Hello!
I was also accepted to those same classes this summer, so I looked up the professor teaching 21-127 for the AP/EA students that summer and I actually found all the course material from last year!
Here’s the course website: http://math.cmu.edu/~aremondt/teaching/
He also has the course schedule and syllabus from last year on there, which I doubt should change much this year. If you want to get ahead I guess you could also look at the notes he has posted on there as well.
As for 15-122, my course schedule didn’t give me a professor so I could only find course data from Spring 2018 (http://www.cs.cmu.edu/~15122/), but I’ll keep watching the schedule for any updates.
Good luck, I hope we get to work together this summer!