diff options
| author | Boris BREZILLON <boris.brezillon@free-electrons.com> | 2014-06-06 14:36:09 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2014-07-11 13:33:47 +0100 |
| commit | 6df2529a3af404bc367fcf37cd3203c1d4951675 (patch) | |
| tree | 0868fa85c627770d81eeea764a16a2d593bd097d /drivers | |
| parent | e70d6e73d06522b3c8c7a145a97e37387b2cb35b (diff) | |
rtc: rtc-at91rm9200: fix infinite wait for ACKUPD irq
commit 2fe121e1f5aa3bf31b418a9790db6c400e922291 upstream.
The rtc user must wait at least 1 sec between each time/calandar update
(see atmel's datasheet chapter "Updating Time/Calendar").
Use the 1Hz interrupt to update the at91_rtc_upd_rdy flag and wait for
the at91_rtc_wait_upd_rdy event if the rtc is not ready.
This patch fixes a deadlock in an uninterruptible wait when the RTC is
updated more than once every second. AFAICT the bug is here from the
beginning, but I think we should at least backport this fix to 3.10 and
the following longterm and stable releases.
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Reported-by: Bryan Evenson <bevenson@melinkcorp.com>
Tested-by: Bryan Evenson <bevenson@melinkcorp.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2:
- Adjust context
- at91_rtc_write() is called at91_sys_write()
- Use at91_sys_write() directly instead of the missing
at91_rtc_write_ier() and at91_rtc_write_idr()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/rtc/rtc-at91rm9200.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c index 15406d5e593e..feab6975d1ee 100644 --- a/drivers/rtc/rtc-at91rm9200.c +++ b/drivers/rtc/rtc-at91rm9200.c @@ -36,6 +36,7 @@ #define AT91_RTC_EPOCH 1900UL /* just like arch/arm/common/rtctime.c */ static DECLARE_COMPLETION(at91_rtc_updated); +static DECLARE_COMPLETION(at91_rtc_upd_rdy); static unsigned int at91_alarm_year = AT91_RTC_EPOCH; /* @@ -97,6 +98,8 @@ static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); + wait_for_completion(&at91_rtc_upd_rdy); + /* Stop Time/Calendar from counting */ cr = at91_sys_read(AT91_RTC_CR); at91_sys_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM); @@ -119,7 +122,9 @@ static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) /* Restart Time/Calendar */ cr = at91_sys_read(AT91_RTC_CR); + at91_sys_write(AT91_RTC_SCCR, AT91_RTC_SECEV); at91_sys_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM)); + at91_sys_write(AT91_RTC_IER, AT91_RTC_SECEV); return 0; } @@ -226,8 +231,10 @@ static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id) if (rtsr) { /* this interrupt is shared! Is it ours? */ if (rtsr & AT91_RTC_ALARM) events |= (RTC_AF | RTC_IRQF); - if (rtsr & AT91_RTC_SECEV) - events |= (RTC_UF | RTC_IRQF); + if (rtsr & AT91_RTC_SECEV) { + complete(&at91_rtc_upd_rdy); + at91_sys_write(AT91_RTC_IDR, AT91_RTC_SECEV); + } if (rtsr & AT91_RTC_ACKUPD) complete(&at91_rtc_updated); @@ -291,6 +298,11 @@ static int __init at91_rtc_probe(struct platform_device *pdev) } platform_set_drvdata(pdev, rtc); + /* enable SECEV interrupt in order to initialize at91_rtc_upd_rdy + * completion. + */ + at91_sys_write(AT91_RTC_IER, AT91_RTC_SECEV); + printk(KERN_INFO "AT91 Real Time Clock driver.\n"); return 0; } |