Add qemu 2.4.0

[kvmfornfv.git] / qemu / roms / ipxe / src / arch / i386 / core / rdtsc_timer.c

diff --git a/qemu/roms/ipxe/src/arch/i386/core/rdtsc_timer.c b/qemu/roms/ipxe/src/arch/i386/core/rdtsc_timer.c
new file mode 100644 (file)
index 0000000..2f31afc
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+++ b/qemu/roms/ipxe/src/arch/i386/core/rdtsc_timer.c
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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 );
+
+/** @file
+ *
+ * RDTSC timer
+ *
+ */
+
+#include <assert.h>
+#include <ipxe/timer.h>
+#include <ipxe/timer2.h>
+
+/**
+ * Number of TSC ticks per microsecond
+ *
+ * This is calibrated on the first use of the timer.
+ */
+static unsigned long rdtsc_ticks_per_usec;
+
+/**
+ * Delay for a fixed number of microseconds
+ *
+ * @v usecs            Number of microseconds for which to delay
+ */
+static void rdtsc_udelay ( unsigned long usecs ) {
+       unsigned long start;
+       unsigned long elapsed;
+
+       /* Sanity guard, since we may divide by this */
+       if ( ! usecs )
+               usecs = 1;
+
+       start = currticks();
+       if ( rdtsc_ticks_per_usec ) {
+               /* Already calibrated; busy-wait until done */
+               do {
+                       elapsed = ( currticks() - start );
+               } while ( elapsed < ( usecs * rdtsc_ticks_per_usec ) );
+       } else {
+               /* Not yet calibrated; use timer2 and calibrate
+                * based on result.
+                */
+               timer2_udelay ( usecs );
+               elapsed = ( currticks() - start );
+               rdtsc_ticks_per_usec = ( elapsed / usecs );
+               DBG ( "RDTSC timer calibrated: %ld ticks in %ld usecs "
+                     "(%ld MHz)\n", elapsed, usecs,
+                     ( rdtsc_ticks_per_usec << TSC_SHIFT ) );
+       }
+}
+
+/**
+ * Get number of ticks per second
+ *
+ * @ret ticks_per_sec  Number of ticks per second
+ */
+static unsigned long rdtsc_ticks_per_sec ( void ) {
+
+       /* Calibrate timer, if not already done */
+       if ( ! rdtsc_ticks_per_usec )
+               udelay ( 1 );
+
+       /* Sanity check */
+       assert ( rdtsc_ticks_per_usec != 0 );
+
+       return ( rdtsc_ticks_per_usec * 1000 * 1000 );
+}
+
+PROVIDE_TIMER ( rdtsc, udelay, rdtsc_udelay );
+PROVIDE_TIMER_INLINE ( rdtsc, currticks );
+PROVIDE_TIMER ( rdtsc, ticks_per_sec, rdtsc_ticks_per_sec );