gpio-mmio-latch

Description

Memory-mapped latch GPIO controller

GPIO controller backed by a memory-mapped output latch register.

Each GPIO line corresponds to one bit in the latch register. Writing a bit
drives the associated output and the value remains latched until another
write updates it. The hardware is output-only and may not provide a readable
register, so the driver keeps a software shadow of the last output value to
implement GPIO masked writes, set, clear, toggle, and readback operations.

Examples

gpio_latch0: gpio@40000000 {
    compatible = "gpio-mmio-latch";
    reg = <0x40000000 0x4>;
    gpio-controller;
    #gpio-cells = <2>;
    ngpios = <8>;
    initial-output = <0x5a>;
};

Properties

Top level properties

These property descriptions apply to “gpio-mmio-latch” 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`	Number of usable GPIO lines exposed by this latch port. Must not exceed the register width in bits. This property is required. Default value: `32`
`initial-output`	`int`	Initial shadow/output value written to the latch during driver init. The default writes 0 to the latch so all output bits start cleared. Override this property if the board requires a different latch output pattern during initialization. Default value: `0`
`#gpio-cells`	`int`	Number of items to expect in a GPIO specifier This property is required. Constant value: `2`
`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

Properties inherited from the base binding file, which defines common properties that may be set on many nodes. Not all of these may apply to the “gpio-mmio-latch” compatible.

Name	Type	Details
`reg`	`array`	Information used to address the device. The value is specific to the device (i.e. is different depending on the compatible property). The "reg" property is typically a sequence of (address, length) pairs. Each pair is called a "register block". Values are conventionally written in hex. For details, see "2.3.6 reg" in Devicetree Specification v0.4. This property is required. See Important properties for more information.
`status`	`string`	Indicates the operational status of the hardware or other resource that the node represents. In particular: - "okay" means the resource is operational and, for example, can be used by device drivers - "disabled" means the resource is not operational and the system should treat it as if it is not present For details, see "2.3.4 status" in Devicetree Specification v0.4. Legal values: `okay`, `disabled`, `reserved`, `fail`, `fail-sss` See Important properties for more information.
`compatible`	`string-array`	This property is a list of strings that essentially define what type of hardware or other resource this devicetree node represents. Each device driver checks for specific compatible property values to find the devicetree nodes that represent resources that the driver should manage. The recommended format is "vendor,device", The "vendor" part is an abbreviated name of the vendor. The "device" is usually from the datasheet. The compatible property can have multiple values, ordered from most- to least-specific. Having additional values is useful when the device is a specific instance of a more general family, to allow the system to match the most specific driver available. For details, see "2.3.1 compatible" in Devicetree Specification v0.4. This property is required. See Important properties for more information.
`reg-names`	`string-array`	Optional names given to each register block in the "reg" property. For example: / { soc { #address-cells = <1>; #size-cells = <1>; uart@1000 { reg = <0x1000 0x2000>, <0x3000 0x4000>; reg-names = "foo", "bar"; }; }; }; The uart@1000 node has two register blocks: - one with base address 0x1000, size 0x2000, and name "foo" - another with base address 0x3000, size 0x4000, and name "bar"
`interrupts`	`array`	Information about interrupts generated by the device, encoded as an array of one or more interrupt specifiers. The format of the data in this property varies by where the device appears in the interrupt tree. Devices with the same "interrupt-parent" will use the same format in their interrupts properties. For details, see "2.4 Interrupts and Interrupt Mapping" in Devicetree Specification v0.4. See Important properties for more information.
`interrupts-extended`	`compound`	Extended interrupt specifier for device, used as an alternative to the "interrupts" property. For details, see "2.4 Interrupts and Interrupt Mapping" in Devicetree Specification v0.4.
`interrupt-names`	`string-array`	Optional names given to each interrupt generated by a device. The interrupts themselves are defined in either "interrupts" or "interrupts-extended" properties. For details, see "2.4 Interrupts and Interrupt Mapping" in Devicetree Specification v0.4.
`interrupt-parent`	`phandle`	If present, this refers to the node which handles interrupts generated by this device. For details, see "2.4 Interrupts and Interrupt Mapping" in Devicetree Specification v0.4.
`label`	`string`	Human readable string describing the device. Use of this property is deprecated except as needed on a case-by-case basis. For details, see "4.1.2 Miscellaneous Properties" in Devicetree Specification v0.4. See Important properties for more information.
`clocks`	`phandle-array`	Information about the device's clock providers. In general, this property should follow conventions established in the dt-schema binding: https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/clock/clock.yaml
`clock-names`	`string-array`	Optional names given to each clock provider in the "clocks" property.
`#address-cells`	`int`	This property encodes the number of <u32> cells used by address fields in "reg" properties in this node's children. For details, see "2.3.5 #address-cells and #size-cells" in Devicetree Specification v0.4.
`#size-cells`	`int`	This property encodes the number of <u32> cells used by size fields in "reg" properties in this node's children. For details, see "2.3.5 #address-cells and #size-cells" in Devicetree Specification v0.4.
`dma-coherent`	`boolean`	Indicates that the device is capable of coherent DMA operations. For details, see "2.3.10 dma-coherent" in Devicetree Specification v0.4.
`dmas`	`phandle-array`	DMA channel specifiers relevant to the device.
`dma-names`	`string-array`	Optional names given to the DMA channel specifiers in the "dmas" property.
`io-channels`	`phandle-array`	IO channel specifiers relevant to the device.
`io-channel-names`	`string-array`	Optional names given to the IO channel specifiers in the "io-channels" property.
`mboxes`	`phandle-array`	Mailbox / IPM channel specifiers relevant to the device.
`mbox-names`	`string-array`	Optional names given to the mbox specifiers in the "mboxes" property.
`power-domains`	`phandle-array`	Power domain specifiers relevant to the device.
`power-domain-names`	`string-array`	Optional names given to the power domain specifiers in the "power-domains" property.
`#power-domain-cells`	`int`	Number of cells in power-domains property
`hwlocks`	`phandle-array`	HW spinlock id relevant to the device.
`hwlock-names`	`string-array`	Optional names given to the hwlock specifiers in the "hwlocks" property.
`zephyr,deferred-init`	`boolean`	Do not initialize device automatically on boot. Device should be manually initialized using device_init().
`wakeup-source`	`boolean`	Property to identify that a device can be used as wake up source. When this property is provided a specific flag is set into the device that tells the system that the device is capable of wake up the system. Wake up capable devices are disabled (interruptions will not wake up the system) by default but they can be enabled at runtime if necessary.
`zephyr,pm-device-runtime-auto`	`boolean`	Automatically configure the device for runtime power management after the init function runs.
`zephyr,disabling-power-states`	`phandles`	List of power states that will disable this device power.

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