On Thu, Feb 18, 2021 at 20:57:39 -0700, Rebecca Cran wrote:
> The CountCpusFromFdt function is now used in two places. Create
> FdtHelperLib for this and similar functions.
>
> Signed-off-by: Rebecca Cran <rebe...@nuviainc.com>
Reviewed-by: Leif Lindholm <l...@nuviainc.com>
One comment below, you can fold in or not and still keep the reviewed-by.
> ---
> Platform/Qemu/SbsaQemu/SbsaQemu.dsc | 2 +
> Silicon/Qemu/SbsaQemu/Include/Library/FdtHelperLib.h | 24 +++++++
> Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.c | 69
> ++++++++++++++++++++
> Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.inf | 28 ++++++++
> 4 files changed, 123 insertions(+)
>
> diff --git a/Platform/Qemu/SbsaQemu/SbsaQemu.dsc
> b/Platform/Qemu/SbsaQemu/SbsaQemu.dsc
> index f6af3f9111ee..8faad3eda217 100644
> --- a/Platform/Qemu/SbsaQemu/SbsaQemu.dsc
> +++ b/Platform/Qemu/SbsaQemu/SbsaQemu.dsc
> @@ -121,6 +121,8 @@ DEFINE NETWORK_HTTP_BOOT_ENABLE = FALSE
> # ARM PL011 UART Driver
> PL011UartLib|ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.inf
>
> + FdtHelperLib|Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.inf
> +
> # Debug Support
>
> PeCoffExtraActionLib|ArmPkg/Library/DebugPeCoffExtraActionLib/DebugPeCoffExtraActionLib.inf
> DebugAgentLib|MdeModulePkg/Library/DebugAgentLibNull/DebugAgentLibNull.inf
> diff --git a/Silicon/Qemu/SbsaQemu/Include/Library/FdtHelperLib.h
> b/Silicon/Qemu/SbsaQemu/Include/Library/FdtHelperLib.h
> new file mode 100644
> index 000000000000..eac47349a3d7
> --- /dev/null
> +++ b/Silicon/Qemu/SbsaQemu/Include/Library/FdtHelperLib.h
> @@ -0,0 +1,24 @@
> +/** @file
> +* FdtHelperLib.h
> +*
> +* Copyright (c) 2021, NUVIA Inc. All rights reserved.
> +*
> +* SPDX-License-Identifier: BSD-2-Clause-Patent
> +*
> +**/
> +
> +#ifndef FDT_HELPER_LIB_
> +#define FDT_HELPER_LIB_
> +
> +/** Walks through the Device Tree created by Qemu and counts the number
> + of CPUs present in it.
> +
> + @return The number of CPUs present.
> +**/
> +EFIAPI
> +UINT16
There is no inherent need to restrict this function to a 16-bit return
value (and on RISC architectures, this generally means extra masking
going on).
Indeed, the implementation uses a 32-bit value, then returns the
bottom 16 bits of that.
I guess this ends up going into a 16-bit field somewhere else?
Another way to deal with that would be to take the full 32-bit value
and ASSERT at the point of stuffing the table.
/
Leif
> +CountCpusFromFdt (
> + VOID
> + );
> +
> +#endif /* FDT_HELPER_LIB_ */
> diff --git a/Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.c
> b/Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.c
> new file mode 100644
> index 000000000000..c399fec5f9c7
> --- /dev/null
> +++ b/Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.c
> @@ -0,0 +1,69 @@
> +/** @file
> +* FdtHelperLib.c
> +*
> +* Copyright (c) 2021, NUVIA Inc. All rights reserved.
> +* Copyright (c) 2020, Linaro Ltd. All rights reserved.
> +*
> +* SPDX-License-Identifier: BSD-2-Clause-Patent
> +*
> +**/
> +
> +
> +/** Walks through the Device Tree created by Qemu and counts the number
> + of CPUs present in it.
> +
> + @return The number of CPUs present.
> +**/
> +
> +#include <Uefi.h>
> +#include <Library/DebugLib.h>
> +#include <Library/FdtHelperLib.h>
> +#include <Library/PcdLib.h>
> +#include <libfdt.h>
> +
> +/** Walks through the Device Tree created by Qemu and counts the number
> + of CPUs present in it.
> +
> + @return The number of CPUs present.
> +**/
> +EFIAPI
> +UINT16
> +CountCpusFromFdt (
> + VOID
> + )
> +{
> + VOID *DeviceTreeBase;
> + INT32 Node;
> + INT32 Prev;
> + INT32 CpuNode;
> + INT32 CpuCount;
> +
> + DeviceTreeBase = (VOID *)(UINTN)PcdGet64 (PcdDeviceTreeBaseAddress);
> + ASSERT (DeviceTreeBase != NULL);
> +
> + // Make sure we have a valid device tree blob
> + ASSERT (fdt_check_header (DeviceTreeBase) == 0);
> +
> + CpuNode = fdt_path_offset (DeviceTreeBase, "/cpus");
> + if (CpuNode <= 0) {
> + DEBUG ((DEBUG_ERROR, "Unable to locate /cpus in device tree\n"));
> + return 0;
> + }
> +
> + CpuCount = 0;
> +
> + // Walk through /cpus node and count the number of subnodes.
> + // The count of these subnodes corresponds to the number of
> + // CPUs created by Qemu.
> + Prev = fdt_first_subnode (DeviceTreeBase, CpuNode);
> + while (1) {
> + CpuCount++;
> + Node = fdt_next_subnode (DeviceTreeBase, Prev);
> + if (Node < 0) {
> + break;
> + }
> + Prev = Node;
> + }
> +
> + return CpuCount;
> +}
> diff --git a/Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.inf
> b/Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.inf
> new file mode 100644
> index 000000000000..d84c16f888d1
> --- /dev/null
> +++ b/Silicon/Qemu/SbsaQemu/Library/FdtHelperLib/FdtHelperLib.inf
> @@ -0,0 +1,28 @@
> +#/** @file
> +#
> +# Component description file for FdtHelperLib module
> +#
> +# Copyright (c) 2021, NUVIA Inc. All rights reserved.
> +#
> +# SPDX-License-Identifier: BSD-2-Clause-Patent
> +#
> +#**/
> +
> +[Defines]
> + INF_VERSION = 1.29
> + BASE_NAME = FdtHelperLib
> + FILE_GUID = 34e4396f-c2fc-4f9e-ad58-0f98e99e3875
> + MODULE_TYPE = BASE
> + VERSION_STRING = 1.0
> + LIBRARY_CLASS = FdtHelperLib
> +
> +[Sources.common]
> + FdtHelperLib.c
> +
> +[Packages]
> + EmbeddedPkg/EmbeddedPkg.dec
> + MdePkg/MdePkg.dec
> + Silicon/Qemu/SbsaQemu/SbsaQemu.dec
> +
> +[FixedPcd]
> + gArmVirtSbsaQemuPlatformTokenSpaceGuid.PcdDeviceTreeBaseAddress
> --
> 2.26.2
>
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