/*
* drivers/base/power/sysfs.c - sysfs entries for device PM
*/
#include <linux/device.h>
#include <linux/string.h>
#include <linux/pm_runtime.h>
#include "power.h"
/*
* control - Report/change current runtime PM setting of the device
*
* Runtime power management of a device can be blocked with the help of
* this attribute. All devices have one of the following two values for
* the power/control file:
*
* + "auto\n" to allow the device to be power managed at run time;
* + "on\n" to prevent the device from being power managed at run time;
*
* The default for all devices is "auto", which means that devices may be
* subject to automatic power management, depending on their drivers.
* Changing this attribute to "on" prevents the driver from power managing
* the device at run time. Doing that while the device is suspended causes
* it to be woken up.
*
* 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.
*
* async - Report/change current async suspend setting for the device
*
* Asynchronous suspend and resume of the device during system-wide power
* state transitions can be enabled by writing "enabled" to this file.
* Analogously, if "disabled" is written to this file, the device will be
* suspended and resumed synchronously.
*
* All devices have one of the following two values for power/async:
*
* + "enabled\n" to permit the asynchronous suspend/resume of the device;
* + "disabled\n" to forbid it;
*
* NOTE: It generally is unsafe to permit the asynchronous suspend/resume
* of a device unless it is certain that all of the PM dependencies of the
* device are known to the PM core. However, for some devices this
* attribute is set to "enabled" by bus type code or device drivers and in
* that cases it should be safe to leave the default value.
*/
static const char enabled[] = "enabled";
static const char disabled[] = "disabled";
#ifdef CONFIG_PM_RUNTIME
static const char ctrl_auto[] = "auto";
static const char ctrl_on[] = "on";
static ssize_t control_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%s\n",
dev->power.runtime_auto ? ctrl_auto : ctrl_on);
}
static ssize_t control_store(struct device * dev, struct device_attribute *attr,
const char * buf, size_t n)
{
char *cp;
int len = n;
cp = memchr(buf, '\n', n);
if (cp)
len = cp - buf;
if (len == sizeof ctrl_auto - 1 && strncmp(buf, ctrl_auto, len) == 0)
pm_runtime_allow(dev);
else if (len == sizeof ctrl_on - 1 && strncmp(buf, ctrl_on, len) == 0)
pm_runtime_forbid(dev);
else
return -EINVAL;
return n;
}
static DEVICE_ATTR(control, 0644, control_show, control_store);
#endif
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);
#ifdef CONFIG_PM_SLEEP_ADVANCED_DEBUG
static ssize_t async_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%s\n",
device_async_suspend_enabled(dev) ? enabled : disabled);
}
static ssize_t async_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t n)
{
char *cp;
int len = n;
cp = memchr(buf, '\n', n);
if (cp)
len = cp - buf;
if (len == sizeof enabled - 1 && strncmp(buf, enabled, len) == 0)
device_enable_async_suspend(dev);
else if (len == sizeof disabled - 1 && strncmp(buf, disabled, len) == 0)
device_disable_async_suspend(dev);
else
return -EINVAL;
return n;
}
static DEVICE_ATTR(async, 0644, async_show, async_store);
#endif /* CONFIG_PM_SLEEP_ADVANCED_DEBUG */
static struct attribute * power_attrs[] = {
#ifdef CONFIG_PM_RUNTIME
&dev_attr_control.attr,
#endif
&dev_attr_wakeup.attr,
#ifdef CONFIG_PM_SLEEP_ADVANCED_DEBUG
&dev_attr_async.attr,
#endif
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);
}
