Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml

Source file repositories/reference/linux-study-clean/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml

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System
Linux kernel
Corpus path
Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml
Extension
.yaml
Size
3710 bytes
Lines
145
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/gpio/nxp,pcf8575.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: PCF857x-compatible I/O expanders

maintainers:
  - Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

description:
  The PCF857x-compatible chips have "quasi-bidirectional" I/O lines that can be
  driven high by a pull-up current source or driven low to ground. This
  combines the direction and output level into a single bit per line, which
  can't be read back. We can't actually know at initialization time whether a
  line is configured (a) as output and driving the signal low/high, or (b) as
  input and reporting a low/high value, without knowing the last value written
  since the chip came out of reset (if any). The only reliable solution for
  setting up line direction is thus to do it explicitly.

properties:
  compatible:
    enum:
      - maxim,max7328
      - maxim,max7329
      - nxp,pca8574
      - nxp,pca8575
      - nxp,pca9670
      - nxp,pca9671
      - nxp,pca9672
      - nxp,pca9673
      - nxp,pca9674
      - nxp,pca9675
      - nxp,pcf8574
      - nxp,pcf8574a
      - nxp,pcf8575

  reg:
    maxItems: 1

  gpio-line-names:
    minItems: 1
    maxItems: 16

  gpio-controller: true

  '#gpio-cells':
    const: 2
    description:
      The first cell is the GPIO number and the second cell specifies GPIO
      flags, as defined in <dt-bindings/gpio/gpio.h>. Only the GPIO_ACTIVE_HIGH
      and GPIO_ACTIVE_LOW flags are supported.

  lines-initial-states:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      Bitmask that specifies the initial state of each line.
      When a bit is set to zero, the corresponding line will be initialized to
      the input (pulled-up) state.
      When the  bit is set to one, the line will be initialized to the
      low-level output state.
      If the property is not specified all lines will be initialized to the
      input state.

  interrupts:
    maxItems: 1

  interrupt-controller: true

Annotation

Implementation Notes