From 804dbd251ef5c3edd4ff14cc38b6d56588451a50 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Tue, 5 Apr 2022 14:02:33 +0200
Subject: net: phy: mscc-miim: reject clause 45 register accesses

From: Michael Walle <michael@walle.cc>

[ Upstream commit 8d90991e5bf7fdb9f264f5f579d18969913054b7 ]

The driver doesn't support clause 45 register access yet, but doesn't
check if the access is a c45 one either. This leads to spurious register
reads and writes. Add the check.

Fixes: 542671fe4d86 ("net: phy: mscc-miim: Add MDIO driver")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/mdio/mdio-mscc-miim.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/mdio/mdio-mscc-miim.c b/drivers/net/mdio/mdio-mscc-miim.c
index 17f98f609ec8..5070ca2f2637 100644
--- a/drivers/net/mdio/mdio-mscc-miim.c
+++ b/drivers/net/mdio/mdio-mscc-miim.c
@@ -76,6 +76,9 @@ static int mscc_miim_read(struct mii_bus *bus, int mii_id, int regnum)
 	u32 val;
 	int ret;
 
+	if (regnum & MII_ADDR_C45)
+		return -EOPNOTSUPP;
+
 	ret = mscc_miim_wait_pending(bus);
 	if (ret)
 		goto out;
@@ -105,6 +108,9 @@ static int mscc_miim_write(struct mii_bus *bus, int mii_id,
 	struct mscc_miim_dev *miim = bus->priv;
 	int ret;
 
+	if (regnum & MII_ADDR_C45)
+		return -EOPNOTSUPP;
+
 	ret = mscc_miim_wait_pending(bus);
 	if (ret < 0)
 		goto out;
-- 
2.35.1