1. Typical Device Tree File Types

File Extension	Meaning	Typical Purpose
.dts	Device Tree Source	Device Tree source, entry main file, one per board/model
.dtsi	Device Tree Source Include	Common sections, can be referenced by multiple .dts files, similar to .h in C
.dtb	Device Tree Blob	Compiled binary file, the file actually used by the kernel

2. Directory Structure and Hierarchy

Device Tree source files are usually located in the kernel source directory (using LCSC-TaishanPi-3M as example):

arch/
└── arm64/
    └── boot/
        └── dts/
            └── rockchip/
                ├── rk3576.dtsi
                ├── tspi-3m-rk3576.dts
                |── rk3576-pinctrl.dtsi
                ├── rockchip-pinconf.dtsi
                └── ... (other .dtsi/.dts/peripheral common dtsi, etc.)

• Each SoC (chip) has its own xxx.dtsi, such as rk3576.dtsi, describing all on-chip resources (CPU, on-chip peripherals, etc.)
• Each board/project has its own xxx.dts, such as tspi-3m-rk3576.dts, describing board-level information (power, external sensors, pin multiplexing, etc.), generally including its own SoC dtsi file

3. include Hierarchy Diagram

Using the specific board dts as the entry point, the system will recursively include all shared resources layer by layer.

• Board dts as the top level, #include the on-chip SoC, peripherals, and various common module dtsi files
• Each dtsi can continue to #include more underlying common resources

4. Classic dts/dtsi Relationship

tspi-3m-rk3576.dts header is written like this:

#include "rk3576.dtsi"
#include "rk3576-rk806.dtsi"

• Among them, rk3576.dtsi defines all SoC resources
• rk3576-rk806.dtsi defines board-level power chip 809 related resources
• Others can be connected through include.

5. Summary

• Board .dts is the main entry: ultimately compiled into dtb and passed to the kernel
• dtsi files ensure resource reusability: different boards can share the same SoC and peripheral dtsi templates
• All #includes are recursively merged into the final dtb

6. Common File Division Summary

File Name	Main Content/Division	Purpose
tspi-3m-rk3576.dts	Board entry file, project description, board hardware list, peripheral pins, model and compatible, core entry for all hardware configuration include	Compiled to dtb, used for kernel boot
rk3576.dtsi	SoC main chip common resource definitions (CPU, interrupt controller, on-chip peripherals, etc.)	Board common section, included by dts
rk3576-linux.dtsi / rk3576-android.dtsi	Custom resource configuration for different systems (Linux / Android)	Switch different configurations by system
rk3576-rk806.dtsi	Power chip PMIC related configuration information	Chip-level low-level power management
tspi-3m-rk3576-core.dtsi	Board-level core basic configuration (clocks, reset, kernel essential peripherals, etc.)	Ensures basic board operation
tspi-3m-rk3576-typec.dtsi	Type-C OTG related configuration	Type-C interface
tspi-3m-rk3576-usb-host.dtsi	USB host related peripherals	On-board USB HOST interface configuration
tspi-3m-rk3576-eth.dtsi	On-board Ethernet interface configuration	Network port/PHY/MDIO resources
tspi-3m-rk3576-sdio-wifibt.dtsi	On-board WiFi/Bluetooth module	SDIO wireless module/clock configuration
tspi-3m-rk3576-rtc.dtsi	Real-time clock/RTC resources	RTC chip/external clock configuration
tspi-3m-rk3576-csi0.dtsi/csi1.dtsi/csi3.dtsi	On-board camera MIPI-CSI channel configuration	Multi-channel camera MIPI interface
tspi-3m-rk3576-pcie.dtsi/sata.dtsi/ec20-4g.dtsi	Extension interfaces (choose one of three: PCIe, SATA, 4G module)	On-board MINI card, storage, communication
tspi-3m-rk3576-headset-onboard-mic.dtsi	Headphone and on-board microphone related	Audio input/output
tspi-3m-rk3576-hdmi.dtsi / ...-dp.dtsi	On-board HDMI, DP display interfaces	On-board video output interface separate management
tspi-3m-rk3576-dsi-cXXXXXXX.dtsi	On-board MIPI LCD display screen, divided by model	Adapts to multiple MIPI screen specifications
leds node (in dts main file)	On-board LED software/hardware description, status lights, etc.	GPIO-LED control/system indicator lights
... (other dtsi expanded as needed)	Other specialized resources, on-board modules, custom peripherals	Flexible adaptation for complex applications

Note:

• .dts is the main controller board/project entry, all includes converge here.
• .dtsi is reusable on-chip/peripheral/interface/module resources, select include based on platform and function.
• This splitting allows different hardware and customization needs to be batch adapted, modified, shared, and maintained!
• Commenting/uncommenting certain includes can enable/disable specific on-board hardware, providing high customization flexibility.