Documentation/devicetree/bindings/spi/sprd,spi-adi.yaml

# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)

%YAML 1.2
---
$id: "http://devicetree.org/schemas/spi/sprd,spi-adi.yaml#"
$schema: "http://devicetree.org/meta-schemas/core.yaml#"

title: Spreadtrum ADI controller

maintainers:
  - Orson Zhai <orsonzhai@gmail.com>
  - Baolin Wang <baolin.wang7@gmail.com>
  - Chunyan Zhang <zhang.lyra@gmail.com>

description: |
  ADI is the abbreviation of Anolog-Digital interface, which is used to access
  analog chip (such as PMIC) from digital chip. ADI controller follows the SPI
  framework for its hardware implementation is alike to SPI bus and its timing
  is compatile to SPI timing.

  ADI controller has 50 channels including 2 software read/write channels and
  48 hardware channels to access analog chip. For 2 software read/write channels,
  users should set ADI registers to access analog chip. For hardware channels,
  we can configure them to allow other hardware components to use it independently,
  which means we can just link one analog chip address to one hardware channel,
  then users can access the mapped analog chip address by this hardware channel
  triggered by hardware components instead of ADI software channels.

  Thus we introduce one property named "sprd,hw-channels" to configure hardware
  channels, the first value specifies the hardware channel id which is used to
  transfer data triggered by hardware automatically, and the second value specifies
  the analog chip address where user want to access by hardware components.

  Since we have multi-subsystems will use unique ADI to access analog chip, when
  one system is reading/writing data by ADI software channels, that should be under
  one hardware spinlock protection to prevent other systems from reading/writing
  data by ADI software channels at the same time, or two parallel routine of setting
  ADI registers will make ADI controller registers chaos to lead incorrect results.
  Then we need one hardware spinlock to synchronize between the multiple subsystems.

  The new version ADI controller supplies multiple master channels for different
  subsystem accessing, that means no need to add hardware spinlock to synchronize,
  thus change the hardware spinlock support to be optional to keep backward
  compatibility.

allOf:
  - $ref: /spi/spi-controller.yaml#

properties:
  compatible:
    enum:
      - sprd,sc9860-adi
      - sprd,sc9863-adi
      - sprd,ums512-adi

  reg:
    maxItems: 1

  hwlocks:
    maxItems: 1

  hwlock-names:
    const: adi

  sprd,hw-channels:
    $ref: /schemas/types.yaml#/definitions/uint32-matrix
    description: A list of hardware channels
    minItems: 1
    maxItems: 48
    items:
      items:
        - description: The hardware channel id which is used to transfer data
            triggered by hardware automatically, channel id 0-1 are for software
            use, 2-49 are hardware channels.
          minimum: 2
          maximum: 49
        - description: The analog chip address where user want to access by
            hardware components.

required:
  - compatible
  - reg
  - '#address-cells'
  - '#size-cells'

unevaluatedProperties: false

examples:
  - |
    aon {
        #address-cells = <2>;
        #size-cells = <2>;

        adi_bus: spi@40030000 {
            compatible = "sprd,sc9860-adi";
            reg = <0 0x40030000 0 0x10000>;
            hwlocks = <&hwlock1 0>;
            hwlock-names = "adi";
            #address-cells = <1>;
            #size-cells = <0>;
            sprd,hw-channels = <30 0x8c20>;
        };
    };
...