ACPI / bus: Make ACPI_HANDLE() work for non-GPL code again

Due to commit db3e50f3 (device property: Get rid of struct
fwnode_handle type field), ACPI_HANDLE() inadvertently became
a GPL-only call. The call path that led to that was:

ACPI_HANDLE()
    ACPI_COMPANION()
        to_acpi_device_node()
            is_acpi_device_node()
                acpi_device_fwnode_ops
                    DECLARE_ACPI_FWNODE_OPS(acpi_device_fwnode_ops);

...and the new DECLARE_ACPI_FWNODE_OPS() includes
EXPORT_SYMBOL_GPL, whereas previously it was a static struct.

In order to avoid changing any of that, let's instead provide ever
so slightly better encapsulation of those struct fwnode_operations
instances. Those do not really need to be directly used in
inline function calls in header files. Simply moving two small
functions (is_acpi_device_node and is_acpi_data_node) out of
acpi_bus.h, and into a .c file, does that.

That leaves the internals of struct fwnode_operations as GPL-only
(which I think was the intent all along), but un-breaks any driver
code out there that relies on the ACPI subsystem's being (historically)
an EXPORT_SYMBOL-usable system. By that, I mean, ACPI_HANDLE() and
other basic ACPI calls were non-GPL-protected.

Also, while I'm there, remove a tiny bit of redundancy that was missed
in the earlier commit, by having is_acpi_node() use the other two
routines, instead of checking fwnode directly.

Fixes: db3e50f3 (device property: Get rid of struct fwnode_handle type field)
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/property.c

@@ -1293,3 +1293,16 @@ static int acpi_fwnode_graph_parse_endpoint(const struct fwnode_handle *fwnode,
 DECLARE_ACPI_FWNODE_OPS(acpi_device_fwnode_ops);
 DECLARE_ACPI_FWNODE_OPS(acpi_data_fwnode_ops);
 const struct fwnode_operations acpi_static_fwnode_ops;
+
+bool is_acpi_device_node(const struct fwnode_handle *fwnode)
+{
+	return !IS_ERR_OR_NULL(fwnode) &&
+		fwnode->ops == &acpi_device_fwnode_ops;
+}
+EXPORT_SYMBOL(is_acpi_device_node);
+
+bool is_acpi_data_node(const struct fwnode_handle *fwnode)
+{
+	return !IS_ERR_OR_NULL(fwnode) && fwnode->ops == &acpi_data_fwnode_ops;
+}
+EXPORT_SYMBOL(is_acpi_data_node);

include/acpi/acpi_bus.h

@@ -399,17 +399,12 @@ extern const struct fwnode_operations acpi_device_fwnode_ops;
 extern const struct fwnode_operations acpi_data_fwnode_ops;
 extern const struct fwnode_operations acpi_static_fwnode_ops;
 
+bool is_acpi_device_node(const struct fwnode_handle *fwnode);
+bool is_acpi_data_node(const struct fwnode_handle *fwnode);
+
 static inline bool is_acpi_node(const struct fwnode_handle *fwnode)
 {
-	return !IS_ERR_OR_NULL(fwnode) &&
-		(fwnode->ops == &acpi_device_fwnode_ops
-		 || fwnode->ops == &acpi_data_fwnode_ops);
-}
-
-static inline bool is_acpi_device_node(const struct fwnode_handle *fwnode)
-{
-	return !IS_ERR_OR_NULL(fwnode) &&
-		fwnode->ops == &acpi_device_fwnode_ops;
+	return (is_acpi_device_node(fwnode) || is_acpi_data_node(fwnode));
 }
 
 #define to_acpi_device_node(__fwnode)					\
@@ -422,11 +417,6 @@ static inline bool is_acpi_device_node(const struct fwnode_handle *fwnode)
 			NULL;						\
 	})
 
-static inline bool is_acpi_data_node(const struct fwnode_handle *fwnode)
-{
-	return !IS_ERR_OR_NULL(fwnode) && fwnode->ops == &acpi_data_fwnode_ops;
-}
-
 #define to_acpi_data_node(__fwnode)					\
 	({								\
 		typeof(__fwnode) __to_acpi_data_node_fwnode = __fwnode;	\