| Aishwarya Pant | 796c0ad | 2018-01-01 23:01:24 +0530 | [diff] [blame] | 1 | What: /dev/rtcX |
| 2 | Date: April 2005 |
| 3 | KernelVersion: 2.6.12 |
| 4 | Contact: linux-rtc@vger.kernel.org |
| 5 | Description: |
| 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. |