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CE5.0 驱动程序:设备管理器的源码分析

 
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系统下面许多设备,比如键盘,串口,触摸屏,硬盘......这些设备什么时候被系统使用的?这些设备怎样被系统使用的?加载过程是怎么样的?设备如何加入系统协同工作的?为什么系统能检测到并使用即插即用的设备(如usb鼠标)?系统是怎么控制设备的电源的?

CE管理设备的程序叫做DEVICE.EXE,这是一个独立的用户级进程,它主要负责跟踪,维护系统的设备信息并对设备资源进行调配.设备管理器包括即插即用设备管理,电源管理,io资源管理等等.

结构示意图:

目录树:c:/WINCE500/PRIVATE/WINCEOS/COREOS/DEVICE/

[DEVCORE]设备管理器的核心代码部分.

Devapi.c

Devcore.c

Devfile.c

Devfsd.c

Devload.c

Devpnp.c

Celogdev.h

[DEVMAIN]程序入口点.

devmain.c

[INC]头文件

Devmgrif.h

Devmgrp.h

Devzones.h

Iormif.h

Pmif.h

[IORM]io资源管理

Iorm.c

[NOPMIF]电源管理模块接口(这里是不要电源管理模块的'空'接口)

Nopmif.c

[PMIF]电源管理模块接口

Pmif.c

源码分析按照先后执行顺序来分析源代码.)

在[DEVMAIN]中有一个devmain.c的代码,这是device.exe的入口点.如同标准c的main()函数所在,因为是windows所以入口点是WinMain()这样的函数.在WinMain()内没有其他内容,只调用了StartDeviceManager()这个函数.

int WINAPIWinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPWSTR lpCmdLine, int nCmdShow)

{

int status;

status = StartDeviceManager(hInst, hPrevInst, lpCmdLine, nCmdShow);

return status;

}

前面WinMain()调用的StartDeviceManager()函数位于devcore.c. 这个函数初始化设备管理器,电源管理器,IO资源管理,然后启动设备管理器,开始负责设备驱动的加载和卸载工作.

int WINAPI

StartDeviceManager(HINSTANCE hInst, HINSTANCE hPrevInst, LPWSTR lpCmdLine, int nCmShow)

{

HINSTANCE hCeddkDll;

HANDLE hEvent;

if (IsAPIReady(SH_DEVMGR_APIS)) {

return 0;

}

DEBUGREGISTER(NULL);

DEBUGMSG(ZONE_BOOTSEQ, (TEXT("DEVICE: Starting boot phase 1/n")));

// PHASE 1

g_BootPhase = 1; //用一个全局变量来表示现在处于启动的哪个阶段.一共有3个阶段.

// 0表示还没有开始启动;1表示在搜索注册表的值;2表示在加载设备;

// 3表示已经开始正常运行了.

InitOOMSettings(); // 初始化OOM.

InitializeListHead(&g_DevChain);// 初始化常规状态设备列表

InitializeListHead(&g_ActivatingDevs); // 初始化激活的已经注册的设备列表

InitializeListHead(&g_DyingDevs); // 初始化消亡状态的设备列表

InitializeListHead(&g_CandidateDevs); // 初始化正在加载的设备驱动列表.

g_hCleanEvt = CreateEvent(NULL, FALSE, FALSE, NULL);

g_hDevApiHandle = CreateAPISet("WFLD", NUM_FDEV_APIS, FDevApiMethods, FDevApiSigs);// 向系统注册api

g_hDevFileApiHandle = CreateAPISet("W32D", NUM_FAPIS, DevFileApiMethods, DevFileApiSigs); // 向系统注册api

RegisterAPISet(g_hDevFileApiHandle, HT_FILE | REGISTER_APISET_TYPE);

InitializePnPNotifications(); // 这个程序将调用StartDeviceNotifyThread()

// 这将启动一个线程.它的具体实现在devpnp.c文件中.

InitializeCriticalSection(&g_devcs); // 初始化临界区.

ResourceInitModule(); // 初始化一个全局变量gdwMaxDenseResources

// 根据注册表来初始化设备管理资源

ResourceInitFromRegistry(TEXT("Drivers//Resources"));

SetPowerOffHandler((FARPROC) DevMgrPowerOffHandler);

RegisterAPISet(g_hDevApiHandle, SH_DEVMGR_APIS);

InitDeviceFilesystems();

// Indicate that the device manager is up and running

hEvent = OpenEvent(EVENT_ALL_ACCESS, FALSE, _T("SYSTEM/DevMgrApiSetReady"));

DEBUGCHK(hEvent != NULL);

if (hEvent != NULL) {

SetEvent(hEvent);//设置一个全局事件.通知别的程序设备管理器api已经准备好了.

// 在其他的应用里面,使用设备管理器api前,如果希望确认设备管理器

// 的api已经注册好,它会等待这样一个事件.

