DEPRECATED
Checkout this better one by Hackpascal: https://github.com/hackpascal/ufprog
Simple CH347 SPI-NOR programmer
SPI-NOR programmer software for WCH CH347 USB 2.0 High-speed USB to UART+SPI+I2C bridge using libusb.
Based on ch341prog by Hackpascal.
Tested under linux. It should work under Windows with winusb driver installed but I haven't tried it yet.
Performance
The maximum SPI frequency supported by this chip is 60MHz and it can achieve a read speed of about 4950KB/s.
Pretty impressive for a 32CNY board :)