boards: add support for shields x-nucleo-iks01a3

x-nucleo-iks01a3 shield is an arduino compatible companion board
which can be used on top of Nucleo standard boards. It extend
the Nucleo functionalities adding following MEMS sensor support:

    - LSM6DSO accel and gyro
    - LIS2MDL magnetometer
    - LIS2DW12 accel
    - LPS22HH pressure
    - HTS221 humidity

Signed-off-by: Armando Visconti <armando.visconti@st.com>

boards/shields/x_nucleo_iks01a3/doc/index.rst

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+.. _x-nucleo-iks01a3:
+
+X-NUCLEO-IKS01A3: MEMS Inertial and Environmental Multi sensor shield
+#####################################################################
+
+Overview
+********
+The X-NUCLEO-IKS01A3 is a motion MEMS and environmental sensor expansion board
+for the STM32 Nucleo. It is equipped with Arduino UNO R3 connector layout, and
+is designed around the LSM6DSO 3D accelerometer and 3D gyroscope, the LIS2MDL
+3-axis magnetometer, the LIS2DW12 3-axis accelerometer, the HTS221 humidity and
+temperature sensor, the LPS22HH pressure sensor, and the STTS751 temperature sensor.
+
+The X-NUCLEO-IKS01A3 interfaces with the STM32 microcontroller via the I2C pin,
+and it is possible to change the default I2C port.
+
+.. image:: img/x-nucleo-iks01a3.jpg
+     :width: 786px
+     :height: 543px
+     :align: center
+     :alt: X-NUCLEO-IKS01A3
+
+More information about the board can be found at the
+`X-NUCLEO-IKS01A3 website`_.
+
+Hardware Description
+********************
+
+X-NUCLEO-IKS01A3 provides the following key features:
+
+ - LSM6DO MEMS 3D accelerometer (±2/±4/±8/±16 g) and
+   3D gyroscope (±125/±250/±500/±1000/±2000 dps)
+ - LIS2MDL MEMS 3D magnetometer (±50 gauss)
+ - LIS2DW12 MEMS 3D accelerometer (±2/±4/±8/±16 g)
+ - LPS22HH MEMS pressure sensor, 260-1260 hPa absolute digital output barometer
+ - HTS221 capacitive digital relative humidity and temperature
+ - STTS751 Temperature sensor (-40 °C to +125 °C)
+ - DIL24 socket for additional MEMS adapters and other sensors (configurable in I2C or SPI)
+ - I2C sensor hub features on LSM6DSO available
+ - Compatible with STM32 Nucleo boards
+ - Equipped with Arduino UNO R3 connector
+ - RoHS compliant
+ - WEEE compliant
+
+Hardware Configuration
+**********************
+
+X-NUCLEO-IKS01A3 board connects the various devices on two separate I2C bus:
+
+- LIS2DW12 and LSM6DO are on I2C2
+- LIS2MDL, LPS22HH, HTS221 are STTS751 are on I2C1
+
+X-NUCLEO-IKS01A3 board can be configured in two different ways: Mode 1 and Mode 2
+
+
+Mode 1: Standard Mode
+=====================
+
+In standard I2C mode the two buses are connected together. As a consequence, all devices on the shield
+reside on the same I2C bus and are accessible from the main board thru I2C bus.
+
+The jumper configuration to activate this mode is:
+
+- JP7 => 1-2, 3-4 (I2C1 = I2C2, I2Cx=GND)
+- JP8 => 1-2, 3-4 (I2C1 = I2C2, I2Cx=GND)
+
+
+Mode 2: SensorHub Mode
+======================
+
+In SensorHub mode LSM6DSO and LIS2DW12 are connected to I2C2 and are accessible from the main board.
+All the other devices are connected to LSM6DSO master thru I2C1.
+
+The jumper configuration to activate this mode is:
+
+- JP7 => 2-3 (I2C1 = I2Cx)
+- JP8 => 2-3 (I2C1 = I2Cx)
+
+More information about X-NUCLEO-IKS01A3 configuration modes can be found in the
+`X-NUCLEO-IKS01A3 user manual`_
+
+Programming
+***********
+
+Two samples are provided as examples for ``x-nucleo-iks01a3`` shield:
+
+- :ref:`x-nucleo-iks01a3-std-sample` application, to be used when the shield is configured
+  in Standard Mode
+- :ref:`x-nucleo-iks01a3-shub-sample` application, to be used when the shield is configured
+  in SensorHub Mode
+
+See also :ref:`shields` for more details.
+
+References
+**********
+
+.. target-notes::
+
+.. _X-NUCLEO-IKS01A3 website:
+   http://www.st.com/en/ecosystems/x-nucleo-iks01a3.html
+
+.. _X-NUCLEO-IKS01A3 user manual:
+   https://www.st.com/resource/en/user_manual/dm00601501.pdf

boards/shields/x_nucleo_iks01a3/x_nucleo_iks01a3.overlay

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+/*
+ * Copyright (c) 2019 STMicroelectronics
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&arduino_i2c {
+
+	hts221@5f {
+		compatible = "st,hts221";
+		reg = <0x5f>;
+		label = "HTS221";
+	};
+
+	lps22hh@5d {
+		compatible = "st,lps22hh";
+		reg = <0x5d>;
+		drdy-gpios =  <&arduino_header 12 0>; /* D6 */
+		label = "LPS22HH";
+	};
+
+	lis2mdl@1e {
+		compatible = "st,lis2mdl-magn";
+		reg = <0x1e>;
+		label = "LIS2MDL";
+	};
+
+	lis2dw12@19 {
+		compatible = "st,lis2dw12";
+		reg = <0x19>;
+		irq-gpios =  <&arduino_header 3 0>; /* A3 */
+		label = "LIS2DW12";
+	};
+
+	lsm6dso@6b {
+		compatible = "st,lsm6dso";
+		reg = <0x6b>;
+		irq-gpios =  <&arduino_header 10 0>; /* D4 */
+		label = "LSM6DSO";
+	};
+};

boards/shields/x_nucleo_iks01a3/x_nucleo_iks01a3_shub.overlay

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+/*
+ * Copyright (c) 2019 STMicroelectronics
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&arduino_i2c {
+
+	lis2dw12@19 {
+		compatible = "st,lis2dw12";
+		reg = <0x19>;
+		irq-gpios =  <&arduino_header 3 0>; /* A3 */
+		label = "LIS2DW12";
+	};
+
+	lsm6dso@6b {
+		compatible = "st,lsm6dso";
+		reg = <0x6b>;
+		irq-gpios =  <&arduino_header 10 0>; /* D4 */
+		label = "LSM6DSO";
+	};
+};