clocksource/cadence_ttc: Overhaul clocksource frequency adjustment
The currently used method adjusting the clocksource to a changing input
frequency does not work on kernels from 3.11 on.
The new approach is to keep the timer frequency as constant as possible.
I.e.
- due to the TTC's prescaler limitations, allow frequency changes
only if the frequency scales by a power of 2
- adjust the counter's divider on the fly when a frequency change
occurs
This limits cpufreq to scale by certain factors only.
But we may keep the time base somewhat constant, so that sleep() & co
keep working as expected, while supporting cpufreq.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>
1 file changed