From e2ae9bcc4aaacda04edb75c4eea93384719efaa5 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Wed, 4 Sep 2019 14:11:21 -0700 Subject: driver core: Add support for linking devices during device addition The firmware corresponding to a device (dev.fwnode) might be able to provide functional dependency information between a device and its supplier and consumer devices. Tracking this functional dependency allows optimizing device probe order and informing a supplier when all its consumers have probed (and thereby actively managing their resources). The existing device links feature allows tracking and using supplier-consumer relationships. So, this patch adds the add_links() fwnode callback to allow firmware to create device links for each device as the device is added. However, when consumer devices are added, they might not have a supplier device to link to despite needing mandatory resources/functionality from one or more suppliers. A waiting_for_suppliers list is created to track such consumers and retry linking them when new devices get added. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20190904211126.47518-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- include/linux/fwnode.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'include/linux/fwnode.h') diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h index d8c6d231d577..6ae05b9ce359 100644 --- a/include/linux/fwnode.h +++ b/include/linux/fwnode.h @@ -66,6 +66,21 @@ 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. If some suppliers are not + * yet available, 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 suppliers of this device or if the supplier information is + * not known. Return an error if and only if the supplier + * information is known but some of the suppliers are not yet + * available to create device links to. */ struct fwnode_operations { struct fwnode_handle *(*get)(struct fwnode_handle *fwnode); @@ -103,6 +118,8 @@ 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, + struct device *dev); }; #define fwnode_has_op(fwnode, op) \ -- cgit v1.2.3-59-g8ed1b