xref: /linux/Documentation/devicetree/bindings/serial/serial.yaml (revision 55d0969c451159cff86949b38c39171cab962069) 
1# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/serial/serial.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: Serial Interface Generic
8
9maintainers:
10  - Rob Herring <robh@kernel.org>
11  - Greg Kroah-Hartman <gregkh@linuxfoundation.org>
12
13description:
14  This document lists a set of generic properties for describing UARTs in a
15  device tree.  Whether these properties apply to a particular device depends
16  on the DT bindings for the actual device.
17
18  Each enabled UART may have an optional "serialN" alias in the "aliases" node,
19  where N is the port number (non-negative decimal integer) as printed on the
20  label next to the physical port.
21
22properties:
23  $nodename:
24    pattern: "^serial(@.*)?$"
25
26  label: true
27
28  cts-gpios:
29    maxItems: 1
30    description:
31      Must contain a GPIO specifier, referring to the GPIO pin to be used as
32      the UART's CTS line.
33
34  dcd-gpios:
35    maxItems: 1
36    description:
37      Must contain a GPIO specifier, referring to the GPIO pin to be used as
38      the UART's DCD line.
39
40  dsr-gpios:
41    maxItems: 1
42    description:
43      Must contain a GPIO specifier, referring to the GPIO pin to be used as
44      the UART's DSR line.
45
46  dtr-gpios:
47    maxItems: 1
48    description:
49      Must contain a GPIO specifier, referring to the GPIO pin to be used as
50      the UART's DTR line.
51
52  rng-gpios:
53    maxItems: 1
54    description:
55      Must contain a GPIO specifier, referring to the GPIO pin to be used as
56      the UART's RNG line.
57
58  rts-gpios:
59    maxItems: 1
60    description:
61      Must contain a GPIO specifier, referring to the GPIO pin to be used as
62      the UART's RTS line.
63
64  uart-has-rtscts:
65    $ref: /schemas/types.yaml#/definitions/flag
66    description:
67      The presence of this property indicates that the UART has dedicated lines
68      for RTS/CTS hardware flow control, and that they are available for use
69      (wired and enabled by pinmux configuration).  This depends on both the
70      UART hardware and the board wiring.
71
72  rx-tx-swap:
73    type: boolean
74    description: RX and TX pins are swapped.
75
76  cts-rts-swap:
77    type: boolean
78    description: CTS and RTS pins are swapped.
79
80  rx-threshold:
81    $ref: /schemas/types.yaml#/definitions/uint32
82    description:
83      RX FIFO threshold configuration (in bytes).
84
85  tx-threshold:
86    $ref: /schemas/types.yaml#/definitions/uint32
87    description:
88      TX FIFO threshold configuration (in bytes).
89
90patternProperties:
91  "^(bluetooth|bluetooth-gnss|embedded-controller|gnss|gps|mcu|onewire)$":
92    if:
93      type: object
94    then:
95      additionalProperties: true
96      $ref: serial-peripheral-props.yaml#
97      description:
98        Serial attached devices shall be a child node of the host UART device
99        the slave device is attached to. It is expected that the attached
100        device is the only child node of the UART device. The slave device node
101        name shall reflect the generic type of device for the node.
102
103      properties:
104        compatible:
105          description:
106            Compatible of the device connected to the serial port.
107
108      required:
109        - compatible
110
111if:
112  required:
113    - uart-has-rtscts
114then:
115  properties:
116    cts-gpios: false
117    rts-gpios: false
118
119additionalProperties: true
120
121examples:
122  - |
123    serial@1234 {
124        compatible = "ns16550a";
125        reg = <0x1234 0x20>;
126        interrupts = <1>;
127
128        bluetooth {
129            compatible = "brcm,bcm4330-bt";
130            interrupt-parent = <&gpio>;
131            interrupts = <10>;
132        };
133    };
134