IIO callback buffer used for push in-kernel interfaces

configname: CONFIG_IIO_BUFFER_CB

Linux Kernel Configuration
└─>Device Drivers
└─>Industrial I/O support
└─>IIO callback buffer used for push in-kernel interfaces
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Should be selected by any drivers that do-inkernel push
usage. That is, those where the data is pushed to the consumer.