• Christopher S. Hall's avatar
    time: Add cycles to nanoseconds translation · 9b57d91c
    Christopher S. Hall authored
    commit 6bd58f09 upstream.
    
    The timekeeping code does not currently provide a way to translate
    externally provided clocksource cycles to system time. The cycle count
    is always provided by the result clocksource read() method internal to
    the timekeeping code. The added function timekeeping_cycles_to_ns()
    calculated a nanosecond value from a cycle count that can be added to
    tk_read_base.base value yielding the current system time. This allows
    clocksource cycle values external to the timekeeping code to provide a
    cycle count that can be transformed to system time.
    
    Cc: Prarit Bhargava <prarit@redhat.com>
    Cc: Richard Cochran <richardcochran@gmail.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: kevin.b.stanton@intel.com
    Cc: kevin.j.clarke@intel.com
    Cc: hpa@zytor.com
    Cc: jeffrey.t.kirsher@intel.com
    Cc: netdev@vger.kernel.org
    Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarChristopher S. Hall <christopher.s.hall@intel.com>
    Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    9b57d91c
timekeeping.c 55.8 KB