[PATCH net-next 0/3] net: stmmac: add physical port identification support

[PATCH net-next 0/3] net: stmmac: add physical port identification support

[John Madieu]

This series adds physical port identification support to the stmmac driver,
enabling userspace to query hardware-stable identifiers for network interfaces
via ndo_get_phys_port_id() and ndo_get_phys_port_name().

On systems with multiple ethernet controllers sharing the same driver,
physical port identification provides stable identifiers that persist
across reboots and are independent of interface enumeration order.
This is particularly useful for predictable network interface naming
and for correlating interfaces with physical connectors.

The implementation follows a two-tier approach:

1. Generic stmmac support: Default implementations use the permanent MAC
   address as port ID and bus_id for port naming. This provides immediate
   benefit for all stmmac-based platforms.

2. Glue driver override: Platform drivers can provide custom callbacks
   for hardware-specific identification schemes. The Renesas GBETH driver
   implements this to support device tree-based port identification,
   addressing cases where hardware lacks unique identification registers.

The Renesas implementation constructs an 8-byte port identifier from:
- Permanent MAC address (if available) or Renesas OUI (74:90:50) as fallback
- Port index from device tree property or ethernet alias


John Madieu (3):
  net: stmmac: add physical port identification support
  dt-bindings: net: renesas-gbeth: Add port-id property
  net: stmmac: dwmac-renesas-gbeth: add physical port identification

 .../bindings/net/renesas,rzv2h-gbeth.yaml     | 19 +++++++
 .../stmicro/stmmac/dwmac-renesas-gbeth.c      | 56 +++++++++++++++++++
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 54 ++++++++++++++++++
 include/linux/stmmac.h                        |  5 ++
 4 files changed, 134 insertions(+)

-- 
2.25.1

[PATCH net-next 1/3] net: stmmac: add physical port identification support

[John Madieu]

Implement ndo_get_phys_port_id and ndo_get_phys_port_name callbacks
to provide physical port identification for all stmmac-based devices.

Default implementations use the permanent MAC address for port ID and
bus_id for port name. Glue drivers can override these by setting
get_phys_port_id and get_phys_port_name callbacks in plat_stmmacenet_data.

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 54 +++++++++++++++++++
 include/linux/stmmac.h                        |  5 ++
 2 files changed, 59 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 15b0c08ebd877..e8f642c9941b6 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -7151,6 +7151,58 @@ static void stmmac_get_stats64(struct net_device *dev, struct rtnl_link_stats64
 	stats->rx_missed_errors = priv->xstats.rx_missed_cntr;
 }
 
+/**
+ * stmmac_get_phys_port_id - Get physical port identification
+ * @dev: net device structure
+ * @ppid: pointer to physical port id structure
+ *
+ * Returns a unique physical port identifier. If the platform provides
+ * a custom callback, it is used. Otherwise, the permanent MAC address
+ * serves as the default identifier.
+ *
+ * Return: 0 on success, negative error code otherwise
+ */
+static int stmmac_get_phys_port_id(struct net_device *dev,
+				   struct netdev_phys_item_id *ppid)
+{
+	struct stmmac_priv *priv = netdev_priv(dev);
+
+	/* Allow glue driver to override */
+	if (priv->plat->get_phys_port_id)
+		return priv->plat->get_phys_port_id(dev, ppid);
+
+	/* Default: use permanent MAC address as port ID */
+	ppid->id_len = ETH_ALEN;
+	memcpy(ppid->id, dev->perm_addr, ETH_ALEN);
+
+	return 0;
+}
+
+/**
+ * stmmac_get_phys_port_name - Get physical port name
+ * @dev: net device structure
+ * @name: buffer to store the port name
+ * @len: length of the buffer
+ *
+ * Returns a human-readable physical port name. If the platform provides
+ * a custom callback, it is used. Otherwise, a default name based on
+ * the bus_id is generated.
+ *
+ * Return: 0 on success, negative error code otherwise
+ */
+static int stmmac_get_phys_port_name(struct net_device *dev,
+				     char *name, size_t len)
+{
+	struct stmmac_priv *priv = netdev_priv(dev);
+
+	/* Allow glue driver to override */
+	if (priv->plat->get_phys_port_name)
+		return priv->plat->get_phys_port_name(dev, name, len);
+
+	/* Default: use bus_id as port identifier */
+	return snprintf(name, len, "p%d", priv->plat->bus_id) >= len ? -EINVAL : 0;
+}
+
 static const struct net_device_ops stmmac_netdev_ops = {
 	.ndo_open = stmmac_open,
 	.ndo_start_xmit = stmmac_xmit,
@@ -7172,6 +7224,8 @@ static const struct net_device_ops stmmac_netdev_ops = {
 	.ndo_xsk_wakeup = stmmac_xsk_wakeup,
 	.ndo_hwtstamp_get = stmmac_hwtstamp_get,
 	.ndo_hwtstamp_set = stmmac_hwtstamp_set,
+	.ndo_get_phys_port_id = stmmac_get_phys_port_id,
+	.ndo_get_phys_port_name = stmmac_get_phys_port_name,
 };
 
