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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: "http://devicetree.org/schemas/serial/serial.yaml#"
$schema: "http://devicetree.org/meta-schemas/core.yaml#"
title: Serial Interface Generic DT Bindings
maintainers:
- Rob Herring <robh@kernel.org>
- Greg Kroah-Hartman <gregkh@linuxfoundation.org>
description:
This document lists a set of generic properties for describing UARTs in a
device tree. Whether these properties apply to a particular device depends
on the DT bindings for the actual device.
Each enabled UART may have an optional "serialN" alias in the "aliases" node,
where N is the port number (non-negative decimal integer) as printed on the
label next to the physical port.
properties:
$nodename:
pattern: "^serial(@.*)?$"
cts-gpios:
maxItems: 1
description:
Must contain a GPIO specifier, referring to the GPIO pin to be used as
the UART's CTS line.
dcd-gpios:
maxItems: 1
description:
Must contain a GPIO specifier, referring to the GPIO pin to be used as
the UART's DCD line.
dsr-gpios:
maxItems: 1
description:
Must contain a GPIO specifier, referring to the GPIO pin to be used as
the UART's DSR line.
dtr-gpios:
maxItems: 1
description:
Must contain a GPIO specifier, referring to the GPIO pin to be used as
the UART's DTR line.
rng-gpios:
maxItems: 1
description:
Must contain a GPIO specifier, referring to the GPIO pin to be used as
the UART's RNG line.
rts-gpios:
maxItems: 1
description:
Must contain a GPIO specifier, referring to the GPIO pin to be used as
the UART's RTS line.
uart-has-rtscts:
$ref: /schemas/types.yaml#/definitions/flag
description:
The presence of this property indicates that the UART has dedicated lines
for RTS/CTS hardware flow control, and that they are available for use
(wired and enabled by pinmux configuration). This depends on both the
UART hardware and the board wiring.
rx-tx-swap:
type: boolean
description: RX and TX pins are swapped.
cts-rts-swap:
type: boolean
description: CTS and RTS pins are swapped.
rx-threshold:
$ref: /schemas/types.yaml#/definitions/uint32
description:
RX FIFO threshold configuration (in bytes).
tx-threshold:
$ref: /schemas/types.yaml#/definitions/uint32
description:
TX FIFO threshold configuration (in bytes).
if:
required:
- uart-has-rtscts
then:
properties:
cts-gpios: false
rts-gpios: false
patternProperties:
".*":
if:
type: object
then:
description:
Serial attached devices shall be a child node of the host UART device
the slave device is attached to. It is expected that the attached
device is the only child node of the UART device. The slave device node
name shall reflect the generic type of device for the node.
properties:
compatible:
description:
Compatible of the device connected to the serial port.
max-speed:
$ref: /schemas/types.yaml#/definitions/uint32
description:
The maximum baud rate the device operates at.
This should only be present if the maximum is less than the slave
device can support. For example, a particular board has some
signal quality issue or the host processor can't support higher
baud rates.
current-speed:
$ref: /schemas/types.yaml#/definitions/uint32
description: |
The current baud rate the device operates at.
This should only be present in case a driver has no chance to know
the baud rate of the slave device.
Examples:
* device supports auto-baud
* the rate is setup by a bootloader and there is no way to reset
the device
* device baud rate is configured by its firmware but there is no
way to request the actual settings
required:
- compatible
additionalProperties: true
examples:
- |
serial@1234 {
compatible = "ns16550a";
reg = <0x1234 0x20>;
interrupts = <1>;
bluetooth {
compatible = "brcm,bcm4330-bt";
interrupt-parent = <&gpio>;
interrupts = <10>;
};
};
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