Hello,
There are program examples in CW4NET for ARM. These examples contain .h files for eSDHC and qSPI. Use the following path:
C:\Freescale\CW4NET_v2020.06\CW_ARMv8\ARMv8\CodeWarrior_Examples
Unfortunately there isn't available a simple SPI c code, the available information can be found in the u-boot spi drivers or the linux driver according to the LSDKUG.