[开发工具]Windows驱动开发（三）一个WDF入门实例

上一章大概介绍了WDM/WDF的IOControl，

链接：https://blog.csdn.net/o0xwh_93150o/article/details/104234021

鸽太久了，刚好闲下来，就把这个实例入门篇给补了吧。话不多说，先上代码。

DriverEntry例程：

NTSTATUS

DriverEntry(

????IN PDRIVER_OBJECT ?DriverObject,

????IN PUNICODE_STRING RegistryPath) {

????WDF_DRIVER_CONFIG config;

????NTSTATUS status = STATUS_SUCCESS;

????WDF_OBJECT_ATTRIBUTES attributes;

????//

????// Initialize WPP Tracing

????//

????WPP_INIT_TRACING( DriverObject, RegistryPath );

????TraceEvents(TRACE_LEVEL_INFORMATION, TRACE_DRIVER, "%!FUNC! Entry");

????

????//

????// Register a cleanup callback so that we can call WPP_CLEANUP when

????// the framework driver object is deleted during driver unload.

????//

????WDF_OBJECT_ATTRIBUTES_INIT(&attributes);

????attributes.EvtCleanupCallback = Spw_PCIeEvtDriverContextCleanup;

????WDF_DRIVER_CONFIG_INIT(&config, Spw_PCIeEvtDeviceAdd);

????status = WdfDriverCreate(DriverObject,

?????????????????????????????RegistryPath,

?????????????????????????????&attributes,

?????????????????????????????&config,

?????????????????????????????WDF_NO_HANDLE);

????if (!NT_SUCCESS(status)) {

????????TraceEvents(TRACE_LEVEL_ERROR, TRACE_DRIVER, "WdfDriverCreate failed %!STATUS!", status);

????????WPP_CLEANUP(DriverObject);

????????return status;

????}

??

????TraceEvents(TRACE_LEVEL_INFORMATION, TRACE_DRIVER, "%!FUNC! Exit");

????return status;

}

每一个WDF驱动必须有一个DriverEntry例程，当操作系统监测到有硬件设备插入时，就会找到对应的DriverEntry例程，DriverEntry例程需要完成以下这些功能：

1. 注册WDF的DeviceAdd回调函数，这是WDF驱动与NT驱动最大的不同之一
2. 创建一个驱动对象，用于向框架注册我们的驱动程序

在WDF中，真正被我们当作初始化的函数，变成了DeviceAdd，所以可以把相关的初始化行为全部丢在DeviceAdd中。

DeviceAdd例程：

NTSTATUS

Spw_PCIeEvtDeviceAdd(_In_ ???WDFDRIVER ??????Driver,

?????????????????????_Inout_ PWDFDEVICE_INIT DeviceInit) {

????NTSTATUS status = STATUS_SUCCESS;

????WDF_PNPPOWER_EVENT_CALLBACKS pnpPowerCallbacks;

????WDF_OBJECT_ATTRIBUTES ??deviceAttributes;

????WDFDEVICE device;

????PDEVICE_CONTEXT deviceContext;

????WDFQUEUE queue;

????WDF_IO_QUEUE_CONFIG ???queueConfig;

????UNREFERENCED_PARAMETER(Driver);

????PAGED_CODE();

????WdfDeviceInitSetIoType(DeviceInit, WdfDeviceIoDirect);

????//When the I/O manager sends a request for buffered I/O, the IRP contains an internal copy of the caller's buffer

????//rather than the caller's buffer itself. The I/O manager copies data from the caller's buffer to the internal buffer

????//during a write request or from the internal buffer to the caller's buffer when the driver completes a read

????//request.

????//The WDF driver receives a WDF request object, which in turn contains an embedded WDF memory object.

????//The memory object contains the address of the buffer on which the driver should operate.

????

????//初始化即插即用和电源管理例程配置结构

????WDF_PNPPOWER_EVENT_CALLBACKS_INIT(&pnpPowerCallbacks);

????//设置即插即用基本例程

????pnpPowerCallbacks.EvtDevicePrepareHardware = Spw_PCIeEvtDevicePrepareHardware;

????pnpPowerCallbacks.EvtDeviceReleaseHardware = Spw_PCIeEvtDeviceReleaseHardware;

????pnpPowerCallbacks.EvtDeviceD0Entry = Spw_PCIeEvtDeviceD0Entry;

????pnpPowerCallbacks.EvtDeviceD0Exit = Spw_PCIeEvtDeviceD0Exit;

????//注册即插即用和电源管理例程

????WdfDeviceInitSetPnpPowerEventCallbacks(DeviceInit, &pnpPowerCallbacks);

????

