projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 796c0ad7 AP |
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 | ||
| 790a19f1 AB |
36 | * RTC_VL_READ: Read the voltage inputs status of the RTC when |
| 37 | supported. The value is a bit field of RTC_VL_*, giving the | |
| 38 | status of the main and backup voltages. | |
| 39 | ||
| 40 | * RTC_VL_CLEAR: Clear the voltage status of the RTC. Some RTCs | |
| 41 | need user interaction when the backup power provider is | |
| 42 | replaced or charged to be able to clear the status. | |
| 43 | ||
| 796c0ad7 AP |
44 | The ioctl() calls supported by the older /dev/rtc interface are |
| 45 | also supported by the newer RTC class framework. However, | |
| 46 | because the chips and systems are not standardized, some PC/AT | |
| 47 | functionality might not be provided. And in the same way, some | |
| 48 | newer features -- including those enabled by ACPI -- are exposed | |
| 49 | by the RTC class framework, but can't be supported by the older | |
| 50 | driver. |