Re: [PATCH v6 2/3] MdePkg: add SBI-based SerialPortLib for RISC-V

["Andrei Warkentin" <andrei.warkentin@intel.com>]

Thanks Sunil, I have in fact missed your email.

Will apply your feedback, retest and resend.

A

> -----Original Message-----
> From: Sunil V L <sunilvl@ventanamicro.com>
> Sent: Thursday, April 6, 2023 12:00 AM
> To: Warkentin, Andrei <andrei.warkentin@intel.com>
> Cc: devel@edk2.groups.io; Daniel Schaefer <git@danielschaefer.me>;
> Kinney, Michael D <michael.d.kinney@intel.com>; Gao, Liming
> <gaoliming@byosoft.com.cn>; Liu, Zhiguang <zhiguang.liu@intel.com>; Gerd
> Hoffmann <kraxel@redhat.com>
> Subject: Re: [PATCH v6 2/3] MdePkg: add SBI-based SerialPortLib for RISC-V
> 
> Hi Andrei,
> 
> I had couple of questions on previous version of this patch. Adding them
> inline again in case you had missed them. Please check if they are valid.
> 
> Also, I think it would be better to have single directory
> BaseSerialPortLibRiscVSbiLib and inside that we can have both INF files.
> This way we can share UNI files etc between both libraries.
> 
> On Tue, Apr 04, 2023 at 11:43:58AM -0500, Andrei Warkentin wrote:
> > These are implementations of SerialPortLib using SBI console services.
> > - BaseSerialPortLibRiscVSbiLib is appropriate for SEC/PEI (XIP)
> > environments
> > - BaseSerialPortLibRiscVSbiLibRam is appropriate for PrePI/DXE
> > environments
> >
> > Tested with:
> > - Qemu RiscVVirt (non-DBCN case, backed by UART)
> > - TinyEMU + RiscVVirt (non-DBCN case, HTIF)
> > - TinyEMU + RiscVVirt (DBCN case, HTIF)
> >
> > Cc: Daniel Schaefer <git@danielschaefer.me>
> > Cc: Sunil V L <sunilvl@ventanamicro.com>
> > Cc: Michael D Kinney <michael.d.kinney@intel.com>
> > Cc: Liming Gao <gaoliming@byosoft.com.cn>
> > Cc: Zhiguang Liu <zhiguang.liu@intel.com>
> > Acked-by: Gerd Hoffmann <kraxel@redhat.com>
> > Signed-off-by: Andrei Warkentin <andrei.warkentin@intel.com>
> > ---
> >  MdePkg/MdePkg.dsc                                                                  |   2 +
> >
> MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRiscVSbiLib.in
> f       |  39 +++
> >
> MdePkg/Library/BaseSerialPortLibRiscVSbiLibRam/BaseSerialPortLibRiscVSbiL
> ibRam.inf |  36 +++
> >
> MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRiscVSbiLib.c
> | 233 ++++++++++++++++
> >
> MdePkg/Library/BaseSerialPortLibRiscVSbiLibRam/BaseSerialPortLibRiscVSbiL
> ibRam.c   | 288 ++++++++++++++++++++
> >
> MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRiscVSbiLib.u
> ni       |  16 ++
> >
> > MdePkg/Library/BaseSerialPortLibRiscVSbiLibRam/BaseSerialPortLibRiscVS
> > biLibRam.uni |  16 ++
> >  7 files changed, 630 insertions(+)
> >
> > diff --git a/MdePkg/MdePkg.dsc b/MdePkg/MdePkg.dsc index
> > 0ac7618b4623..ceccc078ff04 100644
> > --- a/MdePkg/MdePkg.dsc
> > +++ b/MdePkg/MdePkg.dsc
> > @@ -192,5 +192,7 @@ [Components.ARM, Components.AARCH64]
> >
> >  [Components.RISCV64]
> >    MdePkg/Library/BaseRiscVSbiLib/BaseRiscVSbiLib.inf
> > +
> > + MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRiscVSb
> > + iLib.inf
> > + MdePkg/Library/BaseSerialPortLibRiscVSbiLibRam/BaseSerialPortLibRisc
> > + VSbiLibRam.inf
> >
> >  [BuildOptions]
> > diff --git
> > a/MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRiscVSb
> > iLib.inf
> > b/MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRiscVSb
> > iLib.inf
> > new file mode 100644
> > index 000000000000..09cf59f190f6
> > --- /dev/null
