Leif, I agree that this should be described as byte swapping.
What about a module that needs to access HW with and without the bytes swapped? It gets more complex if a module is linked against several libs and some libs access HW with bytes swapped and some do not. Thanks, Mike > -----Original Message----- > From: edk2-devel [mailto:edk2-devel- > [email protected]] On Behalf Of Leif Lindholm > Sent: Wednesday, November 29, 2017 4:51 AM > To: Meenakshi Aggarwal <[email protected]>; > Gao, Liming <[email protected]> > Cc: Kinney, Michael D <[email protected]>; > [email protected]; Ard Biesheuvel > <[email protected]> > Subject: Re: [edk2] [PATCH 1/1] MdePkg/IoLib: Add > support for big-endian MMIO > > Hi Meenakshi, > > I finally got around to looking at the watchdog code > (that uses this > library), and that has convinced me the best solution > is to do what > Liming proposed. > > Looking at this snippet: > > > +STATIC > > +UINT16 > > +EFIAPI > > +WdogRead ( > > + IN UINTN Address > > + ) > > +{ > > + if (FixedPcdGetBool (PcdWdogBigEndian)) { > > + return BeMmioRead16 (Address); > > + } else { > > + return MmioRead16(Address); > > + } > > This is actually a pretty good demonstration of the > arguments that > were made with regards to how the BeIoLib could be just > another > implementation of IoLib. > > You would then just do (in your .dsc): > Platform/NXP/Drivers/WatchDog/WatchDogDxe.inf { > IoLib|<path to BeIoLib .inf> > } > > This causes the big-endian version of the library to be > used for this > component. This makes these Wdog<access> functions and > the Pcd > redundant, and the rest of the code can use > MmioRead16()/MmioWrite16() > directly. > > But then, it is not really a big-endian or litte-endian > version of the > library we need. We always know which endianness we are > building for. > What we need is a byteswapping flavour of IoLib. > > So Liming, what if we do something like adding a > MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicSwa > p.inf > --- > [Defines] > INF_VERSION = 0x0001001A > BASE_NAME = > BaseIoLibIntrinsicSwap > MODULE_UNI_FILE = > BaseIoLibIntrinsic.uni > FILE_GUID = d4a60d44-3688-4a50- > b2d0-5c6fc2422523 > MODULE_TYPE = BASE > VERSION_STRING = 1.0 > LIBRARY_CLASS = IoLib > > > # > # VALID_ARCHITECTURES = IA32 X64 EBC IPF ARM > AARCH64 > # > > [Sources] > BaseIoLibIntrinsicInternal.h > IoHighLevel.c > IoLib.c > IoLibEbc.c # Asserts on all i/o port accesses > IoLibMmioBuffer.c > > [Packages] > MdePkg/MdePkg.dec > > [LibraryClasses] > DebugLib > BaseLib > > [BuildOptions] > GCC:*_*_*_CC_FLAGS = -DSWAP_BYTES > --- > > And then add > > #ifdef SWAP_BYTES > return SwapBytesXX (Value); > #else > return Value; > #fi > > for the read operations and > > #ifdef SWAP_BYTES > *(type)Address = SwapBytesXX (Value); > #else > *(type)Address = Value; > #fi > > for the write operations in IoLib.c? > > / > Leif > > On Mon, Nov 27, 2017 at 06:06:33AM +0000, Meenakshi > Aggarwal wrote: > > Hi Leif, > > > > This is regarding Big-Endian Library patch ([PATCH v2 > 1/9] > > Platform/NXP: Add support for Big Endian Mmio APIs) > > > > We have started this discussion before and the > suggestion was to > > create a separate .inf file keeping APIs name same > > e.g. MmioRead/MmioWrite in MdePkg. > > > > But we can't go with this approach (reason mentioned > by Udit). > > > > So please suggest if we should keep this library > under Platform/NXP > > or I send a new patch moving this library in MdePkg. > > > > But we have to keep a different name for Big Endian > MMIO APIs. > > > > > > Thanks, > > Meenakshi > > > > > > > -----Original Message----- > > > From: Udit Kumar > > > Sent: Monday, October 23, 2017 12:38 PM > > > To: Gao, Liming <[email protected]>; Meenakshi > Aggarwal > > > <[email protected]>; Ard Biesheuvel > > > <[email