Re: [PATCH 1/2] ArmPlatformPkg: PL011 Dynamic clock freq Support

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Hello Udit,

Apologies for not bringing this up the first time, but I have some
additional comments. The first time around, I only had a cursory look
because at that point I was still skeptical whether we needed this
library in the first place.

On 5 June 2018 at 19:59, Udit Kumar <udit.kumar@nxp.com> wrote:
> Some platform support dynamic clocking, Which is controlled
> by some jumper setting or hardware registers.
> Result of that PCD PL011UartClkInHz needs to be updated for
> frequency change.
> This patch implements support for dynamic frequency for
> PL011 uart.
> This patch implements default lib, which is using Pcd.
> Platform which needs dynamic clocking needs implement
> PL011UartClockLib
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Udit Kumar <udit.kumar@nxp.com>
> ---
>  ArmPlatformPkg/ArmPlatformPkg.dec                  |  1 +
>  ArmPlatformPkg/Include/Library/PL011UartClockLib.h | 32 +++++++++++++++++++
>  .../Library/PL011UartClockLib/PL011UartClockLib.c  | 29 +++++++++++++++++
>  .../PL011UartClockLib/PL011UartClockLib.inf        | 37 ++++++++++++++++++++++

Please add a reference to the new library in the [Components] section
of ArmPlatformPkg.dsc as well, so we can build it standalone.

>  4 files changed, 99 insertions(+)
>  create mode 100644 ArmPlatformPkg/Include/Library/PL011UartClockLib.h
>  create mode 100644 ArmPlatformPkg/Library/PL011UartClockLib/PL011UartClockLib.c
>  create mode 100644 ArmPlatformPkg/Library/PL011UartClockLib/PL011UartClockLib.inf
>
> diff --git a/ArmPlatformPkg/ArmPlatformPkg.dec b/ArmPlatformPkg/ArmPlatformPkg.dec
> index dff4598..5f67e74 100644
> --- a/ArmPlatformPkg/ArmPlatformPkg.dec
> +++ b/ArmPlatformPkg/ArmPlatformPkg.dec
> @@ -36,6 +36,7 @@
>    LcdHwLib|Include/Library/LcdHwLib.h
>    LcdPlatformLib|Include/Library/LcdPlatformLib.h
>    NorFlashPlatformLib|Include/Library/NorFlashPlatformLib.h
> +  PL011UartClockLib|Include/Library/PL011UartClockLib.h
>    PL011UartLib|Include/Library/PL011UartLib.h
>
>  [Guids.common]
> diff --git a/ArmPlatformPkg/Include/Library/PL011UartClockLib.h b/ArmPlatformPkg/Include/Library/PL011UartClockLib.h
> new file mode 100644
> index 0000000..93813a0
> --- /dev/null
> +++ b/ArmPlatformPkg/Include/Library/PL011UartClockLib.h
> @@ -0,0 +1,32 @@
> +/** @file
> +*
> +*  Copyright 2018 NXP
> +*
> +*  This program and the accompanying materials
> +*  are licensed and made available under the terms and conditions of the BSD License
> +*  which accompanies this distribution.  The full text of the license may be found at
> +*  http://opensource.org/licenses/bsd-license.php
> +*
> +*  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +*  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +*
> +**/
> +
> +#ifndef __PL011CLOCKLIB_H__
> +#define __PL011CLOCKLIB_H__

Nit: use __PL011UARTCLOCKLIB_H__ to match the filename.

> +
> +
> +/**
> +  Return frequency of PL011.
> +

Mention the baud clock?
> +  By default this function returns FixedPcdGet32 (PL011UartClkInHz)
> +

Drop this line please, it is not part of the prototype

> +  @return Return frequency of PL011
> +
> +**/
> +UINT32
> +ArmPlatformGetPL011ClockFreq (

The ArmPlatform prefix is unnecessary here: please use
PL011UartClockGetFreq() instead.

> +  VOID
> +  );
> +
> +#endif
> diff --git a/ArmPlatformPkg/Library/PL011UartClockLib/PL011UartClockLib.c b/ArmPlatformPkg/Library/PL011UartClockLib/PL011UartClockLib.c
> new file mode 100644
> index 0000000..b56af14
> --- /dev/null
> +++ b/ArmPlatformPkg/Library/PL011UartClockLib/PL011UartClockLib.c
> @@ -0,0 +1,29 @@
> +/** @file
> +*
> +*  Copyright 2018 NXP
> +*
> +*  This program and the accompanying materials
> +*  are licensed and made available under the terms and conditions of the BSD License
> +*  which accompanies this distribution.  The full text of the license may be found at
> +*  http://opensource.org/licenses/bsd-license.php
> +*
> +*  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +*  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +*
> +**/
> +
> +#include <Library/PL011UartClockLib.h>
> +
> +/**
> +  Return clock in for PL011 Uart IP.
> +**/
> +UINT32

Please add EFIAPI even if it is defined to an empty string when using GCC/ARM.

> +ArmPlatformGetPL011ClockFreq (
> +  VOID
> +  )
> +{
> +  // This function needs to be implemented on platforms which supports
> +  // dynamic clocking to avoid re-building of UEFI firmware for PL011
> +  // clock change

Please drop this comment, it does not belong here. You can add
something along these lines in the declaration of the library class if
you want, but you can drop it altogether IMO.

> +  return FixedPcdGet32 (PL011UartClkInHz);
> +}
> diff --git a/ArmPlatformPkg/Library/PL011UartClockLib/PL011UartClockLib.inf b/ArmPlatformPkg/Library/PL011UartClockLib/PL011UartClockLib.inf
> new file mode 100644
> index 0000000..5f6f699
> --- /dev/null
> +++ b/ArmPlatformPkg/Library/PL011UartClockLib/PL011UartClockLib.inf
> @@ -0,0 +1,37 @@
> +#/* @file
> +#  Copyright 2018 NXP
> +#
> +#  This program and the accompanying materials
> +#  are licensed and made available under the terms and conditions of the BSD License
> +#  which accompanies this distribution.  The full text of the license may be found at
> +#  http://opensource.org/licenses/bsd-license.php
> +#
> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +#
> +#*/
> +
> +[Defines]
> +  INF_VERSION                    = 0x0001000A

Please use 0x0001001A

> +  BASE_NAME                      = PL011UartClockLib

EDK2 usually has a BaseXxxLib implementation and does not reuse the
library class name for the base implementation, so I am fine with
this. Leif?


> +  FILE_GUID                      = af8fef24-afbb-472a-b8b7-13101a79703c
> +  MODULE_TYPE                    = BASE
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = PL011UartClockLib
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +  MdeModulePkg/MdeModulePkg.dec

Is this line needed?

> +  ArmPkg/ArmPkg.dec
> +  ArmPlatformPkg/ArmPlatformPkg.dec
> +

Sort alphabetically please.

> +[LibraryClasses]
> +  ArmLib
> +  DebugLib
> +
> +[Sources.common]
> +  PL011UartClockLib.c
> +
> +[FixedPcd]
> +  gArmPlatformTokenSpaceGuid.PL011UartClkInHz
> +
> --
> 1.9.1
>