ARM: multi-cluster PM: secondary kernel entry code

CPUs in cluster based systems, such as big.LITTLE, have special needs
when entering the kernel due to a hotplug event, or when resuming from
a deep sleep mode.

This is vectorized so multiple CPUs can enter the kernel in parallel
without serialization.

The mcpm prefix stands for "multi cluster power management", however
this is usable on single cluster systems as well.  Only the basic
structure is introduced here.  This will be extended with later patches.

In order not to complexify things more than they currently have to,
the planned work to make runtime adjusted MPIDR based indexing and
dynamic memory allocation for cluster states is postponed to a later
cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions
should be sufficient for those systems expected to be available in the
near future.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2c3bdce15134..2d17275b5df2 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1599,6 +1599,14 @@ config HAVE_ARM_TWD
         help
           This options enables support for the ARM timer and watchdog unit
 
+config MCPM
+        bool "Multi-Cluster Power Management"
+        depends on CPU_V7 && SMP
+        help
+          This option provides the common power management infrastructure
+          for (multi-)cluster based systems, such as big.LITTLE based
+          systems.
+
 choice
         prompt "Memory split"
         default VMSPLIT_3G