netdev/phy: add MDIO bus multiplexer driven by a memory-mapped device

Add support for an MDIO bus multiplexer controlled by a simple memory-mapped
device, like an FPGA.  The device must be memory-mapped and contain only
8-bit registers (which keeps things simple).

Tested on a Freescale P5020DS board which uses the "PIXIS" FPGA attached
to the localbus.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 3090dc65a6f1..983bbf4d5ef6 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -159,6 +159,19 @@ config MDIO_BUS_MUX_GPIO
           several child MDIO busses to a parent bus.  Child bus
           selection is under the control of GPIO lines.
 
+config MDIO_BUS_MUX_MMIOREG
+        tristate "Support for MMIO device-controlled MDIO bus multiplexers"
+        depends on OF_MDIO
+        select MDIO_BUS_MUX
+        help
+          This module provides a driver for MDIO bus multiplexers that
+          are controlled via a simple memory-mapped device, like an FPGA.
+          The multiplexer connects one of several child MDIO busses to a
+          parent bus.  Child bus selection is under the control of one of
+          the FPGA's registers.
+
+          Currently, only 8-bit registers are supported.
+
 endif # PHYLIB
 
 config MICREL_KS8995MA