rtc-cmos: avoid spurious irqs
This fixes kernel http://bugzilla.kernel.org/show_bug.cgi?id=11112 (bogus
RTC update IRQs reported) for rtc-cmos, in two ways:
- When HPET is stealing the IRQs, use the first IRQ to grab
the seconds counter which will be monitored (instead of
using whatever was previously in that memory);
- In sane IRQ handling modes, scrub out old IRQ status before
enabling IRQs.
That latter is done by tightening up IRQ handling for rtc-cmos everywhere,
also ensuring that when HPET is used it's the only thing triggering IRQ
reports to userspace; net object shrink.
Also fix a bogus HPET message related to its RTC emulation.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Report-by: W Unruh <unruh@physics.ubc.ca>
Cc: Andrew Victor <avictor.za@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index e998465..6ea349a 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -235,11 +235,56 @@
return 0;
}
+static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
+{
+ unsigned char rtc_intr;
+
+ /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
+ * allegedly some older rtcs need that to handle irqs properly
+ */
+ rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
+
+ if (is_hpet_enabled())
+ return;
+
+ rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
+ if (is_intr(rtc_intr))
+ rtc_update_irq(cmos->rtc, 1, rtc_intr);
+}
+
+static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
+{
+ unsigned char rtc_control;
+
+ /* flush any pending IRQ status, notably for update irqs,
+ * before we enable new IRQs
+ */
+ rtc_control = CMOS_READ(RTC_CONTROL);
+ cmos_checkintr(cmos, rtc_control);
+
+ rtc_control |= mask;
+ CMOS_WRITE(rtc_control, RTC_CONTROL);
+ hpet_set_rtc_irq_bit(mask);
+
+ cmos_checkintr(cmos, rtc_control);
+}
+
+static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
+{
+ unsigned char rtc_control;
+
+ rtc_control = CMOS_READ(RTC_CONTROL);
+ rtc_control &= ~mask;
+ CMOS_WRITE(rtc_control, RTC_CONTROL);
+ hpet_mask_rtc_irq_bit(mask);
+
+ cmos_checkintr(cmos, rtc_control);
+}
+
static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
struct cmos_rtc *cmos = dev_get_drvdata(dev);
unsigned char mon, mday, hrs, min, sec;
- unsigned char rtc_control, rtc_intr;
if (!is_valid_irq(cmos->irq))
return -EIO;
@@ -266,15 +311,7 @@
spin_lock_irq(&rtc_lock);
/* next rtc irq must not be from previous alarm setting */
- rtc_control = CMOS_READ(RTC_CONTROL);
- rtc_control &= ~RTC_AIE;
- CMOS_WRITE(rtc_control, RTC_CONTROL);
- hpet_mask_rtc_irq_bit(RTC_AIE);
-
- rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
- rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
- if (is_intr(rtc_intr))
- rtc_update_irq(cmos->rtc, 1, rtc_intr);
+ cmos_irq_disable(cmos, RTC_AIE);
/* update alarm */
CMOS_WRITE(hrs, RTC_HOURS_ALARM);
@@ -293,16 +330,8 @@
*/
hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
- if (t->enabled) {
- rtc_control |= RTC_AIE;
- CMOS_WRITE(rtc_control, RTC_CONTROL);
- hpet_set_rtc_irq_bit(RTC_AIE);
-
- rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
- rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
- if (is_intr(rtc_intr))
- rtc_update_irq(cmos->rtc, 1, rtc_intr);
- }
+ if (t->enabled)
+ cmos_irq_enable(cmos, RTC_AIE);
spin_unlock_irq(&rtc_lock);
@@ -335,28 +364,17 @@
static int cmos_irq_set_state(struct device *dev, int enabled)
{
struct cmos_rtc *cmos = dev_get_drvdata(dev);
- unsigned char rtc_control, rtc_intr;
unsigned long flags;
if (!is_valid_irq(cmos->irq))
return -ENXIO;
spin_lock_irqsave(&rtc_lock, flags);
