dtb和dtc文件浅析
[TOC]
工具集
在之前的内核中,我们编译出来了可执行程序
linux-4.19-rc3/scripts/dtc/dtc
# 复制到bin下
sudo cp dtc /usr/bin/
常规用法如下:
转换到二进制 dtc>dtb dtc -I dtb -O dts -o output.dts arch/arm/boot/dts/jz2440.dtb
转换到可读文件 dtb>dtc dtc -I dts -O dtb -o jz2440.dtb output.dts
可以看下帮助
dtc -h
Usage: dtc [options]
Options: -[qI:O:o:V:d:R:S:p:a:fb:i:H:sW:E:@Ahv]
-q, --quiet
Quiet: -q suppress warnings, -qq errors, -qqq all
-I, --in-format
Input formats are:
dts - device tree source text
dtb - device tree blob
fs - /proc/device-tree style directory
-o, --out
Output file
-O, --out-format
Output formats are:
dts - device tree source text
dtb - device tree blob
asm - assembler source
-V, --out-version
Blob version to produce, defaults to 17 (for dtb and asm output)
-d, --out-dependency
Output dependency file
-R, --reserve
Make space for reserve map entries (for dtb and asm output)
-S, --space
Make the blob at least long (extra space)
-p, --pad
Add padding to the blob of long (extra space)
-a, --align
Make the blob align to the (extra space)
-b, --boot-cpu
Set the physical boot cpu
-f, --force
Try to produce output even if the input tree has errors
-i, --include
Add a path to search for include files
-s, --sort
Sort nodes and properties before outputting (useful for comparing trees)
-H, --phandle
Valid phandle formats are:
legacy - "linux,phandle" properties only
epapr - "phandle" properties only
both - Both "linux,phandle" and "phandle" properties
-W, --warning
Enable/disable warnings (prefix with "no-")
-E, --error
Enable/disable errors (prefix with "no-")
-@, --symbols
Enable generation of symbols
-A, --auto-alias
Enable auto-alias of labels
-h, --help
Print this help and exit
-v, --version
Print version and exit
dts格式
更多参考下这里
这个就放张图好了,总结起来就是只有一个根(root),子节点可以有子节点
当然存在着一些保留的关键字
Standard Properties
compatible
定义一系列的字符串, 用来指定内核中哪个
model
phandle
status
#address-cells
在它的子节点的reg属性中, 使用多少个u32整数来描述地址(address)
#size-cells
在它的子节点的reg属性中, 使用多少个u32整数来描述大小(size)
reg
virtual-reg
ranges
dma-ranges
name (deprecated)
device_type (deprecated)
dtb头部结构
struct fdt_header {
uint32_t magic;
uint32_t totalsize;
uint32_t off_dt_struct;
uint32_t off_dt_strings;
uint32_t off_mem_rsvmap;
uint32_t version;
uint32_t last_comp_version;
uint32_t boot_cpuid_phys;
uint32_t size_dt_strings;
uint32_t size_dt_struct;
};
dtb标识符
参见 5.4.1 Lexical structure
01 表示节点开始
02 节点结束
09 树结束
03 属性名字开始
04 nop
分析具体的文件
找到这里的文件
/arch/arm/boot/dts/jz2440.dtb jz2440.dts
具体的文件如下
// SPDX-License-Identifier: GPL-2.0
/*
* SAMSUNG SMDK2440 board device tree source
*
* Copyright (c) 2018 weidongshan@qq.com
* dtc -I dtb -O dts -o jz2440.dts jz2440.dtb
*/
#define S3C2410_GPA(_nr)((0<<16) + (_nr))
#define S3C2410_GPB(_nr)((1<<16) + (_nr))
#define S3C2410_GPC(_nr)((2<<16) + (_nr))
#define S3C2410_GPD(_nr)((3<<16) + (_nr))
#define S3C2410_GPE(_nr)((4<<16) + (_nr))
#define S3C2410_GPF(_nr)((5<<16) + (_nr))
#define S3C2410_GPG(_nr)((6<<16) + (_nr))
#define S3C2410_GPH(_nr)((7<<16) + (_nr))
#define S3C2410_GPJ(_nr)((8<<16) + (_nr))
#define S3C2410_GPK(_nr)((9<<16) + (_nr))
#define S3C2410_GPL(_nr)((10<<16) + (_nr))
#define S3C2410_GPM(_nr)((11<<16) + (_nr))
/dts-v1/;
/ {
model = "SMDK24440";
compatible = "samsung,smdk2440";
#address-cells = <1>;
#size-cells = <1>;
memory@30000000 {
device_type = "memory";
reg = <0x30000000 0x4000000>;
};
/*
cpus {
cpu {
compatible = "arm,arm926ej-s";
};
};
*/
chosen {
bootargs = "noinitrd root=/dev/mtdblock4 rw init=/linuxrc console=ttySAC0,115200";
};
led {
compatible = "jz2440_led";
pin = ;
};
};
