I need to make some changes in SPI in Linux. I found that IOCTL was the called function. So where is IOCTL defined? I am using Yocto linux on Intel edison (arduino breakout board).The function call is as:
ioctl (this->fd, SPI_IOC_MESSAGE(1),&msg);
In the IOCTL definition I want to add code to toggle some GPIOs. So how shall I do it?