AD4062 driver

ADC driver for Analog Devices Inc. AD4060/AD4062 devices. The module name is ad4062.

Supported devices

The following chips are supported by this driver:

• AD4060

• AD4062

Wiring modes

The ADC is interfaced through an I3C bus, and contains two programmable GPIOs.

The ADC convert-start happens on the SDA rising edge of the I3C stop (P) bit at the end of the read command.

The two programmable GPIOS are optional and have a role assigned if present in the devicetree interrupt-names property:

• GP0: Is assigned the role of Threshold Either signal.

• GP1: Is assigned the role of Data Ready signal.

If the property gpio-controller is present in the devicetree, then the GPO not present in the interrupt-names is exposed as a GPO.

Device attributes

The ADC contains only one channel with following attributes:

Channel attributes

Attribute	Description
in_voltage_calibscale	Sets the gain scaling factor that the hardware applies to the sample, to compensate for system gain error.
in_voltage_oversampling_ratio	Sets device’s burst averaging mode to over sample using the internal sample rate. Value 1 disable the burst averaging mode.
in_voltage_oversampling_ratio_available	List of available oversampling values.
in_voltage_raw	Returns the raw ADC voltage value.
in_voltage_scale	Returns the channel scale in reference to the reference voltage ref-supply or vdd-supply if the former not present.

Also contain the following device attributes:

Device attributes

Attribute	Description
sampling_frequency	Sets the duration of a single scan, used in the burst averaging mode. The duration is described by (n_avg - 1) / fosc + tconv, where n_avg is the oversampling ratio, fosc is the internal sample rate and tconv is the ADC conversion time.
sampling_frequency_available	Lists the available sampling frequencies, computed on the current oversampling ratio. If the ratio is 1, the frequency is 1/tconv.

Interrupts

The interrupts are mapped through the interrupt-names and interrupts properties.

The interrupt-names gp0 entry sets the role of Threshold signal, and entry gp1 the role of Data Ready signal.

If each is not present, the driver fallback to enabling the same role as an I3C IBI.

Low-power mode

The device enters low-power mode on idle to save power. Enabling an event puts the device out of the low-power since the ADC autonomously samples to assert the event condition.

IIO trigger support

An IIO trigger ad4062-devX is registered by the driver to be used by the same device, to capture samples to a software buffer. It is required to attach the trigger to the device by setting the current_trigger before enabling and reading the buffer.

The acquisition is sequential and bounded by the protocol timings, software latency and internal timings, the sample rate is not configurable. The burst averaging mode does impact the effective sample rate, since it increases the internal timing to output a single sample.

Threshold events

The ADC supports a monitoring mode to raise threshold events. The driver supports a single interrupt for both rising and falling readings.

The feature is enabled/disabled by setting thresh_either_en. During monitor mode, the device continuously operates in autonomous mode. Any register access puts the device back in configuration mode, due to this, any access disables monitor mode.

The following event attributes are available:

Event attributes

Attribute	Description
sampling_frequency	Frequency used in the monitoring mode, sets the device internal sample rate when the mode is activated.
sampling_frequency_available	List of available sample rates.
thresh_either_en	Enable monitoring mode.
thresh_falling_hysteresis	Set the hysteresis value for the minimum threshold.
thresh_falling_value	Set the minimum threshold value.
thresh_rising_hysteresis	Set the hysteresis value for the maximum threshold.
thresh_rising_value	Set the maximum threshold value.

GPO controller support

The device supports using GP0 and GP1 as GPOs. If the devicetree contains the node gpio-controller`, the device is marked as a GPIO controller and the GPs not listed in interrupt-names are exposed as a GPO. The GPIO index matches the pin name, so if GP0 is not exposed but GP1 is, index 0 is masked out and only index 1 can be set.