[PATCH v6 0/3] Add driver for AD3530R and AD3531R DACs

[Kim Seer Paller <kimseer.paller@analog.com>]

The AD3530/AD3530R (8-channel) and AD3531/AD3531R (4-channel) are
low-power, 16-bit, buffered voltage output DACs with software-
programmable gain controls, providing full-scale output spans of 2.5V or
5V for reference voltages of 2.5V. These devices operate from a single
2.7V to 5.5V supply and are guaranteed monotonic by design. The "R"
variants include a 2.5V, 5ppm/°C internal reference, which is disabled
by default.

Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
---
Changes in v6:
ad3530r:
- Drop reviewer's tag, a re-review might be required due to changes.
- Add includes: dev_printk.h, array_size.h, sysfs.h, kstrtox.h, types.h,
  and err.h.
- Add AD3530R_OP_MODE_CHAN_MSK() macro to drop using chan->address.
- Update logic to explicitly set operating modes for all 4 fields of the
  register.
- Update naming to use _mV for proper spelling.
- Assign pdmode separately before shifting for powerdown.
- Replace U16_MAX with a hardware-defined limit using GENMASK().
- Replace hardcoded delays with USEC_PER_MSEC.
- Update `vref / 1000` to use MILLI.
- Simplify logic of setting vref to 0 when it's -ENODEV and directly
  check the value, removing the need for an additional boolean variable.

- Link to v5: https://lore.kernel.org/r/20250421-togreg-v5-0-94341574240f@analog.com

Changes in v5:
ad3530r:
- Replace return value to -ENODEV if no external and internal reference
  found.
- Replace device_property_present() with device_property_read_bool() for
  flag handling.
- Simplify vref_mv calculation by using range_multiplier directly.
- Change ldac GPIO initial state as it is toggled high to low later.
- Drop linux/kernel.h include.
- Add reviewer's tag.

- Link to v4: https://lore.kernel.org/r/20250412-togreg-v4-0-cb9e5309b99d@analog.com

Changes in v4:
Bindings:
- Add ad3531/ad3531r datasheet link.
- Add reviewer's tag.

ad3530r:
- Add commit description for unimplemented MUXOUT ADC monitoring feature.
- Use a DMA-safe buffer for bulk register read/write.
- Inline the AD3530R_CHAN_EXT_INFO macro for the "powerdown" attribute
  since it is only used once.
- Use enum ad3530r_mode for powerdown_mode.
- Refactor ad3530r_set_dac_powerdown() use chan->address for bitmask
  calculations and add helper variables.
- Simplify single-bit configuration with regmap_set_bits().
- Add .max_register for regmap_config.
- Rework regulator handling and move ad3530r_setup() after enabling the
  regulators.

- Link to v3: https://lore.kernel.org/r/20250403-togreg-v3-0-d4b06a4af5a9@analog.com

Changes in v3:
- Drop ABI docs.

Bindings:
- Drop reviewer's tag.
- Update commit message.
- Add non-r variants to compatible list.
- Add io-channels property to enable ADC channel support for MUXOUT
  readings.
- Switch to unevaluatedProperties: false.

ad3530r:
- Update commit message.
- Drop spi field from ad3530r_state and use regmap to retrieve the device
  pointer.
- Update mutex lock comment and use devm_mutex_init().
- Fix LDAC gpio pulse logic.
- Replace usleep_range() with fsleep().
- Use sizeof(reg_val) instead of hardcoded value in regmap_bulk_read.
- Drop reporting of zero offset.
- Add internal_ref_support chip_info parameter and modify reference
  handling.

- Link to v2: https://lore.kernel.org/r/20250324-togreg-v2-0-f211d781923e@analog.com

Changes in v2:
Bindings:
- Updated commit message.
- Changed adi,double-output-range to adi,range-double property.

ad3530r:
- Changed data type to __be16 to resolve sparse warnings related to
  type mismatches.

- Link to v1: https://lore.kernel.org/r/20250319-togreg-v1-0-d8244a502f2c@analog.com

---
Kim Seer Paller (3):
      iio: ABI: add new DAC powerdown mode
      dt-bindings: iio: dac: Add adi,ad3530r.yaml
      iio: dac: ad3530r: Add driver for AD3530R and AD3531R

 Documentation/ABI/testing/sysfs-bus-iio            |   2 +
 .../devicetree/bindings/iio/dac/adi,ad3530r.yaml   | 100 ++++
 MAINTAINERS                                        |   8 +
 drivers/iio/dac/Kconfig                            |  11 +
 drivers/iio/dac/Makefile                           |   1 +
 drivers/iio/dac/ad3530r.c                          | 515 +++++++++++++++++++++
 6 files changed, 637 insertions(+)
---
base-commit: b475195fecc79a1a6e7fb0846aaaab0a1a4cb2e6
change-id: 20250319-togreg-fc6a0af961ed

Best regards,
-- 
Kim Seer Paller <kimseer.paller@analog.com>