mcpgpio(4) - NetBSD Manual Pages

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MCPGPIO(4)              NetBSD 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 inter-
     nal 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 attach-
     ment.


AUTHORS

     The mcpgpio driver was written by Frank Kardel <kardel@NetBSD.org> and
     Jason R. Thorpe <thorpej@NetBSD.org>.


BUGS

     SPI instances of the mcpgpio driver do not utilize the Device Tree bind-
     ings for this device.

     The mcpgpio driver does not currently act as a GPIO provider for the
     platform device tree.

NetBSD 10.99                   January 10, 2022                   NetBSD 10.99