NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
{
  DriverObject->MajorFunction[IRP_MJ_CREATE] = XXXXDispatchCreate;
  DriverObject->MajorFunction[IRP_MJ_CLOSE]  = XXXXDispatchClose;
  DriverObject->MajorFunction[IRP_MJ_PNP]    = XXXXDispatchPnp;     
  DriverObject->MajorFunction[IRP_MJ_POWER]  = XXXXDispatchPower;
  DriverObject->MajorFunction[IRP_MJ_READ]   = XXXXDispatchRead;
  DriverObject->MajorFunction[IRP_MJ_WRITE]  = XXXXDispatchWrite;
  DriverObject->MajorFunction[IRP_MJ_DEVICE_CONTROL] = XXXXDispatchDeviceControl;
  DriverObject->DriverUnload = XXXXUnload;
  DriverObject->DeviceExtension->AddDevice = XXXXAddDevice;
}

The DriverEntry gets pointer to its own driver object (DriverObject).DriverEntry initializes entry points for other routines of the driver and stores their pointers in the DriverObject. DriverEntry also initializes DriverUnload routine and AddDevice routine.

AddDevice:

Syntax:

NTSTATUS XXXXAddDevice(PDRIVER_OBJECT DriverObject, PDEVICE_OBJECT DeviceObject)
{
//.....
}

DriverUnload :

Syntax:

NTSTATUS XXXXUnload(PDRIVER_OBJECT DriverObject)
{
//…………..
}

Apart from DriverUnload and AddDevice rest all routines initialised in DriverEntry share same signature.

NTSTATUS  XXXX(PDEVICE_OBJECT DeviceObject, PIRP Irp);

IRP_MJ_CREATE :

Syntax:

NTSTATUS  XXXXDispatchCreate(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
//…………
}

All dispatch routines must make a call to the function IoGetCurrentIrpStackLocation to get driver’s associate stack location. Also all dispatch routines must to fill out the PIRP and complete the routine through IoCompleteRequest.

PIRP can be filled as below:

Irp->IoStatus.Status = STATUS_SUCCESS;
Irp->IoStatus.Information = 0;
IoCompleteRequest( Irp,IO_NO_INCREMENT);

IRP_MJ_CLOSE :

Syntax:

NTSTATUS  XXXXDispatchClose(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
//…………
}

IRP_MJ_PNP:

Syntax

NTSTATUS  XXXXDispatchPnp(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
//…………
}

Plug-n-Play (PNP) is acombination of hardware and softawre support that enables a computer to recognize and adapt to new hardware configuration change with little or no user intervension (i.e) user can add or remove devices at run time.

PNP's main responsibilities:

• Automatic detection of hardware installation changes
  
• Loading appropriate drivers during run time.

When a device is added to the system at run time some of the steps to be taken care of can be describe briefly as:

• The user plugs in the device in a free slot
  
• Function driver on the bus determines that there is a new device on the bus
  
• Function driver notifies the PNP Manager about the new device addition
  
• PNP manager send an IRP and the function driver of the bus handles the IRP and creates the PDO for the new device.
  
• PNP manager gathers the information about the device through various IRPs and stores the information in the registry.
  
• User mode setup components call kernel mode to help them call AddDevice routine.
  
• PNP manager helps call the drivers DriverEntry and attaches the device to the stack
  
• Resources necessary for the device are added and the device is started.

PnP has minor functions to support each PnP request accordingly. Few of the required function codes are:

IRP_MN_START_DEVICE
IRP_MN_QUERY_REMOVE_DEVICE
IRP_MN_REMOVE_DEVICE
IRP_MN_CANCEL_REMOVE_DEVICE
IRP_MN_QUERY_STOP_DEVICE
IRP_MN_ STOP_DEVICE
IRP_MN_CANCEL_STOP_DEVICE
IRP_MN_SURPRISE_REMOVAL

PNP Manager sends this IRP after it has assigned hardware resources to the device.The device may have been recently enumerated and is being started for the very first time or is restarting after being stopped. It an also be sent when driver currently in use requires new set of resources.

