设备树DTS 学习：2-设备树语法
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四、设备树语法
1.节点node
- 节点名称：每个节点必须有一个“<名称>[@<设备地址>]”形式的名字：
<名称> 就是一个不超过31位的简单 ascii 字符串，节点的命名应该根据它所体现的是什么样的设备。 - <设备地址>用来访问该设备的主地址，并且该地址也在节点的 reg 属性中列出，同级节点命名必须是唯一的，但只要地址不同，多个节点也可以使用一样的通用名称，当然设备地址也是可选的，可以有也可以没有
- 树中每个表示一个设备的节点都需要一个 compatible 属性
1）节点名称name
- name描述设备类型，比如网口宜用ethernet；如果有地址，则用@指定地址
<name>[@<unit-address>]
举例：
cpus {}
serial@101F2000 { }
ethernet@0,0 {}2.属性property
简单的键－值对，它的值可以为空或者包含一个任意字节流。虽然数据类型并没有编码进数据结构，但在设备树源文件中任有几个基本的
数据表示形式
:
- 文本字符串（无结束符）可以用双引号表示：
string-property = "a string" - Cells是 32 位无符号整数，用尖括号限定：
cell-property = <0xbeef 123 0xabcd1234> - 二进制数据用方括号限定：
binary-property = [01 23 45 67]; - 不同表示形式的数据可以使用逗号连在一起：
mixed-property = "a string", [01 23 45 67], <0x12345678>; - 逗号也可用于创建字符串列表：
string-list = "red fish", "blue fish";
- 文本字符串（无结束符）可以用双引号表示：
1）compatible属性
- 指定了系统的名称，是一个字符串列表，它包含了一个“<制造商>,<型号>”形式的字符串。重要的是要指定一个确切的设备，并且包括制造商的名字，以避免命名空间冲突。
compatible = "<manufacturer>,<model>" [, "model"]
#manufacturer指定厂家名，model指定特定设备型号，后续的model指定兼容的设备型号。对应到具体的驱动文件定义的设备，如spidev 对应于openwrt/build_dir/target-mipsel_24kc_glibc-2.24/linux-ramips_mt7688/linux-4.4.167/drivers/spi/spidev.c的spidev_spi_driver的name。
举例：
compatible = "smc, smc91c11";
compatible = "samsung,k8f1315ebm", "cfi-flash"; 2）#address-cells和#size-cells属性
#address-cells = <1>: 基地址、片选号等绝对起始地址所占字长，单位uint32#size-cells = <1>: 长度所占字长，单位uint32
external-bus {
#address-cells = <2>
#size-cells = <1>;
ethernet@0,0 {
compatible = "smc,smc91c111";
reg = <0 0 0x1000>; // 地址占两个cells， 长度占1个cells
nterrupts = < 5 2 >;
};
}3）reg属性
reg = ...: addr表明基址，len表明长度，addr由#address-cells个uint32值组成，len由#size-cells个uint32值组成。表明了设备使用的一个地址范围。
/{
compatible = "acme,coyotes-revenge";
#address-cells = <1>;
#size-cells = <1>;
serial@101f2000 {
compatible = "arm,pl011";
reg = <0x101f2000 0x1000 >;
interrupts = < 2 0 >;
};
｝4）中断属性
interrupt-parent - 设备结点透过它来指定它所依附的中断控制器的phandle，当结点没有指定interrupt-parent时，则从父级结点继承。
interrupt-controller - 一个空的属性定义该节点作为一个
接收中断信号的设备#interrupt-cells - 表明连接此中断控制器的设备的interrupts属性的cell大小（个数）
interrupts - 一个中断指示符的列表，对应于该设备上的每个中断输出信号，在ARM GIC中：
当#interrupt-cells为3时，interrupts包含三个cells，如
interrupts = <0 168 4> [, <0 169 4>]- 第一个cell代表中断类型：0 表示SPI中断，1 表示PPI中断
- 第二个cell代表具体的中断类型：、
- PPI中断：私有外设中断(Private Peripheral Interrupt)，是每个CPU私有的中断。最多支持16个PPI中断，范围【0 - 15】。
- SPI中断类型：公用外设中断(Shared Peripheral Interrupt)，最多可以支持988个外设中断，范围【0 - 987】。
- 第三个cell代表中断触发标志：
- bits [ 3 ：0 ] 触发类型和级别标志：
1 = 低- 至- 高边沿触发
2 = 高- 到- 低边沿触发
4 = 活跃的高水平- 敏感
8 = 低电平有效- 敏感 - bits [ 15 ：8 ] PPI中断cpu掩码。每个位对应于每个位附加到GIC的8个可能的cpu。指示设置为“1”的位中断被连接到该CPU 。只有有效的PPI中断。
- bits [ 3 ：0 ] 触发类型和级别标志：
当#interrupt-cells为2时，interrupts包含2个cells，如
interrupts = <2 4>- 第一个cell代表具体的中断类型：
- SGI中断：软件触发中断(Software Generated Interrupt)，通常用于多核间通讯，最多支持16个SGI中断，硬件中断号从ID0~ID15。
