Is it possible to change gpu and memory frequencies using the open source Radeon driver?

English Hardware
1

My card is slightly factory overclocked and I want to set it back to Amd reference.

2

Hi
Maybe rovclock?
http://www.hasw.net/linux/

3

Wow, that’s old.

Radeon 7500
Radeon 8500
Radeon 9000
Radeon 9100
Radeon 9500 (Pro)
Radeon 9550
Radeon 9600
Mobility FireGL T2
Mobility Radeon 9600 M10
Radeon 9700 (Pro)
Radeon X800XL

My card is an HD 7870.

Gonna check it out anyway.