iio: add LM3533 ambient-light-sensor driver

Add sub-driver for the ambient-light-sensor interface on National
Semiconductor / TI LM3533 lighting power chips.

The sensor interface can be used to control the LEDs and backlights of
the chip through defining five light zones and three sets of
corresponding output-current values.

The driver provides raw and mean adc readings along with the current
light zone through sysfs. A threshold event can be generated on zone
changes. The ALS-control output values can be set per zone for the three
current output channels.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-light-lm3533-als b/Documentation/ABI/testing/sysfs-bus-iio-light-lm3533-als
new file mode 100644
index 000000000000..694a52c8cf82
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-light-lm3533-als
@@ -0,0 +1,62 @@
+What:		/sys/.../events/in_illuminance0_thresh_either_en
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Event generated when channel passes one of the four thresholds
+		in each direction (rising|falling) and a zone change occurs.
+		The corresponding light zone can be read from
+		in_illuminance0_zone.
+
+What:		/sys/.../events/in_illuminance0_threshY_hysteresis
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Get the hysteresis for thresholds Y, that is,
+
+		threshY_hysteresis = threshY_raising - threshY_falling
+
+What:		/sys/.../events/illuminance_threshY_falling_value
+What:		/sys/.../events/illuminance_threshY_raising_value
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Specifies the value of threshold that the device is comparing
+		against for the events enabled by
+		in_illuminance0_thresh_either_en (0..255), where Y in 0..3.
+
+		Note that threshY_falling must be less than or equal to
+		threshY_raising.
+
+		These thresholds correspond to the eight zone-boundary
+		registers (boundaryY_{low,high}) and defines the five light
+		zones.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_illuminance0_zone
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Get the current light zone (0..4) as defined by the
+		in_illuminance0_threshY_{falling,rising} thresholds.
+
+What:		/sys/bus/iio/devices/iio:deviceX/out_currentY_raw
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Get output current for channel Y (0..255), that is,
+		out_currentY_currentZ_raw, where Z is the current zone.
+
+What:		/sys/bus/iio/devices/iio:deviceX/out_currentY_currentZ_raw
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the output current for channel out_currentY when in zone
+		Z (0..255), where Y in 0..2 and Z in 0..4.
+
+		These values correspond to the ALS-mapper target registers for
+		ALS-mapper Y + 1.