Hi Pranav,
On Sun, Jul 19, 2020 at 2:19 PM Pranav Madhu <pranav.ma...@arm.com> wrote:
>
> From: Deepak Pandey <deepak.pan...@arm.com>
>
> A slave error is generated when host accesses the config space of
> non-available device or unimplemented function on a given bus. So
> implement a Neoverse N1 SoC specific PciExpressLib library with a
> workaround to return 0xffffffff for all such access.
>
> This library is inherited from MdePkg/Library/BasePciExpressLib and
> based on commit 9344f0921518 of that library in the tianocore/edk2
> project.
>
> In addition to this, the Neoverse N1 SoC has two other limitations which
> affect the access to the PCIe root port:
> 1. ECAM space is not contiguous, root port ECAM (BDF = 0:0:0) is
> isolated from rest of the downstream hierarchy ECAM space.
> 2. Root port ECAM space is not capable of 8bit/16bit writes.
> This library includes workaround for these limitations as well.
>
> Cc: Ard Biesheuvel <ard.biesheu...@arm.com>
> Cc: Leif Lindholm <l...@nuviainc.com>
> Signed-off-by: Pranav Madhu <pranav.ma...@arm.com>
> ---
> Silicon/ARM/NeoverseN1Soc/NeoverseN1Soc.dec
> | 4 +
>
> Silicon/ARM/NeoverseN1Soc/Library/NeoverseN1SocPciExpressLib/PciExpressLib.inf
> | 56 +
> Silicon/ARM/NeoverseN1Soc/Library/NeoverseN1SocPciExpressLib/PciExpressLib.c
> | 1589 ++++++++++++++++++++
> 3 files changed, 1649 insertions(+)
>
<...>
> +UINT8
> +EFIAPI
> +PciExpressWrite8 (
> + IN UINTN Address,
> + IN UINT8 Value
> + )
> +{
> + UINT8 Bus, Device, Function;
> + UINT8 Offset;
> + UINT32 Data;
> +
> + ASSERT_INVALID_PCI_ADDRESS (Address);
> +
> + Bus = GET_BUS_NUM (Address);
> + Device = GET_DEV_NUM (Address);
> + Function = GET_FUNC_NUM (Address);
> +
> + //
> + // 8-bit and 16-bit writes to root port config space is not supported due
> to
> + // a hardware limitation. As a workaround, perform a read-update-write
> + // sequence on the whole 32-bit word of the root port config register such
> + // that only the specified 8-bits of that word are updated.
> + //
> + if ((Bus == 0) && (Device == 0) && (Function == 0)) {
> + Offset = Address & 0x3;
> + Address &= 0xFFFFFFFC;
> + Data = MmioRead32 ((UINTN)GetPciExpressAddress (Address));
nit: There should have been a space before the GetPciExpressAddress.
This is inconsistent with the rest of the file.
Thanks,
Thomas.
<...>
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