minimal driver, no IR current control and proximity/event
handling yet

v5:
* checkpatch warnings
* increase msleep() to 20 ms when waiting for data ready as
  measurement/conversion can take up to 100 ms, 1 ms is too short

v4 (address comments by Jonathan Cameron)
* remove SENSORS_ prefix in Kconfig
* change from IIO_INTENSITY to IIO_LIGHT
* move from staging

v3 (address comments by Shubhrajyoti Datta)
* cleanup Kconfig entry
* call I2C read/write functions directly

v2 (address comments by Lars-Peter Clausen and Jonathan Cameron)
* unify code for reading PS and AL data into
  parameterized _measure() function
* limit wait for data to become ready within 20 tries
* drop IIO_LIGHT channel, add SCALE to IIO_INTENSITY
* drop extra string arguments used for logging purpose only
Signed-off-by: NPeter Meerwald <pmeerw@pmeerw.net>
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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: NJohan Hovold <jhovold@gmail.com>
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>