drivers: mipi_dbi: add support for parallel 8080/6800 modes using GPIO

Introduce GPIO-based driver for MIPI DBI class that allows MIPI DBI
type A and B displays to be used on general platforms.

Since each data pin GPIO can be selected individually, the bus pins are
set in a loop, which has a significant negative impact on performance.
When using 8-bit mode and all the data GPIO pins are on the same port,
a look-up table is generated to set the whole port at once as a
performance optimization. This creates a RAM overhead of about 1 kiB.

Tested 8-bit 8080 mode with ILI9486 display on nRF52840-DK board.

Signed-off-by: Stefan Gloor <code@stefan-gloor.ch>

doc/hardware/peripherals/mipi_dbi.rst

@@ -20,7 +20,8 @@ MIPI DBI defines 3 interface types:
 
   #. 8 write clocks per byte. Command/data selected via GPIO pin
 
-Currently, the API only supports Type C controllers, options 1 and 3.
+Currently, the API does not support Type C controllers with 16 write clocks
+(option 2).
 
 API Reference
 *************

drivers/mipi_dbi/CMakeLists.txt

@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 zephyr_sources_ifdef(CONFIG_MIPI_DBI_SPI mipi_dbi_spi.c)
+zephyr_sources_ifdef(CONFIG_MIPI_DBI_GPIO mipi_dbi_gpio.c)
 zephyr_sources_ifdef(CONFIG_MIPI_DBI_SMARTBOND mipi_dbi_smartbond.c)
 zephyr_sources_ifdef(CONFIG_MIPI_DBI_NXP_LCDIC mipi_dbi_nxp_lcdic.c)
 zephyr_sources_ifdef(CONFIG_MIPI_DBI_NXP_FLEXIO_LCDIF mipi_dbi_nxp_flexio_lcdif.c)

drivers/mipi_dbi/Kconfig

@@ -22,6 +22,7 @@ config MIPI_DBI_INIT_PRIORITY
 	  MIPI-DBI Host Controllers initialization priority.
 
 source "drivers/mipi_dbi/Kconfig.spi"
+source "drivers/mipi_dbi/Kconfig.gpio"
 source "drivers/mipi_dbi/Kconfig.smartbond"
 source "drivers/mipi_dbi/Kconfig.nxp_lcdic"
 source "drivers/mipi_dbi/Kconfig.nxp_flexio_lcdif"

drivers/mipi_dbi/Kconfig.gpio

@@ -0,0 +1,12 @@
+# Copyright 2024 Stefan Gloor
+# SPDX-License-Identifier: Apache-2.0
+
+config MIPI_DBI_GPIO
+	bool "MIPI DBI GPIO driver"
+	default y
+	depends on DT_HAS_ZEPHYR_MIPI_DBI_GPIO_ENABLED
+	select GPIO
+	help
+	  Enable support for MIPI DBI GPIO driver. This driver implements
+	  a MIPI-DBI mode A and B compatible controller using GPIO.
+