Spindle control by SPI digital potentiometer

Hello everybody. I don´t know much about electronic systems so I am looking for some guidance. Me and some friends are converting a Sherline benchtop lathe to CNC. We plan to use a RPi with a CNC breakout board. So far we have been able to control the steppers but not the spindle. Originally, the spindle is controlled manually by a KBIC-240D DC motor speed controller. This board controls the spindle by means of a manual potentiometer and a lever switch. We are replacing the manual potentiometer with a digital one, especifically a MCP4131. However, this
potentiometer is controlled only by SPI communication protocol and as I understand it the default HAL file only sends PWM signal through the designated pin. 

How can I configure the HAL file so that the RPi can establish SPI communication with the potentiometer?