u-boot/arch/arm/cpu/armv7/socfpga/timer.c

/*
 *  Copyright (C) 2012 Altera Corporation <www.altera.com>
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <common.h>
#include <asm/io.h>
#include <asm/arch/timer.h>

DECLARE_GLOBAL_DATA_PTR;

static const struct socfpga_timer *timer_base = (void *)CONFIG_SYS_TIMERBASE;

/*
 * Timer initialization
 */
int timer_init(void)
{
	writel(TIMER_LOAD_VAL, &timer_base->load_val);
	writel(TIMER_LOAD_VAL, &timer_base->curr_val);
	writel(readl(&timer_base->ctrl) | 0x3, &timer_base->ctrl);
	return 0;
}

static u32 read_timer(void)
{
	return readl(&timer_base->curr_val);
}

/*
 * Delay x useconds
 */
void __udelay(unsigned long usec)
{
	unsigned long now, last;
	/*
	 * get the tmo value based on timer clock speed
	 * tmo = delay required / period of timer clock
	 */
	long tmo = usec * CONFIG_TIMER_CLOCK_KHZ / 1000;

	last = read_timer();
	while (tmo > 0) {
		now = read_timer();
		if (last >= now)
			/* normal mode (non roll) */
			tmo -= last - now;
		else
			/* we have overflow of the count down timer */
			tmo -= TIMER_LOAD_VAL - last + now;
		last = now;
	}
}

/*
 * Get the timer value
 */
ulong get_timer(ulong base)
{
	return get_timer_masked() - base;
}

/*
 * Timer : get the time difference
 * Unit of tick is based on the CONFIG_SYS_HZ
 */
ulong get_timer_masked(void)
{
	/* current tick value */
	ulong now = read_timer() / (CONFIG_TIMER_CLOCK_KHZ/CONFIG_SYS_HZ);
	if (gd->arch.lastinc >= now) {
		/* normal mode (non roll) */
		/* move stamp forward with absolute diff ticks */
		gd->arch.tbl += gd->arch.lastinc - now;
	} else {
		/* we have overflow of the count down timer */
		gd->arch.tbl += TIMER_LOAD_VAL - gd->arch.lastinc + now;
	}
	gd->arch.lastinc = now;
	return gd->arch.tbl;
}

/*
 * Reset the timer
 */
void reset_timer(void)
{
	/* capture current decrementer value time */
	gd->arch.lastinc = read_timer() /
				(CONFIG_TIMER_CLOCK_KHZ / CONFIG_SYS_HZ);
	/* start "advancing" time stamp from 0 */
	gd->arch.tbl = 0;
}