From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753931AbaETP1H (ORCPT ); Tue, 20 May 2014 11:27:07 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:50963 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751662AbaETP1E (ORCPT ); Tue, 20 May 2014 11:27:04 -0400 Date: Tue, 20 May 2014 16:26:59 +0100 From: Will Deacon To: Arnd Bergmann Cc: Dave P Martin , Thierry Reding , Mark Rutland , "devicetree@vger.kernel.org" , "linux-samsung-soc@vger.kernel.org" , Pawel Moll , Ian Campbell , Grant Grundler , Joerg Roedel , Stephen Warren , "linux-kernel@vger.kernel.org" , Marc Zyngier , "iommu@lists.linux-foundation.org" , Rob Herring , Kumar Gala , "linux-tegra@vger.kernel.org" , Cho KyongHo , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH] devicetree: Add generic IOMMU device tree bindings Message-ID: <20140520152659.GA30404@arm.com> References: <1400242998-437-1-git-send-email-thierry.reding@gmail.com> <5080348.QmhgfQRxZW@wuerfel> <20140520130659.GA5041@e103592.cambridge.arm.com> <6382280.3uMvoxaUSK@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6382280.3uMvoxaUSK@wuerfel> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 20, 2014 at 02:23:47PM +0100, Arnd Bergmann wrote: > Bit# 33222222 22221111 11111100 00000000 > 10987654 32109876 54321098 76543210 > phys.hi cell: npt000ss bbbbbbbb dddddfff rrrrrrrr > phys.mid cell: hhhhhhhh hhhhhhhh hhhhhhhh hhhhhhhh > phys.lo cell: llllllll llllllll llllllll llllllll > > where: > n is 0 if the address is relocatable, 1 otherwise > p is 1 if the addressable region is "prefetchable", 0 otherwise > t is 1 if the address is aliased (for non-relocatable I/O), > below 1 MB (for Memory), or below 64 KB (for relocatable I/O). > ss is the space code, denoting the address space > bbbbbbbb is the 8-bit Bus Number > ddddd is the 5-bit Device Number > fff is the 3-bit Function Number > rrrrrrrr is the 8-bit Register Number > hh...hh is a 32-bit unsigned number > ll...ll is a 32-bit unsigned number > > We can ignore n, p, t and r here, and use the same format for a DMA > address, then define an empty "dma-ranges" property. That would > imply that using b/d/f is sufficient to identify each master at the > iommu. Any device outside of the PCI host but connected to the same > iommu can use the same notation to list the logical b/d/f that gets > sent to the IOMMU in bus master transactions. > > Do you think this is sufficient for the ARM SMMU, or do we need > something beyond that? I think it can define the common-cases for the existing implementations, yes. I anticipate Stream-IDs becoming > 16-bit in the near future though, so we'd need extra bits if we're describing other devices coming into the SMMU. Note that we already have a binding for the current SMMU driver, so I'm not really in a position to shift over to a new binding until the next version of the SMMU architecture comes along... Will