Advanced Configuration and Power Interface Specification

ACPI Source Language (ASL)Reference
ReturnType is optional and specifies the type(s) of the object(s) returned by the method. If the
method does not return an object, then nothing is specified or UnknownObj is specified. To specify
a single return type, simply use the ObjectTypeKeyword (e.g. IntObj, PkgObj, etc.). To specify
multiple possible return types, enclose the comma-separated ObjectTypeKeywords with braces. For
example: {IntObj, BuffObj}.
ParameterTypes is optional and specifies the type of the method parameters. It is a commaseparated,
variable-length list of the expected object type or types for each of the method parameters,
enclosed in braces. For each parameter, the parameter type consists of either an ObjectTypeKeyword
or a comma-separated sub-list of ObjectTypeKeywords enclosed in braces. If ParameterTypes is
specified, the number of parameters must match NumArgs.
TermList is a variable-length list of executable ASL statements representing the body of the control
method.
Description
Creates a new control method of name MethodName. This is a named package containing a series of
object references that collectively represent a control method, which is a procedure that can be
invoked to perform computation. Method opens a name scope.
System software executes a control method by referencing the objects in the package in order. For
more information on method execution, see Section 5.5.2, “Control Method Execution.”
The current namespace location used during name creation is adjusted to be the current location on
the namespace tree. Any names created within this scope are “below” the name of this package. The
current namespace location is assigned to the method package, and all namespace references that
occur during control method execution for this package are relative to that location.
If a method is declared as Serialized, an implicit mutex associated with the method object is
acquired at the specified SyncLevel. If no SyncLevel is specified, SyncLevel 0 is assumed. The
serialize rule can be used to prevent reentering of a method. This is especially useful if the method
creates namespace objects. Without the serialize rule, the reentering of a method will fail when it
attempts to create the same namespace object.
There are eight local variables automatically available for each method, referenced as Local0
through Local7. These locals may be used to store any type of ASL object.
Also notice that all namespace objects created by a method have temporary lifetime. When method
execution exits, the created objects will be destroyed.
Examples
The following block of ASL sample code shows a use of Method for defining a control method that
turns on a power resource.
Method (_ON) {
Store (One, GIO.IDEP)
Sleep (10)
Store (One, GIO.IDER)
Stall (10)
Store (Zero, GIO.IDEI)
}
// assert power
// wait 10ms
// de-assert reset#
// wait 10us
// de-assert isolation
This method is an implementation of _SRS (Set Resources). It shows the use of a method argument
and two method locals.
Version 6.0 863