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AML_EVALNODE(9)          BSD Kernel Developer's Manual         AML_EVALNODE(9)

     aml_evalnode, aml_evalname, aml_find_node, aml_freevalue, aml_val2int --
     AML API

     #include <&lt;dev/acpi/acpireg.h>&gt;
     #include <&lt;dev/acpi/acpivar.h>&gt;
     #include <&lt;dev/acpi/acpidev.h>&gt;
     #include <&lt;dev/acpi/amltypes.h>&gt;
     #include <&lt;dev/acpi/dsdt.h>&gt;

     aml_evalnode(struct acpi_softc *sc, struct aml_node *node, int argc,
         struct aml_value *argv, struct aml_value *res);

     aml_evalname(struct acpi_softc *sc, struct aml_node *parent,
         const char *name, int argc, struct aml_value *argv,
         struct aml_value *res);

     aml_find_node(struct aml_node *node, const char *name,
         int (*cbproc)(struct aml_node *, void *arg), void *arg);

     aml_freevalue(struct aml_value *val);

     aml_val2int(struct aml_value *rval);

     The AML API handles decoding and evaluation of the AML code embedded in a
     machine's ACPI tables.  This code is used to implement configuration and
     control mechanisms for machines.

     aml_evalnode() evaluates the AML node node located in the ACPI table
     specified by sc.  Parameters may be passed using the argv parameters with
     the parameter argc specifying the number of parameters passed.  If there
     are no arguments, a value of 0 is used for argc and argv should be NULL.
     If evaluating the node produces any result, for example a string with a
     device name reference, this result is stored in the res parameter unless
     it is NULL.  res is cleared before storing the result.  If node does not
     exist, aml_evalnode() returns ACPI_E_BADVALUE, otherwise it returns 0.

     aml_evalname() is similar to aml_evalnode() but differs in that it
     searches for a subnode of parent with the name name.  If such a node is
     found, it is evaluated using aml_evalnode(), passing whatever parameters
     were passed to itself.  aml_evalname() returns the return value of

     aml_find_node() is used to find all subnodes of parent with a name of
     name.  For each node found, the function specified as the cbproc parame-
     ter is called with the node and arg as the first and second parameters,
     respectively.  The function specified as the cbproc parameter returns a
     value that specifies if the tree walk should be terminated (!0) or con-
     tinued (0) with the children.  aml_find_node() always returns 0.

     aml_freevalue() is used to free up the result returned from
     aml_evalnode() or the other AML evaluation functions.  Note that no
     attempt is made to free the struct aml_value itself so it is safe to
     allocate this on the stack.  Also, calling aml_freevalue() with a parame-
     ter of NULL is not an error.

     aml_val2int() is used to convert the struct aml_value pointed to by the
     rval parameter to a signed 64-bit integer value.  Multiple types exist
     for struct aml_value, and the conversion value depends on the type of the
     value object as follows.  For objects of type AML_OBJTYPE_INTEGER and
     AML_OBJTYPE_STATICINT, the return value is simply the integer value
     stored in the object.  For objects of type AML_OBJTYPE_BUFFER, the return
     value is the integer interpretation of the buffer contents.  For objects
     of type AML_OBJTYPE_STRING, the return value is the integer value repre-
     sented as a string in base 10 or, if prefixed by ``0x'', in base 16.  If
     rval is NULL or not of one of the types mentioned above, aml_val2int()
     returns 0.

     Using aml_evalname() to invoke the ``_STA'' method on a node node should
     be done like the following:

           struct acpi_softc       *sc
           struct aml_node         *node;
           struct aml_value        res;

           if (aml_evalname(sc->sc_acpi, node, "_STA", 0, NULL, &res) != 0) {
                   dnprintf(10, "%s: no _STA\n", DEVNAME(sc));

     Using the struct aml_value obtained from the ``_STA'' call to determine
     if the device is a battery is done as follows:

           if ((aml_val2int(&res) & STA_BATTERY) == 0) {
                   dnprintf(10, %s: no battery present\n", DEVNAME(sc));

     Finally, when the result stored in res is no longer needed, free it using


     acpi(4), acpidump(8)

     The AML API was written by Jordan Hargrave <jordan@openbsd.org>.

BSD                            January 21, 2014                            BSD