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path: root/drivers/rtc/rtc-lib.c
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2010-12-10RTC: Rework RTC code to use timerqueue for eventsJohn Stultz
This patch reworks a large portion of the generic RTC code to in-effect virtualize the rtc interrupt code. The current RTC interface is very much a raw hardware interface. Via the proc, /dev/, or sysfs interfaces, applciations can set the hardware to trigger interrupts in one of three modes: AIE: Alarm interrupt UIE: Update interrupt (ie: once per second) PIE: Periodic interrupt (sub-second irqs) The problem with this interface is that it limits the RTC hardware so it can only be used by one application at a time. The purpose of this patch is to extend the RTC code so that we can multiplex multiple applications event needs onto a single RTC device. This is done by utilizing the timerqueue infrastructure to manage a list of events, which cause the RTC hardware to be programmed to fire an interrupt for the next event in the list. In order to preserve the functionality of the exsting proc,/dev/ and sysfs interfaces, we emulate the different interrupt modes as follows: AIE: We create a rtc_timer dedicated to AIE mode interrupts. There is only one per device, so we don't change existing interface semantics. UIE: Again, a dedicated rtc_timer, set for periodic mode, is used to emulate UIE interrupts. Again, only one per device. PIE: Since PIE mode interrupts fire faster then the RTC's clock read granularity, we emulate PIE mode interrupts using a hrtimer. Again, one per device. With this patch, the rtctest.c application in Documentation/rtc.txt passes fine on x86 hardware. However, there may very well still be bugs, so greatly I'd appreciate any feedback or testing! Signed-off-by: John Stultz <john.stultz@linaro.org> LKML Reference: <1290136329-18291-4-git-send-email-john.stultz@linaro.org> Acked-by: Alessandro Zummo <a.zummo@towertech.it> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> CC: Alessandro Zummo <a.zummo@towertech.it> CC: Thomas Gleixner <tglx@linutronix.de> CC: Richard Cochran <richardcochran@gmail.com>
2009-04-01rtc: convert LEAP_YEAR into an inlineAndrew Morton
- the LEAP_YEAR macro is buggy - it references its arg multiple times. Fix this by turning it into a C function. - give it a more approriate name - Move it to rtc.h so that other .c files can use it, instead of copying it. Cc: dann frazier <dannf@hp.com> Acked-by: Alessandro Zummo <alessandro.zummo@towertech.it> Cc: stephane eranian <eranian@googlemail.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-09-02rtc_time_to_tm: fix signed/unsigned arithmeticJan Altenberg
commit 945185a69daa457c4c5e46e47f4afad7dcea734f ("rtc: rtc_time_to_tm: use unsigned arithmetic") changed the some types in rtc_time_to_tm() to unsigned: void rtc_time_to_tm(unsigned long time, struct rtc_time *tm) { - register int days, month, year; + unsigned int days, month, year; This doesn't work for all cases, because days is checked for < 0 later on: if (days < 0) { year -= 1; days += 365 + LEAP_YEAR(year); } I think the correct fix would be to keep days signed and do an appropriate cast later on. Signed-off-by: Jan Altenberg <jan.altenberg@linutronix.de> Cc: Maciej W. Rozycki <macro@linux-mips.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: David Brownell <david-b@pacbell.net> Cc: Dmitri Vorobiev <dmitri.vorobiev@gmail.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-13rtc: rtc_time_to_tm: use unsigned arithmeticMaciej W. Rozycki
The input argument to rtc_time_to_tm() is unsigned as well as are members of the output structure. However signed arithmetic is used within for calculations leading to incorrect results for input values outside the signed positive range. If this happens the time of day returned is out of range. Found the problem when fiddling with the RTC and the driver where year was set to an unexpectedly large value like 2070, e.g.: rtc0: setting system clock to 2070-01-01 1193046:71582832:26 UTC (3155760954) while it should be: rtc0: setting system clock to 2070-01-01 00:15:54 UTC (3155760954) Changing types to unsigned fixes the problem. [akpm@linux-foundation.org: remove old-fashioned `register' keyword] Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: David Brownell <david-b@pacbell.net> Cc: Dmitri Vorobiev <dmitri.vorobiev@gmail.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08revert "rtc: Add rtc_merge_alarm()"Andrew Morton
David says "884b4aaaa242a2db8c8252796f0118164a680ab5 should be reverted. It added an rtc_merge_alarm() call to the 2.6.20 kernel, which hasn't yet been used by any in-tree driver; this patch obviates the need for that call, and uses a more robust approach." Cc: Scott Wood <scottwood@freescale.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-12-10[PATCH] rtc: Add rtc_merge_alarm()Scott Wood
Add rtc_merge_alarm(), which can be used by rtc drivers to turn a partially specified alarm expiry (i.e. most significant fields set to -1, as with the RTC_ALM_SET ioctl()) into a fully specified expiry. If the most significant specified field is earlier than the current time, the least significant unspecified field is incremented. Signed-off-by: Scott Wood <scottwood@freescale.com> Acked-by: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01[PATCH] RTC class: error checksDavid Brownell
The rtc_is_valid_tm() routine needs to treat some of the fields it checks as unsigned, to prevent wrongly accepting invalid rtc_time structs; this is the same approach used elsewhere in the RTC code for such tests. Conversely, rtc_proc_show() is missing one invalid-day-of-month test that rtc_is_valid_tm() makes: there is no day zero. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-25[PATCH] RTC: Add rtc_year_days() to calculate tm_ydayAndrew Victor
RTC: Add exported function rtc_year_days() to calculate the tm_yday value. Signed-off-by: Andrew Victor <andrew@sanpeople.com> Signed-off-by: Alessandro Zummo <a.zummo@towertech.it> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27[PATCH] RTC Subsystem: library functionsAlessandro Zummo
RTC and date/time related functions. Signed-off-by: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>