[TOOLS] Add DTC (Devicetree Compiler) tools

Signed-off-by: GuEe-GUI <2991707448@qq.com>
2026-09-20 09:28:49 +08:00 · 2025-06-30 09:42:39 +08:00
parent 3e4f0ec015
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 - @subpage page_device_wlan
 - @subpage page_device_sensor
 - @subpage page_device_audio
+- @subpage page_device_dtc
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+@page page_device_dtc Devicetree Compiler
+
+# Introduction to the DTC
+
+Device Tree Compiler, dtc, takes as input a device-tree in a given format and outputs a device-tree in another format for booting kernels on embedded systems.
+Typically, the input format is "dts" (device-tree source), a human readable source format, and creates a "dtb" (device-tree binary), or binary format as output.
+
+> If the dtc tool is not installed on your host system, the dtc module will guide you through the installation.
+
+## Generate DTS
+
+When you have a DTB or FDT file from firmware or another runtime system, you might want to convert it into a DTS file for easier reading.
+You can do this in Python or your SConscript file. For example, assuming you have `dummpy.dtb`:
+
+```python
+import os, sys
+
+RTT_ROOT = os.getenv('RTT_ROOT')
+sys.path.append(RTT_ROOT + '/tools')
+
+from building import *
+import dtc
+
+dtc.dtb_to_dts(RTT_ROOT, "dummpy.dtb")
+```
+
+This will generate a dummpy.dts in the current directory. If a file with the same name already exists, it will be replaced.
+To avoid overwriting, you can specify a different output name:
+
+```python
+[...]
+
+dtc.dtb_to_dts(RTT_ROOT, "dummpy.dtb", "dummpy-tmp.dts")
+# or
+dtc.dtb_to_dts(RTT_ROOT, "dummpy.dtb", dts_name = "dummpy-tmp.dts")
+```
+
+## Generate DTB
+
+Before generating a DTB, you may want to review the basics of DTS syntax and structure: [DeviceTree Specification](https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html)
+
+### Include and Macros
+
+By default, dtc does not support C-style preprocessing (like cpp), but you can use the C preprocessor with your DTS files.
+Don't worry — our dtc module already includes this step.
+
+If your DTS file uses dt-bindings headers or macros, you can write something like:
+
+```c
+/*
+ * Used "#include" if header file need preprocessor,
+ * `components/drivers/include` and current directory path is default.
+ */
+#include <dt-bindings/size.h>
+#include "dummy.dtsi"
+/* Well, if dtsi is simple, you can use "/include/", it is supported by dtc */
+/include/ "chosen.dtsi"
+
+#define MMIO_BASE   0x10000
+#define MMIO_SIZE   SIZE_GB
+#define MEM_BASE    (MMIO_BASE + MMIO_SIZE)
+
+#ifndef CPU_HARDID
+#define CPU_HARDID  0
+#endif
+
+#ifndef SOC_INTC
+#define SOC_INTC    intc_a
+#endif
+
+/ {
+    #address-cells = <2>;
+    #size-cells = <2>;
+    /*
+     * Macros after "&" will be replaced,
+     * there will affect the interrupt controller in this SoC.
+     */
+    interrupt-parent = <&SOC_INTC>;
+
+    [...]
+
+    memory {
+        /* When there is a calculation, please use "()" to include them */
+        reg = <0x0 MEM_BASE 0x0 (3 * SIZE_GB)>;
+        device_type = "memory";
+    };
+
+    cpus {
+        #size-cells = <0>;
+        #address-cells = <1>;
+
+        /* Macros after "@" will be replaced */
+        cpu0: cpu@CPU_HARDID {
+            reg = <CPU_HARDID>;
+            device_type = "cpu";
+        };
+    };
+
+    /* Macros replace support phandle name, too */
+    intc_a: intc-a {
+        interrupt-controller;
+    };
+
+    intc_b: intc-b {
+        interrupt-controller;
+    };
+
+    [...]
