8406115834
Access to the gpxe.org and etherboot.org domains and associated resources has been revoked by the registrant of the domain. Work around this problem by renaming project from gPXE to iPXE, and updating URLs to match. Also update README, LOG and COPYRIGHTS to remove obsolete information. Signed-off-by: Michael Brown <mcb30@ipxe.org>
119 lines
3.2 KiB
C
119 lines
3.2 KiB
C
/*
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* Copyright (C) 2008 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., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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#include <limits.h>
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#include <assert.h>
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#include <unistd.h>
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#include <ipxe/timer.h>
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#include <ipxe/efi/efi.h>
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#include <ipxe/efi/Protocol/Cpu.h>
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/** @file
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*
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* iPXE timer API for EFI
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*
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*/
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/** Scale factor to apply to CPU timer 0
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*
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* The timer is scaled down in order to ensure that reasonable values
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* for "number of ticks" don't exceed the size of an unsigned long.
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*/
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#define EFI_TIMER0_SHIFT 12
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/** Calibration time */
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#define EFI_CALIBRATE_DELAY_MS 1
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/** CPU protocol */
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static EFI_CPU_ARCH_PROTOCOL *cpu_arch;
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EFI_REQUIRE_PROTOCOL ( EFI_CPU_ARCH_PROTOCOL, &cpu_arch );
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/**
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* Delay for a fixed number of microseconds
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*
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* @v usecs Number of microseconds for which to delay
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*/
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static void efi_udelay ( unsigned long usecs ) {
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EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
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EFI_STATUS efirc;
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if ( ( efirc = bs->Stall ( usecs ) ) != 0 ) {
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DBG ( "EFI could not delay for %ldus: %s\n",
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usecs, efi_strerror ( efirc ) );
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/* Probably screwed */
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}
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}
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/**
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* Get current system time in ticks
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*
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* @ret ticks Current time, in ticks
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*/
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static unsigned long efi_currticks ( void ) {
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UINT64 time;
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EFI_STATUS efirc;
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/* Read CPU timer 0 (TSC) */
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if ( ( efirc = cpu_arch->GetTimerValue ( cpu_arch, 0, &time,
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NULL ) ) != 0 ) {
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DBG ( "EFI could not read CPU timer: %s\n",
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efi_strerror ( efirc ) );
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/* Probably screwed */
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return -1UL;
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}
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return ( time >> EFI_TIMER0_SHIFT );
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}
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/**
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* Get number of ticks per second
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*
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* @ret ticks_per_sec Number of ticks per second
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*/
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static unsigned long efi_ticks_per_sec ( void ) {
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static unsigned long ticks_per_sec = 0;
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/* Calibrate timer, if necessary. EFI does nominally provide
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* the timer speed via the (optional) TimerPeriod parameter to
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* the GetTimerValue() call, but it gets the speed slightly
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* wrong. By up to three orders of magnitude. Not helpful.
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*/
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if ( ! ticks_per_sec ) {
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unsigned long start;
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unsigned long elapsed;
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DBG ( "Calibrating EFI timer with a %d ms delay\n",
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EFI_CALIBRATE_DELAY_MS );
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start = currticks();
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mdelay ( EFI_CALIBRATE_DELAY_MS );
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elapsed = ( currticks() - start );
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ticks_per_sec = ( elapsed * ( 1000 / EFI_CALIBRATE_DELAY_MS ));
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DBG ( "EFI CPU timer calibrated at %ld ticks in %d ms (%ld "
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"ticks/sec)\n", elapsed, EFI_CALIBRATE_DELAY_MS,
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ticks_per_sec );
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}
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return ticks_per_sec;
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}
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PROVIDE_TIMER ( efi, udelay, efi_udelay );
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PROVIDE_TIMER ( efi, currticks, efi_currticks );
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PROVIDE_TIMER ( efi, ticks_per_sec, efi_ticks_per_sec );
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