ACPI: Notify the _PPC evaluation status to the platform

According to the ACPI spec(section 8.4.4.3) OSPM should convey the _PPC
evaluations status to the platform if there exists the _OST object.
The _OST contains two arguments:
	The first is the PERFORMANCE notificatin event.
	The second is the status of _PPC object.
OSPM will convey the _PPC evaluation status to the platform.
Of course when the module parameter of "ignore_ppc" is added, OSPM won't
evaluate the _PPC object. But it will call the _OST object.

At the same time the _OST object will be evaluated only when the PERFORMANCE
notification event is received.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 47 insertions, 3 deletions

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 8ba0ed0b9ddb..fc1f49bbbeef 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -152,15 +152,59 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
         return 0;
 }
 
-int acpi_processor_ppc_has_changed(struct acpi_processor *pr)
+#define ACPI_PROCESSOR_NOTIFY_PERFORMANCE       0x80
+/*
+ * acpi_processor_ppc_ost: Notify firmware the _PPC evaluation status
+ * @handle: ACPI processor handle
+ * @status: the status code of _PPC evaluation
+ *      0: success. OSPM is now using the performance state specificed.
+ *      1: failure. OSPM has not changed the number of P-states in use
+ */
+static void acpi_processor_ppc_ost(acpi_handle handle, int status)
+{
+        union acpi_object params[2] = {
+                {.type = ACPI_TYPE_INTEGER,},
+                {.type = ACPI_TYPE_INTEGER,},
+        };
+        struct acpi_object_list arg_list = {2, params};
+        acpi_handle temp;
+
+        params[0].integer.value = ACPI_PROCESSOR_NOTIFY_PERFORMANCE;
+        params[1].integer.value =  status;
+
+        /* when there is no _OST , skip it */
+        if (ACPI_FAILURE(acpi_get_handle(handle, "_OST", &temp)))
+                return;
+
+        acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
+        return;
+}
+
+int acpi_processor_ppc_has_changed(struct acpi_processor *pr, int event_flag)
 {
         int ret;
 
-        if (ignore_ppc)
+        if (ignore_ppc) {
+                /*
+                 * Only when it is notification event, the _OST object
+                 * will be evaluated. Otherwise it is skipped.
+                 */
+                if (event_flag)
+                        acpi_processor_ppc_ost(pr->handle, 1);
                 return 0;
+        }
 
         ret = acpi_processor_get_platform_limit(pr);
-
+        /*
+         * Only when it is notification event, the _OST object
+         * will be evaluated. Otherwise it is skipped.
+         */
+        if (event_flag) {
+                if (ret < 0)
+                        acpi_processor_ppc_ost(pr->handle, 1);
+                else
+                        acpi_processor_ppc_ost(pr->handle, 0);
+        }
         if (ret < 0)
                 return (ret);
         else