iio: light: isl29501: Add support for the ISL29501 ToF sensor.

This patch adds support for the ISL29501 Time of Flight sensor.

Signed-off-by: Mathieu Othacehe <m.othacehe@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-isl29501 b/Documentation/ABI/testing/sysfs-bus-iio-isl29501
new file mode 100644
index 000000000000..d009cfbbd72b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-isl29501
@@ -0,0 +1,47 @@
+What:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_agc_gain
+What:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_agc_gain_bias
+KernelVersion:	4.18
+Contact:	linux-iio@vger.kernel.org
+Description:
+		This sensor has an automatic gain control (agc) loop
+		which sets the analog signal levels at an optimum
+		level by controlling programmable gain amplifiers. The
+		criteria for optimal gain is determined by the sensor.
+
+		Return the actual gain value as an integer in [0; 65536]
+		range when read from.
+
+		The agc gain read when measuring crosstalk shall be
+		written into in_proximity0_agc_gain_bias.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calib_phase_temp_a
+What:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calib_phase_temp_b
+What:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calib_phase_light_a
+What:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calib_phase_light_b
+KernelVersion:	4.18
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The sensor is able to perform correction of distance
+		measurements due to changing temperature and ambient
+		light conditions. It can be programmed to correct for
+		a second order error polynomial.
+
+		Phase data has to be collected when temperature and
+		ambient light are modulated independently.
+
+		Then a least squares curve fit to a second order
+		polynomial has to be generated from the data. The
+		resultant curves have the form ax^2 + bx + c.
+
+		From those two curves, a and b coefficients shall be
+		stored in in_proximity0_calib_phase_temp_a and
+		in_proximity0_calib_phase_temp_b for temperature and
+		in in_proximity0_calib_phase_light_a and
+		in_proximity0_calib_phase_light_b for ambient light.
+
+		Those values must be integer in [0; 8355840] range.
+
+		Finally, the c constant is set by the sensor
+		internally.
+
+		The value stored in sensor is displayed when read from.