[PATCH v7 0/9] Add support for AD411x

From: Dumitru Ceclan via B4 Relay
Date: Fri Jun 07 2024 - 10:58:20 EST

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/20240330190849.1321065-6-jic23@xxxxxxxxxx
(dt-bindings: iio: adc: Add single-channel property)
https://lore.kernel.org/linux-iio/20240514120222.56488-5-alisa.roman@xxxxxxxxxx/

And patch series:
(AD7173 fixes)
https://lore.kernel.org/all/20240521-ad7173-fixes-v1-0-8161cc7f3ad1@xxxxxxxxxx/

Signed-off-by: Dumitru Ceclan <mitrutzceclan@xxxxxxxxx>
---
Changes in v7:
dt-bindings: iio: adc: Add common-mode-channel property
dt-bindings: adc: ad7173: add support for ad411x
- pick up rb tag
iio: adc: ad_sigma_delta: add disable_one callback
- pick up rb tag
iio: adc: ad7173: refactor channel configuration parsing
iio: adc: ad7173: refactor ain and vref selection
- revert back to error message in validate_reference()
iio: adc: ad7173: add support for special inputs
- drop setting device_info flags to false
iio: adc: ad7173: refactor device info structs
- pick up rb tag
- remove set flags to false from device_info structs
iio: adc: ad7173: document sampling frequency behaviour
- pick up rb tag
iio: adc: ad7173: Add support for AD411x devices
- drop setting device_info flags to false
- give better error message for VINCOM input validation for models that
do not support it (this cannot be solved by checking ain == VINCOM
at the start of the function because the value 0x10 is valid for models
AD7173-8 and AD7175-8: AIN16)
- move VINCOM mismatch check at the end; stop checking for VINCOM
support as already checked before

- Link to v6: https://lore.kernel.org/r/20240606-ad4111-v6-0-573981fb3e2e@xxxxxxxxxx

Changes in v6:
dt-bindings: iio: adc: Add common-mode-channel property
- pick up rb tag

dt-bindings: adc: ad7173: add support for ad411x
- use ref flag instead of type: boolean
- document (AVDD-AVSS)/5 as a power supply monitoring option

iio: adc: ad_sigma_delta: add disable_one callback
iio: adc: ad7173: refactor channel configuration parsing
iio: adc: ad7173: refactor ain and vref selection
<no changes>

iio: adc: ad7173: add support for special inputs
- rename (AVDD-AVSS)/5 from common input to pow_mon
- restrict (AVDD-AVSS)/5 to only be correctly paired as
(AVDD-AVSS)/5+ 0 to ain0 (AVSS-AVDD)/5- to ain1

iio: adc: ad7173: refactor device info structs
- add space before '}' in device tables

iio: adc: ad7173: document sampling frequency behaviour
<no changes>

iio: adc: ad7173: Add support for AD411x devices
- fix typo
- drop current channels enum
- describe channel inputs array with comments
- check for vincom input support when setting special_input
- use fwnode_property_read_u32 instead of array for single value reads
- drop remnant of previous version is_current_chan value setting
- set ain value directly for current channels
- add space before '}' in device tables

- Link to v5: https://lore.kernel.org/r/20240603-ad4111-v5-0-9a9c54d9ac78@xxxxxxxxxx

Changes in v5:
dt-bindings: iio: adc: Add common-mode-channel property
- create patch

dt-bindings: adc: ad7173: add support for ad411x
- remove "adi" from common-mode-channel property

iio: adc: ad_sigma_delta: add disable_one callback
- create patch

iio: adc: ad7173: refactor channel configuration parsing
<no changes>

iio: adc: ad7173: refactor ain and vref selection
- change function header to send ain[0] and ain[1] as two arguments
- drop loop
- drop reviewed-by tag

iio: adc: ad7173: add support for special inputs
- unroll the loop in the ain validation function
- drop reviewed-by tag

iio: adc: ad7173: refactor device info structs
<no changes>

iio: adc: ad7173: document sampling frequency behaviour
- create patch

iio: adc: ad7173: Add support for AD411x devices
- rename VINCOM define from wildcard to specific models
- sampling frequency comment: "to" -> "for"
- don't set ain[1] for a second time in channel_parse, set
chan->channel2 value directly if the channel is a current channel
- revert white space change in channel config parse
- unroll the loop in the ain validation function
- use new common-mode-channel property name
- remove sampling frequency comment as included in a previous patch

- Link to v4: https://lore.kernel.org/r/20240531-ad4111-v4-0-64607301c057@xxxxxxxxxx

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/20240527-ad4111-v3-0-7e9eddbbd3eb@xxxxxxxxxx

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/20240514-ad4111-v2-0-29be6a55efb5@xxxxxxxxxx

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/20240401-ad4111-v1-0-34618a9cc502@xxxxxxxxxx

---
Dumitru Ceclan (9):
dt-bindings: iio: adc: Add common-mode-channel property
dt-bindings: adc: ad7173: add support for ad411x
iio: adc: ad_sigma_delta: add disable_one callback
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: document sampling frequency behaviour
iio: adc: ad7173: Add support for AD411x devices

Documentation/devicetree/bindings/iio/adc/adc.yaml | 11 +
.../devicetree/bindings/iio/adc/adi,ad7173.yaml | 194 +++++-
drivers/iio/adc/ad7124.c | 14 +-
drivers/iio/adc/ad7173.c | 674 +++++++++++++++------
drivers/iio/adc/ad_sigma_delta.c | 6 +
include/linux/iio/adc/ad_sigma_delta.h | 14 +
6 files changed, 719 insertions(+), 194 deletions(-)
---
base-commit: 02b664413a44903ef349bb70a3f1842cbcee9616
change-id: 20240312-ad4111-7eeb34eb4a5f

Best regards,
--
Dumitru Ceclan <dumitru.ceclan@xxxxxxxxxx>