If it is an academic project then it depends on the scope. Are you trying to rewrite the serial drivers? For a printer "driver" you can just open the serial port, do whatever serial communications are necessary and then close the port.
If you really need to write a serial driver, check the kernel code (kernel.org) under drivers/serial - it's all there.
If you just need to talk to the printer using the serial port, you don't need a driver. It can be done from user space. Here's a good starting point:
You will also need the full specification for the printer