[PATCH v2 net-next 06/15] net: dsa: sja1105: transition OF-based MDIO controllers to standalone sub-devices

@@ -5,6 +5,7 @@ sja1105-objs := \
     sja1105_spi.o \
     sja1105_main.o \
     sja1105_mdio.o \
+    sja1105_subdev.o \
     sja1105_flower.o \
     sja1105_ethtool.o \
     sja1105_devlink.o \

@@ -91,8 +91,6 @@ struct sja1105_regs {
 	u64 rmii_ref_clk[SJA1105_MAX_NUM_PORTS];
 	u64 rmii_ext_tx_clk[SJA1105_MAX_NUM_PORTS];
 	u64 stats[__MAX_SJA1105_STATS_AREA][SJA1105_MAX_NUM_PORTS];
-	u64 mdio_100base_tx;
-	u64 mdio_100base_t1;
 	u64 pcs_base[SJA1105_MAX_NUM_PORTS];
 };
 

@@ -278,8 +276,6 @@ struct sja1105_private {
 	struct mutex dynamic_config_lock;
 	struct devlink_region **regions;
 	struct sja1105_cbs_entry *cbs;
-	struct mii_bus *mdio_base_t1;
-	struct mii_bus *mdio_base_tx;
 	struct mii_bus *mdio_pcs;
 	struct phylink_pcs *pcs[SJA1105_MAX_NUM_PORTS];
 	struct sja1105_ptp_data ptp_data;

@@ -23,6 +23,7 @@
 #include <linux/units.h>
 
 #include "sja1105.h"
+#include "sja1105_subdev.h"
 #include "sja1105_tas.h"
 
 #define SJA1105_UNKNOWN_MULTICAST	0x010000000000ull

@@ -3329,6 +3330,13 @@ static int sja1105_probe(struct spi_device *spi)
 		return rc;
 	}
 
+	rc = devm_sja1105_add_subdevs(ds);
+	if (rc) {
+		dev_err(ds->dev, "Failed to create child devices: %pe\n",
+			ERR_PTR(rc));
+		return rc;
+	}
+
 	if (IS_ENABLED(CONFIG_NET_SCH_CBS)) {
 		priv->cbs = devm_kcalloc(dev, priv->info->num_cbs_shapers,
 					 sizeof(struct sja1105_cbs_entry),

@@ -133,238 +133,6 @@ int sja1110_pcs_mdio_write_c45(struct mii_bus *bus, int phy, int mmd, int reg,
 				&tmp, NULL);
 }
 
