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/*
 *  include/asm-i386/mach-default/mach_timer.h
 *
 *  Machine specific calibrate_tsc() for generic.
 *  Split out from timer_tsc.c by Osamu Tomita <tomita@cinet.co.jp>
 */
/* ------ Calibrate the TSC -------
 * Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
 * Too much 64-bit arithmetic here to do this cleanly in C, and for
 * accuracy's sake we want to keep the overhead on the CTC speaker (channel 2)
 * output busy loop as low as possible. We avoid reading the CTC registers
 * directly because of the awkward 8-bit access mechanism of the 82C54
 * device.
 */
#ifndef _MACH_TIMER_H
#define _MACH_TIMER_H

#define CALIBRATE_LATCH (5 * LATCH)

static inline void mach_prepare_counter(void)
{
       /* Set the Gate high, disable speaker */
        outb((inb(0x61) & ~0x02) | 0x01, 0x61);

        /*
         * Now let's take care of CTC channel 2
         *
         * Set the Gate high, program CTC channel 2 for mode 0,
         * (interrupt on terminal count mode), binary count,
         * load 5 * LATCH count, (LSB and MSB) to begin countdown.
         *
         * Some devices need a delay here.
         */
        outb(0xb0, 0x43);                       /* binary, mode 0, LSB/MSB, Ch 2 */
        outb_p(CALIBRATE_LATCH & 0xff, 0x42);   /* LSB of count */
        outb_p(CALIBRATE_LATCH >> 8, 0x42);       /* MSB of count */
}

static inline void mach_countup(unsigned long *count_p)
{
        unsigned long count = 0;
        do {
                count++;
        } while ((inb_p(0x61) & 0x20) == 0);
        *count_p = count;
}

#endif /* !_MACH_TIMER_H */