ixgbe: Add work around for empty SFP+ cage crosstalk

It is possible on some systems that crosstalk could lead to link flap
on empty SFP+ cages.  A new NVM bit was defined to let SW know it
needs to implement the work around which consists of verifying that
there is a module in the cage before acting on the LSC.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe.h

@@ -803,6 +803,8 @@ struct ixgbe_adapter {
 
 #define IXGBE_RSS_KEY_SIZE     40  /* size of RSS Hash Key in bytes */
 	u32 rss_key[IXGBE_RSS_KEY_SIZE / sizeof(u32)];
+
+	bool need_crosstalk_fix;
 };
 
 static inline u8 ixgbe_max_rss_indices(struct ixgbe_adapter *adapter)

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -5572,6 +5572,7 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter)
 	struct pci_dev *pdev = adapter->pdev;
 	unsigned int rss, fdir;
 	u32 fwsm;
+	u16 device_caps;
 #ifdef CONFIG_IXGBE_DCB
 	int j;
 	struct tc_configuration *tc;
@@ -5737,6 +5738,22 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter)
 	adapter->tx_ring_count = IXGBE_DEFAULT_TXD;
 	adapter->rx_ring_count = IXGBE_DEFAULT_RXD;
 
+	/* Cache bit indicating need for crosstalk fix */
+	switch (hw->mac.type) {
+	case ixgbe_mac_82599EB:
+	case ixgbe_mac_X550EM_x:
+	case ixgbe_mac_x550em_a:
+		hw->mac.ops.get_device_caps(hw, &device_caps);
+		if (device_caps & IXGBE_DEVICE_CAPS_NO_CROSSTALK_WR)
+			adapter->need_crosstalk_fix = false;
+		else
+			adapter->need_crosstalk_fix = true;
+		break;
+	default:
+		adapter->need_crosstalk_fix = false;
+		break;
+	}
+
 	/* set default work limits */
 	adapter->tx_work_limit = IXGBE_DEFAULT_TX_WORK;
 
@@ -6659,6 +6676,18 @@ static void ixgbe_watchdog_update_link(struct ixgbe_adapter *adapter)
 		link_up = true;
 	}
 
+	/* If Crosstalk fix enabled do the sanity check of making sure
+	 * the SFP+ cage is empty.
+	 */
+	if (adapter->need_crosstalk_fix) {
+		u32 sfp_cage_full;
+
+		sfp_cage_full = IXGBE_READ_REG(hw, IXGBE_ESDP) &
+				IXGBE_ESDP_SDP2;
+		if (ixgbe_is_sfp(hw) && link_up && !sfp_cage_full)
+			link_up = false;
+	}
+
 	if (adapter->ixgbe_ieee_pfc)
 		pfc_en |= !!(adapter->ixgbe_ieee_pfc->pfc_en);
 
@@ -7005,6 +7034,16 @@ static void ixgbe_sfp_detection_subtask(struct ixgbe_adapter *adapter)
 	struct ixgbe_hw *hw = &adapter->hw;
 	s32 err;
 
+	/* If crosstalk fix enabled verify the SFP+ cage is full */
+	if (adapter->need_crosstalk_fix) {
+		u32 sfp_cage_full;
+
+		sfp_cage_full = IXGBE_READ_REG(hw, IXGBE_ESDP) &
+				IXGBE_ESDP_SDP2;
+		if (!sfp_cage_full)
+			return;
+	}
+
 	/* not searching for SFP so there is nothing to do here */
 	if (!(adapter->flags2 & IXGBE_FLAG2_SEARCH_FOR_SFP) &&
 	    !(adapter->flags2 & IXGBE_FLAG2_SFP_NEEDS_RESET))

drivers/net/ethernet/intel/ixgbe/ixgbe_type.h

@@ -2124,6 +2124,7 @@ enum {
 #define IXGBE_SAN_MAC_ADDR_PORT1_OFFSET  0x3
 #define IXGBE_DEVICE_CAPS_ALLOW_ANY_SFP  0x1
 #define IXGBE_DEVICE_CAPS_FCOE_OFFLOADS  0x2
+#define IXGBE_DEVICE_CAPS_NO_CROSSTALK_WR	BIT(7)
 #define IXGBE_FW_LESM_PARAMETERS_PTR     0x2
 #define IXGBE_FW_LESM_STATE_1            0x1
 #define IXGBE_FW_LESM_STATE_ENABLED      0x8000 /* LESM Enable bit */