timer.c

/*
 * Copyright (C) 2012 Michal Simek <monstr@monstr.eu>
 * Copyright (C) 2011-2012 Xilinx, Inc. All rights reserved.
 *
 * (C) Copyright 2008
 * Guennadi Liakhovetki, DENX Software Engineering, <lg@denx.de>
 *
 * (C) Copyright 2004
 * Philippe Robin, ARM Ltd. <philippe.robin@arm.com>
 *
 * (C) Copyright 2002-2004
 * Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
 *
 * (C) Copyright 2003
 * Texas Instruments <www.ti.com>
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Marius Groeger <mgroeger@sysgo.de>
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Alex Zuepke <azu@sysgo.de>
 *
 * 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 <div64.h>
#include <asm/io.h>
#include <asm/arch/hardware.h>

DECLARE_GLOBAL_DATA_PTR;

struct scu_timer {
	u32 load; /* Timer Load Register */
	u32 counter; /* Timer Counter Register */
	u32 control; /* Timer Control Register */
};

static struct scu_timer *timer_base =
			      (struct scu_timer *)ZYNQ_SCUTIMER_BASEADDR;

#define SCUTIMER_CONTROL_PRESCALER_MASK	0x0000FF00 /* Prescaler */
#define SCUTIMER_CONTROL_PRESCALER_SHIFT	8
#define SCUTIMER_CONTROL_AUTO_RELOAD_MASK	0x00000002 /* Auto-reload */
#define SCUTIMER_CONTROL_ENABLE_MASK		0x00000001 /* Timer enable */

#define TIMER_LOAD_VAL 0xFFFFFFFF
#define TIMER_PRESCALE 255
#define TIMER_TICK_HZ  (CONFIG_CPU_FREQ_HZ / 2 / TIMER_PRESCALE)

int timer_init(void)
{
	const u32 emask = SCUTIMER_CONTROL_AUTO_RELOAD_MASK |
			(TIMER_PRESCALE << SCUTIMER_CONTROL_PRESCALER_SHIFT) |
			SCUTIMER_CONTROL_ENABLE_MASK;

	/* Load the timer counter register */
	writel(0xFFFFFFFF, &timer_base->counter);

	/*
	 * Start the A9Timer device
	 * Enable Auto reload mode, Clear prescaler control bits
	 * Set prescaler value, Enable the decrementer
	 */
	clrsetbits_le32(&timer_base->control, SCUTIMER_CONTROL_PRESCALER_MASK,
								emask);

	/* Reset time */
	gd->arch.lastinc = readl(&timer_base->counter) /
					(TIMER_TICK_HZ / CONFIG_SYS_HZ);
	gd->arch.tbl = 0;

	return 0;
}

/*
 * This function is derived from PowerPC code (read timebase as long long).
 * On ARM it just returns the timer value.
 */
ulong get_timer_masked(void)
{
	ulong now;

	now = readl(&timer_base->counter) / (TIMER_TICK_HZ / CONFIG_SYS_HZ);

	if (gd->arch.lastinc >= now) {
		/* Normal mode */
		gd->arch.tbl += gd->arch.lastinc - now;
	} else {
		/* We have an overflow ... */
		gd->arch.tbl += gd->arch.lastinc + TIMER_LOAD_VAL - now;
	}
	gd->arch.lastinc = now;

	return gd->arch.tbl;
}

void __udelay(unsigned long usec)
{
	u32 countticks;
	u32 timeend;
	u32 timediff;
	u32 timenow;

	if (usec == 0)
		return;

	countticks = (u32) (((unsigned long long) TIMER_TICK_HZ * usec) /
								1000000);

	/* decrementing timer */
	timeend = readl(&timer_base->counter) - countticks;

#if TIMER_LOAD_VAL != 0xFFFFFFFF
	/* do not manage multiple overflow */
	if (countticks >= TIMER_LOAD_VAL)
		countticks = TIMER_LOAD_VAL - 1;
#endif

	do {
		timenow = readl(&timer_base->counter);

		if (timenow >= timeend) {
			/* normal case */
			timediff = timenow - timeend;
		} else {
			if ((TIMER_LOAD_VAL - timeend + timenow) <=
								countticks) {
				/* overflow */
				timediff = TIMER_LOAD_VAL - timeend + timenow;
			} else {
				/* missed the exact match */
				break;
			}
		}
	} while (timediff > 0);
}

/* Timer without interrupts */
ulong get_timer(ulong base)
{
	return get_timer_masked() - base;
}

/*
 * This function is derived from PowerPC code (read timebase as long long).
 * On ARM it just returns the timer value.
 */
unsigned long long get_ticks(void)
{
	return get_timer(0);
}

/*
 * 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)
{
	return CONFIG_SYS_HZ;
}