Experience summary of the 8250 driver retrofit

1, copy the existing drive, and then make a partial modification
2, do not have to go too deep into the system kernel-driven call process, distinguish between what needs to be modified, which is the kernel-driven own
3, for the content to be modified, refer to other people's success examples, see what needs to be modified
4, if necessary, the original copy can be first not loaded into the drive, the driver of their own copy loaded into
5, the realization of the function, according to the steps to achieve
6, know the function and function of each module, which is involved in hardware, which is involved in the system, generally speaking, the device, the driver of the registration, generally does not involve the driver, only when the application layer calls the hardware related calls.

7, the transformation of the serial port driver if the external module loading mode, that is, insmod mode, rather than built into the kernel generated vmlinux, you can not use the console driver, or the compilation will appear

Error:redefinition of ' __inittest '/opt/kangear/hello/hello.c:16:note:previous definition of ' __inittest ' was here
Error, there is a redefinition situation.

Experience summary of the 8250 driver retrofit