[RFC PATCH 1/3] of: provide a binding for the 'fixed-link' property

[Grant Likely]

On Mon, Jul 15, 2013 at 4:34 PM, Thomas Petazzoni
<thomas.petazzoni at free-electrons.com> wrote:
> Some Ethernet MACs have a "fixed link", and are not connected to a
> normal MDIO-managed PHY device. For those situations, a Device Tree
> binding allows to describe a "fixed link", as a "fixed-link" property
> of the Ethernet device Device Tree node.
>
> This patch adds:
>
>  * A documentation for the Device Tree property "fixed-link".
>
>  * A of_phy_register_fixed_link() OF helper, which provided an OF node
>    that contains a "fixed-link" property, registers the corresponding
>    fixed PHY.
>
>  * Removes the warning on the of_phy_connect_fixed_link() that says
>    new drivers should not use it, since Grant Likely indicated that
>    this "fixed-link" property is indeed the way to go.
>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> ---
>  .../devicetree/bindings/net/fixed-link.txt         | 26 ++++++++++++++++
>  drivers/of/of_mdio.c                               | 36 +++++++++++++++++++---
>  include/linux/of_mdio.h                            | 10 ++++++
>  3 files changed, 68 insertions(+), 4 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/net/fixed-link.txt
>
> diff --git a/Documentation/devicetree/bindings/net/fixed-link.txt b/Documentation/devicetree/bindings/net/fixed-link.txt
> new file mode 100644
> index 0000000..25a009a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/fixed-link.txt
> @@ -0,0 +1,26 @@
> +Fixed link Device Tree binding
> +------------------------------
> +
> +Some Ethernet MACs have a "fixed link", and are not connected to a
> +normal MDIO-managed PHY device. For those situations, a Device Tree
> +binding allows to describe a "fixed link".
> +
> +Such a fixed link situation is described within an Ethernet device
> +Device Tree node using a 'fixed-link' property, composed of 5
> +elements:
> +
> + 1. A fake PHY ID, which must be unique accross all fixed-link PHYs in
> +    the system.

That's just loony!  :)  Regardless of existing code doing this, it is
absolutely ridiculous to have it in the driver. The kernel should
handle generating a phy id transparently. I'd rather mark this field
as reserved in the binding and change the code to not care about it
anymore.

g.

> + 2. The duplex (1 for full-duplex, 0 for half-duplex)
> + 3. The speed (10, 100, 1000)
> + 4. The pause setting (1 for enabled, 0 for disabled)
> + 5. The asym pause setting (1 for enabled, 0 for disabled)
> +
> +Example:
> +
> +ethernet at 0 {
> +       ...
> +       fixed-link = <1 1 1000 0 0>;
> +       ...
> +};
> +
> diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
> index d5a57a9..66d5591 100644
> --- a/drivers/of/of_mdio.c
> +++ b/drivers/of/of_mdio.c
> @@ -14,6 +14,7 @@
>  #include <linux/netdevice.h>
>  #include <linux/err.h>
>  #include <linux/phy.h>
> +#include <linux/phy_fixed.h>
>  #include <linux/of.h>
>  #include <linux/of_irq.h>
>  #include <linux/of_mdio.h>
> @@ -215,10 +216,6 @@ EXPORT_SYMBOL(of_phy_connect);
>   * @dev: pointer to net_device claiming the phy
>   * @hndlr: Link state callback for the network device
>   * @iface: PHY data interface type
> - *
> - * This function is a temporary stop-gap and will be removed soon.  It is
> - * only to support the fs_enet, ucc_geth and gianfar Ethernet drivers.  Do
> - * not call this function from new drivers.
>   */
>  struct phy_device *of_phy_connect_fixed_link(struct net_device *dev,
>                                              void (*hndlr)(struct net_device *),
> @@ -247,3 +244,34 @@ struct phy_device *of_phy_connect_fixed_link(struct net_device *dev,
>         return IS_ERR(phy) ? NULL : phy;
>  }
>  EXPORT_SYMBOL(of_phy_connect_fixed_link);
> +
> +#if defined(CONFIG_FIXED_PHY)
> +/**
> + * of_phy_register_fixed_link - Parse fixed-link property and register a dummy phy
> + * @np: pointer to the OF device node that contains the "fixed-link"
> + * property for which a dummy phy should be registered.
> + */
> +#define FIXED_LINK_PROPERTIES_COUNT 5
> +int of_phy_register_fixed_link(struct device_node *np)
> +{
> +       struct fixed_phy_status status = {};
> +       u32 fixed_link_props[FIXED_LINK_PROPERTIES_COUNT];
> +       int ret;
> +
> +       ret = of_property_read_u32_array(np, "fixed-link",
> +                                        fixed_link_props,
> +                                        FIXED_LINK_PROPERTIES_COUNT);
> +       if (ret < 0)
> +               return ret;
> +
> +       status.link       = 1;
> +       status.duplex     = fixed_link_props[1];
> +       status.speed      = fixed_link_props[2];
> +       status.pause      = fixed_link_props[3];
> +       status.asym_pause = fixed_link_props[4];
> +
> +       return fixed_phy_add(PHY_POLL, fixed_link_props[0],
> +                            &status);
> +}
> +EXPORT_SYMBOL(of_phy_register_fixed_link);
> +#endif
> diff --git a/include/linux/of_mdio.h b/include/linux/of_mdio.h
> index 8163107..bf6efea 100644
> --- a/include/linux/of_mdio.h
> +++ b/include/linux/of_mdio.h
> @@ -57,4 +57,14 @@ static inline struct mii_bus *of_mdio_find_bus(struct device_node *mdio_np)
>  }
>  #endif /* CONFIG_OF */
>
> +#if defined(CONFIG_OF) && defined(CONFIG_FIXED_PHY)
> +extern int of_phy_register_fixed_link(struct device_node *np);
> +#else
> +static inline int of_phy_register_fixed_link(struct device_node *np)
> +{
> +       return -ENOSYS;
> +}
> +#endif
> +
> +
>  #endif /* __LINUX_OF_MDIO_H */
> --
> 1.8.1.2
>