igb: Fix SerDes autoneg flow control.

This patch enables flow control to be set in SerDes autoneg mode.  This is
done the way it is done for copper, but relies on a different set of register/bit
checks since this is all done within the MAC registers.
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/e1000_82575.c

@@ -1028,6 +1028,15 @@ static s32 igb_check_for_link_82575(struct e1000_hw *hw)
 		 * continue to check for link.
 		 */
 		hw->mac.get_link_status = !hw->mac.serdes_has_link;
+
+		/* Configure Flow Control now that Auto-Neg has completed.
+		 * First, we need to restore the desired flow control
+		 * settings because we may have had to re-autoneg with a
+		 * different link partner.
+		 */
+		ret_val = igb_config_fc_after_link_up(hw);
+		if (ret_val)
+			hw_dbg("Error configuring flow control\n");
 	} else {
 		ret_val = igb_check_for_copper_link(hw);
 	}
@@ -1345,7 +1354,7 @@ static s32 igb_setup_copper_link_82575(struct e1000_hw *hw)
  **/
 static s32 igb_setup_serdes_link_82575(struct e1000_hw *hw)
 {
-	u32 ctrl_ext, ctrl_reg, reg;
+	u32 ctrl_ext, ctrl_reg, reg, anadv_reg;
 	bool pcs_autoneg;
 	s32 ret_val = E1000_SUCCESS;
 	u16 data;
@@ -1433,27 +1442,45 @@ static s32 igb_setup_serdes_link_82575(struct e1000_hw *hw)
 	reg &= ~(E1000_PCS_LCTL_AN_ENABLE | E1000_PCS_LCTL_FLV_LINK_UP |
 		E1000_PCS_LCTL_FSD | E1000_PCS_LCTL_FORCE_LINK);
 
-	/*
-	 * We force flow control to prevent the CTRL register values from being
-	 * overwritten by the autonegotiated flow control values
-	 */
-	reg |= E1000_PCS_LCTL_FORCE_FCTRL;
-
 	if (pcs_autoneg) {
 		/* Set PCS register for autoneg */
 		reg |= E1000_PCS_LCTL_AN_ENABLE | /* Enable Autoneg */
 		       E1000_PCS_LCTL_AN_RESTART; /* Restart autoneg */
+
+		/* Disable force flow control for autoneg */
+		reg &= ~E1000_PCS_LCTL_FORCE_FCTRL;
+
+		/* Configure flow control advertisement for autoneg */
+		anadv_reg = rd32(E1000_PCS_ANADV);
+		anadv_reg &= ~(E1000_TXCW_ASM_DIR | E1000_TXCW_PAUSE);
+		switch (hw->fc.requested_mode) {
+		case e1000_fc_full:
+		case e1000_fc_rx_pause:
+			anadv_reg |= E1000_TXCW_ASM_DIR;
+			anadv_reg |= E1000_TXCW_PAUSE;
+			break;
+		case e1000_fc_tx_pause:
+			anadv_reg |= E1000_TXCW_ASM_DIR;
+			break;
+		default:
+			break;
+		}
+		wr32(E1000_PCS_ANADV, anadv_reg);
+
 		hw_dbg("Configuring Autoneg:PCS_LCTL=0x%08X\n", reg);
 	} else {
 		/* Set PCS register for forced link */
 		reg |= E1000_PCS_LCTL_FSD;        /* Force Speed */
 
+		/* Force flow control for forced link */
+		reg |= E1000_PCS_LCTL_FORCE_FCTRL;
+
 		hw_dbg("Configuring Forced Link:PCS_LCTL=0x%08X\n", reg);
 	}
 
 	wr32(E1000_PCS_LCTL, reg);
 
-	if (!igb_sgmii_active_82575(hw))
+	if (!pcs_autoneg && !igb_sgmii_active_82575(hw))
 		igb_force_mac_fc(hw);
 
 	return ret_val;

drivers/net/ethernet/intel/igb/e1000_defines.h

@@ -431,6 +431,10 @@
 #define FLOW_CONTROL_ADDRESS_HIGH 0x00000100
 #define FLOW_CONTROL_TYPE         0x8808
 
