diff mbox series

[v8,1/2] i2c: mux: Factor out channel node lookup

Message ID 6ff921823286515e75b62493e748ed08f4816358.1788181174.git.ahmadexp@gmail.com
State New
Headers show
Series i2c: mux: Propagate firmware nodes to channel adapters | expand

Commit Message

Ahmad Byagowi Aug. 31, 2026, 5:22 p.m. UTC 
Move the existing Device Tree channel-node lookup into a helper in
preparation for using generic firmware-node operations.

This is a pure refactoring with no functional change.

Signed-off-by: Ahmad Byagowi <ahmadexp@gmail.com>
---
 drivers/i2c/i2c-mux.c | 82 +++++++++++++++++++++++--------------------
 1 file changed, 44 insertions(+), 38 deletions(-)

Comments

Andy Shevchenko Sept. 1, 2026, 8:50 a.m. UTC | #1 
On Mon, Aug 31, 2026 at 10:22:06AM -0700, Ahmad Byagowi wrote:
> Move the existing Device Tree channel-node lookup into a helper in
> preparation for using generic firmware-node operations.
> 
> This is a pure refactoring with no functional change.

...

> +static struct device_node *
> +i2c_mux_get_channel_node(struct i2c_mux_core *muxc, u32 chan_id)
> +{
> +	struct device_node *dev_node = muxc->dev->of_node;

It's better for maintenance to split assignment (due to validation below).

	struct device_node *dev_node;

> +	struct device_node *mux_node, *child;
> +	u32 reg;
> +	int ret;

// also use getter
	dev_node = dev_of_node(dev);

> +	if (!dev_node)
> +		return NULL;

Looking at the code, it's NULL-aware as far as I can see and this check is just
a shortcut.

> +	if (muxc->arbitrator)
> +		mux_node = of_get_child_by_name(dev_node, "i2c-arb");
> +	else if (muxc->gate)
> +		mux_node = of_get_child_by_name(dev_node, "i2c-gate");
> +	else
> +		mux_node = of_get_child_by_name(dev_node, "i2c-mux");
> +
> +	if (mux_node) {
> +		/* A "reg" property indicates an old-style DT entry */
> +		if (!of_property_read_u32(mux_node, "reg", &reg)) {
> +			of_node_put(mux_node);
> +			mux_node = NULL;
> +		}
> +	}
> +
> +	if (!mux_node)
> +		mux_node = of_node_get(dev_node);
> +	else if (muxc->arbitrator || muxc->gate)
> +		return mux_node;
> +
> +	for_each_child_of_node(mux_node, child) {
> +		ret = of_property_read_u32(child, "reg", &reg);
> +		if (ret)
> +			continue;
> +		if (chan_id == reg)
> +			break;
> +	}
> +
> +	of_node_put(mux_node);
> +	return child;
> +}
diff mbox series

Patch

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 68a4c34b5987..77921e5132bc 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -264,6 +264,49 @@  static const struct i2c_lock_operations i2c_parent_lock_ops = {
 	.unlock_bus =  i2c_parent_unlock_bus,
 };
 
+static struct device_node *
+i2c_mux_get_channel_node(struct i2c_mux_core *muxc, u32 chan_id)
+{
+	struct device_node *dev_node = muxc->dev->of_node;
+	struct device_node *mux_node, *child;
+	u32 reg;
+	int ret;
+
+	if (!dev_node)
+		return NULL;
+
+	if (muxc->arbitrator)
+		mux_node = of_get_child_by_name(dev_node, "i2c-arb");
+	else if (muxc->gate)
+		mux_node = of_get_child_by_name(dev_node, "i2c-gate");
+	else
+		mux_node = of_get_child_by_name(dev_node, "i2c-mux");
+
+	if (mux_node) {
+		/* A "reg" property indicates an old-style DT entry */
+		if (!of_property_read_u32(mux_node, "reg", &reg)) {
+			of_node_put(mux_node);
+			mux_node = NULL;
+		}
+	}
+
+	if (!mux_node)
+		mux_node = of_node_get(dev_node);
+	else if (muxc->arbitrator || muxc->gate)
+		return mux_node;
+
+	for_each_child_of_node(mux_node, child) {
+		ret = of_property_read_u32(child, "reg", &reg);
+		if (ret)
+			continue;
+		if (chan_id == reg)
+			break;
+	}
+
+	of_node_put(mux_node);
+	return child;
+}
+
 int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
 			u32 force_nr, u32 chan_id)
 {
@@ -327,44 +370,7 @@  int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
 	 * Try to populate the mux adapter's of_node, expands to
 	 * nothing if !CONFIG_OF.
 	 */
-	if (muxc->dev->of_node) {
-		struct device_node *dev_node = muxc->dev->of_node;
-		struct device_node *mux_node, *child = NULL;
-		u32 reg;
-
-		if (muxc->arbitrator)
-			mux_node = of_get_child_by_name(dev_node, "i2c-arb");
-		else if (muxc->gate)
-			mux_node = of_get_child_by_name(dev_node, "i2c-gate");
-		else
-			mux_node = of_get_child_by_name(dev_node, "i2c-mux");
-
-		if (mux_node) {
-			/* A "reg" property indicates an old-style DT entry */
-			if (!of_property_read_u32(mux_node, "reg", &reg)) {
-				of_node_put(mux_node);
-				mux_node = NULL;
-			}
-		}
-
-		if (!mux_node)
-			mux_node = of_node_get(dev_node);
-		else if (muxc->arbitrator || muxc->gate)
-			child = of_node_get(mux_node);
-
-		if (!child) {
-			for_each_child_of_node(mux_node, child) {
-				ret = of_property_read_u32(child, "reg", &reg);
-				if (ret)
-					continue;
-				if (chan_id == reg)
-					break;
-			}
-		}
-
-		priv->adap.dev.of_node = child;
-		of_node_put(mux_node);
-	}
+	priv->adap.dev.of_node = i2c_mux_get_channel_node(muxc, chan_id);
 
 	/*
 	 * Associate the mux channel with an ACPI node.