/*
* drivers/base/power/sysfs.c - sysfs entries for device PM
*/
#include <linux/device.h>
#include <linux/string.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.event);
}
static ssize_t state_store(struct device * dev, struct device_attribute *attr, const char * buf, size_t n)
{
pm_message_t state;
char * rest;
int error = 0;
state.event = simple_strtoul(buf, &rest, 10);
if (*rest)
return -EINVAL;
if (state.event)
error = dpm_runtime_suspend(dev, state);
else
dpm_runtime_resume(dev);
return error ? error : n;
}
static DEVICE_ATTR(state, 0644, state_show, state_store);
/*
* wakeup - Report/change current wakeup option for device
*
* Some devices support "wakeup" events, which are hardware signals
* used to activate devices from suspended or low power states. Such
* devices have one of three values for the sysfs power/wakeup file:
*
* + "enabled\n" to issue the events;
* + "disabled\n" not to do so; or
* + "\n" for temporary or permanent inability to issue wakeup.
*
* (For example, unconfigured USB devices can't issue wakeups.)
*
* Familiar examples of devices that can issue wakeup events include
* keyboards and mice (both PS2 and USB styles), power buttons, modems,
* "Wake-On-LAN" Ethernet links, GPIO lines, and more. Some events
* will wake the entire system from a suspend state; others may just
* wake up the device (if the system as a whole is already active).
* Some wakeup events use normal IRQ lines; other use special out
* of band signaling.
*
* It is the responsibility of device drivers to enable (or disable)
* wakeup signaling as part of changing device power states, respecting
* the policy choices provided through the driver model.
*
* Devices may not be able to generate wakeup events from all power
* states. Also, the events may be ignored in some configurations;
* for example, they might need help from other devices that aren't
* active, or which may have wakeup disabled. Some drivers rely on
* wakeup events internally (unless they are disabled), keeping
* their hardware in low power modes whenever they're unused. This
* saves runtime power, without requiring system-wide sleep states.
*/
static const char enabled[] = "enabled";
static const char disabled[] = "disabled";
static ssize_t
wake_show(struct device * dev, struct device_attribute *attr, char * buf)
{
return sprintf(buf, "%s\n", device_can_wakeup(dev)
? (device_may_wakeup(dev) ? enabled : disabled)
: "");
}
static ssize_t
wake_store(struct device * dev, struct device_attribute *attr,
const char * buf, size_t n)
{
char *cp;
int len = n;
if (!device_can_wakeup(dev))
return -EINVAL;
cp = memchr(buf, '\n', n);
if (cp)
len = cp - buf;
if (len == sizeof enabled - 1
&& strncmp(buf, enabled, sizeof enabled - 1) == 0)
device_set_wakeup_enable(dev, 1);
else if (len == sizeof disabled - 1
&& strncmp(buf, disabled, sizeof disabled - 1) == 0)
device_set_wakeup_enable(dev, 0);
else
return -EINVAL;
return n;
}
static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store);
static struct attribute * power_attrs[] = {
&dev_attr_state.attr,
&dev_attr_wakeup.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);
}
