[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>
This commit is contained in:
parent
91f8ed835f
commit
963151f247
@ -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
|
||||
};
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user