nxp,pcf8574 (on i2c bus)

Vendor: NXP Semiconductors

Description

PCF8574 8-bit I2C-based I/O expander

Properties

Top level properties

These property descriptions apply to “nxp,pcf8574” nodes themselves. This page also describes child node properties in the following sections.

Properties not inherited from the base binding file.

Name

Type

Details

ngpios

int

This property indicates the number of in-use slots of available slots
for GPIOs. The typical example is something like this: the hardware
register is 32 bits wide, but only 18 of the bits have a physical
counterpart. The driver is generally written so that all 32 bits can
be used, but the IP block is reused in a lot of designs, some using
all 32 bits, some using 18 and some using 12. In this case, setting
"ngpios = <18>;" informs the driver that only the first 18 GPIOs, at
local offset 0 .. 17, are in use.  For cases in which there might be
holes in the slot range, this value should be the max slot number+1.

This property is required.

Default value: 32

Constant value: 8

int-gpios

phandle-array

GPIO connected to the controller INT pin. This pin is active-low.

#gpio-cells

int

Number of items to expect in a GPIO specifier

This property is required.

Constant value: 2

supply-gpios

phandle-array

GPIO specifier that controls power to the device.

This property should be provided when the device has a dedicated
switch that controls power to the device.  The supply state is
entirely the responsibility of the device driver.

Contrast with vin-supply.

vin-supply

phandle

Reference to the regulator that controls power to the device.
The referenced devicetree node must have a regulator compatible.

This property should be provided when device power is supplied
by a shared regulator.  The supply state is dependent on the
request status of all devices fed by the regulator.

Contrast with supply-gpios.  If both properties are provided
then the regulator must be requested before the supply GPIOS is
set to an active state, and the supply GPIOS must be set to an
inactive state before releasing the regulator.

gpio-controller

boolean

Convey's this node is a GPIO controller

This property is required.

gpio-reserved-ranges

array

If not all the GPIOs at offsets 0...N-1 are usable for ngpios = <N>, then
this property contains an additional set of tuples which specify which GPIOs
are unusable. This property indicates the start and size of the GPIOs
that can't be used.

For example, setting "gpio-reserved-ranges = <3 2>, <10 1>;" means that
GPIO offsets 3, 4, and 10 are not usable, even if ngpios = <18>.

gpio-line-names

string-array

This is an array of strings defining the names of the GPIO lines
going out of the GPIO controller

Child node properties

Name

Type

Details

gpio-hog

boolean

Conveys this node is a GPIO hog.

This property is required.

gpios

array

This is an array of GPIO specifiers (e.g. pin, flags) to be hogged. The number of array
entries must be an integer multiple of the number of GPIO specifier cells for the parent
GPIO controller.

This property is required.

input

boolean

If this property is set, the GPIO is configured as an input. This property takes
precedence over the output-low and output-high properties.

output-low

boolean

If this property is set, the GPIO is configured as an output set to logical low. This
property takes precedence over the output-high property.

output-high

boolean

If this property is set, the GPIO is configured as an output set to logical high.

line-name

string

Optional GPIO line name.

Specifier cell names

  • gpio cells: pin, flags