[edk2-devel] [PATCH edk2-platforms v3 16/24] Silicon/NXP: Add Chassis2 Package

[Pankaj Bansal]

> -----Original Message-----
> From: Leif Lindholm <leif at nuviainc.com>
> Sent: Thursday, April 23, 2020 5:27 PM
> To: Pankaj Bansal (OSS) <pankaj.bansal at oss.nxp.com>
> Cc: Meenakshi Aggarwal <meenakshi.aggarwal at nxp.com>; Michael D Kinney
> <michael.d.kinney at intel.com>; devel at edk2.groups.io; Varun Sethi
> <V.Sethi at nxp.com>; Samer El-Haj-Mahmoud <Samer.El-Haj-
> Mahmoud at arm.com>; Jon Nettleton <jon at solid-run.com>; Ard Biesheuvel
> <ard.biesheuvel at linaro.org>
> Subject: Re: [PATCH edk2-platforms v3 16/24] Silicon/NXP: Add Chassis2
> Package
> 
> 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.

You mean put ChassisLibConstructor() call in SerialPortInitialize () ?

> 
> /
>     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
> > >
> >

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