> ## Documentation Index
> Fetch the complete documentation index at: https://dragonwingdocs.qualcomm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Buses

A bus facilitates data transfer among various system components. You can use the DT properties to configure the Qualcomm Universal Peripheral (QUP) v3 serial interface device nodes.

QUP v3 supports interintegrated circuit (I<sup>2</sup>C), serial peripheral interface (SPI), and universal asynchronous receiver-transmitter (UART) serial engines. The DT properties include the active and sleep settings for these serial engines.

For more information about QUP v3 and its peripheral interfaces, see [Overview of peripheral interfaces](https://dragonwingdocs.qualcomm.com/System/Interfaces/).

You can apply the serial engine protocol and active configurations when the firmware loads onto the serial engine.

You can configure the following Linux host files:

* `boot_images/boot/Settings/Soc/<chipset>/Core/Buses/qup_common/<chipset>-qupv3-pinctrl.dtsi`
* `boot_images/boot/Settings/Soc/<chipset>/Core/Buses/qup_common/<chipset>-qupv3.dtsi`

In `&top_qup{k}_se{n}`, **k** represents the QUP number and **n** represents the serial engine number. The table lists the DT properties:

<Frame caption="**Table: Bus DT properties**" />

| Property name                   | Property description                                                                                                       | Data type    | Possible values/value range             | Device behavior                                                  |
| ------------------------------- | -------------------------------------------------------------------------------------------------------------------------- | ------------ | --------------------------------------- | ---------------------------------------------------------------- |
| `status = "disabled";`          | Status control to enable/disable serial interfaces supported for QUP v3 serial engine (I<sup>2</sup>C/SPI/UART) protocols. | String       | <ul><li>Okay</li><li>Disabled</li></ul> | Enables or disables the serial engine.                           |
| `&top_qup{k}_se{n}_i2c_active`  | GPIOs active settings for I<sup>2</sup>C serial engines.                                                                   | UINT32-array | Reference to a node label.              | Sets active GPIO configurations for the I<sup>2</sup>C protocol. |
| `&top_qup{k}_se{n}_i2c_sleep`   | GPIOs sleep settings for I<sup>2</sup>C.                                                                                   | UINT32-array | Reference to a node label.              | Sets sleep GPIO configurations for the I<sup>2</sup>C protocol.  |
| `&top_qup{k}_se{n}_spi_active`  | GPIOs active settings for SPI.                                                                                             | UINT32-array | Reference to a node label.              | Sets active GPIO configurations for the SPI protocol.            |
| `&top_qup{k}_se{n}_spi_sleep`   | GPIOs sleep settings for SPI.                                                                                              | UINT32-array | Reference to a node label.              | Sets sleep GPIO configurations for the SPI protocol.             |
| `&top_qup{k}_se{n}_uart_active` | GPIOs active settings for UART.                                                                                            | UINT32-array | Reference to a node label.              | Sets active GPIO configurations for the UART protocol.           |
| `&top_qup{k}_se{n}_uart_sleep`  | GPIOs sleep settings for UART.                                                                                             | UINT32-array | Reference to a node label.              | Sets sleep GPIO configurations for the UART protocol.            |

## **Sample configuration**

```text theme={null}
TOP_QUP_0{}
/*TOP_QUP_0_SE_0 Instance */
TOP_QUP_0_SE_0
status = "disabled"; /* status to enable/disable SE0 Node */
pinctrl-0  = <&top_qup0_se0_i2c_active>;
pinctrl-1  = <&top_qup0_se0_i2c_sleep>;
pinctrl-2  = <&top_qup0_se0_spi_active>;
pinctrl-3  = <&top_qup0_se0_spi_sleep>;
pinctrl-4  = <&top_qup0_se0_uart_active>;
pinctrl-5  = <&top_qup0_se0_uart_sleep>;
```