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/*
* Cirrus Logic EP93xx timer support.
*
* Copyright (C) 2009, 2010 Matthias Kaehlcke <matthias@kaehlcke.net>
*
* Copyright (C) 2004, 2005
* Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com>
*
* Based on the original intr.c Cirrus Logic EP93xx Rev D. interrupt support,
* author unknown.
*
* 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.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <common.h>
#include <linux/types.h>
#include <asm/arch/ep93xx.h>
#include <asm/io.h>
#include <div64.h>
#define TIMER_CLKSEL (1 << 3)
#define TIMER_ENABLE (1 << 7)
#define TIMER_FREQ 508469 /* ticks / second */
#define TIMER_MAX_VAL 0xFFFFFFFF
static struct ep93xx_timer
{
unsigned long long ticks;
unsigned long last_read;
} timer;
static inline unsigned long long usecs_to_ticks(unsigned long usecs)
{
unsigned long long ticks = (unsigned long long)usecs * TIMER_FREQ;
do_div(ticks, 1000 * 1000);
return ticks;
}
static inline void read_timer(void)
{
struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
const unsigned long now = TIMER_MAX_VAL - readl(&timer_regs->timer3.value);
if (now >= timer.last_read)
timer.ticks += now - timer.last_read;
else
/* an overflow occurred */
timer.ticks += TIMER_MAX_VAL - timer.last_read + now;
timer.last_read = now;
}
/*
* Get the number of ticks (in CONFIG_SYS_HZ resolution)
*/
unsigned long long get_ticks(void)
{
unsigned long long sys_ticks;
read_timer();
sys_ticks = timer.ticks * CONFIG_SYS_HZ;
do_div(sys_ticks, TIMER_FREQ);
return sys_ticks;
}
unsigned long get_timer_masked(void)
{
return get_ticks();
}
unsigned long get_timer(unsigned long base)
{
return get_timer_masked() - base;
}
void reset_timer_masked(void)
{
read_timer();
timer.ticks = 0;
}
void reset_timer(void)
{
reset_timer_masked();
}
void __udelay(unsigned long usec)
{
unsigned long long target;
read_timer();
target = timer.ticks + usecs_to_ticks(usec);
while (timer.ticks < target)
read_timer();
}
int timer_init(void)
{
struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
/* use timer 3 with 508KHz and free running, not enabled now */
writel(TIMER_CLKSEL, &timer_regs->timer3.control);
/* set initial timer value */
writel(TIMER_MAX_VAL, &timer_regs->timer3.load);
/* Enable the timer */
writel(TIMER_ENABLE | TIMER_CLKSEL,
&timer_regs->timer3.control);
reset_timer_masked();
return 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;
}
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