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Diffstat (limited to 'include/asm-arm/arch-sa1100/time.h')
| -rw-r--r-- | include/asm-arm/arch-sa1100/time.h | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/include/asm-arm/arch-sa1100/time.h b/include/asm-arm/arch-sa1100/time.h new file mode 100644 index 000000000..205a317a0 --- /dev/null +++ b/include/asm-arm/arch-sa1100/time.h @@ -0,0 +1,60 @@ +/* + * linux/include/asm-arm/arch-sa1100/time.h + * + * Copyright (C) 1998 Deborah Wallach. + * Twiddles (C) 1999 Hugo Fiennes <hugo@empeg.com> + * + * 2000/03/29 (C) Nicolas Pitre <nico@cam.org> + * Rewritten: big cleanup, much simpler, better HZ acuracy. + * + */ + +#include <asm/arch/hardware.h> +#include <asm/arch/irqs.h> + + +/* IRQs are disabled before entering here from do_gettimeofday() */ +static unsigned long sa1100_gettimeoffset (void) +{ + unsigned long ticks_to_match, elapsed, usec; + + /* Get ticks before next timer match */ + ticks_to_match = OSMR0 - OSCR; + + /* We need elapsed ticks since last match */ + elapsed = LATCH - ticks_to_match; + + /* Now convert them to usec */ + usec = (unsigned long)(elapsed*tick)/LATCH; + + return usec; +} + + +static void sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) +{ + int next_match; + + /* Loop until we get ahead of the free running timer. + * This ensures an exact clock tick count and time acuracy. + * Should be IRQ race free. + */ + do { + do_timer(regs); + OSSR = OSSR_M0; /* Clear match on timer 0 */ + next_match = (OSMR0 += LATCH); + } while( (signed long)(next_match - OSCR) <= 0 ); +} + + +extern inline void setup_timer (void) +{ + gettimeoffset = sa1100_gettimeoffset; + timer_irq.handler = sa1100_timer_interrupt; + OSMR0 = 0; /* set initial match at 0 */ + OSSR = 0xf; /* clear status on all timers */ + setup_arm_irq(IRQ_OST0, &timer_irq); + OIER |= OIER_E0; /* enable match on timer 0 to cause interrupts */ + OSCR = 0; /* initialize free-running timer, force first match */ +} + |