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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051What: /dev/rtcXDate: April 2005KernelVersion: 2.6.12Contact: linux-rtc@vger.kernel.orgDescription: The ioctl interface to drivers for real-time clocks (RTCs). Following actions are supported:
* RTC_RD_TIME, RTC_SET_TIME: Read or set the RTC time. Time format is a Gregorian calendar date and 24 hour wall clock time.
* RTC_AIE_ON, RTC_AIE_OFF: Enable or disable the alarm interrupt for RTCs that support alarms
* RTC_ALM_READ, RTC_ALM_SET: Read or set the alarm time for RTCs that support alarms. Can be set up to 24 hours in the future. Requires a separate RTC_AIE_ON call to enable the alarm interrupt. (Prefer to use RTC_WKALM_*)
* RTC_WKALM_RD, RTC_WKALM_SET: For RTCs that support a more powerful interface, which can issue alarms beyond 24 hours and enable IRQs in the same request.
* RTC_PIE_ON, RTC_PIE_OFF: Enable or disable the periodic interrupt for RTCs that support periodic interrupts.
* RTC_UIE_ON, RTC_UIE_OFF: Enable or disable the update interrupt for RTCs that support it.
* RTC_IRQP_READ, RTC_IRQP_SET: Read or set the frequency for periodic interrupts for RTCs that support periodic interrupts. Requires a separate RTC_PIE_ON call to enable the periodic interrupts.
* RTC_VL_READ: Read the voltage inputs status of the RTC when supported. The value is a bit field of RTC_VL_*, giving the status of the main and backup voltages.
* RTC_VL_CLEAR: Clear the voltage status of the RTC. Some RTCs need user interaction when the backup power provider is replaced or charged to be able to clear the status.
The ioctl() calls supported by the older /dev/rtc interface are also supported by the newer RTC class framework. However, because the chips and systems are not standardized, some PC/AT functionality might not be provided. And in the same way, some newer features -- including those enabled by ACPI -- are exposed by the RTC class framework, but can't be supported by the older driver.