linux-kernel - [PATCH v2 2/4] of: Simplify of_dma_set_restricted_buffer() to use of_for_each

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Message-Id: <20250423-dt-memory-region-v2-v2-2-2fbd6ebd3c88@kernel.org>
Date: Wed, 23 Apr 2025 14:42:14 -0500
From: "Rob Herring (Arm)" <robh@...nel.org>
To: Saravana Kannan <saravanak@...gle.com>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 Bjorn Andersson <andersson@...nel.org>, 
 Mathieu Poirier <mathieu.poirier@...aro.org>, 
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, 
 Patrice Chotard <patrice.chotard@...s.st.com>, 
 Maxime Coquelin <mcoquelin.stm32@...il.com>, 
 Alexandre Torgue <alexandre.torgue@...s.st.com>, 
 Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>, 
 Chen-Yu Tsai <wens@...nel.org>
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-remoteproc@...r.kernel.org, imx@...ts.linux.dev, 
 linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org, 
 linux-stm32@...md-mailman.stormreply.com
Subject: [PATCH v2 2/4] of: Simplify of_dma_set_restricted_buffer() to use
 of_for_each_phandle()

Simplify of_dma_set_restricted_buffer() by using of_property_present()
and of_for_each_phandle() iterator.

Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
---
v2:
 - Maintain prior behavior only warning if
   of_reserved_mem_device_init_by_idx() fails
---
 drivers/of/device.c | 31 +++++++++++--------------------
 1 file changed, 11 insertions(+), 20 deletions(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 5053e5d532cc..c80426510ec2 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -35,44 +35,35 @@ EXPORT_SYMBOL(of_match_device);
 static void
 of_dma_set_restricted_buffer(struct device *dev, struct device_node *np)
 {
-	struct device_node *node, *of_node = dev->of_node;
-	int count, i;
+	struct device_node *of_node = dev->of_node;
+	struct of_phandle_iterator it;
+	int rc, i = 0;
 
 	if (!IS_ENABLED(CONFIG_DMA_RESTRICTED_POOL))
 		return;
 
-	count = of_property_count_elems_of_size(of_node, "memory-region",
-						sizeof(u32));
 	/*
 	 * If dev->of_node doesn't exist or doesn't contain memory-region, try
 	 * the OF node having DMA configuration.
 	 */
-	if (count <= 0) {
+	if (!of_property_present(of_node, "memory-region"))
 		of_node = np;
-		count = of_property_count_elems_of_size(
-			of_node, "memory-region", sizeof(u32));
-	}
 
-	for (i = 0; i < count; i++) {
-		node = of_parse_phandle(of_node, "memory-region", i);
+	of_for_each_phandle(&it, rc, of_node, "memory-region", NULL, 0) {
 		/*
 		 * There might be multiple memory regions, but only one
 		 * restricted-dma-pool region is allowed.
 		 */
-		if (of_device_is_compatible(node, "restricted-dma-pool") &&
-		    of_device_is_available(node)) {
-			of_node_put(node);
+		if (of_device_is_compatible(it.node, "restricted-dma-pool") &&
+		    of_device_is_available(it.node)) {
+			if (of_reserved_mem_device_init_by_idx(dev, of_node, i))
+				dev_warn(dev, "failed to initialise \"restricted-dma-pool\" memory node\n");
+			of_node_put(it.node);
 			break;
 		}
-		of_node_put(node);
+		i++;
 	}
 
-	/*
-	 * Attempt to initialize a restricted-dma-pool region if one was found.
-	 * Note that count can hold a negative error code.
-	 */
-	if (i < count && of_reserved_mem_device_init_by_idx(dev, of_node, i))
-		dev_warn(dev, "failed to initialise \"restricted-dma-pool\" memory node\n");
 }
 
 /**

-- 
2.47.2