cpufreq: Support per-policy performance boost
The boost control currently applies to the whole system. However, users
may prefer to boost a subset of cores in order to provide prioritized
performance to workloads running on the boosted cores.
Enable per-policy boost by adding a 'boost' sysfs interface under each
policy path. This can be found at:
/sys/devices/system/cpu/cpufreq/policy<*>/boost
Same to the global boost switch, writing 1/0 to the per-policy 'boost'
enables/disables boost on a cpufreq policy respectively.
The user view of global and per-policy boost controls should be:
1. Enabling global boost initially enables boost on all policies, and
per-policy boost can then be enabled or disabled individually, given that
the platform does support so.
2. Disabling global boost makes the per-policy boost interface illegal.
Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com>
Reviewed-by: Wei Xu <xuwei5@hisilicon.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>