Binding +and Unbinding

To handle events, the interrupt source and the ISR have to be registered +with the OS: this is called binding the interrupt. An interrupt +has to be unbound when its use is complete.

Binding

An +interrupt source ID is bound with the driver's interrupt service routine. +This is done using the function Interrupt::Bind() in the second +stage constructor of the physical channel. Interrupt binding can fail +if the source has been already used or bound.

TInt DExUartPhysicalChannelH4::DoCreate(TInt aUnit, const TDesC8* aInfo, const TVersion& aVer) + { + ... + // Bind the interrupt service routine (ISR) to a specific + // interrupt ID. When the ISR is called, the value aPtr, + // (here this object) is passed as the argument. The ISR + // must be a static void function, taking a single TAny* + // parameter: void Isr(TAny* aParam). Interrupt::Enable() + // must be called to start receiving interrupts. Bind() + // returns KErrInUse if the ISR is already bound. + // + TInt r = Interrupt::Bind(iIrqId,UartIsr,this); + if (r!=KErrNone) + { + KDBG(Kern::Printf("DExUartPhysicalChannel::Interrupt Binding + for UART failed")); + return r; + } + + return KErrNone; + }

Unbinding

An +interrupt is unbound by calling Interrupt::UnBind(), which +de-registers the interrupt source and routine. This must be done before or +during physical channel destruction. Unbinding an interrupt does not disable +its source. Interrupts have to be disabled explicitly before unbinding to +avoid spurious interrupts.

/** + Physical channel destructor. Delete and free any objects created and + allocated by the physical channel. This is called by the + framework while unloading the driver (PDD). + */ +DExUartPhysicalChannelH4::~DExUartPhysicalChannelH4() + { + // Unbind the UART interrupt. Interrupt::Unbind() frees the + // interrupt service routine (ISR) function from the specified + // interrupt ID. + // + Interrupt::Unbind (iIrqId); + }