linux-kernel - [PATCH v4 5/8] driver core: fw_devlink: Handle suppliers that don't use driver core

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Date:   Fri,  5 Feb 2021 14:26:41 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Jonathan Corbet <corbet@....net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Len Brown <len.brown@...el.com>, Len Brown <lenb@...nel.org>,
        Pavel Machek <pavel@....cz>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Saravana Kannan <saravanak@...gle.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-acpi@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        kernel-team@...roid.com
Subject: [PATCH v4 5/8] 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.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/base/core.c    | 15 +++++++++++++++
 include/linux/fwnode.h | 19 +++++++++++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index f466ab4f1c35..ea710b33bda6 100644
--- a/drivers/base/core.c
+++ b/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
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index d5caefe39d93..dfefd43a737c 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -11,6 +11,7 @@
 
 #include <linux/types.h>
 #include <linux/list.h>
+#include <linux/err.h>
 
 struct fwnode_operations;
 struct device;
@@ -18,11 +19,13 @@ 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);
-- 
2.30.0.478.g8a0d178c01-goog