CHAPTER
SIX
DEVICE TREE (DT)
6.1 Introduction
The following text briey describes the Device Tree and can be found in the Linux kernel Documentation
(https://docs.kernel.org/devicetree/usage-model.html)
“The “Open Firmware Device Tree”, or simply Devicetree (DT), is a data structure and language for
describing hardware. More specically, it is a description of hardware that is readable by an operating system
so that the operating system doesn’t need to hard code details of the machine.”
The kernel documentation is a really good source for a DT introduction. An overview of the device tree data
format can be found on the device tree usage page at devicetree.org.
6.2 PHYTEC i.MX 93 BSP Device Tree Concept
The following sections explain some rules PHYTEC has dened on how to set up device trees for our i.MX
93 SoC-based boards.
6.2.1 Device Tree Structure
• Module.dtsi - Module includes all devices mounted on the SoM, such as PMIC and RAM.
• Board.dts - include the module dtsi le. Devices that come from the i.MX 93 SoC but are just routed
down to the carrier board and used there are included in this dts.
• Overlay.dtso - enable/disable features depending on optional hardware that may be mounted or missing
on SoM or baseboard (e.g SPI ash or PEB-AV-10)
From the root directory of the Linux Kernel our devicetree les for i.MX 9 platforms can be found in
arch/arm64/boot/dts/freescale/.
6.2.2 Device Tree Overlay
Device Tree overlays are device tree fragments that can be merged into a device tree during boot time. These
are for example hardware descriptions of an expansion board. They are instead of being added to the device
tree as an extra include, now applied as an overlay. They also may only contain setting the status of a node
depending on if it is mounted or not. The device tree overlays are placed next to the other device tree les
in our Linux kernel repository in the folder arch/arm64/boot/dts/freescale/.
Available overlays for phyboard-segin-imx93-2.conf are:
imx93-phyboard-segin-peb-av-02.dtbo
imx93-phyboard-segin-peb-eval-01.dtbo
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