Passport US

I am flying from US to Beijing and connecting to Shanghai the same day. Upon arrival to Shanghai I will apply for 144 hour twov but will only be in Shanghai for 48 hours. From Shanghai I will fly to Hong Kong. I will spend 48 hours in Hong Kong. From Hong Kong fly back to Beijing and only be there less than 48 hours returning back to USA. Will a 144 hour twov be ok? Does the Visa reset because of my visit to Hong Kong? Do I get my entry permit from Beijing or Shanghai upon arrival to China?

Itinerary:
US>Beijiing>Shanghai (48 hours)
Shanghai>Hong Kong (48 hours)
Hong Kong>Beijing (less than 48 hours)
Beijing>USA