering it 28 * on, then restoring state. We only operate on devices that aren't 29 * already on. 30 * FIXME: We need to handle devices that are in an unknown state. 31 */ 32 33 void dpm_runtime_resume(struct device * dev) 34 { 35 down(&dpm_sem); 36 runtime_resume(dev); 37 up(&dpm_sem); 38 } 39 40 41 /** 42 * dpm_runtime_suspend - Put one device in low-power state. 43 * @dev: Device. 44 * @state: State to enter. 45 */ 46 47 int dpm_runtime_suspend(struct device * dev, pm_message_t state) 48 { 49 int error = 0; 50 51 down(&dpm_sem); 52 if (dev->power.power_state == state) 53 goto Done; 54 55 if (dev->power.power_state) 56 runtime_resume(dev); 57 58 if (!(error = suspend_device(dev, state))) 59 dev->power.power_state = state; 60 Done: 61 up(&dpm_sem); 62 return error; 63 } 64 65 66 /** 67 * dpm_set_power_state - Update power_state field. 68 * @dev: Device. 69 * @state: Power state device is in. 70 * 71 * This is an update mechanism for drivers to notify the core 72 * what power state a device is in. Device probing code may not 73 * always be able to tell, but we need accurate information to 74 * work reliably. 75 */ 76 void dpm_set_power_state(struct device * dev, pm_message_t state) 77 { 78 down(&dpm_sem); 79 dev->power.power_state = state; 80 up(&dpm_sem); 81 } 82