linux-kernel - Re: [PATCH] add iommu_num

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Message-Id: <20080725221553Q.fujita.tomonori@lab.ntt.co.jp>
Date:	Fri, 25 Jul 2008 22:15:06 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	joerg.roedel@....com
Cc:	mingo@...hat.com, tglx@...utronix.de, linux-kernel@...r.kernel.org,
	iommu@...ts.linux-foundation.org, bhavna.sarathy@....com,
	robert.richter@....com, fujita.tomonori@....ntt.co.jp
Subject: Re: [PATCH] add iommu_num_pages helper function

On Fri, 25 Jul 2008 14:57:58 +0200
Joerg Roedel <joerg.roedel@....com> wrote:

> Calculating the number of pages from given address and length numbers is a task
> required in multiple IOMMU implementations. So implement this as a generic
> function into the IOMMU helper code.
> 
> Cc: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
> Signed-off-by: Joerg Roedel <joerg.roedel@....com>
> ---
>  include/linux/iommu-helper.h |    1 +
>  lib/iommu-helper.c           |    8 ++++++++
>  2 files changed, 9 insertions(+), 0 deletions(-)

Thanks. I planed to work on this after rc1. You beat me. :)

 
> diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
> index c975caf..f8598f5 100644
> --- a/include/linux/iommu-helper.h
> +++ b/include/linux/iommu-helper.h
> @@ -8,3 +8,4 @@ extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
>  				      unsigned long align_mask);
>  extern void iommu_area_free(unsigned long *map, unsigned long start,
>  			    unsigned int nr);
> +extern unsigned long iommu_num_pages(unsigned long addr, unsigned long len);
> diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
> index a3b8d4c..889ddce 100644
> --- a/lib/iommu-helper.c
> +++ b/lib/iommu-helper.c
> @@ -80,3 +80,11 @@ void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
>  	}
>  }
>  EXPORT_SYMBOL(iommu_area_free);
> +
> +unsigned long iommu_num_pages(unsigned long addr, unsigned long len)
> +{
> +	unsigned long size = roundup((addr & ~PAGE_MASK) + len, PAGE_SIZE);
> +
> +	return size >> PAGE_SHIFT;
> +}
> +EXPORT_SYMBOL(iommu_num_pages);

This doesn't work since PAGE_SIZE != IOMMU_PAGE_SIZE on the majority
of architectures.

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