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/*
* drivers/base/power/sysfs.c - sysfs entries for device PM
*/
#include <linux/device.h>
#include "power.h"
/**
* state - Control current power state of device
*
* show() returns the current power state of the device. '0' indicates
* the device is on. Other values (1-3) indicate the device is in a low
* power state.
*
* store() sets the current power state, which is an integer value
* between 0-3. If the device is on ('0'), and the value written is
* greater than 0, then the device is placed directly into the low-power
* state (via its driver's ->suspend() method).
* If the device is currently in a low-power state, and the value is 0,
* the device is powered back on (via the ->resume() method).
* If the device is in a low-power state, and a different low-power state
* is requested, the device is first resumed, then suspended into the new
* low-power state.
*/
static ssize_t state_show(struct device * dev, struct device_attribute *attr, char * buf)
{
return sprintf(buf, "%u\n", dev->power.power_state);
}
static ssize_t state_store(struct device * dev, struct device_attribute *attr, const char * buf, size_t n)
{
u32 state;
char * rest;
int error = 0;
state = simple_strtoul(buf, &rest, 10);
if (*rest)
return -EINVAL;
if (state)
error = dpm_runtime_suspend(dev, state);
else
dpm_runtime_resume(dev);
return error ? error : n;
}
static DEVICE_ATTR(state, 0644, state_show, state_store);
static struct attribute * power_attrs[] = {
&dev_attr_state.attr,
NULL,
};
static struct attribute_group pm_attr_group = {
.name = "power",
.attrs = power_attrs,
};
int dpm_sysfs_add(struct device * dev)
{
return sysfs_create_group(&dev->kobj, &pm_attr_group);
}
void dpm_sysfs_remove(struct device * dev)
{
sysfs_remove_group(&dev->kobj, &pm_attr_group);
}
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