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atmel,sam0-pinctrl

Vendor: Atmel Corporation

Description

Atmel SAM0 Pinctrl container node

The Atmel SAM0 pin controller is a singleton node responsible for controlling
pin function selection and pin properties. For example, you can use this node
to route SERCOM0 as UART were RX to pin PAD1 and enable the pull-up resistor
on the pin.

The node has the 'pinctrl' node label set in your SoC's devicetree, so you can
modify it like this:

  &pinctrl {
          /* your modifications go here */
  };

All device pin configurations should be placed in child nodes of the 'pinctrl'
node, as shown in this example:

  /** You can put this in places like a <board>-pinctrl.dtsi file in
    * your board directory, or a devicetree overlay in your application.
    */

  /** include pre-defined combinations for the SoC variant used by the board */
  #include <dt-bindings/pinctrl/samr21g-pinctrl.h>

  &pinctrl {
    /* configuration for the usart0 "default" state */
    sercom0_uart_default: sercom0_uart_default {
      /* group 1 */
      group1 {
        /* configure PA6 as USART0 TX and PA8 as USART0 CTS */
        pinmux = <PA5D_SERCOM0_PAD1>, <PA6D_SERCOM0_PAD2>;
      };
      /* group 2 */
      group2 {
        /* configure PA5 as USART0 RX and PA7 as USART0 RTS */
        pinmux = <PA4D_SERCOM0_PAD0>, <PA7D_SERCOM0_PAD3>;
        /* both PA5 and PA7 have pull-up enabled */
        bias-pull-up;
      };
    };
  };

The 'usart0_default' child node encodes the pin configurations for a
particular state of a device; in this case, the default (that is, active)
state.

As shown, pin configurations are organized in groups within each child node.
Each group can specify a list of pin function selections in the 'pinmux'
property.

A group can also specify shared pin properties common to all the specified
pins, such as the 'bias-pull-up' property in group 2. Here is a list of
supported standard pin properties:

- bias-pull-up: Enable pull-up resistor.
- bias-pull-down: Enable pull-down resistor.
- drive-strength: Increase sink current.
- input-enable: Enable input on pin.
- output-enable: Enable output on a pin without actively driving it.

To link pin configurations with a device, use a pinctrl-N property for some
number N, like this example you could place in your board's DTS file:

  #include "board-pinctrl.dtsi"

  &usart0 {
        pinctrl-0 = <&usart0_default>;
        pinctrl-names = "default";
  };

Properties

Top level properties

These property descriptions apply to “atmel,sam0-pinctrl” nodes themselves. This page also describes child node properties in the following sections.

Properties not inherited from the base binding file.

(None)

Grandchild node properties

Name

Type

Details

pinmux

array

An array of pins sharing the same group properties. The pins should
be defined using pre-defined macros or, alternatively, using the
SAM_PINMUX utility macros depending on the pinmux model used by the
SoC series.

This property is required.

drive-strength

int

The drive strength controls the output driver strength of an I/O pin
configured as an output.
  0: Pin drive strength is set to normal drive strength.
  1: Pin drive strength is set to stronger drive strength.

Legal values: 0, 1

bias-pull-up

boolean

enable pull-up resistor

bias-pull-down

boolean

enable pull-down resistor

input-enable

boolean

enable input on pin (no effect on output, such as enabling an input
buffer)

output-enable

boolean

enable output on a pin without actively driving it (such as enabling
an output buffer)