linux-kernel - Re: [PATCH v2 1/4] arch/*/asm/io.h: add ioremap

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Date:	Mon, 01 Jun 2015 16:36:06 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	arnd@...db.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
	tglx@...utronix.de, ross.zwisler@...ux.intel.com,
	akpm@...ux-foundation.org, jgross@...e.com, x86@...nel.org,
	linux-nvdimm@...ts.01.org, mcgrof@...e.com, konrad.wilk@...cle.com,
	linux-kernel@...r.kernel.org, stefan.bader@...onical.com,
	luto@...capital.net, linux-mm@...ck.org, geert@...ux-m68k.org,
	hmh@....eng.br, tj@...nel.org, hch@....de
Subject: Re: [PATCH v2 1/4] arch/*/asm/io.h: add ioremap_cache() to all
 architectures

On Sat, 2015-05-30 at 14:59 -0400, Dan Williams wrote:
> Similar to ioremap_wc() let architecture implementations optionally
> provide ioremap_cache().  As is, current ioremap_cache() users have
> architecture dependencies that prevent them from compiling on archs
> without ioremap_cache().  In some cases the architectures that have a
> cached ioremap() capability have an identifier other than
> "ioremap_cache".
> 
> Allow drivers to compile with ioremap_cache() support and fallback to a
> safe / uncached ioremap otherwise.
 :
> diff --git a/arch/mn10300/include/asm/io.h b/arch/mn10300/include/asm/io.h
> index 07c5b4a3903b..dcab414f40df 100644
> --- a/arch/mn10300/include/asm/io.h
> +++ b/arch/mn10300/include/asm/io.h
> @@ -283,6 +283,7 @@ static inline void __iomem *ioremap_nocache(unsigned long offset, unsigned long
>  
>  #define ioremap_wc ioremap_nocache
>  #define ioremap_wt ioremap_nocache
> +#define ioremap_cache ioremap_nocache

>From the comment in ioremap_nocache(), ioremap() may be cacheable in
this arch.  

> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> index f56094cfdeff..a0665dfcab47 100644
> --- a/include/asm-generic/io.h
> +++ b/include/asm-generic/io.h
> @@ -793,6 +793,14 @@ static inline void __iomem *ioremap_wt(phys_addr_t offset, size_t size)
>  }
>  #endif
>  
> +#ifndef ioremap_cache
> +#define ioremap_cache ioremap_cache
> +static inline void __iomem *ioremap_cache(phys_addr_t offset, size_t size)
> +{
> +	return ioremap_nocache(offset, size);

Should this be defined as ioremap()?

> +}
> +#endif
> +
>  #ifndef iounmap
>  #define iounmap iounmap
>  
> diff --git a/include/asm-generic/iomap.h b/include/asm-generic/iomap.h
> index d8f8622fa044..f0f30464cecd 100644
> --- a/include/asm-generic/iomap.h
> +++ b/include/asm-generic/iomap.h
> @@ -70,6 +70,10 @@ extern void ioport_unmap(void __iomem *);
>  #define ioremap_wt ioremap_nocache
>  #endif
>  
> +#ifndef ARCH_HAS_IOREMAP_CACHE
> +#define ioremap_cache ioremap_nocache

Ditto.


Also, it'd be nice to remove ioremap_cached() and ioremap_fullcache()
with a separate patch in this opportunity.

Thanks,
-Toshi

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