diff options
Diffstat (limited to 'drivers/base/power/sysfs.c')
| -rw-r--r-- | drivers/base/power/sysfs.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c index 8d04fb435c1..f3a0c562bcb 100644 --- a/drivers/base/power/sysfs.c +++ b/drivers/base/power/sysfs.c @@ -3,6 +3,7 @@ */ #include <linux/device.h> +#include <linux/string.h> #include "power.h" @@ -48,8 +49,81 @@ static ssize_t state_store(struct device * dev, struct device_attribute *attr, c 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 = { |