mirror of https://github.com/ipxe/ipxe.git
58 lines
1.8 KiB
C
58 lines
1.8 KiB
C
/*
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* Copyright (C) 2016 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <ipxe/nap.h>
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#include <ipxe/efi/efi.h>
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/** @file
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*
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* iPXE CPU sleeping API for EFI
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*
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*/
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/**
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* Sleep until next interrupt
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*
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*/
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static void efiarm_cpu_nap ( void ) {
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/*
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* I can't find any EFI API that allows us to put the CPU to
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* sleep. The CpuSleep() function is defined in CpuLib.h, but
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* isn't part of any exposed protocol so we have no way to
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* call it.
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*
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* The EFI shell doesn't seem to bother sleeping the CPU; it
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* just sits there idly burning power.
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*
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* If a shutdown is in progess, there may be nothing to
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* generate an interrupt since the timer is disabled in the
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* first step of ExitBootServices().
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*/
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if ( ! efi_shutdown_in_progress )
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__asm__ __volatile__ ( "wfi" );
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}
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PROVIDE_NAP ( efiarm, cpu_nap, efiarm_cpu_nap );
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