If You want to use the SPI periphery of the beagleV Fire from a user-space application, just like on a microcontroller, You need to modify the device tree: You must add the spidev node to the spi periphery so linux adds the /dev/spidev character device driver on boot. The device tree is located in an image file in /boot/firmware/beaglev_fire.itb This file is a “Flattened Image Tree (FIT) Format”. While booting, U-Boot is loading this file. This image contains the kernel image and the device tree blob. To add spidev node You must:
- Extract the kernel image from the FIT image
- Extract the device tree blob from the FIT image
- Decompile the device tree blob to get the device tree source
- Add the spidev node to the device tree source
- Compile the device tree source
- Add the kernel image and device tree blob to a new FIT image