[PATCH 2/4] net: ti: am65-cpsw-nuss: Enforce pinctrl state on the MDIO child node

[Maxime Ripard]

The binding represents the MDIO controller as a child device tree
node of the MAC device tree node.

The U-Boot driver mostly ignores that child device tree node and just
hardcodes the resources it uses to support both the MAC and MDIO in a
single driver.

However, some resources like pinctrl muxing states are thus ignored.
This has been a problem with device trees since Linux 6.5-rc1 which will
put some pinctrl states on the MDIO device tree node.

Let's rework the driver a bit to fetch the pinctrl state from the MDIO
node and apply it.

Signed-off-by: Maxime Ripard <mripard at kernel.org>
---
 drivers/net/ti/am65-cpsw-nuss.c | 49 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/net/ti/am65-cpsw-nuss.c b/drivers/net/ti/am65-cpsw-nuss.c
index f674b0baa359..2d579bf4af2c 100644
--- a/drivers/net/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ti/am65-cpsw-nuss.c
@@ -15,6 +15,7 @@
 #include <dm.h>
 #include <dm/device_compat.h>
 #include <dm/lists.h>
+#include <dm/pinctrl.h>
 #include <dma-uclass.h>
 #include <dm/of_access.h>
 #include <miiphy.h>
@@ -696,6 +697,50 @@ out:
 	return ret;
 }
 
+static ofnode am65_cpsw_find_mdio(ofnode parent)
+{
+	ofnode node;
+
+	ofnode_for_each_subnode(node, parent)
+		if (ofnode_device_is_compatible(node, "ti,cpsw-mdio"))
+			return node;
+
+	return ofnode_null();
+}
+
+static int am65_cpsw_setup_mdio(struct udevice *dev)
+{
+	ofnode mdio;
+	int ret;
+
+	mdio = am65_cpsw_find_mdio(dev_ofnode(dev));
+	if (!ofnode_valid(mdio))
+		return -ENODEV;
+
+	/*
+	 * The MDIO controller is represented in the DT binding by a
+	 * subnode of the MAC controller.
+	 *
+	 * Our driver largely ignores that and supports MDIO by
+	 * hardcoding the register offsets.
+	 *
+	 * However, some resources (clocks, pinctrl) might be tied to
+	 * the MDIO node, and thus ignored.
+	 *
+	 * Clocks are not a concern at the moment since it's shared
+	 * between the MAC and MDIO, so the driver handles both at the
+	 * same time.
+	 *
+	 * However, we do need to make sure the pins states tied to the
+	 * MDIO node are configured properly.
+	 */
+	ret = pinctrl_select_state_by_ofnode(dev, mdio, "default");
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static int am65_cpsw_probe_nuss(struct udevice *dev)
 {
 	struct am65_cpsw_common *cpsw_common = dev_get_priv(dev);
@@ -728,6 +773,10 @@ static int am65_cpsw_probe_nuss(struct udevice *dev)
 				AM65_CPSW_CPSW_NU_ALE_BASE;
 	cpsw_common->mdio_base = cpsw_common->ss_base + AM65_CPSW_MDIO_BASE;
 
+	ret = am65_cpsw_setup_mdio(dev);
+	if (ret)
+		goto out;
+
 	ports_np = dev_read_subnode(dev, "ethernet-ports");
 	if (!ofnode_valid(ports_np)) {
 		ret = -ENOENT;

-- 
2.41.0