[PATCH v2 0/3] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam <shofiqtest@gmail.com>]

The MAX86150 (Maxim/Analog Devices) combines two PPG optical channels
(Red/IR LED) and one ECG biopotential channel in a single I2C device.
Data is produced at up to 3200 Hz and buffered in a 32-entry hardware
FIFO with a configurable almost-full interrupt.

This series adds:
  1. DT binding YAML schema for maxim,max86150
  2. IIO driver with triggered buffer support
  3. MAINTAINERS entry

Changes in v2 (addressing Sashiko AI review, Joshua Crofts, Krzysztof Kozlowski):
  - Fix buffer overflow: expand scan buffer to s32 buf[6] to hold
    3 x s32 channels + 4-byte pad + s64 timestamp (24 bytes total)
  - Add iio_device_claim_direct() in read_raw to prevent concurrent
    sysfs reads from corrupting FIFO pointers during buffer capture
  - Fix FIFO-full detection: read OVF_COUNTER to distinguish a fully
    saturated FIFO (wr_ptr == rd_ptr after wrap) from an empty one
  - Fix active_scan_mask handling: pack only active channels at
    consecutive positions using test_bit(idx, active_scan_mask)
  - Remove IRQF_ONESHOT from IRQ request (not needed for edge-triggered;
    iio_trigger_generic_data_rdy_poll is a hard-IRQ handler)
  - Add set_trigger_state callback to enable/disable A_FULL interrupt
    only when the IIO buffer is active, preventing the interrupt line
    from asserting before the handler is registered
  - Fix endianness: change scan_type.endianness from IIO_LE to IIO_CPU
    to match native integers written directly into the buffer
  - Add max86150_powerdown() devm action to disable interrupts and
    assert SYS_SHDN on driver unload
  - Add devm_regulator_get_enable() for vdd-supply and leds-supply
    before any I2C access
  - Add devm action for iio_trigger_put() to balance the reference
    count increment from iio_trigger_get()
  - Split DT binding into a separate first patch (requested by Joshua Crofts)
  - Add MAINTAINERS entry (requested by Joshua Crofts)

Known limitations (to be addressed in v3):
  - IIO_CHAN_INFO_SCALE not yet implemented
  - Runtime PM (SYS_CTRL SHDN bit) not yet implemented
  - Not yet tested on physical hardware

Md Shofiqul Islam (3):
  dt-bindings: iio: health: add maxim,max86150
  iio: health: add MAX86150 ECG and PPG biosensor driver
  MAINTAINERS: add entry for MAX86150 IIO health driver

 .../bindings/iio/health/maxim,max86150.yaml   |  67 ++
 MAINTAINERS                                   |   7 +
 drivers/iio/health/Kconfig                    |  18 +
 drivers/iio/health/Makefile                   |   1 +
 drivers/iio/health/max86150.c                 | 612 ++++++++++++++++++
 5 files changed, 705 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
 create mode 100644 drivers/iio/health/max86150.c

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2.51.1