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/* Project:     OSLib

 * Description: The OS Construction Kit

 * Date:                1.6.2000

 * Idea by:             Luca Abeni & Gerardo Lamastra

 *

 * OSLib is an SO project aimed at developing a common, easy-to-use

 * low-level infrastructure for developing OS kernels and Embedded

 * Applications; it partially derives from the HARTIK project but it

 * currently is independently developed.

 *

 * OSLib is distributed under GPL License, and some of its code has

 * been derived from the Linux kernel source; also some important

 * ideas come from studying the DJGPP go32 extender.

 *

 * We acknowledge the Linux Community, Free Software Foundation,

 * D.J. Delorie and all the other developers who believe in the

 * freedom of software and ideas.

 *

 * For legalese, check out the included GPL license.

 */

/*      Advanced Timer Managment

 *      Author: Giacomo Guidi <giacomo@gandalf.sssup.it>

 */

#include <ll/i386/stdlib.h>

#include <ll/i386/error.h>

#include <ll/i386/advtimer.h>

#include <ll/sys/ll/ll-data.h>

#include <ll/sys/ll/ll-func.h>

#include <ll/i386/pic.h>

#include <ll/sys/ll/event.h>

#include <ll/sys/ll/time.h>

unsigned char use_tsc = 0; //Enable the TSC counter mode

unsigned char use_cmos = 0; //Enable the RTC correction

//Max single delta_clk_per_msec increment

#define MAX_DELTA_INK 10 

//Max delta_clk_per_msec before declare lost

//the CMOS sync

#define MAX_DELTA_TOT 10000

signed long long init_tsc;

signed long long init_nsec; //Warp around 292 years !!

signed long long clk_per_msec;

signed long last_delta_clk_per_msec;

signed long total_delta_clk_per_msec;

unsigned char save_CMOS_regA;

unsigned char save_CMOS_regB;

void HandlerIRQ8(void *p)

{

   unsigned char set;

   static unsigned long init_step = 0;

   signed long long actual_tsc;

   signed long long dt,dn;

   signed long delta_clk_per_msec;

   cli();

   CMOS_READ(0x0C,set);

   rdtscll(actual_tsc);

   //Delta TSC

   dt = actual_tsc - init_tsc;

   init_tsc = actual_tsc;

   UNSIGNED_TSC2NSEC(dt,&dn);

   //Offset

   init_nsec += dn;

   if (init_step < 5) {

           init_step++;

           return;

   }

   dn = dn % 1000000000 - 500000000;

   //Delta clk/msec

   delta_clk_per_msec = dn * clk_per_msec / (500000000 - dn);

   //clk_per_msec adjustment

   if (delta_clk_per_msec < 0) {

        if (delta_clk_per_msec > -MAX_DELTA_INK)

                clk_per_msec += delta_clk_per_msec;

        else

                clk_per_msec -= MAX_DELTA_INK;

   } else {

        if (delta_clk_per_msec < MAX_DELTA_INK)

                clk_per_msec += delta_clk_per_msec;

        else

                clk_per_msec += MAX_DELTA_INK;

   }

   if (delta_clk_per_msec > MAX_DELTA_TOT || delta_clk_per_msec < -MAX_DELTA_TOT) {

           message("Error: Delta_clk_per_msec |%ld| > %ld\n",\

                    (long)delta_clk_per_msec,(long)MAX_DELTA_TOT);

           ll_abort(10);

   }

   last_delta_clk_per_msec = delta_clk_per_msec;

   total_delta_clk_per_msec += delta_clk_per_msec;

   sti();

}

#define HZ 100

#ifdef CONFIG_MELAN

#  define CLOCK_TICK_RATE 1189200 /* AMD Elan has different frequency! */

#else

#  define CLOCK_TICK_RATE 1193180 /* Underlying HZ */

#endif

#define LATCH  ((CLOCK_TICK_RATE + HZ/2) / HZ)

#define CALIBRATE_LATCH (5 * LATCH)

#define CALIBRATE_TIME  (5 * 1000020/HZ)

//TSC Calibration (idea from the linux kernel code)

void ll_calibrate_tsc(void)

{

        signed long long start;

        signed long long end;

        signed long long dtsc;

        signed long start_8253, end_8253, delta_8253;

        cli();

        /* Set the Gate high, disable speaker */

        outp(0x61, (inp(0x61) & ~0x02) | 0x01);

        outp(0x43,0xB0);                        /* binary, mode 0, LSB/MSB, Ch 2 */

        outp(0x42,CALIBRATE_LATCH & 0xff);      /* LSB of count */

        outp(0x42,CALIBRATE_LATCH >> 8);        /* MSB of count */

        rdtscll(start);

        outp(0x43,0x00);

        start_8253 = inp(0x42);

        start_8253 |= inp(0x42) << 8;          

        do {

            outp(0x43,0x00);

            end_8253 = inp(0x42);

            end_8253 |= inp(0x42) << 8;

        } while (end_8253 > 10);

        rdtscll(end);

        outp(0x43,0x00);

        end_8253 = inp(0x42);

        end_8253 |= inp(0x42) << 8;

        //Delta TSC

        dtsc = end - start;

        //Delta PIT

        delta_8253 = start_8253 - end_8253 + 1;

        if (delta_8253 > 0xFFFF) {

                message("Error calculating Delta PIT\n");

                ll_abort(10);

        }

        message("Delta TSC               = %10ld\n",(long)dtsc);

        message("Delta PIT               = %10ld\n",(long)delta_8253);

        clk_per_msec = dtsc * CALIBRATE_LATCH * 1000 / delta_8253 / CALIBRATE_TIME;

        message("Calibrated Clk_per_msec = %10ld\n",(long)clk_per_msec);

        sti();

}

//Low level time read function

void read_timespec(struct timespec *tspec)

{

    signed long long actual_tsc;

    signed long long dt,dn;

    if (clk_per_msec <= 0) {

            NULL_TIMESPEC(tspec);

            return;

    }

    rdtscll(actual_tsc);

    tspec->tsc = actual_tsc;

    dt = actual_tsc - init_tsc;

    UNSIGNED_TSC2NSEC(dt,&dn);

    tspec->tv_sec = (init_nsec + dn) / 1000000000;

    tspec->tv_nsec = (init_nsec + dn) % 1000000000;

}

void ll_init_advtimer()

{

    if (use_tsc) {

        ll_calibrate_tsc();

        last_delta_clk_per_msec = 0;

        total_delta_clk_per_msec = 0;

        rdtscll(init_tsc); // Read start TSC

        init_nsec = 0;

        if (use_cmos) {

            message("CMOS adjustment enabled\n");

            cli();         

            irq_bind(8, HandlerIRQ8, INT_FORCE);

            CMOS_READ(0x0A,save_CMOS_regA);

            CMOS_READ(0x0B,save_CMOS_regB);

            CMOS_WRITE(0x0A,0x2F); // Set 2 Hz Periodic Interrupt

            CMOS_WRITE(0x0B,0x42); // Enable Interrupt

            irq_unmask(8);

            sti();

        }

    } else {

        use_cmos = 0;

   }

}

void restore_CMOS()

{

        if (use_cmos) {

                cli();

                irq_mask(8);

                CMOS_WRITE(0x0A,save_CMOS_regA);

                CMOS_WRITE(0x0B,save_CMOS_regB);

                sti();         

        }

}