[RFC] Kernel API

Hi everyone, I'd like to know how i can get all the Kernel APIs, which i can call ones i need in my Kernel Modules. Sometimes, i wanna use some Kenrel APIS as the userspace i can use 'man api', which i can understand it and use it. But i have not find the way to search a Kernel API easily. Cloud anyone give me some advices? -- Thanks Harry Wei