Skip to content

Commit

Permalink
rtc-cmos: avoid spurious irqs
Browse files Browse the repository at this point in the history 
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>
  • Loading branch information
David Brownell authored and Linus Torvalds committed Jul 24, 2008
1 parent 449321b commit 7e2a31d
Show file tree
Hide file tree
Showing 2 changed files with 70 additions and 80 deletions.
10 changes: 7 additions & 3 deletions arch/x86/kernel/hpet.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -468,7 +468,7 @@ void hpet_disable(void)
#define RTC_NUM_INTS 1

static unsigned long hpet_rtc_flags;
static unsigned long hpet_prev_update_sec;
static int hpet_prev_update_sec;
static struct rtc_time hpet_alarm_time;
static unsigned long hpet_pie_count;
static unsigned long hpet_t1_cmp;
Expand Down Expand Up @@ -575,6 +575,9 @@ int hpet_set_rtc_irq_bit(unsigned long bit_mask)

hpet_rtc_flags |= bit_mask;

if ((bit_mask & RTC_UIE) && !(oldbits & RTC_UIE))
hpet_prev_update_sec = -1;

if (!oldbits)
hpet_rtc_timer_init();

Expand Down Expand Up @@ -652,7 +655,7 @@ static void hpet_rtc_timer_reinit(void)
if (hpet_rtc_flags & RTC_PIE)
hpet_pie_count += lost_ints;
if (printk_ratelimit())
printk(KERN_WARNING "rtc: lost %d interrupts\n",
printk(KERN_WARNING "hpet1: lost %d rtc interrupts\n",
lost_ints);
}
}
Expand All @@ -670,7 +673,8 @@ irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)

if (hpet_rtc_flags & RTC_UIE &&
curr_time.tm_sec != hpet_prev_update_sec) {
rtc_int_flag = RTC_UF;
if (hpet_prev_update_sec >= 0)
rtc_int_flag = RTC_UF;
hpet_prev_update_sec = curr_time.tm_sec;
}

Expand Down
140 changes: 63 additions & 77 deletions drivers/rtc/rtc-cmos.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -235,11 +235,56 @@ static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
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;
Expand All @@ -266,15 +311,7 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
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);
Expand All @@ -293,16 +330,8 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
*/
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);

Expand Down Expand Up @@ -335,28 +364,17 @@ static int cmos_irq_set_freq(struct device *dev, int freq)
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;
Expand All @@ -368,7 +386,6 @@ static int
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) {
Expand All @@ -385,32 +402,20 @@ cmos_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
}

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;
}
Expand Down Expand Up @@ -571,7 +576,6 @@ static irqreturn_t cmos_interrupt(int irq, void *p)
* 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);
Expand Down Expand Up @@ -685,17 +689,10 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
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);

Expand Down Expand Up @@ -768,15 +765,8 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)

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);
}

Expand Down Expand Up @@ -817,7 +807,6 @@ static int cmos_suspend(struct device *dev, pm_message_t mesg)
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)
Expand All @@ -828,10 +817,7 @@ static int cmos_suspend(struct device *dev, pm_message_t mesg)
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);

Expand Down Expand Up @@ -875,7 +861,7 @@ static int cmos_resume(struct device *dev)

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
Expand Down

0 comments on commit 7e2a31d

Please sign in to comment.