driver core: Add fw_devlink.strict kernel param

This param allows forcing all dependencies to be treated as mandatory.
This will be useful for boards in which all optional dependencies like
IOMMUs and DMAs need to be treated as mandatory dependencies.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210205222644.2357303-4-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/admin-guide/kernel-parameters.txt

@@ -1433,6 +1433,11 @@
 				to enforce probe and suspend/resume ordering.
 			rpm --	Like "on", but also use to order runtime PM.
 
+	fw_devlink.strict=<bool>
+			[KNL] Treat all inferred dependencies as mandatory
+			dependencies. This only applies for fw_devlink=on|rpm.
+			Format: <bool>
+
 	gamecon.map[2|3]=
 			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
 			support via parallel port (up to 5 devices per port)

drivers/base/core.c

@@ -1521,6 +1521,13 @@ static int __init fw_devlink_setup(char *arg)
 }
 early_param("fw_devlink", fw_devlink_setup);
 
+static bool fw_devlink_strict;
+static int __init fw_devlink_strict_setup(char *arg)
+{
+	return strtobool(arg, &fw_devlink_strict);
+}
+early_param("fw_devlink.strict", fw_devlink_strict_setup);
+
 u32 fw_devlink_get_flags(void)
 {
 	return fw_devlink_flags;
@@ -1531,6 +1538,11 @@ static bool fw_devlink_is_permissive(void)
 	return fw_devlink_flags == FW_DEVLINK_FLAGS_PERMISSIVE;
 }
 
+bool fw_devlink_is_strict(void)
+{
+	return fw_devlink_strict && !fw_devlink_is_permissive();
+}
+
 static void fw_devlink_parse_fwnode(struct fwnode_handle *fwnode)
 {
 	if (fwnode->flags & FWNODE_FLAG_LINKS_ADDED)

include/linux/fwnode.h

@@ -162,6 +162,7 @@ static inline void fwnode_init(struct fwnode_handle *fwnode,
 }
 
 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);
 void fwnode_links_purge(struct fwnode_handle *fwnode);