forked from luck/tmp_suning_uos_patched
3392b309db
Fix an overrun in the AT91SAM9 gettimeoffset() function. This causes the time value returned by gettimeofday() to jump "backwards". Original patch from Michel Benoit. Signed-off-by: Andrew Victor <andrew@sanpeople.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/*
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* linux/arch/arm/mach-at91/at91sam926x_time.c
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*
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* Copyright (C) 2005-2006 M. Amine SAYA, ATMEL Rousset, France
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* Revision 2005 M. Nicolas Diremdjian, ATMEL Rousset, France
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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 version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/time.h>
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#include <asm/hardware.h>
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#include <asm/io.h>
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#include <asm/mach/time.h>
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#include <asm/arch/at91_pit.h>
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#define PIT_CPIV(x) ((x) & AT91_PIT_CPIV)
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#define PIT_PICNT(x) (((x) & AT91_PIT_PICNT) >> 20)
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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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*/
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static unsigned long at91sam926x_gettimeoffset(void)
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{
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unsigned long elapsed;
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unsigned long t = at91_sys_read(AT91_PIT_PIIR);
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elapsed = (PIT_PICNT(t) * LATCH) + PIT_CPIV(t); /* hardware clock cycles */
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return (unsigned long)(elapsed * jiffies_to_usecs(1)) / 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 irqreturn_t at91sam926x_timer_interrupt(int irq, void *dev_id)
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{
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volatile long nr_ticks;
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if (at91_sys_read(AT91_PIT_SR) & AT91_PIT_PITS) { /* This is a shared interrupt */
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write_seqlock(&xtime_lock);
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/* Get number to ticks performed before interrupt and clear PIT interrupt */
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nr_ticks = PIT_PICNT(at91_sys_read(AT91_PIT_PIVR));
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do {
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timer_tick();
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nr_ticks--;
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} while (nr_ticks);
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write_sequnlock(&xtime_lock);
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return IRQ_HANDLED;
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} else
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return IRQ_NONE; /* not handled */
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}
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static struct irqaction at91sam926x_timer_irq = {
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.name = "at91_tick",
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.flags = IRQF_SHARED | IRQF_DISABLED | IRQF_TIMER,
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.handler = at91sam926x_timer_interrupt
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};
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void at91sam926x_timer_reset(void)
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{
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/* Disable timer */
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at91_sys_write(AT91_PIT_MR, 0);
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/* Clear any pending interrupts */
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(void) at91_sys_read(AT91_PIT_PIVR);
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/* Set Period Interval timer and enable its interrupt */
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at91_sys_write(AT91_PIT_MR, (LATCH & AT91_PIT_PIV) | AT91_PIT_PITIEN | AT91_PIT_PITEN);
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}
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/*
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* Set up timer interrupt.
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*/
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void __init at91sam926x_timer_init(void)
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{
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/* Initialize and enable the timer */
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at91sam926x_timer_reset();
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/* Make IRQs happen for the system timer. */
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setup_irq(AT91_ID_SYS, &at91sam926x_timer_irq);
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}
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#ifdef CONFIG_PM
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static void at91sam926x_timer_suspend(void)
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{
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/* Disable timer */
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at91_sys_write(AT91_PIT_MR, 0);
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}
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#else
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#define at91sam926x_timer_suspend NULL
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#endif
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struct sys_timer at91sam926x_timer = {
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.init = at91sam926x_timer_init,
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.offset = at91sam926x_gettimeoffset,
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.suspend = at91sam926x_timer_suspend,
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.resume = at91sam926x_timer_reset,
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};
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