iio: add MEMSensing MSA311 3-axis accelerometer driver

MSA311 is a tri-axial, low-g accelerometer with I2C digital output for
sensitivity consumer applications. It has dynamic user-selectable full
scales range of +-2g/+-4g/+-8g/+-16g and allows acceleration measurements
with output data rates from 1Hz to 1000Hz.

This driver supports following MSA311 features:
    - IIO interface
    - Different power modes: NORMAL and SUSPEND (using pm_runtime)
    - ODR (Output Data Rate) selection
    - Scale and samp_freq selection
    - IIO triggered buffer, IIO reg access
    - NEW_DATA interrupt + trigger

Below features to be done:
    - Motion Events: ACTIVE, TAP, ORIENT, FREEFALL
    - Low Power mode

Datasheet: https://cdn-shop.adafruit.com/product-files/5309/MSA311-V1.1-ENG.pdfSigned-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220822175011.2886-4-ddrokosov@sberdevices.ruSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

MAINTAINERS

@@ -13176,6 +13176,12 @@ F:	drivers/mtd/
 F:	include/linux/mtd/
 F:	include/uapi/mtd/
 
+MEMSENSING MICROSYSTEMS MSA311 DRIVER
+M:	Dmitry Rokosov <ddrokosov@sberdevices.ru>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	drivers/iio/accel/msa311.c
+
 MEN A21 WATCHDOG DRIVER
 M:	Johannes Thumshirn <morbidrsa@gmail.com>
 L:	linux-watchdog@vger.kernel.org

drivers/iio/accel/Kconfig

@@ -541,6 +541,19 @@ config MMA9553
 	  To compile this driver as a module, choose M here: the module
 	  will be called mma9553.
 
+config MSA311
+	tristate "MEMSensing Digital 3-Axis Accelerometer Driver"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	select REGMAP_I2C
+	help
+	  Say yes here to build support for the MEMSensing MSA311
+	  accelerometer driver.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called msa311.
+
 config MXC4005
 	tristate "Memsic MXC4005XC 3-Axis Accelerometer Driver"
 	depends on I2C

drivers/iio/accel/Makefile

@@ -58,6 +58,8 @@ obj-$(CONFIG_MMA9551_CORE)	+= mma9551_core.o
 obj-$(CONFIG_MMA9551)		+= mma9551.o
 obj-$(CONFIG_MMA9553)		+= mma9553.o
 
+obj-$(CONFIG_MSA311)		+= msa311.o
+
 obj-$(CONFIG_MXC4005)		+= mxc4005.o
 obj-$(CONFIG_MXC6255)		+= mxc6255.o