-enum sja1105_mdio_opcode {
-	SJA1105_C45_ADDR = 0,
-	SJA1105_C22 = 1,
-	SJA1105_C45_DATA = 2,
-	SJA1105_C45_DATA_AUTOINC = 3,
-};
-
-static u64 sja1105_base_t1_encode_addr(struct sja1105_private *priv,
-				       int phy, enum sja1105_mdio_opcode op,
-				       int xad)
-{
-	const struct sja1105_regs *regs = priv->info->regs;
-
-	return regs->mdio_100base_t1 | (phy << 7) | (op << 5) | (xad << 0);
-}
-
-static int sja1105_base_t1_mdio_read_c22(struct mii_bus *bus, int phy, int reg)
-{
-	struct sja1105_mdio_private *mdio_priv = bus->priv;
-	struct sja1105_private *priv = mdio_priv->priv;
-	u64 addr;
-	u32 tmp;
-	int rc;
-
-	addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C22, reg & 0x1f);
-
-	rc = sja1105_xfer_u32(priv, SPI_READ, addr, &tmp, NULL);
-	if (rc < 0)
-		return rc;
-
-	return tmp & 0xffff;
-}
-
-static int sja1105_base_t1_mdio_read_c45(struct mii_bus *bus, int phy,
-					 int mmd, int reg)
-{
-	struct sja1105_mdio_private *mdio_priv = bus->priv;
-	struct sja1105_private *priv = mdio_priv->priv;
-	u64 addr;
-	u32 tmp;
-	int rc;
-
-	addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C45_ADDR, mmd);
-
-	rc = sja1105_xfer_u32(priv, SPI_WRITE, addr, &reg, NULL);
-	if (rc < 0)
-		return rc;
-
-	addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C45_DATA, mmd);
-
-	rc = sja1105_xfer_u32(priv, SPI_READ, addr, &tmp, NULL);
-	if (rc < 0)
-		return rc;
-
-	return tmp & 0xffff;
-}
-
-static int sja1105_base_t1_mdio_write_c22(struct mii_bus *bus, int phy, int reg,
-					  u16 val)
-{
-	struct sja1105_mdio_private *mdio_priv = bus->priv;
-	struct sja1105_private *priv = mdio_priv->priv;
-	u64 addr;
-	u32 tmp;
-
-	addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C22, reg & 0x1f);
-
-	tmp = val & 0xffff;
-
-	return sja1105_xfer_u32(priv, SPI_WRITE, addr, &tmp, NULL);
-}
-
-static int sja1105_base_t1_mdio_write_c45(struct mii_bus *bus, int phy,
-					  int mmd, int reg, u16 val)
-{
-	struct sja1105_mdio_private *mdio_priv = bus->priv;
-	struct sja1105_private *priv = mdio_priv->priv;
-	u64 addr;
-	u32 tmp;
-	int rc;
-
-	addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C45_ADDR, mmd);
-
-	rc = sja1105_xfer_u32(priv, SPI_WRITE, addr, &reg, NULL);
-	if (rc < 0)
-		return rc;
-
-	addr = sja1105_base_t1_encode_addr(priv, phy, SJA1105_C45_DATA, mmd);
-
-	tmp = val & 0xffff;
-
-	return sja1105_xfer_u32(priv, SPI_WRITE, addr, &tmp, NULL);
-}
-
-static int sja1105_base_tx_mdio_read(struct mii_bus *bus, int phy, int reg)
-{
-	struct sja1105_mdio_private *mdio_priv = bus->priv;
-	struct sja1105_private *priv = mdio_priv->priv;
-	const struct sja1105_regs *regs = priv->info->regs;
-	u32 tmp;
-	int rc;
-
-	rc = sja1105_xfer_u32(priv, SPI_READ, regs->mdio_100base_tx + reg,
-			      &tmp, NULL);
-	if (rc < 0)
-		return rc;
-
-	return tmp & 0xffff;
-}
-
-static int sja1105_base_tx_mdio_write(struct mii_bus *bus, int phy, int reg,
-				      u16 val)
