drm/tilcdc: add support for LCD panels (v5)

Add an output panel driver for LCD panels.  Tested with LCD3 cape on
beaglebone.

v1: original
v2: s/of_find_node_by_name()/of_get_child_by_name()/ from Pantelis
    Antoniou
v3: add backlight support
v4: rebase to latest of video timing helpers
v5: remove some unneeded fields from panel-info struct, add DT bindings
    docs

Signed-off-by: Rob Clark <robdclark@gmail.com>
Tested-by: Koen Kooi <koen@dominion.thruhere.net>

Documentation/devicetree/bindings/drm/tilcdc/panel.txt

@@ -0,0 +1,59 @@
+Device-Tree bindings for tilcdc DRM generic panel output driver
+
+Required properties:
+ - compatible: value should be "ti,tilcdc,panel".
+ - panel-info: configuration info to configure LCDC correctly for the panel
+   - ac-bias: AC Bias Pin Frequency
+   - ac-bias-intrpt: AC Bias Pin Transitions per Interrupt
+   - dma-burst-sz: DMA burst size
+   - bpp: Bits per pixel
+   - fdd: FIFO DMA Request Delay
+   - sync-edge: Horizontal and Vertical Sync Edge: 0=rising 1=falling
+   - sync-ctrl: Horizontal and Vertical Sync: Control: 0=ignore
+   - raster-order: Raster Data Order Select: 1=Most-to-least 0=Least-to-most
+   - fifo-th: DMA FIFO threshold
+ - display-timings: typical videomode of lcd panel.  Multiple video modes
+   can be listed if the panel supports multiple timings, but the 'native-mode'
+   should be the preferred/default resolution.  Refer to
+   Documentation/devicetree/bindings/video/display-timing.txt for display
+   timing binding details.
+
+Recommended properties:
+ - pinctrl-names, pinctrl-0: the pincontrol settings to configure
+   muxing properly for pins that connect to TFP410 device
+
+Example:
+
+	/* Settings for CDTech_S035Q01 / LCD3 cape: */
+	lcd3 {
+		compatible = "ti,tilcdc,panel";
+		pinctrl-names = "default";
+		pinctrl-0 = <&bone_lcd3_cape_lcd_pins>;
+		panel-info {
+			ac-bias           = <255>;
+			ac-bias-intrpt    = <0>;
+			dma-burst-sz      = <16>;
+			bpp               = <16>;
+			fdd               = <0x80>;
+			sync-edge         = <0>;
+			sync-ctrl         = <1>;
+			raster-order      = <0>;
+			fifo-th           = <0>;
+		};
+		display-timings {
+			native-mode = <&timing0>;
+			timing0: 320x240 {
+				hactive         = <320>;
+				vactive         = <240>;
+				hback-porch     = <21>;
+				hfront-porch    = <58>;
+				hsync-len       = <47>;
+				vback-porch     = <11>;
+				vfront-porch    = <23>;
+				vsync-len       = <2>;
+				clock-frequency = <8000000>;
+				hsync-active    = <0>;
+				vsync-active    = <0>;
+			};
+		};
+	};

drivers/gpu/drm/tilcdc/Kconfig

@@ -4,6 +4,9 @@ config DRM_TILCDC
 	select DRM_KMS_HELPER
 	select DRM_KMS_CMA_HELPER
 	select DRM_GEM_CMA_HELPER
+	select OF_VIDEOMODE
+	select OF_DISPLAY_TIMING
+	select BACKLIGHT_CLASS_DEVICE
 	help
 	  Choose this option if you have an TI SoC with LCDC display
 	  controller, for example AM33xx in beagle-bone, DA8xx, or

drivers/gpu/drm/tilcdc/Makefile

@@ -4,6 +4,7 @@ tilcdc-y := \
 	tilcdc_crtc.o \
 	tilcdc_tfp410.o \
 	tilcdc_slave.o \
+	tilcdc_panel.o \
 	tilcdc_drv.o
 
 obj-$(CONFIG_DRM_TILCDC)	+= tilcdc.o

drivers/gpu/drm/tilcdc/tilcdc_drv.c

@@ -21,6 +21,7 @@
 #include "tilcdc_regs.h"
 #include "tilcdc_tfp410.h"
 #include "tilcdc_slave.h"
+#include "tilcdc_panel.h"
 
 #include "drm_fb_helper.h"
 
@@ -589,6 +590,7 @@ static int __init tilcdc_drm_init(void)
 	DBG("init");
 	tilcdc_tfp410_init();
 	tilcdc_slave_init();
+	tilcdc_panel_init();
 	return platform_driver_register(&tilcdc_platform_driver);
 }
 
@@ -597,6 +599,7 @@ static void __exit tilcdc_drm_fini(void)
 	DBG("fini");
 	tilcdc_tfp410_fini();
 	tilcdc_slave_fini();
+	tilcdc_panel_fini();
 	platform_driver_unregister(&tilcdc_platform_driver);
 }