2.18. InterruptEnable()


	Chapter 2. WD_xxx PCI/PCMCIA/ISA Functions

Purpose

A convenient function for setting up interrupt handling.

Prototype

DWORD InterruptEnable(
    HANDLE *phThread,
    HANDLE hWD,
    WD_INTERRUPT *pInt,
    INT_HANDLER func,
    PVOID pData);

Parameters

Name	Type	Input/Output
phThread	HANDLE*	Output
hWD	HANDLE	Input
pInt	WD_INTERRUPT*
• hInterrupt	DWORD	Input
• dwOptions	DWORD	Input
• Cmd	WD_TRANSFER*	Input
• dwCmds	DWORD	Input
• kpCall	WD_KERNEL_PLUGIN_CALL
* hKernelPlugIn	DWORD	Input
* dwMessage	DWORD	N/A
* pData	PVOID	N/A
* dwResult	DWORD	N/A
• fEnableOk	DWORD	N/A
• dwCounter	DWORD	N/A
• dwLost	DWORD	N/A
• fStopped	DWORD	N/A
• dwLastMessage	DWORD	N/A
• dwEnabledIntType	DWORD	Output
func	typedef void (*INT_HANDLER)(PVOID pData);	Input
pData	PVOID	Input

Description

Name	Description
phThread	Pointer to the handle to the spawned interrupt thread, which should be passed to `InterruptDisable`() [2.19] when disabling the interrupt
hWD	Handle to WinDriver's kernel-mode driver as received from `WD_Open`() [5.2]
pInt	Pointer to an interrupt information structure:
• hInterrupt	Internal interrupt handle, as received from `WD_CardRegister`() [2.8] in `I.Int.hInterrupt`
• dwOptions	A bit mask of interrupt handling flags — can be set to zero for no options, or to a combination of any of the following flags: `INTERRUPT_CMD_COPY`: If set, WinDriver will copy any data read in the kernel as a result of a read transfer command, and return it to the user within the relevant transfer command structure. The user will be able to access the data from his user-mode interrupt handler routine (`func`). The following flags are applicable only to PCI interrupts on Linux. If set, these flags determine the types of interrupts that may be enabled for the device — the function will attempt to enable only interrupts of the specified types, using the following precedence order, provided the type is reported as supported by the device: `INTERRUPT_MESSAGE_X`: Extended Message-Signaled Interrupts (MSI-X) `INTERRUPT_MESSAGE`: Message-Signaled Interrupts (MSI) `INTERRUPT_LEVEL_SENSITIVE` — Legacy level-sensitive interrupts
• Cmd	An array of transfer commands information structures that define the operations to be performed at the kernel level upon the detection of an interrupt, or `NULL` if no transfer commands are required. NOTE: • Memory allocated for the transfer commands must remain available until the interrupts are disabled . • When handling level-sensitive interrupts (such as PCI interrupts) in the user mode (without a Kernel PlugIn driver), you must use this array to define the hardware-specific commands for acknowledging the interrupts in the kernel, immediately when they are received. The commands in the array can be either of the following: • A read/write transfer command that conforms to the following format: `<dir><p>_[S]<size>` — see the description of `pTrans->cmdTrans` in Section 2.11. • `CMD_MASK`: an interrupt mask command for determining the source of the interrupt: When this command is set, upon the arrival of an interrupt in the kernel WinDriver masks the value of the previous read command in the `WD_TRANSFER` commands array with the mask that is set in the relevant `Data` field union member of the mask transfer command. For example, for a `Cmd` `WD_TRANSFER` array, if `Cmd[i-1].cmdTrans` is `RM_BYTE`, WinDriver performs the following mask: `Cmd[i-1].Data.Byte & Cmd[i].Data.Byte`. If the mask is successful, the driver claims ownership of the interrupt and when the control is returned to the user mode, the interrupt handler routine that was passed to the interrupt enable function is invoked; otherwise, the driver rejects ownership of the interrupt, the interrupt handler routine is not invoked and the subsequent transfer commands in the array are not executed. (Acceptance and rejection of the interrupt is relevant only when handling legacy interrupts; since MSI/MSI-X interrupts are not shared, WinDriver will always accept control of such interrupts.) NOTE: A `CMD_MASK` command must be preceded by a read transfer command (`RM_XXX` / `RP_XXX`).
• dwCmds	Number of transfer commands in the `Cmd` array
• kpCall	Kernel PlugIn message information structure:
* hKernelPlugIn	Handle to Kernel PlugIn returned from `WD_KernelPlugInOpen`() [6.1].
• dwEnabledIntType	Updated by the function to indicate the type of interrupt enabled for the device. Can be set to any of the following values: • `INTERRUPT_MESSAGE_X`: Extended Message-Signaled Interrupts (MSI-X). ^* • `INTERRUPT_MESSAGE`: Message-Signaled Interrupts (MSI). ^* • `INTERRUPT_LEVEL_SENSITIVE`: Legacy level-sensitive interrupts. • `0`: Default interrupt type — Legacy edge-triggered interrupts. NOTE: ^* The Windows APIs do not distinguish between MSI and MSI-X; therefore, on this OS the WinDriver functions set the `INTERRUPT_MESSAGE` flag for both MSI and MSI-X. ^** This field normally relevant only in the case of PCI devices that support more than one type of interrupt.
func	The interrupt handler routine, which will be called once for every interrupt occurrence. (Note: The `INT_HANDLER` function type is defined in windrvr_int_thread.h).
pData	Pointer to the data to be passed as the argument to the interrupt handler routine (`func`)