+/* Transmit Config Word */
+#define E1000_TXCW_ASM_DIR	0x00000100 /* TXCW astm pause direction */
+#define E1000_TXCW_PAUSE	0x00000080 /* TXCW sym pause request */
+
 /* 802.1q VLAN Packet Size */
 #define VLAN_TAG_SIZE              4    /* 802.3ac tag (not DMA'd) */
 #define E1000_VLAN_FILTER_TBL_SIZE 128  /* VLAN Filter Table (4096 bits) */
@@ -539,6 +543,9 @@
 /* mPHY Near End Digital Loopback Override Bit */
 #define E1000_MPHY_PCS_CLK_REG_DIGINELBEN 0x10
 
+#define E1000_PCS_LCTL_FORCE_FCTRL	0x80
+#define E1000_PCS_LSTS_AN_COMPLETE	0x10000
+
 /* PHY Control Register */
 #define MII_CR_FULL_DUPLEX      0x0100  /* FDX =1, half duplex =0 */
 #define MII_CR_RESTART_AUTO_NEG 0x0200  /* Restart auto negotiation */

drivers/net/ethernet/intel/igb/e1000_mac.c

@@ -839,6 +839,7 @@ s32 igb_config_fc_after_link_up(struct e1000_hw *hw)
 {
 	struct e1000_mac_info *mac = &hw->mac;
 	s32 ret_val = 0;
+	u32 pcs_status_reg, pcs_adv_reg, pcs_lp_ability_reg, pcs_ctrl_reg;
 	u16 mii_status_reg, mii_nway_adv_reg, mii_nway_lp_ability_reg;
 	u16 speed, duplex;
 
