ACPI / CPPC: Add a CPUFreq driver for use with CPPC

This driver utilizes the methods introduced in a previous
patch titled - "ACPI: Introduce CPU performance controls using CPPC"
and enables usage with existing CPUFreq governors.

Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Reviewed-by: Al Stone <al.stone@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/Kconfig.arm

@@ -227,3 +227,20 @@ config ARM_PXA2xx_CPUFREQ
 	  This add the CPUFreq driver support for Intel PXA2xx SOCs.
 
 	  If in doubt, say N.
+
+config ACPI_CPPC_CPUFREQ
+	tristate "CPUFreq driver based on the ACPI CPPC spec"
+	depends on ACPI
+	select ACPI_CPPC_LIB
+	default n
+	help
+	  This adds a CPUFreq driver which uses CPPC methods
+	  as described in the ACPIv5.1 spec. CPPC stands for
+	  Collaborative Processor Performance Controls. It
+	  is based on an abstract continuous scale of CPU
+	  performance values which allows the remote power
+	  processor to flexibly optimize for power and
+	  performance. CPPC relies on power management firmware
+	  support for its operation.
+
+	  If in doubt, say N.