Documentation/devicetree/bindings/pci/host-generic-pci.yaml

Source file repositories/reference/linux-study-clean/Documentation/devicetree/bindings/pci/host-generic-pci.yaml

File Facts

System
Linux kernel
Corpus path
Documentation/devicetree/bindings/pci/host-generic-pci.yaml
Extension
.yaml
Size
6427 bytes
Lines
182
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: configuration, schema, or hardware description
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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Annotated Snippet

# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/pci/host-generic-pci.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Generic PCI host controller

maintainers:
  - Will Deacon <will@kernel.org>

description: |
  Firmware-initialised PCI host controllers and PCI emulations, such as the
  virtio-pci implementations found in kvmtool and other para-virtualised
  systems, do not require driver support for complexities such as regulator
  and clock management. In fact, the controller may not even require the
  configuration of a control interface by the operating system, instead
  presenting a set of fixed windows describing a subset of IO, Memory and
  Configuration Spaces.

  Configuration Space is assumed to be memory-mapped (as opposed to being
  accessed via an ioport) and laid out with a direct correspondence to the
  geography of a PCI bus address by concatenating the various components to
  form an offset.

  For CAM, this 24-bit offset is:

          cfg_offset(bus, device, function, register) =
                     bus << 16 | device << 11 | function << 8 | register

  While ECAM extends this by 4 bits to accommodate 4k of function space:

          cfg_offset(bus, device, function, register) =
                     bus << 20 | device << 15 | function << 12 | register

properties:
  compatible:
    description: Depends on the layout of configuration space (CAM vs ECAM
      respectively). May also have more specific compatibles.
    oneOf:
      - description:
          PCIe host controller in Arm Juno based on PLDA XpressRICH3-AXI IP
        items:
          - const: arm,juno-r1-pcie
          - const: plda,xpressrich3-axi
          - const: pci-host-ecam-generic
      - description: |
          ThunderX PCI host controller for pass-1.x silicon

          Firmware-initialized PCI host controller to on-chip devices found on
          some Cavium ThunderX processors.  These devices have ECAM-based config
          access, but the BARs are all at fixed addresses.  We handle the fixed
          addresses by synthesizing Enhanced Allocation (EA) capabilities for
          these devices.
        const: cavium,pci-host-thunder-ecam
      - description:
          Cavium ThunderX PEM firmware-initialized PCIe host controller
        const: cavium,pci-host-thunder-pem
      - description:
          HiSilicon Hip06/Hip07 PCIe host bridge in almost-ECAM mode. Some
          firmware places the host controller in a mode where it is ECAM
          compliant for all devices other than the root complex.
        enum:
          - hisilicon,hip06-pcie-ecam
          - hisilicon,hip07-pcie-ecam
      - description: |
          In some cases, firmware may already have configured the Synopsys
          DesignWare PCIe controller in RC mode with static ATU window mappings
          that cover all config, MMIO and I/O spaces in a [mostly] ECAM
          compatible fashion. In this case, there is no need for the OS to

Annotation

Implementation Notes