CloseHandle(hEvent);

}

// Calibrate stall counter that is used for StallExecution

// 以下代码调用ceddk.dll里面的fnCalibrateStall()函数.

hCeddkDll = LoadLibrary (TEXT("ceddk.dll"));

if (NULL != hCeddkDll) {

pCalibrateStallFn fnCalibrateStall = (pCalibrateStallFn)/

GetProcAddress(hCeddkDll, TEXT("CalibrateStallCounter"));

if (!fnCalibrateStall) {

DEBUGMSG(ZONE_BOOTSEQ,(L"GetProcAddress failed on ceddk.dll/r/n"));

FreeLibrary(hCeddkDll);

}

else {

fnCalibrateStall();

}

}

// Call the power manager initialization entry point

PM_Init(); // 初始化电源管理模块.电源管理模块是一个pm.dll.它也被device.exe调用.这里// 暂时不打算涉及电源管理部分.简单来说:在PM_Init()函数里面会启动3个线程,

// PnpThreadProc,ResumeThreadProc, ActivityTimersThreadProc

// 它们各自负责监控即插即用,Resume,和激活定时器

PM_SetSystemPowerState(NULL, POWER_STATE_ON, POWER_FORCE);//设置系统电源开.

// See if we are going to have two boot phases

// 根据注册表内容,决定采用怎样的加载过程.

// 如果存在SYSTEM/BootPhase1.分2个步骤来加载:

// 先DevloadInit()加载一次,然后等待通知后,继续调用InitDevice()加载.

// 如果没有SYSTEM/BootPhase1,则调用DevloadInit()一次完成.

// 也许是满足一些需要2次加载设备的情况,所以留下这个功能.

hEvent = OpenEvent(EVENT_ALL_ACCESS, FALSE, _T("SYSTEM/BootPhase1"));

if (hEvent != NULL) {

// Load phase 1 drivers from the boot registry

DevloadInit(); // 加载设备.DevloadInit()函数位于devload.c,它首先删除注册表里面

// Device/Active,然后调用InitDevices()函数加载设备驱动.

// Signal boot phase 1 complete

SetEvent(hEvent); // 发出通知,阶段1已经完成.

CloseHandle(hEvent);

// Wait for phase 2 of the boot to begin

// 等待通知后进入阶段2

hEvent = OpenEvent(EVENT_ALL_ACCESS, FALSE, TEXT("SYSTEM/BootPhase2"));

DEBUGCHK(hEvent);

if (hEvent) {

DEBUGMSG(ZONE_BOOTSEQ, (TEXT("DEVICE: Started, waiting for boot phase 2/r/n")));

WaitForSingleObject(hEvent, INFINITE);

CloseHandle(hEvent);

}

// Load any new drivers from the persistent registry.Since the

// registry may have changed, update the power state for any devices

// that need it.

DEBUGMSG(ZONE_BOOTSEQ, (TEXT("DEVICE: Second-phase driver load/r/n")));

g_BootPhase = 2;

PM_SetSystemPowerState(NULL, POWER_STATE_ON, POWER_FORCE);

InitDevices(NULL); // DevInit()加载会先清空注册表Acitve下的内容,

// 第二次加载不能把前面一次的清空,所以这里不能用DevInit().

DEBUGMSG(ZONE_BOOTSEQ, (TEXT("DEVICE: Startup sequence complete/r/n")));

SignalStartedUsingReg(); // SignalStarted call with the right args

} else {

DEBUGMSG(ZONE_BOOTSEQ, (TEXT("DEVICE: No boot registry - skipping to boot phase 2/n")));

g_BootPhase = 2;

DevloadInit();

SignalStarted(_wtol(lpCmdLine));

}

// Boot phase 3 isn't any different from phase 2; just marks that we got here.

DEBUGMSG(ZONE_BOOTSEQ,

(TEXT("DEVICE: Finished loading primary drivers - entering boot phase 3/n")));

g_BootPhase = 3; // 进入阶段3,同时也标志设备管理器开始运行了.

CELOG_DeviceFinished (); // 记录日志.

while (1) {

WaitForSingleObject(g_hCleanEvt, INFINITE);

// check for auto-deregister devs first as they may end up queuing

// themselves on the dying devs list

ProcessAutoDeregisterDevs();

ProcessDyingDevs();

ProcessDyingOpens();

}

return 1;// should not ever be reached

}

加载设备的函数,DevloadInit()事实上也是调用InitDevices来实现,只不过事先清空了Acitve下的注册表内容

void DevloadInit(void)

{

DEBUGMSG(ZONE_INIT, (TEXT("DEVICE!DevloadInit/r/n")));

#define PHASE_1_BUSNAME TEXT("BuiltInPhase1")

//

// Delete the HLM/Drivers/Active key since there are no active devices at

// init time.

