ACPI, cpuidle: Clarify C-state description in sysfs

Add a new sysfs entry under cpuidle states. desc - can be used by driver to
communicate to userspace any specific information about the state.
This helps in identifying the exact hardware C-states behind the ACPI C-state
definition.

Idea is to export this through powertop, which will help to map the C-state
reported by powertop to actual hardware C-state.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index cdc8004..06480bc 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -32,9 +32,11 @@
 #define DOMAIN_COORD_TYPE_SW_ANY	0xfd
 #define DOMAIN_COORD_TYPE_HW_ALL	0xfe
 
-#define ACPI_CSTATE_SYSTEMIO	(0)
-#define ACPI_CSTATE_FFH		(1)
-#define ACPI_CSTATE_HALT	(2)
+#define ACPI_CSTATE_SYSTEMIO	0
+#define ACPI_CSTATE_FFH		1
+#define ACPI_CSTATE_HALT	2
+
+#define ACPI_CX_DESC_LEN	32
 
 /* Power Management */
 
@@ -74,6 +76,7 @@
 	u64 time;
 	struct acpi_processor_cx_policy promotion;
 	struct acpi_processor_cx_policy demotion;
+	char desc[ACPI_CX_DESC_LEN];
 };
 
 struct acpi_processor_power {