Device Tree Memo | Angie An

Device tree allows the operating system or bootloader to know things like:

this system-on-chip has:

2 Cortex-A9 CPU cores
2 memory-mapped UART controllers of this variant, one with registers at 0xF1000000 and IRQ 23, and another with registers at 0xF1001000 and IRQ 24
3 I2C controllers of that variant, with registers at those memory-mapped address, those IRQs and taking their input clock from this source

simplified example of i2c controller and it’s sub node (eeprom0):

simplified example of spi controller and it’s sub node (flash0):

there is no need to describe usb devices in the device tree as sub node, the usb controller will discover them at runtime.

The linux kernel sources can be considered as the canonical(非常によく似た) location for device tree source files

arch//boot/dts