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authorSaravana Kannan <saravanak@google.com>2019-09-04 14:11:21 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-10-04 17:29:50 +0200
commite2ae9bcc4aaacda04edb75c4eea93384719efaa5 (patch)
tree9c01d02d0a1e67c4de38c94e27180f9411fc850d /include/linux/fwnode.h
parent372a67c0c5ef63f55bd1eb480d9555328d8ec0f2 (diff)
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 <saravanak@google.com> Link: https://lore.kernel.org/r/20190904211126.47518-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/fwnode.h')
-rw-r--r--include/linux/fwnode.h17
1 files changed, 17 insertions, 0 deletions
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) \