net: phy: add Broadcom BCM54140 support

The Broadcom BCM54140 is a Quad SGMII/QSGMII Copper/Fiber Gigabit
Ethernet transceiver.

This also adds support for tunables to set and get downshift and
energy detect auto power-down.

The PHY has four ports and each port has its own PHY address.
There are per-port registers as well as global registers.
Unfortunately, the global registers can only be accessed by reading
and writing from/to the PHY address of the first port. Further,
there is no way to find out what port you actually are by just
reading the per-port registers. We therefore, have to scan the
bus on the PHY probe to determine the port and thus what address
we need to access the global registers.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/Kconfig

@@ -346,6 +346,16 @@ config BROADCOM_PHY
 	  Currently supports the BCM5411, BCM5421, BCM5461, BCM54616S, BCM5464,
 	  BCM5481, BCM54810 and BCM5482 PHYs.
 
+config BCM54140_PHY
+	tristate "Broadcom BCM54140 PHY"
+	depends on PHYLIB
+	select BCM_NET_PHYLIB
+	help
+	  Support the Broadcom BCM54140 Quad SGMII/QSGMII PHY.
+
+	  This driver also supports the hardware monitoring of this PHY and
+	  exposes voltage and temperature sensors.
+
 config BCM84881_PHY
 	tristate "Broadcom BCM84881 PHY"
 	depends on PHYLIB

drivers/net/phy/Makefile

@@ -68,6 +68,7 @@ obj-$(CONFIG_BCM87XX_PHY)	+= bcm87xx.o
 obj-$(CONFIG_BCM_CYGNUS_PHY)	+= bcm-cygnus.o
 obj-$(CONFIG_BCM_NET_PHYLIB)	+= bcm-phy-lib.o
 obj-$(CONFIG_BROADCOM_PHY)	+= broadcom.o
+obj-$(CONFIG_BCM54140_PHY)	+= bcm54140.o
 obj-$(CONFIG_BCM84881_PHY)	+= bcm84881.o
 obj-$(CONFIG_CICADA_PHY)	+= cicada.o
 obj-$(CONFIG_CORTINA_PHY)	+= cortina.o