From: Jacob Keller <jacob.e.keller@intel.com>
Date: Thu, 21 Jul 2022 14:30:01 -0700
Subject: igb: convert .adjfreq to .adjfine
Patch-mainline: v6.0-rc1
Git-commit: d8fae2504efee73958cbbf9c7122f13f95495222
References: jsc#PED-370

The 82576 PTP implementation still uses .adjfreq instead of using the newer
.adjfine.

This implementation uses a pre-simplified calculation since the base
increment value for the 82576 is just 16 * 2^19. Converting this into
scaled_ppm is tricky, and makes the intent a bit less clear.

Simply convert to the normal flow of multiplying the base increment value
by the scaled_ppm and then dividing by 1000000ULL << 16. This can be
implemented using mul_u64_u64_div_u64 which can avoid the possible overflow
that might occur for large adjustments.

Use of .adjfine can improve the precision of small adjustments and gets us
one driver closer to removing the old implementation from the kernel
entirely.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/intel/igb/igb_ptp.c |   15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

--- a/drivers/net/ethernet/intel/igb/igb_ptp.c
+++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
@@ -190,7 +190,7 @@ static void igb_ptp_systim_to_hwtstamp(s
 }
 
 /* PTP clock operations */
-static int igb_ptp_adjfreq_82576(struct ptp_clock_info *ptp, s32 ppb)
+static int igb_ptp_adjfine_82576(struct ptp_clock_info *ptp, long scaled_ppm)
 {
 	struct igb_adapter *igb = container_of(ptp, struct igb_adapter,
 					       ptp_caps);
@@ -199,15 +199,14 @@ static int igb_ptp_adjfreq_82576(struct
 	u64 rate;
 	u32 incvalue;
 
-	if (ppb < 0) {
+	if (scaled_ppm < 0) {
 		neg_adj = 1;
-		ppb = -ppb;
+		scaled_ppm = -scaled_ppm;
 	}
-	rate = ppb;
-	rate <<= 14;
-	rate = div_u64(rate, 1953125);
 
-	incvalue = 16 << IGB_82576_TSYNC_SHIFT;
+	incvalue = INCVALUE_82576;
+	rate = mul_u64_u64_div_u64(incvalue, (u64)scaled_ppm,
+				   1000000ULL << 16);
 
 	if (neg_adj)
 		incvalue -= rate;
@@ -1351,7 +1350,7 @@ void igb_ptp_init(struct igb_adapter *ad
 		adapter->ptp_caps.max_adj = 999999881;
 		adapter->ptp_caps.n_ext_ts = 0;
 		adapter->ptp_caps.pps = 0;
-		adapter->ptp_caps.adjfreq = igb_ptp_adjfreq_82576;
+		adapter->ptp_caps.adjfine = igb_ptp_adjfine_82576;
 		adapter->ptp_caps.adjtime = igb_ptp_adjtime_82576;
 		adapter->ptp_caps.gettimex64 = igb_ptp_gettimex_82576;
 		adapter->ptp_caps.settime64 = igb_ptp_settime_82576;