quoted

2. Single DT_MACHINE_START matching (the most generic) "arm,vexpress"
and doing (rougly) this in v2m_map_io:

of_scan_flat_dt(v2m_dt_iotable_init, NULL);

v2m_dt_iotable_init(...)
{
	if (depth != 0)
		return 0;
	if (of_flat_dt_is_compatible(node, "arm,vexpress-legacy"))
		iotable_init(v2m_io_desc_legacy);
	else (of_flat_dt_is_compatible(node, "arm,vexpress-rs1"))
		iotable_init(v2m_io_desc_rs1);
	else
		panic();
}

Neither of them seem particularly appealing... ;-)

But I think both ways would be acceptable in the end. It's not a lot
of extra code either way. In the second case, I would probably have
the legacy case as a special variant of the map_io function and have
all others be the default instead of falling back to panic though.

Ok, I'll go (roughly) that way.

quoted

In my case it's sysreg and sysctl. There are two more users of static
mappings: timer01 and timer23, but they could at some point do ioremap()
on their own (especially with Nico's changes).

Well, I think with Nico's cahnges, you /can/ actually do ioremap for
areas that have been mapped through the iotable before kmalloc is up.
IIRC, omap does this for a number of peripherals.

It's a bit of a hack, but I think it's much better than taking hardcoded
addresses.

Yes, I was thinking about that last night. If you think it's acceptable
I'll do this (killing MMIO_P2V on the way ;-)

With the combination of the points mentioned above, you should be
able to do:

- map the entire I/O area in map_io(), depending on the board
- have an __iomem pointer for the sysreg
- populate that pointer using of_iomap from the device tree address
  before you first access it.

Do you think that would work?

Yes, I suppose so. The last bit (getting the offset from DT) will be a
little ugly, I think, but let's wait till I get some code done.

Cheers!

Paweł



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