[IA64] Add ACPI based P-state support

Patch to support P-state transitions on ia64. This driver is based on ACPI,
and uses the ACPI processor driver interface to find out the P-state support
information for the processor. This driver plugs into generic cpufreq
infrastructure.

Once this driver is loaded successfully, ondemand/userspace governor can be
used to change the CPU frequency dynamically based on load or on request from
userspace process.

Refer :
ACPI specification -
      http://www.acpi.info
P-state related PAL calls -
      http://developer.intel.com/design/itanium/downloads/24869909.pdf

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/arch/ia64/kernel/cpufreq/Kconfig b/arch/ia64/kernel/cpufreq/Kconfig
new file mode 100644
index 000000000000..2d9d5279b981
--- /dev/null
+++ b/arch/ia64/kernel/cpufreq/Kconfig
@@ -0,0 +1,29 @@
+
+#
+# CPU Frequency scaling
+#
+
+menu "CPU Frequency scaling"
+
+source "drivers/cpufreq/Kconfig"
+
+if CPU_FREQ
+
+comment "CPUFreq processor drivers"
+
+config IA64_ACPI_CPUFREQ
+        tristate "ACPI Processor P-States driver"
+        select CPU_FREQ_TABLE
+        depends on ACPI_PROCESSOR
+        help
+        This driver adds a CPUFreq driver which utilizes the ACPI
+        Processor Performance States.
+
+        For details, take a look at <file:Documentation/cpu-freq/>.
+
+        If in doubt, say N.
+
+endif   # CPU_FREQ
+
+endmenu
+