/*
 * (C) Copyright 2003
 * Texas Instruments <www.ti.com>
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Marius Groeger <mgroeger@sysgo.de>
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Alex Zuepke <azu@sysgo.de>
 *
 * (C) Copyright 2002-2004
 * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
 *
 * (C) Copyright 2004
 * Philippe Robin, ARM Ltd. <philippe.robin@arm.com>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * 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 (at your option) 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., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include <arm926ejs.h>

#define TIMER_LOAD_VAL 0xffffffff

/* macro to read the 32 bit timer */
#define READ_TIMER (*(volatile ulong *)(CONFIG_SYS_TIMERBASE+4))

static ulong timestamp;
static ulong lastdec;

#define TIMER_ENABLE    (1 << 7)
#define TIMER_MODE_MSK  (1 << 6)
#define TIMER_MODE_FR   (0 << 6)
#define TIMER_MODE_PD   (1 << 6)

#define TIMER_INT_EN    (1 << 5)
#define TIMER_PRS_MSK   (3 << 2)
#define TIMER_PRS_8S    (1 << 3)
#define TIMER_SIZE_MSK  (1 << 2)
#define TIMER_ONE_SHT   (1 << 0)

int timer_init (void)
{
        ulong   tmr_ctrl_val;

        /* 1st disable the Timer */
        tmr_ctrl_val = *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8);
        tmr_ctrl_val &= ~TIMER_ENABLE;
        *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = tmr_ctrl_val;

        /*
         * The Timer Control Register has one Undefined/Shouldn't Use Bit
         * So we should do read/modify/write Operation
         */

        /*
         * Timer Mode : Free Running
         * Interrupt : Disabled
         * Prescale : 8 Stage, Clk/256
         * Tmr Siz : 16 Bit Counter
         * Tmr in Wrapping Mode
         */
        tmr_ctrl_val = *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8);
        tmr_ctrl_val &= ~(TIMER_MODE_MSK | TIMER_INT_EN | TIMER_PRS_MSK | TIMER_SIZE_MSK | TIMER_ONE_SHT );
        tmr_ctrl_val |= (TIMER_ENABLE | TIMER_PRS_8S);

        *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = tmr_ctrl_val;

        /* init the timestamp and lastdec value */
        reset_timer_masked();

        return 0;
}

/*
 * timer without interrupts
 */

void reset_timer (void)
{
        reset_timer_masked ();
}

ulong get_timer (ulong base)
{
        return get_timer_masked () - base;
}

void set_timer (ulong t)
{
        timestamp = t;
}

/* delay x useconds AND perserve advance timstamp value */
void udelay (unsigned long usec)
{
        ulong tmo, tmp;

        if(usec >= 1000){               /* if "big" number, spread normalization to seconds */
                tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
                tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
                tmo /= 1000;            /* finish normalize. */
        }else{                          /* else small number, don't kill it prior to HZ multiply */
                tmo = usec * CONFIG_SYS_HZ;
                tmo /= (1000*1000);
        }

        tmp = get_timer (0);            /* get current timestamp */
        if( (tmo + tmp + 1) < tmp )     /* if setting this fordward will roll time stamp */
                reset_timer_masked ();  /* reset "advancing" timestamp to 0, set lastdec value */
        else
                tmo += tmp;             /* else, set advancing stamp wake up time */

        while (get_timer_masked () < tmo)/* loop till event */
                /*NOP*/;
}

void reset_timer_masked (void)
{
        /* reset time */
        lastdec = READ_TIMER;  /* capure current decrementer value time */
        timestamp = 0;         /* start "advancing" time stamp from 0 */
}

ulong get_timer_masked (void)
{
        ulong now = READ_TIMER;         /* current tick value */

        if (lastdec >= now) {           /* normal mode (non roll) */
                /* normal mode */
                timestamp += lastdec - now; /* move stamp fordward with absoulte diff ticks */
        } else {                        /* we have overflow of the count down timer */
                /* nts = ts + ld + (TLV - now)
                 * ts=old stamp, ld=time that passed before passing through -1
                 * (TLV-now) amount of time after passing though -1
                 * nts = new "advancing time stamp"...it could also roll and cause problems.
                 */
                timestamp += lastdec + TIMER_LOAD_VAL - now;
        }
        lastdec = now;

        return timestamp;
}

/* waits specified delay value and resets timestamp */
void udelay_masked (unsigned long usec)
{
        ulong tmo;
        ulong endtime;
        signed long diff;

        if (usec >= 1000) {             /* if "big" number, spread normalization to seconds */
                tmo = usec / 1000;      /* start to normalize for usec to ticks per sec */
                tmo *= CONFIG_SYS_HZ;           /* find number of "ticks" to wait to achieve target */
                tmo /= 1000;            /* finish normalize. */
        } else {                        /* else small number, don't kill it prior to HZ multiply */
                tmo = usec * CONFIG_SYS_HZ;
                tmo /= (1000*1000);
        }

        endtime = get_timer_masked () + tmo;

        do {
                ulong now = get_timer_masked ();
                diff = endtime - now;
        } while (diff >= 0);
}

/*
 * This function is derived from PowerPC code (read timebase as long long).
 * On ARM it just returns the timer value.
 */
unsigned long long get_ticks(void)
{
        return get_timer(0);
}

/*
 * This function is derived from PowerPC code (timebase clock frequency).
 * On ARM it returns the number of timer ticks per second.
 */
ulong get_tbclk (void)
{
        ulong tbclk;

        tbclk = CONFIG_SYS_HZ;
        return tbclk;
}