/*
 * Copyright (C) 2009 Samsung Electronics
 * Heungjun Kim <riverful.kim@samsung.com>
 * Inki Dae <inki.dae@samsung.com>
 * Minkyu Kang <mk7.kang@samsung.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 <asm/io.h>
#include <asm/arch/pwm.h>
#include <asm/arch/clk.h>

#define PRESCALER_1             (16 - 1)        /* prescaler of timer 2, 3, 4 */
#define MUX_DIV_2               1               /* 1/2 period */
#define MUX_DIV_4               2               /* 1/4 period */
#define MUX_DIV_8               3               /* 1/8 period */
#define MUX_DIV_16              4               /* 1/16 period */
#define MUX4_DIV_SHIFT          16

#define TCON_TIMER4_SHIFT       20

static unsigned long count_value;

/* Internal tick units */
static unsigned long long timestamp;    /* Monotonic incrementing timer */
static unsigned long lastdec;           /* Last decremneter snapshot */

/* macro to read the 16 bit timer */
static inline struct s5pc1xx_timer *s5pc1xx_get_base_timer(void)
{
        if (cpu_is_s5pc110())
                return (struct s5pc1xx_timer *)S5PC110_TIMER_BASE;
        else
                return (struct s5pc1xx_timer *)S5PC100_TIMER_BASE;
}

int timer_init(void)
{
        struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();
        u32 val;

        /*
         * @ PWM Timer 4
         * Timer Freq(HZ) =
         *      PCLK / { (prescaler_value + 1) * (divider_value) }
         */

        /* set prescaler : 16 */
        /* set divider : 2 */
        writel((PRESCALER_1 & 0xff) << 8, &timer->tcfg0);
        writel((MUX_DIV_2 & 0xf) << MUX4_DIV_SHIFT, &timer->tcfg1);

        if (count_value == 0) {
                /* reset initial value */
                /* count_value = 2085937.5(HZ) (per 1 sec)*/
                count_value = get_pclk() / ((PRESCALER_1 + 1) *
                                (MUX_DIV_2 + 1));

                /* count_value / 100 = 20859.375(HZ) (per 10 msec) */
                count_value = count_value / 100;
        }

        /* set count value */
        writel(count_value, &timer->tcntb4);
        lastdec = count_value;

        val = (readl(&timer->tcon) & ~(0x07 << TCON_TIMER4_SHIFT)) |
                S5PC1XX_TCON4_AUTO_RELOAD;

        /* auto reload & manual update */
        writel(val | S5PC1XX_TCON4_UPDATE, &timer->tcon);

        /* start PWM timer 4 */
        writel(val | S5PC1XX_TCON4_START, &timer->tcon);

        timestamp = 0;

        return 0;
}

/*
 * timer without interrupts
 */
void reset_timer(void)
{
        reset_timer_masked();
}

unsigned long get_timer(unsigned long base)
{
        return get_timer_masked() - base;
}

void set_timer(unsigned long t)
{
        timestamp = t;
}

/* delay x useconds */
void __udelay(unsigned long usec)
{
        unsigned long tmo, tmp;

        if (usec >= 1000) {
                /*
                 * if "big" number, spread normalization
                 * to seconds
                 * 1. start to normalize for usec to ticks per sec
                 * 2. find number of "ticks" to wait to achieve target
                 * 3. finish normalize.
                 */
                tmo = usec / 1000;
                tmo *= (CONFIG_SYS_HZ * count_value / 10);
                tmo /= 1000;
        } else {
                /* else small number, don't kill it prior to HZ multiply */
                tmo = usec * CONFIG_SYS_HZ * count_value / 10;
                tmo /= (1000 * 1000);
        }

        /* get current timestamp */
        tmp = get_timer(0);

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

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

void reset_timer_masked(void)
{
        struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();

        /* reset time */
        lastdec = readl(&timer->tcnto4);
        timestamp = 0;
}

unsigned long get_timer_masked(void)
{
        struct s5pc1xx_timer *const timer = s5pc1xx_get_base_timer();
        unsigned long now = readl(&timer->tcnto4);

        if (lastdec >= now)
                timestamp += lastdec - now;
        else
                timestamp += lastdec + count_value - now;

        lastdec = now;

        return timestamp;
}

/*
 * 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.
 */
unsigned long get_tbclk(void)
{
        return CONFIG_SYS_HZ;
}