Add output power management protocol

This specifies how to control power management modes of outputs.

Closes: swaywm#56

Makefile

@@ -7,6 +7,7 @@ unstable_protocols = \
 	unstable/wlr-gamma-control-unstable-v1.xml \
 	unstable/wlr-input-inhibitor-unstable-v1.xml \
 	unstable/wlr-layer-shell-unstable-v1.xml \
+	unstable/wlr-output-power-management-v1.xml \
 	unstable/wlr-screencopy-unstable-v1.xml
 
 check:

unstable/wlr-output-power-management-unstable-v1.xml

@@ -0,0 +1,124 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="wlr_output_power_management_unstable_v1">
+  <copyright>
+    Copyright © 2019 Purism SPC
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice (including the next
+    paragraph) shall be included in all copies or substantial portions of the
+    Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+  </copyright>
+
+  <description summary="Control power management modes of outputs">
+    This protocol allows clients to control power management modes
+    of outputs that are currently part of the compositor space. The
+    intent is to allow speial clients like desktop shells to power
+    down outputs when the system is idle.
+
+    To modify outputs not currently part of the compositor space see
+    wlr-output-management.
+
+    Warning! The protocol described in this file is experimental and
+    backward incompatible changes may be made. Backward compatible changes
+    may be added together with the corresponding interface version bump.
+    Backward incompatible changes are done by bumping the version number in
+    the protocol and interface names and resetting the interface version.
+    Once the protocol is to be declared stable, the 'z' prefix and the
+    version number in the protocol and interface names are removed and the
+    interface version number is reset.
+  </description>
+
+  <interface name="zwlr_output_power_management_manager_v1" version="1">
+    <description summary="manager to create per-output power management">
+      This interface is a manager that allows creating per-output power
+      management mode controls.
+    </description>
+
+    <request name="get_output_power_management">
+      <description summary="get a power management for an output">
+        Create a power management mode control that can be used to
+        adjust the power management mode for a given output.
+      </description>
+      <arg name="id" type="new_id" interface="zwlr_output_power_management_v1"/>
+      <arg name="output" type="object" interface="wl_output"/>
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the manager">
+        All objects created by the manager will still remain valid, until their
+        appropriate destroy request has been called.
+      </description>
+    </request>
+
+  </interface>
+  <interface name="zwlr_output_power_management_v1" version="1">
+    <description summary="adjust power save mode for an output">
+      This object offers requests to set the power save mode of an
+      output.
+    </description>
+
+    <enum name="mode">
+      <entry name="off" value="0"
+             summary="Output is turned off."/>
+      <entry name="on" value="1"
+             summary="Output is turned on, no power saving"/>
+    </enum>
+
+    <request name="set_mode">
+      <description summary="Set an outputs power save mode">
+        Set an output's power save mode to the given mode. The mode change
+        is effective immediately. If the output does not support the given
+        mode a failed event is sent.
+      </description>
+      <arg name="mode" type="uint" enum="mode" summary="the power save mode to set"/>
+    </request>
+
+    <event name="mode">
+      <description summary="Report a power save mode change">
+        Report the power save mode change of an output.
+
+        The mode event is sent after an output changed its power save mode. The reason
+        can be a client using set_mode or the compositor deciding to change an output's
+        mode.
+        This event is also sent immediately when the object is created so the clients is
+        informed about the current power save mode.
+      </description>
+      <arg name="mode" type="uint" enum="mode"
+           summary="the output's new power save mode"/>
+    </event>
+
+    <event name="failed">
+      <description summary="object no longer valid">
+        This event indicates that the output power management control
+        is no longer valid. This can happen for a number of reasons,
+        including:
+        - The output doesn't support power management
+        - Another client already has exclusive power management control
+          for this output
+        - The output disapeared
+
+        Upon receiving this event, the client should destroy this object.
+      </description>
+    </event>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy this power management">
+        Destroys the power management mode control object.
+      </description>
+    </request>
+  </interface>
+</protocol>