rpio
High performance GPIO/i2c/PWM/SPI module for Raspberry Pi, Orange Pi, Banana Pi
mraa
IO library that helps you use I2c, SPI, gpio, uart, pwm, analog inputs (aio) and more on a number of platforms such as the Intel galileo, the Intel edison and others
rpi-softspi
Software SPI implementation to use any Raspberry Pi pins as a SPI interface