netdev - [PATCH net-next 5/7] i40e: convert .adjfreq to .adjfine

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Date:   Thu, 28 Jul 2022 11:18:34 -0700
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com
Cc:     Jacob Keller <jacob.e.keller@...el.com>, netdev@...r.kernel.org,
        anthony.l.nguyen@...el.com, richardcochran@...il.com,
        Gurucharan <gurucharanx.g@...el.com>
Subject: [PATCH net-next 5/7] i40e: convert .adjfreq to .adjfine

From: Jacob Keller <jacob.e.keller@...el.com>

The i40e driver currently implements the .adjfreq handler for frequency
adjustments. This takes the adjustment parameter in parts per billion. The
PTP core supports .adjfine which provides an adjustment in scaled parts per
million. This has a higher resolution and can result in more precise
adjustments for small corrections.

Convert the existing .adjfreq implementation to the newer .adjfine
implementation. This is trivial since it just requires changing the divisor
from 1000000000ULL to (1000000ULL << 16) in the mul_u64_u64_div_u64 call.

This improves the precision of the adjustments and gets us one driver
closer to removing the old .adjfreq support from the kernel.

Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
Tested-by: Gurucharan <gurucharanx.g@...el.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/i40e/i40e_ptp.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_ptp.c b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
index 15de918abc41..2d3533f38d7b 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ptp.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ptp.c
@@ -334,29 +334,31 @@ static void i40e_ptp_convert_to_hwtstamp(struct skb_shared_hwtstamps *hwtstamps,
 }
 
 /**
- * i40e_ptp_adjfreq - Adjust the PHC frequency
+ * i40e_ptp_adjfine - Adjust the PHC frequency
  * @ptp: The PTP clock structure
- * @ppb: Parts per billion adjustment from the base
+ * @scaled_ppm: Scaled parts per million adjustment from base
  *
- * Adjust the frequency of the PHC by the indicated parts per billion from the
- * base frequency.
+ * Adjust the frequency of the PHC by the indicated delta from the base
+ * frequency.
+ *
+ * Scaled parts per million is ppm with a 16 bit binary fractional field.
  **/
-static int i40e_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
+static int i40e_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
 {
 	struct i40e_pf *pf = container_of(ptp, struct i40e_pf, ptp_caps);
 	struct i40e_hw *hw = &pf->hw;
 	u64 adj, freq, diff;
 	int neg_adj = 0;
 
-	if (ppb < 0) {
+	if (scaled_ppm < 0) {
 		neg_adj = 1;
-		ppb = -ppb;
+		scaled_ppm = -scaled_ppm;
 	}
 
 	smp_mb(); /* Force any pending update before accessing. */
 	freq = I40E_PTP_40GB_INCVAL * READ_ONCE(pf->ptp_adj_mult);
-	diff = mul_u64_u64_div_u64(freq, (u64)ppb,
-				   1000000000ULL);
+	diff = mul_u64_u64_div_u64(freq, (u64)scaled_ppm,
+				   1000000ULL << 16);
 
 	if (neg_adj)
 		adj = I40E_PTP_40GB_INCVAL - diff;
@@ -1392,7 +1394,7 @@ static long i40e_ptp_create_clock(struct i40e_pf *pf)
 		sizeof(pf->ptp_caps.name) - 1);
 	pf->ptp_caps.owner = THIS_MODULE;
 	pf->ptp_caps.max_adj = 999999999;
-	pf->ptp_caps.adjfreq = i40e_ptp_adjfreq;
+	pf->ptp_caps.adjfine = i40e_ptp_adjfine;
 	pf->ptp_caps.adjtime = i40e_ptp_adjtime;
 	pf->ptp_caps.gettimex64 = i40e_ptp_gettimex;
 	pf->ptp_caps.settime64 = i40e_ptp_settime;
-- 
2.35.1