驱动进化之路

1. 面向对象分离硬件资源驱动思想

背景<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：
在早期的嵌入设备和计算机系统中<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，硬件驱动程序通常是直接和硬件紧密耦合的<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。这种方式导致了驱动程序难以维护和扩展<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，因为每种新的硬件都可能需要全新的驱动代码<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

思想<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

• 模块化<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：将硬件相关的代码从系统的其他部分中分离出来<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，形成独立的模块<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（驱动模块<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>。
• 抽象层<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：引入硬件抽象层<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（HAL<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>，使得上层软件可以不直接操作硬件<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，而是通过一层抽象的接口来进行<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 封装<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：使用面向对象的编程思想<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，将硬件的操作封装成类或对象<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，这样可以更容易管理和重用代码<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

技术细节<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

• 使用类的继承和多态来实现不同硬件的抽象和具体实现<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 提供统一的接口来访问硬件资源<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，降低了对具体硬件的依赖<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

例子<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：假设有一个LED连接到一个GPIO引脚上<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

• 模块化<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：创建一个独立的LED驱动模块<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，而不是将LED操作代码直接嵌入到应用层代码中<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 抽象层<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：定义一个抽象的LED类<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，包含打开<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>、关闭等方法<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"highlight cpp"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"code"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// LED抽象类 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">class "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title class_"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">LED { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">public: "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"function"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">virtual "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">void "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">turnOn"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"params"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">() = "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"number"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">0; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"function"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">virtual "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">void "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">turnOff"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"params"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">() = "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"number"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">0; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">}; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// GPIO LED 实现 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">class "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title class_"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">GPIO_LED : "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">public LED { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">private: "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int pin; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">public: "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"built_in"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">GPIO_LED("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int gpioPin) : "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"built_in"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">pin(gpioPin) {} "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"function"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">void "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">turnOn"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"params"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">() "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">override { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// GPIO设置为高电平 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> } "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"function"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">void "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">turnOff"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"params"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">() "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">override { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// GPIO设置为低电平 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> } "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">};

2. Platform Device 平台总线模型

随着硬件设备的复杂性增加<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，需要一种更系统化的方式来管理设备驱动和硬件资源<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。平台设备总线<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（Platform Bus<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）将所有硬件设备抽象为平台设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（Platform Devices<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）和平台驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（Platform Drivers<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>。这种抽象使得驱动开发者不必关心具体的硬件细节<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，而是通过一套标准的接口来管理设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

通过这种模型<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，驱动开发者可以集中精力在设备的具体操作上<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，而不需要处理复杂的总线协议或硬件初始化流程<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。平台总线为驱动提供了标准的生命周期管理和资源访问方式<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

思想<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

• 平台设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：将硬件设备抽象为平台设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（Platform Device<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>，这些设备通过平台总线<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（Platform Bus<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）连接到系统中<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 平台驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：相应地<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，驱动程序也被抽象为平台驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（Platform Driver<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>，它们通过平台总线匹配到相应的设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

技术细节<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

• 在Linux内核中<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，struct platform_device 和 struct platform_driver 是关键数据结构<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 设备和驱动通过设备树或者是硬编码的方式注册到平台总线上<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 使用总线驱动框架<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（如I2C<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>、SPI等<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）来进一步抽象硬件接口<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"highlight c"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"code"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 定义平台设备的结构 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">platform_device { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 设备的名称"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">，用于匹配驱动 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">const "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">char *name; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int id; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">bool id_auto; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">device "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">dev; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> u32 num_resources; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 指向资源数组的指针"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">，资源包括内存区域"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">、IRQ等 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">resource *"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">resource; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">/* 其他字段省略 */ "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">}; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 定义平台驱动的结构 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">platform_driver { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 探测函数"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">，当设备被发现时调用"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">，负责初始化设备 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int (*probe)("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct platform_device *); "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 移除设备时调用"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">，用于清理资源 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int (*remove)("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct platform_device *); "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">void (*shutdown)("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct platform_device *); "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int (*suspend)("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct platform_device *, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">pm_message_t state); "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int (*resume)("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct platform_device *); "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 内嵌的通用设备驱动结构"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">，包含了驱动信息如驱动名称"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">、所有者等 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">device_driver "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">driver; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">const "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">platform_device_id *"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">id_table; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">/* 其他字段省略 */ "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">};

例子<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：同上<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，LED连接到GPIO<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

• 平台设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：定义一个平台设备来代表这个LED<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"highlight c"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"code"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">static "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">platform_device "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">led_device = { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .name = "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"string"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"led", "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .id = "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"number"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">-1, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .dev = { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .platform_data = &gpio_pin_number, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 假设这个GPIO引脚号作为平台数据 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> }, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">};

• 平台驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：编写一个平台驱动来操作这个LED<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"highlight c"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"code"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">static "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">platform_driver "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">led_driver = { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .probe = led_probe, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .remove = led_remove, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .driver = { "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .name = "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"string"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"led", "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> .owner = THIS_MODULE, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> }, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">}; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">static "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title function_"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">led_probe"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"params"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct platform_device *pdev) "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">{ "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 获取设备的GPIO引脚信息并初始化LED "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">return "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"number"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">0; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">} "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">static "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title function_"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">led_remove"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"params"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct platform_device *pdev) "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">{ "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 清理LED相关的资源 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">return "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"number"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">0; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">}

技术细节<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

• 通过平台设备和平台驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，系统可以自动匹配设备和驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。led_probe 函数在匹配成功后初始化LED<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，led_remove 函数在设备卸载时清理资源<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

