[PATCH v2 1/3] 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 some device trees that will put some
pinctrl states on the MDIO device tree node, like the SK-AM62 Device
Tree does.

Let's rework the driver a bit to create a dummy MDIO driver that we will
then get during our initialization to force the core to select the right
muxing.

Signed-off-by: Maxime Ripard <mripard at kernel.org>
---
 drivers/net/ti/Kconfig          |  1 +
 drivers/net/ti/am65-cpsw-nuss.c | 67 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/drivers/net/ti/Kconfig b/drivers/net/ti/Kconfig
index e13dbc940182..08c81f79adf9 100644
--- a/drivers/net/ti/Kconfig
+++ b/drivers/net/ti/Kconfig
@@ -41,6 +41,7 @@ endchoice
 config TI_AM65_CPSW_NUSS
 	bool "TI K3 AM65x MCU CPSW Nuss Ethernet controller driver"
 	depends on ARCH_K3
+	imply DM_MDIO
 	imply MISC_INIT_R
 	imply MISC
 	select PHYLIB
diff --git a/drivers/net/ti/am65-cpsw-nuss.c b/drivers/net/ti/am65-cpsw-nuss.c
index 3069550d53c2..ac7907e7ef70 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>
@@ -580,14 +581,69 @@ static const struct soc_attr k3_mdio_soc_data[] = {
 	{ /* sentinel */ },
 };
 
+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_mdio_setup(struct udevice *dev)
+{
+	struct am65_cpsw_priv *priv = dev_get_priv(dev);
+	struct am65_cpsw_common	*cpsw_common = priv->cpsw_common;
+	struct udevice *mdio_dev;
+	ofnode mdio;
+	int ret;
+
+	mdio = am65_cpsw_find_mdio(dev_ofnode(cpsw_common->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. Fortunately, the core DM
+	 * does that for use when we get a device, so we can work around
+	 * that whole issue by just requesting a dummy MDIO driver to
+	 * probe, and our pins will get muxed.
+	 */
+	ret = uclass_get_device_by_ofnode(UCLASS_MDIO, mdio, &mdio_dev);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static int am65_cpsw_mdio_init(struct udevice *dev)
 {
 	struct am65_cpsw_priv *priv = dev_get_priv(dev);
 	struct am65_cpsw_common	*cpsw_common = priv->cpsw_common;
+	int ret;
 
 	if (!priv->has_phy || cpsw_common->bus)
 		return 0;
 
+	ret = am65_cpsw_mdio_setup(dev);
+	if (ret)
+		return ret;
+
 	cpsw_common->bus = cpsw_mdio_init(dev->name,
 					  cpsw_common->mdio_base,
 					  cpsw_common->bus_freq,
@@ -854,3 +910,14 @@ U_BOOT_DRIVER(am65_cpsw_nuss_port) = {
 	.plat_auto	= sizeof(struct eth_pdata),
 	.flags = DM_FLAG_ALLOC_PRIV_DMA | DM_FLAG_OS_PREPARE,
 };
+
+static const struct udevice_id am65_cpsw_mdio_ids[] = {
+	{ .compatible = "ti,cpsw-mdio" },
+	{ }
+};
+
+U_BOOT_DRIVER(am65_cpsw_mdio) = {
+	.name		= "am65_cpsw_mdio",
+	.id		= UCLASS_MDIO,
+	.of_match	= am65_cpsw_mdio_ids,
+};

-- 
2.41.0