Scott Wood wrote:

Previously, bitbanged MDIO was only supported in individual
hardware-specific drivers.  This code factors out the higher level
protocol implementation, reducing the hardware-specific portion to
functions setting direction, data, and clock.

Signed-off-by: Scott Wood <redacted>
---
 drivers/net/phy/Kconfig        |    9 ++
 drivers/net/phy/Makefile       |    1 +
 drivers/net/phy/mdio-bitbang.c |  187 ++++++++++++++++++++++++++++++++++++++++
 include/linux/mdio-bitbang.h   |   42 +++++++++
 4 files changed, 239 insertions(+), 0 deletions(-)
 create mode 100644 drivers/net/phy/mdio-bitbang.c
 create mode 100644 include/linux/mdio-bitbang.h

I cannot ACK this, nor do I want to see it merged, until users appear 
and have been reviewed alongside this.  I do not see any fs_enet patches 
that actually use this.

five-second-glance comments:

* "mdio_bitbang_" is a long prefix.  consider "mdiobb_" or somesuch

* the delay (where you call ndelay()) is not guaranteed without a flush 
of some sort

* how widely applicable is this "generic" library?  have you converted 
any non-embedded drivers over to it?