- PPI中断：私有外设中断(Private Peripheral Interrupt)，是每个CPU私有的中断。最多支持16个PPI中断，硬件中断号从ID16~ID31。
- SPI中断类型：公用外设中断(Shared Peripheral Interrupt)，最多可以支持988个外设中断，硬件中断号从ID32~ID1019。
- 第二个cell代表中断触发标志：
- bits [ 3 ：0 ] 触发类型和级别标志：
1 = 低- 至- 高边沿触发
2 = 高- 到- 低边沿触发
4 = 活跃的高水平- 敏感
8 = 低电平有效- 敏感 - bits [ 15 ：8 ] PPI中断cpu掩码。每个位对应于每个位附加到GIC的8个可能的cpu。指示设置为“1”的位中断被连接到该CPU 。只有有效的PPI中断。
- bits [ 3 ：0 ] 触发类型和级别标志：
备注：ARM GIC V3说明：kernel/Documentation/devicetree/bindings/arm/gic.txt
- 第一个cell代表具体的中断类型：
reg - 指定基物理地址和所述GIC寄存器的大小
- 第一个区域是GIC分销商的注册基数和规模。
- 第二个区域是GIC cpu 接口寄存器的基数和大小。
/ {
compatible = "acme,coyotes-revenge";
#address-cells = <1>;
#size-cells = <1>;
interrupt-parent = <&intc>;//指定依附的中断控制器是intc
serial@101f0000 { //子节点：串口设备
compatible = "arm,pl011";
reg = <0x101f0000 0x1000 >;
interrupts = < 1 0 >;
};
intc: interrupt-controller@10140000 { //intc中断控制器
compatible = "arm,pl190";
reg = <0x10140000 0x1000 >;
interrupt-controller;//定义为中断控制器设备
#interrupt-cells = <2>;
};
｝四、设备树文件分析
mt7628/mt7688的设备树管脚配置参考openwrt/build_dir/target-mipsel_24kc_glibc-2.24/linux-ramips_mt7688/linux-4.4.167/arch/mips/ralink/mt7620.c文件
//mt7628an.dtsi文件
/ {
#address-cells = <1>;
#size-cells = <1>;
compatible = "ralink,mtk7628an-soc";
cpus {
cpu@0 {
compatible = "mips,mips24KEc";
};
};
chosen {
bootargs = "console=ttyS0,57600";
};
aliases {
serial0 = &uartlite;
};
cpuintc: cpuintc@0 {
#address-cells = <0>;
#interrupt-cells = <1>;
interrupt-controller;
compatible = "mti,cpu-interrupt-controller";
};
palmbus: palmbus@10000000 {
compatible = "palmbus";
reg = <0x10000000 0x200000>;
ranges = <0x0 0x10000000 0x1FFFFF>;
#address-cells = <1>;
#size-cells = <1>;
sysc: sysc@0 {
compatible = "ralink,mt7620a-sysc";
reg = <0x0 0x100>;
};
watchdog: watchdog@120 {
compatible = "ralink,mt7628an-wdt", "mtk,mt7621-wdt";
reg = <0x120 0x10>;
resets = <&rstctrl 8>;
reset-names = "wdt";
interrupt-parent = <&intc>;
interrupts = <24>;
};
intc: intc@200 {
compatible = "ralink,mt7628an-intc", "ralink,rt2880-intc";
reg = <0x200 0x100>;
resets = <&rstctrl 9>;
reset-names = "intc";
interrupt-controller;
#interrupt-cells = <1>;
interrupt-parent = <&cpuintc>;
interrupts = <2>;
ralink,intc-registers = <0x9c 0xa0
0x6c 0xa4
0x80 0x78>;
};
memc: memc@300 {
compatible = "ralink,mt7620a-memc", "ralink,rt3050-memc";
reg = <0x300 0x100>;
resets = <&rstctrl 20>;
reset-names = "mc";
interrupt-parent = <&intc>;
interrupts = <3>;
};
gpio@600 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "mtk,mt7628-gpio", "mtk,mt7621-gpio";
reg = <0x600 0x100>;
interrupt-parent = <&intc>;
interrupts = <6>;
gpio0: bank@0 {
reg = <0>;
compatible = "mtk,mt7621-gpio-bank";
gpio-controller;
#gpio-cells = <2>;
};
gpio1: bank@1 {
reg = <1>;
compatible = "mtk,mt7621-gpio-bank";
gpio-controller;
#gpio-cells = <2>;
};
gpio2: bank@2 {
reg = <2>;
compatible = "mtk,mt7621-gpio-bank";
gpio-controller;
#gpio-cells = <2>;
};
};
