This Patch adds support to the asix.ko driver for the AX88772C in
Reverse-RMII mode.

 

The 'asix.ko' driver is designed to support 88772A, B and C.

The AX88772C supports running in Reverse-RMII mode to enable MAC to MAC
communication.

The base 'asix.ko' driver does NOT currently support the AX88772C in
Reverse-RMII mode.

 

This is due to several reasons:

1.	The AX88772C PHY register "LINK STATUS" Link value never is set to
1. 

a.	This prevents the drivers from setting the interface 'UP'

2.	The AX88772C PHY-ID is hard coded to 0x10, this configures the chip
to use the internal PHY not an external PHY.

a.	To use the AX88772C in Reverse-RMII mode, the chip must be
configured to use the external 'PHY'.

 

Asix provides a dedicated AX88772C driver which supports Reverse-RMII. This
'C' driver was references to add Reverse-RMII support to the base asix.ko
driver.

To resolve the issue, the following changes were made:

1.	MDIO_READ prior to configuring chip to determine what operational
mode it is in (Internal, RMII, or Reverse-RMII)
2.	If in Reverse-RMII mode, force chip to be configured as if it had an
external PHY.
3.	If in Reverse-RMII mode, set the interface status to UP regardless
of the value of the 'LINK STATUS' bit.