What Device Deriver Developers Do?

Hello, I've read some books (Linux Device Drivers, or Linux Kernel Development) OK, So now I know a little bit more about linux internals.. Yeah, I thought I should know about the hardware to develop device driver. because I'm interested in hdd and ssd, so I tried to read ATA specification. but I don't understand EVERY sentence of that document... Is there something I'm missing, like I should learn electronic circuit first...? Did I try too tough thing as newbie? Or is there a good entrypoint for developing device driver? Thank you, Any tiny advice will be so much helpful...! Hyeonggon.