i2c: i2c@900 {
compatible = "mediatek,mt7621-i2c";
reg = <0x900 0x100>;
resets = <&rstctrl 16>;
reset-names = "i2c";
#address-cells = <1>;
#size-cells = <0>;
status = "disabled";
pinctrl-names = "default";
pinctrl-0 = <&i2c_pins>;
};
i2s: i2s@a00 {
compatible = "mediatek,mt7628-i2s";
reg = <0xa00 0x100>;
resets = <&rstctrl 17>;
reset-names = "i2s";
interrupt-parent = <&intc>;
interrupts = <10>;
txdma-req = <2>;
rxdma-req = <3>;
dmas = <&gdma 4>,
<&gdma 6>;
dma-names = "tx", "rx";
status = "disabled";
};
spi0: spi@b00 {
compatible = "ralink,mt7621-spi";
reg = <0xb00 0x100>;
resets = <&rstctrl 18>;
reset-names = "spi";
#address-cells = <1>;
#size-cells = <0>;
pinctrl-names = "default";
pinctrl-0 = <&spi_pins>;
status = "disabled";
};
uartlite: uartlite@c00 {
compatible = "ns16550a";
reg = <0xc00 0x100>;
reg-shift = <2>;
reg-io-width = <4>;
no-loopback-test;
clock-frequency = <40000000>;
resets = <&rstctrl 12>;
reset-names = "uartl";
interrupt-parent = <&intc>;
interrupts = <20>;
pinctrl-names = "default";
pinctrl-0 = <&uart0_pins>;
};
uart1: uart1@d00 {
compatible = "ns16550a";
reg = <0xd00 0x100>;
reg-shift = <2>;
reg-io-width = <4>;
no-loopback-test;
clock-frequency = <40000000>;
resets = <&rstctrl 19>;
reset-names = "uart1";
interrupt-parent = <&intc>;
interrupts = <21>;
pinctrl-names = "default";
pinctrl-0 = <&uart1_pins>;
status = "disabled";
};
uart2: uart2@e00 {
compatible = "ns16550a";
reg = <0xe00 0x100>;
reg-shift = <2>;
reg-io-width = <4>;
no-loopback-test;
clock-frequency = <40000000>;
resets = <&rstctrl 20>;
reset-names = "uart2";
interrupt-parent = <&intc>;
interrupts = <22>;
pinctrl-names = "default";
pinctrl-0 = <&uart2_pins>;
status = "disabled";
};
pwm: pwm@5000 {
compatible = "mediatek,mt7628-pwm";
reg = <0x5000 0x1000>;
resets = <&rstctrl 31>;
reset-names = "pwm";
pinctrl-names = "default";
pinctrl-0 = <&pwm0_pins>, <&pwm1_pins>;
status = "disabled";
};
pcm: pcm@2000 {
compatible = "ralink,mt7620a-pcm";
reg = <0x2000 0x800>;
resets = <&rstctrl 11>;
reset-names = "pcm";
interrupt-parent = <&intc>;
interrupts = <4>;
status = "disabled";
};
gdma: gdma@2800 {
compatible = "ralink,rt3883-gdma";
reg = <0x2800 0x800>;
resets = <&rstctrl 14>;
reset-names = "dma";
interrupt-parent = <&intc>;
interrupts = <7>;
#dma-cells = <1>;
#dma-channels = <16>;
#dma-requests = <16>;
status = "disabled";
};
};
pinctrl: pinctrl {
compatible = "ralink,rt2880-pinmux";
pinctrl-names = "default";
pinctrl-0 = <&state_default>;
state_default: pinctrl0 {
};
spi_pins: spi {
spi {
ralink,group = "spi";
ralink,function = "spi";
};
};
spi_cs1_pins: spi_cs1 {
spi_cs1 {
ralink,group = "spi cs1";
ralink,function = "spi cs1";
};
};
i2c_pins: i2c {
i2c {
ralink,group = "i2c";
ralink,function = "i2c";
};
};
uart0_pins: uartlite {
uartlite {
ralink,group = "uart0";
ralink,function = "uart0";
};
};
