timer.c
3.21 KB
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/*
* (C) Copyright 2007-2008
* Stelian Pop <stelian.pop@leadtechdesign.com>
* Lead Tech Design <www.leadtechdesign.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/arch/hardware.h>
#include <asm/arch/at91_pit.h>
#include <asm/arch/at91_pmc.h>
#include <asm/arch/clk.h>
#include <asm/arch/io.h>
#include <div64.h>
/*
* We're using the AT91CAP9/SAM9 PITC in 32 bit mode, by
* setting the 20 bit counter period to its maximum (0xfffff).
*/
#define TIMER_LOAD_VAL 0xfffff
#define READ_RESET_TIMER at91_sys_read(AT91_PIT_PIVR)
#define READ_TIMER at91_sys_read(AT91_PIT_PIIR)
static ulong timestamp;
static ulong lastinc;
static ulong timer_freq;
static inline unsigned long long tick_to_time(unsigned long long tick)
{
tick *= CONFIG_SYS_HZ;
do_div(tick, timer_freq);
return tick;
}
static inline unsigned long long usec_to_tick(unsigned long long usec)
{
usec *= timer_freq;
do_div(usec, 1000000);
return usec;
}
/* nothing really to do with interrupts, just starts up a counter. */
int timer_init(void)
{
/*
* Enable PITC Clock
* The clock is already enabled for system controller in boot
*/
at91_sys_write(AT91_PMC_PCER, 1 << AT91_ID_SYS);
/* Enable PITC */
at91_sys_write(AT91_PIT_MR, TIMER_LOAD_VAL | AT91_PIT_PITEN);
reset_timer_masked();
timer_freq = get_mck_clk_rate() >> 4;
return 0;
}
/*
* timer without interrupts
*/
unsigned long long get_ticks(void)
{
ulong now = READ_TIMER;
if (now >= lastinc) /* normal mode (non roll) */
/* move stamp forward with absolut diff ticks */
timestamp += (now - lastinc);
else /* we have rollover of incrementer */
timestamp += (0xFFFFFFFF - lastinc) + now;
lastinc = now;
return timestamp;
}
void reset_timer_masked(void)
{
/* reset time */
lastinc = READ_TIMER; /* capture current incrementer value time */
timestamp = 0; /* start "advancing" time stamp from 0 */
}
ulong get_timer_masked(void)
{
return tick_to_time(get_ticks());
}
void __udelay(unsigned long usec)
{
unsigned long long tmp;
ulong tmo;
tmo = usec_to_tick(usec);
tmp = get_ticks() + tmo; /* get current timestamp */
while (get_ticks() < tmp) /* loop till event */
/*NOP*/;
}
void reset_timer(void)
{
reset_timer_masked();
}
ulong get_timer(ulong base)
{
return get_timer_masked () - base;
}
/*
* 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)
{
ulong tbclk;
tbclk = CONFIG_SYS_HZ;
return tbclk;
}