iio: imu: Add support for the ADIS16460 IMU

The ADIS16460 device is a complete inertial system that includes a triaxial
gyroscope and a triaxial accelerometer. It's more simplified design than
that of the ADIS16480, and does not offer the triaxial magnetometers &
pressure sensors. It does also have a temperature sensor (like the
ADIS16480).
Since it is part of the ADIS16XXX family, it re-uses parts of the ADIS
library.

Naturally, the register map is different and much more simplified than the
ADIS16480 subfamily, so it cannot be integrated into that driver. A major
difference is that the registers are not paged.

One thing that is particularly special about it, is that it requires a
higher delay between CS changes (i.e. when CS goes up, the spec recommends
that it be brought down after a minimum of 16 uS).
Other ADIS chips require (via spec) a minimum of 2 uS between CS changes.
The kernel's 10 uS default should be fine for those other chips; they
haven't been tested with lower CS change delays yet.

Datasheet:
  https://www.analog.com/media/en/technical-documentation/data-sheets/adis16460.pdfSigned-off-by: Dragos Bogdan <dragos.bogdan@analog.com>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

MAINTAINERS

@@ -945,6 +945,13 @@ L:	linux-iio@vger.kernel.org
 F:	include/linux/iio/imu/adis.h
 F:	drivers/iio/imu/adis.c
 
+ANALOG DEVICES INC ADIS16460 DRIVER
+M:	Dragos Bogdan <dragos.bogdan@analog.com>
+S:	Supported
+L:	linux-iio@vger.kernel.org
+W:	http://ez.analog.com/community/linux-device-drivers
+F:	drivers/iio/imu/adis16460.c
+
 ANALOG DEVICES INC ADP5061 DRIVER
 M:	Stefan Popa <stefan.popa@analog.com>
 L:	linux-pm@vger.kernel.org

drivers/iio/imu/Kconfig

@@ -17,6 +17,18 @@ config ADIS16400
 	  adis16365, adis16400 and adis16405 triaxial inertial sensors
 	  (adis16400 series also have magnetometers).
 
+config ADIS16460
+	tristate "Analog Devices ADIS16460 and similar IMU driver"
+	depends on SPI
+	select IIO_ADIS_LIB
+	select IIO_ADIS_LIB_BUFFER if IIO_BUFFER
+	help
+	  Say yes here to build support for Analog Devices ADIS16460 inertial
+	  sensor.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called adis16460.
+
 config ADIS16480
 	tristate "Analog Devices ADIS16480 and similar IMU driver"
 	depends on SPI

drivers/iio/imu/Makefile

@@ -5,6 +5,7 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_ADIS16400) += adis16400.o
+obj-$(CONFIG_ADIS16460) += adis16460.o
 obj-$(CONFIG_ADIS16480) += adis16480.o
 
 adis_lib-y += adis.o