[RFC PATCH 0/3] iio: proximity: Add Cytron HC-SR04 support

["Paweł Wiśniewski" <pawel.wis.me@gmail.com>]

Add Device Tree binding and driver match support for the Cytron
HC-SR04 ultrasonic distance sensor.

The HC-SR04 uses separate trigger and echo GPIOs. A trigger pulse of
at least 10 us starts a measurement, and the echo pulse width reports
the ultrasonic round-trip time. This matches the protocol already
implemented by the SRF04 IIO driver.

The series adds the Cytron vendor prefix, documents the
cytron,hc-sr04 compatible, and uses the existing SRF04 configuration
in the driver.

The Cytron vendor attribution is based on the HC-SR04 Product User's
Manual V1.0 supplied by the retailer. The manual was prepared by
Cytron Technologies Sdn. Bhd. and contains Cytron warranty and
support information.

This is sent as an RFC because the vendor attribution and compatible
name should be reviewed.

Testing:
- make dt_binding_check: PASS
- srf04 module build: PASS
- Tested on Raspberry Pi 3 Model B+
- Kernel: 6.18.34+rpt-rpi-v8
- Device instantiated using only cytron,hc-sr04
- Trigger connected to GPIO17
- Echo connected to GPIO27 through a 5 V to 3.3 V resistor divider
- Driver bound and registered an IIO device
- in_distance_raw returned changing distance readings

Paweł Wiśniewski (3):
  dt-bindings: vendor-prefixes: Add Cytron Technologies
  dt-bindings: iio: proximity: Add Cytron HC-SR04
  iio: proximity: srf04: Add Cytron HC-SR04 support

 .../devicetree/bindings/iio/proximity/devantech-srf04.yaml   | 5 ++++-
 Documentation/devicetree/bindings/vendor-prefixes.yaml       | 2 ++
 drivers/iio/proximity/Kconfig                                | 1 +
 drivers/iio/proximity/srf04.c                                | 1 +
 4 files changed, 8 insertions(+), 1 deletion(-)


base-commit: 37e2f878a7a660a216cc7a60459995fefd150f25
-- 
2.47.3