From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH 3/4 v4] iommu/fsl: Add iommu domain attributes required by fsl PAMU driver. Date: Mon, 5 Nov 2012 17:56:07 -0600 Message-ID: <1352159767.28279.11@snotra> References: <1352114361-25192-3-git-send-email-Varun.Sethi@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <1352114361-25192-3-git-send-email-Varun.Sethi@freescale.com> (from Varun.Sethi@freescale.com on Mon Nov 5 05:19:20 2012) Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Cc: joerg.roedel@amd.com, iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, timur@freescale.com, Varun Sethi List-Id: iommu@lists.linux-foundation.org On 11/05/2012 05:19:20 AM, Varun Sethi wrote: > Added the following domain attributes required by FSL PAMU driver: > 1. Subwindows field added to the iommu domain geometry attribute. > 2. Added new iommu stash attribute, which allows setting of the > LIODN specific stash id parameter through IOMMU API. > 3. Added an attribute for enabling/disabling DMA to a particular > memory window. > > > Signed-off-by: Varun Sethi > --- > changes in v4: > - Updated comment explaining subwindows(as mentioned by Scott). > change in v3: > -renamed the stash attribute targets > include/linux/iommu.h | 36 ++++++++++++++++++++++++++++++++++++ > 1 files changed, 36 insertions(+), 0 deletions(-) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index f3b99e1..e72f5e5 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -44,6 +44,34 @@ struct iommu_domain_geometry { > dma_addr_t aperture_start; /* First address that can be > mapped */ > dma_addr_t aperture_end; /* Last address that can be > mapped */ > bool force_aperture; /* DMA only allowed in mappable > range? */ > + > + /** > + * There could be a single contiguous window tha maps the entire > + * geometry or it could be split in to multiple subwindows. ...or it could be a normal IOMMU that supports arbitrary paging throughout the aperture. > + * Subwindows allow for supporting physically discontiguous > mappings. ...in the absence of arbitrary paging. > + * This attribute indicates number of DMA subwindows supported > by > + * the geometry. s/indicates number/indicates the number/ > If there is a single window that maps the entire > + * geometry, attribute must be set to "1". A value of "0" > implies > + * that there are 256 subwindows each of size 4K. Value other > than > + * "0" or "1" indicates the actual number of subwindows. No, a value of "0" indicates that this mechanism is not in use at all, and normal paging is used. PAMU specific things like "256 subwindows" must not be a default value in a generic API. In the case of PAMU, if you specify 0 here, the aperture is limited to 1 MiB because that is the limit of PAMU's ability to simulate arbitrary paging with subwindows, but this is only the limit of one implementation. It's not part of the API. -Scott