PCA954X(4)             FreeBSD Kernel Interfaces Manual             PCA954X(4)

NAME
     pca954x - driver for PCA9548A I2C switch

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

           device pca954x
           device iicmux
           device iicbus

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

           pca954x_load="YES"

DESCRIPTION
     The pca954x driver supports the PCA9548A I2C bus switch and compatible
     chips such as TCA9548A.  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 pca954x device node is defined as a child
     node of its upstream I2C bus.  The children of the pca954x node are
     additional I2C buses, which will have their own I2C slave devices
     described in their child nodes.

     The pca954x driver attaches to nodes where the compatible property is set
     to one of

     •   "nxp,pca9548"

     The pca954x driver supports the following optional properties in addition
     to the standard I2C mux properties:

     i2c-mux-idle-disconnect  if defined, forces the switch to disconnect all
                              children in idle state.

HINTS CONFIGURATION
     On a device.hints(5) based system, these values are configurable for
     pca954x:

     hint.pca954x.<unit>.at         The upstream iicbus(4) the pca954x
                                    instance is attached to.

     hint.pca954x.<unit>.chip_type  The type of the chip.  At present, only
                                    "pca9548" is supported.

     When configured via hints, the driver automatically adds an iicbus(4)
     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 pca954x driver and this manual page was written by Andriy Gapon
     <avg@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6        November 13, 2021       FreeBSD 13.1-RELEASE-p6