netdev - [RFC PATCH 07/10] net: dsa: b53: prevent GMII_PORT_OVERRIDE

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Message-Id: <20250531101308.155757-8-noltari@gmail.com>
Date: Sat, 31 May 2025 12:13:05 +0200
From: Álvaro Fernández Rojas <noltari@...il.com>
To: jonas.gorski@...il.com,
	florian.fainelli@...adcom.com,
	andrew@...n.ch,
	olteanv@...il.com,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	vivien.didelot@...il.com,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	dgcbueu@...il.com
Cc: Álvaro Fernández Rojas <noltari@...il.com>
Subject: [RFC PATCH 07/10] net: dsa: b53: prevent GMII_PORT_OVERRIDE_CTRL access on BCM5325

BCM5325 doesn't implement GMII_PORT_OVERRIDE_CTRL register so we should
avoid reading or writing it.
PORT_OVERRIDE_RX_FLOW and PORT_OVERRIDE_TX_FLOW aren't defined on BCM5325
and we should use PORT_OVERRIDE_LP_FLOW_25 instead.

Fixes: 5e004460f874 ("net: dsa: b53: Add helper to set link parameters")
Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
---
 drivers/net/dsa/b53/b53_common.c | 21 +++++++++++++++++----
 drivers/net/dsa/b53/b53_regs.h   |  1 +
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index fd0752100df8..387e1e7ec749 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -1278,6 +1278,8 @@ static void b53_force_link(struct b53_device *dev, int port, int link)
 	if (port == dev->imp_port) {
 		off = B53_PORT_OVERRIDE_CTRL;
 		val = PORT_OVERRIDE_EN;
+	} else if (is5325(dev)) {
+		return;
 	} else {
 		off = B53_GMII_PORT_OVERRIDE_CTRL(port);
 		val = GMII_PO_EN;
@@ -1302,6 +1304,8 @@ static void b53_force_port_config(struct b53_device *dev, int port,
 	if (port == dev->imp_port) {
 		off = B53_PORT_OVERRIDE_CTRL;
 		val = PORT_OVERRIDE_EN;
+	} else if (is5325(dev)) {
+		return;
 	} else {
 		off = B53_GMII_PORT_OVERRIDE_CTRL(port);
 		val = GMII_PO_EN;
@@ -1332,10 +1336,19 @@ static void b53_force_port_config(struct b53_device *dev, int port,
 		return;
 	}
 
-	if (rx_pause)
-		reg |= PORT_OVERRIDE_RX_FLOW;
-	if (tx_pause)
-		reg |= PORT_OVERRIDE_TX_FLOW;
+	if (rx_pause) {
+		if (is5325(dev))
+			reg |= PORT_OVERRIDE_LP_FLOW_25;
+		else
+			reg |= PORT_OVERRIDE_RX_FLOW;
+	}
+
+	if (tx_pause) {
+		if (is5325(dev))
+			reg |= PORT_OVERRIDE_LP_FLOW_25;
+		else
+			reg |= PORT_OVERRIDE_TX_FLOW;
+	}
 
 	b53_write8(dev, B53_CTRL_PAGE, off, reg);
 }
diff --git a/drivers/net/dsa/b53/b53_regs.h b/drivers/net/dsa/b53/b53_regs.h
index 896684d7f594..ab15f36a135a 100644
--- a/drivers/net/dsa/b53/b53_regs.h
+++ b/drivers/net/dsa/b53/b53_regs.h
@@ -95,6 +95,7 @@
 #define   PORT_OVERRIDE_SPEED_10M	(0 << PORT_OVERRIDE_SPEED_S)
 #define   PORT_OVERRIDE_SPEED_100M	(1 << PORT_OVERRIDE_SPEED_S)
 #define   PORT_OVERRIDE_SPEED_1000M	(2 << PORT_OVERRIDE_SPEED_S)
+#define   PORT_OVERRIDE_LP_FLOW_25	BIT(3) /* BCM5325 only */
 #define   PORT_OVERRIDE_RV_MII_25	BIT(4) /* BCM5325 only */
 #define   PORT_OVERRIDE_RX_FLOW		BIT(4)
 #define   PORT_OVERRIDE_TX_FLOW		BIT(5)
-- 
2.39.5