Documentation/devicetree/bindings/media/renesas,drif.yaml

Source file repositories/reference/linux-study-clean/Documentation/devicetree/bindings/media/renesas,drif.yaml

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Linux kernel
Corpus path
Documentation/devicetree/bindings/media/renesas,drif.yaml
Extension
.yaml
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9286 bytes
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270
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: configuration, schema, or hardware description
Status
atlas-only

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

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# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
%YAML 1.2
---
$id: http://devicetree.org/schemas/media/renesas,drif.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Renesas R-Car Gen3 Digital Radio Interface Controller (DRIF)

maintainers:
  - Ramesh Shanmugasundaram <rashanmu@gmail.com>
  - Fabrizio Castro <fabrizio.castro.jz@renesas.com>

description: |
  R-Car Gen3 DRIF is a SPI like receive only slave device. A general
  representation of DRIF interfacing with a master device is shown below.

  +---------------------+                +---------------------+
  |                     |-----SCK------->|CLK                  |
  |       Master        |-----SS-------->|SYNC  DRIFn (slave)  |
  |                     |-----SD0------->|D0                   |
  |                     |-----SD1------->|D1                   |
  +---------------------+                +---------------------+

  As per datasheet, each DRIF channel (drifn) is made up of two internal
  channels (drifn0 & drifn1). These two internal channels share the common
  CLK & SYNC. Each internal channel has its own dedicated resources like
  irq, dma channels, address space & clock. This internal split is not
  visible to the external master device.

  The device tree model represents each internal channel as a separate node.
  The internal channels sharing the CLK & SYNC are tied together by their
  phandles using a property called "renesas,bonding". For the rest of
  the documentation, unless explicitly stated, the word channel implies an
  internal channel.

  When both internal channels are enabled they need to be managed together
  as one (i.e.) they cannot operate alone as independent devices. Out of the
  two, one of them needs to act as a primary device that accepts common
  properties of both the internal channels. This channel is identified by a
  property called "renesas,primary-bond".

  To summarize,
     * When both the internal channels that are bonded together are enabled,
       the zeroth channel is selected as primary-bond. This channels accepts
       properties common to all the members of the bond.
     * When only one of the bonded channels need to be enabled, the property
       "renesas,bonding" or "renesas,primary-bond" will have no effect. That
       enabled channel can act alone as any other independent device.

properties:
  compatible:
    items:
      - enum:
          - renesas,r8a7795-drif        # R-Car H3
          - renesas,r8a7796-drif        # R-Car M3-W
          - renesas,r8a77965-drif       # R-Car M3-N
          - renesas,r8a77990-drif       # R-Car E3
      - const: renesas,rcar-gen3-drif   # Generic R-Car Gen3 compatible device

  reg:
    maxItems: 1

  interrupts:
    maxItems: 1

  clocks:
    maxItems: 1

  clock-names:
    const: fck

Annotation

Implementation Notes