????WDF_OBJECT_ATTRIBUTES_INIT_CONTEXT_TYPE(&deviceAttributes, DEVICE_CONTEXT);

????//deviceAttributes.EvtCleanupCallback = Spw_PCIeEvtDriverContextCleanup;

????//

????// Set WDFDEVICE synchronization scope. By opting for device level

????// synchronization scope, all the queue and timer callbacks are

????// synchronized with the device-level spinlock.

????//

????deviceAttributes.SynchronizationScope = WdfSynchronizationScopeDevice;

????status = WdfDeviceCreate(&DeviceInit, &deviceAttributes, &device);

????if (!NT_SUCCESS(status)) {

????????return status;

????}

????deviceContext = GetDeviceContext(device);

????//用default初始化default 队列，用另一个初始化非default队列

????WDF_IO_QUEUE_CONFIG_INIT(&queueConfig,

?????????????????????????????WdfIoQueueDispatchSequential);

????queueConfig.EvtIoDeviceControl = Spw_PCIeEvtIoDeviceControl;

????status = WdfIoQueueCreate(device, &queueConfig, WDF_NO_OBJECT_ATTRIBUTES, &queue);

????if (!NT_SUCCESS(status)) { ???

????????return status;

????}

????//非默认队列，必须指定要分发的I/O请求类型

????//The WdfDeviceConfigureRequestDispatching method causes the framework to queue a specified type of I/O requests to a specified I/O queue.

????status = WdfDeviceConfigureRequestDispatching(device,

??????????????????????????????????????????????????queue,

??????????????????????????????????????????????????WdfRequestTypeDeviceControl);

????if (!NT_SUCCESS(status)) {

????????return status;

????}

????//创建驱动程序接口与应用程序通信

????status = WdfDeviceCreateDeviceInterface(device,

????????????????????????????????????????????(LPGUID)&GUID_DEVINTERFACE_Spw_PCIe,

????????????????????????????????????????????NULL // ReferenceString);

????if (!NT_SUCCESS(status)) {

????????return status;

????}

????return status;

}

此例程主要做了下面几件重要的事情：

1. 创建初始化设备对象及其上下文
2. 若该WDF驱动为支持PnP的，则要注册PnP相关的一系列回调函数
3. 若该驱动需要处理IO，则需要配置一个消息队列，注册处理例程以及制定IO请求类型等等
4. 若该驱动需要与其他程序进行交互，则可以注册一个GUID接口用于通信，当然，也可以使用符号链接的形式。

在PnP的管理例程注册部分，可以看到几个典型的回调，即PrepareHardware，ReleaseHardware，DeviceEntry以及DeviceExit。

PrepareHardware以及ReleaseHardware关系着你的硬件是否可以获得Windows分配的资源，而在PrepareHardware里面，你需要去实现内存资源，内存地址映射，IO端口映射以及CPU中断资源的分配等等。

在WDF中，给硬件分配资源的大致流程如下：

1. 当插入一个PnP设备时，总线枚举驱动识别该设备
2. 调用总线驱动的DeviceResourceQuery，创建资源列表
3. 调用总线驱动的DeviceResourceRequirementQuery，创建资源需求列表
4. 由PnP管理器来匹配驱动，随后申请必要的资源，将信息发送给驱动程序
5. 当你的设备最终进入工作预备状态时，前面写的PrepareHardware即生效
6. 之后进入到DeviceEntry例程，通常，DeviceEntry例程并需要额外处理事务

WDF的很多Sample之前在微软的msdn?sample里面都有，包含了各种各样的硬件设备驱动，过滤驱动，枚举驱动等等，可惜不知道为什么被微软下架了。。。不过好在万能的百度上还是能找得到的，不过这里面的sample都没有去实现具体的功能，只是阐述了一个个驱动开发的模型，虽然代码量很小，但这已经是我们能看到的最好的例子了，熟悉了之后，自己去具体开发符合你需求的功能驱动就不那么困难。

后面的话，因为这几年做的很多实际的驱动，会不定期写一些笔记，当然，不在仅限于小端口驱动了～