1*796c0ad7SAishwarya PantWhat:		/dev/rtcX
2*796c0ad7SAishwarya PantDate:		April 2005
3*796c0ad7SAishwarya PantKernelVersion:	2.6.12
4*796c0ad7SAishwarya PantContact:	linux-rtc@vger.kernel.org
5*796c0ad7SAishwarya PantDescription:
6*796c0ad7SAishwarya Pant		The ioctl interface to drivers for real-time clocks (RTCs).
7*796c0ad7SAishwarya Pant		Following actions are supported:
8*796c0ad7SAishwarya Pant
9*796c0ad7SAishwarya Pant		* RTC_RD_TIME, RTC_SET_TIME: Read or set the RTC time. Time
10*796c0ad7SAishwarya Pant		  format is a Gregorian calendar date and 24 hour wall clock
11*796c0ad7SAishwarya Pant		  time.
12*796c0ad7SAishwarya Pant
13*796c0ad7SAishwarya Pant		* RTC_AIE_ON, RTC_AIE_OFF: Enable or disable the alarm interrupt
14*796c0ad7SAishwarya Pant		  for RTCs that support alarms
15*796c0ad7SAishwarya Pant
16*796c0ad7SAishwarya Pant		* RTC_ALM_READ, RTC_ALM_SET: Read or set the alarm time for
17*796c0ad7SAishwarya Pant		  RTCs that support alarms. Can be set upto 24 hours in the
18*796c0ad7SAishwarya Pant		  future. Requires a separate RTC_AIE_ON call to enable the
19*796c0ad7SAishwarya Pant		  alarm interrupt. (Prefer to use RTC_WKALM_*)
20*796c0ad7SAishwarya Pant
21*796c0ad7SAishwarya Pant		* RTC_WKALM_RD, RTC_WKALM_SET: For RTCs that support a more
22*796c0ad7SAishwarya Pant		  powerful interface, which can issue alarms beyond 24 hours and
23*796c0ad7SAishwarya Pant		  enable IRQs in the same request.
24*796c0ad7SAishwarya Pant
25*796c0ad7SAishwarya Pant		* RTC_PIE_ON, RTC_PIE_OFF: Enable or disable the periodic
26*796c0ad7SAishwarya Pant		  interrupt for RTCs that support periodic interrupts.
27*796c0ad7SAishwarya Pant
28*796c0ad7SAishwarya Pant		* RTC_UIE_ON, RTC_UIE_OFF: Enable or disable the update
29*796c0ad7SAishwarya Pant		  interrupt for RTCs that support it.
30*796c0ad7SAishwarya Pant
31*796c0ad7SAishwarya Pant		* RTC_IRQP_READ, RTC_IRQP_SET: Read or set the frequency for
32*796c0ad7SAishwarya Pant		  periodic interrupts for RTCs that support periodic interrupts.
33*796c0ad7SAishwarya Pant		  Requires a separate RTC_PIE_ON call to enable the periodic
34*796c0ad7SAishwarya Pant		  interrupts.
35*796c0ad7SAishwarya Pant
36*796c0ad7SAishwarya Pant		The ioctl() calls supported by the older /dev/rtc interface are
37*796c0ad7SAishwarya Pant		also supported by the newer RTC class framework. However,
38*796c0ad7SAishwarya Pant		because the chips and systems are not standardized, some PC/AT
39*796c0ad7SAishwarya Pant		functionality might not be provided. And in the same way, some
40*796c0ad7SAishwarya Pant		newer features -- including those enabled by ACPI -- are exposed
41*796c0ad7SAishwarya Pant		by the RTC class framework, but can't be supported by the older
42*796c0ad7SAishwarya Pant		driver.
43