ambiq,apollo4-pinctrl

Vendor: Ambiq Micro, Inc.

Description

The Ambiq Apollo4 pin controller is a node responsible for controlling
pin function selection and pin properties, such as routing a UART0 TX
to pin 60 and enabling the pullup resistor on that 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/ambiq-apollo4-pinctrl.h>

  &pinctrl {
    uart0_default: uart0_default {
      group1 {
        pinmux = <UART0TX_P60>;
      };
      group2 {
        pinmux = <UART0RX_P47>;
        input-enable;
      };
    };
  };

The 'uart0_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 'input-enable' property in group 2.

Properties

Top level properties

These property descriptions apply to “ambiq,apollo4-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

bias-high-impedance

boolean

high impedance mode ("third-state", "floating")

bias-pull-up

boolean

enable pull-up resistor

bias-pull-down

boolean

enable pull-down resistor

drive-push-pull

boolean

drive actively high and low

drive-open-drain

boolean

drive with open drain (hardware AND)

input-enable

boolean

enable input on pin (e.g. enable an input buffer, no effect on output)

pinmux

array

An array of pins sharing the same group properties. Each
element of the array is an integer constructed from the
pin number and the alternative function of the pin.

This property is required.

drive-strength

string

The drive strength of a pin, relative to full-driver strength.
The default value is 0.1, which is the reset value.

Default value: 0.1

Legal values: '0.1', '0.5', '0.75', '1.0'

slew-rate

string

Select slew rate for a pin. The default is slow, which is the reset value.

Default value: slow

Legal values: 'slow', 'fast'

ambiq,pull-up-ohms

int

The pullup resistor value. The default value is 1500 ohms.

Default value: 1500

Legal values: 1500, 6000, 12000, 24000, 50000, 100000

ambiq,iom-nce-module

int

IOM nCE module select. The default value is reset value.