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/*
* (C) Copyright 2011, Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
* (C) Copyright 2011, Julius Baxter <julius@opencores.org>
* (C) Copyright 2003
* Wolfgang Denk, DENX Software Engineering, wd@denx.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 <asm/system.h>
#include <asm/openrisc_exc.h>
static ulong timestamp;
/* how many counter cycles in a jiffy */
#define TIMER_COUNTER_CYCLES (CONFIG_SYS_CLK_FREQ/CONFIG_SYS_OPENRISC_TMR_HZ)
/* how many ms elapses between each timer interrupt */
#define TIMER_TIMESTAMP_INC (1000/CONFIG_SYS_OPENRISC_TMR_HZ)
/* how many cycles per ms */
#define TIMER_CYCLES_MS (CONFIG_SYS_CLK_FREQ/1000)
/* how many cycles per us */
#define TIMER_CYCLES_US (CONFIG_SYS_CLK_FREQ/1000000uL)
void timer_isr(void)
{
timestamp += TIMER_TIMESTAMP_INC;
mtspr(SPR_TTMR, SPR_TTMR_IE | SPR_TTMR_RT |
(TIMER_COUNTER_CYCLES & SPR_TTMR_TP));
}
int timer_init(void)
{
/* Install timer exception handler */
exception_install_handler(EXC_TIMER, timer_isr);
/* Set up the timer for the first expiration. */
timestamp = 0;
mtspr(SPR_TTMR, SPR_TTMR_IE | SPR_TTMR_RT |
(TIMER_COUNTER_CYCLES & SPR_TTMR_TP));
/* Enable tick timer exception in supervisor register */
mtspr(SPR_SR, mfspr(SPR_SR) | SPR_SR_TEE);
return 0;
}
void reset_timer(void)
{
timestamp = 0;
mtspr(SPR_TTMR, SPR_TTMR_IE | SPR_TTMR_RT |
(TIMER_COUNTER_CYCLES & SPR_TTMR_TP));
}
/*
* The timer value in ms is calculated by taking the
* value accumulated by full timer revolutions plus the value
* accumulated in this period
*/
ulong get_timer(ulong base)
{
return timestamp + mfspr(SPR_TTCR)/TIMER_CYCLES_MS - base;
}
void set_timer(ulong t)
{
reset_timer();
timestamp = t;
}
void __udelay(ulong usec)
{
ulong elapsed = 0;
ulong tick;
ulong last_tick;
last_tick = mfspr(SPR_TTCR);
while ((elapsed / TIMER_CYCLES_US) < usec) {
tick = mfspr(SPR_TTCR);
if (tick >= last_tick)
elapsed += (tick - last_tick);
else
elapsed += TIMER_COUNTER_CYCLES - (last_tick - tick);
last_tick = tick;
}
}
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