Hi Nandish,
if the ST7789S is not in Linux as a display driver, then you need to add it by yourself. We use the following display module for i.MX boards, it's the same principle. RGB + init interface like I2C or SPI. Maybe you can use the existing implementation as a basis for your own implementation:
https://www.element14.com/community/docs/DOC-68483/l/43-lcd-module-and-adapter-board
Look into the "Documents" and "Download" section.
In following link you find a code snippet which shows the SPI commands for the ST7789: http://www.newhavendisplay.com/app_notes/2-4TFT_ST7789.txt
Data sheet of the ST7789S can be found here: http://www.hpinfotech.ro/ST7789S.pdf
It is also very similar to the display driver ILI9341 (see here 320x240 controller differences ST7789S and ILI9341 [Solved] | AVR Freaks), so overall it shouldn't be a problem to get this done. Except if you don't know how to patch this into Linux :smileycool:
But if you are successful somehow, don't hesitate to post your success story here!
Regards,
Bernhard.
