retroarch has a similar rotate config. However I was researching if you could rotate the linux frame buffer without the emulators having to do it. But it seems it needs rotate support in the kernel to do it:
linux kernel
fbcon=rotate:<n>
This option changes the orientation angle of the console display. The value ‘n’ accepts the following:
0 - normal orientation (0 degree)
1 - clockwise orientation (90 degrees)
2 - upside down orientation (180 degrees)
3 - counterclockwise orientation (270 degrees)
The angle can be changed anytime afterwards by ‘echoing’ the same numbers to any one of the 2 attributes found in /sys/class/graphics/fbcon:
rotate - rotate the display of the active console
rotate_all - rotate the display of all consoles
Console rotation will only become available if Framebuffer Console Rotation support is compiled in your kernel.
NOTE: This is purely console rotation. Any other applications that use the framebuffer will remain at their ‘normal’ orientation. Actually, the underlying fb driver is totally ignorant of console rotation.
ref:
https://www.kernel.org/doc/html/latest/fb/fbcon.html?highlight=rotate
update:
You have to add in linux kernel option to rotate the screen but not sure if it would work in EmuELEC.
CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y