CE5.0 驱动程序：设备管理器的源码分析
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 WINAPI WinMain(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.
