drm/panel: db7430: Add driver for Samsung DB7430

This adds a new driver for the Samsung DB7430 DPI display
controller as controlled over SPI.

Right now the only panel product we know that is using this
display controller is the LMS397KF04 but there may be more.

This is the first regular panel driver making use of the
MIPI DBI helper library. The DBI "device" portions can not
be used because that code assumes the use of a single
regulator and specific timings around the reset pulse that
do not match the DB7430 datasheet.

Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Doug Anderson <dianders@chromium.org>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210610220527.366432-1-linus.walleij@linaro.org

MAINTAINERS

@@ -5857,6 +5857,13 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/display/panel/raydium,rm67191.yaml
 F:	drivers/gpu/drm/panel/panel-raydium-rm67191.c
 
+DRM DRIVER FOR SAMSUNG DB7430 PANELS
+M:	Linus Walleij <linus.walleij@linaro.org>
+S:	Maintained
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+F:	Documentation/devicetree/bindings/display/panel/samsung,lms397kf04.yaml
+F:	drivers/gpu/drm/panel/panel-samsung-db7430.c
+
 DRM DRIVER FOR SITRONIX ST7703 PANELS
 M:	Guido Günther <agx@sigxcpu.org>
 R:	Purism Kernel Team <kernel@puri.sm>

drivers/gpu/drm/panel/Kconfig

@@ -343,6 +343,16 @@ config DRM_PANEL_RONBO_RB070D30
 	  Say Y here if you want to enable support for Ronbo Electronics
 	  RB070D30 1024x600 DSI panel.
 
+config DRM_PANEL_SAMSUNG_DB7430
+	tristate "Samsung DB7430-based DPI panels"
+	depends on OF && SPI && GPIOLIB
+	depends on BACKLIGHT_CLASS_DEVICE
+	select DRM_MIPI_DBI
+	help
+	  Say Y here if you want to enable support for the Samsung
+	  DB7430 DPI display controller used in such devices as the
+	  LMS397KF04 480x800 DPI panel.
+
 config DRM_PANEL_SAMSUNG_S6D16D0
 	tristate "Samsung S6D16D0 DSI video mode panel"
 	depends on OF

drivers/gpu/drm/panel/Makefile

@@ -33,6 +33,7 @@ obj-$(CONFIG_DRM_PANEL_RASPBERRYPI_TOUCHSCREEN) += panel-raspberrypi-touchscreen
 obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM67191) += panel-raydium-rm67191.o
 obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM68200) += panel-raydium-rm68200.o
 obj-$(CONFIG_DRM_PANEL_RONBO_RB070D30) += panel-ronbo-rb070d30.o
+obj-$(CONFIG_DRM_PANEL_SAMSUNG_DB7430) += panel-samsung-db7430.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6D16D0) += panel-samsung-s6d16d0.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E3HA2) += panel-samsung-s6e3ha2.o