This adds a new page to document how to use the ad4052 ADC driver. Signed-off-by: Jorge Marques <jorge.marques@xxxxxxxxxx> --- Documentation/iio/ad4052.rst | 95 ++++++++++++++++++++++++++++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 96 insertions(+) diff --git a/Documentation/iio/ad4052.rst b/Documentation/iio/ad4052.rst new file mode 100644 index 0000000000000000000000000000000000000000..410aaa437ed5fea6a2924d374fa5f816f5754e22 --- /dev/null +++ b/Documentation/iio/ad4052.rst @@ -0,0 +1,95 @@ +.. SPDX-License-Identifier: GPL-2.0-only + +============= +AD4052 driver +============= + +ADC driver for Analog Devices Inc. AD4052 and similar devices. +The module name is ``ad4052``. + +Supported devices +================= + +The following chips are supported by this driver: + +* `AD4050 <https://www.analog.com/AD4050>`_ +* `AD4052 <https://www.analog.com/AD4052>`_ +* `AD4056 <https://www.analog.com/AD4056>`_ +* `AD4058 <https://www.analog.com/AD4058>`_ + +Wiring modes +============ + +The ADC uses SPI 4-wire mode, and contain two programmable GPIOs and +a CNV pin. + +The CNV pin is exposed as the ``cnv-gpios`` and triggers a ADC conversion. +GP1 is ADC conversion ready signal and GP0 Threshold event interrupt, both +exposed as interrupts. + +Omit ``cnv-gpios`` and tie CNV and CS together to use the rising edge +of the CS as the CNV signal. + +Device attributes +================= + +The ADC contain only one channels, and the following attributes: + +.. list-table:: Driver attributes + :header-rows: 1 + + * - Attribute + - Description + * - ``in_voltage0_raw`` + - Raw ADC voltage value + * - ``in_voltage0_oversampling_ratio`` + - Enable the device's burst averaging mode to over sample using + the internal sample rate. + * - ``in_voltage0_oversampling_ratio_available`` + - List of available oversampling values. Value 0 disable the burst + averaging mode. + * - ``conversion_frequency`` + - Device internal sample rate used in the burst averaging mode. + * - ``conversion_frequency_available`` + - List of available sample rates. + +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 until +put back in configuration mode, due to this, the device returns busy until the +feature is disabled. + +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. + +SPI offload support +=================== + +To be able to achieve the maximum sample rate, the driver can be used with the +`AXI SPI Engine`_ to provide SPI offload support. + +.. _AXI SPI Engine: http://analogdevicesinc.github.io/hdl/projects/ad4052_ardz/index.html + +When SPI offload is being used, additional attributes are present: + +.. list-table:: Additional attributes + :header-rows: 1 + + * - Attribute + - Description + * - ``in_voltage0_sampling_frequency`` + - Set the sampling frequency. + * - ``in_voltage0_sampling_frequency_available`` + - Get the sampling frequency range. + +The scan type is different when the buffer with offload support is enabled. diff --git a/MAINTAINERS b/MAINTAINERS index 81fbe7176475c48eae03ab04115d4ef5b6299fac..04aa8db44bee418382a2e74cb6b1d03a810bd781 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1334,6 +1334,7 @@ M: Jorge Marques <jorge.marques@xxxxxxxxxx> S: Supported W: https://ez.analog.com/linux-software-drivers F: Documentation/devicetree/bindings/iio/adc/adi,ad4052.yaml +F: Documentation/iio/ad4052.rst ANALOG DEVICES INC AD4130 DRIVER M: Cosmin Tanislav <cosmin.tanislav@xxxxxxxxxx> -- 2.49.0
