Re: [RFC/PATCH 2/7] iommu-api: Add map_range/unmap_range functions

From: Thierry Reding <thierry.reding@gmail.com>
To: Olav Haugan <ohaugan@codeaurora.org>
Cc: linux-arm-kernel@lists.infradead.org,
	iommu@lists.linux-foundation.org, linux-arm-msm@vger.kernel.org,
	will.deacon@arm.com, joro@8bytes.org, vgandhi@codeaurora.org
Subject: Re: [RFC/PATCH 2/7] iommu-api: Add map_range/unmap_range functions
Date: Mon, 30 Jun 2014 21:42:10 +0200	[thread overview]
Message-ID: <20140630194209.GC32594@mithrandir> (raw)
In-Reply-To: <1404147116-4598-3-git-send-email-ohaugan@codeaurora.org>

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On Mon, Jun 30, 2014 at 09:51:51AM -0700, Olav Haugan wrote:
[...]
> +int iommu_map_range(struct iommu_domain *domain, unsigned int iova,
> +		    struct scatterlist *sg, unsigned int len, int prot)
> +{
> +	if (unlikely(domain->ops->map_range == NULL))
> +		return -ENODEV;

Should we perhaps make this mandatory? For drivers that don't provide it
we could implement a generic helper that wraps iommu_{map,unmap}().

> +
> +	BUG_ON(iova & (~PAGE_MASK));
> +
> +	return domain->ops->map_range(domain, iova, sg, len, prot);
> +}
> +EXPORT_SYMBOL_GPL(iommu_map_range);
> +
> +int iommu_unmap_range(struct iommu_domain *domain, unsigned int iova,
> +		      unsigned int len)
> +{
> +	if (unlikely(domain->ops->unmap_range == NULL))
> +		return -ENODEV;
> +
> +	BUG_ON(iova & (~PAGE_MASK));
> +
> +	return domain->ops->unmap_range(domain, iova, len);
> +}
> +EXPORT_SYMBOL_GPL(iommu_unmap_range);

Could these be renamed iommu_{map,unmap}_sg() instead to make it more
obvious what exactly they map? And perhaps this could take an sg_table
instead, which already provides a count and is a very common structure
used in drivers (and the DMA mapping API).

Thierry

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