Qualcomm QCA639x is a family of WiFi + Bluetooth chips, with BT part being controlled through the UART and WiFi being present on PCIe bus. Both blocks share common power sources wich should be turned on before either of devices can be probed. Declare common 'qca639x' driver providing a power domain to be used by both BT and WiFi parts. While it would be easy to just add power supplies to BT device tree node, for WiFi it is not that easy. The chip has to be powered on before the PCIe bus is probed (otherwise it will be left undetected). Adding power supplies to the PCIe device nodes would require changes to the host controller driver. Thus it is supposed to be simpler to provide power domain via separate driver. Changes since v1: - Moved the driver from drivers/mfd to drivers/misc - Fixed compatibility string in device binding - Removed debug messages
