CRIS: GENERIC_TIME fixes
GENERIC_TIME was not functional for CRIS, giving random backward
time jumps.
For CRISv32 implement a new clocksource using the free running counter
and ditch the arch_gettimeoffset.
The random time jumps still existed, but turned out to be the write_seqlock
which was missing around our do_timer() call.
So switch over to GENERIC_TIME using the clocksource for CRISv32.
CRISv10 doesn't have the free running counter needed for the
clocksource trick, but we can still use GENERIC_TIME with
arch_gettimeoffset.
Unfortunately, there were problems in using the prescaler register
to timer0 for the gettimeoffset calculation, so it is now ignored,
making our resolution worse by the tune of 40usec (0.4%) worst case.
At the same time, clean up some formatting and use NSEC_PER_SEC
instead of 1000000000.
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
diff --git a/arch/cris/arch-v10/kernel/time.c b/arch/cris/arch-v10/kernel/time.c
index 30adae5..00eb36f 100644
--- a/arch/cris/arch-v10/kernel/time.c
+++ b/arch/cris/arch-v10/kernel/time.c
@@ -61,66 +61,16 @@
unsigned long do_slow_gettimeoffset(void)
{
- unsigned long count, t1;
- unsigned long usec_count = 0;
- unsigned short presc_count;
-
- static unsigned long count_p = TIMER0_DIV;/* for the first call after boot */
- static unsigned long jiffies_p = 0;
-
- /*
- * cache volatile jiffies temporarily; we have IRQs turned off.
- */
- unsigned long jiffies_t;
+ unsigned long count;
/* The timer interrupt comes from Etrax timer 0. In order to get
* better precision, we check the current value. It might have
* underflowed already though.
*/
-
-#ifndef CONFIG_SVINTO_SIM
- /* Not available in the xsim simulator. */
count = *R_TIMER0_DATA;
- presc_count = *R_TIM_PRESC_STATUS;
- /* presc_count might be wrapped */
- t1 = *R_TIMER0_DATA;
- if (count != t1){
- /* it wrapped, read prescaler again... */
- presc_count = *R_TIM_PRESC_STATUS;
- count = t1;
- }
-#else
- count = 0;
- presc_count = 0;
-#endif
- jiffies_t = jiffies;
-
- /*
- * avoiding timer inconsistencies (they are rare, but they happen)...
- * there are one problem that must be avoided here:
- * 1. the timer counter underflows
- */
- if( jiffies_t == jiffies_p ) {
- if( count > count_p ) {
- /* Timer wrapped, use new count and prescale
- * increase the time corresponding to one jiffie
- */
- usec_count = 1000000/HZ;
- }
- } else
- jiffies_p = jiffies_t;
- count_p = count;
- if (presc_count >= PRESCALE_VALUE/2 ){
- presc_count = PRESCALE_VALUE - presc_count + PRESCALE_VALUE/2;
- } else {
- presc_count = PRESCALE_VALUE - presc_count - PRESCALE_VALUE/2;
- }
/* Convert timer value to usec */
- usec_count += ( (TIMER0_DIV - count) * (1000000/HZ)/TIMER0_DIV ) +
- (( (presc_count) * (1000000000/PRESCALE_FREQ))/1000);
-
- return usec_count;
+ return (TIMER0_DIV - count) * ((NSEC_PER_SEC/1000)/HZ)/TIMER0_DIV;
}
/* Excerpt from the Etrax100 HSDD about the built-in watchdog: