[PATCH 3/3] net: stmmac: dwmac-socfpga: Add mac-mode DT property support

[muhammad.nazim.amirul.nazle.asmade at altera.com]

From: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade at altera.com>

Russell King's commit de696c63c1dc ("net: stmmac: socfpga: convert to
use phy_interface") replaced mac_interface with phy_interface in
socfpga_get_plat_phymode(), noting that no upstream DTS files set the
"mac-mode" property, making the two values identical.

The Agilex5 SoCDK TSN Config2 board is an exception: its gmac1 TSN
port uses GMII internally in the MAC while the PHY-side interface is
RGMII, so mac-mode and phy-mode differ. Without restoring mac_interface
support, the MAC is configured with RGMII instead of GMII, causing
connectivity failures on this board.

Add socfpga_of_get_mac_mode() to read the optional "mac-mode" DT
property and store it in a new mac_interface field. When the property
is absent, mac_interface falls back to phy_interface, preserving
the existing behaviour for all other boards.

Fixes: de696c63c1dc ("net: stmmac: socfpga: convert to use phy_interface")
Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade at altera.com>
---
 .../ethernet/stmicro/stmmac/dwmac-socfpga.c   | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
index 1d7f0a57d288..6a6837c4a414 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
@@ -69,12 +69,30 @@ struct socfpga_dwmac {
 	void __iomem *tse_pcs_base;
 	void __iomem *sgmii_adapter_base;
 	bool f2h_ptp_ref_clk;
+	phy_interface_t mac_interface;
 	const struct socfpga_dwmac_ops *ops;
 };
 
+static int socfpga_of_get_mac_mode(struct device_node *np)
+{
+	const char *pm;
+	int err, i;
+
+	err = of_property_read_string(np, "mac-mode", &pm);
+	if (err < 0)
+		return err;
+
+	for (i = 0; i < PHY_INTERFACE_MODE_MAX; i++) {
+		if (!strcasecmp(pm, phy_modes(i)))
+			return i;
+	}
+
+	return -ENODEV;
+}
+
 static phy_interface_t socfpga_get_plat_phymode(struct socfpga_dwmac *dwmac)
 {
-	return dwmac->plat_dat->phy_interface;
+	return dwmac->mac_interface;
 }
 
 static void socfpga_sgmii_config(struct socfpga_dwmac *dwmac, bool enable)
@@ -650,6 +668,9 @@ static int socfpga_dwmac_probe(struct platform_device *pdev)
 	plat_dat->pcs_exit = socfpga_dwmac_pcs_exit;
 	plat_dat->select_pcs = socfpga_dwmac_select_pcs;
 
+	ret = socfpga_of_get_mac_mode(pdev->dev.of_node);
+	dwmac->mac_interface = ret < 0 ? plat_dat->phy_interface : ret;
+
 	ops->setup_plat_dat(dwmac);
 
 	return devm_stmmac_pltfr_probe(pdev, plat_dat, &stmmac_res);
-- 
2.43.7