u-boot-brain/cpu/s3c44b0/timer.c
Ingo van Lil 3eb90bad65 Generic udelay() with watchdog support
According to the PPC reference implementation the udelay() function is
responsible for resetting the watchdog timer as frequently as needed.
Most other architectures do not meet that requirement, so long-running
operations might result in a watchdog reset.

This patch adds a generic udelay() function which takes care of
resetting the watchdog before calling an architecture-specific
__udelay().

Signed-off-by: Ingo van Lil <inguin@gmx.de>
2009-12-05 01:08:53 +01:00

137 lines
2.5 KiB
C

/*
* (C) Copyright 2004
* DAVE Srl
* http://www.dave-tech.it
* http://www.wawnet.biz
* mailto:info@wawnet.biz
*
* 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/hardware.h>
/* we always count down the max. */
#define TIMER_LOAD_VAL 0xffff
/* macro to read the 16 bit timer */
#define READ_TIMER (TCNTO1 & 0xffff)
#ifdef CONFIG_USE_IRQ
#error CONFIG_USE_IRQ NOT supported
#endif
static ulong timestamp;
static ulong lastdec;
int timer_init (void)
{
TCFG0 = 0x000000E9;
TCFG1 = 0x00000004;
TCON = 0x00000900;
TCNTB1 = TIMER_LOAD_VAL;
TCMPB1 = 0;
TCON = 0x00000B00;
TCON = 0x00000900;
lastdec = TCNTB1 = TIMER_LOAD_VAL;
timestamp = 0;
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;
}
void __udelay (unsigned long usec)
{
ulong tmo;
tmo = usec / 1000;
tmo *= CONFIG_SYS_HZ;
tmo /= 8;
tmo += get_timer (0);
while (get_timer_masked () < tmo)
/*NOP*/;
}
void reset_timer_masked (void)
{
/* reset time */
lastdec = READ_TIMER;
timestamp = 0;
}
ulong get_timer_masked (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;
}
void udelay_masked (unsigned long usec)
{
ulong tmo;
ulong endtime;
signed long diff;
if (usec >= 1000) {
tmo = usec / 1000;
tmo *= CONFIG_SYS_HZ;
tmo /= 8;
} else {
tmo = usec * CONFIG_SYS_HZ;
tmo /= (1000*8);
}
endtime = get_timer(0) + tmo;
do {
ulong now = get_timer_masked ();
diff = endtime - now;
} while (diff >= 0);
}