MCPGPIO(4) FreeBSD Kernel Interfaces Manual MCPGPIO(4)
NAME
mcpgpio - Driver for Microchip I/O Expanders on I2C and SPI bus
SYNOPSIS
I2C
mcpgpio* at iic? addr ?
gpio* at gpiobus?
SPI
mcpgpio0 at spi? slave 0 flags 0
mcpgpio1 at spi? slave 0 flags 1
mcpgpio2 at spi? slave 0 flags 2
mcpgpio3 at spi? slave 0 flags 3
gpio* at gpiobus?
DESCRIPTION
The mcpgpio driver supports the following Microchip I/O Expanders:
MCP23008 8-bit I/O expander, I2C interface
MCP23S08 8-bit I/O expander, SPI interface
MCP23017 16-bit I/O expander, I2C interface
MCP23S17 16-bit I/O expander, SPI interface
MCP23018 16-bit I/O expander, open-drain outputs, I2C interface
MCP23S18 16-bit I/O expander, open-drain outputs, SPI interface
Access to the pins is provided by the gpio(4) interface.
The SPI version of these devices support multiple chips per chip select
signal. On the MCP23S08 and MCP23S17, this is achieved by tying the
address select pins to VDD or GND to select an address (0-3 on MCP23S08
or 0-7 on MCP23S17). The MCP23S18 has a similar capability, but uses an
analog voltage input on a single address select pin, along with an
internal voltage divider ladder and a series of comparators to generate
the 3 address bits; see the data sheet for details. The flags argument
in the configuration directive for SPI attachments selects the hardware
address of the chip instance for that driver instance.
SEE ALSO
gpio(4), iic(4), intro(4), spi(4)
HISTORY
The mcpgpio driver first appeared in NetBSD 7.0. It was overhauled in
NetBSD 10.0 to support additional chip types and to add the I2C
attachment.
AUTHORS
The mcpgpio driver was written by Frank Kardel <
[email protected]> and
Jason R. Thorpe <
[email protected]>.
BUGS
SPI instances of the mcpgpio driver do not utilize the Device Tree
bindings for this device.
The mcpgpio driver does not currently act as a GPIO provider for the
platform device tree.
FreeBSD 14.1-RELEASE-p8 January 10, 2022 FreeBSD 14.1-RELEASE-p8