Cerfcube 405EP

This is the basis of a port to a range of IBM PowerPC 405 devices.
At some point all the common code will move to ../ppc, as is done
for SA1110, MPC8xx, and others.

Currently untested:
	- both EMAC0 and EMAC1 are initialised, but EMAC1 hasn't been tested (i need to get a cable made);
	  the PHY for it is detected and initialised, so i think it should work
	- pci has not been tested since i haven't yet got the mini-PCI card i need

Will change:
	- devuart.c/uart.h will be replaced by ../port/devuart.c and uart405.c eventually
	- power control will be extended

mk in this directory should produce a file `icerfhd', which is icerf parcelled as ppcboot/uboot expects it.
put it where your tftp server can find it.

on the machine to be used as file server, run inferno and start svc/net
to serve Styx

To boot Inferno:
	1. set up a dhcp/tftp server for the EMAC0 MAC address, referring to the icerfhd file as the bootfile.
	2. connect a b115200 l8 pn serial port to talk to the ppcboot/uboot bootstrap
	3. reset the 405, and interrupt the automatic boot to get to the bootstrap's prompt
	4. type
		bootp
	5. if dhcp is set correctly, that should load the Inferno boot image into memory at 0x300000
	6. type
		bootm
	    to boot that image.

To put Inferno kernel image (icerfhd) on NAND flash:
	- the boot area is 0 to 0x100000 on NAND (perhaps a bit more, but 0x100000 is currently fine)
	1. get to the bootstrap's prompt.
	2. nand erase 0 0x100000
	3. bootp		# loads the image to 0x300000 by tftp
	4. nand write 0x300000 0 0x100000
	5. a subsequent {nand; bootm} (as for auto boot) should run that kernel.

To initialise a file system on the NAND flash:
	1. set logfsformat=yes in the environment
	2. boot inferno
	3. choose remote file system or kernel file system when offered
	4. the empty flash file system should be in /n/local
