124 lines
4.0 KiB
YAML
124 lines
4.0 KiB
YAML
# Copyright (c) 2021 Teslabs Engineering S.L.
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# Copyright (c) 2021 Yonatan Schachter
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# SPDX-License-Identifier: Apache-2.0
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description: |
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The RPi Pico pin controller is a node responsible for controlling
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pin function selection and pin properties, such as routing a UART0 Rx
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to pin 1 and enabling the pullup resistor on that pin.
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The node has the 'pinctrl' node label set in your SoC's devicetree,
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so you can modify it like this:
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&pinctrl {
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/* your modifications go here */
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};
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All device pin configurations should be placed in child nodes of the
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'pinctrl' node, as shown in this example:
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/* You can put this in places like a board-pinctrl.dtsi file in
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* your board directory, or a devicetree overlay in your application.
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*/
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/* include pre-defined combinations for the SoC variant used by the board */
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#include <dt-bindings/pinctrl/rpi-pico-rp2040-pinctrl.h>
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&pinctrl {
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/* configuration for the usart0 "default" state */
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uart0_default: uart0_default {
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/* group 1 */
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group1 {
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/* configure P0 as UART0 TX */
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pinmux = <UART0_TX_P0>;
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};
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/* group 2 */
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group2 {
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/* configure P1 as UART0 RX */
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pinmux = <UART0_RX_P1>;
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/* enable input on pin 1 */
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input-enable;
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};
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};
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};
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The 'uart0_default' child node encodes the pin configurations for a
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particular state of a device; in this case, the default (that is, active)
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state.
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As shown, pin configurations are organized in groups within each child node.
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Each group can specify a list of pin function selections in the 'pinmux'
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property.
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A group can also specify shared pin properties common to all the specified
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pins, such as the 'input-enable' property in group 2. Here is a list of
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supported standard pin properties:
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- bias-disable: Disable pull-up/down (default, not required).
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- bias-pull-up: Enable pull-up resistor.
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- bias-pull-down: Enable pull-down resistor.
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- input-enable: Enable input from the pin.
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- input-schmitt-enable: Enable input hysteresys.
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- drive-strength: Set the drive strength of the pin, in milliamps. Possible
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values are: 2, 4, 8, 12 (default: 4mA)
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- slew-rate: If set to 0, slew rate is set to slow. If set to 1, it is set
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to fast.
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To link pin configurations with a device, use a pinctrl-N property for some
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number N, like this example you could place in your board's DTS file:
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#include "board-pinctrl.dtsi"
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&uart0 {
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pinctrl-0 = <&uart0_default>;
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pinctrl-1 = <&uart0_sleep>;
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pinctrl-names = "default", "sleep";
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};
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compatible: "raspberrypi,pico-pinctrl"
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include:
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- name: base.yaml
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- name: pincfg-node-group.yaml
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child-binding:
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child-binding:
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property-allowlist:
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- bias-disable
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- bias-pull-down
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- bias-pull-up
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- input-enable
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- input-schmitt-enable
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- drive-strength
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- slew-rate
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child-binding:
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description: |
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Definitions for a pinctrl state.
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child-binding:
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properties:
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pinmux:
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required: true
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type: array
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description: |
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An array of pins sharing the same group properties. Each
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element of the array is an integer constructed from the
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pin number and the alternative function of the pin.
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drive-strength:
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enum:
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- 2
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- 4
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- 8
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- 12
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default: 4
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description: |
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The drive strength of a pin, in mA. The default value is 4mA, as this
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is the power on reset value.
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slew-rate:
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enum:
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- 0
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- 1
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default: 0
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description: |
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The slew rate of a pin. 0 corresponds to slow, and 1 corresponds to fast.
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The default value is 0 (slow), as this is the power on reset value.
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