[PATCH v3 0/3] iio: adc: add support for the MAX34417 Four-Channel High Dynamic Range Power Accumulator

[Neil Armstrong]

The MAX34417 is a specialized current and voltage monitor used to
determine power consumption of portable systems. The driver supports
getting the channels voltage, average power and accumulated average
power and energy over an I2C/SMBUS serial interface.

The MAX34417 datasheet only specified on how to calculate the
accumulated average power, but with the Sample Per Second rate
we can easily get accumulated Energy in mJ.

By default the IIO driver only supports single-shot Voltage
and Power sensing, but the accumulation can be enabled by
enabling the Energy IIO channel which then enables the
Continuous Accumulation Mode.

The counter is common to all channels, so when reading a single
channel we will copy all accumulators to registers, so in order
to permit reading individual channels we must accumulate the
other channels in the driver when Continuous Accumulation Mode
is enabled.

The get_unaligned_be56() helper is added since we effectly
get an unaligned 56bit value from the HW.

While Maxim originally provided an HWMON driver for this
IC, using IIO makes much more sense because it provides
much more flexibility to support getting the power values
and will make it easier to support trigger to dump all
channels in a single shot and then support the Bulk Update
feature to update all MAX34417 on the same bus via the
trigger mechanism.

The v3 implementation has been completely revised since
v1/v2 to better match the capabilities of the MAX34417 and
allow getting accumulated Energy plus provide single
channel read without loosing other channels accumulations.

Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
---
Changes in v3:
- Implement Continuous Accumulate Mode and default to single-shot mode
- Fix includes
- Better define Rsense and default rsensd in driver & bindings
- Define all read length and offsets
- Define the SPS bits
- Fix comments first letters
- Fix max register
- Add ENERGY channel with shared enable for Continuous Accumulate Mode
- By default reset the MAX34417 counters for each readout to do a single-shot measure
- Handle zero counter
- Add get_unaligned_be56
- Use get_unaligned_* macros
- Better handle the DT properties and report errors
- Reset the MAX34417 at the end of probe
- Link to v2: https://patch.msgid.link/20260924-topic-sm8x50-iio-max34417-adc-v2-0-9a0609e72f5c@xxxxxxxxxx

Changes in v2:
- switch to shunt-resistor-micro-ohms no more required
- removed gpio.h from example
- Fixed max34417->MAX34417 in Kconfig and comments
- Added missing includes and remove unneeded
- Fixed typos in comments
- Switched to fsleep()
- Better aligned max34417_read_power declararation
- Handled 0 acc_count
- Switched to GENMASK_ULL() for 32bits systems
- Added missing empty lines
- Moved the input correction into a helper
- Set default input correction for all channels
- Switched to dev_err_probe() to return from probe
- Switched to device_for_each_child_node_scoped()
- Handled invalid shunt-resistor-micro-ohms value
- Link to v1: https://patch.msgid.link/20260923-topic-sm8x50-iio-max34417-adc-v1-0-41d4ba1bfc41@xxxxxxxxxx

To: Jonathan Cameron <jic23@xxxxxxxxxx>
To: David Lechner <dlechner@xxxxxxxxxxxx>
To: Nuno Sá <nuno.sa@xxxxxxxxxx>
To: Andy Shevchenko <andy@xxxxxxxxxx>
To: Rob Herring <robh@xxxxxxxxxx>
To: Krzysztof Kozlowski <krzk+dt@xxxxxxxxxx>
To: Conor Dooley <conor+dt@xxxxxxxxxx>
To: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
Cc: linux-iio@xxxxxxxxxxxxxxx
Cc: devicetree@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx

---
Marius Cristea (1):
      unaligned: introduce be56 unaligned accessors

Neil Armstrong (2):
      dt-bindings: iio: add: document the MAX34417 Four-Channel High Dynamic Range Power Accumulator
      iio: adc: add driver for the MAX34417 Four-Channel High Dynamic Range Power Accumulator

 .../bindings/iio/adc/maxim,max34417.yaml           | 100 +++
 drivers/iio/adc/Kconfig                            |  11 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/max34417.c                         | 777 +++++++++++++++++++++
 include/linux/unaligned.h                          |  27 +
 5 files changed, 916 insertions(+)
---
base-commit: fd73f4a6659897191fa0d40695fe370925dd3780
change-id: 20260923-topic-sm8x50-iio-max34417-adc-209e880533fb

Best regards,
--  
Neil Armstrong <neil.armstrong@xxxxxxxxxx>