u-boot/cpu/arm925t/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
3.4 KiB
C

/*
* (C) Copyright 2009
* 2N Telekomunikace, <www.2n.cz>
*
* (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
* Gary Jennejohn, DENX Software Engineering, <garyj@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 <arm925t.h>
#include <configs/omap1510.h>
#include <asm/io.h>
#define TIMER_LOAD_VAL 0xffffffff
#define TIMER_CLOCK (CONFIG_SYS_CLK_FREQ / (2 << CONFIG_SYS_PTV))
static uint32_t timestamp;
static uint32_t lastdec;
/* nothing really to do with interrupts, just starts up a counter. */
int timer_init (void)
{
/* Start the decrementer ticking down from 0xffffffff */
__raw_writel(TIMER_LOAD_VAL, CONFIG_SYS_TIMERBASE + LOAD_TIM);
__raw_writel(MPUTIM_ST | MPUTIM_AR | MPUTIM_CLOCK_ENABLE |
(CONFIG_SYS_PTV << MPUTIM_PTV_BIT),
CONFIG_SYS_TIMERBASE + CNTL_TIMER);
/* 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 preserve advance timestamp value */
void __udelay (unsigned long usec)
{
int32_t tmo = usec * (TIMER_CLOCK / 1000) / 1000;
uint32_t now, last = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM);
while (tmo > 0) {
now = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM);
if (last < now) /* count down timer underflow */
tmo -= TIMER_LOAD_VAL - now + last;
else
tmo -= last - now;
last = now;
}
}
void reset_timer_masked (void)
{
/* reset time */
lastdec = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM) /
(TIMER_CLOCK / CONFIG_SYS_HZ);
timestamp = 0; /* start "advancing" time stamp from 0 */
}
ulong get_timer_masked (void)
{
uint32_t now = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM) /
(TIMER_CLOCK / CONFIG_SYS_HZ);
if (lastdec < now) /* count down timer underflow */
timestamp += TIMER_LOAD_VAL / (TIMER_CLOCK / CONFIG_SYS_HZ) -
now + lastdec;
else
timestamp += lastdec - 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.
*/
ulong get_tbclk (void)
{
return CONFIG_SYS_HZ;
}