linux-kernel - [RFC PATCH 1/6] of: reserved-memory: Add reserved_mem_device

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Message-Id: <88dbf7486b820bd713598f20efd51e327b9ff755.1753865268.git.viresh.kumar@linaro.org>
Date: Wed, 30 Jul 2025 14:59:30 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: linux-kernel@...r.kernel.org,
	Rob Herring <robh@...nel.org>,
	Saravana Kannan <saravanak@...gle.com>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
	Arnd Bergmann <arnd@...nel.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Alex Bennée <alex.bennee@...aro.org>,
	Bill Mills <bill.mills@...aro.org>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	devicetree@...r.kernel.org,
	virtualization@...ts.linux.dev,
	Sudeep Holla <sudeep.holla@....com>,
	Bertrand Marquis <bertrand.marquis@....com>,
	"Edgar E . Iglesias" <edgar.iglesias@....com>,
	Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>
Subject: [RFC PATCH  1/6] of: reserved-memory: Add reserved_mem_device_init()

This adds reserved_mem_device_init() helper to attach the specified
reserved-memory region to the device.

This is required to attach a reserved-memory region with a non-DT
device.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/of/of_reserved_mem.c    | 64 ++++++++++++++++++++-------------
 include/linux/of_reserved_mem.h |  7 ++++
 2 files changed, 47 insertions(+), 24 deletions(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 77016c0cc296..e0a86c3fa656 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -606,6 +606,45 @@ struct rmem_assigned_device {
 static LIST_HEAD(of_rmem_assigned_device_list);
 static DEFINE_MUTEX(of_rmem_assigned_device_mutex);
 
+/**
+ * reserved_mem_device_init() - assign reserved memory region to given device
+ * @dev:	Pointer to the device to configure
+ * @rmem:	Pointer to the reserved memory region
+ *
+ * This function assigns the @rmem reserved memory region to the @dev device.
+ *
+ * Returns error code or zero on success.
+ */
+int reserved_mem_device_init(struct device *dev, struct reserved_mem *rmem)
+{
+	struct rmem_assigned_device *rd;
+	int ret;
+
+	if (!dev || !rmem || !rmem->ops || !rmem->ops->device_init)
+		return -EINVAL;
+
+	rd = kmalloc(sizeof(*rd), GFP_KERNEL);
+	if (!rd)
+		return -ENOMEM;
+
+	ret = rmem->ops->device_init(rmem, dev);
+	if (ret == 0) {
+		rd->dev = dev;
+		rd->rmem = rmem;
+
+		mutex_lock(&of_rmem_assigned_device_mutex);
+		list_add(&rd->list, &of_rmem_assigned_device_list);
+		mutex_unlock(&of_rmem_assigned_device_mutex);
+
+		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
+	} else {
+		kfree(rd);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(reserved_mem_device_init);
+
 /**
  * of_reserved_mem_device_init_by_idx() - assign reserved memory region to
  *					  given device
@@ -624,10 +663,8 @@ static DEFINE_MUTEX(of_rmem_assigned_device_mutex);
 int of_reserved_mem_device_init_by_idx(struct device *dev,
 				       struct device_node *np, int idx)
 {
-	struct rmem_assigned_device *rd;
 	struct device_node *target;
 	struct reserved_mem *rmem;
-	int ret;
 
 	if (!np || !dev)
 		return -EINVAL;
@@ -644,28 +681,7 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
 	rmem = of_reserved_mem_lookup(target);
 	of_node_put(target);
 
-	if (!rmem || !rmem->ops || !rmem->ops->device_init)
-		return -EINVAL;
-
-	rd = kmalloc(sizeof(struct rmem_assigned_device), GFP_KERNEL);
-	if (!rd)
-		return -ENOMEM;
-
-	ret = rmem->ops->device_init(rmem, dev);
-	if (ret == 0) {
-		rd->dev = dev;
-		rd->rmem = rmem;
-
-		mutex_lock(&of_rmem_assigned_device_mutex);
-		list_add(&rd->list, &of_rmem_assigned_device_list);
-		mutex_unlock(&of_rmem_assigned_device_mutex);
-
-		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
-	} else {
-		kfree(rd);
-	}
-
-	return ret;
+	return reserved_mem_device_init(dev, rmem);
 }
 EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_idx);
 
diff --git a/include/linux/of_reserved_mem.h b/include/linux/of_reserved_mem.h
index f573423359f4..3933f1d39e9a 100644
--- a/include/linux/of_reserved_mem.h
+++ b/include/linux/of_reserved_mem.h
@@ -37,6 +37,7 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
 int of_reserved_mem_device_init_by_name(struct device *dev,
 					struct device_node *np,
 					const char *name);
+int reserved_mem_device_init(struct device *dev, struct reserved_mem *rmem);
 void of_reserved_mem_device_release(struct device *dev);
 
 struct reserved_mem *of_reserved_mem_lookup(struct device_node *np);
@@ -64,6 +65,12 @@ static inline int of_reserved_mem_device_init_by_name(struct device *dev,
 	return -ENOSYS;
 }
 
+static inline int reserved_mem_device_init(struct device *dev,
+					   struct reserved_mem *rmem)
+{
+	return -ENOSYS;
+}
+
 static inline void of_reserved_mem_device_release(struct device *pdev) { }
 
 static inline struct reserved_mem *of_reserved_mem_lookup(struct device_node *np)
-- 
2.31.1.272.g89b43f80a514