Describes the interrupt functions involved in implementing the GPIO interface class.
A common use for a pin is as a hardware interrupt source. The treatment of interrupts is platform dependent. Typically, the hardware multiplexes all interrupts from a module into a hardware controller: in this case it is part of the GPIO implementation to demultiplex the requests. A GPIO implementation with the capability to demultiplex will also have the capability to enable and disable interrupts and to bind and unbind their handlers.
Implement BindInterrupt() with
return value KErrNone.
Associate the specified interrupt service routine with the specified pin ID.
Implement BindInterrupt() with
return value KErrInUse.
Return KErrInUse if an interrupt service
routine is already bound to this interrupt.
Implement UnbindInterrupt() with
return value KErrNone.
Unbind the specified interrupt service routine with the specified pin ID.
Implement EnableInterrupt() with
return value KErrNone.
Verify that the pin is being used as an interrupt source and that there is an ISR bound to it. Enable the interrupt.
Implement DisableInterrupt() with
return value KErrNone.
Verify that the pin is being used as an interrupt source and that there is an ISR bound to it. Disable the interrupt.
Implement IsInterruptEnabled() with return value KErrNone.
Verify that the pin is being used as an interrupt source
and that there is an ISR bound to it. Determine the status
of the interrupt. If it is enabled set aEnable to True and if it is disabled set aEnable to False.
Implement ClearInterrupt() with
return value KErrNone.
Clear the interrupt.
Only implement this if the hardware does not automatically clear the interrupt after reading the interrupt status.
Implement GetMaskedInterruptState() with return value KErrNone.
Read the interrupt state from the GPIO interrupt controller, probably by using a bit mask on a register. Set aActive to True if the interrupt state is active and to False if it is inactive.
Implement GetRawInterruptState() with return value KErrNone.
Read the interrupt state directly from the pin. Set
aActive to True if the interrupt state is
active and to False if it is inactive.
If the hardware does not allow the raw interrupt state to
be read, implement the function to return KErrNotSupported or to return the same value as GetMaskedInterruptState().
Implement these functions with return value
KErrNotSupported:
BindInterrupt()
UnbindInterrupt()
EnableInterrupt()
DisableInterrupt()
IsInterruptEnabled()
Return KErrNotSupported for
these functions if the pin does not support interrupts.
Implement these functions with return value
KErrGeneral:
UnbindInterrupt()
EnableInterrupt()
DisableInterrupt()
IsInterruptEnabled()
Return KErrGeneral for these
functions if there is no Interrupt Service Routine bound
to the pin.
Implement ClearInterrupt() with
return value KErrNotSupported.
Return KErrNotSupported if the
pin does not support clearing the interrupt signal.
Implement GetMaskedInterruptState() with return value KErrNotSupported.
Return KErrNotSupported if reading the interrupt state is not supported.
Implement GetRawInterruptState() with return value KErrNotSupported.
Return KErrNotSupported if reading raw interrupt states is not supported.