rdtsc_timer.c File Reference

RDTSC timer. More...

#include <assert.h>
#include <gpxe/timer.h>
#include <gpxe/timer2.h>

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER)
static void	rdtsc_udelay (unsigned long usecs)
	Delay for a fixed number of microseconds.
static unsigned long	rdtsc_ticks_per_sec (void)
	Get number of ticks per second.
	PROVIDE_TIMER (rdtsc, udelay, rdtsc_udelay)
	PROVIDE_TIMER_INLINE (rdtsc, currticks)
	PROVIDE_TIMER (rdtsc, ticks_per_sec, rdtsc_ticks_per_sec)
Variables
static unsigned long	rdtsc_ticks_per_usec
	Number of TSC ticks per microsecond.

---

Detailed Description

RDTSC timer.

Definition in file rdtsc_timer.c.

---

Function Documentation

FILE_LICENCE

(

GPL2_OR_LATER

)

static void rdtsc_udelay

(

unsigned long

usecs

)

[static]

Delay for a fixed number of microseconds.

Parameters:

usecs

Number of microseconds for which to delay

Definition at line 43 of file rdtsc_timer.c.

References currticks(), DBG, rdtsc_ticks_per_usec, timer2_udelay(), and TSC_SHIFT.

                                                 {
        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 ) );
        }
}

static unsigned long rdtsc_ticks_per_sec

(

void

)

[static]

Get number of ticks per second.

Return values:

ticks_per_sec

Number of ticks per second

Definition at line 75 of file rdtsc_timer.c.

References assert, rdtsc_ticks_per_usec, and udelay().

                                                  {

        /* 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
	)

---

Variable Documentation

unsigned long rdtsc_ticks_per_usec [static]

Number of TSC ticks per microsecond.

This is calibrated on the first use of the timer.

Definition at line 36 of file rdtsc_timer.c.

Referenced by rdtsc_ticks_per_sec(), and rdtsc_udelay().