PM: Introduce library for device-specific OPPs (v7)

SoCs have a standard set of tuples consisting of frequency and
voltage pairs that the device will support per voltage domain. These
are called Operating Performance Points or OPPs. The actual
definitions of OPP varies over silicon versions. For a specific domain,
we can have a set of {frequency, voltage} pairs. As the kernel boots
and more information is available, a default set of these are activated
based on the precise nature of device. Further on operation, based on
conditions prevailing in the system (such as temperature), some OPP
availability may be temporarily controlled by the SoC frameworks.

To implement an OPP, some sort of power management support is necessary
hence this library depends on CONFIG_PM.

Contributions include:
Sanjeev Premi for the initial concept:
	http://patchwork.kernel.org/patch/50998/
Kevin Hilman for converting original design to device-based.
Kevin Hilman and Paul Walmsey for cleaning up many of the function
abstractions, improvements and data structure handling.
Romit Dasgupta for using enums instead of opp pointers.
Thara Gopinath, Eduardo Valentin and Vishwanath BS for fixes and
cleanups.
Linus Walleij for recommending this layer be made generic for usage
in other architectures beyond OMAP and ARM.
Mark Brown, Andrew Morton, Rafael J. Wysocki, Paul E. McKenney for
valuable improvements.

Discussions and comments from:
http://marc.info/?l=linux-omap&m=126033945313269&w=2
http://marc.info/?l=linux-omap&m=125482970102327&w=2
http://marc.info/?t=125809247500002&r=1&w=2
http://marc.info/?l=linux-omap&m=126025973426007&w=2
http://marc.info/?t=128152609200064&r=1&w=2
http://marc.info/?t=128468723000002&r=1&w=2
incorporated.

v1: http://marc.info/?t=128468723000002&r=1&w=2

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 14 insertions, 0 deletions

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index e45894c696e..29bff6117ab 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -245,3 +245,17 @@ config PM_OPS
         bool
         depends on PM_SLEEP || PM_RUNTIME
         default y
+
+config PM_OPP
+        bool "Operating Performance Point (OPP) Layer library"
+        depends on PM
+        ---help---
+          SOCs have a standard set of tuples consisting of frequency and
+          voltage pairs that the device will support per voltage domain. This
+          is called Operating Performance Point or OPP. The actual definitions
+          of OPP varies over silicon within the same family of devices.
+
+          OPP layer organizes the data internally using device pointers
+          representing individual voltage domains and provides SOC
+          implementations a ready to use framework to manage OPPs.
+          For more information, read <file:Documentation/power/opp.txt>