> > +++ b/MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRis
> > +++ cVSbiLib.inf
> > @@ -0,0 +1,39 @@
> > +## @file
> > +#  Serial Port Library backed by SBI console.
> > +#
> > +#  Meant for SEC and PEI (XIP) environments.
> > +#
> > +#  Due to limitations of SBI console interface and XIP environments #
> > +(on use of globals), this library instance does not implement reading
> > +#  and polling the serial port. See PrePiDxeSerialPortLibRiscVSbi for
> > +#  the full-featured variant meant for PrePi and DXE environments.
> > +#
> > +#  Copyright (c) 2023, Intel Corporation. All rights reserved.<BR> #
> > +#  SPDX-License-Identifier: BSD-2-Clause-Patent # # ##
> > +
> > +[Defines]
> > +  INF_VERSION                    = 0x0001001B
> > +  BASE_NAME                      = BaseSerialPortLibRiscVSbiLib
> > +  MODULE_UNI_FILE                = BaseSerialPortLibRiscVSbiLib.uni
> > +  FILE_GUID                      = 639fad38-4bfd-4eb9-9f09-e97c7947d480
> > +  MODULE_TYPE                    = BASE
> > +  VERSION_STRING                 = 1.0
> > +  LIBRARY_CLASS                  = SerialPortLib | SEC PEI_CORE PEIM
> > +
> > +
> > +#
> > +#  VALID_ARCHITECTURES           = RISCV64
> > +#
> > +
> > +[Sources]
> > +  BaseSerialPortLibRiscVSbiLib.c
> > +
> > +[Packages]
> > +  MdePkg/MdePkg.dec
> > +
> > +[LibraryClasses]
> > +  RiscVSbiLib
> > diff --git
> > a/MdePkg/Library/BaseSerialPortLibRiscVSbiLibRam/BaseSerialPortLibRisc
> > VSbiLibRam.inf
> > b/MdePkg/Library/BaseSerialPortLibRiscVSbiLibRam/BaseSerialPortLibRisc
> > VSbiLibRam.inf
> > new file mode 100644
> > index 000000000000..b7ad1548a309
> > --- /dev/null
> > +++ b/MdePkg/Library/BaseSerialPortLibRiscVSbiLibRam/BaseSerialPortLib
> > +++ RiscVSbiLibRam.inf
> > @@ -0,0 +1,36 @@
> > +## @file
> > +#  Serial Port Library backed by SBI console.
> > +#
> > +#  Meant for PrePi and DXE environments (where globals are allowed).
> > +See #  BaseSerialPortLibRiscVSbiLib for a reduced variant appropriate
> > +for SEC #  and PEI (XIP) environments.
> > +#
> > +#  Copyright (c) 2023, Intel Corporation. All rights reserved.<BR> #
> > +#  SPDX-License-Identifier: BSD-2-Clause-Patent # # ##
> > +
> > +[Defines]
> > +  INF_VERSION                    = 0x0001001B
> > +  BASE_NAME                      = BaseSerialPortLibRiscVSbiLibRam
> > +  MODULE_UNI_FILE                = BaseSerialPortLibRiscVSbiLibRam.uni
> > +  FILE_GUID                      = 872af743-ab56-45b4-a065-602567f4820c
> > +  MODULE_TYPE                    = BASE
> > +  VERSION_STRING                 = 1.0
> > +  LIBRARY_CLASS                  = SerialPortLib | SEC DXE_CORE DXE_DRIVER
> DXE_RUNTIME_DRIVER UEFI_DRIVER UEFI_APPLICATION
> > +
> > +
> > +#
> > +#  VALID_ARCHITECTURES           = RISCV64
> > +#
> > +
> > +[Sources]
> > +  BaseSerialPortLibRiscVSbiLibRam.c
> > +
> > +[Packages]
> > +  MdePkg/MdePkg.dec
> > +
> > +[LibraryClasses]
> > +  RiscVSbiLib
> > diff --git
> > a/MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRiscVSb
> > iLib.c
> > b/MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRiscVSb
> > iLib.c
> > new file mode 100644
> > index 000000000000..0ad5931be3ae
> > --- /dev/null
> > +++ b/MdePkg/Library/BaseSerialPortLibRiscVSbiLib/BaseSerialPortLibRis
> > +++ cVSbiLib.c
> > @@ -0,0 +1,233 @@
> > +/** @file
> > +  Serial Port Library backed by SBI console.
> > +
> > +  Meant for SEC and PEI (XIP) environments.
> > +
