On Thu, Apr 23, 2020 at 11:38:12 +0000, Pankaj Bansal (OSS) wrote:
> > > +
> > > + @return The value read.
> > > +**/
> > > +UINT32
> > > +EFIAPI
> > > +DcfgRead32 (
> > > + IN UINTN Address
> > > + )
> > > +{
> > > + MMIO_OPERATIONS_32 *DcfgOps;
> > > +
> > > + DcfgOps = GetMmioOperations32 (FeaturePcdGet (PcdDcfgBigEndian));
> > > +
> > > + return DcfgOps->Read32 (Address);
> > > +}
> >
> > The intended usage model for IoAccessLib is to retrieve the function
> > pointer struct once and then always refer to it. Since this is a
> > library, we could have a CONSTRUCTOR function (specified in the .inf)
>
> I had thought of this, but decided against it because of this reason:
> The order of Library constructor call for a module cannot be guaranteed.
> https://edk2.groups.io/g/devel/message/57254 is an good example of this.
> BaseDebugLibSerialPortConstructor would need to depend on
> ChassisLibConstructor,
> to retrieve the UART clock frequency. If the constructor calls are not
> guaranteed, BaseDebugLibSerialPortConstructor
> would fail and it would cause ASSERT due to ASSERT_RETURN_ERROR (Status)
If this is a problem (and I recall Ard pointing out some shortcomings
in the dependency handling in the past), we can solve this with an
explicit initialisation call in the SoC or platform init code.
/
Leif
>
> > and do something like:
> >
> > STATIC MMIO_OPERATIONS mDcfgOps;
> >
> > /**
> > Read Dcfg register
> >
> > @param Address The MMIO register to read.
> >
> > @return The value read.
> > **/
> > UINT32
> > EFIAPI
> > DcfgRead32 (
> > IN UINTN Address
> > )
> > {
> > return mDcfgOps->Read32 (Address);
> > }
> >
> > /**
> > Write Dcfg register
> >
> > @param Address The MMIO register to write.
> > @param Value The value to write to the MMIO register.
> >
> > @return Value.
> >
> > **/
> > UINT32
> > EFIAPI
> > DcfgWrite32 (
> > IN UINTN Address,
> > IN UINT32 Value
> > )
> > {
> > return mDcfgOps->Write32 (Address, Value);
> > }
> >
> > ...
> >
> > /**
> > The constructor function initializes the IoAccessLib
> > function pointer structure.
> >
> > @retval RETURN_SUCCESS The constructor always returns EFI_SUCCESS.
> >
> > **/
> > EFI_STATUS
> > EFIAPI
> > ChassisLibConstructor (
> > VOID
> > )
> > {
> > mDcfgOps = GetMmioOperations (FeaturePcdGet (PcdDcfgBigEndian));
> >
> > return EFI_SUCCESS;
> > }
> >
> > /
> > Leif
> >
>
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#57962): https://edk2.groups.io/g/devel/message/57962
Mute This Topic: https://groups.io/mt/73008827/21656
Group Owner: [email protected]
Unsubscribe: https://edk2.groups.io/g/devel/unsub [[email protected]]
-=-=-=-=-=-=-=-=-=-=-=-
