driver core: Redefine the meaning of fwnode_operations.add_links()

Change the meaning of fwnode_operations.add_links() to just create
fwnode links by parsing the properties of a given fwnode.

This patch doesn't actually make any code changes. To keeps things more
digestable, the actual functional changes come in later patches in this
series.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20201121020232.908850-12-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/firmware/efi/efi-init.c

@@ -316,7 +316,7 @@ static struct device_node *find_pci_overlap_node(void)
  * resource reservation conflict on the memory window that the efifb
  * framebuffer steals from the PCIe host bridge.
  */
-static int efifb_add_links(const struct fwnode_handle *fwnode,
+static int efifb_add_links(struct fwnode_handle *fwnode,
 			   struct device *dev)
 {
 	struct device_node *sup_np;

include/linux/fwnode.h

@@ -78,44 +78,8 @@ struct fwnode_reference_args {
  *			       endpoint node.
  * @graph_get_port_parent: Return the parent node of a port node.
  * @graph_parse_endpoint: Parse endpoint for port and endpoint id.
- * @add_links:	Called after the device corresponding to the fwnode is added
- *		using device_add(). The function is expected to create device
- *		links to all the suppliers of the device that are available at
- *		the time this function is called.  The function must NOT stop
- *		at the first failed device link if other unlinked supplier
- *		devices are present in the system.  This is necessary for the
- *		driver/bus sync_state() callbacks to work correctly.
- *
- *		For example, say Device-C depends on suppliers Device-S1 and
- *		Device-S2 and the dependency is listed in that order in the
- *		firmware.  Say, S1 gets populated from the firmware after
- *		late_initcall_sync().  Say S2 is populated and probed way
- *		before that in device_initcall(). When C is populated, if this
- *		add_links() function doesn't continue past a "failed linking to
- *		S1" and continue linking C to S2, then S2 will get a
- *		sync_state() callback before C is probed. This is because from
- *		the perspective of S2, C was never a consumer when its
- *		sync_state() evaluation is done. To avoid this, the add_links()
- *		function has to go through all available suppliers of the
- *		device (that corresponds to this fwnode) and link to them
- *		before returning.
- *
- *		If some suppliers are not yet available (indicated by an error
- *		return value), this function will be called again when other
- *		devices are added to allow creating device links to any newly
- *		available suppliers.
- *
- *		Return 0 if device links have been successfully created to all
- *		the known suppliers of this device or if the supplier
- *		information is not known.
- *
- *		Return -ENODEV if the suppliers needed for probing this device
- *		have not been registered yet (because device links can only be
- *		created to devices registered with the driver core).
- *
- *		Return -EAGAIN if some of the suppliers of this device have not
- *		been registered yet, but none of those suppliers are necessary
- *		for probing the device.
+ * @add_links:	Create fwnode links to all the suppliers of the fwnode. Return
+ *		zero on success, a negative error code otherwise.
  */
 struct fwnode_operations {
 	struct fwnode_handle *(*get)(struct fwnode_handle *fwnode);
@@ -155,7 +119,7 @@ struct fwnode_operations {
 	(*graph_get_port_parent)(struct fwnode_handle *fwnode);
 	int (*graph_parse_endpoint)(const struct fwnode_handle *fwnode,
 				    struct fwnode_endpoint *endpoint);
-	int (*add_links)(const struct fwnode_handle *fwnode,
+	int (*add_links)(struct fwnode_handle *fwnode,
 			 struct device *dev);
 };