[PATCH v5 net-next 2/5] net: dsa: notify drivers of MAC address changes on user ports

[Lukasz Majewski]

From: Vladimir Oltean <vladimir.oltean@xxxxxxx>

In some cases, drivers may need to veto the changing of a MAC address on
a user port. Such is the case with KSZ9477 when it offloads a HSR device,
because it programs the MAC address of multiple ports to a shared
hardware register. Those ports need to have equal MAC addresses for the
lifetime of the HSR offload.

Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Signed-off-by: Lukasz Majewski <lukma@xxxxxxx>

---
Changes for v5:
- New patch
---
 include/net/dsa.h | 10 ++++++++++
 net/dsa/slave.c   |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 426724808e76..d98439ea6146 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -969,6 +969,16 @@ struct dsa_switch_ops {
 			       struct phy_device *phy);
 	void	(*port_disable)(struct dsa_switch *ds, int port);
 
+
+	/*
+	 * Notification for MAC address changes on user ports. Drivers can
+	 * currently only veto operations. They should not use the method to
+	 * program the hardware, since the operation is not rolled back in case
+	 * of other errors.
+	 */
+	int	(*port_set_mac_address)(struct dsa_switch *ds, int port,
+					const unsigned char *addr);
+
 	/*
 	 * Compatibility between device trees defining multiple CPU ports and
 	 * drivers which are not OK to use by default the numerically smallest
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 2b3d89b77121..4c3e502d7e16 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -457,6 +457,13 @@ static int dsa_slave_set_mac_address(struct net_device *dev, void *a)
 	if (!is_valid_ether_addr(addr->sa_data))
 		return -EADDRNOTAVAIL;
 
+	if (ds->ops->port_set_mac_address) {
+		err = ds->ops->port_set_mac_address(ds, dp->index,
+						    addr->sa_data);
+		if (err)
+			return err;
+	}
+
 	/* If the port is down, the address isn't synced yet to hardware or
 	 * to the DSA master, so there is nothing to change.
 	 */
-- 
2.20.1