Implement port isolation support via the Protected Ports register.

Protected ports can only communicate with unprotected ports, but not
with each other, matching the expected behaviour of isolated ports.

Tested on BCM963268BU.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
---
 drivers/net/dsa/b53/b53_common.c | 25 ++++++++++++++++++++++++-
 drivers/net/dsa/b53/b53_regs.h   |  4 ++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index 2f846381d5a7..ad4990da9f7c 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -632,6 +632,25 @@ static void b53_port_set_learning(struct b53_device *dev, int port,
 	b53_write16(dev, B53_CTRL_PAGE, B53_DIS_LEARNING, reg);
 }
 
+static void b53_port_set_isolated(struct b53_device *dev, int port,
+				  bool isolated)
+{
+	u8 offset;
+	u16 reg;
+
+	if (is5325(dev))
+		offset = B53_PROTECTED_PORT_SEL_25;
+	else
+		offset = B53_PROTECTED_PORT_SEL;
+
+	b53_read16(dev, B53_CTRL_PAGE, offset, &reg);
+	if (isolated)
+		reg |= BIT(port);
+	else
+		reg &= ~BIT(port);
+	b53_write16(dev, B53_CTRL_PAGE, offset, reg);
+}
+
 static void b53_eee_enable_set(struct dsa_switch *ds, int port, bool enable)
 {
 	struct b53_device *dev = ds->priv;
@@ -652,6 +671,7 @@ int b53_setup_port(struct dsa_switch *ds, int port)
 	b53_port_set_ucast_flood(dev, port, true);
 	b53_port_set_mcast_flood(dev, port, true);
 	b53_port_set_learning(dev, port, false);
+	b53_port_set_isolated(dev, port, false);
 
 	/* Force all traffic to go to the CPU port to prevent the ASIC from
 	 * trying to forward to bridged ports on matching FDB entries, then
@@ -2318,7 +2338,7 @@ int b53_br_flags_pre(struct dsa_switch *ds, int port,
 		     struct netlink_ext_ack *extack)
 {
 	struct b53_device *dev = ds->priv;
-	unsigned long mask = (BR_FLOOD | BR_MCAST_FLOOD);
+	unsigned long mask = (BR_FLOOD | BR_MCAST_FLOOD | BR_ISOLATED);
 
 	if (!is5325(dev))
 		mask |= BR_LEARNING;
@@ -2343,6 +2363,9 @@ int b53_br_flags(struct dsa_switch *ds, int port,
 	if (flags.mask & BR_LEARNING)
 		b53_port_set_learning(ds->priv, port,
 				      !!(flags.val & BR_LEARNING));
+	if (flags.mask & BR_ISOLATED)
+		b53_port_set_isolated(ds->priv, port,
+				      !!(flags.val & BR_ISOLATED));
 
 	return 0;
 }
diff --git a/drivers/net/dsa/b53/b53_regs.h b/drivers/net/dsa/b53/b53_regs.h
index 309fe0e46dad..c16b3e3e8227 100644
--- a/drivers/net/dsa/b53/b53_regs.h
+++ b/drivers/net/dsa/b53/b53_regs.h
@@ -120,6 +120,10 @@
 #define B53_SWITCH_CTRL			0x22
 #define  B53_MII_DUMB_FWDG_EN		BIT(6)
 
+/* Protected Port Selection (16 bit) */
+#define B53_PROTECTED_PORT_SEL		0x24
+#define B53_PROTECTED_PORT_SEL_25	0x26
+
 /* (16 bit) */
 #define B53_UC_FLOOD_MASK		0x32
 #define B53_MC_FLOOD_MASK		0x34

base-commit: 18a7e218cfcdca6666e1f7356533e4c988780b57
-- 
2.43.0

On 10/13/25 08:28, Jonas Gorski wrote:
> Implement port isolation support via the Protected Ports register.
> 
> Protected ports can only communicate with unprotected ports, but not
> with each other, matching the expected behaviour of isolated ports.
> 
> Tested on BCM963268BU.
> 
> Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian