From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Philippe Brucker Subject: [PATCH v3 1/7] dt-bindings: virtio-mmio: Add IOMMU description Date: Fri, 12 Oct 2018 15:59:11 +0100 Message-ID: <20181012145917.6840-2-jean-philippe.brucker__41542.078057728$1539356349$gmane$org@arm.com> References: <20181012145917.6840-1-jean-philippe.brucker@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181012145917.6840-1-jean-philippe.brucker@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: iommu@lists.linux-foundation.org, virtualization@lists.linux-foundation.org, devicetree@vger.kernel.org Cc: mark.rutland@arm.com, peter.maydell@linaro.org, lorenzo.pieralisi@arm.com, tnowicki@caviumnetworks.com, mst@redhat.com, marc.zyngier@arm.com, linux-pci@vger.kernel.org, will.deacon@arm.com, kvmarm@lists.cs.columbia.edu, eric.auger@redhat.com, robh+dt@kernel.org, robin.murphy@arm.com, joro@8bytes.org List-Id: virtualization@lists.linuxfoundation.org The nature of a virtio-mmio node is discovered by the virtio driver at probe time. However the DMA relation between devices must be described statically. When a virtio-mmio node is a virtio-iommu device, it needs an "#iommu-cells" property as specified by bindings/iommu/iommu.txt. Otherwise, the virtio-mmio device may perform DMA through an IOMMU, which requires an "iommus" property. Describe these requirements in the device-tree bindings documentation. Signed-off-by: Jean-Philippe Brucker --- .../devicetree/bindings/virtio/mmio.txt | 30 +++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/Documentation/devicetree/bindings/virtio/mmio.txt b/Documentation/devicetree/bindings/virtio/mmio.txt index 5069c1b8e193..748595473b36 100644 --- a/Documentation/devicetree/bindings/virtio/mmio.txt +++ b/Documentation/devicetree/bindings/virtio/mmio.txt @@ -8,10 +8,40 @@ Required properties: - reg: control registers base address and size including configuration space - interrupts: interrupt generated by the device +Required properties for virtio-iommu: + +- #iommu-cells: When the node corresponds to a virtio-iommu device, it is + linked to DMA masters using the "iommus" or "iommu-map" + properties [1][2]. #iommu-cells specifies the size of the + "iommus" property. For virtio-iommu #iommu-cells must be + 1, each cell describing a single endpoint ID. + +Optional properties: + +- iommus: If the device accesses memory through an IOMMU, it should + have an "iommus" property [1]. Since virtio-iommu itself + does not access memory through an IOMMU, the "virtio,mmio" + node cannot have both an "#iommu-cells" and an "iommus" + property. + Example: virtio_block@3000 { compatible = "virtio,mmio"; reg = <0x3000 0x100>; interrupts = <41>; + + /* Device has endpoint ID 23 */ + iommus = <&viommu 23> } + + viommu: virtio_iommu@3100 { + compatible = "virtio,mmio"; + reg = <0x3100 0x100>; + interrupts = <42>; + + #iommu-cells = <1> + } + +[1] Documentation/devicetree/bindings/iommu/iommu.txt +[2] Documentation/devicetree/bindings/pci/pci-iommu.txt -- 2.19.1