[PATCH v1 2/2] net: phy: micrel: port clock select support

[Trent Piepho]

On Tue, Oct 12, 2021 at 3:10 AM Oleksij Rempel <o.rempel at pengutronix.de> wrote:
>
> Port devicetree based clock select support from kernel micrel driver (v5.15-rc1).
> This support is needed to make netboot work on boards with PHY node and
> "rmii-ref" property.

Existing boards use a phy fixup to handle this case, e.g. fsl,imx6ull-14x14-evk:

static int nxp_imx6ull_evk_init(void)
{
         phy_register_fixup_for_uid(PHY_ID_KSZ8081, MICREL_PHY_ID_MASK,
                       ksz8081_phy_fixup);

static int ksz8081_phy_fixup(struct phy_device *dev)
{
       phy_write(dev, 0x1f, 0x8190);
       phy_write(dev, 0x16, 0x202);

I thought about extending micrel driver like this when I added support
for NXP imx6ul (single L, not double L as above) dev kit but decided
it was a lot of code for what ends up being one register write for
boards using a ksz8081 and the barebox phy fixup concept, which
handles this in only a couple lines, was easier.

Also look at ks8051_config_init(), it checks phydev->dev_flags to set
this same bit.  But AFAICT, dev_flags is not used in Barebox.

> +/* PHY Control 2 / PHY Control (if no PHY Control 1) */
> +#define MII_KSZPHY_CTRL_2                      0x1f
> +#define KSZPHY_RMII_REF_CLK_SEL                        BIT(7)

These are already in this file as MII_KSZPHY_CTRL and KSZ8051_RMII_50MHZ_CLK.

> +struct kszphy_type {
> +       bool has_rmii_ref_clk_sel;
> +};
> +
> +struct kszphy_priv {
> +       const struct kszphy_type *type;

type does not appear to be used from the state struct.

> +       bool rmii_ref_clk_sel;
> +       bool rmii_ref_clk_sel_val;

All you need is a single flag to indicate the KSZ8051_RMII_50MHZ_CLK
bit should be set after a reset.  Otherwise it can be left unset,
which is the default value.

> +static const struct kszphy_type ksz8081_type = {
> +       .has_rmii_ref_clk_sel   = true,
> +};

Note that not just KSZ8081 has this bit.  Also KSZ8021, KSZ8031, and
KSZ8051, which has the existing different method to handle it, as
described earlier.

> +static int kszphy_rmii_clk_sel(struct phy_device *phydev, bool val)
> +{
> +       int ctrl;
> +
> +       ctrl = phy_read(phydev, MII_KSZPHY_CTRL);
> +       if (ctrl < 0)
> +               return ctrl;
> +
> +       if (val)
> +               ctrl |= KSZPHY_RMII_REF_CLK_SEL;
> +       else
> +               ctrl &= ~KSZPHY_RMII_REF_CLK_SEL;
> +
> +       return phy_write(phydev, MII_KSZPHY_CTRL, ctrl);
> +}

phy_set_bits(phydev, MII_KSZPHY_CTRL, KSZ8051_RMII_50MHZ_CLK);

> +
> +       /* Support legacy board-file configuration */
> +       if (phydev->dev_flags & MICREL_PHY_50MHZ_CLK) {
> +               priv->rmii_ref_clk_sel = true;
> +               priv->rmii_ref_clk_sel_val = true;
> +       }

Can't code in ksz8051_config_init be removed then?