power: zynqmp: Add power domain driver for ZynqMP

Driver should be enabled by CONFIG_POWER_DOMAIN=y and
CONFIG_ZYNQMP_POWER_DOMAIN=y. Power domain driver doesn't have own DT node
but it uses zynqmp firmware DT node that's why there is a need to bind
driver when firmware node is found.

Driver itself is simple. It is sending pmufw config object overlay for
enabling access to device which is done in ...domain_request().
In ...domain_on() capabilities are passed and node is requested.
This should be bare minimum of required to get power domain driver working.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Link: https://lore.kernel.org/r/f4b9433b91c0b18c375b061c7a4e29d428f70547.1644226055.git.michal.simek@xilinx.com
diff --git a/drivers/power/domain/Kconfig b/drivers/power/domain/Kconfig
index 9aea5fc..93d2599 100644
--- a/drivers/power/domain/Kconfig
+++ b/drivers/power/domain/Kconfig
@@ -88,4 +88,13 @@
 	help
 	  Generic power domain implementation for TI K3 devices.
 
+config ZYNQMP_POWER_DOMAIN
+	bool "Enable the Xilinx ZynqMP Power domain driver"
+	depends on POWER_DOMAIN && ZYNQMP_FIRMWARE
+	help
+	  Generic power domain implementation for Xilinx ZynqMP devices.
+	  The driver should be enabled when system starts in very minimal
+	  configuration and it is extended at run time. Then enabling
+	  the driver will ensure that PMUFW enable access to requested IP.
+
 endmenu