Determined empirically, no documentation is available.

The OLPC XO-1.75 laptop used parent 1, that one being VCTCXO/4 (65MHz), but
thought it's a VCTCXO/2 (130MHz). The mmp2 timer driver, not knowing
what is going on, ended up just dividing the rate as of
commit f36797ee ("ARM: mmp/mmp2: dt: enable the clock")'

Link: https://lore.kernel.org/r/20191218190454.420358-3-lkundrak@v3.skSigned-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Olof Johansson <olof@lixom.net>