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/*
* drivers/base/power/sysfs.c - sysfs entries for device PM
*/
#include <linux/device.h>
#include <linux/string.h>
#include "power.h"
#ifdef CONFIG_PM_SYSFS_DEPRECATED
/**
* state - Control current power state of device
*
* show() returns the current power state of the device. '0' indicates
* the device is on. Other values (2) indicate the device is in some low
* power state.
*
* store() sets the current power state, which is an integer valued
* 0, 2, or 3. Devices with bus.suspend_late(), or bus.resume_early()
* methods fail this operation; those methods couldn't be called.
* Otherwise,
*
* - If the recorded dev->power.power_state.event matches the
* target value, nothing is done.
* - If the recorded event code is nonzero, the device is reactivated
* by calling bus.resume() and/or class.resume().
* - If the target value is nonzero, the device is suspended by
* calling class.suspend() and/or bus.suspend() with event code
* PM_EVENT_SUSPEND.
*
* This mechanism is DEPRECATED and should only be used for testing.
*/
static ssize_t state_show(struct device * dev, struct device_attribute *attr, char * buf)
{
if (dev->power.power_state.event)
return sprintf(buf, "2\n");
else
return sprintf(buf, "0\n");
}
static ssize_t state_store(struct device * dev, struct device_attribute *attr, const char * buf, size_t n)
{
pm_message_t state;
int error = -EINVAL;
/* disallow incomplete suspend sequences */
if (dev->bus && (dev->bus->suspend_late || dev->bus->resume_early))
return error;
state.event = PM_EVENT_SUSPEND;
/* Older apps expected to write "3" here - confused with PCI D3 */
if ((n == 1) && !strcmp(buf, "3"))
error = dpm_runtime_suspend(dev, state);
if ((n == 1) && !strcmp(buf, "2"))
error = dpm_runtime_suspend(dev, state);
if ((n == 1) && !strcmp(buf, "0")) {
dpm_runtime_resume(dev);
error = 0;
}
return error ? error : n;
}
static DEVICE_ATTR(state, 0644, state_show, state_store);
#endif /* CONFIG_PM_SYSFS_DEPRECATED */
/*
* 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[] = {
#ifdef CONFIG_PM_SYSFS_DEPRECATED
&dev_attr_state.attr,
#endif
&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);
}
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