Huh ? It happened that I just heard of it a month of ago. Actually, it is not called "China return home permit" but I do know what you meant.
You must be talking about a special kind (unlimited re-entry) of visa (normally 10 years) for those Hong Kong born of Chinese decent Actually a friend of mine used similiar phase and it puzzled me for a while in trying to understand what she was referring to by "China return home".
I accompanied a friend of mine who is a Hong Kong local to get hers last month from CTS (China ? Travel Service) in Wanchai. You probably can get it from any CTS location. That is the place where you normally get your vista to China.
Hope that it is the thing that you are looking for.
1) Note firstly that a passport is a travel document for travelling between NATIONS.
As between HK and mainland- these are two parts of the same country CHina- you shouldn't use a passport if you are Chinese
And in your case, you hold the HKSAR passport- which means you are Chinese- you should use the "Home permit" instead
2) As to whether you can use HKSAR passport to enter mainland China from 3rd countries:
* NO- you should use Home Permit
* The Home Permit can only be applied for through the CTS in Hongkong or Macao
* If you are overseas, you can apply for a "TRAVEL PASS OF THE PEOPLE"S REPUBLIC OF CHINA" (which is a substitute for a Chinese passport)
* You may think this is "unfair" to Hong kong Chinese, as mainland Chinese can use their ordinary Chinese passports to come to HK from 3rd countries (as a stop in the middle of their trip back to the mainland)-
Note however that this is treated as TRANSIT, NOT ENTRY;
* If you travel to and from 3rd countries, and transit through CHina (mainland), without entering the mainland-- then you can use your HKSAR passport.