ACPI: document method tracing hooks
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/Documentation/acpi/method-tracing.txt b/Documentation/acpi/method-tracing.txt
new file mode 100644
index 0000000..f6efb1e
--- /dev/null
+++ b/Documentation/acpi/method-tracing.txt
@@ -0,0 +1,26 @@
+/sys/module/acpi/parameters/:
+
+trace_method_name
+ The AML method name that the user wants to trace
+
+trace_debug_layer
+ The temporary debug_layer used when tracing the method.
+ Using 0xffffffff by default if it is 0.
+
+trace_debug_level
+ The temporary debug_level used when tracing the method.
+ Using 0x00ffffff by default if it is 0.
+
+trace_state
+ The status of the tracing feature.
+
+ "enabled" means this feature is enabled
+ and the AML method is traced every time it's executed.
+
+ "1" means this feature is enabled and the AML method
+ will only be traced during the next execution.
+
+ "disabled" means this feature is disabled.
+ Users can enable/disable this debug tracing feature by
+ "echo string > /sys/module/acpi/parameters/trace_state".
+ "string" should be one of "enable", "disable" and "1".
