driver for the TSL4531 family of 16-bit I2C ambient light
sensors; information is here:
http://www.ams.com/eng/Products/Light-Sensors/Ambient-Light-Sensor-ALS/TSL45315

the chip offers simple lux output

v3 (thanks Lars-Peter Clausen):
* add mutex to when updating integration time
* fix chip ID checking
* code cleanups
v2:
* rename to tsl4351
* use INT_TIME
Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Integration time is in seconds; it controls the measurement
time and influences the gain of a sensor.

There are two typical ways that scaling is implemented in a device:
1) input amplifier,
2) reference to the ADC is changed.
These both result in the accuracy of the ADC varying (by applying its
sampling over a more relevant range).

Integration time is a way of dealing with noise inherent in the analog
sensor itself.  In the case of a light sensor, a mixture of photon noise
and device specific noise.  Photon noise is dealt with by either improving
the efficiency of the sensor, (more photons actually captured) which is not
easily varied dynamically, or by integrating the measurement over a longer
time period.  Note that this can also be thought of as an averaging of a
number of individual samples and is infact sometimes implemented this way.
Altering integration time implies that the duration of a measurement changes,
a fact the device's user may be interested in.

Hence it makes sense to distinguish between integration time and simple
scale. In some devices both types of control are present and whilst they
will have similar effects on the amplitude of the reading, their effect
on the noise of the measurements will differ considerably.

Used by adjd_s311, tsl4531, tcs3472
The following drivers have similar controls (and could be adapted):
* tsl2563 (integration time is controlled via CALIBSCALE among other things)
* tsl2583 (has integration_time device_attr, but driver doesn't use channels yet)
* tsl2x7x (has integration_time attr)
Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Cc: Jon Brenner <jon.brenner@ams.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Barry Song <21cnbao@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Barry Song <21cnbao@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Barry Song <21cnbao@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Barry Song <21cnbao@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Barry Song <21cnbao@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Graff Yang <graff.yang@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Graff Yang <graff.yang@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

dev_err is preferred over pr_err.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
This patch also fixes the missing gpio_free call in remove.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Graff Yang <graff.yang@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

'break' after return is redundant. Remove it.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

'break' after return is redundant. Remove it.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

'break' after return is redundant. Remove it.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

'break' after return is redundant. Remove it.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

'break' after return is redundant. Remove it.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Updated with the current one.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Remove unnecessary work pending test before calling schedule_work().
It has been tested in queue_work_on() already. No functional changed.
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Add MODULE_ALIAS, so that auto module loading can work.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Fix the order of resources removal in the error path of mxs_lradc_probe()
and also in mxs_lradc_remove().
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

The usage of strict_strto*() is not preferred, because
strict_strto*() is obsolete. Thus, kstrto*() should be
used.

Previously, there were only strict_strtol(), strict_strtoul(),
strict_strtoull(), and strict_strtoll(). Thus, when converting
to the variables, only long, unsigned long, unsigned long long,
and long long can be used.

However, kstrto*() provides various functions handling all types
of variables. Therefore, the types of variables can be changed
properly.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Sysfs access to all channels.
Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Add a missing closing brace.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Shubhrajyoti Datta <shubhrajyoti@ti.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Silences the following warning:
drivers/staging/iio/light/tsl2x7x_core.c:553:70:
warning: Using plain integer as NULL pointer
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: J. August Brenner <jbrenner@taosinc.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: J. August Brenner <jbrenner@taosinc.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_iio_device_alloc makes the code simple. While at it also
fixed an uninitialized return with -EINVAL.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: J. August Brenner <jbrenner@taosinc.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
This also fixes an error in return type during clk_get
failure.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Roland Stigge <stigge@antcom.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

devm_* APIs are device managed and make code simpler.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>