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path: root/drivers/base/power/sysfs.c
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Diffstat (limited to 'drivers/base/power/sysfs.c')
-rw-r--r--drivers/base/power/sysfs.c73
1 files changed, 73 insertions, 0 deletions
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 8d04fb435c1..89c57875f3e 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -48,8 +48,81 @@ 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 = {