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/*
* (C) Copyright 2009 Alessandro Rubini
*
* 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/io.h>
#include <asm/arch/mtu.h>
/*
* The timer is a decrementer, we'll left it free running at 2.4MHz.
* We have 2.4 ticks per microsecond and an overflow in almost 30min
*/
#define TIMER_CLOCK (24 * 100 * 1000)
#define COUNT_TO_USEC(x) ((x) * 5 / 12) /* overflows at 6min */
#define USEC_TO_COUNT(x) ((x) * 12 / 5) /* overflows at 6min */
#define TICKS_PER_HZ (TIMER_CLOCK / CONFIG_SYS_HZ)
#define TICKS_TO_HZ(x) ((x) / TICKS_PER_HZ)
/* macro to read the decrementing 32 bit timer as an increasing count */
#define READ_TIMER() (0 - readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0)))
/* Configure a free-running, auto-wrap counter with no prescaler */
int timer_init(void)
{
writel(MTU_CRn_ENA | MTU_CRn_PRESCALE_1 | MTU_CRn_32BITS,
CONFIG_SYS_TIMERBASE + MTU_CR(0));
reset_timer();
return 0;
}
/* Restart counting from 0 */
void reset_timer(void)
{
ulong val;
writel(0, CONFIG_SYS_TIMERBASE + MTU_LR(0));
/*
* The load-register isn't really immediate: it changes on clock
* edges, so we must wait for our newly-written value to appear.
* Since we might miss reading 0, wait for any change in value.
*/
val = READ_TIMER();
while (READ_TIMER() == val)
;
}
/* Return how many HZ passed since "base" */
ulong get_timer(ulong base)
{
return TICKS_TO_HZ(READ_TIMER()) - base;
}
/* Delay x useconds */
void __udelay(unsigned long usec)
{
ulong ini, end;
ini = READ_TIMER();
end = ini + USEC_TO_COUNT(usec);
while ((signed)(end - READ_TIMER()) > 0)
;
}
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