// 清空注册表Active下的内容.

RegDeleteKey(HKEY_LOCAL_MACHINE, s_ActiveKey);

#ifdef DEBUG

v_NextDeviceNum = 0xFFFFFFF0;// expect wraparound

#else// DEBUG

v_NextDeviceNum = 1;

#endif// DEBUG

g_bSystemInitd = FALSE;

InitDevices(PHASE_1_BUSNAME);

}

InitDevices(LPCTSTR lpBusName )

{

HKEY RootKey;

DWORD status;

DWORD ValType;

DWORD ValLen;

TCHAR RootKeyPath[REG_PATH_LEN];

TCHAR BusName[DEVKEY_LEN];

REGINI reg[1];

DWORDdwRegCount=0;

//

// Open HLM/Drivers key

//打开注册表HLM/Drivers.

status = RegOpenKeyEx(

HKEY_LOCAL_MACHINE,

DEVLOAD_DRIVERS_KEY, //DEVLOAD_DRIVERS_KEY= "Drivers"

0,

0,

&RootKey);

if (status != ERROR_SUCCESS) {

DEBUGMSG(ZONE_ROOT|ZONE_ERROR,

(TEXT("DEVICE!InitDevices RegOpenKeyEx(%s) returned %d./r/n"),

DEVLOAD_DRIVERS_KEY, status));

return;

}

//

// Look for root key value; if not found use current Root Key as default,

// otherwise open new root key

// 查询注册表中 RootKey的值,一般这个值是Devices/BuildIn.将查询的值保存到RootKeyPath.

// 如果没有指定,则使用Devices来替代.

ValLen = sizeof(RootKeyPath);

status = RegQueryValueEx(

RootKey,

DEVLOAD_ROOTKEY_VALNAME, //DEVLOAD_ROOTKEY_VALNAME =RootKey

NULL,

&ValType,

(PUCHAR)RootKeyPath,

&ValLen);

RootKeyPath[ARRAYSIZE(RootKeyPath) - 1] = 0;

if (status != ERROR_SUCCESS) {

// Root key value not found, thus root key is Drivers

_tcscpy(RootKeyPath, DEVLOAD_DRIVERS_KEY); // 没有找到,使用Devices来替代.

}

// Close previous root key

RegCloseKey(RootKey);

DEBUGMSG(1,

(L"DEVICE!InitDevices: Root Key is %s./r/n",

RootKeyPath));

// 为ActiveDeviceEx准备参数reg. 如果输入参数lpBusName指定了,则从参数lpBusName获得,

// 否则从注册表中读取.

if (lpBusName!=NULL) {

reg[0].lpszVal = DEVLOAD_BUSNAME_VALNAME;

reg[0].dwType= DEVLOAD_BUSNAME_VALTYPE;

reg[0].pData= (PBYTE) lpBusName ;

reg[0].dwLen= (_tcslen( lpBusName ) + 1) * sizeof(TCHAR);

dwRegCount = 1;

}

else {

status = RegOpenKeyEx( HKEY_LOCAL_MACHINE, RootKeyPath,0,0, &RootKey);

if (status == ERROR_SUCCESS ) {

ValLen = sizeof( BusName);

status = RegQueryValueEx(

RootKey,

DEVLOAD_BUSNAME_VALNAME,

NULL,

&ValType,

(PUCHAR)BusName,

&ValLen);

if (status == ERROR_SUCCESS && ValType==DEVLOAD_BUSNAME_VALTYPE) {

// We found Bus Name. This is new bus driver model. So we use new format.

BusName[DEVKEY_LEN-1] = 0;

reg[0].lpszVal = DEVLOAD_BUSNAME_VALNAME;

reg[0].dwType= DEVLOAD_BUSNAME_VALTYPE;

reg[0].pData= (PBYTE)BusName;

reg[0].dwLen=ValLen;

dwRegCount = 1;

}

// Close previous root key

RegCloseKey(RootKey);

}

}

// Someday we'll want to track the handle returned by ActivateDevice so that

// we can potentially deactivate it later. But since this code refers only to

// builtin (ie, static) devices, we can just throw away the key.

if (dwRegCount)

ActivateDeviceEx(RootKeyPath,reg,dwRegCount,NULL);

else

ActivateDevice(RootKeyPath, 0);

}// InitDevices

至此,已经明确了系统是通过InitDevice()来加载驱动,更具体的InitDevice()会调用ActivateDeviceEx()来加载驱动,但是,这里只加载了一个驱动啊,难道系统就只加载一次?

这个唯一被加载的驱动是BusEnum.dll(在CE4.2是RegEnum.dll)这个驱动位于public下,它枚举了BuiltIn下所有的设备,逐个加载,并在Active下记录成功加载的设备.

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