/*
 * (C) Copyright 2009 Faraday Technology
 * Po-Yu Chuang <ratbert@faraday-tech.com>
 *
 * Copyright (C) 2011 Andes Technology Corporation
 * Shawn Lin, Andes Technology Corporation <nobuhiro@andestech.com>
 * Macpaul Lin, Andes Technology Corporation <macpaul@andestech.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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <common.h>
#include <asm/io.h>
#include <faraday/fttmr010.h>

static ulong timestamp;
static ulong lastdec;

int timer_init(void)
{
        struct fttmr010 *tmr = (struct fttmr010 *)CONFIG_FTTMR010_BASE;
        unsigned int cr;

        debug("%s()\n", __func__);

        /* disable timers */
        writel(0, &tmr->cr);

#ifdef CONFIG_FTTMR010_EXT_CLK
        /* use 32768Hz oscillator for RTC, WDT, TIMER */
        ftpmu010_32768osc_enable();
#endif

        /* setup timer */
        writel(TIMER_LOAD_VAL, &tmr->timer3_load);
        writel(TIMER_LOAD_VAL, &tmr->timer3_counter);
        writel(0, &tmr->timer3_match1);
        writel(0, &tmr->timer3_match2);

        /* we don't want timer to issue interrupts */
        writel(FTTMR010_TM3_MATCH1 |
               FTTMR010_TM3_MATCH2 |
               FTTMR010_TM3_OVERFLOW,
               &tmr->interrupt_mask);

        cr = readl(&tmr->cr);
#ifdef CONFIG_FTTMR010_EXT_CLK
        cr |= FTTMR010_TM3_CLOCK;       /* use external clock */
#endif
        cr |= FTTMR010_TM3_ENABLE;
        writel(cr, &tmr->cr);

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

        return 0;
}

/*
 * timer without interrupts
 */

/*
 * reset time
 */
void reset_timer_masked(void)
{
        struct fttmr010 *tmr = (struct fttmr010 *)CONFIG_FTTMR010_BASE;

        /* capure current decrementer value time */
#ifdef CONFIG_FTTMR010_EXT_CLK
        lastdec = readl(&tmr->timer3_counter) / (TIMER_CLOCK / CONFIG_SYS_HZ);
#else
        lastdec = readl(&tmr->timer3_counter) / (CONFIG_SYS_CLK_FREQ / 2);
#endif
        timestamp = 0;          /* start "advancing" time stamp from 0 */

        debug("%s(): lastdec = %lx\n", __func__, lastdec);
}

void reset_timer(void)
{
        debug("%s()\n", __func__);
        reset_timer_masked();
}

/*
 * return timer ticks
 */
ulong get_timer_masked(void)
{
        struct fttmr010 *tmr = (struct fttmr010 *)CONFIG_FTTMR010_BASE;

        /* current tick value */
#ifdef CONFIG_FTTMR010_EXT_CLK
        ulong now = readl(&tmr->timer3_counter) / (TIMER_CLOCK / CONFIG_SYS_HZ);
#else
        ulong now = readl(&tmr->timer3_counter) / \
                        (CONFIG_SYS_CLK_FREQ / 2 / 1024);
#endif

        debug("%s(): now = %lx, lastdec = %lx\n", __func__, now, lastdec);

        if (lastdec >= now) {
                /*
                 * normal mode (non roll)
                 * move stamp fordward with absoulte diff ticks
                 */
                timestamp += lastdec - now;
        } 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;

        debug("%s() returns %lx\n", __func__, timestamp);

        return timestamp;
}

/*
 * return difference between timer ticks and base
 */
ulong get_timer(ulong base)
{
        debug("%s(%lx)\n", __func__, base);
        return get_timer_masked() - base;
}

void set_timer(ulong t)
{
        debug("%s(%lx)\n", __func__, t);
        timestamp = t;
}

/* delay x useconds AND preserve advance timestamp value */
void __udelay(unsigned long usec)
{
        struct fttmr010 *tmr = (struct fttmr010 *)CONFIG_FTTMR010_BASE;

#ifdef CONFIG_FTTMR010_EXT_CLK
        long tmo = usec * (TIMER_CLOCK / 1000) / 1000;
#else
        long tmo = usec * ((CONFIG_SYS_CLK_FREQ / 2) / 1000) / 1000;
#endif
        unsigned long now, last = readl(&tmr->timer3_counter);

        debug("%s(%lu)\n", __func__, usec);
        while (tmo > 0) {
                now = readl(&tmr->timer3_counter);
                if (now > last) /* count down timer overflow */
                        tmo -= TIMER_LOAD_VAL + last - now;
                else
                        tmo -= last - now;
                last = now;
        }
}

/*
 * 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)
{
        debug("%s()\n", __func__);
        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)
{
        debug("%s()\n", __func__);
#ifdef CONFIG_FTTMR010_EXT_CLK
        return CONFIG_SYS_HZ;
#else
        return CONFIG_SYS_CLK_FREQ;
#endif
}