 static void stmmac_reset_subtask(struct stmmac_priv *priv)
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 4f70a6551e68c..2b98c2d354804 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -277,6 +277,11 @@ struct plat_stmmacenet_data {
 	void (*pcs_exit)(struct stmmac_priv *priv);
 	struct phylink_pcs *(*select_pcs)(struct stmmac_priv *priv,
 					  phy_interface_t interface);
+	/* Physical port identification callbacks (optional, for glue driver override) */
+	int (*get_phys_port_id)(struct net_device *ndev,
+				struct netdev_phys_item_id *ppid);
+	int (*get_phys_port_name)(struct net_device *ndev,
+				  char *name, size_t len);
 	void *bsp_priv;
 	struct clk *stmmac_clk;
 	struct clk *pclk;
-- 
2.25.1

[PATCH net-next 2/3] dt-bindings: net: renesas-gbeth: Add port-id property

[John Madieu]

Add optional port-id property to identify ethernet ports on RZ/V2H
SoCs. The hardware doesn't provide unique identification registers
for multiple ethernet instances, so this property allows explicit
port identification from the device tree.

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
---
 .../bindings/net/renesas,rzv2h-gbeth.yaml     | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/renesas,rzv2h-gbeth.yaml b/Documentation/devicetree/bindings/net/renesas,rzv2h-gbeth.yaml
index bd53ab300f500..bb59c6a925d3f 100644
--- a/Documentation/devicetree/bindings/net/renesas,rzv2h-gbeth.yaml
+++ b/Documentation/devicetree/bindings/net/renesas,rzv2h-gbeth.yaml
@@ -117,6 +117,23 @@ properties:
           - description: AXI power-on system reset
           - description: AHB reset
 
+  renesas,port-id:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Optional unique port identifier for this ethernet interface.
+      Used for physical port identification (phys_port_id, phys_port_name).
+      If not specified, the ethernet alias index is used as fallback.
+    minimum: 0
+    maximum: 255
+
+  renesas,port-name:
+    $ref: /schemas/types.yaml#/definitions/string
+    description:
+      Optional custom name for the physical port. Used by
+      ndo_get_phys_port_name() for interface naming.
+      If not specified, "p<N>" format is used where N is the port-id
+      or ethernet alias index.
+
   pcs-handle:
     description:
       phandle pointing to a PCS sub-node compatible with
@@ -230,6 +247,8 @@ examples:
         snps,txpbl = <32>;
         snps,rxpbl = <32>;
         phy-handle = <&phy0>;
+        renesas,port-id = <0>;
+        renesas,port-name = "mgmt";
 
         stmmac_axi_setup: stmmac-axi-config {
             snps,lpi_en;
-- 
2.25.1

[PATCH net-next 3/3] net: stmmac: dwmac-renesas-gbeth: add physical port identification

[John Madieu]

Implement ndo_get_phys_port_id() and ndo_get_phys_port_name() callbacks
for the Renesas RZ/G3E GBETH driver.

The port ID is an 8-byte identifier constructed from:
- Permanent MAC address if available (addr_assign_type == NET_ADDR_PERM)
- Renesas OUI (74:90:50) as fallback for random/generated MACs
- Port index from 'port-id' DT property or ethernet alias

The port name resolution follows this hierarchy:
- 'port-name' DT property if specified (allows custom names like "mgmt")
- "p<N>" format using 'port-id' DT property
- "p<N>" format using ethernet alias index as fallback

