/*
* suspend.c - Functions for putting devices to sleep.
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Open Source Development Labs
*
* This file is released under the GPLv2
*
*/
#include <linux/device.h>
#include "../base.h"
#include "power.h"
/*
* The entries in the dpm_active list are in a depth first order, simply
* because children are guaranteed to be discovered after parents, and
* are inserted at the back of the list on discovery.
*
* All list on the suspend path are done in reverse order, so we operate
* on the leaves of the device tree (or forests, depending on how you want
* to look at it ;) first. As nodes are removed from the back of the list,
* they are inserted into the front of their destintation lists.
*
* Things are the reverse on the resume path - iterations are done in
* forward order, and nodes are inserted at the back of their destination
* lists. This way, the ancestors will be accessed before their descendents.
*/
/**
* suspend_device - Save state of one device.
* @dev: Device.
* @state: Power state device is entering.
*/
int suspend_device(struct device * dev, pm_message_t state)
{
int error = 0;
down(&dev->sem);
if (dev->power.power_state.event) {
dev_dbg(dev, "PM: suspend %d-->%d\n",
dev->power.power_state.event, state.event);
}
if (dev->power.pm_parent
&& dev->power.pm_parent->power.power_state.event) {
dev_err(dev,
"PM: suspend %d->%d, parent %s already %d\n",
dev->power.power_state.event, state.event,
dev->power.pm_parent->bus_id,
dev->power.pm_parent->power.power_state.event);
}
dev->power.prev_state = dev->power.power_state;
if (dev->bus && dev->bus->suspend && !dev->power.power_state.event) {
dev_dbg(dev, "suspending\n");
error = dev->bus->suspend(dev, state);
}
up(&dev->sem);
return error;
}
/**
* device_suspend - Save state and stop all devices in system.
* @state: Power state to put each device in.
*
* Walk the dpm_active list, call ->suspend() for each device, and move
* it to dpm_off.
* Check the return value for each. If it returns 0, then we move the
* the device to the dpm_off list. If it returns -EAGAIN, we move it to
* the dpm_off_irq list. If we get a different error, try and back out.
*
* If we hit a failure with any of the devices, call device_resume()
* above to bring the suspended devices back to life.
*
*/
int device_suspend(pm_message_t state)
{
int error = 0;
down(&dpm_sem);
down(&dpm_list_sem);
while (!list_empty(&dpm_active) && error == 0) {
struct list_head * entry = dpm_active.prev;
struct device * dev = to_device(entry);
get_device(dev);
up(&dpm_list_sem);
error = suspend_device(dev, state);
down(&dpm_list_sem);
/* Check if the device got removed */
if (!list_empty(&dev->power.entry)) {
/* Move it to the dpm_off or dpm_off_irq list */
if (!error) {
list_del(&dev->power.entry);
list_add(&dev->power.entry, &dpm_off);
} else if (error == -EAGAIN) {
list_del(&dev->power.entry);
list_add(&dev->power.entry, &dpm_off_irq);
error = 0;
}
}
if (error)
printk(KERN_ERR "Could not suspend device %s: "
"error %d\n", kobject_name(&dev->kobj), error);
put_device(dev);
}
up(&dpm_list_sem);
if (error) {
/* we failed... before resuming, bring back devices from
* dpm_off_irq list back to main dpm_off list, we do want
* to call resume() on them, in case they partially suspended
* despite returning -EAGAIN
*/
while (!list_empty(&dpm_off_irq)) {
struct list_head * entry = dpm_off_irq.next;
list_del(entry);
list_add(entry, &dpm_off);
}
dpm_resume();
}
up(&dpm_sem);
return error;
}
EXPORT_SYMBOL_GPL(device_suspend);
/**
* device_power_down - Shut down special devices.
* @state: Power state to enter.
*
* Walk the dpm_off_irq list, calling ->power_down() for each device that
* couldn't power down the device with interrupts enabled. When we're
* done, power down system devices.
*/
int device_power_down(pm_message_t state)
{
int error = 0;
struct device * dev;
list_for_each_entry_reverse(dev, &dpm_off_irq, power.entry) {
if ((error = suspend_device(dev, state)))
break;
}
if (error)
goto Error;
if ((error = sysdev_suspend(state)))
goto Error;
Done:
return error;
Error:
printk(KERN_ERR "Could not power down device %s: "
"error %d\n", kobject_name(&dev->kobj), error);
dpm_power_up();
goto Done;
}
EXPORT_SYMBOL_GPL(device_power_down);
