Merge tag 'driver-core-5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the "big" set of driver core patches for 5.5-rc1

  There's a few minor cleanups and fixes in here, but the majority of
  the patches in here fall into two buckets:

   - debugfs api cleanups and fixes

   - driver core device link support for boot dependancy issues

  The debugfs api cleanups are working to slowly refactor the debugfs
  apis so that it is even harder to use incorrectly. That work has been
  happening for the past few kernel releases and will continue over
  time, it's a long-term project/goal

  The driver core device link support missed 5.4 by just a bit, so it's
  been sitting and baking for many months now. It's from Saravana Kannan
  to help resolve the problems that DT-based systems have at boot time
  with dependancy graphs and kernel modules. Turns out that no one has
  actually tried to build a generic arm64 kernel with loads of modules
  and have it "just work" for a variety of platforms (like a distro
  kernel). The big problem turned out to be a lack of dependency
  information between different areas of DT entries, and the work here
  resolves that problem and now allows devices to boot properly, and
  quicker than a monolith kernel.

  All of these patches have been in linux-next for a long time with no
  reported issues"

* tag 'driver-core-5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (68 commits)
  tracing: Remove unnecessary DEBUG_FS dependency
  of: property: Add device link support for interrupt-parent, dmas and -gpio(s)
  debugfs: Fix !DEBUG_FS debugfs_create_automount
  of: property: Add device link support for "iommu-map"
  of: property: Fix the semantics of of_is_ancestor_of()
  i2c: of: Populate fwnode in of_i2c_get_board_info()
  drivers: base: Fix Kconfig indentation
  firmware_loader: Fix labels with comma for builtin firmware
  driver core: Allow device link operations inside sync_state()
  driver core: platform: Declare ret variable only once
  cpu-topology: declare parse_acpi_topology in <linux/arch_topology.h>
  crypto: hisilicon: no need to check return value of debugfs_create functions
  driver core: platform: use the correct callback type for bus_find_device
  firmware_class: make firmware caching configurable
  driver core: Clarify documentation for fwnode_operations.add_links()
  mailbox: tegra: Fix superfluous IRQ error message
  net: caif: Fix debugfs on 64-bit platforms
  mac80211: Use debugfs_create_xul() helper
  media: c8sectpfe: no need to check return value of debugfs_create functions
  of: property: Add device link support for iommus, mboxes and io-channels
  ...

1 files changed, 42 insertions, 0 deletions

diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 9d9dc444d787..8feeb94b8acc 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -17,6 +17,7 @@ struct device;
 struct fwnode_handle {
 	struct fwnode_handle *secondary;
 	const struct fwnode_operations *ops;
+	struct device *dev;
 };
 
 /**
@@ -67,6 +68,44 @@ 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.
  */
 struct fwnode_operations {
 	struct fwnode_handle *(*get)(struct fwnode_handle *fwnode);
@@ -106,6 +145,8 @@ 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)				\
@@ -127,5 +168,6 @@ struct fwnode_operations {
 		if (fwnode_has_op(fwnode, op))				\
 			(fwnode)->ops->op(fwnode, ## __VA_ARGS__);	\
 	} while (false)
+#define get_dev_from_fwnode(fwnode)	get_device((fwnode)->dev)
 
 #endif