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
---
 .../stmicro/stmmac/dwmac-renesas-gbeth.c      | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
index bc7bb975803ca..5acb65b0e4f06 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
@@ -16,7 +16,9 @@
 #include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/module.h>
+#include <linux/netdevice.h>
 #include <linux/of.h>
+#include <linux/of_net.h>
 #include <linux/pcs-rzn1-miic.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
@@ -91,6 +93,57 @@ static struct phylink_pcs *renesas_gmac_select_pcs(struct stmmac_priv *priv,
 	return priv->hw->phylink_pcs;
 }
 
+static int renesas_gbeth_get_port_id(struct device *dev)
+{
+	int port_id;
+
+	if (!device_property_read_u32(dev, "renesas,port-id", &port_id))
+		return port_id;
+
+	port_id = of_alias_get_id(dev_of_node(dev), "ethernet");
+
+	return port_id < 0 ? 0 : port_id;
+}
+
+static int renesas_gbeth_get_phys_port_name(struct net_device *ndev,
+					    char *name, size_t len)
+{
+	struct stmmac_priv *priv = netdev_priv(ndev);
+	struct renesas_gbeth *gbeth = priv->plat->bsp_priv;
+	const char *port_name;
+
+	if (!device_property_read_string(gbeth->dev, "renesas,port-name", &port_name))
+		return snprintf(name, len, "%s", port_name) >= len ? -EINVAL : 0;
+
+	return snprintf(name, len, "p%d", renesas_gbeth_get_port_id(gbeth->dev)) >= len ? -EINVAL : 0;
+}
+
+static int renesas_gbeth_get_phys_port_id(struct net_device *ndev,
+					  struct netdev_phys_item_id *ppid)
+{
+	struct stmmac_priv *priv = netdev_priv(ndev);
+	struct renesas_gbeth *gbeth = priv->plat->bsp_priv;
+	u8 *id = ppid->id;
+
+	if (ndev->addr_assign_type == NET_ADDR_PERM) {
+		memcpy(id, ndev->perm_addr, ETH_ALEN);
+	} else {
+		/* Fallback: Renesas OUI prefix (74:90:50) */
+		id[0] = 0x74;
+		id[1] = 0x90;
+		id[2] = 0x50;
+		id[3] = 0x00;
+		id[4] = 0x00;
+		id[5] = 0x00;
+	}
+
+	id[6] = renesas_gbeth_get_port_id(gbeth->dev) & 0xff;
+	id[7] = 0x00;
+	ppid->id_len = 8;
+
+	return 0;
+}
+
 static int renesas_gbeth_init(struct platform_device *pdev, void *priv)
 {
 	struct plat_stmmacenet_data *plat_dat;
@@ -194,6 +247,9 @@ static int renesas_gbeth_probe(struct platform_device *pdev)
 		plat_dat->select_pcs = renesas_gmac_select_pcs;
 	}
 
+	plat_dat->get_phys_port_id = renesas_gbeth_get_phys_port_id;
+	plat_dat->get_phys_port_name = renesas_gbeth_get_phys_port_name;
+
 	return devm_stmmac_pltfr_probe(pdev, plat_dat, &stmmac_res);
 }
 
-- 
2.25.1

[PATCH net-next 3/3] net: stmmac: dwmac-renesas-gbeth: add physical port identification

[John Madieu]

Implement ndo_get_phys_port_id() and ndo_get_phys_port_name() callbacks
for the Renesas RZ/G3E GBETH driver.

The port ID is an 8-byte identifier constructed from:
- Permanent MAC address if available (addr_assign_type == NET_ADDR_PERM)
- Renesas OUI (74:90:50) as fallback for random/generated MACs
- Port index from 'port-id' DT property or ethernet alias

The port name resolution follows this hierarchy:
- 'port-name' DT property if specified (allows custom names like "mgmt")
- "p<N>" format using 'port-id' DT property
- "p<N>" format using ethernet alias index as fallback

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
---
 .../stmicro/stmmac/dwmac-renesas-gbeth.c      | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
index bc7bb975803ca..5acb65b0e4f06 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
@@ -16,7 +16,9 @@
 #include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/module.h>
+#include <linux/netdevice.h>
 #include <linux/of.h>
+#include <linux/of_net.h>
 #include <linux/pcs-rzn1-miic.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
@@ -91,6 +93,57 @@ static struct phylink_pcs *renesas_gmac_select_pcs(struct stmmac_priv *priv,
 	return priv->hw->phylink_pcs;
 }
 
