Author: gonzo
Date: Fri Dec 28 01:38:43 2012
New Revision: 244758
URL: http://svnweb.freebsd.org/changeset/base/244758
Log:
Fix event timer on Raspberry Pi
- Disable interrupt when updating compare value in order to
make this operation atomical
- Increase minimum period for event timer. Systimer on BCM2835
is compare timer, so if minimum period is too small it might
be less then fraction of time between "read current value" and
"set compare timer" operations. It means that when timer is armed
actual counter value is more then compare value and it will take
whole cycle (~32sec for 1MHz timer) to fire interrupt.
Submitted by: Daisuke Aoyama <aoyama at peach.ne.jp>
Modified:
head/sys/arm/broadcom/bcm2835/bcm2835_systimer.c
Modified: head/sys/arm/broadcom/bcm2835/bcm2835_systimer.c
==============================================================================
--- head/sys/arm/broadcom/bcm2835/bcm2835_systimer.c Fri Dec 28 01:23:12
2012 (r244757)
+++ head/sys/arm/broadcom/bcm2835/bcm2835_systimer.c Fri Dec 28 01:38:43
2012 (r244758)
@@ -55,6 +55,7 @@ __FBSDID("$FreeBSD$");
#define DEFAULT_TIMER 3
#define DEFAULT_FREQUENCY 1000000
+#define MIN_PERIOD 100LLU
#define SYSTIMER_CS 0x00
#define SYSTIMER_CLO 0x04
@@ -123,17 +124,24 @@ bcm_systimer_start(struct eventtimer *et
struct systimer *st = et->et_priv;
uint32_t clo;
uint32_t count;
+ register_t s;
if (first != NULL) {
- st->enabled = 1;
count = (st->et.et_frequency * (first->frac >> 32)) >> 32;
if (first->sec != 0)
count += st->et.et_frequency * first->sec;
+ s = intr_disable();
clo = bcm_systimer_tc_read_4(SYSTIMER_CLO);
clo += count;
+ /*
+ * Clear pending interrupts
+ */
+ bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
bcm_systimer_tc_write_4(SYSTIMER_C0 + st->index*4, clo);
+ st->enabled = 1;
+ intr_restore(s);
return (0);
}
@@ -154,7 +162,13 @@ static int
bcm_systimer_intr(void *arg)
{
struct systimer *st = (struct systimer *)arg;
+ uint32_t cs;
+
+ cs = bcm_systimer_tc_read_4(SYSTIMER_CS);
+ if ((cs & (1 << st->index)) == 0)
+ return (FILTER_STRAY);
+ /* ACK interrupt */
bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
if (st->enabled) {
if (st->et.et_active) {
@@ -226,7 +240,7 @@ bcm_systimer_attach(device_t dev)
sc->st[DEFAULT_TIMER].et.et_frequency = sc->sysclk_freq;
sc->st[DEFAULT_TIMER].et.et_min_period.sec = 0;
sc->st[DEFAULT_TIMER].et.et_min_period.frac =
- ((0x00000002LLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency) <<
32;
+ ((MIN_PERIOD << 32) / sc->st[DEFAULT_TIMER].et.et_frequency) << 32;
sc->st[DEFAULT_TIMER].et.et_max_period.sec = 0xfffffff0U /
sc->st[DEFAULT_TIMER].et.et_frequency;
sc->st[DEFAULT_TIMER].et.et_max_period.frac =
((0xfffffffeLLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency) <<
32;
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