gpio-kbd-matrix

Vendor: Generic or vendor-independent

Description

GPIO based keyboard matrix input device

Implement an input device for a GPIO based keyboard matrix.

Example configuration:

kbd-matrix {
        compatible = "gpio-kbd-matrix";
        row-gpios = <&gpio0 0 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>,
                    <&gpio0 1 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
        col-gpios = <&gpio0 2 GPIO_ACTIVE_LOW>,
                    <&gpio0 3 GPIO_ACTIVE_LOW>,
                    <&gpio0 4 GPIO_ACTIVE_LOW>;
        no-ghostkey-check;
};

Properties

Properties not inherited from the base binding file.

Name

Type

Details

row-gpios

phandle-array

 
GPIO for the keyboard matrix rows, up to 8 different GPIOs. All row GPIO
pins must have interrupt support if idle-mode is set to "interrupt"
(default).

This property is required.

col-gpios

phandle-array

 
GPIO for the keyboard matrix columns, supports up to 32 different GPIOs.
When unselected, this pin will be either driven to inactive state or
configured to high impedance (input) depending on the col-drive-inactive
property.

This property is required.

col-drive-inactive

boolean

 
If enabled, unselected column GPIOs will be driven to inactive state.
Default to configure unselected column GPIOs to high impedance.

idle-mode

string

 
Controls the driver behavior on idle, "interrupt" waits for a new key
press using GPIO interrupts on the row lines, "poll"  periodically polls
the row lines with all the columns selected, "scan" just keep scanning
the matrix continuously, requires "poll-timeout-ms" to be set to 0.

Default value: interrupt

Legal values: 'interrupt', 'poll', 'scan'

poll-period-ms

int

 
Defines the poll period in msecs between between matrix scans, set to 0
to never exit poll mode. Defaults to 5ms if unspecified.

Default value: 5

poll-timeout-ms

int

 
How long to wait before going from polling back to idle state. Defaults
to 100ms if unspecified.

Default value: 100

debounce-down-ms

int

 
Debouncing time for a key press event. Defaults to 10ms if unspecified.

Default value: 10

debounce-up-ms

int

 
Debouncing time for a key release event. Defaults to 20ms if unspecified.

Default value: 20

settle-time-us

int

 
Delay between setting column output and reading the row values. Defaults
to 50us if unspecified.

Default value: 50

actual-key-mask

array

 
Keyboard scanning mask. For each keyboard column, specify which keyboard rows actually exist. Can be used to avoid triggering the ghost detection on non existing keys. No masking by default, any combination is valid.

no-ghostkey-check

boolean

 
Ignore the ghost key checking in the driver if the diodes are used
in the matrix hardware.