diff options
Diffstat (limited to 'cpu/nios2/interrupts.c')
-rw-r--r-- | cpu/nios2/interrupts.c | 49 |
1 files changed, 41 insertions, 8 deletions
diff --git a/cpu/nios2/interrupts.c b/cpu/nios2/interrupts.c index 1c3566e..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) @@ -81,7 +114,7 @@ void tmr_isr (void *arg) /* Interrupt is cleared by writing anything to the * status register. */ - writel (&tmr->status, 0); + writel (0, &tmr->status); timestamp += CONFIG_SYS_NIOS_TMRMS; #ifdef CONFIG_STATUS_LED status_led_tick(timestamp); @@ -92,16 +125,16 @@ static void tmr_init (void) { nios_timer_t *tmr =(nios_timer_t *)CONFIG_SYS_NIOS_TMRBASE; - writel (&tmr->status, 0); - writel (&tmr->control, 0); - writel (&tmr->control, NIOS_TIMER_STOP); + writel (0, &tmr->status); + writel (0, &tmr->control); + writel (NIOS_TIMER_STOP, &tmr->control); #if defined(CONFIG_SYS_NIOS_TMRCNT) - writel (&tmr->periodl, CONFIG_SYS_NIOS_TMRCNT & 0xffff); - writel (&tmr->periodh, (CONFIG_SYS_NIOS_TMRCNT >> 16) & 0xffff); + writel (CONFIG_SYS_NIOS_TMRCNT & 0xffff, &tmr->periodl); + writel ((CONFIG_SYS_NIOS_TMRCNT >> 16) & 0xffff, &tmr->periodh); #endif - writel (&tmr->control, NIOS_TIMER_ITO | NIOS_TIMER_CONT | - NIOS_TIMER_START ); + writel (NIOS_TIMER_ITO | NIOS_TIMER_CONT | NIOS_TIMER_START, + &tmr->control); irq_install_handler (CONFIG_SYS_NIOS_TMRIRQ, tmr_isr, (void *)tmr); } |