+static int renesas_gbeth_get_port_id(struct device *dev)
+{
+	int port_id;
+
+	if (!device_property_read_u32(dev, "renesas,port-id", &port_id))
+		return port_id;
+
+	port_id = of_alias_get_id(dev_of_node(dev), "ethernet");
+
+	return port_id < 0 ? 0 : port_id;
+}
+
+static int renesas_gbeth_get_phys_port_name(struct net_device *ndev,
+					    char *name, size_t len)
+{
+	struct stmmac_priv *priv = netdev_priv(ndev);
+	struct renesas_gbeth *gbeth = priv->plat->bsp_priv;
+	const char *port_name;
+
+	if (!device_property_read_string(gbeth->dev, "renesas,port-name", &port_name))
+		return snprintf(name, len, "%s", port_name) >= len ? -EINVAL : 0;
+
+	return snprintf(name, len, "p%d", renesas_gbeth_get_port_id(gbeth->dev)) >= len ? -EINVAL : 0;
+}
+
+static int renesas_gbeth_get_phys_port_id(struct net_device *ndev,
+					  struct netdev_phys_item_id *ppid)
+{
+	struct stmmac_priv *priv = netdev_priv(ndev);
+	struct renesas_gbeth *gbeth = priv->plat->bsp_priv;
+	u8 *id = ppid->id;
+
+	if (ndev->addr_assign_type == NET_ADDR_PERM) {
+		memcpy(id, ndev->perm_addr, ETH_ALEN);
+	} else {
+		/* Fallback: Renesas OUI prefix (74:90:50) */
+		id[0] = 0x74;
+		id[1] = 0x90;
+		id[2] = 0x50;
+		id[3] = 0x00;
+		id[4] = 0x00;
+		id[5] = 0x00;
+	}
+
+	id[6] = renesas_gbeth_get_port_id(gbeth->dev) & 0xff;
+	id[7] = 0x00;
+	ppid->id_len = 8;
+
+	return 0;
+}
+
 static int renesas_gbeth_init(struct platform_device *pdev, void *priv)
 {
 	struct plat_stmmacenet_data *plat_dat;
@@ -194,6 +247,9 @@ static int renesas_gbeth_probe(struct platform_device *pdev)
 		plat_dat->select_pcs = renesas_gmac_select_pcs;
 	}
 
+	plat_dat->get_phys_port_id = renesas_gbeth_get_phys_port_id;
+	plat_dat->get_phys_port_name = renesas_gbeth_get_phys_port_name;
+
 	return devm_stmmac_pltfr_probe(pdev, plat_dat, &stmmac_res);
 }
 
-- 
2.25.1

[PATCH net-next 3/3] net: stmmac: dwmac-renesas-gbeth: add physical port identification

[John Madieu]

Implement ndo_get_phys_port_id() and ndo_get_phys_port_name() callbacks
for the Renesas RZ/G3E GBETH driver.

The port ID is an 8-byte identifier constructed from:
- Permanent MAC address if available (addr_assign_type == NET_ADDR_PERM)
- Renesas OUI (74:90:50) as fallback for random/generated MACs
- Port index from 'port-id' DT property or ethernet alias

The port name resolution follows this hierarchy:
- 'port-name' DT property if specified (allows custom names like "mgmt")
- "p<N>" format using 'port-id' DT property
- "p<N>" format using ethernet alias index as fallback

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
---
 .../stmicro/stmmac/dwmac-renesas-gbeth.c      | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
index bc7bb975803ca..5acb65b0e4f06 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-renesas-gbeth.c
@@ -16,7 +16,9 @@
 #include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/module.h>
+#include <linux/netdevice.h>
 #include <linux/of.h>
+#include <linux/of_net.h>
 #include <linux/pcs-rzn1-miic.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
@@ -91,6 +93,57 @@ static struct phylink_pcs *renesas_gmac_select_pcs(struct stmmac_priv *priv,
 	return priv->hw->phylink_pcs;
 }
 
