18c2ecf20Sopenharmony_ciWhat: /dev/rtcX 28c2ecf20Sopenharmony_ciDate: April 2005 38c2ecf20Sopenharmony_ciKernelVersion: 2.6.12 48c2ecf20Sopenharmony_ciContact: linux-rtc@vger.kernel.org 58c2ecf20Sopenharmony_ciDescription: 68c2ecf20Sopenharmony_ci The ioctl interface to drivers for real-time clocks (RTCs). 78c2ecf20Sopenharmony_ci Following actions are supported: 88c2ecf20Sopenharmony_ci 98c2ecf20Sopenharmony_ci * RTC_RD_TIME, RTC_SET_TIME: Read or set the RTC time. Time 108c2ecf20Sopenharmony_ci format is a Gregorian calendar date and 24 hour wall clock 118c2ecf20Sopenharmony_ci time. 128c2ecf20Sopenharmony_ci 138c2ecf20Sopenharmony_ci * RTC_AIE_ON, RTC_AIE_OFF: Enable or disable the alarm interrupt 148c2ecf20Sopenharmony_ci for RTCs that support alarms 158c2ecf20Sopenharmony_ci 168c2ecf20Sopenharmony_ci * RTC_ALM_READ, RTC_ALM_SET: Read or set the alarm time for 178c2ecf20Sopenharmony_ci RTCs that support alarms. Can be set upto 24 hours in the 188c2ecf20Sopenharmony_ci future. Requires a separate RTC_AIE_ON call to enable the 198c2ecf20Sopenharmony_ci alarm interrupt. (Prefer to use RTC_WKALM_*) 208c2ecf20Sopenharmony_ci 218c2ecf20Sopenharmony_ci * RTC_WKALM_RD, RTC_WKALM_SET: For RTCs that support a more 228c2ecf20Sopenharmony_ci powerful interface, which can issue alarms beyond 24 hours and 238c2ecf20Sopenharmony_ci enable IRQs in the same request. 248c2ecf20Sopenharmony_ci 258c2ecf20Sopenharmony_ci * RTC_PIE_ON, RTC_PIE_OFF: Enable or disable the periodic 268c2ecf20Sopenharmony_ci interrupt for RTCs that support periodic interrupts. 278c2ecf20Sopenharmony_ci 288c2ecf20Sopenharmony_ci * RTC_UIE_ON, RTC_UIE_OFF: Enable or disable the update 298c2ecf20Sopenharmony_ci interrupt for RTCs that support it. 308c2ecf20Sopenharmony_ci 318c2ecf20Sopenharmony_ci * RTC_IRQP_READ, RTC_IRQP_SET: Read or set the frequency for 328c2ecf20Sopenharmony_ci periodic interrupts for RTCs that support periodic interrupts. 338c2ecf20Sopenharmony_ci Requires a separate RTC_PIE_ON call to enable the periodic 348c2ecf20Sopenharmony_ci interrupts. 358c2ecf20Sopenharmony_ci 368c2ecf20Sopenharmony_ci * RTC_VL_READ: Read the voltage inputs status of the RTC when 378c2ecf20Sopenharmony_ci supported. The value is a bit field of RTC_VL_*, giving the 388c2ecf20Sopenharmony_ci status of the main and backup voltages. 398c2ecf20Sopenharmony_ci 408c2ecf20Sopenharmony_ci * RTC_VL_CLEAR: Clear the voltage status of the RTC. Some RTCs 418c2ecf20Sopenharmony_ci need user interaction when the backup power provider is 428c2ecf20Sopenharmony_ci replaced or charged to be able to clear the status. 438c2ecf20Sopenharmony_ci 448c2ecf20Sopenharmony_ci The ioctl() calls supported by the older /dev/rtc interface are 458c2ecf20Sopenharmony_ci also supported by the newer RTC class framework. However, 468c2ecf20Sopenharmony_ci because the chips and systems are not standardized, some PC/AT 478c2ecf20Sopenharmony_ci functionality might not be provided. And in the same way, some 488c2ecf20Sopenharmony_ci newer features -- including those enabled by ACPI -- are exposed 498c2ecf20Sopenharmony_ci by the RTC class framework, but can't be supported by the older 508c2ecf20Sopenharmony_ci driver. 51