Define and add Generic PM domains (genpd) for CPU clusters. Many new
SoCs group CPUs as clusters. Clusters share common resources like power
rails, caches, VFP, Coresight etc. When all CPUs in the cluster are
idle, these shared resources may also be put in their idle state.

CPUs may be associated with their domain providers. The domains in
turn may be associated with their providers. This is clean way to model
the cluster hierarchy like that of ARM's big.little architecture.

Platform drivers may initialize generic PM domains and setup the CPU PM
domains for the genpd and attach CPUs to the domain. In the following
patches, the CPUs are hooked up to runtime PM framework which helps
power down the domain, when all the CPUs in the domain are idle.

Cc: Ulf Hansson <redacted>
Suggested-by: Kevin Hilman <khilman@kernel.org>
Signed-off-by: Lina Iyer <redacted>
---
 drivers/base/power/Makefile      |   2 +-
 drivers/base/power/cpu_domains.c | 192 +++++++++++++++++++++++++++++++++++++++
 include/linux/cpu_domains.h      |  48 ++++++++++
 3 files changed, 241 insertions(+), 1 deletion(-)
 create mode 100644 drivers/base/power/cpu_domains.c
 create mode 100644 include/linux/cpu_domains.h

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 5998c53..ee383f1 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile

@@ -2,7 +2,7 @@ obj-$(CONFIG_PM)        += sysfs.o generic_ops.o common.o qos.o runtime.o wakeirq.o
 obj-$(CONFIG_PM_SLEEP) += main.o wakeup.o
 obj-$(CONFIG_PM_TRACE_RTC)     += trace.o
 obj-$(CONFIG_PM_OPP)   += opp/
-obj-$(CONFIG_PM_GENERIC_DOMAINS)       +=  domain.o domain_governor.o
+obj-$(CONFIG_PM_GENERIC_DOMAINS)       += domain.o domain_governor.o cpu_domains.o