e1000e: workaround DMA unit hang on I218

At 1000Mbps link speed, one of the MAC's internal clocks can be stopped for
up to 4us when entering K1 (a power mode of the MAC-PHY interconnect).  If
the MAC is waiting for completion indications for 2 DMA write requests into
Host memory (e.g. descriptor writeback or Rx packet writing) and the
indications occur while the clock is stopped, both indications will be
missed by the MAC causing the MAC to wait for the completion indications
and be unable to generate further DMA write requests.  This results in an
apparent hardware hang.

Work-around the issue by disabling the de-assertion of the clock request
when 1000Mbps link is acquired (K1 must be disabled while doing this).

Signed-off-by: Bruce Allan <bruce.w.allan@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/ich8lan.c

@@ -781,6 +781,59 @@ release:
 	return ret_val;
 }
 
+/**
+ *  e1000_k1_workaround_lpt_lp - K1 workaround on Lynxpoint-LP
+ *  @hw:   pointer to the HW structure
+ *  @link: link up bool flag
+ *
+ *  When K1 is enabled for 1Gbps, the MAC can miss 2 DMA completion indications
+ *  preventing further DMA write requests.  Workaround the issue by disabling
+ *  the de-assertion of the clock request when in 1Gpbs mode.
+ **/
+static s32 e1000_k1_workaround_lpt_lp(struct e1000_hw *hw, bool link)
+{
+	u32 fextnvm6 = er32(FEXTNVM6);
+	s32 ret_val = 0;
+
+	if (link && (er32(STATUS) & E1000_STATUS_SPEED_1000)) {
+		u16 kmrn_reg;
+
+		ret_val = hw->phy.ops.acquire(hw);
+		if (ret_val)
+			return ret_val;
+
+		ret_val =
+		    e1000e_read_kmrn_reg_locked(hw, E1000_KMRNCTRLSTA_K1_CONFIG,
+						&kmrn_reg);
+		if (ret_val)
+			goto release;
+
+		ret_val =
+		    e1000e_write_kmrn_reg_locked(hw,
+						 E1000_KMRNCTRLSTA_K1_CONFIG,
+						 kmrn_reg &
+						 ~E1000_KMRNCTRLSTA_K1_ENABLE);
+		if (ret_val)
+			goto release;
+
+		usleep_range(10, 20);
+
+		ew32(FEXTNVM6, fextnvm6 | E1000_FEXTNVM6_REQ_PLL_CLK);
+
+		ret_val =
+		    e1000e_write_kmrn_reg_locked(hw,
+						 E1000_KMRNCTRLSTA_K1_CONFIG,
+						 kmrn_reg);
+release:
+		hw->phy.ops.release(hw);
+	} else {
+		/* clear FEXTNVM6 bit 8 on link down or 10/100 */
+		ew32(FEXTNVM6, fextnvm6 & ~E1000_FEXTNVM6_REQ_PLL_CLK);
+	}
+
+	return ret_val;
+}
+
 /**
  *  e1000_check_for_copper_link_ich8lan - Check for link (Copper)
  *  @hw: pointer to the HW structure
@@ -818,6 +871,14 @@ static s32 e1000_check_for_copper_link_ich8lan(struct e1000_hw *hw)
 			return ret_val;
 	}
 
+	/* Work-around I218 hang issue */
+	if ((hw->adapter->pdev->device == E1000_DEV_ID_PCH_LPTLP_I218_LM) ||
+	    (hw->adapter->pdev->device == E1000_DEV_ID_PCH_LPTLP_I218_V)) {
+		ret_val = e1000_k1_workaround_lpt_lp(hw, link);
+		if (ret_val)
+			return ret_val;
+	}
+
 	/* Clear link partner's EEE ability */
 	hw->dev_spec.ich8lan.eee_lp_ability = 0;
 
@@ -3954,8 +4015,16 @@ void e1000_suspend_workarounds_ich8lan(struct e1000_hw *hw)
 
 	phy_ctrl = er32(PHY_CTRL);
 	phy_ctrl |= E1000_PHY_CTRL_GBE_DISABLE;
+
 	if (hw->phy.type == e1000_phy_i217) {
-		u16 phy_reg;
+		u16 phy_reg, device_id = hw->adapter->pdev->device;
+
+		if ((device_id == E1000_DEV_ID_PCH_LPTLP_I218_LM) ||
+		    (device_id == E1000_DEV_ID_PCH_LPTLP_I218_V)) {
+			u32 fextnvm6 = er32(FEXTNVM6);
+
+			ew32(FEXTNVM6, fextnvm6 & ~E1000_FEXTNVM6_REQ_PLL_CLK);
+		}
 
 		ret_val = hw->phy.ops.acquire(hw);
 		if (ret_val)

drivers/net/ethernet/intel/e1000e/ich8lan.h

@@ -92,6 +92,8 @@
 #define E1000_FEXTNVM4_BEACON_DURATION_8USEC	0x7
 #define E1000_FEXTNVM4_BEACON_DURATION_16USEC	0x3
 
+#define E1000_FEXTNVM6_REQ_PLL_CLK	0x00000100
+
 #define PCIE_ICH8_SNOOP_ALL	PCIE_NO_SNOOP_ALL
 
 #define E1000_ICH_RAR_ENTRIES	7

drivers/net/ethernet/intel/e1000e/regs.h

@@ -42,6 +42,7 @@
 #define E1000_FEXTNVM	0x00028	/* Future Extended NVM - RW */
 #define E1000_FEXTNVM3	0x0003C	/* Future Extended NVM 3 - RW */
 #define E1000_FEXTNVM4	0x00024	/* Future Extended NVM 4 - RW */
+#define E1000_FEXTNVM6	0x00010	/* Future Extended NVM 6 - RW */
 #define E1000_FEXTNVM7	0x000E4	/* Future Extended NVM 7 - RW */
 #define E1000_FCT	0x00030	/* Flow Control Type - RW */
 #define E1000_VET	0x00038	/* VLAN Ether Type - RW */