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