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/*
* (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>
*
* (C) Copyright 2008
* Guennadi Liakhovetki, DENX Software Engineering, <lg@denx.de>
*
* 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/proc-armv/ptrace.h>
#include <asm/arch/s3c6400.h>
#include <div64.h>
static ulong timer_load_val;
#define PRESCALER 167
static s3c64xx_timers *s3c64xx_get_base_timers(void)
{
return (s3c64xx_timers *)ELFIN_TIMER_BASE;
}
/* macro to read the 16 bit timer */
static inline ulong read_timer(void)
{
s3c64xx_timers *const timers = s3c64xx_get_base_timers();
return timers->TCNTO4;
}
/* Internal tick units */
/* Last decremneter snapshot */
static unsigned long lastdec;
/* Monotonic incrementing timer */
static unsigned long long timestamp;
int timer_init(void)
{
s3c64xx_timers *const timers = s3c64xx_get_base_timers();
/* use PWM Timer 4 because it has no output */
/*
* We use the following scheme for the timer:
* Prescaler is hard fixed at 167, divider at 1/4.
* This gives at PCLK frequency 66MHz approx. 10us ticks
* The timer is set to wrap after 100s, at 66MHz this obviously
* happens after 10,000,000 ticks. A long variable can thus
* keep values up to 40,000s, i.e., 11 hours. This should be
* enough for most uses:-) Possible optimizations: select a
* binary-friendly frequency, e.g., 1ms / 128. Also calculate
* the prescaler automatically for other PCLK frequencies.
*/
timers->TCFG0 = PRESCALER << 8;
if (timer_load_val == 0) {
timer_load_val = get_PCLK() / PRESCALER * (100 / 4); /* 100s */
timers->TCFG1 = (timers->TCFG1 & ~0xf0000) | 0x20000;
}
/* load value for 10 ms timeout */
lastdec = timers->TCNTB4 = timer_load_val;
/* auto load, manual update of Timer 4 */
timers->TCON = (timers->TCON & ~0x00700000) | TCON_4_AUTO |
TCON_4_UPDATE;
/* auto load, start Timer 4 */
timers->TCON = (timers->TCON & ~0x00700000) | TCON_4_AUTO | COUNT_4_ON;
timestamp = 0;
return 0;
}
/*
* timer without interrupts
*/
/*
* 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)
{
ulong now = read_timer();
if (lastdec >= now) {
/* normal mode */
timestamp += lastdec - now;
} else {
/* we have an overflow ... */
timestamp += lastdec + timer_load_val - now;
}
lastdec = now;
return timestamp;
}
/*
* 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)
{
/* We overrun in 100s */
return (ulong)(timer_load_val / 100);
}
ulong get_timer_masked(void)
{
unsigned long long res = get_ticks();
do_div (res, (timer_load_val / (100 * CONFIG_SYS_HZ)));
return res;
}
ulong get_timer(ulong base)
{
return get_timer_masked() - base;
}
void __udelay(unsigned long usec)
{
unsigned long long tmp;
ulong tmo;
tmo = (usec + 9) / 10;
tmp = get_ticks() + tmo; /* get current timestamp */
while (get_ticks() < tmp)/* loop till event */
/*NOP*/;
}
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