drm/rockchip: support backlight device

Change-Id: Ib793b0dec8fe62027ca8e3085089d2e431b59eb5
Signed-off-by: Mark Yao <mark.yao@rock-chips.com>

Author: Mark Yao

Documentation/devicetree/bindings/display/rockchip/rockchip-backlight.txt

@@ -0,0 +1,29 @@
+Rockchip DRM backlight device
+================================
+
+Rockchip display controller(see VOP bindings[0]) support CABC function,
+and the CABC function required using VOP self pwm to control backlight,
+This backlight device manager the backlight PWM, auto select correct
+PWM for backlight.
+
+Required properties:
+- compatible: Should be "rockchip,drm-backlight"
+
+Other properties are same to commom PWM backlight bindings[1].
+
+[0]: Documentation/devicetree/bindings/display/rockchip/rockchip-vop.txt
+[1]: Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
+
+example:
+
+backlight {
+	compatible = "rockchip,drm-backlight";
+	pwms = <&pwm 0 5000000>;
+
+	brightness-levels = <0 4 8 16 32 64 128 255>;
+	default-brightness-level = <6>;
+
+	power-supply = <&vdd_bl_reg>;
+	enable-gpios = <&gpio 58 0>;
+};
+

Documentation/devicetree/bindings/display/rockchip/rockchip-drm.txt

@@ -12,6 +12,7 @@ Required properties:
   Documentation/devicetree/bindings/display/rockchip/rockchip-vop.txt
 
 Optional properties
+- backlight: spacial backlight required by cabc function.
 - clocks: include clock specifiers corresponding to entries in the
           clock-names property.
 - clock-names: optional include
@@ -25,6 +26,7 @@ example:
 display-subsystem {
 	compatible = "rockchip,display-subsystem";
 	ports = <&vopl_out>, <&vopb_out>;
+	backlight = <&backlight>
 	clocks = <&cru PLL_VPLL>, <&cru PLL_CPLL>;
 	clock-names = "hdmi-tmds-pll", "default-vop-pll";
 };

drivers/gpu/drm/rockchip/Kconfig

@@ -88,3 +88,11 @@ config ROCKCHIP_DRM_TVE
 	help
 	  Choose this option to enable support for Rockchip TVE controllers.
 	  say Y to enable its driver.
+
+config ROCKCHIP_DRM_BACKLIGHT
+	tristate "Rockchip DRM Backlight"
+	depends on DRM_ROCKCHIP
+	help
+	  This selects support for Rockchip backlight manager,
+	  Vop cabc function request using vop self pwm devices, needed a
+	  unique backlight devices to manager vop and soc pwm devices.

drivers/gpu/drm/rockchip/Makefile

@@ -15,5 +15,6 @@ obj-$(CONFIG_ROCKCHIP_ANALOGIX_DP) += analogix_dp-rockchip.o
 obj-$(CONFIG_ROCKCHIP_INNO_HDMI) += inno_hdmi.o
 obj-$(CONFIG_ROCKCHIP_LVDS) += rockchip_lvds.o
 
+obj-$(CONFIG_ROCKCHIP_DRM_BACKLIGHT) += rockchip_drm_backlight.o
 obj-$(CONFIG_DRM_ROCKCHIP) += rockchip_vop_reg.o rockchipdrm.o
 obj-$(CONFIG_ROCKCHIP_DRM_TVE) += rockchip_drm_tve.o