Linux device tree manually decompile dtb to generate source file dts

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In fact, you can install the dtc software package, but it is not recommended to do so. It is best to obtain this dtc tool by compiling the latest Linux kernel
The method of compiling the Linux kernel to generate the dtc tool
Download the latest Linux kernel, unzip it into ubuntu 20.04, and find a board defconfig, such as qemu

arch/arm/configs/vexpress_defconfig

$ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- vexpress_defconfig
$ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- dtbs

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Using the dtc tool compiled by the latest Linux kernel, it will be more reliable to compile or decompile the device tree file in this way. Of course, to study the Linux device tree, it is best to prepare the Linux compilation environment in advance
There is no need to recompile the Linux kernel here, just compile the device tree separatelymake ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- dtbs

That is to decompile the dtb device tree binary file into a dts device tree source file, here use the dtc tool
The command to decompile is as follows:

./dtc -I dtb -O dts vexpress-v2p-ca9.dtb -o vexpress-v2p-ca9_0603.dts

Just pay attention to the parameters:
./dtcIndicates the execution path of dtc, which can be specified according to the actual situation, ./dtcindicating that the dtc tool is under the current path
-I dtb -O dtsNote that here Iis Inputthe abbreviation of , that is, the input format: dtb, Oindicating Outputthe output format:dts
vexpress-v2p-ca9.dtb: The binary dtb file of the device tree, that is, the decompiled dtb file
-o vexpress-v2p-ca9_0603.dts, here -oin lowercase output, the output file, the following name can be defined by yourself, such asxxx.dts
The above operations can decompile a dtb file into a device tree source file dts

The Linux device tree file may be composed of a dts source file, multiple dtsi and .h header files, so only one original dts file is generated after decompilation. Compared with the content, it may be necessary to combine multiple dtsi files for viewing
As follows, I use the existing dts of Linux to generate dtb, and then decompile dtb into dts, and compare the contents of the files, and find some differences
After all, the generated dts is a combination of multiple files, but the content is basically the same. For example, you can compile the decompiled dts into dtb, and then verify whether the function is normal.

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As above, if there is only one dts file, the way to compile it into dtb is very simple, that is to use the dtc tool, the command is as follows:

$ ./dtc -I dts -O dtb vexpress-v2p-ca9_0603.dts -o vexpress-v2p-ca9_0603.dtb

If it is a complete device tree, including one dts, multiple dtsi and .h files, you need to use gcc preprocessing and then use dtc to compile it into dtb. Here you can use shell script or Makefile to achieve it. Related articles:
Makefile for manual compilation of Linux device tree files
Shell script for manual compilation of Linux device tree files

This article pays attention to how to decompile the device tree file dtb generated by Linux into a device tree source file dts file
Pay attention to the method of obtaining the device tree compilation tool dtc, it is best to obtain it through the latest Linux kernel compilation