-{
-	struct sja1105_mdio_private *mdio_priv = bus->priv;
-	struct sja1105_private *priv = mdio_priv->priv;
-	const struct sja1105_regs *regs = priv->info->regs;
-	u32 tmp = val;
-
-	return sja1105_xfer_u32(priv, SPI_WRITE, regs->mdio_100base_tx + reg,
-				&tmp, NULL);
-}
-
-static int sja1105_mdiobus_base_tx_register(struct sja1105_private *priv,
-					    struct device_node *mdio_node)
-{
-	struct sja1105_mdio_private *mdio_priv;
-	struct device_node *np;
-	struct mii_bus *bus;
-	int rc = 0;
-
-	np = of_get_compatible_child(mdio_node, "nxp,sja1110-base-tx-mdio");
-	if (!np)
-		return 0;
-
-	if (!of_device_is_available(np))
-		goto out_put_np;
-
-	bus = mdiobus_alloc_size(sizeof(*mdio_priv));
-	if (!bus) {
-		rc = -ENOMEM;
-		goto out_put_np;
-	}
-
-	bus->name = "SJA1110 100base-TX MDIO bus";
-	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-base-tx",
-		 dev_name(priv->ds->dev));
-	bus->read = sja1105_base_tx_mdio_read;
-	bus->write = sja1105_base_tx_mdio_write;
-	bus->parent = priv->ds->dev;
-	mdio_priv = bus->priv;
-	mdio_priv->priv = priv;
-
-	rc = of_mdiobus_register(bus, np);
-	if (rc) {
-		mdiobus_free(bus);
-		goto out_put_np;
-	}
-
-	priv->mdio_base_tx = bus;
-
-out_put_np:
-	of_node_put(np);
-
-	return rc;
-}
-
-static void sja1105_mdiobus_base_tx_unregister(struct sja1105_private *priv)
-{
-	if (!priv->mdio_base_tx)
-		return;
-
-	mdiobus_unregister(priv->mdio_base_tx);
-	mdiobus_free(priv->mdio_base_tx);
-	priv->mdio_base_tx = NULL;
-}
-
-static int sja1105_mdiobus_base_t1_register(struct sja1105_private *priv,
-					    struct device_node *mdio_node)
-{
-	struct sja1105_mdio_private *mdio_priv;
-	struct device_node *np;
-	struct mii_bus *bus;
-	int rc = 0;
-
-	np = of_get_compatible_child(mdio_node, "nxp,sja1110-base-t1-mdio");
-	if (!np)
-		return 0;
-
-	if (!of_device_is_available(np))
-		goto out_put_np;
-
-	bus = mdiobus_alloc_size(sizeof(*mdio_priv));
-	if (!bus) {
-		rc = -ENOMEM;
-		goto out_put_np;
-	}
-
-	bus->name = "SJA1110 100base-T1 MDIO bus";
-	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-base-t1",
-		 dev_name(priv->ds->dev));
-	bus->read = sja1105_base_t1_mdio_read_c22;
-	bus->write = sja1105_base_t1_mdio_write_c22;
-	bus->read_c45 = sja1105_base_t1_mdio_read_c45;
-	bus->write_c45 = sja1105_base_t1_mdio_write_c45;
-	bus->parent = priv->ds->dev;
-	mdio_priv = bus->priv;
-	mdio_priv->priv = priv;
-
-	rc = of_mdiobus_register(bus, np);
-	if (rc) {
-		mdiobus_free(bus);
-		goto out_put_np;
-	}
-
-	priv->mdio_base_t1 = bus;
-
-out_put_np:
-	of_node_put(np);
-
-	return rc;
-}
-
-static void sja1105_mdiobus_base_t1_unregister(struct sja1105_private *priv)
-{
-	if (!priv->mdio_base_t1)
-		return;
-
-	mdiobus_unregister(priv->mdio_base_t1);
-	mdiobus_free(priv->mdio_base_t1);
-	priv->mdio_base_t1 = NULL;
-}
-
 static int sja1105_mdiobus_pcs_register(struct sja1105_private *priv)
 {
 	struct sja1105_mdio_private *mdio_priv;

