How to config the SPI work as slave

VIM3
1

How to config the SPI work as slave？

3

For 4.9 kernel seems not support SPI slave mode, for mainline kernel seems support, you can check yourself.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/drivers/spi/spi-slave-system-control.c?h=v5.12-rc7