匹配过程

平台设备与驱动的匹配过程大致如下<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

1. 设备注册<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

   • 当内核启动或模块加载时<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，平台设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（struct platform_device<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）被注册到平台总线<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（platform_bus<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）上<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

2. 驱动注册<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

   • 平台驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（struct platform_driver<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）也需要注册到平台总线上<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

3. 设备树解析<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

   • 如果使用设备树<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，内核会解析设备树文件<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（.dts或.dtb<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>，从中获取设备信息<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，并创建相应的平台设备实例<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

4. 匹配尝试<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

   • 内核尝试将注册的驱动与平台总线上的设备进行匹配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
   • 匹配过程主要遵循以下顺序<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：
     • 设备树匹配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：优先尝试使用设备树匹配规则<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，检查设备的compatible属性与驱动的of_match_table是否匹配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
     • ID匹配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：如果设备树匹配失败<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，尝试使用设备ID匹配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
     • 名称匹配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：最后<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，尝试使用驱动和设备的名称匹配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

5. 成功匹配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

   • 一旦找到匹配的设备和驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，内核会调用驱动的probe方法<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。probe方法将接收到匹配的struct device<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（实际上是一个struct platform_device<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>，驱动可以在这个方法中初始化设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

6. 资源分配<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

   • 在probe方法中<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，驱动可以访问设备的资源<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（如IO内存<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>、IRQ等<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>，这些资源通常是通过设备树或平台设备注册时提供的<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

7. 设备绑定<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

   • 如果probe方法成功<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，设备将绑定到驱动<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，设备现在可以正常工作<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

8. 失败处理<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

   • 如果匹配失败或probe方法失败<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，内核会记录错误信息<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，驱动将不会绑定到设

3. 设备树<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（Device Tree<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）

背景<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：
随着SoC<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（System on Chip<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）的发展<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，硬件配置变得极为复杂和多样化<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，硬编码的方式变得难以维护<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

思想<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

• 解耦硬件描述<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：将硬件的描述从内核代码中分离出来<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，形成独立的设备树描述文件<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（.dts, .dtsi<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>。
• 动态配置<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：设备树提供了一种动态的<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>、可配置的方式来描述系统硬件<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

技术细节<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

• 设备树使用一种类似JSON的格式来描述硬件结构<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，包括节点<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（nodes<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）表示设备<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，属性<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（properties<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）表示设备的特性<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 内核中的设备树编译器<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（dtc<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）将设备树源文件编译成二进制格式<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（DTB<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>，内核启动时加载DTB来配置硬件<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 驱动程序通过设备树中的信息来获取设备的地址<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>、IRQ等信息<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，实现即插即用<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

例子<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：同上<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，一个LED连接到GPIO<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

• 设备树描述<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

  "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"highlight dts"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">

  "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"code"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title class_"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">/ "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"punctuation"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">{ "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title class_"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">leds "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"punctuation"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">{ "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"attr"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">compatible "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"operator"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">= "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"string"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"gpio-led""bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"punctuation"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"attr"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">gpios "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"operator"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">= "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"params"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"><"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"variable"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">&gpio "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"number"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">17 GPIO_ACTIVE_HIGH>"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"punctuation"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 假设LED连接到GPIO17 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"attr"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">label "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"operator"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">= "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"string"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"led""bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"punctuation"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"punctuation"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">}; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"punctuation"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">};

• 驱动代码<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：现在驱动可以从设备树中获取LED的配置信息<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"highlight c"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">

"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"code"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">static "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title function_"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">led_probe"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"params"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">("bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct platform_device *pdev) "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">{ "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"class"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">struct "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">device_node *"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"title"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">node = pdev->dev.of_node; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"type"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">int gpio; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">if (of_property_read_u32(node, "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"string"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">"gpios", &gpio)) "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">return -ENODEV; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"comment"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">// 使用GPIO进行LED操作 "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"> "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"keyword"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">return "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"number"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">0; "bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">"line"bd bd-beg">"bd-box"bd bd-beg">">"bd bd-beg">">}

设备树描述了硬件配置<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，驱动通过解析设备树节点来获取硬件信息<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“>（如GPIO引脚号<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>）<h-char class=“bd bd-beg“>。这种方式使得硬件配置与内核代码解耦<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，硬件变化只需修改设备树文件即可<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

进化意义<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：

• 从面向对象到平台总线模型<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，再到设备树的演变过程中<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，硬件资源的管理变得越来越抽象和灵活<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。每个阶段都使得驱动开发和维护更加高效<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，减少了对具体硬件的依赖<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，增强了系统的可移植性和可维护性<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。通过LED点灯这个简单的例子<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，我们可以看到这种进化带来的实际好处<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>：从最初的硬编码<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，到设备树的动态配置<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，使得系统对硬件变化的适应性大大增强<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 从面向对象到平台总线模型<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，再到设备树<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，硬件资源的管理和配置变得越来越抽象和通用<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，减少了对具体硬件的依赖<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，提升了系统的可移植性和可维护性<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。
• 设备树的引入大大简化了内核的硬件描述方式<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，使得硬件支持的添加和修改变得更加灵活和高效<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。

这个过程展示了操作系统在面对越来越复杂的硬件环境时<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>，不断优化和抽象硬件管理方法的演进过程<span class=<h-char class=“bd bd-beg“>“bd-box<h-char class=“bd bd-beg“>“><h-char class=“bd bd-beg“>。