- rtc_control = CMOS_READ(RTC_CONTROL);
- if (enabled) {
- rtc_control |= RTC_PIE;
- hpet_set_rtc_irq_bit(RTC_PIE);
- } else {
- rtc_control &= ~RTC_PIE;
- hpet_mask_rtc_irq_bit(RTC_PIE);
- }
- CMOS_WRITE(rtc_control, RTC_CONTROL);
-
- rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
- rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
- if (is_intr(rtc_intr))
- rtc_update_irq(cmos->rtc, 1, rtc_intr);
+ if (enabled)
+ cmos_irq_enable(cmos, RTC_PIE);
+ else
+ cmos_irq_disable(cmos, RTC_PIE);
spin_unlock_irqrestore(&rtc_lock, flags);
return 0;
@@ -368,7 +386,6 @@
cmos_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
struct cmos_rtc *cmos = dev_get_drvdata(dev);
- unsigned char rtc_control, rtc_intr;
unsigned long flags;
switch (cmd) {
@@ -385,32 +402,20 @@
}
spin_lock_irqsave(&rtc_lock, flags);
- rtc_control = CMOS_READ(RTC_CONTROL);
switch (cmd) {
case RTC_AIE_OFF: /* alarm off */
- rtc_control &= ~RTC_AIE;
- hpet_mask_rtc_irq_bit(RTC_AIE);
+ cmos_irq_disable(cmos, RTC_AIE);
break;
case RTC_AIE_ON: /* alarm on */
- rtc_control |= RTC_AIE;
- hpet_set_rtc_irq_bit(RTC_AIE);
+ cmos_irq_enable(cmos, RTC_AIE);
break;
case RTC_UIE_OFF: /* update off */
- rtc_control &= ~RTC_UIE;
- hpet_mask_rtc_irq_bit(RTC_UIE);
+ cmos_irq_disable(cmos, RTC_UIE);
break;
case RTC_UIE_ON: /* update on */
- rtc_control |= RTC_UIE;
- hpet_set_rtc_irq_bit(RTC_UIE);
+ cmos_irq_enable(cmos, RTC_UIE);
break;
}
- CMOS_WRITE(rtc_control, RTC_CONTROL);
-
- rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
- rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
- if (is_intr(rtc_intr))
- rtc_update_irq(cmos->rtc, 1, rtc_intr);
-
spin_unlock_irqrestore(&rtc_lock, flags);
return 0;
}
@@ -571,7 +576,6 @@
* alarm woke the system.
*/
if (irqstat & RTC_AIE) {
- rtc_control = CMOS_READ(RTC_CONTROL);
rtc_control &= ~RTC_AIE;
CMOS_WRITE(rtc_control, RTC_CONTROL);
hpet_mask_rtc_irq_bit(RTC_AIE);
@@ -685,17 +689,10 @@
hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
- /* disable irqs.
- *
- * NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
- * allegedly some older rtcs need that to handle irqs properly
- */
- rtc_control = CMOS_READ(RTC_CONTROL);
- rtc_control &= ~(RTC_PIE | RTC_AIE | RTC_UIE);
- CMOS_WRITE(rtc_control, RTC_CONTROL);
- hpet_mask_rtc_irq_bit(RTC_PIE | RTC_AIE | RTC_UIE);
+ /* disable irqs */
+ cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
- CMOS_READ(RTC_INTR_FLAGS);
+ rtc_control = CMOS_READ(RTC_CONTROL);
spin_unlock_irq(&rtc_lock);
@@ -768,15 +765,8 @@
static void cmos_do_shutdown(void)
{
- unsigned char rtc_control;
-
spin_lock_irq(&rtc_lock);
- rtc_control = CMOS_READ(RTC_CONTROL);
- rtc_control &= ~RTC_IRQMASK;
- CMOS_WRITE(rtc_control, RTC_CONTROL);
- hpet_mask_rtc_irq_bit(RTC_IRQMASK);
-
- CMOS_READ(RTC_INTR_FLAGS);
+ cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
spin_unlock_irq(&rtc_lock);
}
@@ -817,7 +807,6 @@
spin_lock_irq(&rtc_lock);
cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
- unsigned char irqstat;
unsigned char mask;
if (do_wake)
@@ -828,10 +817,7 @@
CMOS_WRITE(tmp, RTC_CONTROL);
hpet_mask_rtc_irq_bit(mask);
- irqstat = CMOS_READ(RTC_INTR_FLAGS);
- irqstat &= (tmp & RTC_IRQMASK) | RTC_IRQF;
- if (is_intr(irqstat))
- rtc_update_irq(cmos->rtc, 1, irqstat);
+ cmos_checkintr(cmos, tmp);
}
spin_unlock_irq(&rtc_lock);
@@ -875,7 +861,7 @@
mask = CMOS_READ(RTC_INTR_FLAGS);
mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
- if (!is_intr(mask))
+ if (!is_hpet_enabled() || !is_intr(mask))
break;
/* force one-shot behavior if HPET blocked