netdev - [PATCH net-next 12/14] net: stmmac: add support for reading inband SGMII status

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Message-Id: <E1vg4wc-00000003SGl-1dZi@rmk-PC.armlinux.org.uk>
Date: Wed, 14 Jan 2026 17:46:10 +0000
From: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
To: Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-arm-msm@...r.kernel.org,
	linux-phy@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Mohd Ayaan Anwar <mohd.anwar@....qualcomm.com>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>,
	Vinod Koul <vkoul@...nel.org>
Subject: [PATCH net-next 12/14] net: stmmac: add support for reading inband
 SGMII status

Report the link, speed and duplex for SGMII links, read from the
SGMII, RGMII and SMII status and control register.

Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
 .../net/ethernet/stmicro/stmmac/stmmac_pcs.c  | 44 ++++++++++++++++++-
 .../net/ethernet/stmicro/stmmac/stmmac_pcs.h  |  4 ++
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.c
index 73fc56ce5e55..12fc5038d913 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.c
@@ -17,6 +17,16 @@
 #define GMAC_ANE_LPA	0x0c	/* ANE link partener ability */
 #define GMAC_TBI	0x14	/* TBI extend status */
 
+/*
+ * RGSMII status bitfield definitions.
+ */
+#define GMAC_RGSMIII_LNKMOD		BIT(0)
+#define GMAC_RGSMIII_SPEED_MASK		GENMASK(2, 1)
+#define GMAC_RGSMIII_SPEED_125		2
+#define GMAC_RGSMIII_SPEED_25		1
+#define GMAC_RGSMIII_SPEED_2_5		0
+#define GMAC_RGSMIII_LNKSTS		BIT(3)
+
 static enum ethtool_link_mode_bit_indices dwmac_hd_mode_bits[] = {
 	ETHTOOL_LINK_MODE_10baseT_Half_BIT,
 	ETHTOOL_LINK_MODE_100baseT_Half_BIT,
@@ -97,7 +107,7 @@ static void dwmac_integrated_pcs_get_state(struct phylink_pcs *pcs,
 					   struct phylink_link_state *state)
 {
 	struct stmmac_pcs *spcs = phylink_pcs_to_stmmac_pcs(pcs);
-	u32 status, lpa;
+	u32 status, lpa, rgsmii;
 
 	status = readl(spcs->base + GMAC_AN_STATUS);
 
@@ -111,7 +121,35 @@ static void dwmac_integrated_pcs_get_state(struct phylink_pcs *pcs,
 
 		phylink_mii_c22_pcs_decode_state(state, neg_mode, status, lpa);
 	} else {
-		state->link = false;
+		rgsmii = field_get(spcs->rgsmii_status_mask,
+				   readl(spcs->rgsmii));
+		state->link = !!(status & GMAC_RGSMIII_LNKSTS);
+
+		if (state->link && neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED) {
+			/* FIXME: fill in speed and duplex. This requires the
+			 * contents of the dwmac1000 GMAC_RGSMIIIS or dwmac4
+			 * GMAC_PHYIF_CONTROL_STATUS register.
+			 */
+			state->duplex = rgsmii & GMAC_RGSMIII_LNKMOD ?
+					DUPLEX_FULL : DUPLEX_HALF;
+			switch (FIELD_GET(GMAC_RGSMIII_SPEED_MASK, rgsmii)) {
+			case GMAC_RGSMIII_SPEED_2_5:
+				state->speed = SPEED_10;
+				break;
+
+			case GMAC_RGSMIII_SPEED_25:
+				state->speed = SPEED_100;
+				break;
+
+			case GMAC_RGSMIII_SPEED_125:
+				state->speed = SPEED_1000;
+				break;
+
+			default:
+				state->link = false;
+				break;
+			}
+		}
 	}
 }
 
@@ -205,6 +243,8 @@ int stmmac_integrated_pcs_init(struct stmmac_priv *priv,
 
 	spcs->priv = priv;
 	spcs->base = priv->ioaddr + pcs_info->pcs_offset;
+	spcs->rgsmii = priv->ioaddr + pcs_info->rgsmii_offset;
+	spcs->rgsmii_status_mask = pcs_info->rgsmii_status_mask;
 	spcs->int_mask = pcs_info->int_mask;
 	spcs->pcs.ops = &dwmac_integrated_pcs_ops;
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h b/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
index a7c71f40f952..f9e7a7ed840b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
@@ -29,12 +29,16 @@ struct stmmac_priv;
 
 struct stmmac_pcs_info {
 	unsigned int pcs_offset;
+	unsigned int rgsmii_offset;
+	u32 rgsmii_status_mask;
 	u32 int_mask;
 };
 
 struct stmmac_pcs {
 	struct stmmac_priv *priv;
 	void __iomem *base;
+	void __iomem *rgsmii;
+	u32 rgsmii_status_mask;
 	u32 int_mask;
 	phy_interface_t interface;
 	struct phylink_pcs pcs;
-- 
2.47.3