+static int renesas_gbeth_get_port_id(struct device *dev)
+{
+	int port_id;
+
+	if (!device_property_read_u32(dev, "renesas,port-id", &port_id))
+		return port_id;
+
+	port_id = of_alias_get_id(dev_of_node(dev), "ethernet");
+
+	return port_id < 0 ? 0 : port_id;
+}
+
+static int renesas_gbeth_get_phys_port_name(struct net_device *ndev,
+					    char *name, size_t len)
+{
+	struct stmmac_priv *priv = netdev_priv(ndev);
+	struct renesas_gbeth *gbeth = priv->plat->bsp_priv;
+	const char *port_name;
+
+	if (!device_property_read_string(gbeth->dev, "renesas,port-name", &port_name))
+		return snprintf(name, len, "%s", port_name) >= len ? -EINVAL : 0;
+
+	return snprintf(name, len, "p%d", renesas_gbeth_get_port_id(gbeth->dev)) >= len ? -EINVAL : 0;
+}
+
+static int renesas_gbeth_get_phys_port_id(struct net_device *ndev,
+					  struct netdev_phys_item_id *ppid)
+{
+	struct stmmac_priv *priv = netdev_priv(ndev);
+	struct renesas_gbeth *gbeth = priv->plat->bsp_priv;
+	u8 *id = ppid->id;
+
+	if (ndev->addr_assign_type == NET_ADDR_PERM) {
+		memcpy(id, ndev->perm_addr, ETH_ALEN);
+	} else {
+		/* Fallback: Renesas OUI prefix (74:90:50) */
+		id[0] = 0x74;
+		id[1] = 0x90;
+		id[2] = 0x50;
+		id[3] = 0x00;
+		id[4] = 0x00;
+		id[5] = 0x00;
+	}
+
+	id[6] = renesas_gbeth_get_port_id(gbeth->dev) & 0xff;
+	id[7] = 0x00;
+	ppid->id_len = 8;
+
+	return 0;
+}
+
 static int renesas_gbeth_init(struct platform_device *pdev, void *priv)
 {
 	struct plat_stmmacenet_data *plat_dat;
@@ -194,6 +247,9 @@ static int renesas_gbeth_probe(struct platform_device *pdev)
 		plat_dat->select_pcs = renesas_gmac_select_pcs;
 	}
 
+	plat_dat->get_phys_port_id = renesas_gbeth_get_phys_port_id;
+	plat_dat->get_phys_port_name = renesas_gbeth_get_phys_port_name;
+
 	return devm_stmmac_pltfr_probe(pdev, plat_dat, &stmmac_res);
 }
 
-- 
2.25.1

Re: [PATCH net-next 1/3] net: stmmac: add physical port identification support

[Russell King (Oracle)]

On Thu, Dec 04, 2025 at 04:31:20PM +0000, John Madieu wrote:
> +static int stmmac_get_phys_port_name(struct net_device *dev,
> +				     char *name, size_t len)
> +{
> +	struct stmmac_priv *priv = netdev_priv(dev);
> +
> +	/* Allow glue driver to override */
> +	if (priv->plat->get_phys_port_name)
> +		return priv->plat->get_phys_port_name(dev, name, len);
> +
> +	/* Default: use bus_id as port identifier */
> +	return snprintf(name, len, "p%d", priv->plat->bus_id) >= len ? -EINVAL : 0;

priv->plat->bus_id may not be stable - for example, if a SoC describes
two stmmac ethernet, but omits the ethernet aliases, then plat->bus_id
is assigned in order that stmmac_probe_config_dt() is called for each
device.

How important is it that the phys_port_name is stable across boots?
If it should be stable, then I think we should not report it if we end
up falling back to the "assign in order of stmmac_probe_config_dt()".

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH net-next 3/3] net: stmmac: dwmac-renesas-gbeth: add physical port identification

[Russell King (Oracle)]

On Thu, Dec 04, 2025 at 04:31:22PM +0000, John Madieu wrote:
> +static int renesas_gbeth_get_port_id(struct device *dev)
> +{
> +	int port_id;
> +
> +	if (!device_property_read_u32(dev, "renesas,port-id", &port_id))
> +		return port_id;
> +
> +	port_id = of_alias_get_id(dev_of_node(dev), "ethernet");
> +
> +	return port_id < 0 ? 0 : port_id;
> +}

You fall back to the ethernet alias, which is essentially what
devm_stmmac_probe_config_dt() will assign to plat->bus_id. So, is
there any reason we can't just use plat->bus_id ? Why do we need a
special property?

I really don't like the idea that, with the proposal here, we'll
likely see the stmmac platform glue spawn more platform specific
code. This doesn't scale.

So, the next question: should there be a standard way to describe
these attributes, rather than having lots of vendor specific
properties describing the same information? Should this be part
of the generic binding, iow
Documentation/devicetree/bindings/net/ethernet-controller.yaml ?

-- 
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