[v4,0/6] Add support for AD411x

Message

Dumitru Ceclan via B4 Relay May 31, 2024, 7:42 p.m. UTC

This patch series adds support for the Analog Devices AD4111, AD4112,
 AD4114, AD4115, AD4116 within the existing AD7173 driver.

  The AD411X family encompasses a series of low power, low noise, 24-bit,
sigma-delta analog-to-digital converters that offer a versatile range of
specifications. They integrate an analog front end suitable for processing
fully differential/single-ended and bipolar voltage inputs.

Particularities of the models:
- All ADCs have inputs with a precision voltage divider with a division
ratio of 10.
- AD4116 has 5 low level inputs without a voltage divider.
- AD4111 and AD4112 support current inputs (0 mA to 20 mA) using a 50ohm
shunt resistor.

Discussions from this patch series have concluded with:
-Datasheets mention single-ended and pseudo differential capabilities by
 the means of connecting the negative input of a differential pair (IN-)
 to a constant voltage supply and letting the positive input fluctuate.
 This is not a special operating mode, it is a capability of the
 differential channels to also measure such signals.

-Single-ended and pseudo differential do not need any specific
 configuration and cannot be differentiated from differential usage by
 the driver side =>
	offer adi,channel-type attribute to flag the usage of the channel

-VINCOM is described as a dedicated pin for single-ended channels but as
 seen in AD4116, it is a normal input connected to the cross-point
 multiplexer (VIN10, VINCOM (single-ended or differential pair)).
 This does not mean full functionality in any configuration:
 AD4111:"If any two voltage inputs are paired in a configuration other
 than what is described in this data sheet, the accuracy of the device
 cannot be guaranteed".

-ADCIN15 input pin from AD4116 is specified as the dedicated pin for
 pseudo-differential but from the datasheet it results that this pin is
 also able to measure single-ended and fully differential channels
 ("ADCIN11, ADCIN15. (pseudo differential or differential pair)";
  "An example is to connect the ADCIN15 pin externally to the AVSS
   pin in a single-ended configuration")

 As such, detecting the type of usage of a channel is not possible and
will be the responsibility of the user to specify.
 If the user has connected a non 0V (in regards to AVSS) supply to
the negative input pin of a channel in a pseudo differential
configuration, the offset of the measurement from AVSS will not be known
from the driver and will need to be measured by other means.

Datasheets:
https://www.analog.com/media/en/technical-documentation/data-sheets/AD4111.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/AD4112.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/AD4114.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/AD4115.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/AD4116.pdf

This series depends on patches:
(iio: adc: ad7173: Use device_for_each_child_node_scoped() to simplify error paths.)
https://lore.kernel.org/all/[e-mail]
(dt-bindings: iio: adc: Add single-channel property)
https://lore.kernel.org/linux-iio/[e-mail]/

And patch series:
(AD7173 fixes)
https://lore.kernel.org/all/[e-mail]/

Signed-off-by: Dumitru Ceclan <[e-mail]>
---
Changes in v4:
dt-bindings: adc: ad7173: add support for ad411x
- remove "adi,channel-type"
- add "adi,common-mode-input" and "adi,current-channel" to use
  single-channel with both single-ended/pseudo-differential and current
  channels
- add restrictions to patternProperties channel to restrict presence of
  both diff-channels and single-channel
   and
  both "adi,current-channel" and "adi,common-mode-input"
- update diff-channels description
- update commit message to current state of the binding
- add a second example to exemplify single-ended and current channels

iio: adc: ad7173: refactor channel configuration parsing
- picked up reviewed-by tag

iio: adc: ad7173: refactor ain and vref selection
- Moved reference error message from validate_reference() to
  ad7173_get_ref_voltage_milli()
- Changed from dev_err_probe to dev_err as function can be reached from
  non probe paths
- added AD7173_NO_AINS_PER_CHANNEL to remove ambiguity when using the
  size of the ain array

iio: adc: ad7173: add support for special inputs
- picked up reviewed-by tag

iio: adc: ad7173: refactor device info structs
- create patch

iio: adc: ad7173: Add support for AD411x devices
- separate chip id defines for ad411<1,2,4>
- fix device_info typos: voltage, VINCOM
- rename num_voltage_inputs and num_voltage_inputs_with_divider to *_voltage_in*
- subtract ch->cfg.bipolar directly
- change to const ain argument in *_validate_current_ain()
- change parsing to new dt structure for current and single-ended channels
- drop adi,channel-type
- refactor device info structs as the previous patch

iio: adc: ad7173: Reduce device info struct size
- remove patch as suggested by David Lechner as it would increase binary
  size more than the savings done in RAM

