How to use SPI1 on Pin-Header 2 (rock pi s v1.3)?

I set /boot/uEnv.txt:
verbosity=7
fdtfile=rockchip/rk3308-rock-pi-s.dtb
console=ttyS0,1500000n8
overlays=rk3308-uart0 rk3308-i2c1 rk3308-spi-spidev
param_spidev_spi_bus=1
rootuuid=513ebcfa-a901-4300-9829-68632c397250
initrdsize=0x64d777
kernelversion=4.4.143-57-rockchip-g4b8d0571d76e
initrdimg=initrd.img-4.4.143-57-rockchip-g4b8d0571d76e
kernelimg=vmlinuz-4.4.143-57-rockchip-g4b8d0571d76e

/**

  • Initialise SPI_context without any board configuration, selects a bus and a mux.
  • @param bus Bus to use as listed by spidev
  • @param cs Chip select to use as listed in spidev ???
  • @return Spi context or NULL
    */
    mraa_spi_context mraa_spi_init_raw(unsigned int bus, unsigned int cs);

question:
param cs is the number of bus? or the number of pin? or the number of gpio?

Firstly, The configuration for SPI1 is right. And you will see device /dev/spidevX.Y.

overlays=rk3308-uart0 rk3308-i2c1 rk3308-spi-spidev
param_spidev_spi_bus=1

Secondly, so far the mraa (provided by package libmraa) for ROCK Pi S supports pin header 1 but not pin header 2.