drm/exynos: Add DECON driver

This patch is based on exynos-drm-next branch of Inki Dae's tree at:
git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos.git

DECON(Display and Enhancement Controller) is the new IP
in exynos7 SOC for generating video signals using pixel data.

DECON driver can be used to drive 2 different interfaces on Exynos7:
DECON-INT(video controller) and DECON-EXT(Mixer for HDMI)

The existing FIMD driver code was used as a template to create
DECON driver. Only DECON-INT is supported as of now, and
DECON-EXT support will be added later.

The current version of the driver supports video mode displays.

Changelog v2:
- Change config name, DRM_EXYNOS_DECON to DRM_EXYNOS7_DECON.

Signed-off-by: Akshu Agrawal <akshua@gmail.com>
Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

Documentation/devicetree/bindings/video/exynos7-decon.txt

@@ -0,0 +1,68 @@
+Device-Tree bindings for Samsung Exynos7 SoC display controller (DECON)
+
+DECON (Display and Enhancement Controller) is the Display Controller for the
+Exynos7 series of SoCs which transfers the image data from a video memory
+buffer to an external LCD interface.
+
+Required properties:
+- compatible: value should be "samsung,exynos7-decon";
+
+- reg: physical base address and length of the DECON registers set.
+
+- interrupt-parent: should be the phandle of the decon controller's
+		parent interrupt controller.
+
+- interrupts: should contain a list of all DECON IP block interrupts in the
+		 order: FIFO Level, VSYNC, LCD_SYSTEM. The interrupt specifier
+		 format depends on the interrupt controller used.
+
+- interrupt-names: should contain the interrupt names: "fifo", "vsync",
+	"lcd_sys", in the same order as they were listed in the interrupts
+        property.
+
+- pinctrl-0: pin control group to be used for this controller.
+
+- pinctrl-names: must contain a "default" entry.
+
+- clocks: must include clock specifiers corresponding to entries in the
+         clock-names property.
+
+- clock-names: list of clock names sorted in the same order as the clocks
+               property. Must contain "pclk_decon0", "aclk_decon0",
+	       "decon0_eclk", "decon0_vclk".
+- i80-if-timings: timing configuration for lcd i80 interface support.
+
+Optional Properties:
+- samsung,power-domain: a phandle to DECON power domain node.
+- display-timings: timing settings for DECON, as described in document [1].
+		Can be used in case timings cannot be provided otherwise
+		or to override timings provided by the panel.
+
+[1]: Documentation/devicetree/bindings/video/display-timing.txt
+
+Example:
+
+SoC specific DT entry:
+
+	decon@13930000 {
+		compatible = "samsung,exynos7-decon";
+		interrupt-parent = <&combiner>;
+		reg = <0x13930000 0x1000>;
+		interrupt-names = "lcd_sys", "vsync", "fifo";
+		interrupts = <0 188 0>, <0 189 0>, <0 190 0>;
+		clocks = <&clock_disp PCLK_DECON_INT>,
+			 <&clock_disp ACLK_DECON_INT>,
+			 <&clock_disp SCLK_DECON_INT_ECLK>,
+			 <&clock_disp SCLK_DECON_INT_EXTCLKPLL>;
+		clock-names = "pclk_decon0", "aclk_decon0", "decon0_eclk",
+				"decon0_vclk";
+		status = "disabled";
+	};
+
+Board specific DT entry:
+
+	decon@13930000 {
+		pinctrl-0 = <&lcd_clk &pwm1_out>;
+		pinctrl-names = "default";
+		status = "okay";
+	};

drivers/gpu/drm/exynos/Kconfig

@@ -24,17 +24,24 @@ config DRM_EXYNOS_FIMD
 	help
 	  Choose this option if you want to use Exynos FIMD for DRM.
 
+config DRM_EXYNOS7_DECON
+	bool "Exynos DRM DECON"
+	depends on DRM_EXYNOS
+	select FB_MODE_HELPERS
+	help
+	  Choose this option if you want to use Exynos DECON for DRM.
+
 config DRM_EXYNOS_DPI
 	bool "EXYNOS DRM parallel output support"
-	depends on DRM_EXYNOS_FIMD
+	depends on (DRM_EXYNOS_FIMD || DRM_EXYNOS7_DECON)
 	select DRM_PANEL
 	default n
 	help
 	  This enables support for Exynos parallel output.
 
 config DRM_EXYNOS_DSI
 	bool "EXYNOS DRM MIPI-DSI driver support"
-	depends on DRM_EXYNOS_FIMD
+	depends on (DRM_EXYNOS_FIMD || DRM_EXYNOS7_DECON)
 	select DRM_MIPI_DSI
 	select DRM_PANEL
 	default n
@@ -43,7 +50,7 @@ config DRM_EXYNOS_DSI
 
 config DRM_EXYNOS_DP
 	bool "EXYNOS DRM DP driver support"
-	depends on DRM_EXYNOS_FIMD && ARCH_EXYNOS && (DRM_PTN3460=n || DRM_PTN3460=y || DRM_PTN3460=DRM_EXYNOS)
+	depends on (DRM_EXYNOS_FIMD || DRM_EXYNOS7DECON) && ARCH_EXYNOS && (DRM_PTN3460=n || DRM_PTN3460=y || DRM_PTN3460=DRM_EXYNOS)
 	default DRM_EXYNOS
 	select DRM_PANEL
 	help

drivers/gpu/drm/exynos/Makefile

@@ -10,6 +10,7 @@ exynosdrm-y := exynos_drm_drv.o exynos_drm_encoder.o \
 
 exynosdrm-$(CONFIG_DRM_EXYNOS_IOMMU) += exynos_drm_iommu.o
 exynosdrm-$(CONFIG_DRM_EXYNOS_FIMD)	+= exynos_drm_fimd.o
+exynosdrm-$(CONFIG_DRM_EXYNOS7_DECON)	+= exynos7_drm_decon.o
 exynosdrm-$(CONFIG_DRM_EXYNOS_DPI)	+= exynos_drm_dpi.o
 exynosdrm-$(CONFIG_DRM_EXYNOS_DSI)	+= exynos_drm_dsi.o
 exynosdrm-$(CONFIG_DRM_EXYNOS_DP)	+= exynos_dp_core.o exynos_dp_reg.o