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Subject: Re: [PATCH edk2-platforms 10/16] Silicon/NXP: PciSegmentLib: Add ECAM config support for PCIe LS Controller
To: Wasim Khan <wasim.khan@oss.nxp.com>, devel@edk2.groups.io,
 meenakshi.aggarwal@nxp.com, vabhav.sharma@nxp.com, V.Sethi@nxp.com,
 leif@nuviainc.com, jon@solid-run.com
Cc: Wasim Khan <wasim.khan@nxp.com>
References: <1590102139-16588-1-git-send-email-wasim.khan@oss.nxp.com>
 <1590102139-16588-11-git-send-email-wasim.khan@oss.nxp.com>
From: "Ard Biesheuvel" <ard.biesheuvel@arm.com>
Message-ID: <255bb5ca-a094-fc99-a327-c902a6258286@arm.com>
Date: Fri, 22 May 2020 11:36:17 +0200
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On 5/22/20 1:02 AM, Wasim Khan wrote:
> From: Wasim Khan <wasim.khan@nxp.com>
> 
> PCIe Layerscape controller can be enabled for ECAM style
> configuration access using CFG SHIFT Feature.
> 
> Check for PcdPciCfgShiftEnable to decide the configuration access
> scheme to be used with PCIe LS controller.
> 
> Signed-off-by: Wasim Khan <wasim.khan@nxp.com>
> ---
>   Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.inf |  3 +++
>   Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.c   | 20 ++++++++++++++++----
>   2 files changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.inf b/Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.inf
> index a36e79239b33..936213dc8a9d 100755
> --- a/Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.inf
> +++ b/Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.inf
> @@ -30,3 +30,6 @@ [LibraryClasses]
>   
>   [FixedPcd]
>     gNxpQoriqLsTokenSpaceGuid.PcdPciExp1BaseAddr
> +
> +[Pcd]
> +  gNxpQoriqLsTokenSpaceGuid.PcdPciCfgShiftEnable
> diff --git a/Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.c b/Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.c
> index ecd36971b753..552a425c6832 100755
> --- a/Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.c
> +++ b/Silicon/NXP/Library/PciSegmentLib/PciSegmentLib.c
> @@ -34,6 +34,8 @@ typedef enum {
>   #define ASSERT_INVALID_PCI_SEGMENT_ADDRESS(A,M) \
>     ASSERT (((A) & (0xffff0000f0000000ULL | (M))) == 0)
>   
> +static BOOLEAN CfgShiftEnable;
> +

This is a compile time constant, right? Please try to avoid using 
runtime read/write variables in that case, since it defeats the 
compiler's ability to remove code that is never executed.


>   STATIC
>   UINT64
>   PciLsCfgTarget (
> @@ -88,11 +90,20 @@ PciLsGetConfigBase (
>   {
>     UINT32 CfgAddr;
>   
> -  CfgAddr = (UINT16)Offset;
> -  if (Bus) {
> -    return PciLsCfgTarget (PCI_SEG0_DBI_BASE + PCI_DBI_SIZE_DIFF * Segment, Address, Segment, Bus, Offset);
> +  if (CfgShiftEnable) {
> +    CfgAddr = (UINT32)Address;
> +    if (Bus) {
> +      return PCI_SEG0_MMIO_MEMBASE + PCI_BASE_DIFF * Segment + CfgAddr;
> +    } else {
> +      return PCI_SEG0_DBI_BASE + PCI_DBI_SIZE_DIFF * Segment + CfgAddr;
> +    }
>     } else {
> -    return PCI_SEG0_DBI_BASE + PCI_DBI_SIZE_DIFF * Segment + CfgAddr;
> +    CfgAddr = (UINT16)Offset;
> +    if (Bus) {
> +      return PciLsCfgTarget (PCI_SEG0_DBI_BASE + PCI_DBI_SIZE_DIFF * Segment, Address, Segment, Bus, Offset);
> +    } else {
> +      return PCI_SEG0_DBI_BASE + PCI_DBI_SIZE_DIFF * Segment + CfgAddr;
> +    }
>     }
>   }
>   
> @@ -608,5 +619,6 @@ PciSegLibInit (
>     IN EFI_SYSTEM_TABLE  *SystemTable
>     )
>   {
> +  CfgShiftEnable = CFG_SHIFT_ENABLE;
>     return EFI_SUCCESS;
>   }
>