---
name: "ltc430x"
section: "4freebsd"
platform: "linux"
package: "freebsd-manpages"
version: "12.2-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/ltc430x/4freebsd"
---

# ltc430x(4freebsd)

driver for LTC4305 and LTC4306 I2C mux chips

## NAME

**ltc430x** – driver for LTC4305 and LTC4306 I2C mux chips

## SYNOPSIS

To compile this driver into the kernel, place the following line in your kernel configuration file:

**device ltc430x**

Alternatively, to load the driver as a module at boot time, place the following line in [loader.conf(5)](/loader.conf/5.md):

```
ltc430x_load="YES"
```

## DESCRIPTION

The **ltc430x** driver supports the LTC4305 and LTC4306 I2C bus multiplexer (mux) chips. It automatically connects an upstream I2C bus to one of several downstream buses as needed when slave devices on the downstream buses initiate I/O. More information on the automatic switching behavior is available in [iicmux(4)](/iicmux/4.md).

## FDT CONFIGURATION

On an [fdt(4)](/fdt/4.md) based system, an **ltc430x** device node is defined as a child node of its upstream i2c bus. The children of the **ltc430x** node are additional i2c buses, which will have their own i2c slave devices described in their child nodes.

The **ltc430x** driver conforms to the standard i2c/i2c-mux-ltc4306.txt bindings document, except that the following optional properties are not currently supported and will be ignored if present:

- enable-gpios

- gpio-controller

- \#gpio-cells

- ltc,downstream-accelerators-enable

- ltc,upstream-accelerators-enable

## HINTS CONFIGURATION

On a [device.hints(5)](/device.hints/5.md) based system, these values are configurable for **ltc430x**:

- *hint.ltc430x.\<unit\>.at*

  The upstream [iicbus(4)](/iicbus/4.md) the **ltc430x** instance is attached to.

When configured via hints, the driver automatically adds an iicbus instance for every downstream bus supported by the chip. There is currently no way to indicate used versus unused channels.

## SEE ALSO

[iicbus(4)](/iicbus/4.md), [iicmux(4)](/iicmux/4.md),

## HISTORY

The **ltc430x** driver first appeared in FreeBSD 13.0.