net: phy: Allow splitting MDIO bus/device support from PHYs

Introduce a new configuration symbol: MDIO_DEVICE which allows building
the MDIO devices and bus code, without pulling in the entire Ethernet
PHY library and devices code.

PHYLIB nows select MDIO_DEVICE and the relevant Makefile files are
updated to reflect that.

When MDIO_DEVICE (MDIO bus/device only) is selected, but not PHYLIB, we
have mdio-bus.ko as a loadable module, and it does not have a
module_exit() function because the safety of removing a bus class is
unclear.

When both MDIO_DEVICE and PHYLIB are enabled, we need to assemble
everything into a common loadable module: libphy.ko because of nasty
circular dependencies between phy.c, phy_device.c and mdio_bus.c which
are really tough to untangle.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 82d915614646..0e1ec0438c23 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -1,7 +1,16 @@
 # Makefile for Linux PHY drivers and MDIO bus drivers
 
-libphy-y			:= phy.o phy_device.o mdio_bus.o mdio_device.o \
-				   mdio-boardinfo.o phy-core.o
+libphy-y			:= phy.o phy-core.o phy_device.o
+mdio-bus-y			+= mdio_bus.o mdio_device.o mdio-boardinfo.o
+
+# PHYLIB implies MDIO_DEVICE, in that case, we have a bunch of circular
+# dependencies that does not make it possible to split mdio-bus objects into a
+# dedicated loadable module, so we bundle them all together into libphy.ko
+ifdef CONFIG_PHYLIB
+libphy-y			+= $(mdio-bus-y)
+else
+obj-$(CONFIG_MDIO_DEVICE)	+= mdio-bus.o
+endif
 libphy-$(CONFIG_SWPHY)		+= swphy.o
 libphy-$(CONFIG_LED_TRIGGER_PHY)	+= phy_led_triggers.o