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50 lines
2.0 KiB
50 lines
2.0 KiB
What: /dev/rtcX |
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Date: April 2005 |
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KernelVersion: 2.6.12 |
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Contact: [email protected] |
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Description: |
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The ioctl interface to drivers for real-time clocks (RTCs). |
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Following actions are supported: |
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* RTC_RD_TIME, RTC_SET_TIME: Read or set the RTC time. Time |
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format is a Gregorian calendar date and 24 hour wall clock |
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time. |
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* RTC_AIE_ON, RTC_AIE_OFF: Enable or disable the alarm interrupt |
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for RTCs that support alarms |
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* RTC_ALM_READ, RTC_ALM_SET: Read or set the alarm time for |
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RTCs that support alarms. Can be set upto 24 hours in the |
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future. Requires a separate RTC_AIE_ON call to enable the |
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alarm interrupt. (Prefer to use RTC_WKALM_*) |
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* RTC_WKALM_RD, RTC_WKALM_SET: For RTCs that support a more |
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powerful interface, which can issue alarms beyond 24 hours and |
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enable IRQs in the same request. |
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* RTC_PIE_ON, RTC_PIE_OFF: Enable or disable the periodic |
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interrupt for RTCs that support periodic interrupts. |
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* RTC_UIE_ON, RTC_UIE_OFF: Enable or disable the update |
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interrupt for RTCs that support it. |
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* RTC_IRQP_READ, RTC_IRQP_SET: Read or set the frequency for |
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periodic interrupts for RTCs that support periodic interrupts. |
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Requires a separate RTC_PIE_ON call to enable the periodic |
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interrupts. |
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* RTC_VL_READ: Read the voltage inputs status of the RTC when |
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supported. The value is a bit field of RTC_VL_*, giving the |
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status of the main and backup voltages. |
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* RTC_VL_CLEAR: Clear the voltage status of the RTC. Some RTCs |
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need user interaction when the backup power provider is |
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replaced or charged to be able to clear the status. |
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The ioctl() calls supported by the older /dev/rtc interface are |
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also supported by the newer RTC class framework. However, |
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because the chips and systems are not standardized, some PC/AT |
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functionality might not be provided. And in the same way, some |
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newer features -- including those enabled by ACPI -- are exposed |
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by the RTC class framework, but can't be supported by the older |
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driver.
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