[PATCH] driver model wakeup flags

This is a refresh of an earlier patch to add "wakeup" support to the
PM core model.  This provides per-device bus-neutral control of the
use of wakeup events.

  * "struct device_pm_info" has two bits that are initialized as
    part of setting up the enclosing struct device:
      - "can_wakeup", reflecting hardware capabilities
      - "may_wakeup", the policy setting (when CONFIG_PM)

  * There's a writeable sysfs "wakeup" file, with one of two values:
      - "enabled", when the policy is to allow wakeup
      - "disabled", when the policy is not to allow it
      - "" if the device can't currently issue wakeups

By default, wakeup is enabled on all devices that support it.  If its
driver doesn't support it ... treat it as a bug.  :)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 73 insertions, 0 deletions

diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 8d04fb435c17..89c57875f3e5 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 = {