Linux Slave SPI support on Tegra2

I am working Tegra2 embedded on a Toradex T20 module.
Development environment is Linux 3.x. Mainstream Linux 3.x does not cover Slave SPI support,
but drivers/spi/spi_slave_tegra.c, developed by NVIDIA on 2011, covers this issue.
However no information at all is given about this driver usage, test applications and so on.
Any information about spi_slave_tegra.c is welcome.

Thank you for your attention.