Hong Kong VISA entry into China

Hello,

If I get a working permit in Hong Kong, does it allow me unlimited entry to and from mainland China as well or just Hong Kong? For example am I able to go back and fourth between Hong Kong and Shenzhen or even further, go from Shanghai to Thailand and back as often as I want?

My concern is getting Hong Kong's and making trips from mainland China to other Asian countries and back into mainland China without running into problems or being denied entry.

Thanks,

Brandon