ACPI: thinkpad-acpi: wakeup on hotunplug reporting

Handle some HKEY events that the firmware uses to report the reason for a
wake up, and to also notify that the system could go back to sleep (if it
woke up just to eject something from the bay, or to undock).

The driver will report the reason of the last wake up in the sysfs
attribute "wakeup_reason": 0 for "none, unknown, or standard ACPI wake up
event", 1 for "bay ejection request" and 2 for "undock request".

The firmware will also report if the operation that triggered the wake up
has been completed, by issuing an HKEY 0x3003 or 0x4003 event.  If the
operation fails, no event is sent.  When such a hotunplug sucessfull
notification is issued, the driver sets the attribute
"wakeup_hotunplug_complete" to 1.

While the firmware does tell us whether we are waking from a suspend or
hibernation scenario, the Linux way of hibernating makes this information
not reliable, and therefore it is not reported.

The idea is that if any of these attributes are non-zero, userspace might
want to do something at the end of the "wake up from sleep" procedures,
such as offering to send the machine back into sleep as soon as it is safe
to do so.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index 3fb864733ca1..9d08e472ef74 100644
--- a/Documentation/thinkpad-acpi.txt
+++ b/Documentation/thinkpad-acpi.txt
@@ -325,6 +325,21 @@ sysfs notes:
                 May return -EPERM (write access locked out by module
                 parameter) or -EACCES (read-only).
 
+        wakeup_reason:
+                Set to 1 if the system is waking up because the user
+                requested a bay ejection.  Set to 2 if the system is
+                waking up because the user requested the system to
+                undock.  Set to zero for normal wake-ups or wake-ups
+                due to unknown reasons.
+
+        wakeup_hotunplug_complete:
+                Set to 1 if the system was waken up because of an
+                undock or bay ejection request, and that request
+                was sucessfully completed.  At this point, it might
+                be useful to send the system back to sleep, at the
+                user's choice.  Refer to HKEY events 0x4003 and
+                0x3003, below.
+
 input layer notes:
 
 A Hot key is mapped to a single input layer EV_KEY event, possibly
@@ -475,6 +490,15 @@ Non hot-key ACPI HKEY event map:
 The above events are not propagated by the driver, except for legacy
 compatibility purposes when hotkey_report_mode is set to 1.
 
+0x2304          System is waking up from suspend to undock
+0x2305          System is waking up from suspend to eject bay
+0x2404          System is waking up from hibernation to undock
+0x2405          System is waking up from hibernation to eject bay
+
+The above events are never propagated by the driver.
+
+0x3003          Bay ejection (see 0x2x05) complete, can sleep again
+0x4003          Undocked (see 0x2x04), can sleep again
 0x5010          Brightness level changed (newer Lenovo BIOSes)
 
 The above events are propagated by the driver.