Hardware datasheets/technical documentation

Hello All,
I am an independent developer based in India, deeply interested in writing device drivers for Haiku, in the storage hardware realm.
Can anyone tell me how I can go about procuring datasheets/technical documentation, for writing device drivers? (I am a beginner in this area, and would appreciate any guidance).
What documentation would I need, in order to implement a device driver ?
Is it only a datasheet, or do I need anything else?

Please advise,
thanks a lot,

Our fearless leader once wrote an introduction to device writting:

Another still-online site is BeDrivers.com:
In particular, this article from Be Inc’s great newsletters time:

Speaking of Be Inc., you should find very interresting articles and hints in their Developer Library : Drivers section still avaible thanks to mirror(s):

You could also find some good drivers sample-code under your BeOS’s /optional/sample-code/drivers.
Many drivers available on BeBits.com (http://www.bebits.com/browse/14) comes with source.

And last but not least, BeDrivers.com offer a mailing-list for BeOS drivers development talks. Haiku mailing-lists can also help you…

PS: for what kind of storage device?
Whenever, you can’t have enough datasheet(s) when you want to write device drivers :wink: