u-boot/cpu/arm926ejs/nomadik/timer.c
Alessandro Rubini 095a460b49 arm nomadik: use 1000 as HZ value and rewrite timer code
This sets CONFIG_SYS_HZ to 1000 as required, and completely rewrites
timer code, which is now both correct and much smaller.  Unused
functions like udelay_masked() have been removed as no driver uses
them, even the ones that are not currently active for this board.
mtu.h is copied literally from the kernel sources.

Signed-off-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
2009-07-06 21:53:08 +02:00

70 lines
2.1 KiB
C

/*
* (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 32 bit timer: since it decrements, we invert read value */
#define READ_TIMER() (~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)
{
writel(0, CONFIG_SYS_TIMERBASE + MTU_LR(0)); /* Immediate effect */
}
/* 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)
;
}