e1000e: 82574/82583 TimeSync errata for SYSTIM read
Due to a synchronization error, the value read from SYSTIML/SYSTIMH
might be incorrect.
Signed-off-by: Todd Fujinaka <todd.fujinaka@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 6084e6b..95cf482 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -4099,12 +4099,37 @@
struct e1000_adapter *adapter = container_of(cc, struct e1000_adapter,
cc);
struct e1000_hw *hw = &adapter->hw;
- cycle_t systim;
+ cycle_t systim, systim_next;
/* latch SYSTIMH on read of SYSTIML */
systim = (cycle_t)er32(SYSTIML);
systim |= (cycle_t)er32(SYSTIMH) << 32;
+ if ((hw->mac.type == e1000_82574) || (hw->mac.type == e1000_82583)) {
+ u64 incvalue, time_delta, rem, temp;
+ int i;
+
+ /* errata for 82574/82583 possible bad bits read from SYSTIMH/L
+ * check to see that the time is incrementing at a reasonable
+ * rate and is a multiple of incvalue
+ */
+ incvalue = er32(TIMINCA) & E1000_TIMINCA_INCVALUE_MASK;
+ for (i = 0; i < E1000_MAX_82574_SYSTIM_REREADS; i++) {
+ /* latch SYSTIMH on read of SYSTIML */
+ systim_next = (cycle_t)er32(SYSTIML);
+ systim_next |= (cycle_t)er32(SYSTIMH) << 32;
+
+ time_delta = systim_next - systim;
+ temp = time_delta;
+ rem = do_div(temp, incvalue);
+
+ systim = systim_next;
+
+ if ((time_delta < E1000_82574_SYSTIM_EPSILON) &&
+ (rem == 0))
+ break;
+ }
+ }
return systim;
}