Many simple RGB panels use a MIPI DBI interface over SPI, so this patch adds support for this interface using an API compatible with Linux.
The MIPI DBI interface works similar to SPI using 8-bit words in the format of: COMMAND DATA1 DATA2 ... However the interface has two variations on this.
The first variation is implemented by this patch series: Using 9-bit words, with the first bit signalling whether the word is a COMMAND or DATA.
The second variation is not implemented by this series: A GPIO is held at a value during an 8-bit word to indicate if it's a COMMAND or WORD. Adding support for this wouldn't be too hard, but I don't have any hardware to test it on.
Linux seems to not implement the specification correctly: It sets CS inactive between words instead of keeping it active for the entire transaction. I'm copying this behaviour to keep compatibility in porting panels across from the kernel.
Signed-off-by: John Watts contact@jookia.org --- John Watts (5): spi: Return old wordlen in spit_set_wordlen spi: Limit spi_set_wordlen to SPI_DEFAULT_WORDLEN spi: Implement spi_set_wordlen for driver model spi: softspi: Support setting wordlen video: add support for MIPI DBI interface
drivers/spi/soft_spi.c | 7 +++++ drivers/spi/spi-uclass.c | 29 +++++++++++++++++++ drivers/spi/spi.c | 6 ++-- drivers/video/Kconfig | 6 ++++ drivers/video/Makefile | 1 + drivers/video/mipi_dbi.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++ include/mipi_dbi.h | 73 ++++++++++++++++++++++++++++++++++++++++++++++++ include/spi.h | 2 +- 8 files changed, 191 insertions(+), 3 deletions(-) --- base-commit: c0ea27bccfb7d2d37fd36806ac2a2f7389099420 change-id: 20240601-mipi_dbi-aeda98f2f9d5
Best regards,