diff options
Diffstat (limited to 'cpu/nios2/interrupts.c')
| -rw-r--r-- | cpu/nios2/interrupts.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/cpu/nios2/interrupts.c b/cpu/nios2/interrupts.c index 5c3b5e6..b552db4 100644 --- a/cpu/nios2/interrupts.c +++ b/cpu/nios2/interrupts.c @@ -56,7 +56,40 @@ volatile ulong timestamp = 0; void reset_timer (void) { + nios_timer_t *tmr =(nios_timer_t *)CONFIG_SYS_NIOS_TMRBASE; + + /* From Embedded Peripherals Handbook: + * + * "When the hardware is configured with Writeable period + * disabled, writing to one of the period_n registers causes + * the counter to reset to the fixed Timeout Period specified + * at system generation time." + * + * Here we force a reload to prevent early timeouts from + * get_timer() when the interrupt period is greater than + * than 1 msec. + * + * Simply write to periodl with its own value to force an + * internal counter reload, THEN reset the timestamp. + */ + writel (readl (&tmr->periodl), &tmr->periodl); timestamp = 0; + + /* From Embedded Peripherals Handbook: + * + * "Writing to one of the period_n registers stops the internal + * counter, except when the hardware is configured with Start/Stop + * control bits off. If Start/Stop control bits is off, writing + * either register does not stop the counter." + * + * In order to accomodate either configuration, the control + * register is re-written. If the counter is stopped, it will + * be restarted. If it is running, the write is essentially + * a nop. + */ + writel (NIOS_TIMER_ITO | NIOS_TIMER_CONT | NIOS_TIMER_START, + &tmr->control); + } ulong get_timer (ulong base) |