Re: [PATCH v5 02/13] dt-bindings: Add binding for gunyah hypervisor

Rob Herring
2022-10-12T15:56:52Z

On Mon, Oct 10, 2022 at 05:08:29PM -0700, Elliot Berman wrote:
> When Linux is booted as a guest under the Gunyah hypervisor, the Gunyah
> Resource Manager applies a devicetree overlay describing the virtual
> platform configuration of the guest VM, such as the message queue
> capability IDs for communicating with the Resource Manager. This
> information is not otherwise discoverable by a VM: the Gunyah hypervisor
> core does not provide a direct interface to discover capability IDs nor
> a way to communicate with RM without having already known the
> corresponding message queue capability ID. Add the DT bindings that
> Gunyah adheres for the hypervisor node and message queues.
>
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> ---
> .../bindings/firmware/gunyah-hypervisor.yaml | 87 +++++++++++++++++++
> MAINTAINERS | 1 +
> 2 files changed, 88 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
>
> diff --git a/Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml b/Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
> new file mode 100644
> index 000000000000..f0a14101e2fd
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
> @@ -0,0 +1,87 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/firmware/gunyah-hypervisor.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Gunyah Hypervisor
> +
> +maintainers:
> + - Murali Nalajala <quic_mnalajal@quicinc.com>
> + - Elliot Berman <quic_eberman@quicinc.com>
> +
> +description: |+
> + On systems which support devicetree, Gunyah generates and overlays a deviceetree overlay which

How you end up with the node (applying an overlay) is not relavent to
the binding.

> + describes the basic configuration of the hypervisor. Virtual machines use this information to determine
> + the capability IDs of the message queues used to communicate with the Gunyah Resource Manager.

Wrap at 80. That is the coding standard still though 100 is deemed
allowed. And yamllint only complains at 110 because I didn't care to fix
everyones lines over 100.

> + See also: https://github.com/quic/gunyah-resource-manager/blob/develop/src/vm_creation/dto_construct.c
> +
> +properties:
> + compatible:
> + items:
> + - const: gunyah-hypervisor-1.0
> + - const: gunyah-hypervisor

2 compatibles implies a difference between the 2. What's the difference?
Where does '1.0' come from?

> +
> + "#address-cells":
> + description: Number of cells needed to represent 64-bit capability IDs.
> + const: 2
> +
> + "#size-cells":
> + description: must be 0, because capability IDs are not memory address
> + ranges and do not have a size.
> + const: 0
> +
> +patternProperties:
> + "^gunyah-resource-mgr(@.*)?":
> + type: object
> + description:
> + Resource Manager node which is required to communicate to Resource
> + Manager VM using Gunyah Message Queues.
> +
> + properties:
> + compatible:
> + items:
> + - const: gunyah-resource-manager-1-0
> + - const: gunyah-resource-manager

Same comment here.

> +
> + reg:
> + items:
> + - description: Gunyah capability ID of the TX message queue
> + - description: Gunyah capability ID of the RX message queue
> +
> + interrupts:
> + items:
> + - description: Interrupt for the TX message queue
> + - description: Interrupt for the RX message queue
> +
> + additionalProperties: false
> +
> + required:
> + - compatible
> + - reg
> + - interrupts
> +
> +additionalProperties: false
> +
> +required:
> + - compatible
> + - "#address-cells"
> + - "#size-cells"
> +
> +examples:
> + - |
> + #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> + hypervisor {
> + #address-cells = <2>;
> + #size-cells = <0>;
> + compatible = "gunyah-hypervisor-1.0", "gunyah-hypervisor";
> +
> + gunyah-resource-mgr@0 {
> + compatible = "gunyah-resource-manager-1-0", "gunyah-resource-manager";
> + interrupts = <GIC_SPI 3 IRQ_TYPE_EDGE_RISING>, /* TX full IRQ */
> + <GIC_SPI 4 IRQ_TYPE_EDGE_RISING>; /* RX empty IRQ */
> + reg = <0x00000000 0x00000000>, <0x00000000 0x00000001>;
> + /* TX, RX cap ids */
> + };
> + };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 91d00b00d91c..ef6de7599d98 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8884,6 +8884,7 @@ M: Elliot Berman <quic_eberman@quicinc.com>
> M: Murali Nalajala <quic_mnalajal@quicinc.com>
> L: linux-arm-msm@vger.kernel.org
> S: Supported
> +F: Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml
> F: Documentation/virt/gunyah/
>
> HABANALABS PCI DRIVER
> --
> 2.25.1
>
>