1What:		/dev/rtcX
2Date:		April 2005
3KernelVersion:	2.6.12
4Contact:	linux-rtc@vger.kernel.org
5Description:
6		The ioctl interface to drivers for real-time clocks (RTCs).
7		Following actions are supported:
8
9		* RTC_RD_TIME, RTC_SET_TIME: Read or set the RTC time. Time
10		  format is a Gregorian calendar date and 24 hour wall clock
11		  time.
12
13		* RTC_AIE_ON, RTC_AIE_OFF: Enable or disable the alarm interrupt
14		  for RTCs that support alarms
15
16		* RTC_ALM_READ, RTC_ALM_SET: Read or set the alarm time for
17		  RTCs that support alarms. Can be set upto 24 hours in the
18		  future. Requires a separate RTC_AIE_ON call to enable the
19		  alarm interrupt. (Prefer to use RTC_WKALM_*)
20
21		* RTC_WKALM_RD, RTC_WKALM_SET: For RTCs that support a more
22		  powerful interface, which can issue alarms beyond 24 hours and
23		  enable IRQs in the same request.
24
25		* RTC_PIE_ON, RTC_PIE_OFF: Enable or disable the periodic
26		  interrupt for RTCs that support periodic interrupts.
27
28		* RTC_UIE_ON, RTC_UIE_OFF: Enable or disable the update
29		  interrupt for RTCs that support it.
30
31		* RTC_IRQP_READ, RTC_IRQP_SET: Read or set the frequency for
32		  periodic interrupts for RTCs that support periodic interrupts.
33		  Requires a separate RTC_PIE_ON call to enable the periodic
34		  interrupts.
35
36		The ioctl() calls supported by the older /dev/rtc interface are
37		also supported by the newer RTC class framework. However,
38		because the chips and systems are not standardized, some PC/AT
39		functionality might not be provided. And in the same way, some
40		newer features -- including those enabled by ACPI -- are exposed
41		by the RTC class framework, but can't be supported by the older
42		driver.
43