On 31.05.22 14:52, Krzysztof Kozlowski wrote:
Hello Krzysztof
On 30/05/2022 23:00, Oleksandr Tyshchenko wrote:
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Thank you for your patch. There is something to discuss/improve.
diff --git a/Documentation/devicetree/bindings/iommu/xen,grant-dma.yaml b/Documentation/devicetree/bindings/iommu/xen,grant-dma.yaml
new file mode 100644
index 00000000..ab5765c
--- /dev/null
+++ b/Documentation/devicetree/bindings/iommu/xen,grant-dma.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iommu/xen,grant-dma.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xen specific IOMMU for virtualized devices (e.g. virtio)
+
+maintainers:
+ - Stefano Stabellini <sstabellini@xxxxxxxxxx>
+
+description:
+ The reference to Xen specific IOMMU node using "iommus" property indicates
+ that Xen grant mappings need to be enabled for the device, and it specifies
+ the ID of the domain where the corresponding backend resides.
+ The binding is required to restrict memory access using Xen grant mappings.
+
+properties:
+ compatible:
+ const: xen,grant-dma
+
+ '#iommu-cells':
+ const: 1
+ description:
+ Xen specific IOMMU is multiple-master IOMMU device.
+ The single cell describes the domid (domain ID) of the domain where
+ the backend is running.
+
+required:
+ - compatible
+ - "#iommu-cells"
+
+additionalProperties: false
+
+examples:
+ - |
+ xen_iommu {
No underscores in node names, generic node names, so this looks like
"iommu".
ok, will change
+ compatible = "xen,grant-dma";
+ #iommu-cells = <1>;
+ };
+
+ virtio@3000 {
+ compatible = "virtio,mmio";
+ reg = <0x3000 0x100>;
+ interrupts = <41>;
+
+ /* The backend is located in Xen domain with ID 1 */
+ iommus = <&xen_iommu 1>;
There is no need usually to give consumer examples in provider binding.
If there is nothing specific here (looks exactly like every IOMMU
consumer in Linux kernel), drop the consumer.
I got it. There is nothing specific from the device tree's perspective,
I was thinking to draw attention to the IOMMU specifier (in our case,
the master device's ID == backend's domain ID). But '#iommu-cells'
description above already clarifies that. Will drop.
+ };
Best regards,
Krzysztof
--
Regards,
Oleksandr Tyshchenko