IRP_MN_QUERY_REMOVE_DEVICE:

This IRP is sent to query if the device if the device can be removed with out disturbing the system. In response to this IRP drivers inform whether the device can be removed or not.

IRP_MN_REMOVE_DEVICE:

This IRP is used to remove to device’s software representations like device object from the system. This IRP is called when the device is removed in orderly fashion or plugged out with out prior notification or when the driver needs an update.

IRP_MN_CANCEL_REMOVE_DEVICE:

This IRP is sent to inform the driver that the device will not be removed from the system. The status prior to the IRP_MN_QUERY_REMOVE_DEVICE will be restored in this case.

IRP_MN_QUERY_STOP_DEVICE:

This IRP is sent to query whether a device can be stopped to rebalance the resources. In response to this IRP the device informs if it is safe to stop the device or not.

IRP_MN_ STOP_DEVICE:

This IRP is sent to stop the device to reconfigure the hardware resources. In response to this IRP driver stops the device and releases the hardware resources being used by the device.

IRP_MN_CANCEL_STOP_DEVICE:

This IRP is sent to inform the driver that the device will not be stopped for rebalancing of the resources. In response to this IRP the driver must return the device to the started state.

IRP_MN_SURPRISE_REMOVAL:

This IRP is sent to the drivers for a device to inform that the device is no longer available for I/O operations. This may happen for reasons like:-

• The bus has hot-plug notification and it notifies the device's parent bus driver that the device has disappeared.
  
• When the bus is enumerated the surprise removed device will not be there on the bus.

In response to this IRP, Some of the steps to be taken care of are:

• Ensure that the device is not available
  
• Release the device’s hardware resources
  
• Notify the power manager with PoSetPowerState and power down the bus slot of the device if possible
  
• Prevent further I/O operations and fail the outstanding ones.
  
• Process subsequent cleanup and close operations to the device.
  
• After this IRP succeeds IRP_MN_REMOVE_DEVICE must be called.

IRP_MJ_POWER :

Syntax

NTSTATUS  XXXXDispatchPower(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
//…………
}

IRP_MN_POWER_SEQUENCE
IRP_MN_SET_POWER
IRP_MN_WAIT_WAKE
IRP_MN_QUERY_POWER

IRP_MN_POWER_SEQUENCE:

This IRP is for optimization and is sent to determine whether its device actually entered a specific power state or not. IRP returns the power sequence values for the device.

IRP_MN_SET_POWER:

This IRP is sent to notify the drivers of the change to the system power state or to change the power state of a device for which the power manager is performing idle detection. PoRequestPowerIrp must be called to send this IRP.

IRP_MN_WAIT_WAKE:

This IRP is used to awaken a system/device from sleep state.

IRP_MN_QUERY_POWER:

This IRP is sent to query whether the system power state or the device power state can be changed.PoRequestPowerIrp must be called to send this IRP.

IRP_MJ_DEVICE_CONTROL :

Syntax

NTSTATUS  XXXXDeviceControl(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
//…………
}

Every driver whose device objects belong to a particular device type and has a set of system-defined I/O control codes (IOCTLs) support this IRP. A driver receives this I/O control code because user-mode thread has called the Microsoft Win32 DeviceIoControl function, or a higher-level kernel-mode driver has set up the request. On receipt of a device I/O control request for most I/O control codes, device drivers transfer a small amount of data to or from the buffer.

IRP_MJ_READ :

Syntax

NTSTATUS  XXXXDispatchRead(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
//…………
}

IRP_MJ_WRITE :

Syntax

NTSTATUS  XXXXDispatchWrite(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
//…………
}

References:

Windows® 2000 Device Driver Book: A Guide for Programmers, Second Edition
MSDN
___________________
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Posted by: Harisha Nelapatla.    # 5:31 PM Tweet