driver core: fw_devlink: Handle suppliers that don't use driver core

Device links only work between devices that use the driver core to match
and bind a driver to a device. So, add an API for frameworks to let the
driver core know that a fwnode has been initialized by a driver without
using the driver core.

Then use this information to make sure that fw_devlink doesn't make the
consumers wait indefinitely on suppliers that'll never bind to a driver.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210205222644.2357303-6-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/core.c

@@ -1636,6 +1636,17 @@ static int fw_devlink_create_devlink(struct device *con,
 
 	sup_dev = get_dev_from_fwnode(sup_handle);
 	if (sup_dev) {
+		/*
+		 * If it's one of those drivers that don't actually bind to
+		 * their device using driver core, then don't wait on this
+		 * supplier device indefinitely.
+		 */
+		if (sup_dev->links.status == DL_DEV_NO_DRIVER &&
+		    sup_handle->flags & FWNODE_FLAG_INITIALIZED) {
+			ret = -EINVAL;
+			goto out;
+		}
+
 		/*
 		 * If this fails, it is due to cycles in device links.  Just
 		 * give up on this link and treat it as invalid.
@@ -1655,6 +1666,10 @@ static int fw_devlink_create_devlink(struct device *con,
 		goto out;
 	}
 
+	/* Supplier that's already initialized without a struct device. */
+	if (sup_handle->flags & FWNODE_FLAG_INITIALIZED)
+		return -EINVAL;
+
 	/*
 	 * DL_FLAG_SYNC_STATE_ONLY doesn't block probing and supports
 	 * cycles. So cycle detection isn't necessary and shouldn't be

include/linux/fwnode.h

@@ -11,18 +11,21 @@
 
 #include <linux/types.h>
 #include <linux/list.h>
+#include <linux/err.h>
 
 struct fwnode_operations;
 struct device;
 
 /*
  * fwnode link flags
  *
- * LINKS_ADDED: The fwnode has already be parsed to add fwnode links.
- * NOT_DEVICE: The fwnode will never be populated as a struct device.
+ * LINKS_ADDED:	The fwnode has already be parsed to add fwnode links.
+ * NOT_DEVICE:	The fwnode will never be populated as a struct device.
+ * INITIALIZED: The hardware corresponding to fwnode has been initialized.
  */
 #define FWNODE_FLAG_LINKS_ADDED		BIT(0)
 #define FWNODE_FLAG_NOT_DEVICE		BIT(1)
+#define FWNODE_FLAG_INITIALIZED		BIT(2)
 
 struct fwnode_handle {
 	struct fwnode_handle *secondary;
@@ -161,6 +164,18 @@ static inline void fwnode_init(struct fwnode_handle *fwnode,
 	INIT_LIST_HEAD(&fwnode->suppliers);
 }
 
+static inline void fwnode_dev_initialized(struct fwnode_handle *fwnode,
+					  bool initialized)
+{
+	if (IS_ERR_OR_NULL(fwnode))
+		return;
+
+	if (initialized)
+		fwnode->flags |= FWNODE_FLAG_INITIALIZED;
+	else
+		fwnode->flags &= ~FWNODE_FLAG_INITIALIZED;
+}
+
 extern u32 fw_devlink_get_flags(void);
 extern bool fw_devlink_is_strict(void);
 int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup);