| .. SPDX-License-Identifier: GPL-2.0-or-later |
| .. Luigi 'Comio' Mantellini <luigi.mantellini@idf-hit.com>, Industrie Dial Face S.p.A., 2009 |
| |
| Bit-banged MII bus support |
| ========================== |
| |
| The miiphybb ( Bit-banged MII bus driver ) supports an arbitrary number of |
| MII buses. This feature is useful when a driver uses different MII buses for |
| different PHYs and all (or a part) of these buses are implemented via |
| bit-banging mode. |
| |
| The driver requires that the following macro is defined in the board |
| configuration file: |
| |
| * CONFIG_BITBANGMII - Enable the miiphybb driver |
| |
| The driver code needs to allocate a regular MDIO device using mdio_alloc() |
| and assign .read and .write accessors which wrap bb_miiphy_read() and |
| bb_miiphy_write() functions respectively. The bb_miiphy_read() and |
| bb_miiphy_write() functions take a pointer to a callback structure, |
| struct bb_miiphy_bus_ops. The struct bb_miiphy_bus_ops has the following |
| fields/callbacks (see miiphy.h for details): |
| |
| .. code-block:: c |
| |
| int (*mdio_active)() // Activate the MDIO pin as output |
| int (*mdio_tristate)() // Activate the MDIO pin as input/tristate pin |
| int (*set_mdio)() // Write the MDIO pin |
| int (*get_mdio)() // Read the MDIO pin |
| int (*set_mdc)() // Write the MDC pin |
| int (*delay)() // Delay function |
| |
| The driver code will look like: |
| |
| .. code-block:: c |
| |
| static const struct bb_miiphy_bus_ops ravb_bb_miiphy_bus_ops = { |
| .mdio_active = ravb_bb_mdio_active, |
| .mdio_tristate = ravb_bb_mdio_tristate, |
| .set_mdio = ravb_bb_set_mdio, |
| .get_mdio = ravb_bb_get_mdio, |
| .set_mdc = ravb_bb_set_mdc, |
| .delay = ravb_bb_delay, |
| }; |
| |
| static int ravb_bb_miiphy_read(struct mii_dev *miidev, int addr, |
| int devad, int reg) |
| { |
| return bb_miiphy_read(miidev, &ravb_bb_miiphy_bus_ops, |
| addr, devad, reg); |
| } |
| |
| static int ravb_bb_miiphy_write(struct mii_dev *miidev, int addr, |
| int devad, int reg, u16 value) |
| { |
| return bb_miiphy_write(miidev, &ravb_bb_miiphy_bus_ops, |
| addr, devad, reg, value); |
| } |
| |
| static int ravb_probe(struct udevice *dev) |
| { |
| struct mii_dev *mdiodev; |
| ... |
| mdiodev = mdio_alloc(); |
| if (!mdiodev) |
| return -ENOMEM; |
| |
| mdiodev->read = ravb_bb_miiphy_read; |
| mdiodev->write = ravb_bb_miiphy_write; |
| mdiodev->priv = eth; |
| snprintf(mdiodev->name, sizeof(mdiodev->name), dev->name); |
| |
| ret = mdio_register(mdiodev); |
| ... |
| } |