/** @file
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* FdtHelperLib.c
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*
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* Copyright (c) 2021, NUVIA Inc. All rights reserved.
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* Copyright (c) 2020, Linaro Ltd. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-2-Clause-Patent
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*
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**/
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#include <Uefi.h>
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#include <Library/DebugLib.h>
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#include <Library/FdtHelperLib.h>
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#include <Library/PcdLib.h>
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#include <libfdt.h>
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STATIC INT32 mFdtFirstCpuOffset;
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STATIC INT32 mFdtCpuNodeSize;
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/**
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Get MPIDR for a given cpu from device tree passed by Qemu.
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@param [in] CpuId Index of cpu to retrieve MPIDR value for.
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@retval MPIDR value of CPU at index <CpuId>
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**/
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UINT64
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FdtHelperGetMpidr (
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IN UINTN CpuId
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)
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{
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VOID *DeviceTreeBase;
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CONST UINT64 *RegVal;
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INT32 Len;
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DeviceTreeBase = (VOID *)(UINTN)PcdGet64 (PcdDeviceTreeBaseAddress);
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ASSERT (DeviceTreeBase != NULL);
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RegVal = fdt_getprop (DeviceTreeBase,
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mFdtFirstCpuOffset + (CpuId * mFdtCpuNodeSize),
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"reg",
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&Len);
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if (!RegVal) {
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DEBUG ((DEBUG_ERROR, "Couldn't find reg property for CPU:%d\n", CpuId));
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return 0;
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}
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return (fdt64_to_cpu (ReadUnaligned64 (RegVal)));
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}
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/** Walks through the Device Tree created by Qemu and counts the number
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of CPUs present in it.
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@return The number of CPUs present.
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**/
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EFIAPI
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UINT32
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FdtHelperCountCpus (
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VOID
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)
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{
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VOID *DeviceTreeBase;
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INT32 Node;
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INT32 Prev;
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INT32 CpuNode;
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UINT32 CpuCount;
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DeviceTreeBase = (VOID *)(UINTN)PcdGet64 (PcdDeviceTreeBaseAddress);
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ASSERT (DeviceTreeBase != NULL);
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// Make sure we have a valid device tree blob
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ASSERT (fdt_check_header (DeviceTreeBase) == 0);
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CpuNode = fdt_path_offset (DeviceTreeBase, "/cpus");
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if (CpuNode <= 0) {
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DEBUG ((DEBUG_ERROR, "Unable to locate /cpus in device tree\n"));
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return 0;
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}
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CpuCount = 0;
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// Walk through /cpus node and count the number of subnodes.
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// The count of these subnodes corresponds to the number of
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// CPUs created by Qemu.
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Prev = fdt_first_subnode (DeviceTreeBase, CpuNode);
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mFdtFirstCpuOffset = Prev;
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while (1) {
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CpuCount++;
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Node = fdt_next_subnode (DeviceTreeBase, Prev);
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if (Node < 0) {
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break;
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}
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mFdtCpuNodeSize = Node - Prev;
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Prev = Node;
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}
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return CpuCount;
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}
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