Re: isa_read/write not available on ppc - solution suggestions ??

Linus Torvalds (torvalds@transmeta.com)
Tue, 1 May 2001 15:46:22 -0700 (PDT)


On Tue, 1 May 2001, Russell King wrote:
>
> In which case, can we change the following in IO-mapping.txt please?

Oh, sorry. I misread your question. The _return_ value is a cookie.

The first argument should basically be the start of a "struct pci_dev"
resource entry, but obviously architecture-specific code can (and does)
know what the thing means. And the ISA space (ie 0xA0000-0x100000) has
been considered an acceptable special case.

So the only usage that is "portable" is to do something like

cookie = ioremap(pdev->resource[0].start, pdev->resource[0].len);

and I guess we should actually create some helper functions for that too.

You can use ioremap in other ways, but there's nothing to say that they
will work reliably across multiple PCI buses etc.

Linus

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