On Wed, Feb 20, 2002 at 06:48:50PM -0800, Matthew Dharm wrote:
> But isn't that what all the complicated logic in ioremap() is for?
Not exactly.
Here is the whole picture:
drivers do inb(delta)/outb(delta)
-> translated to an virtual address (mips_io_port_base + delta)
-> mapped into (GT_IO_BASE + delta) physical addr
-> Bingo! you got the devices.
Here your goal is to make the drivers that do inb()/outb() happy (i.e.,
be able to reuse them without modification) If you only use drivers
that directly access memory (such as drivers/net/nec_korva.c on
linux-mips.sf.net), then you don't even have to set mips_io_port_base at all.
The ioremap() comes into place because by default you can not
set a mips_io_port_base value in kseg1 range on ocelot (it is at 0x20000000
in physical addr space). Therefore you do a ioremap(), blah blah as explained
above.
Someday I should finish the PCI chapter on my porting guide ...
Jun