@@ -459,49 +227,13 @@ static void sja1105_mdiobus_pcs_unregister(struct sja1105_private *priv)
 int sja1105_mdiobus_register(struct dsa_switch *ds)
 {
 	struct sja1105_private *priv = ds->priv;
-	const struct sja1105_regs *regs = priv->info->regs;
-	struct device_node *switch_node = ds->dev->of_node;
-	struct device_node *mdio_node;
-	int rc;
-
-	rc = sja1105_mdiobus_pcs_register(priv);
-	if (rc)
-		return rc;
-
-	mdio_node = of_get_available_child_by_name(switch_node, "mdios");
-	if (!mdio_node)
-		return 0;
 
-	if (regs->mdio_100base_tx != SJA1105_RSV_ADDR) {
-		rc = sja1105_mdiobus_base_tx_register(priv, mdio_node);
-		if (rc)
-			goto err_put_mdio_node;
-	}
-
-	if (regs->mdio_100base_t1 != SJA1105_RSV_ADDR) {
-		rc = sja1105_mdiobus_base_t1_register(priv, mdio_node);
-		if (rc)
-			goto err_free_base_tx_mdiobus;
-	}
-
-	of_node_put(mdio_node);
-
-	return 0;
-
-err_free_base_tx_mdiobus:
-	sja1105_mdiobus_base_tx_unregister(priv);
-err_put_mdio_node:
-	of_node_put(mdio_node);
-	sja1105_mdiobus_pcs_unregister(priv);
-
-	return rc;
+	return sja1105_mdiobus_pcs_register(priv);
 }
 
 void sja1105_mdiobus_unregister(struct dsa_switch *ds)
 {
 	struct sja1105_private *priv = ds->priv;
 
-	sja1105_mdiobus_base_t1_unregister(priv);
-	sja1105_mdiobus_base_tx_unregister(priv);
 	sja1105_mdiobus_pcs_unregister(priv);
 }

@@ -495,8 +495,6 @@ static const struct sja1105_regs sja1105et_regs = {
 	.ptpclkval = 0x18, /* Spans 0x18 to 0x19 */
 	.ptpclkrate = 0x1A,
 	.ptpclkcorp = 0x1D,
-	.mdio_100base_tx = SJA1105_RSV_ADDR,
-	.mdio_100base_t1 = SJA1105_RSV_ADDR,
 };
 
 static const struct sja1105_regs sja1105pqrs_regs = {

@@ -534,8 +532,6 @@ static const struct sja1105_regs sja1105pqrs_regs = {
 	.ptpclkrate = 0x1B,
 	.ptpclkcorp = 0x1E,
 	.ptpsyncts = 0x1F,
-	.mdio_100base_tx = SJA1105_RSV_ADDR,
-	.mdio_100base_t1 = SJA1105_RSV_ADDR,
 };
 
 static const struct sja1105_regs sja1110_regs = {

@@ -618,8 +614,6 @@ static const struct sja1105_regs sja1110_regs = {
 	.ptpclkrate = SJA1110_SPI_ADDR(0x74),
 	.ptpclkcorp = SJA1110_SPI_ADDR(0x80),
 	.ptpsyncts = SJA1110_SPI_ADDR(0x84),
-	.mdio_100base_tx = 0x1c2400,
-	.mdio_100base_t1 = 0x1c1000,
 	.pcs_base = {SJA1105_RSV_ADDR, 0x1c1400, 0x1c1800, 0x1c1c00, 0x1c2000,
 		     SJA1105_RSV_ADDR, SJA1105_RSV_ADDR, SJA1105_RSV_ADDR,
 		     SJA1105_RSV_ADDR, SJA1105_RSV_ADDR, SJA1105_RSV_ADDR},

