An integrated multiplexer uses same address space for
"muxed bus selection" and "generation of mdio transaction"
hence its good to register parent bus from mux driver.
Hence added a mechanism where mux driver could register a
parent bus and pass it down to framework via mdio_mux_init api.
Signed-off-by: Pramod Kumar <pramod.kumar@broadcom.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds a somewhat generic framework for MDIO bus
multiplexers. It is modeled on the I2C multiplexer.
The multiplexer is needed if there are multiple PHYs with the same
address connected to the same MDIO bus adepter, or if there is
insufficient electrical drive capability for all the connected PHY
devices.
Conceptually it could look something like this:
------------------
| Control Signal |
--------+---------
|
--------------- --------+------
| MDIO MASTER |---| Multiplexer |
--------------- --+-------+----
| |
C C
h h
i i
l l
d d
| |
--------- A B ---------
| | | | | |
| PHY@1 +-------+ +---+ PHY@1 |
| | | | | |
--------- | | ---------
--------- | | ---------
| | | | | |
| PHY@2 +-------+ +---+ PHY@2 |
| | | |
--------- ---------
This framework configures the bus topology from device tree data. The
mechanics of switching the multiplexer is left to device specific
drivers.
The follow-on patch contains a multiplexer driven by GPIO lines.
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