+};
+```
+
+To generate the DTB:
+
+```python
+import os, sys
+
+RTT_ROOT = os.getenv('RTT_ROOT')
+sys.path.append(RTT_ROOT + '/tools')
+
+from building import *
+import dtc
+
+dtc.dts_to_dtb(RTT_ROOT, ["dummpy.dts"]
+```
+
+To append more include paths, for example, SoC DM headers:
+
+```python
+[...]
+
+dtc.dts_to_dtb(RTT_ROOT, ["dummpy.dts"], include_paths = ['dm/include', 'firmware'])
+```
+
+### Multiple DTB
+
+A single SoC may have different board variants.
+Example `dummy.dtsi` (common base):
+
+```c
+/* SoC dummy */
+/ {
+    #address-cells = <2>;
+    #size-cells = <2>;
+    model = "Dummy SoC Board";
+
+    [...]
+
+    chosen {
+        bootargs = "cma=8M coherent_pool=2M";
+    };
+
+    reserved-memory {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        isp_shm@100000 {
+            reg = <0x0 0x100000 0x0 0x100000>;
+        };
+
+        dsp_shm@200000 {
+            reg = <0x0 0x200000 0x0 0x100000>;
+        };
+    };
+
+    dsp {
+        status = "okay";
+    };
+
+    buddy {
+        isp = <&{/reserved-memory/isp_shm@100000}>;
+        dsp = <&{/reserved-memory/dsp_shm@200000}>;
+    };
+
+    uart0: uart {
+        status = "disabled";
+    };
+
+    i2c0: i2c {
+        status = "okay";
+    };
+
+    [...]
+};
+```
+
+For a vendor-specific variant (Vendor A):
+
+```c
+/* vendorA dummy */
+#include "dummy.dtsi"
+
+/ {
+    /* No phandle name can modify in place */
+    chosen {
+        bootargs = "console=uart0 cma=8M coherent_pool=2M";
+    };
+};
+
+/* Reference and modify direct if has phandle name */
+&uart0 {
+    status = "okay";
+    pinctrl-0 = <&uart0_m1>;
+};
+
+&i2c0 {
+    status = "disabled";
+};
+```
+
+To remove nodes or properties (Vendor B):
+
+```c
+/* vendorB dummy */
+#include "dummy.dtsi"
+
+/delete-node/ &dsp_shm;
+
+/ {
+    /* Delete in place if no phandle name */
+    /delete-node/ dsp;
+
+    /* Delete property */
+    buddy {
+        /delete-property/ dsp;
+    };
+};
+```
+
+To add new devices (Vendor C):
+
+```c
+/* vendorC dummy */
+#include "dummy.dtsi"
+
+&i2c0 {
+    rtc@0 {
+        clock-frequency = <32768>;
+    };
+};
+```
+
+Build all DTBs together:
+
+```python
+[...]
+
+dtc.dts_to_dtb(RTT_ROOT, ["dummpy-vendorA.dts", "dummpy-vendorB.dts", "dummpy-vendorC.dts"])
+```
+
+This will produce `dummpy-vendorA.dtb`, `dummpy-vendorB.dtb`, and `dummpy-vendorC.dtb`
+
+## Warnings
+
+DTC may produce warnings that are irrelevant or noisy.
+To suppress specific warnings:
+
+```python
+[...]
+
+dtc.dts_to_dtb(RTT_ROOT, ["dummpy.dts"], ignore_warning = ["simple_bus_reg", "unit_address_vs_reg", "clocks_is_cell", "gpios_property"])
+```
+
+Make sure your DTS is valid!
+
+## Raw options
+
+DTC provides additional command-line options (see dtc --help). You can pass raw options like this:
+
+```python
+[...]
+
+dtc.dtb_to_dts(RTT_ROOT, "dummpy.dtb", options = "--quiet")
+dtc.dts_to_dtb(RTT_ROOT, ["dummpy.dts"], options = "--quiet")
+```