IIO: ADC: New driver for the AD7298 8-channel SPI ADC

This patch adds support for the
AD7298:  8-Channel, 1MSPS, 12-Bit SAR ADC with Temperature Sensor
via SPI bus.

This patch replaces the existing ad7298.c driver completely.
It was necessary since, the old driver did not comply with the
IIO ABI for such devices.

Changes since V1:
IIO: ADC: New driver for the AD7298 8-channel SPI ADC

Add documentation for new sysfs file tempX_input.
Simplify bit defines.
Remove outdated comments.
Fix indention style.
ad7298_show_temp():
	Add locking.
	Simplify temperature calculation.
	Change temperature result from degrees into milli degrees Celsius.
	Rename file according to new sysfs ABI documentation

Add timestamp attributes.
Revise timestamp handling accordingly.
Preset timestamp generation.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Reviewed-by: Shubhrajyoti <Shubhrajyoti@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Documentation/sysfs-bus-iio

@@ -111,6 +111,12 @@ Description:
 		sensor is associated with one part of a compound device (e.g.
 		a gyroscope axis).
 
+What:		/sys/bus/iio/devices/deviceX/tempX_input
+KernelVersion:	2.6.38
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Scaled temperature measurement in milli degrees Celsius.
+
 What:		/sys/bus/iio/devices/deviceX/accel_x_raw
 What:		/sys/bus/iio/devices/deviceX/accel_y_raw
 What:		/sys/bus/iio/devices/deviceX/accel_z_raw

drivers/staging/iio/adc/Kconfig

@@ -49,11 +49,14 @@ config AD7291
 	  temperature sensors.
 
 config AD7298
-	tristate "Analog Devices AD7298 temperature sensor and ADC driver"
+	tristate "Analog Devices AD7298 ADC driver"
 	depends on SPI
 	help
 	  Say yes here to build support for Analog Devices AD7298
-	  temperature sensors and ADC.
+	  8 Channel ADC with temperature sensor.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad7298.
 
 config AD7314
 	tristate "Analog Devices AD7314 temperature sensor driver"

drivers/staging/iio/adc/Makefile

@@ -25,10 +25,13 @@ ad7887-y := ad7887_core.o
 ad7887-$(CONFIG_IIO_RING_BUFFER) += ad7887_ring.o
 obj-$(CONFIG_AD7887) += ad7887.o
 
+ad7298-y := ad7298_core.o
+ad7298-$(CONFIG_IIO_RING_BUFFER) += ad7298_ring.o
+obj-$(CONFIG_AD7298) += ad7298.o
+
 obj-$(CONFIG_AD7150) += ad7150.o
 obj-$(CONFIG_AD7152) += ad7152.o
 obj-$(CONFIG_AD7291) += ad7291.o
-obj-$(CONFIG_AD7298) += ad7298.o
 obj-$(CONFIG_AD7314) += ad7314.o
 obj-$(CONFIG_AD7745) += ad7745.o
 obj-$(CONFIG_AD7816) += ad7816.o