What kind of visa do I need to apply for short stay (visit) to Hong Kong?

I am Australian citizen and plan to stay for 5 days in Hong Kong and then head to India and also in return from India in 2 months I plan to stay overnight in Hong Kong and head back to Australia.
So in return journey will I be eligible to get a visitor entry permit in or will the same visa which I first get for 90 days be enough to stay in Hong Kong on my way back