EVT_SPB_CONTROLLER_UNLOCK callback function (spbcx.h)

Artikel
10/25/2021

An SPB controller driver's EvtSpbControllerUnlock event callback function unlocks the SPB controller, which was locked by a previous call to the EvtSpbControllerLock event callback function.

Syntax

EVT_SPB_CONTROLLER_UNLOCK EvtSpbControllerUnlock;

void EvtSpbControllerUnlock(
  [in] WDFDEVICE Controller,
  [in] SPBTARGET Target,
  [in] SPBREQUEST UnlockRequest
)
{...}

Parameters

[in] Controller

A WDFDEVICE handle to the framework device object that represents the SPB controller.

[in] Target

An SPBTARGET handle to the target for this I/O request. The target is a peripheral device or port that is attached to the bus. The SPB framework extension (SpbCx) previously assigned this handle to the target in the EvtSpbTargetConnect callback that opened the connection to the target.

[in] UnlockRequest

An SPBREQUEST handle to an I/O control request to unlock the controller. Your SPB controller driver must complete this request either by performing the requested operation or by returning an error status. For more information, see Remarks.

Return value

None

Remarks

SpbCx manages the I/O queue for the SPB controller. SpbCx calls this function when a client (peripheral driver) of the controller sends an IOCTL_SPB_UNLOCK_CONTROLLER request to a target on the bus. The UnlockRequest parameter value is a handle that encapsulates this request.

The EvtSpbControllerLock and EvtSpbControllerUnlock functions perform complementary operations. Both functions are optional. If your SPB controller driver implements an EvtSpbControllerUnlock function, the driver is not required to implement an EvtSpbControllerLock function, but might do so. However, if your SPB controller driver implements an EvtSpbControllerLock function, it must also implement an EvtSpbControllerUnlock function. For more information, see Remarks in SPB_CONTROLLER_CONFIG.

If the SPB controller driver needs to change the mode of its controller to restore normal target selection, it can do so during the EvtSpbControllerUnlock callback. If this change of mode involves a long delay or requires the driver to wait for a device interrupt, the driver should initiate the mode change and then return from the callback without delay. Later, the driver can complete the unlock request in an interrupt DPC or a timer DPC.

An EvtSpbControllerUnlock callback must avoid failing an unlock request. If Driver Verifier is enabled, such a failure will trigger a verifier trap, which will report to the Plug and Play manager that the controller has failed. SpbCx ignores the failure of an unlock request and does not try to handle or mitigate the failure.

The EvtSpbControllerUnlock function does not return a value. Instead, the SPB controller driver indicates the status of the unlock operation in the completion status of the I/O request that is identified by the UnlockRequest parameter. Set the completion status to STATUS_SUCCESS.

To register an EvtSpbControllerUnlock callback function, call the SpbDeviceInitialize method.

For more information about the EvtSpbControllerUnlock function, see Handling Client-Implemented Sequences.

Examples

To define an EvtSpbControllerUnlock callback function, you must first provide a function declaration that identifies the type of callback function you're defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it's a requirement for writing drivers for the Windows operating system.

For example, to define an EvtSpbControllerUnlock callback function that is named MyEvtSpbControllerUnlock, use the EVT_SPB_CONTROLLER_UNLOCK function type, as shown in this code example:

EVT_SPB_CONTROLLER_UNLOCK  MyEvtSpbControllerUnlock;

Then, implement your callback function as follows:

_Use_decl_annotations_
VOID
  MyEvtSpbControllerUnlock(
    WDFDEVICE Controller,
    SPBTARGET Target,
    SPBREQUEST UnlockRequest
    )
{ ... }

The EVT_SPB_CONTROLLER_UNLOCK function type is defined in the Spbcx.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the Use_decl_annotations annotation to your function definition. The Use_decl_annotations annotation ensures that the annotations that are applied to the EVT_SPB_CONTROLLER_UNLOCK function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for KMDF Drivers. For more information about Use_decl_annotations, see Annotating Function Behavior.

Requirements

Requirement	Value
Minimum supported client	Supported starting with Windows 8.
Target Platform	Desktop
Header	spbcx.h
IRQL	Called at IRQL <= DISPATCH_LEVEL.

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