Now that all of the on-chip switch and basic platform support is updated,

we can now add all the hardware bits for the DB120.

* arge0/argemdio0 is hooked up to an AR8327 switch - which there's currently
  no support for.  However, the bootloader on this board does set it up as
  a basic switch so we can at least _use_ it ourselves.

  So we should at least configure the arge0 side of things, including the GMAC
  register.

* .. the GMAC config peels off arge0 from the internal switch and exposes it
  as an RGMII to said AR8327.

* arge1/argemdio1 are hooked up to an internal 10/100 switch.  So, that also
  needs configuring.

* Add support for the NOR flash layout.

* Add support for the wifi (which works, with bugs, but it works.)

What's missing!

* No GPIO stuff yet!
* No sound (I2S) and no NAND flash support yet, sorry!
* The normal DB120 has an external AR95xx wifi chip on PCIe but with the
  actual calibration data in the NOR flash.  My DB120 has been modified
  to let me use the PCIe slot as a normal PCIe slot.  I'll add the "default"
  settings later when I have access to a non-modified one.
* Other stuff, like why the wifi unit gets upset and spits out stuck beacons
  and interrupt storms everywhere.  Sigh.

Tested:

* DB120 board - AR9344 (mips74k SoC) booting off of SPI flash into multi-user
  mode.

sys/mips/conf/DB120.hints

@@ -1,3 +1,104 @@
 # $FreeBSD$
 
 # This is a placeholder until the hardware support is complete.
+
+# mdiobus0 on arge0
+hint.argemdio.0.at="nexus0"
+hint.argemdio.0.maddr=0x19000000
+hint.argemdio.0.msize=0x1000
+hint.argemdio.0.order=0
+
+# DB120 GMAC configuration
+# + AR934X_ETH_CFG_RGMII_GMAC0              (1 << 0)
+# + AR934X_ETH_CFG_SW_ONLY_MODE             (1 << 6)
+hint.ar934x_gmac.0.gmac_cfg=0x41
+
+# GMAC0 here - connected to an AR8327
+#hint.arswitch.0.at="mdio0"
+#hint.arswitch.0.is_7240=0
+#hint.arswitch.0.is_9340=0	# not the internal switch!
+#hint.arswitch.0.numphys=5
+#hint.arswitch.0.phy4cpu=0
+#hint.arswitch.0.is_rgmii=1
+#hint.arswitch.0.is_gmii=0
+
+# XXX OpenWRT DB120 BSP doesn't have media/duplex set?
+hint.arge.0.phymask=0x0
+hint.arge.0.media=1000
+hint.arge.0.fduplex=1
+hint.arge.0.miimode=3           # RGMII
+hint.arge.0.pll_1000=0x06000000
+
+# mdiobus1 on arge1
+hint.argemdio.1.at="nexus0"
+hint.argemdio.1.maddr=0x1a000000
+hint.argemdio.1.msize=0x1000
+hint.argemdio.1.order=0
+
+# Embedded switch on the AR9344
+hint.arswitch.1.at="mdio1"
+hint.arswitch.1.is_7240=0
+hint.arswitch.1.is_9340=1
+hint.arswitch.1.numphys=4
+hint.arswitch.1.phy4cpu=0       # phy 4 is not a "CPU port" PHY here
+hint.arswitch.1.is_rgmii=0
+hint.arswitch.1.is_gmii=1       # arge1 <-> switch PHY is GMII
+
+# arge1 - lock up to 1000/full
+hint.arge.1.phymask=0x0		# Nothing attached here (XXX?)
+hint.arge.1.media=1000
+hint.arge.1.fduplex=1
+hint.arge.1.miimode=1		# GMII
+
+# flash layout:
+#
+# bootargs=console=ttyS0,115200 root=31:02 rootfstype=jffs2 init=/sbin/init mtdparts=ath-nor0:256k(u-boot),64k(u-boot-env),6336k(rootfs),1408k(uImage),64k(mib0),64k(ART)
+
+# 256KiB u-boot
+hint.map.0.at="flash/spi0"
+hint.map.0.start=0x00000000
+hint.map.0.end=0x00040000	# 256k u-boot
+hint.map.0.name="u-boot"
+hint.map.0.readonly=1
+
+# 64KiB u-boot-env
+hint.map.1.at="flash/spi0"
+hint.map.1.start=0x00040000
+hint.map.1.end=0x00050000	# 64k u-boot-env
+hint.map.1.name="u-boot-env"
+hint.map.1.readonly=1
+
+# 6336KiB rootfs
+hint.map.2.at="flash/spi0"
+hint.map.2.start=0x00050000
+hint.map.2.end=0x00680000	# 6336k rootfs
+hint.map.2.name="rootfs"
+hint.map.2.readonly=1
+
+# 1344KiB uImage
+hint.map.3.at="flash/spi0"
+hint.map.3.start=0x00680000
+hint.map.3.end=0x007d0000	# 1408k uImage, 64k off the end..
+hint.map.3.name="uImage"
+hint.map.3.readonly=1
+
+# 64KiB cfg
+hint.map.4.at="flash/spi0"
+hint.map.4.start=0x007d0000
+hint.map.4.end=0x007e0000
+hint.map.4.name="cfg"
+hint.map.4.readonly=0
+
+# 64KiB mib0
+hint.map.5.at="flash/spi0"
+hint.map.5.start=0x007e0000
+hint.map.5.end=0x007f0000	# 64k mib0
+hint.map.5.name="mib0"
+hint.map.5.readonly=1
+
+# 64KiB ART
+hint.map.6.at="flash/spi0"
+hint.map.6.start=0x007f0000
+hint.map.6.end=0x00800000	# 64k ART
+hint.map.6.name="ART"
+hint.map.6.readonly=1