diff options
| author | Andrew Victor <andrew@sanpeople.com> | 2006-06-19 14:23:41 (GMT) |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2006-06-19 14:23:41 (GMT) |
| commit | 963151f2471d0e6475d8b2d3a005417aec1766f7 (patch) | |
| tree | 37602e1518fea1fea3243f7a527ea3c7deea3d34 /arch/arm | |
| parent | 91f8ed835ffb34b4108cc16eefd3303e4068bee0 (diff) | |
| download | linux-963151f2471d0e6475d8b2d3a005417aec1766f7.tar.xz | |
[ARM] 3579/1: AT91RM9200 Timer simplification
Patch from Andrew Victor
Use a global variable 'last_crtr' to store the time of the last timer
tick instead of the ST_RTAR register.
It's faster, frees up the ST_RTAR register for other uses, and hopefully
makes the code more understandable. [Patch from Peter Menzebach]
Also add the SA_TIMER flag to Timer IRQ. (It seems to be required for
the realtime preempt patch).
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/mach-at91rm9200/time.c | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/arch/arm/mach-at91rm9200/time.c b/arch/arm/mach-at91rm9200/time.c index 7ffcf44..36798a8 100644 --- a/arch/arm/mach-at91rm9200/time.c +++ b/arch/arm/mach-at91rm9200/time.c @@ -31,6 +31,8 @@ #include <asm/irq.h> #include <asm/mach/time.h> +static unsigned long last_crtr; + /* * The ST_CRTR is updated asynchronously to the master clock. It is therefore * necessary to read it twice (with the same value) to ensure accuracy. @@ -56,7 +58,7 @@ static unsigned long at91rm9200_gettimeoffset(void) { unsigned long elapsed; - elapsed = (read_CRTR() - at91_sys_read(AT91_ST_RTAR)) & AT91_ST_ALMV; + elapsed = (read_CRTR() - last_crtr) & AT91_ST_ALMV; return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH; } @@ -66,15 +68,12 @@ static unsigned long at91rm9200_gettimeoffset(void) */ static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) { - unsigned long rtar; - if (at91_sys_read(AT91_ST_SR) & AT91_ST_PITS) { /* This is a shared interrupt */ write_seqlock(&xtime_lock); - while (((read_CRTR() - at91_sys_read(AT91_ST_RTAR)) & AT91_ST_ALMV) >= LATCH) { + while (((read_CRTR() - last_crtr) & AT91_ST_ALMV) >= LATCH) { timer_tick(regs); - rtar = (at91_sys_read(AT91_ST_RTAR) + LATCH) & AT91_ST_ALMV; - at91_sys_write(AT91_ST_RTAR, rtar); + last_crtr = (last_crtr + LATCH) & AT91_ST_ALMV; } write_sequnlock(&xtime_lock); @@ -87,7 +86,7 @@ static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id, struct pt_r static struct irqaction at91rm9200_timer_irq = { .name = "at91_tick", - .flags = SA_SHIRQ | SA_INTERRUPT, + .flags = SA_SHIRQ | SA_INTERRUPT | SA_TIMER, .handler = at91rm9200_timer_interrupt }; |