I finally got it working, its not fully supported by openwrt as of yet. The tg3 driver actually covers quite a few different devices. If you go to their website you will see card specific drivers so having a generic name is quite silly thanks broadcom!! and confuses the linux comunity. So depending which driver has been officially compiled is the one that will be offered to everyone. The catch with the TG3 driver for the openwrt community and other smaller devices is the driver from broadcom has actually to be cross compiled on the device. and the make file then creates a custom image for your device. I have managed to crosscompile the driver but as it wasnt from my router, so fails to load on boot up. With a few small mods in the bootup sequence it loads up and runs quite fast.
[ 2.595952] tg3.c:v3.132 (May 21, 2013)
[ 2.601053] libphy: tg3 mdio bus: probed
[ 2.604804] tg3 0000:05:00.0: No PHY devices
[ 2.608668] tg3 0000:05:00.0: Problem fetching invariants of chip, aborting
Then during the bootup period it switches to my driver
pcieport 0000:00:1c.5: eth2: Tigon3 [partno(BCM57780) rev 778000 1] (PCI Express) MAC address 3c:4axxxxx
pcieport 0000:00:1c.5: eth2: attached PHY is 57780 (10/100/1000Base-T Ethernet) (WireSpeed[1], EEE[0])
pcieport 0000:00:1c.5: eth2: RXcsums[1] LinkChgREG[0] MIirq[0] AS F[0] TSOcap[1]
pcieport 0000:00:1c.5: eth2: dma_rwctrl[76180000] dma_mask[64-bit
lspci
05:00.0 Ethernet controller [0200]: Broadcom Corporation NetLink BCM57780 Gigabit Ethernet PCIe [14e4:1692] (rev 01)
Subsystem: Broadcom Corporation Device [14e4:9692]
Flags: bus master, fast devsel, latency 0, IRQ 17
Memory at febf0000 (64-bit, non-prefetchable) [size=64K]
Capabilities: [48] Power Management version 3
Capabilities: [60] Vendor Specific Information: Len=6c <?>
Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
Capabilities: [cc] Express Endpoint, MSI 00
Capabilities: [100] Advanced Error Reporting
Capabilities: [13c] Virtual Channel
Capabilities: [160] Device Serial Number 3c-4a-92-ff-fe-d3-f7-d0
Capabilities: [16c] Power Budgeting <?>
Kernel driver in use: tg3