uboot/u-boot-stm32mp-2020.01/doc/README.bitbangMII

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This patch rewrites the miiphybb ( Bit-banged MII bus driver ) in order to
support an arbitrary number of mii buses. This feature is useful when your
board 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 macros should be defined into the board
configuration file:
CONFIG_BITBANGMII - Enable the miiphybb driver
CONFIG_BITBANGMII_MULTI - Enable the multi bus support
If the CONFIG_BITBANGMII_MULTI is not defined, the board's config file needs
to define at least the following macros:
MII_INIT - Generic code to enable the MII bus (optional)
MDIO_DECLARE - Declaration needed to access to the MDIO pin (optional)
MDIO_ACTIVE - Activate the MDIO pin as out pin
MDIO_TRISTATE - Activate the MDIO pin as input/tristate pin
MDIO_READ - Read the MDIO pin
MDIO(v) - Write v on the MDIO pin
MDC_DECLARE - Declaration needed to access to the MDC pin (optional)
MDC(v) - Write v on the MDC pin
The previous macros make the driver compatible with the previous version
(that didn't support the multi-bus).
When the CONFIG_BITBANGMII_MULTI is also defined, the board code needs to fill
the bb_miiphy_buses[] array with a record for each required bus and declare
the bb_miiphy_buses_num variable with the number of mii buses.
The record (struct bb_miiphy_bus) has the following fields/callbacks (see
miiphy.h for details):
char name[] - The symbolic name that must be equal to the MII bus
registered name
int (*init)() - Initialization function called at startup time (just
before the Ethernet initialization)
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
void *priv - Private data used by board specific code
The board code will look like:
struct bb_miiphy_bus bb_miiphy_buses[] = {
{ .name = "miibus#1", .init = b1_init, .mdio_active = b1_mdio_active, ... },
{ .name = "miibus#2", .init = b2_init, .mdio_active = b2_mdio_active, ... },
...
};
int bb_miiphy_buses_num = sizeof(bb_miiphy_buses) /
sizeof(bb_miiphy_buses[0]);
2009 Industrie Dial Face S.p.A.
Luigi 'Comio' Mantellini <luigi.mantellini@idf-hit.com>