These 2 head files both locate in "user/include/hw/".

QNX SPI framework shows that application should use spi-master.h, it provide APIs like spi_open/spi_read/spi_write... 
Currently I implement a test app include spi-master.h, and my spi driver works well.

I'm little confused, when should we use spi.h? (i saw it just declare a func list)

I would greatly appreciate it if you could solve the puzzle!