From b9a61b97798ca6d0c856a217e61e2177bd8f6eae Mon Sep 17 00:00:00 2001 From: Jacob Keller Date: Fri, 28 Oct 2022 04:04:12 -0700 Subject: ptp: add missing documentation for parameters The ptp_find_pin_unlocked function and the ptp_system_timestamp structure didn't document their parameters and fields. Fix this. Signed-off-by: Jacob Keller Acked-by: Richard Cochran Signed-off-by: David S. Miller --- include/linux/ptp_clock_kernel.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h index 92b44161408e..ad4aaadc2f7a 100644 --- a/include/linux/ptp_clock_kernel.h +++ b/include/linux/ptp_clock_kernel.h @@ -45,6 +45,8 @@ struct system_device_crosststamp; /** * struct ptp_system_timestamp - system time corresponding to a PHC timestamp + * @pre_ts: system timestamp before capturing PHC + * @post_ts: system timestamp after capturing PHC */ struct ptp_system_timestamp { struct timespec64 pre_ts; @@ -316,6 +318,11 @@ int ptp_find_pin(struct ptp_clock *ptp, * should most likely call ptp_find_pin() directly from their * ptp_clock_info::enable() method. * +* @ptp: The clock obtained from ptp_clock_register(). +* @func: One of the ptp_pin_function enumerated values. +* @chan: The particular functional channel to find. +* Return: Pin index in the range of zero to ptp_clock_caps.n_pins - 1, +* or -1 if the auxiliary function cannot be found. */ int ptp_find_pin_unlocked(struct ptp_clock *ptp, -- cgit v1.2.3 From 1060707e380994e7c9b754b6eb74f25459b4a5b3 Mon Sep 17 00:00:00 2001 From: Jacob Keller Date: Fri, 28 Oct 2022 04:04:13 -0700 Subject: ptp: introduce helpers to adjust by scaled parts per million Many drivers implement the .adjfreq or .adjfine PTP op function with the same basic logic: 1. Determine a base frequency value 2. Multiply this by the abs() of the requested adjustment, then divide by the appropriate divisor (1 billion, or 65,536 billion). 3. Add or subtract this difference from the base frequency to calculate a new adjustment. A few drivers need the difference and direction rather than the combined new increment value. I recently converted the Intel drivers to .adjfine and the scaled parts per million (65.536 parts per billion) logic. To avoid overflow with minimal loss of precision, mul_u64_u64_div_u64 was used. The basic logic used by all of these drivers is very similar, and leads to a lot of duplicate code to perform the same task. Rather than keep this duplicate code, introduce diff_by_scaled_ppm and adjust_by_scaled_ppm. These helper functions calculate the difference or adjustment necessary based on the scaled parts per million input. The diff_by_scaled_ppm function returns true if the difference should be subtracted, and false otherwise. Update the Intel drivers to use the new helper functions. Other vendor drivers will be converted to .adjfine and this helper function in the following changes. Signed-off-by: Jacob Keller Acked-by: Richard Cochran Signed-off-by: David S. Miller --- include/linux/ptp_clock_kernel.h | 46 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) (limited to 'include/linux') diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h index ad4aaadc2f7a..f4781c5766d6 100644 --- a/include/linux/ptp_clock_kernel.h +++ b/include/linux/ptp_clock_kernel.h @@ -248,6 +248,52 @@ static inline long scaled_ppm_to_ppb(long ppm) return (long)ppb; } +/** + * diff_by_scaled_ppm - Calculate difference using scaled ppm + * @base: the base increment value to adjust + * @scaled_ppm: scaled parts per million to adjust by + * @diff: on return, the absolute value of calculated diff + * + * Calculate the difference to adjust the base increment using scaled parts + * per million. + * + * Use mul_u64_u64_div_u64 to perform the difference calculation in avoid + * possible overflow. + * + * Returns: true if scaled_ppm is negative, false otherwise + */ +static inline bool diff_by_scaled_ppm(u64 base, long scaled_ppm, u64 *diff) +{ + bool negative = false; + + if (scaled_ppm < 0) { + negative = true; + scaled_ppm = -scaled_ppm; + } + + *diff = mul_u64_u64_div_u64(base, (u64)scaled_ppm, 1000000ULL << 16); + + return negative; +} + +/** + * adjust_by_scaled_ppm - Adjust a base increment by scaled parts per million + * @base: the base increment value to adjust + * @scaled_ppm: scaled parts per million frequency adjustment + * + * Helper function which calculates a new increment value based on the + * requested scaled parts per million adjustment. + */ +static inline u64 adjust_by_scaled_ppm(u64 base, long scaled_ppm) +{ + u64 diff; + + if (diff_by_scaled_ppm(base, scaled_ppm, &diff)) + return base - diff; + + return base + diff; +} + #if IS_ENABLED(CONFIG_PTP_1588_CLOCK) /** -- cgit v1.2.3