55 lines
1.4 KiB
YAML
55 lines
1.4 KiB
YAML
# SPDX-License-Identifier: GPL-2.0
|
|
%YAML 1.2
|
|
---
|
|
$id: http://devicetree.org/schemas/firmware/qemu,fw-cfg-mmio.yaml#
|
|
$schema: http://devicetree.org/meta-schemas/core.yaml#
|
|
|
|
title: QEMU Firmware Configuration bindings
|
|
|
|
maintainers:
|
|
- Rob Herring <robh@kernel.org>
|
|
|
|
description: |
|
|
Various QEMU emulation / virtualization targets provide the following
|
|
Firmware Configuration interface on the "virt" machine type:
|
|
|
|
- A write-only, 16-bit wide selector (or control) register,
|
|
- a read-write, 64-bit wide data register.
|
|
|
|
QEMU exposes the control and data register to guests as memory mapped
|
|
registers; their location is communicated to the guest's UEFI firmware in the
|
|
DTB that QEMU places at the bottom of the guest's DRAM.
|
|
|
|
The authoritative guest-side hardware interface documentation to the fw_cfg
|
|
device can be found in "docs/specs/fw_cfg.txt" in the QEMU source tree.
|
|
|
|
|
|
properties:
|
|
compatible:
|
|
const: qemu,fw-cfg-mmio
|
|
|
|
reg:
|
|
maxItems: 1
|
|
description: |
|
|
* Bytes 0x0 to 0x7 cover the data register.
|
|
* Bytes 0x8 to 0x9 cover the selector register.
|
|
* Further registers may be appended to the region in case of future interface
|
|
revisions / feature bits.
|
|
|
|
dma-coherent: true
|
|
|
|
required:
|
|
- compatible
|
|
- reg
|
|
|
|
additionalProperties: false
|
|
|
|
examples:
|
|
- |
|
|
|
|
fw-cfg@9020000 {
|
|
compatible = "qemu,fw-cfg-mmio";
|
|
reg = <0x9020000 0xa>;
|
|
};
|
|
...
|