From 9d9d415f0048e4f7a6109595e2d1657850569c6c Mon Sep 17 00:00:00 2001 From: "Radu Pirea (NXP OSS)" Date: Mon, 10 May 2021 18:34:32 +0300 Subject: ptp: ptp_clock: make scaled_ppm_to_ppb static inline Make scaled_ppm_to_ppb static inline to be able to build drivers that use this function even with PTP_1588_CLOCK disabled. Signed-off-by: Radu Pirea (NXP OSS) Signed-off-by: David S. Miller --- include/linux/ptp_clock_kernel.h | 34 ++++++++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 8 deletions(-) (limited to 'include/linux/ptp_clock_kernel.h') diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h index 0d47fd33b228..a311bddd9e85 100644 --- a/include/linux/ptp_clock_kernel.h +++ b/include/linux/ptp_clock_kernel.h @@ -186,6 +186,32 @@ struct ptp_clock_event { }; }; +/** + * scaled_ppm_to_ppb() - convert scaled ppm to ppb + * + * @ppm: Parts per million, but with a 16 bit binary fractional field + */ +static inline s32 scaled_ppm_to_ppb(long ppm) +{ + /* + * The 'freq' field in the 'struct timex' is in parts per + * million, but with a 16 bit binary fractional field. + * + * We want to calculate + * + * ppb = scaled_ppm * 1000 / 2^16 + * + * which simplifies to + * + * ppb = scaled_ppm * 125 / 2^13 + */ + s64 ppb = 1 + ppm; + + ppb *= 125; + ppb >>= 13; + return (s32)ppb; +} + #if IS_REACHABLE(CONFIG_PTP_1588_CLOCK) /** @@ -229,14 +255,6 @@ extern void ptp_clock_event(struct ptp_clock *ptp, extern int ptp_clock_index(struct ptp_clock *ptp); -/** - * scaled_ppm_to_ppb() - convert scaled ppm to ppb - * - * @ppm: Parts per million, but with a 16 bit binary fractional field - */ - -extern s32 scaled_ppm_to_ppb(long ppm); - /** * ptp_find_pin() - obtain the pin index of a given auxiliary function * -- cgit v1.2.3