Rtwo/kernel/motorola/sm8550/drivers/iio/imu/st_asm330lhh

NOTE

This repository contains an application specific driver version and may not reflect recent update. For up-to-date driver version, please refer to the following repository: STMems_Linux_IIO_drivers

Index

* Introduction
* Driver Integration details
* Android SensorHAL integration
* Linux SensorHAL integration
* More information
* Copyright

Introduction

This repository contains asm330lhh IMU STMicroelectronics MEMS sensor linux driver support for kernel version 4.19.

Data collected by asm330lhh STM sensor are pushed to userland through the kernel buffers of Linux IIO framework. User space applications can get sensor events by reading the related IIO devices created in the /dev directory (/dev/iio{x}). Please see IIO for more information.

Asm330lhh IMU STM MEMS sensor support I2C/SPI digital interface. Please refer to I2C and SPI for detailed documentation.

The STM Hardware Abstraction Layer (HAL) defines a standard interface for STM sensors allowing Android to be agnostic about low level driver implementation. The HAL library is packaged into modules (.so) file and loaded by the Android or Linux system at the appropriate time. For more information see AOSP HAL Interface

STM Sensor HAL is leaning on Linux IIO framework to gather data from sensor device drivers and to forward samples to the Android Framework

Driver Integration details

In order to explain how to integrate Asm330lhh IMU STM sensor into the kernel, please consider the following example

Source code integration

• Copy driver source code into your linux kernel target directory (e.g. drivers/iio/imu)
• Edit related Kconfig (e.g. drivers/iio/imu/Kconfig) adding ASM330LHH support:

    source "drivers/iio/imu/st_asm330lhh/Kconfig"

• Edit related Makefile (e.g. drivers/iio/imu/Makefile) adding the following line:

    obj-y += st_asm330lhh/

Device Tree configuration

To enable driver probing, add the asm330lhh node to the platform device tree as described below.

Required properties:

- compatible: "st,asm330lhh"

- reg: the I2C address or SPI chip select the device will respond to

- interrupt-parent: phandle to the parent interrupt controller as documented in interrupts

- interrupts: interrupt mapping for IRQ as documented in interrupts

Recommended properties for SPI bus usage:

- spi-max-frequency: maximum SPI bus frequency as documented in SPI

Optional properties:

- st,drdy-int-pin: MEMS sensor interrupt line to use (default 1)

I2C example (based on Raspberry PI 3):

  &i2c0 {
  	status = "ok";
  	#address-cells = <0x1>;
  	#size-cells = <0x0>;
  	asm330lhh@6b {
  		compatible = "st,asm330lhh";
  		reg = <0x6b>;
  		interrupt-parent = <&gpio>;
  		interrupts = <26 IRQ_TYPE_EDGE_RISING>;
  };

SPI example (based on Raspberry PI 3):

  &spi0 {
  	status = "ok";
  	#address-cells = <0x1>;
  	#size-cells = <0x0>;
  	asm330lhh@0 {
  		spi-max-frequency = <500000>;
  		compatible = "st,asm330lhh";
  		reg = <0>;
  		interrupt-parent = <&gpio>;
  		interrupts = <26 IRQ_TYPE_EDGE_RISING>;
  	};

Kernel configuration

Configure kernel with make menuconfig (alternatively use make xconfig or make qconfig)

  Device Drivers  --->
  	<M> Industrial I/O support  --->
  		Inertial measurement units  --->
  		<M>   STMicroelectronics ASM330LHH sensor  --->

More Information

http://st.com

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/iio

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/i2c

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/spi

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bings/interrupt-controller/interrupts.txt

Copyright Driver

Copyright (C) 2017 STMicroelectronics

This software is distributed under the GNU General Public License v2.0