| Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame^] | 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 | |
| 7 | title: Serial Interface Generic |
| 8 | |
| 9 | maintainers: |
| 10 | - Rob Herring <robh@kernel.org> |
| 11 | - Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| 12 | |
| 13 | description: |
| 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 | |
| 22 | properties: |
| 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 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 87 | description: |
| 88 | TX FIFO threshold configuration (in bytes). |
| 89 | |
| 90 | patternProperties: |
| 91 | "^(bluetooth|bluetooth-gnss|gnss|gps|mcu)$": |
| 92 | if: |
| 93 | type: object |
| 94 | then: |
| 95 | description: |
| 96 | Serial attached devices shall be a child node of the host UART device |
| 97 | the slave device is attached to. It is expected that the attached |
| 98 | device is the only child node of the UART device. The slave device node |
| 99 | name shall reflect the generic type of device for the node. |
| 100 | |
| 101 | properties: |
| 102 | compatible: |
| 103 | description: |
| 104 | Compatible of the device connected to the serial port. |
| 105 | |
| 106 | max-speed: |
| 107 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 108 | description: |
| 109 | The maximum baud rate the device operates at. |
| 110 | This should only be present if the maximum is less than the slave |
| 111 | device can support. For example, a particular board has some |
| 112 | signal quality issue or the host processor can't support higher |
| 113 | baud rates. |
| 114 | |
| 115 | current-speed: |
| 116 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 117 | description: | |
| 118 | The current baud rate the device operates at. |
| 119 | This should only be present in case a driver has no chance to know |
| 120 | the baud rate of the slave device. |
| 121 | Examples: |
| 122 | * device supports auto-baud |
| 123 | * the rate is setup by a bootloader and there is no way to reset |
| 124 | the device |
| 125 | * device baud rate is configured by its firmware but there is no |
| 126 | way to request the actual settings |
| 127 | |
| 128 | required: |
| 129 | - compatible |
| 130 | |
| 131 | if: |
| 132 | required: |
| 133 | - uart-has-rtscts |
| 134 | then: |
| 135 | properties: |
| 136 | cts-gpios: false |
| 137 | rts-gpios: false |
| 138 | |
| 139 | additionalProperties: true |
| 140 | |
| 141 | examples: |
| 142 | - | |
| 143 | serial@1234 { |
| 144 | compatible = "ns16550a"; |
| 145 | reg = <0x1234 0x20>; |
| 146 | interrupts = <1>; |
| 147 | |
| 148 | bluetooth { |
| 149 | compatible = "brcm,bcm4330-bt"; |
| 150 | interrupt-parent = <&gpio>; |
| 151 | interrupts = <10>; |
| 152 | }; |
| 153 | }; |