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| -rw-r--r-- | Documentation/ABI/testing/rtc-cdev | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/rtc-cdev b/Documentation/ABI/testing/rtc-cdev new file mode 100644 index 000000000..25910c3c3 --- /dev/null +++ b/Documentation/ABI/testing/rtc-cdev @@ -0,0 +1,50 @@ +What: /dev/rtcX +Date: April 2005 +KernelVersion: 2.6.12 +Contact: linux-rtc@vger.kernel.org +Description: + 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 upto 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. |