uart1_pins: uart1 {
uart1 {
ralink,group = "uart1";
ralink,function = "uart1";
};
};
uart2_pins: uart2 {
uart2 {
ralink,group = "uart2";
ralink,function = "uart2";
};
};
sdxc_pins: sdxc {
sdxc {
ralink,group = "sdmode";
ralink,function = "sdxc";
};
};
pwm0_pins: pwm0 {
pwm0 {
ralink,group = "pwm0";
ralink,function = "pwm0";
};
};
pwm1_pins: pwm1 {
pwm1 {
ralink,group = "pwm1";
ralink,function = "pwm1";
};
};
pcm_i2s_pins: i2s {
i2s {
ralink,group = "i2s";
ralink,function = "pcm";
};
};
};
rstctrl: rstctrl {
compatible = "ralink,mt7620a-reset", "ralink,rt2880-reset";
#reset-cells = <1>;
};
clkctrl: clkctrl {
compatible = "ralink,rt2880-clock";
#clock-cells = <1>;
};
usbphy: usbphy@10120000 {
compatible = "ralink,mt7628an-usbphy", "mediatek,mt7620-usbphy";
reg = <0x10120000 0x1000>;
#phy-cells = <1>;
resets = <&rstctrl 22 &rstctrl 25>;
reset-names = "host", "device";
clocks = <&clkctrl 22 &clkctrl 25>;
clock-names = "host", "device";
};
sdhci: sdhci@10130000 {
compatible = "ralink,mt7620-sdhci";
reg = <0x10130000 0x4000>;
interrupt-parent = <&intc>;
interrupts = <14>;
pinctrl-names = "default";
pinctrl-0 = <&sdxc_pins>;
status = "disabled";
};
ehci: ehci@101c0000 {
compatible = "generic-ehci";
reg = <0x101c0000 0x1000>;
phys = <&usbphy 1>;
phy-names = "usb";
interrupt-parent = <&intc>;
interrupts = <18>;
};
ohci: ohci@101c1000 {
compatible = "generic-ohci";
reg = <0x101c1000 0x1000>;
phys = <&usbphy 1>;
phy-names = "usb";
interrupt-parent = <&intc>;
interrupts = <18>;
};
ethernet: ethernet@10100000 {
compatible = "ralink,rt5350-eth";
reg = <0x10100000 0x10000>;
interrupt-parent = <&cpuintc>;
interrupts = <5>;
resets = <&rstctrl 21 &rstctrl 23>;
reset-names = "fe", "esw";
mediatek,switch = <&esw>;
};
esw: esw@10110000 {
compatible = "mediatek,mt7628-esw", "ralink,rt3050-esw";
reg = <0x10110000 0x8000>;
resets = <&rstctrl 23>;
reset-names = "esw";
interrupt-parent = <&intc>;
interrupts = <17>;
};
pcie: pcie@10140000 {
compatible = "mediatek,mt7620-pci";
reg = <0x10140000 0x100
0x10142000 0x100>;
#address-cells = <3>;
#size-cells = <2>;
interrupt-parent = <&cpuintc>;
interrupts = <4>;
resets = <&rstctrl 26 &rstctrl 27>;
reset-names = "pcie0", "pcie1";
clocks = <&clkctrl 26 &clkctrl 27>;
clock-names = "pcie0", "pcie1";
status = "disabled";
device_type = "pci";
bus-range = <0 255>;
ranges = <
0x02000000 0 0x00000000 0x20000000 0 0x10000000 /* pci memory */
0x01000000 0 0x00000000 0x10160000 0 0x00010000 /* io space */
>;
pcie-bridge {
reg = <0x0000 0 0 0 0>;
#address-cells = <3>;
#size-cells = <2>;
device_type = "pci";
};
};
wmac: wmac@10300000 {
compatible = "mediatek,mt7628-wmac";
reg = <0x10300000 0x100000>;
interrupt-parent = <&cpuintc>;
interrupts = <6>;
status = "disabled";
mediatek,mtd-eeprom = <&factory 0x0000>;
};
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