[Intel-wired-lan] [net-next PATCH 3/7] e1000e: convert .adjfreq to .adjfine

[Jacob Keller]

The PTP implementation for the e1000e driver uses the older .adjfreq
method. This method takes an adjustment in parts per billion. The newer
.adjfine implementation uses scaled_ppm. The use of scaled_ppm allows for
finer grained adjustments and is preferred over using the older
implementation.

Make use of mul_u64_u64_div_u64 in order to handle possible overflow of the
multiplication used to calculate the desired adjustment to the hardware
increment value.

Signed-off-by: Jacob Keller <jacob.e.keller at intel.com>
---
 drivers/net/ethernet/intel/e1000e/e1000.h  |  2 +-
 drivers/net/ethernet/intel/e1000e/netdev.c |  4 ++--
 drivers/net/ethernet/intel/e1000e/ptp.c    | 15 ++++++++-------
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/e1000.h b/drivers/net/ethernet/intel/e1000e/e1000.h
index 8d06c9d8ff8b..e8a9a9610ac6 100644
--- a/drivers/net/ethernet/intel/e1000e/e1000.h
+++ b/drivers/net/ethernet/intel/e1000e/e1000.h
@@ -329,7 +329,7 @@ struct e1000_adapter {
 	struct ptp_clock *ptp_clock;
 	struct ptp_clock_info ptp_clock_info;
 	struct pm_qos_request pm_qos_req;
-	s32 ptp_delta;
+	long ptp_delta;
 
 	u16 eee_advert;
 };
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 70d933f52e93..321f2a95ae3a 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -3922,9 +3922,9 @@ static void e1000e_systim_reset(struct e1000_adapter *adapter)
 	if (!(adapter->flags & FLAG_HAS_HW_TIMESTAMP))
 		return;
 
-	if (info->adjfreq) {
+	if (info->adjfine) {
 		/* restore the previous ptp frequency delta */
-		ret_val = info->adjfreq(info, adapter->ptp_delta);
+		ret_val = info->adjfine(info, adapter->ptp_delta);
 	} else {
 		/* set the default base frequency if no adjustment possible */
 		ret_val = e1000e_get_base_timinca(adapter, &timinca);
diff --git a/drivers/net/ethernet/intel/e1000e/ptp.c b/drivers/net/ethernet/intel/e1000e/ptp.c
index 432e04ce8c4e..0e488e4fa5c1 100644
--- a/drivers/net/ethernet/intel/e1000e/ptp.c
+++ b/drivers/net/ethernet/intel/e1000e/ptp.c
@@ -15,14 +15,16 @@
 #endif
 
 /**
- * e1000e_phc_adjfreq - adjust the frequency of the hardware clock
+ * e1000e_phc_adjfine - adjust the frequency of the hardware clock
  * @ptp: ptp clock structure
- * @delta: Desired frequency change in parts per billion
+ * @delta: Desired frequency chance in scaled parts per million
  *
  * Adjust the frequency of the PHC cycle counter by the indicated delta from
  * the base frequency.
+ *
+ * Scaled parts per million is ppm but with a 16 bit binary fractional field.
  **/
-static int e1000e_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
+static int e1000e_phc_adjfine(struct ptp_clock_info *ptp, long delta)
 {
 	struct e1000_adapter *adapter = container_of(ptp, struct e1000_adapter,
 						     ptp_clock_info);
@@ -47,9 +49,8 @@ static int e1000e_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
 
 	incvalue = timinca & E1000_TIMINCA_INCVALUE_MASK;
 
-	adjustment = incvalue;
-	adjustment *= delta;
-	adjustment = div_u64(adjustment, 1000000000);
+	adjustment = mul_u64_u64_div_u64(incvalue, (u64)delta,
+					 1000000ULL << 16);
 
 	incvalue = neg_adj ? (incvalue - adjustment) : (incvalue + adjustment);
 
@@ -257,7 +258,7 @@ static const struct ptp_clock_info e1000e_ptp_clock_info = {
 	.n_per_out	= 0,
 	.n_pins		= 0,
 	.pps		= 0,
-	.adjfreq	= e1000e_phc_adjfreq,
+	.adjfine	= e1000e_phc_adjfine,
 	.adjtime	= e1000e_phc_adjtime,
 	.gettimex64	= e1000e_phc_gettimex,
 	.settime64	= e1000e_phc_settime,
-- 
2.35.1.456.ga9c7032d4631