linux-imx

#

# RTC class/drivers configuration

#

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config RTC_LIB

    bool

​

config RTC_MC146818_LIB

    bool

    select RTC_LIB

​

menuconfig RTC_CLASS

    bool "Real Time Clock"

    default n

    depends on !S390 && !UML

    select RTC_LIB

    help

      Generic RTC class support. If you say yes here, you will

      be allowed to plug one or more RTCs to your system. You will

      probably want to enable one or more of the interfaces below.

​

if RTC_CLASS

​

config RTC_HCTOSYS

    bool "Set system time from RTC on startup and resume"

    default y

    help

      If you say yes here, the system time (wall clock) will be set using

      the value read from a specified RTC device. This is useful to avoid

      unnecessary fsck runs at boot time, and to network better.

​

config RTC_HCTOSYS_DEVICE

    string "RTC used to set the system time"

    depends on RTC_HCTOSYS

    default "rtc0"

    help

      The RTC device that will be used to (re)initialize the system

      clock, usually rtc0. Initialization is done when the system

      starts up, and when it resumes from a low power state. This

      device should record time in UTC, since the kernel won't do

      timezone correction.

​

      The driver for this RTC device must be loaded before late_initcall

      functions run, so it must usually be statically linked.

​

      This clock should be battery-backed, so that it reads the correct

      time when the system boots from a power-off state. Otherwise, your

      system will need an external clock source (like an NTP server).

​

      If the clock you specify here is not battery backed, it may still

      be useful to reinitialize system time when resuming from system

      sleep states. Do not specify an RTC here unless it stays powered

      during all this system's supported sleep states.

​

config RTC_SYSTOHC

    bool "Set the RTC time based on NTP synchronization"

    default y

    help

      If you say yes here, the system time (wall clock) will be stored

      in the RTC specified by RTC_HCTOSYS_DEVICE approximately every 11

      minutes if userspace reports synchronized NTP status.

​

config RTC_SYSTOHC_DEVICE

    string "RTC used to synchronize NTP adjustment"

    depends on RTC_SYSTOHC

    default RTC_HCTOSYS_DEVICE if RTC_HCTOSYS

    default "rtc0"

    help

      The RTC device used for NTP synchronization. The main difference

      between RTC_HCTOSYS_DEVICE and RTC_SYSTOHC_DEVICE is that this

      one can sleep when setting time, because it runs in the workqueue

      context.

​

config RTC_DEBUG

    bool "RTC debug support"

    help

      Say yes here to enable debugging support in the RTC framework

      and individual RTC drivers.

​

config RTC_NVMEM

    bool "RTC non volatile storage support"

    select NVMEM

    default RTC_CLASS

    help

      Say yes here to add support for the non volatile (often battery

      backed) storage present on RTCs.

​

comment "RTC interfaces"

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config RTC_INTF_SYSFS

    bool "/sys/class/rtc/rtcN (sysfs)"

    depends on SYSFS