> > +  Due to limitations of SBI console interface and XIP environments
> > + (on use of globals), this library instance does not implement
> > + reading  and polling the serial port. See
> > + PrePiDxeSerialPortLibRiscVSbi for  the full-featured variant meant for
> PrePi and DXE environments.
> > +
> > +  Copyright (c) 2023, Intel Corporation. All rights reserved.<BR>
> > +  SPDX-License-Identifier: BSD-2-Clause-Patent
> > +
> > +**/
> > +
> > +#include <Base.h>
> > +#include <Library/SerialPortLib.h>
> > +#include <Library/BaseRiscVSbiLib.h>
> > +
> > +/**
> > +  Initialize the serial device hardware.
> > +
> > +  If no initialization is required, then return RETURN_SUCCESS.
> > +  If the serial device was successfully initialized, then return
> RETURN_SUCCESS.
> > +  If the serial device could not be initialized, then return
> RETURN_DEVICE_ERROR.
> > +
> > +  @retval RETURN_SUCCESS        The serial device was initialized.
> > +  @retval RETURN_DEVICE_ERROR   The serial device could not be
> initialized.
> > +
> > +**/
> > +RETURN_STATUS
> > +EFIAPI
> > +SerialPortInitialize (
> > +  VOID
> > +  )
> > +{
> > +  return RETURN_SUCCESS;
> > +}
> > +
> > +/**
> > +  Write data from buffer to serial device.
> > +
> > +  Writes NumberOfBytes data bytes from Buffer to the serial device.
> > +  The number of bytes actually written to the serial device is returned.
> > +  If the return value is less than NumberOfBytes, then the write operation
> failed.
> > +  If Buffer is NULL, then ASSERT().
> > +  If NumberOfBytes is zero, then return 0.
> > +
> > +  @param  Buffer           The pointer to the data buffer to be written.
> > +  @param  NumberOfBytes    The number of bytes to written to the serial
> device.
> > +
> > +  @retval 0                NumberOfBytes is 0.
> > +  @retval >0               The number of bytes written to the serial device.
> > +                           If this value is less than NumberOfBytes, then the write
> operation failed.
> > +
> > +**/
> > +UINTN
> > +EFIAPI
> > +SerialPortWrite (
> > +  IN UINT8  *Buffer,
> > +  IN UINTN  NumberOfBytes
> > +  )
> > +{
> > +  SBI_RET  Ret;
> > +  UINTN    Index;
> > +
> > +  Ret = SbiCall (SBI_EXT_BASE, SBI_EXT_BASE_PROBE_EXT, 1,
> > + SBI_EXT_DBCN);  if ((TranslateError (Ret.Error) == EFI_SUCCESS) &&
> > +      (Ret.Value != 0))
> > +  {
> > +    Ret = SbiCall (
> > +            SBI_EXT_DBCN,
> > +            SBI_EXT_DBCN_WRITE,
> > +            3,
> > +            NumberOfBytes,
> > +            ((UINTN)Buffer),
> > +            0
> > +            );
> > +    if (TranslateError (Ret.Error) != EFI_SUCCESS) {
> > +      return 0;
> > +    }
> > +
> > +    return Ret.Value;
> > +  }
> > +
> > +  Ret = SbiCall (SBI_EXT_BASE, SBI_EXT_BASE_PROBE_EXT, 1,
> > + SBI_EXT_0_1_CONSOLE_PUTCHAR);  if ((TranslateError (Ret.Error) ==
> EFI_SUCCESS) &&
> > +      (Ret.Value != 0))
> > +  {
> > +    for (Index = 0; Index < NumberOfBytes; Index++) {
> > +      SbiCall (SBI_EXT_0_1_CONSOLE_PUTCHAR, 0, 1, Buffer[Index]);
> What happens if it fails? Shouldn't it return immediately instead of
> continuing with the loop?
> 
> > +    }
> > +
> > +    return Index;
> > +  }
> > +
> > +  /*
> > +   * Neither DBCN or legacy extension were present.
> > +   */
> > +  return NumberOfBytes;
> Isn't it an error? And for earlier DBCN_WRITE error, 0 is returned. So,
> shouldn't we return 0 here also instead of NumberOfBytes?
> 
> Same questions for similar place in other library also.