drm/tilcdc: add encoder slave (v2)

Add output panel driver for i2c encoder slaves.

v1: original
v2: add DT bindings docs, and minor updates for review comments

Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Koen Kooi <koen@dominion.thruhere.net>

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

@@ -0,0 +1,18 @@
+Device-Tree bindings for tilcdc DRM encoder slave output driver
+
+Required properties:
+ - compatible: value should be "ti,tilcdc,slave".
+ - i2c: the phandle for the i2c device the encoder slave is connected to
+
+Recommended properties:
+ - pinctrl-names, pinctrl-0: the pincontrol settings to configure
+   muxing properly for pins that connect to TFP410 device
+
+Example:
+
+	hdmi {
+		compatible = "ti,tilcdc,slave";
+		i2c = <&i2c0>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&nxp_hdmi_bonelt_pins>;
+	};

drivers/gpu/drm/tilcdc/Makefile

@@ -3,6 +3,7 @@ ccflags-y := -Iinclude/drm -Werror
 tilcdc-y := \
 	tilcdc_crtc.o \
 	tilcdc_tfp410.o \
+	tilcdc_slave.o \
 	tilcdc_drv.o
 
 obj-$(CONFIG_DRM_TILCDC)	+= tilcdc.o

drivers/gpu/drm/tilcdc/tilcdc_drv.c

@@ -20,6 +20,7 @@
 #include "tilcdc_drv.h"
 #include "tilcdc_regs.h"
 #include "tilcdc_tfp410.h"
+#include "tilcdc_slave.h"
 
 #include "drm_fb_helper.h"
 
@@ -587,17 +588,19 @@ static int __init tilcdc_drm_init(void)
 {
 	DBG("init");
 	tilcdc_tfp410_init();
+	tilcdc_slave_init();
 	return platform_driver_register(&tilcdc_platform_driver);
 }
 
 static void __exit tilcdc_drm_fini(void)
 {
 	DBG("fini");
 	tilcdc_tfp410_fini();
+	tilcdc_slave_fini();
 	platform_driver_unregister(&tilcdc_platform_driver);
 }
 
-module_init(tilcdc_drm_init);
+late_initcall(tilcdc_drm_init);
 module_exit(tilcdc_drm_fini);
 
 MODULE_AUTHOR("Rob Clark <robdclark@gmail.com");