protected]>; Kinney, Michael D > > > <[email protected]>; edk2- > [email protected] > > > Subject: RE: [edk2] [PATCH 1/1] MdePkg/IoLib: Add > support for big-endian > > > MMIO > > > > > > Hi Meenakshi/Liming, > > > My 2 cents, around this. > > > > > > 1) > > > Having a new lib for BE read might not be helpful > for us, e.g. a IP which is in > > > BE mode access the UART for print or system > registers which are in LE, then > > > with new Lib, we will get all read/write in BE mode > > > > > > 2) > > > Especially for our IPs, which are changing from BE > to LE depending on > > > platform. > > > As said before, having BE read lib with API name of > MmioRead32 etc, will not > > > help (I guess Meenakshi already seen some problems > around this) Adding a > > > new lib with MmioRead32BE API name could help, but > IP driver we need to > > > take care of IP mode either by Pcd or #define, to > select MmioRead32 or > > > MmioRead32BE. > > > This conditional compile needs to be done for all > IPs (which works in BE/LE > > > mode on different platforms). > > > > > > My preferred way of implementation to use one > function in IP driver, And > > > based on IP mode, do the switch. > > > > > > New Lib could have function like below > > > MmioRead32Generic(IN UINTN Address, BOOL > IsIPBE) { > > > UINT32 Value; > > > > > > ASSERT ((Address & 3) == 0); > > > Value = *(volatile UINT32*)Address; > > > If(IsIPBE) > > > Value = SwapBytes32(Value); > > > return Value; > > > } > > > > > > And IP driver can use it > > > MmioRead32Generic(ADDR, > > > FixedPcdGet(This_IP_Mode_For_This_platform) > > > > > > Comments are welcome. > > > > > > Regards > > > Udit > > > > > > > -----Original Message----- > > > > From: edk2-devel [mailto:edk2-devel- > [email protected]] On Behalf Of > > > > Gao, Liming > > > > Sent: Monday, October 16, 2017 8:48 AM > > > > To: Meenakshi Aggarwal > <[email protected]>; Ard Biesheuvel > > > > <[email protected]>; Kinney, Michael D > > > > <[email protected]>; edk2- > [email protected] > > > > Subject: Re: [edk2] [PATCH 1/1] MdePkg/IoLib: Add > support for > > > > big-endian MMIO > > > > > > > > Meenakshi: > > > > I suggest to introduce new IoLib library > instance, not to add new IoLib > > > APIs. > > > > New IoLib library instance will perform IO > operation as the big > > > > endian. You can update > MdePkg/Library/BaseIoLibIntrinsic instance, add > > > > new source file and new INF for it. > > > > > > > > UINT32 > > > > EFIAPI > > > > MmioRead32 ( > > > > IN UINTN Address > > > > ) > > > > { > > > > UINT32 Value; > > > > > > > > ASSERT ((Address & 3) == 0); > > > > Value = *(volatile UINT32*)Address; > > > > return SwapBytes32(Value); > > > > } > > > > > > > > Thanks > > > > Liming > > > > >-----Original Message----- > > > > >From: Meenakshi Aggarwal > [mailto:[email protected]] > > > > >Sent: Friday, October 13, 2017 2:07 PM > > > > >To: Ard Biesheuvel <[email protected]>; > Kinney, Michael D > > > > ><[email protected]>; edk2- > [email protected]; Gao, Liming > > > > ><[email protected]> > > > > >Subject: RE: [edk2] [PATCH 1/1] MdePkg/IoLib: > Add support for > > > > >big-endian MMIO > > > > > > > > > >Hi All, > > > > > > > > > > > > > > >It’s a pretty old discussion, we have left the > upstreaming of NXP > > > > >package in between because of some other work, > but have started it > > > > >again > > > > now. > > > > > > > > > > > > > > >Issue : Few NXP modules support Big Endian > MMIOs as these are ported > > > > >from PowerPC. > > > > > > > > > >Solution suggested : Create a separate library > for BE MMIO APIs. > > > > > > > > > > > > > > >So what I have done is, I have created a > separate library to support > > > > >BE MMIO APIs and currently keeping it to my > package. > > > > >This library is basically a wrapper over > existing MMIO