Add infrastructure to be able to modify the cpu_power of each core

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
 arch/arm/include/asm/topology.h |    2 ++
 arch/arm/kernel/topology.c      |   36 +++++++++++++++++++++++++++++++++++-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h
index 58b8b84..78e4c85 100644
--- a/arch/arm/include/asm/topology.h
+++ b/arch/arm/include/asm/topology.h

@@ -27,11 +27,13 @@ void init_cpu_topology(void);

 void store_cpu_topology(unsigned int cpuid);
 const struct cpumask *cpu_coregroup_mask(int cpu);

+void set_power_scale(unsigned int cpu, unsigned long power);
 #else

 static inline void init_cpu_topology(void) { }
 static inline void store_cpu_topology(unsigned int cpuid) { }

+static inline void set_power_scale(unsigned int cpu, unsigned long power) { }
 #endif

 #include <asm-generic/topology.h>

diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
index 8200dea..00301a7 100644
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c

@@ -22,6 +22,35 @@

 #include <asm/cputype.h>
 #include <asm/topology.h>

+/*
+ * cpu power scale management
+ */
+
+/*
+ * cpu power table
+ * This per cpu data structure describes the relative capacity of each core.
+ * On a heteregenous system, cores don't have the same computation capacity
+ * and we reflect that difference in the cpu_power field so the scheduler can
+ * take this difference into account for load balance. A per cpu structure is
+ * preferred because each cpu is mainly using its own cpu_power even it's not
+ * always true because of nohz_idle_balance