doc: Add Battery Provider API doc

This patch add the documentation of the Battery Provider which lets
external clients feed battery information to BlueZ if they are able to
decode battery reporting via any profile. BlueZ UI clients can then use
the org.bluez.Battery1 API as a single source of battery information
coming from many different profiles.

Reviewed-by: Miao-chen Chou <mcchou@chromium.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/doc/battery-api.txt b/doc/battery-api.txt
index dc7dbeda2..9a6b4fd39 100644
--- a/doc/battery-api.txt
+++ b/doc/battery-api.txt
@@ -12,3 +12,58 @@ Object path	[variable prefix]/{hci0,hci1,...}/dev_XX_XX_XX_XX_XX_XX
 Properties	byte Percentage [readonly]
 
 			The percentage of battery left as an unsigned 8-bit integer.
+
+		string Source [readonly, optional, experimental]
+
+			Describes where the battery information comes from
+			This property is informational only and may be useful
+			for debugging purposes.
+			Providers from BatteryProvider1 may make use of this
+			property to indicate where the battery report comes from
+			(e.g. "HFP 1.7", "HID", or the profile UUID).
+
+
+Battery Provider Manager hierarchy
+==================================
+A battery provider starts by registering itself as a battery provider with the
+RegisterBatteryProvider method passing an object path as the provider ID. Then,
+it can start exposing org.bluez.BatteryProvider1 objects having the path
+starting with the given provider ID. It can also remove objects at any time.
+The objects and their properties exposed by battery providers will be reflected
+on org.bluez.Battery1 interface.
+
+BlueZ will stop monitoring these exposed and removed objects after
+UnregisterBatteryProvider is called for that provider ID.
+
+Service		org.bluez
+Interface	org.bluez.BatteryProviderManager1 [experimental]
+Object path	/org/bluez/{hci0,hci1,...}
+
+Methods		void RegisterBatteryProvider(object provider)
+
+			This registers a battery provider. A registered
+			battery provider can then expose objects with
+			org.bluez.BatteryProvider1 interface described below.
+
+		void UnregisterBatteryProvider(object provider)
+
+			This unregisters a battery provider. After
+			unregistration, the BatteryProvider1 objects provided
+			by this client are ignored by BlueZ.
+
+
+Battery Provider hierarchy
+==========================
+
+Service		<client D-Bus address>
+Interface	org.bluez.BatteryProvider1 [experimental]
+Object path	{provider_root}/{unique battery object path}
+
+Properties	Objects provided on this interface contain the same properties
+		as org.bluez.Battery1 interface. Additionally, this interface
+		needs to have the Device property indicating the object path
+		of the device this battery provides.
+
+		object Device [readonly]
+
+			The object path of the device that has this battery.