APIs. > > > > > > > > > >UINT32 > > > > >EFIAPI > > > > >BeMmioRead32 ( > > > > > IN UINTN Address > > > > > ) > > > > >{ > > > > > UINT32 Value; > > > > > > > > > > Value = MmioRead32(Address); > > > > > > > > > > return SwapBytes32(Value); > > > > >} > > > > > > > > > > > > > > >Need your opinion on below optinos: > > > > > > > > > >1. Will this be a good idea to make this library > a part of MdePkg? OR > > > > > > > > > >2. Add a new file e.g. IoBeMmio.c like > IoHighLevel.c in > > > > >MdePkg/Library/BaseIoLibIntrinsic/ > > > > > And made these APIs a part of IoLib itself. OR > > > > > > > > > >3. Keep this library internal to NXP package. > > > > > > > > > > > > > > >Please provide your inputs. > > > > > > > > > > > > > > >Thanks & Regards, > > > > >Meenakshi > > > > > > > > > >> -----Original Message----- > > > > >> From: Bhupesh Sharma > > > > >> Sent: Monday, October 17, 2016 3:28 PM > > > > >> To: Ard Biesheuvel > <[email protected]>; Kinney, Michael D > > > > >> <[email protected]> > > > > >> Cc: Gao, Liming <[email protected]>; edk2- > [email protected]; > > > > >> Meenakshi Aggarwal > <[email protected]> > > > > >> Subject: RE: [edk2] [PATCH 1/1] MdePkg/IoLib: > Add support for > > > > >> big-endian MMIO > > > > >> > > > > >> Hi Ard, > > > > >> > > > > >> > -----Original Message----- > > > > >> > From: Ard Biesheuvel > [mailto:[email protected]] > > > > >> > Sent: Monday, October 17, 2016 1:12 PM > > > > >> > To: Kinney, Michael D > <[email protected]> > > > > >> > Cc: Gao, Liming <[email protected]>; > Bhupesh Sharma > > > > >> > <[email protected]>; edk2- > [email protected] > > > > >> > Subject: Re: [edk2] [PATCH 1/1] > MdePkg/IoLib: Add support for > > > > >> > big- endian MMIO > > > > >> > > > > > >> > On 17 October 2016 at 05:10, Kinney, Michael > D > > > > >> > <[email protected]> wrote: > > > > >> > > Bhupesh, > > > > >> > > > > > > >> > > It is also possible to add an ARM specific > PCD to select > > > > >> > > endianness and update > > > > >> > > > MdePkg/Library/BaseIoLibIntrinsic/IoLibArm.c to use > that PCD in > > > > >> > > MmioRead/Write() APIs in that file to > support both endian types. > > > > >> > > You can use the SwapBytesxx() functions > from BaseLib(as > > > > >> > Laszlo > > > > >> > > suggested) based on the setting of this > ARM specific PCD. > > > > >> > > > > > > >> > > Modules that link against this lib can > select endianness by > > > > >> > > setting PCD in the scope of that module. > > > > >> > > > > > > >> > > The IPF version of IoLib uses an IPF > specific PCD to translate > > > > >> > > I/O port accesses to MMIO accesses. So > there is already an > > > > >> > > example of an arch specific PCD in this > lib instance. > > > > >> > > > > > > >> > > > > > >> > This is not a platform wide thing, it is a > per-device property > > > > >> > whether the MMIO occurs in big endian or > little endian manner. > > > > >> > > > > > >> > So I think Liming's suggestion makes sense: > create an IoLib > > > > >> > implementation that performs the byte > swapping, and selectively > > > > >> > incorporate it into drivers that require it > using > > > > >> > > > > > >> > BeMmioDeviceDxe.inf { > > > > >> > <LibraryClasses> > > > > >> > IoLib|SomePkg/Library/BigEndianIoLib.inf > > > > >> > } > > > > >> > > > > >> That's correct. I think creating a separate > IoLib for byte-swapping > > > > >> makes sense. > > > > >> > > > > >> We will rework the patch accordingly. > > > > >> > > > > >> Regards, > > > > >> Bhupesh > > > > _______________________________________________ > > > > edk2-devel mailing list > > > > [email protected] > > > > https://lists.01.org/mailman/listinfo/edk2-devel > _______________________________________________ > edk2-devel mailing list > [email protected] > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
