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phoenix |
/*
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* linux/include/asm-arm/arch-at91rm9200/time.h
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*
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* Copyright (C) 2003 SAN People
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* Copyright (C) 2003 ATMEL
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (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, MA 02111-1307 USA
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*/
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#ifndef __ASM_ARCH_TIME_H
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#define __ASM_ARCH_TIME_H
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#include <asm/system.h>
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extern unsigned long (*gettimeoffset)(void);
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/*
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* Returns number of microseconds since last timer interrupt. Note that interrupts
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* will have been disabled by do_gettimeofday()
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* 'LATCH' is hwclock ticks (see CLOCK_TICK_RATE in timex.h) per jiffy.
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* 'tick' is usecs per jiffy (linux/timex.h).
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*/
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static unsigned long at91rm9200_gettimeoffset(void)
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{
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unsigned long elapsed;
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elapsed = (AT91_SYS->ST_CRTR - AT91_SYS->ST_RTAR) & AT91C_ST_ALMV;
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return (unsigned long)(elapsed * tick) / LATCH;
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}
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/*
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* IRQ handler for the timer.
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*/
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static void at91rm9200_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
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{
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if (AT91_SYS->ST_SR & AT91C_ST_PITS) { /* This is a shared interrupt */
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do {
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do_timer(regs);
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AT91_SYS->ST_RTAR = (AT91_SYS->ST_RTAR + LATCH) & AT91C_ST_ALMV;
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} while (((AT91_SYS->ST_CRTR - AT91_SYS->ST_RTAR) & AT91C_ST_ALMV) >= LATCH);
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do_profile(regs);
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}
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}
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/*
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* Set up timer interrupt.
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*/
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static inline void setup_timer(void)
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{
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/* Disable all timer interrupts */
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AT91_SYS->ST_IDR = AT91C_ST_PITS | AT91C_ST_WDOVF | AT91C_ST_RTTINC | AT91C_ST_ALMS;
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(void) AT91_SYS->ST_SR; /* Clear any pending interrupts */
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/*
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* Make IRQs happen for the system timer.
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*/
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timer_irq.handler = at91rm9200_timer_interrupt;
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timer_irq.flags = SA_SHIRQ | SA_INTERRUPT;
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setup_arm_irq(AT91C_ID_SYS, &timer_irq);
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gettimeoffset = at91rm9200_gettimeoffset;
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/* Set initial alarm to 0 */
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AT91_SYS->ST_RTAR = 0;
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/* Real time counter incremented every 30.51758 microseconds */
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AT91_SYS->ST_RTMR = 1;
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/* Set Period Interval timer */
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AT91_SYS->ST_PIMR = LATCH;
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/* Change the kernel's 'tick' value to 10009 usec. (the default is 10000) */
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tick = (LATCH * 1000000) / CLOCK_TICK_RATE;
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/* Enable Period Interval Timer interrupt */
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AT91_SYS->ST_IER = AT91C_ST_PITS;
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}
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#endif
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