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- /*
- * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
- * 02110-1301, USA.
- */
-
- FILE_LICENCE ( GPL2_OR_LATER );
-
- #include <limits.h>
- #include <assert.h>
- #include <unistd.h>
- #include <ipxe/timer.h>
- #include <ipxe/efi/efi.h>
- #include <ipxe/efi/Protocol/Cpu.h>
-
- /** @file
- *
- * iPXE timer API for EFI
- *
- */
-
- /** Scale factor to apply to CPU timer 0
- *
- * The timer is scaled down in order to ensure that reasonable values
- * for "number of ticks" don't exceed the size of an unsigned long.
- */
- #define EFI_TIMER0_SHIFT 12
-
- /** Calibration time */
- #define EFI_CALIBRATE_DELAY_MS 1
-
- /** CPU protocol */
- static EFI_CPU_ARCH_PROTOCOL *cpu_arch;
- EFI_REQUIRE_PROTOCOL ( EFI_CPU_ARCH_PROTOCOL, &cpu_arch );
-
- /**
- * Delay for a fixed number of microseconds
- *
- * @v usecs Number of microseconds for which to delay
- */
- static void efi_udelay ( unsigned long usecs ) {
- EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
- EFI_STATUS efirc;
-
- if ( ( efirc = bs->Stall ( usecs ) ) != 0 ) {
- DBG ( "EFI could not delay for %ldus: %s\n",
- usecs, efi_strerror ( efirc ) );
- /* Probably screwed */
- }
- }
-
- /**
- * Get current system time in ticks
- *
- * @ret ticks Current time, in ticks
- */
- static unsigned long efi_currticks ( void ) {
- UINT64 time;
- EFI_STATUS efirc;
-
- /* Read CPU timer 0 (TSC) */
- if ( ( efirc = cpu_arch->GetTimerValue ( cpu_arch, 0, &time,
- NULL ) ) != 0 ) {
- DBG ( "EFI could not read CPU timer: %s\n",
- efi_strerror ( efirc ) );
- /* Probably screwed */
- return -1UL;
- }
-
- return ( time >> EFI_TIMER0_SHIFT );
- }
-
- /**
- * Get number of ticks per second
- *
- * @ret ticks_per_sec Number of ticks per second
- */
- static unsigned long efi_ticks_per_sec ( void ) {
- static unsigned long ticks_per_sec = 0;
-
- /* Calibrate timer, if necessary. EFI does nominally provide
- * the timer speed via the (optional) TimerPeriod parameter to
- * the GetTimerValue() call, but it gets the speed slightly
- * wrong. By up to three orders of magnitude. Not helpful.
- */
- if ( ! ticks_per_sec ) {
- unsigned long start;
- unsigned long elapsed;
-
- DBG ( "Calibrating EFI timer with a %d ms delay\n",
- EFI_CALIBRATE_DELAY_MS );
- start = currticks();
- mdelay ( EFI_CALIBRATE_DELAY_MS );
- elapsed = ( currticks() - start );
- ticks_per_sec = ( elapsed * ( 1000 / EFI_CALIBRATE_DELAY_MS ));
- DBG ( "EFI CPU timer calibrated at %ld ticks in %d ms (%ld "
- "ticks/sec)\n", elapsed, EFI_CALIBRATE_DELAY_MS,
- ticks_per_sec );
- }
-
- return ticks_per_sec;
- }
-
- PROVIDE_TIMER ( efi, udelay, efi_udelay );
- PROVIDE_TIMER ( efi, currticks, efi_currticks );
- PROVIDE_TIMER ( efi, ticks_per_sec, efi_ticks_per_sec );
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