RE: [PATCH v2 1/2] sparc: explicitly set PCI_IOBASE to 0

[David Laight]

From: Niklas Schnelle
> Sent: 15 April 2021 13:37
> 
> Instead of relying on the fallback in asm-generic/io.h which sets
> PCI_IOBASE 0 if it is not defined set it explicitly.
> 
> Link: https://lore.kernel.org/lkml/CAK8P3a3PK9zyeP4ymELtc2ZYnymECoACiigw9Za+pvSJpCk5=g@xxxxxxxxxxxxxx/
> Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
> ---
>  arch/sparc/include/asm/io.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/sparc/include/asm/io.h b/arch/sparc/include/asm/io.h
> index 2eefa526b38f..100992ba1317 100644
> --- a/arch/sparc/include/asm/io.h
> +++ b/arch/sparc/include/asm/io.h
> @@ -1,6 +1,10 @@
>  /* SPDX-License-Identifier: GPL-2.0 */
>  #ifndef ___ASM_SPARC_IO_H
>  #define ___ASM_SPARC_IO_H
> +
> +/* On LEON I/O Space is accessed through low iomem */
> +#define PCI_IOBASE ((void __iomem *)0)
> +
>  #if defined(__sparc__) && defined(__arch64__)
>  #include <asm/io_64.h>
>  #else
> --
> 2.25.1

Not sure the comment is informative enough.
Maybe something like:

/*
 * On LEON PCI addresses below 64k are converted to IO accesses.
 * io_remap_xxx() (whatever is it called) returns a kernel virtual
 * address in the PCI window so inb() doesn't need to add an offset.
 */

That'll save the next person doing a lot of digging.

	David

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