From a4604b3cde1c8857e78059ef2d49207e28b9df25 Mon Sep 17 00:00:00 2001
From: Ansuel Smith <ansuelsmth@gmail.com>
Date: Sat, 11 Sep 2021 17:50:09 +0200
Subject: [PATCH] net: dsa: qca8k: fix kernel panic with legacy mdio mapping
Git-commit: ce062a0adbfe933b1932235fdfd874c4c91d1bb0
Patch-mainline: v5.15-rc2
References: stable-5.14.7

[ Upstream commit ce062a0adbfe933b1932235fdfd874c4c91d1bb0 ]

When the mdio legacy mapping is used the mii_bus priv registered by DSA
refer to the dsa switch struct instead of the qca8k_priv struct and
causes a kernel panic. Create dedicated function when the internal
dedicated mdio driver is used to properly handle the 2 different
implementation.

Fixes: 759bafb8a322 ("net: dsa: qca8k: add support for internal phy and internal mdio")
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/dsa/qca8k.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index 1f63f50f73f1..bda5a9bf4f52 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -643,10 +643,8 @@ qca8k_mdio_busy_wait(struct mii_bus *bus, u32 reg, u32 mask)
 }
 
 static int
-qca8k_mdio_write(struct mii_bus *salve_bus, int phy, int regnum, u16 data)
+qca8k_mdio_write(struct mii_bus *bus, int phy, int regnum, u16 data)
 {
-	struct qca8k_priv *priv = salve_bus->priv;
-	struct mii_bus *bus = priv->bus;
 	u16 r1, r2, page;
 	u32 val;
 	int ret;
@@ -682,10 +680,8 @@ qca8k_mdio_write(struct mii_bus *salve_bus, int phy, int regnum, u16 data)
 }
 
 static int
-qca8k_mdio_read(struct mii_bus *salve_bus, int phy, int regnum)
+qca8k_mdio_read(struct mii_bus *bus, int phy, int regnum)
 {
-	struct qca8k_priv *priv = salve_bus->priv;
-	struct mii_bus *bus = priv->bus;
 	u16 r1, r2, page;
 	u32 val;
 	int ret;
@@ -726,6 +722,24 @@ qca8k_mdio_read(struct mii_bus *salve_bus, int phy, int regnum)
 	return ret;
 }
 
+static int
+qca8k_internal_mdio_write(struct mii_bus *slave_bus, int phy, int regnum, u16 data)
+{
+	struct qca8k_priv *priv = slave_bus->priv;
+	struct mii_bus *bus = priv->bus;
+
+	return qca8k_mdio_write(bus, phy, regnum, data);
+}
+
+static int
+qca8k_internal_mdio_read(struct mii_bus *slave_bus, int phy, int regnum)
+{
+	struct qca8k_priv *priv = slave_bus->priv;
+	struct mii_bus *bus = priv->bus;
+
+	return qca8k_mdio_read(bus, phy, regnum);
+}
+
 static int
 qca8k_phy_write(struct dsa_switch *ds, int port, int regnum, u16 data)
 {
@@ -775,8 +789,8 @@ qca8k_mdio_register(struct qca8k_priv *priv, struct device_node *mdio)
 
 	bus->priv = (void *)priv;
 	bus->name = "qca8k slave mii";
-	bus->read = qca8k_mdio_read;
-	bus->write = qca8k_mdio_write;
+	bus->read = qca8k_internal_mdio_read;
+	bus->write = qca8k_internal_mdio_write;
 	snprintf(bus->id, MII_BUS_ID_SIZE, "qca8k-%d",
 		 ds->index);
 
-- 
2.26.2