e1000e: PTP lock in e1000e_phc_adjustfreq

Add lock in e1000e_phc_adjfreq to prevent concurrent changes to TIMINCA
and SYSTIMH/L.

Signed-off-by: Todd Fujinaka <todd.fujinaka@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/ptp.c

@@ -47,6 +47,7 @@ static int e1000e_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
 						     ptp_clock_info);
 	struct e1000_hw *hw = &adapter->hw;
 	bool neg_adj = false;
+	unsigned long flags;
 	u64 adjustment;
 	u32 timinca, incvalue;
 	s32 ret_val;
@@ -64,6 +65,8 @@ static int e1000e_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
 	if (ret_val)
 		return ret_val;
 
+	spin_lock_irqsave(&adapter->systim_lock, flags);
+
 	incvalue = timinca & E1000_TIMINCA_INCVALUE_MASK;
 
 	adjustment = incvalue;
@@ -77,6 +80,8 @@ static int e1000e_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
 
 	ew32(TIMINCA, timinca);
 
+	spin_unlock_irqrestore(&adapter->systim_lock, flags);
+
 	return 0;
 }