Overview

The aim of this document is to explain how to setup pins of SP7350 in device-tree source. SP7350 has 106 general purpose IO (GPIO) pins which are multiplexed with other special functions, like eMMC device, SPI-NOR flash, SPI-NAND flash, Ethernet PHY (RGMII or RMII interface), UART, I2C pins, and etc.

The following sections will explain how to setup GPIOs and special function pins in device-tree source file. Note that the same device-tree source file is used by U-Boot and Linux in SP7350. Both Pinctrl drivers support generic helper bindings.

Properties

function

The function to be applied on particular pins or groups. See section "Functions" below.

pins

The pins to apply the properties to. See section "Pins" below.

groups

The groups to apply the properties to. See section "Groups" below.

Functions

We define a bunch of functions as listed in appendix Function-group Table below.

Pins

...

IO Pins

In the Linux, name of IO pin is in form of GPIO(id), like GPIO0, GPIO1, GPIO2, GPIO99…, GPIO105, and etc. There are two kinds of GPIO pins. One is 1.8V GPIO pins, and the other is 1.8V/3.0V Dual Voltage IO (DVIO) pins. Beside configure 1.8V or 3.0V power to power supply of a DVIO group in your circuit boards (hardware), you need to setup Voltage Mode Select (MS control) in device-tree source. Refer to groups of GPIO and DVIO in appendix GPIO Table below in details.

Groups

We define a bunch of groups as listed in appendix Function-group Table below.

Voltage Mode Select

For These IO pins of SP7350 are categorized, based on their operating voltage, into two groups:

• Single-supply IO pins: The IO pins operate on a single power supply, specifically at 1.8V.

• Dual-supply IO pins: The IO pins offer a dual power supply option, supporting both 1.8V and 3.0V. These pins are referred to as DVIO pins in the subsequent sections.

Refer to table below for a breakdown of power domain, supplying voltage, pin name (hardware pin name), supplying power pins of all IO pins of SP7350:

...

...

pinmux

1. Set a single pin to function "GPIO"

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Voltage Mode Select

Beyond configuring the 1.8V or 3.0V power to supply pins of a DVIO group in circuit boards (hardware), setting up the voltage mode select (ms control) control-bits is crucial for the normal operation of IO pins. The following properties configure voltage mode select control-bits in the Device Tree Source (DTS) file:

These properties should be set in the pinctrl node in the DTS file. For example:

pctl: pinctrl@f8800080 {
		:
		:
		sunplus,ms-dvio-group-0 = “1V8“;
		sunplus,ms-dvio-group-1 = “3V0“;
		sunplus,ms-dvio-ao-group-2 = “1V8“;
		:
};

Default voltage is “3V0”.

Pin Multiplexing Nodes

• function - the multiplex function to select.

• groups - the list of groups to select with this function. Either this or "pins" must be specified.

• pins - the list of pins to select with this function. Either this or "groups" must be specified.

Refer to examples below:

Set a single pin to GPIO function

pinmux_example {
    function = "GPIO";
    pins = "GPIO0";
};

Set pin GPIO0 to GPIO function.

Set several pins to

...

GPIO

...

function

...

Code Block
language c
pinmux_example { function = "GPIO"; pins = "GPIO0", "GPIO1", "GPIO10"; };

Set pins GPIO0, GPIO1, GPIO10 to GPIO function.

Set a group of pins to a

...

specified function

• set group "UART0_X1" to function "UART0"

pinmux_example {
    function = "UART0";
    groups = "UART0_X1";
};

...

Set a group of pins, whose group-name is UART0_X1, to UART0 function. Actually, the group includes pins GPIO50 and GPIO51.

Refer to Function-group Table in appendix.

Pin Configuration Nodes

...

pinconf_example {
	:
    :
    sunplus,bias-strong-pull-up;
    :
    :
};

DTS Files

Device-tree source files of SP7350 are located in linux/kernel/arch/arm64/boot/dts/sunplus/.

...

Example

Voltage Mode Select

...

Every device should have a node in device-tree source (dts) file in Linux. Property pinctrl-0 (or pinctrl-1, pinctrl-2,… if a device has more states) is used to point at pin configuration node within pin controller (node pinctrl@f8800080 in SP7021). Pin configuration nodes (sub-nodes in node pinctrl@f8800080 ) define the actual pins assignment. For examples:

pinmux

1. eMMC device:

Pins of eMMC of SP7350, [D5, D3, D4, D0, D1, CLK, D2, D7, D6, CMD, DS], can be multiplexed to pin-group GPIO [20, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37].

...

Refer to "Function-group Table" in Appendix.

pinconf

1. One configuration to all pins.

...

uart7_pins: pinmux_uart7-pins {
    function = "UART7";
    groups = "UART7";
    drive-strength-microamp = <SPPCTRL_GPIO_DRV_IOH_6600_IOL_6600UA>;
};

Refer to Driving-strength Table of GPIO and Driving-strength Table of DVIO in Appendix.

Appendix

List of support properties

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Properties

...

Values

...

Descriptions

...

bias-disable

...

NA

...

Disable pull-up, pull-down and strong pull-up

...

bias-high-impedance

...

NA

...

bias-pull-up

...

NA

...

bias-pull-down

...

NA

...

drive-open-drain

...

NA

...

For GPIO or DVIO

...

drive-strength-microamp

...

 = "UART7";
    groups = "UART7";
    drive-strength-microamp = <SPPCTRL_GPIO_DRV_IOH_6600_IOL_6600UA>;
};

...

pins

...

“GPIO0” ~ “GPIO105”

...

Refer to Driving-strength Table of GPIO and

...

function

...

…

...

Refer to Function-group Table

...

groups

...

…

...

Refer to Function-group Table

...

input-disable

...

NA

...

For GPIO or DVIO

...

input-enable

...

NA

...

For GPIO or DVIO

...

input-schmitt-disable

...

NA

...

input-schmitt-enable

...

NA

...

output-disable

...

NA

...

For GPIO or DVIO

...

output-enable

...

NA

...

For GPIO or DVIO

...

output-high

...

NA

...

For GPIO or DVIO

...

output-low

...

NA

...

For GPIO or DVIO

Driving-strength Table of DVIO in Appendix.

Appendix

List of support properties

GPIO Table

Driving-strength Table of GPIO

...