@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2025 NXP
+ */
+#include <linux/device/devres.h>
+#include <linux/ioport.h>
+#include <linux/platform_device.h>
+
+#include "sja1105.h"
+#include "sja1105_subdev.h"
+
+static const struct resource sja1110_mdio_cbt1_res =
+	DEFINE_RES_REG_NAMED(0x704000, 0x4000, "mdio_cbt1");
+
+static const struct resource sja1110_mdio_cbtx_res =
+	DEFINE_RES_REG_NAMED(0x709000, 0x1000, "mdio_cbtx");
+
+static bool fwnode_is_hierarchical_child(struct fwnode_handle *child,
+					 struct fwnode_handle *parent)
+{
+	struct fwnode_handle *next = child;
+
+	do {
+		if (next == parent)
+			return true;
+		next = fwnode_get_parent(next);
+	} while (next);
+
+	return false;
+}
+
+static void of_subdev_del(void *data)
+{
+	struct platform_device *pdev = data;
+
+	platform_device_unregister(pdev);
+}
+
+/**
+ * devm_of_subdev_add() - Register an OF sub-device as a managed platform device
+ * @pdevinfo: Platform device information structure containing parent, fwnode,
+ *	name, resources, etc.
+ *
+ * This function registers a platform device as a sub-device of
+ * @pdevinfo.parent using the information provided in @pdevinfo. The sub-device
+ * will be automatically unregistered when @pdevinfo.parent is removed, thanks
+ * to devres management.
+ *
+ * If the fwnode specified in @pdevinfo is not available (disabled in device
+ * tree), this function returns success without creating the device.
+ *
+ * For the sub-device drivers to access their registers, a form of
+ * devm_regmap_init(parent) should have been called prior to this, which
+ * makes the parent regmap visible via dev_get_regmap(&pdev->dev.parent)
+ * in the sub-device driver. The entire address space is made available through
+ * this regmap to all sub-devices, although they are expected to segment it
+ * according to the given resources.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int devm_of_subdev_add(const struct platform_device_info *pdevinfo)
+{
+	struct device *parent = pdevinfo->parent;
+	struct platform_device *pdev;
+
+	if (!fwnode_device_is_available(pdevinfo->fwnode))
+		return 0;
+
+	/* To avoid API abuse, ensure that the sub-device fwnode is,
+	 * in fact, related to the parent.
+	 */
+	if (!fwnode_is_hierarchical_child(pdevinfo->fwnode, dev_fwnode(parent)))
+		return -EINVAL;
+
+	pdev = platform_device_register_full(pdevinfo);
+	if (IS_ERR(pdev))
+		return PTR_ERR(pdev);
+
+	return devm_add_action_or_reset(parent, of_subdev_del, pdev);
+}
+
+static int devm_sja1105_add_mdio_subdev(struct device *parent,
+					struct device_node *np,
+					const struct resource *res,
+					size_t num_res)
+{
+	struct platform_device_info subdev;
+	char name[64];
+	u32 reg;
+	int err;
+
+	err = of_property_read_u32(np, "reg", &reg);
+	if (err)
+		return err;
+
+	snprintf(name, sizeof(name), "%s.%pOFn", dev_name(parent), np);
+	subdev = (struct platform_device_info) {
+		.parent = parent,
+		.fwnode = of_fwnode_handle(np),
+		.name = name,
+		.id = reg,
+		.res = res,
+		.num_res = num_res,
+	};
+
+	return devm_of_subdev_add(&subdev);
+}
+
+/* Legacy nodes which lack a proper resource description in the device tree,
+ * so we need to specify it manually.
+ */
+static int devm_sja1105_add_mdio_subdevs(struct dsa_switch *ds,
+					 struct device_node *mdio_node)
+{
+	struct device *parent = ds->dev;
+	struct device_node *np;
+	int err;
+
+	np = of_get_compatible_child(mdio_node, "nxp,sja1110-base-tx-mdio");
+	if (np) {
+		err = devm_sja1105_add_mdio_subdev(parent, np,
+						   &sja1110_mdio_cbtx_res, 1);
+		of_node_put(np);
+		if (err)
+			return err;
+	}
+
+	np = of_get_compatible_child(mdio_node, "nxp,sja1110-base-t1-mdio");
+	if (np) {
+		err = devm_sja1105_add_mdio_subdev(parent, np,
+						   &sja1110_mdio_cbt1_res, 1);
+		of_node_put(np);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+int devm_sja1105_add_subdevs(struct dsa_switch *ds)
+{
+	struct device_node *switch_node = dev_of_node(ds->dev);
+	struct device_node *mdio_node;
+	int rc = 0;
+
+	mdio_node = of_get_available_child_by_name(switch_node, "mdios");
+	if (mdio_node) {
+		rc = devm_sja1105_add_mdio_subdevs(ds, mdio_node);
+		of_node_put(mdio_node);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright 2025-2026 NXP
+ */
+#ifndef _SJA1105_SUBDEV_H
+#define _SJA1105_SUBDEV_H
+
+int devm_sja1105_add_subdevs(struct dsa_switch *ds);
+
+#endif