设备树（device tree）学习笔记一

• 如何查看编译生成的设备树的内容？

在设备树学习的时候，如果可以看到最终生成的设备树的内容，对于我们学习设备树以及分析问题有很大帮助。这里我们需要使用设备树生成工具dtc的反汇编功能

[email protected]:~/tq2440/Linux/linux-4.0.1# ./scripts/dtc/dtc -h
Usage: dtc [options] <input file>

Options: -[qI:O:o:V:d:R:S:p:fb:i:H:sW:E:hv]
  -q, --quiet
    Quiet: -q suppress warnings, -qq errors, -qqq all
  -I, --in-format <arg>
    Input formats are:
        dts - device tree source text
        dtb - device tree blob
        fs  - /proc/device-tree style directory
-o, --out <arg>
    Output file
  -O, --out-format <arg>
    Output formats are:
        dts - device tree source text
        dtb - device tree blob
        asm - assembler source
  -V, --out-version <arg>
    Blob version to produce, defaults to %d (for dtb and asm output)
  -d, --out-dependency <arg>
    Output dependency file
  -R, --reserve <arg>
    tMake space for <number> reserve map entries (for dtb and asm output)
  -S, --space <arg>
    Make the blob at least <bytes> long (extra space)
  -p, --pad <arg>
    Add padding to the blob of <bytes> long (extra space)
  -b, --boot-cpu <arg>
    Set the physical boot cpu
  -f, --force
    Try to produce output even if the input tree has errors
  -i, --include <arg>
    Add a path to search for include files
  -s, --sort
    Sort nodes and properties before outputting (useful for comparing trees)
  -H, --phandle <arg>
    Valid phandle formats are:
        legacy - "linux,phandle" properties only
        epapr  - "phandle" properties only
        both   - Both "linux,phandle" and "phandle" properties
  -W, --warning <arg>
    Enable/disable warnings (prefix with "no-")
  -E, --error <arg>
    Enable/disable errors (prefix with "no-")
  -h, --help
    Print this help and exit
  -v, --version
    Print version and exit

假设我们最终的设备树文件是：arch/arm/boot/dts/s3c2416-smdk2416.dtb

./scripts/dtc/dtc -I dtb -O dts -o output.dts arch/arm/boot/dts/s3c2416-smdk2416.dtb

输出文件output.dts就是反汇编的结果，他就是实际生成的设备树。

• Linux配置，支持设备树

make menuconfig ---> Boot options ---> Flattened Device Tree support

• Linux 编译设备树

可以看看arch/arm/boot/dts/Makefile中你要的那个设备树的dtb文件是否配置上了。

make dtbs

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