NOTES

IO is the interface for read and write.

It is implemented as a p9, direct file, or direct memory write.

So we need to connect reg to IO and we should be there.

see t9/reg.go: that part is done.

This needs /dev/reg32, and that is implemented as well.

So for LED, what remains, is to read and write the reg32, and set the bit.

reg32_tamago.go has the blue and white. What is missing so far is the
register offset for read/write

	usbarmory.LED(arg[0], on) should be where we find it.
	also see func (f reg32File) Pread(b []byte, offset int64) (int, error) {

the reg32File has no file yet. Seems it needs to have an IO? But for now, Pread
can just do the open, read, close.

The basic path

at top level, in init, we make files e.g. /dev/white

at top level, we open those files

we do IO on those files. the *file is provided by the os.OpenFile. It is passed in. This will give us access to the private date, provided
by the function that was used in MkDev.

OH HO. In the led driver, we should open /dev/reg32, duh.


t9/reg.go is the t9 version of reg32_tamago.go

OK
the drivers don't call syscall.mkdev
rather, at init, they register a function:
func Creator(func() FS) error
once the startup has created the FS, it calls this function, which in turn will register the drivers, so they have a function to call to get the current FS.