Sensirion SGP30/SGPC3 Linux Kernel Driver

The sgp30 driver for the Sensirion SGP30 and SGPC3 drivers is based on the IIO subsystem

Requirements

Kernel with the following config options set, either as module or compiled in. The config options must be listed in .config (e.g. selected with make menuconfig)

Minimal driver requirements:

• CONFIG_CRC8
• CONFIG_IIO

Directory Structure

/: The root directory contains the Makefile needed for out-of-tree module builds.

/sgp30: The sgp30 directory contains the driver source and Kconfig as needed for upstream merging with the Linux sources.

Building

Local Machine

Compiling for your local machine is useful to test if the driver compiles correctly. Prerequisites are the kernel headers and build tools.

# Install dependencies
sudo apt install build-essential linux-headers-$(uname -r)
# configure
export KERNELDIR=/lib/modules/$(uname -r)/build
# build
make -j

To check for style issues we can use the check target

make check

Cross Compiling

To cross compile, one needs to install a cross compilation tool chain and set the ARCH and CROSS_COMPILE environment variables accordingly:

# Example to cross compile for raspbian
export ARCH=arm
export CROSS_COMPILE=~/opt/toolchain/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf-

Usage

The driver is meant for direct use with sysfs or libiio. Errors are printed to the kernel log (dmesg)

Loading the Kernel Module

Load the dependencies of the sgp30.ko kernel module:

sudo modprobe industrialio
sudo modprobe crc8

Load the kernel module with the appropriate command:

• Out-of-tree build

  ```bash
  sudo insmod sgp30.ko
  ```
  

• In-kernel build

  ```bash
  sudo modprobe sgp30
  ```
  

Instantiation

Instantiate the driver on the correct i2c bus with

echo sgp30 0x58 | sudo tee /sys/class/i2c-adapter/i2c-1/new_device

Only sgp30 and sgpc3 are permissible names. Use of the name of the wrong chip will result in an error during probing.

Operation

Query device files by reading from the iio subsytem's device:

cat /sys/bus/iio/devices/iio\:device0/in_selftest
OK

or alternatively on the i2c bus: /sys/bus/i2c/devices/1-0058/iio:device0/

Unloading

Unload the driver by removing the device instance and then unloading the module.

echo 0x58 | sudo tee /sys/class/i2c-adapter/i2c-1/delete_device
sudo rmmod sgp30