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3eb90bad65
According to the PPC reference implementation the udelay() function is responsible for resetting the watchdog timer as frequently as needed. Most other architectures do not meet that requirement, so long-running operations might result in a watchdog reset. This patch adds a generic udelay() function which takes care of resetting the watchdog before calling an architecture-specific __udelay(). Signed-off-by: Ingo van Lil <inguin@gmx.de>
71 lines
2.1 KiB
C
71 lines
2.1 KiB
C
/*
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* (C) Copyright 2009 Alessandro Rubini
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#include <common.h>
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#include <asm/io.h>
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#include <asm/arch/mtu.h>
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/*
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* The timer is a decrementer, we'll left it free running at 2.4MHz.
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* We have 2.4 ticks per microsecond and an overflow in almost 30min
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*/
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#define TIMER_CLOCK (24 * 100 * 1000)
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#define COUNT_TO_USEC(x) ((x) * 5 / 12) /* overflows at 6min */
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#define USEC_TO_COUNT(x) ((x) * 12 / 5) /* overflows at 6min */
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#define TICKS_PER_HZ (TIMER_CLOCK / CONFIG_SYS_HZ)
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#define TICKS_TO_HZ(x) ((x) / TICKS_PER_HZ)
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/* macro to read the 32 bit timer: since it decrements, we invert read value */
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#define READ_TIMER() (~readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0)))
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/* Configure a free-running, auto-wrap counter with no prescaler */
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int timer_init(void)
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{
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writel(MTU_CRn_ENA | MTU_CRn_PRESCALE_1 | MTU_CRn_32BITS,
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CONFIG_SYS_TIMERBASE + MTU_CR(0));
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reset_timer();
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return 0;
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}
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/* Restart counting from 0 */
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void reset_timer(void)
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{
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writel(0, CONFIG_SYS_TIMERBASE + MTU_LR(0)); /* Immediate effect */
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}
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/* Return how many HZ passed since "base" */
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ulong get_timer(ulong base)
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{
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return TICKS_TO_HZ(READ_TIMER()) - base;
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}
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/* Delay x useconds */
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void __udelay(unsigned long usec)
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{
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ulong ini, end;
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ini = READ_TIMER();
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end = ini + USEC_TO_COUNT(usec);
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while ((signed)(end - READ_TIMER()) > 0)
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;
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}
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