Download the user manual/chip manual of the chip, which contains the address and function introduction of each register. Write the corresponding driver according to the required functions, obtain the .ko kernel module file, modify the kernel makefile and other files, reconfigure the kernel, and compile the driver. Before compiling into the kernel, you can use the insmod command to load the driver for debugging. It is possible not to add it to the kernel. Adding insmod xxx.ko to /etc/init.d/rcS can also be loaded at startup