From 7e2a31da854dcf8324012a83a31b40bc11e52589 Mon Sep 17 00:00:00 2001 From: David Brownell Date: Wed, 23 Jul 2008 21:30:47 -0700 Subject: [PATCH] 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 Report-by: W Unruh Cc: Andrew Victor Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/kernel/hpet.c | 10 ++- drivers/rtc/rtc-cmos.c | 140 +++++++++++++++++++---------------------- 2 files changed, 70 insertions(+), 80 deletions(-) diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 0ea6a19bfdf..ad2b15a1334 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -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; @@ -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(); @@ -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); } } @@ -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; } diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index e9984650ea9..6ea349aba3b 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -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; @@ -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); @@ -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); @@ -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; @@ -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) { @@ -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; } @@ -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); @@ -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); @@ -768,15 +765,8 @@ cleanup0: 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 @@ 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) @@ -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); @@ -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 -- 2.41.1