This adds a new page to document how to use the ad4030 ADC driver Signed-off-by: Esteban Blanc <eblanc@xxxxxxxxxxxx> --- Documentation/iio/ad4030.rst | 129 +++++++++++++++++++++++++++++++++++++++++++ Documentation/iio/index.rst | 1 + MAINTAINERS | 1 + 3 files changed, 131 insertions(+) diff --git a/Documentation/iio/ad4030.rst b/Documentation/iio/ad4030.rst new file mode 100644 index 000000000000..56e0ba58b127 --- /dev/null +++ b/Documentation/iio/ad4030.rst @@ -0,0 +1,129 @@ +.. SPDX-License-Identifier: GPL-2.0-only + +============= +AD4030 driver +============= + +ADC driver for Analog Devices Inc. AD4030 and similar devices. The module name +is ``ad4030``. + + +Supported devices +================= + +The following chips are supported by this driver: + +* `AD4030-24 <https://www.analog.com/AD4030-24>`_ +* `AD4630-16 <https://www.analog.com/AD4630-16>`_ +* `AD4630-24 <https://www.analog.com/AD4630-24>`_ +* `AD4632-16 <https://www.analog.com/AD4632-16>`_ +* `AD4632-24 <https://www.analog.com/AD4632-24>`_ + +IIO channels +============ + +Each "device" channel as described in the datasheet is split in 2 IIO channels, +in the following order: + +- One channel for the differential data +- One channel for the common byte. + +Supported features +================== + +SPI wiring modes +---------------- + +The driver currently supports the following SPI wiring configurations: + +One lane mode +^^^^^^^^^^^^^ + +In this mode, each channel has its own SDO line to send the conversion results. +At the moment this mode can only be used on AD4030 which has one channel so only +one SDO line is used. + +.. code-block:: + + +-------------+ +-------------+ + | ADC | | HOST | + | | | | + | CNV |<--------| CNV | + | CS |<--------| CS | + | SDI |<--------| SDO | + | SDO0 |-------->| SDI | + | SCLK |<--------| SCLK | + +-------------+ +-------------+ + +Interleaved mode +^^^^^^^^^^^^^^^^ + +In this mode, both channels conversion results are bit interleaved one SDO line. +As such the wiring is the same as `One lane mode`. + +SPI Clock mode +-------------- + +Only the SPI clocking mode is supported. + +Output modes +------------ + +There is more exposed IIO channels than channels as describe in the devices +datasheet. This is due to the `Differential data + 8-bit common-mode` encoding +2 types of information in one conversion result. As such a "device" channel +provides 2 IIO channels, one for the differential data and one for the common +byte. + +Differential data +^^^^^^^^^^^^^^^^^ + +This mode is selected when: + +- Only differential channels are selected +- Oversampling attribute is set to 1 + +Differential data + common-mode +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +This mode is selected when: + +- Differential and common-mode channels are selected +- Oversampling attribute is set to 1 + +For the 24-bits chips, this mode is also available with 16-bits differential +data but is not selectable yet. + +Averaged differential data +^^^^^^^^^^^^^^^^^^^^^^^^^^ + +This mode is selected when: + +- Only differential channels are selected +- Oversampling attribute is greater than 1 + +Reference voltage +----------------- + +The chip supports an external reference voltage via the ``REF`` input or an +internal buffered reference voltage via the ``REFIN`` input. The driver looks +at the device tree to determine which is being used. If ``ref-supply`` is +present, then the external reference voltage is used and the internal buffer is +disabled. If ``refin-supply`` is present, then the internal buffered reference +voltage is used. + +Reset +----- + +Both hardware and software reset are supported. The driver looks first at the +device tree to see if the `reset-gpio` is populated. If not present, the driver +will fallback to a software reset by wiring to the device's registers. + +Unimplemented features +---------------------- + +- ``BUSY`` indication +- Additional wiring modes +- Additional clock modes +- Differential data 16-bits + common-mode for 24-bits chips + diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst index dfcf9618568a..61faf3a60da6 100644 --- a/Documentation/iio/index.rst +++ b/Documentation/iio/index.rst @@ -19,6 +19,7 @@ Industrial I/O Kernel Drivers :maxdepth: 1 ad4000 + ad4030 ad4695 ad7380 ad7944 diff --git a/MAINTAINERS b/MAINTAINERS index 6a5a0e7b7a51..4a076a48648a 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -420,6 +420,7 @@ R: Esteban Blanc <eblanc@xxxxxxxxxxxx> S: Supported W: https://ez.analog.com/linux-software-drivers F: Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml +F: Documentation/iio/ad4030.c F: drivers/iio/adc/ad4030.c AD5110 ANALOG DEVICES DIGITAL POTENTIOMETERS DRIVER -- 2.44.1
