iio: adc: add Nuvoton NCT7201 ADC driver

Change since version 10:
- Fix comments
- Add interrupt handler function to call iio_push_event()

Change since version 9:
- Fix comments
- Change vin_mask and mask from CPU-endian to little-endian
- Fix access to restricted __le16

Change since version 8:
- dev_err_probe(), move the definition from device.h to dev_printk.h
- Use USEC_PER_MSEC rather than the hard coded value of 1000
- Use one dev for both regmap and regmap16

Change since version 7:
- Fix comments
- Derive dev from the respective regmap
- Generate the mask from the number of voltage input channels

Change since version 6:
- Fix comments
- Add use_single_read in regmap_config
- Remove unused definitions
- Do not shadow the return code by -EIO and let regmap API caller to decide
- Use simple English in all error messages
- Use a local variable for the struct device pointers. This increases code readability with shortened lines.
- Use fsleep instead of mdelay
- Use 16 bits type __le16 instead of u8 data[2]

Change since version 5:
- Fix comments
- Add NUVOTON NCT7201 IIO DRIVER section in MAINTAINERS
- Add vdd-supply and vref-supply to the DT example
- Remove mutex since the regmap should already have an internal lock
- Remove redundant assigning values
- Check errors on regmap_write

Change since version 4:
- Fix comments
- Add interrupts and reset-gpios to the DT example
- Use the FIELD_PREP and FIELD_GET
- Add use_single_write in regmap_config
- Use regmap_access_table

Change since version 3:
- Fix comments
- Don't put nct720"x" in the name, just call it nct7201
- Remove differential inputs until conversions are finished
- Add NCT7201_ prefix in all macros and avoid the tables
- Correct event threshold values in raw units
- Add with and without interrupt callback function to have the event config part and one that doesn't
- Remove print an error message if regmap_wirte failed case

Change since version 2:
- Remvoe read-vin-data-size property, default use read word vin data
- Use regmap instead of i2c smbus API
- IIO should be IIO_CHAN_INFO_RAW and _SCALE not _PROCESSED
- Use dev_xxx_probe in probe function and dev_xxx in other functions
- Use devm_iio_device_register replace of iio_device_register
- Use guard(mutex) replace of mutex_lock
- Use get_unaligned_le16 conversion API

Changes since version 1:
- Add new property in iio:adc binding document
- Add new driver for Nuvoton NCT720x driver

Eason Yang (2):
dt-bindings: iio: adc: add NCT7201 ADCs
iio: adc: add support for Nuvoton NCT7201

 .../bindings/iio/adc/nuvoton,nct7201.yaml     |  70 +++
 MAINTAINERS                                   |   7 +
 drivers/iio/adc/Kconfig                       |  11 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/nct7201.c                     | 501 ++++++++++++++++++
 5 files changed, 590 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/nuvoton,nct7201.yaml
 create mode 100644 drivers/iio/adc/nct7201.c

2.34.1