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):

           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).

FDT CONFIGURATION

     On an fdt(4) 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) based system, these values are configurable for ltc430x:

     hint.ltc430x.<unit>.at
             The upstream iicbus(4) 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), iicmux(4),

HISTORY

     The ltc430x driver first appeared in FreeBSD 13.0.