linux-kernel - [PATCH v3 3/4] driver core: Add fw

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Message-Id: <20210204223921.1693487-4-saravanak@google.com>
Date:   Thu,  4 Feb 2021 14:39:20 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Len Brown <lenb@...nel.org>, Jonathan Corbet <corbet@....net>
Cc:     Saravana Kannan <saravanak@...gle.com>, kernel-team@...roid.com,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-acpi@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Marc Zyngier <maz@...nel.org>,
        Tudor Ambarus <Tudor.Ambarus@...rochip.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Martin Kaiser <martin@...ser.cx>
Subject: [PATCH v3 3/4] 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.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  5 +++++
 drivers/base/core.c                             | 12 ++++++++++++
 include/linux/fwnode.h                          |  1 +
 3 files changed, 18 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a10b545c2070..692b63644133 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/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)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index c95b1daabac7..f466ab4f1c35 100644
--- a/drivers/base/core.c
+++ b/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)
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 21082f11473f..d5caefe39d93 100644
--- a/include/linux/fwnode.h
+++ b/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);
 
-- 
2.30.0.365.g02bc693789-goog