ACPI: document method tracing hooks

Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 29 insertions, 0 deletions

diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX
index 299615d821ac..161edbcf905e 100644
--- a/Documentation/00-INDEX
+++ b/Documentation/00-INDEX
@@ -14,6 +14,7 @@ Following translations are available on the WWW:
         - this file.
 ABI/
         - info on kernel <-> userspace ABI and relative interface stability.
+
 BUG-HUNTING
         - brute force method of doing binary search of patches to find bug.
 Changes
@@ -66,6 +67,8 @@ VGA-softcursor.txt
         - how to change your VGA cursor from a blinking underscore.
 accounting/
         - documentation on accounting and taskstats.
+acpi/
+        - info on ACPI-specific hooks in the kernel.
 aoe/
         - description of AoE (ATA over Ethernet) along with config examples.
 applying-patches.txt
diff --git a/Documentation/acpi/method-tracing.txt b/Documentation/acpi/method-tracing.txt
new file mode 100644
index 000000000000..f6efb1ea559a
--- /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".