CONFIG_ADXL345 (not configurable)

modulename: adxl345_core.ko

configname: CONFIG_ADXL345

Linux Kernel Configuration
└─>Device Drivers
└─>Industrial I/O support
└─>Accelerometers
└─>ADXL345
In linux kernel since version 4.2 (release Date: 2015-08-30)  
source code:
drivers/iio/accel/adxl345_core.c
depends
CONFIG_IIO