- Link to v3: https://lore.kernel.org/r/[e-mail]

Changes in v3:

iio: adc: ad7173: fix buffers enablement for ad7176-2
iio: adc: ad7173: Add ad7173_device_info names
iio: adc: ad7173: Remove index from temp channel
- Remove patches, send in separate series

dt-bindings: adc: ad7173: add support for ad411x
- fix VINCOM typo
- switch current channel definition to use single-channel
- remove pseudo-differential from adi,channel-type, specify that
  single-ended will be used for that case as well
- remove diff-channels from required, already defined in adc.yaml
- update constraints to not permit single-channel for models without
  current inputs

iio: adc: ad7173: refactor channel configuration parsing
- remove blank line from commit message

iio: adc: ad7173: refactor ain and vref selection
- remove blank space from commit message

iio: adc: ad7173: add support for special inputs
<no changes>

iio: adc: ad7173: Add support for AD411x devices
- remove pseudo diff channel type
- change current channels dt parsing to single-channel
- change module description from wild-card to "and similar"
- add comment to document HW behavior when multiple channels are enabled
  in buffered reading mode

iio: adc: ad7173: Reduce device info struct size
<no changes>

- Link to v2: https://lore.kernel.org/r/[e-mail]

Changes in v2:

dt-bindings: adc: ad7173: add support for ad411x
- Add constraint for missing avdd2-supply on ad411x
- Change support for current channels to selecting the actual
   diff-channels input values and activating the
   adi,current-channel property
- Add constraint for adi,current-channel
- Add adi,channel-type to be able to differentiante in the driver
   between single-ended, pseudo-differential and differential channels.
- Update diff-channels description to decribe inputs beside the AINs

iio: adc: ad7173: fix buffers enablement for ad7176-2
- Specify ".has_input_buf = false" for AD7176-2
- Drop fixes tag, specify that configuration bits are read only

iio: adc: ad7173: refactor channel configuration parsing
- Add Link and Suggested-by in commit message

iio: adc: ad7173: refactor ain and vref selection
- Improve commit message to express commit purpose
- Refactor line wrappings due to reduced indent
- Change AINs check to a loop

iio: adc: ad7173: add support for special inputs
- Create patch

iio: adc: ad7173: Add ad7173_device_info names
- Create patch

iio: adc: ad7173: Remove index from temp channel
- Justify in commit message userspace breakage
- Remove index from the correct channel template

iio: adc: ad7173: Add support for AD411x devices
- Add missing validation for VCOM and inputs with voltage divider
- Add missing validation for AD4116 low level inputs
- Add missing ad7173_device_info names
- Add support for setting differential flag depending on the channel type
- Change current channel validation to use actual pin values
- Combine multiple chipID reg values in a single define
		(AD7173_AD4111_AD4112_AD4114_ID)
- Rename num_inputs and num_inputs_with_divider to include voltage
- Add comment to specify that num_voltage_inputs_with_divider does not
   include the VCOM pin.
- Change break to direct returns where possible in switch cases
- Add fix for ad411x gpio's

iio: adc: ad7173: Reduce device info struct size
- Create patch

- Link to v1: https://lore.kernel.org/r/[e-mail]

---
Dumitru Ceclan (6):
      dt-bindings: adc: ad7173: add support for ad411x
      iio: adc: ad7173: refactor channel configuration parsing
      iio: adc: ad7173: refactor ain and vref selection
      iio: adc: ad7173: add support for special inputs
      iio: adc: ad7173: refactor device info structs
      iio: adc: ad7173: Add support for AD411x devices

 .../devicetree/bindings/iio/adc/adi,ad7173.yaml    | 192 +++++-
 drivers/iio/adc/ad7173.c                           | 682 +++++++++++++++------
 2 files changed, 691 insertions(+), 183 deletions(-)
---
base-commit: 02b664413a44903ef349bb70a3f1842cbcee9616
change-id: 20240312-ad4111-7eeb34eb4a5f

Best regards,