On Thursday, November 10, 2016 3:36:49 PM CET Gabriele Paoloni wrote:
>
> Where should we get the range from? For LPC we know that it is going
> Work on anything that is not used by PCI I/O space, and this is
> why we use [0, PCIBIOS_MIN_IO]
It should be allocated the same way we allocate PCI config space
segments. This is currently done with the io_range list in
drivers/pci/pci.c, which isn't perfect but could be extended
if necessary. Based on what others commented here, I'd rather
make the differences between ISA/LPC and PCI I/O ranges smaller
than larger.
> > Your current version has
> >
> > if (arm64_extio_ops->pfout) \
> > arm64_extio_ops->pfout(arm64_extio_ops->devpara,\
> > addr, value, sizeof(type)); \
> >
> > Instead, just subtract the start of the range from the logical
> > port number to transform it back into a bus-local port number:
>
> These accessors do not operate on IO tokens:
>
> If (arm64_extio_ops->start > addr || arm64_extio_ops->end < addr)
> addr is not going to be an I/O token; in fact patch 2/3 imposes that
> the I/O tokens will start at PCIBIOS_MIN_IO. So from 0 to PCIBIOS_MIN_IO
> we have free physical addresses that the accessors can operate on.
Ah, I missed that part. I'd rather not use PCIBIOS_MIN_IO to refer to
the logical I/O tokens, the purpose of that macro is really meant
for allocating PCI I/O port numbers within the address space of
one bus.
Note that it's equally likely that whichever next platform needs
non-mapped I/O access like this actually needs them for PCI I/O space,
and that will use it on addresses registered to a PCI host bridge.
If we separate the two steps:
a) assign a range of logical I/O port numbers to a bus
b) register a set of helpers for redirecting logical I/O
port to a helper function
then I think the code will get cleaner and more flexible.
It should actually then be able to replace the powerpc
specific implementation.
Arnd
