iio: adc: rockchip_saradc: Add support for RV1106

The Successive Approximation ADC (SARADC) in RV1106 uses the v2
controller and supports:
- 10-bit resolution
- Up to 1MS/s sampling rate
- 2 single-ended input channels

"dt-bindings: iio: adc: rockchip-saradc: Add RV1106 compatible"
documents "rockchip,rv1106-saradc" as falling back to
"rockchip,rk3588-saradc" (see Link below). The two IP blocks are not
equivalent, though: per the RV1106 TRM v0.3, chapter 20 (SAR-ADC),
RV1106 only has 2 channels at 10-bit resolution, versus 8 channels
at 12-bit on RK3588. Without a dedicated match entry, the driver
binds via the fallback compatible and uses the RK3588 channel table,
which reports 8 channels instead of 2, and an in_voltage_scale that
is off by exactly 4x (4096 vs 1024 full-scale).

Add a dedicated compatible/data pair for RV1106 with the correct
2-channel, 10-bit layout.

Tested on a custom RV1106-based board, with:

  &saradc {
	vref-supply = <&vcc_saradc>; /* 1.8V fixed regulator */
	status = "okay";
  };

Before this patch:
  # ls /sys/bus/iio/devices/iio:device0/in_voltage*_raw | wc -l
  8
  # cat /sys/bus/iio/devices/iio:device0/in_voltage_scale
  0.439453125

After this patch:
  # ls /sys/bus/iio/devices/iio:device0/in_voltage*_raw | wc -l
  2
  # cat /sys/bus/iio/devices/iio:device0/in_voltage_scale
  1.757812500

Link: https://lore.kernel.org/all/20260714131631.v2.1.0b846080833e4b836793c43fc26d1c6d817cf9b4@changeid/
Signed-off-by: Vladislav Leonov <vlad@zlab.su>
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

0 files changed, 0 insertions, 0 deletions