staging: drm/imx: Add LDB support

This adds support for the LVDS Display Bridge contained
in i.MX5 and i.MX6 SoCs.

Bit mapping, data width, and video timings are configurable
via device tree. Dual-channel mode is supported for a single
high-resolution source.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/staging/imx-drm/ldb.txt

+Device-Tree bindings for LVDS Display Bridge (ldb)
+
+LVDS Display Bridge
+===================
+
+The LVDS Display Bridge device tree node contains up to two lvds-channel
+nodes describing each of the two LVDS encoder channels of the bridge.
+
+Required properties:
+ - #address-cells : should be <1>
+ - #size-cells : should be <0>
+ - compatible : should be "fsl,imx53-ldb" or "fsl,imx6q-ldb".
+                Both LDB versions are similar, but i.MX6 has an additional
+                multiplexer in the front to select any of the four IPU display
+                interfaces as input for each LVDS channel.
+ - gpr : should be <&gpr> on i.MX53 and i.MX6q.
+         The phandle points to the iomuxc-gpr region containing the LVDS
+         control register.
+- clocks, clock-names : phandles to the LDB divider and selector clocks and to
+                        the display interface selector clocks, as described in
+                        Documentation/devicetree/bindings/clock/clock-bindings.txt
+        The following clocks are expected on i.MX53:
+                "di0_pll" - LDB LVDS channel 0 mux
+                "di1_pll" - LDB LVDS channel 1 mux
+                "di0" - LDB LVDS channel 0 gate
+                "di1" - LDB LVDS channel 1 gate
+                "di0_sel" - IPU1 DI0 mux
+                "di1_sel" - IPU1 DI1 mux
+        On i.MX6q the following additional clocks are needed:
+                "di2_sel" - IPU2 DI0 mux
+                "di3_sel" - IPU2 DI1 mux
+        The needed clock numbers for each are documented in
+        Documentation/devicetree/bindings/clock/imx5-clock.txt, and in
+        Documentation/devicetree/bindings/clock/imx6q-clock.txt.
+
+Optional properties:
+ - pinctrl-names : should be "default" on i.MX53, not used on i.MX6q
+ - pinctrl-0 : a phandle pointing to LVDS pin settings on i.MX53,
+               not used on i.MX6q
+ - fsl,dual-channel : boolean. if it exists, only LVDS channel 0 should
+   be configured - one input will be distributed on both outputs in dual
+   channel mode
+
+LVDS Channel
+============
+
+Each LVDS Channel has to contain a display-timings node that describes the
+video timings for the connected LVDS display. For detailed information, also
+have a look at Documentation/devicetree/bindings/video/display-timing.txt.
+
+Required properties:
+ - reg : should be <0> or <1>
+ - crtcs : a list of phandles with index pointing to the IPU display interfaces
+           that can be used as video source for this channel.
+ - fsl,data-mapping : should be "spwg" or "jeida"
+                      This describes how the color bits are laid out in the
+                      serialized LVDS signal.
+ - fsl,data-width : should be <18> or <24>
+
+example:
+
+gpr: iomuxc-gpr@53fa8000 {
+	/* ... */
+};
+
+ldb: ldb@53fa8008 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	compatible = "fsl,imx53-ldb";
+	gpr = <&gpr>;
+	clocks = <&clks 122>, <&clks 120>,
+		 <&clks 115>, <&clks 116>,
+		 <&clks 123>, <&clks 85>;
+	clock-names = "di0_pll", "di1_pll",
+		      "di0_sel", "di1_sel",
+		      "di0", "di1";
+
+	lvds-channel@0 {
+		reg = <0>;
+		crtcs = <&ipu 0>;
+		fsl,data-mapping = "spwg";
+		fsl,data-width = <24>;
+
+		display-timings {
+			/* ... */
+		};
+	};
+
+	lvds-channel@1 {
+		reg = <1>;
+		crtcs = <&ipu 1>;
+		fsl,data-mapping = "spwg";
+		fsl,data-width = <24>;
+
+		display-timings {
+			/* ... */
+		};
+	};
+};

drivers/staging/imx-drm/Kconfig

@@ -30,6 +30,14 @@ config DRM_IMX_TVE
 	  Choose this to enable the internal Television Encoder (TVe)
 	  found on i.MX53 processors.
 
+config DRM_IMX_LDB
+	tristate "Support for LVDS displays"
+	depends on DRM_IMX
+	select OF_VIDEOMODE
+	help
+	  Choose this to enable the internal LVDS Display Bridge (LDB)
+	  found on i.MX53 and i.MX6 processors.
+
 config DRM_IMX_IPUV3_CORE
 	tristate "IPUv3 core support"
 	depends on DRM_IMX

drivers/staging/imx-drm/Makefile

@@ -5,6 +5,7 @@ obj-$(CONFIG_DRM_IMX) += imxdrm.o
 
 obj-$(CONFIG_DRM_IMX_PARALLEL_DISPLAY) += parallel-display.o
 obj-$(CONFIG_DRM_IMX_TVE) += imx-tve.o
+obj-$(CONFIG_DRM_IMX_LDB) += imx-ldb.o
 obj-$(CONFIG_DRM_IMX_FB_HELPER) += imx-fbdev.o
 obj-$(CONFIG_DRM_IMX_IPUV3_CORE) += ipu-v3/
 obj-$(CONFIG_DRM_IMX_IPUV3)	+= ipuv3-crtc.o