@@ -1040,6 +1041,129 @@ s32 igb_config_fc_after_link_up(struct e1000_hw *hw)
 			goto out;
 		}
 	}
+	/* Check for the case where we have SerDes media and auto-neg is
+	 * enabled.  In this case, we need to check and see if Auto-Neg
+	 * has completed, and if so, how the PHY and link partner has
+	 * flow control configured.
+	 */
+	if ((hw->phy.media_type == e1000_media_type_internal_serdes)
+		&& mac->autoneg) {
+		/* Read the PCS_LSTS and check to see if AutoNeg
+		 * has completed.
+		 */
+		pcs_status_reg = rd32(E1000_PCS_LSTAT);
+
+		if (!(pcs_status_reg & E1000_PCS_LSTS_AN_COMPLETE)) {
+			hw_dbg("PCS Auto Neg has not completed.\n");
+			return ret_val;
+		}
+
+		/* The AutoNeg process has completed, so we now need to
+		 * read both the Auto Negotiation Advertisement
+		 * Register (PCS_ANADV) and the Auto_Negotiation Base
+		 * Page Ability Register (PCS_LPAB) to determine how
+		 * flow control was negotiated.
+		 */
+		pcs_adv_reg = rd32(E1000_PCS_ANADV);
+		pcs_lp_ability_reg = rd32(E1000_PCS_LPAB);
+
+		/* Two bits in the Auto Negotiation Advertisement Register
+		 * (PCS_ANADV) and two bits in the Auto Negotiation Base
+		 * Page Ability Register (PCS_LPAB) determine flow control
+		 * for both the PHY and the link partner.  The following
+		 * table, taken out of the IEEE 802.3ab/D6.0 dated March 25,
+		 * 1999, describes these PAUSE resolution bits and how flow
+		 * control is determined based upon these settings.
+		 * NOTE:  DC = Don't Care
+		 *
+		 *   LOCAL DEVICE  |   LINK PARTNER
+		 * PAUSE | ASM_DIR | PAUSE | ASM_DIR | NIC Resolution
+		 *-------|---------|-------|---------|--------------------
+		 *   0   |    0    |  DC   |   DC    | e1000_fc_none
+		 *   0   |    1    |   0   |   DC    | e1000_fc_none
+		 *   0   |    1    |   1   |    0    | e1000_fc_none
+		 *   0   |    1    |   1   |    1    | e1000_fc_tx_pause
+		 *   1   |    0    |   0   |   DC    | e1000_fc_none
+		 *   1   |   DC    |   1   |   DC    | e1000_fc_full
+		 *   1   |    1    |   0   |    0    | e1000_fc_none
+		 *   1   |    1    |   0   |    1    | e1000_fc_rx_pause
+		 *
+		 * Are both PAUSE bits set to 1?  If so, this implies
+		 * Symmetric Flow Control is enabled at both ends.  The
+		 * ASM_DIR bits are irrelevant per the spec.
+		 *
+		 * For Symmetric Flow Control:
+		 *
+		 *   LOCAL DEVICE  |   LINK PARTNER
+		 * PAUSE | ASM_DIR | PAUSE | ASM_DIR | Result
+		 *-------|---------|-------|---------|--------------------
+		 *   1   |   DC    |   1   |   DC    | e1000_fc_full
+		 *
+		 */
+		if ((pcs_adv_reg & E1000_TXCW_PAUSE) &&
+		    (pcs_lp_ability_reg & E1000_TXCW_PAUSE)) {
+			/* Now we need to check if the user selected Rx ONLY
+			 * of pause frames.  In this case, we had to advertise
+			 * FULL flow control because we could not advertise Rx
+			 * ONLY. Hence, we must now check to see if we need to
+			 * turn OFF the TRANSMISSION of PAUSE frames.
+			 */
+			if (hw->fc.requested_mode == e1000_fc_full) {
+				hw->fc.current_mode = e1000_fc_full;
+				hw_dbg("Flow Control = FULL.\n");
+			} else {
+				hw->fc.current_mode = e1000_fc_rx_pause;
+				hw_dbg("Flow Control = Rx PAUSE frames only.\n");
+			}
+		}
+		/* For receiving PAUSE frames ONLY.
+		 *
+		 *   LOCAL DEVICE  |   LINK PARTNER
+		 * PAUSE | ASM_DIR | PAUSE | ASM_DIR | Result
+		 *-------|---------|-------|---------|--------------------
+		 *   0   |    1    |   1   |    1    | e1000_fc_tx_pause
+		 */
+		else if (!(pcs_adv_reg & E1000_TXCW_PAUSE) &&
+			  (pcs_adv_reg & E1000_TXCW_ASM_DIR) &&
+			  (pcs_lp_ability_reg & E1000_TXCW_PAUSE) &&
+			  (pcs_lp_ability_reg & E1000_TXCW_ASM_DIR)) {
+			hw->fc.current_mode = e1000_fc_tx_pause;
+			hw_dbg("Flow Control = Tx PAUSE frames only.\n");
+		}
+		/* For transmitting PAUSE frames ONLY.
+		 *
+		 *   LOCAL DEVICE  |   LINK PARTNER
+		 * PAUSE | ASM_DIR | PAUSE | ASM_DIR | Result
+		 *-------|---------|-------|---------|--------------------
+		 *   1   |    1    |   0   |    1    | e1000_fc_rx_pause
+		 */
+		else if ((pcs_adv_reg & E1000_TXCW_PAUSE) &&
+			 (pcs_adv_reg & E1000_TXCW_ASM_DIR) &&
+			 !(pcs_lp_ability_reg & E1000_TXCW_PAUSE) &&
+			 (pcs_lp_ability_reg & E1000_TXCW_ASM_DIR)) {
+			hw->fc.current_mode = e1000_fc_rx_pause;
+			hw_dbg("Flow Control = Rx PAUSE frames only.\n");
+		} else {
+			/* Per the IEEE spec, at this point flow control
+			 * should be disabled.
+			 */
+			hw->fc.current_mode = e1000_fc_none;
+			hw_dbg("Flow Control = NONE.\n");
+		}
+
+		/* Now we call a subroutine to actually force the MAC
+		 * controller to use the correct flow control settings.
+		 */
+		pcs_ctrl_reg = rd32(E1000_PCS_LCTL);
+		pcs_ctrl_reg |= E1000_PCS_LCTL_FORCE_FCTRL;
+		wr32(E1000_PCS_LCTL, pcs_ctrl_reg);
+
+		ret_val = igb_force_mac_fc(hw);
+		if (ret_val) {
+			hw_dbg("Error forcing flow control settings\n");
+			return ret_val;
+		}
+	}
 
 out:
 	return ret_val;