Return Value

Returns WD_STATUS_SUCCESS (0) on success, or an appropriate error code otherwise [A].

Remarks

You can view the implementation of this function in WinDriver/src/wdapi/windrvr_int_thread.c.
InterruptEnable() uses the low-level WD_IntEnable() [3.2], WD_IntWait() [3.3] and WD_IntCount() [3.4] functions and replaces the need to call these functions separately, although this is still possible.
WinDriver must be registered with the OS as the driver of the device before enabling interrupts. For Plug-and-Play hardware (PCI/PCI Express/PCMCIA) on Windows platforms, this association is made by installing an INF file for the device. If the INF file is not installed, InterruptEnable() will fail with a WD_NO_DEVICE_OBJECT error [A]. To improve the interrupt handling rate on Windows and Linux, consider using WinDriver's Kernel PlugIn feature (see the WinDriver PCI Manual).

Example

VOID DLLCALLCONV interrupt_handler(PVOID pData)
{
    WD_INTERRUPT *pIntrp = (WD_INTERRUPT *)pData;
    /* Implement your interrupt handler routine here */

    printf("Got interrupt %d\n", pIntrp->dwCounter);
}

....
main()
{
    WD_CARD_REGISTER cardReg;
    WD_INTERRUPT Intrp;
    HANDLE hWD, thread_handle;

    ....
    hWD = WD_Open();
    BZERO(cardReg);
    cardReg.Card.dwItems = 1;
    cardReg.Card.Item[0].item = ITEM_INTERRUPT;
    cardReg.Card.Item[0].fNotSharable = 1;
    cardReg.Card.Item[0].I.Int.dwInterrupt = MY_IRQ;
    cardReg.Card.Item[0].I.Int.dwOptions = 0;
    ....
    WD_CardRegister(hWd, &cardReg);
    ....
    PVOID pdata = NULL;
    BZERO (Intrp);
    Intrp.hInterrupt = cardReg.Card.Item[0].I.Int.hInterrupt;
    Intrp.Cmd = NULL;
    Intrp.dwCmds = 0;
    Intrp.dwOptions = 0;
    printf("starting interrupt thread\n");
    pData = &Intrp;

    if (InterruptEnable(&thread_handle, hWD, &Intrp,
        interrupt_handler, pdata))
    {
        printf ("failed enabling interrupt\n")
    }
    else
    {
        printf("Press Enter to uninstall interrupt\n");
        fgets(line, sizeof(line), stdin);
        InterruptDisable(thread_handle); /* Calls WD_IntDisable() */
    }
    WD_CardUnregister(hWD, &cardReg);
    ....
}


2.17. WD_PcmciaControl()		2.19. InterruptDisable()