[PATCH v1 1/3] net: port support for microchip SMI0 MDIO bus

[Sascha Hauer]

On Tue, Sep 20, 2022 at 02:55:31PM +0200, Oleksij Rempel wrote:
> SMI0 is a mangled version of MDIO. The main low level difference is
> the MDIO C22 OP code is always 0, not 0x2 or 0x1 for Read/Write. The
> read/write information is instead encoded in the PHY address.
> 
> Extend the bit-bang code to allow the op code to be overridden, but
> default to normal C22 values. Add an extra compatible to the mdio-gpio
> driver, and when this compatible is present, set the op codes to 0.
> 
> A higher level driver, sitting on top of the basic MDIO bus driver can
> then implement the rest of the microchip SMI0 odderties.
> 
> This code was ported from the kernel v6.0-rc2.
> 
> Signed-off-by: Oleksij Rempel <o.rempel at pengutronix.de>
> ---
>  drivers/net/phy/mdio-bitbang.c | 8 ++++++--
>  drivers/net/phy/mdio-gpio.c    | 8 ++++++++
>  include/linux/mdio-bitbang.h   | 3 +++
>  3 files changed, 17 insertions(+), 2 deletions(-)

Applied, thanks

Sascha

> 
> diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c
> index 839a7d1eb8..656557589d 100644
> --- a/drivers/net/phy/mdio-bitbang.c
> +++ b/drivers/net/phy/mdio-bitbang.c
> @@ -158,7 +158,7 @@ static int mdiobb_read(struct mii_bus *bus, int phy, int reg)
>  		reg = mdiobb_cmd_addr(ctrl, phy, reg);
>  		mdiobb_cmd(ctrl, MDIO_C45_READ, phy, reg);
>  	} else
> -		mdiobb_cmd(ctrl, MDIO_READ, phy, reg);
> +		mdiobb_cmd(ctrl, ctrl->op_c22_read, phy, reg);
>  
>  	ctrl->ops->set_mdio_dir(ctrl, 0);
>  
> @@ -188,7 +188,7 @@ static int mdiobb_write(struct mii_bus *bus, int phy, int reg, u16 val)
>  		reg = mdiobb_cmd_addr(ctrl, phy, reg);
>  		mdiobb_cmd(ctrl, MDIO_C45_WRITE, phy, reg);
>  	} else
> -		mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg);
> +		mdiobb_cmd(ctrl, ctrl->op_c22_write, phy, reg);
>  
>  	/* send the turnaround (10) */
>  	mdiobb_send_bit(ctrl, 1);
> @@ -219,6 +219,10 @@ struct mii_bus *alloc_mdio_bitbang(struct mdiobb_ctrl *ctrl)
>  	bus->write = mdiobb_write;
>  	bus->reset = mdiobb_reset;
>  	bus->priv = ctrl;
> +	if (!ctrl->override_op_c22) {
> +		ctrl->op_c22_read = MDIO_READ;
> +		ctrl->op_c22_write = MDIO_WRITE;
> +	}
>  
>  	return bus;
>  }
> diff --git a/drivers/net/phy/mdio-gpio.c b/drivers/net/phy/mdio-gpio.c
> index 80d2394f4b..c64f2b3925 100644
> --- a/drivers/net/phy/mdio-gpio.c
> +++ b/drivers/net/phy/mdio-gpio.c
> @@ -193,6 +193,13 @@ static int mdio_gpio_probe(struct device_d *dev)
>  		goto free_mdo;
>  	}
>  
> +	if (np &&
> +	    of_device_is_compatible(np, "microchip,mdio-smi0")) {
> +		info->ctrl.op_c22_read = 0;
> +		info->ctrl.op_c22_write = 0;
> +		info->ctrl.override_op_c22 = 1;
> +	}
> +
>  	bus = alloc_mdio_bitbang(&info->ctrl);
>  	bus->parent = dev;
>  	bus->dev.device_node = np;
> @@ -217,6 +224,7 @@ free_info:
>  
>  static const struct of_device_id gpio_mdio_dt_ids[] = {
>  	{ .compatible = "virtual,mdio-gpio", },
> +	{ .compatible = "microchip,mdio-smi0" },
>  	{ /* sentinel */ }
>  };
>  
> diff --git a/include/linux/mdio-bitbang.h b/include/linux/mdio-bitbang.h
> index a6e6057886..49fe435429 100644
> --- a/include/linux/mdio-bitbang.h
> +++ b/include/linux/mdio-bitbang.h
> @@ -36,6 +36,9 @@ struct mdiobb_ctrl {
>  	const struct mdiobb_ops *ops;
>  	/* reset callback */
>  	int (*reset)(struct mii_bus *bus);
> +	unsigned int override_op_c22;
> +	u8 op_c22_read;
> +	u8 op_c22_write;
>  };
>  
>  /* The returned bus is not yet registered with the phy layer. */
> -- 
> 2.30.2
> 
> 
> 

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