net: dsa: qca8k: fix kernel panic with legacy mdio mapping

When the mdio legacy mapping is used the mii_bus priv registred by DSA
refer to the dsa switch struct instead of the qca8k_priv struct and
cause a kernel panic. Create dedicated function when the internal
dedicated mdio driver is used to proprely 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>
---
 drivers/net/dsa/qca8k.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

On 9/11/2021 08:07, Ansuel Smith wrote:
> When the mdio legacy mapping is used the mii_bus priv registred by DSA

typo: registered

> refer to the dsa switch struct instead of the qca8k_priv struct and
> cause a kernel panic.

typo: causes

> Create dedicated function when the internal
> dedicated mdio driver is used to proprely handle the 2 different
> implementation.

typo: properly

> 
> Fixes: 759bafb8a322 ("net: dsa: qca8k: add support for internal phy and internal mdio")
> Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> ---
>   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..a701323daf72 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 *salve_bus, int phy, int regnum, u16 data)
> +{
> +	struct qca8k_priv *priv = salve_bus->priv;

You are only moving code here but while at it, mind fixing that typo?

> +	struct mii_bus *bus = priv->bus;
> +
> +	return qca8k_mdio_write(bus, phy, regnum, data);
> +}
> +
> +static int
> +qca8k_internal_mdio_read(struct mii_bus *salve_bus, int phy, int regnum)
> +{
> +	struct qca8k_priv *priv = salve_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);
>   
>

On Sat, Sep 11, 2021 at 05:36:40PM +0200, Ansuel Smith wrote:
> > > +static int
> > > +qca8k_internal_mdio_write(struct mii_bus *salve_bus, int phy, int regnum, u16 data)
> > > +{
> > > +	struct qca8k_priv *priv = salve_bus->priv;
> > 
> > You are only moving code here but while at it, mind fixing that typo?
> >
> 
> I think I didn't understand what you mean here.
> Sure I will fix the typo and sorry about it.
> Aside from that anything wrong with the 2 new function or there is a
> better fix that I can't think of.

"salve" is "hello" in Italian, and even though that is a greeting,
surely that is not what was meant, but rather "slave". So even though
that is less positive, it is at least a technical term with a clear
meaning, so I think Florian's request was to replace "salve" with
"slave" while you are moving the code anyway.