e1000e: i219 fix unit hang on reset and runtime D3

Unit hang may occur if multiple descriptors are available in the rings
during reset or runtime suspend. This state can be detected by testing
bit 8 in the FEXTNVM7 register. If this bit is set and there are pending
descriptors in one of the rings, we must flush them prior to reset. Same
applies entering runtime suspend.

Signed-off-by: Yanir Lubetkin <yanirx.lubetkin@intel.com>
Reviewed-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -100,6 +100,11 @@
 #define E1000_FEXTNVM7_DISABLE_PB_READ	0x00040000
 
 #define E1000_FEXTNVM7_DISABLE_SMB_PERST	0x00000020
+#define E1000_FEXTNVM7_NEED_DESCRING_FLUSH	0x00000100
+#define E1000_FEXTNVM11_DISABLE_MULR_FIX	0x00002000
+
+/* bit24: RXDCTL thresholds granularity: 0 - cache lines, 1 - descriptors */
+#define E1000_RXDCTL_THRESH_UNIT_DESC 0x01000000
 
 #define K1_ENTRY_LATENCY	0
 #define K1_MIN_TIME		1

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

@@ -3787,6 +3787,106 @@ static void e1000_power_down_phy(struct e1000_adapter *adapter)
 		adapter->hw.phy.ops.power_down(&adapter->hw);
 }
 
+/**
+ * e1000_flush_tx_ring - remove all descriptors from the tx_ring
+ *
+ * We want to clear all pending descriptors from the TX ring.
+ * zeroing happens when the HW reads the regs. We  assign the ring itself as
+ * the data of the next descriptor. We don't care about the data we are about
+ * to reset the HW.
+ */
+static void e1000_flush_tx_ring(struct e1000_adapter *adapter)
+{
+	struct e1000_hw *hw = &adapter->hw;
+	struct e1000_ring *tx_ring = adapter->tx_ring;
+	struct e1000_tx_desc *tx_desc = NULL;
+	u32 tdt, tctl, txd_lower = E1000_TXD_CMD_IFCS;
+	u16 size = 512;
+
+	tctl = er32(TCTL);
+	ew32(TCTL, tctl | E1000_TCTL_EN);
+	tdt = er32(TDT(0));
+	BUG_ON(tdt != tx_ring->next_to_use);
+	tx_desc =  E1000_TX_DESC(*tx_ring, tx_ring->next_to_use);
+	tx_desc->buffer_addr = tx_ring->dma;
+
+	tx_desc->lower.data = cpu_to_le32(txd_lower | size);
+	tx_desc->upper.data = 0;
+	/* flush descriptors to memory before notifying the HW */
+	wmb();
+	tx_ring->next_to_use++;
+	if (tx_ring->next_to_use == tx_ring->count)
+		tx_ring->next_to_use = 0;
+	ew32(TDT(0), tx_ring->next_to_use);
+	mmiowb();
+	usleep_range(200, 250);
+}
+
+/**
+ * e1000_flush_rx_ring - remove all descriptors from the rx_ring
+ *
+ * Mark all descriptors in the RX ring as consumed and disable the rx ring
+ */
+static void e1000_flush_rx_ring(struct e1000_adapter *adapter)
+{
+	u32 rctl, rxdctl;
+	struct e1000_hw *hw = &adapter->hw;
+
+	rctl = er32(RCTL);
+	ew32(RCTL, rctl & ~E1000_RCTL_EN);
+	e1e_flush();
+	usleep_range(100, 150);
+
+	rxdctl = er32(RXDCTL(0));
+	/* zero the lower 14 bits (prefetch and host thresholds) */
+	rxdctl &= 0xffffc000;
+
+	/* update thresholds: prefetch threshold to 31, host threshold to 1
+	 * and make sure the granularity is "descriptors" and not "cache lines"
+	 */
+	rxdctl |= (0x1F | (1 << 8) | E1000_RXDCTL_THRESH_UNIT_DESC);
+
+	ew32(RXDCTL(0), rxdctl);
+	/* momentarily enable the RX ring for the changes to take effect */
+	ew32(RCTL, rctl | E1000_RCTL_EN);
+	e1e_flush();
+	usleep_range(100, 150);
+	ew32(RCTL, rctl & ~E1000_RCTL_EN);
+}
+
+/**
+ * e1000_flush_desc_rings - remove all descriptors from the descriptor rings
+ *
+ * In i219, the descriptor rings must be emptied before resetting the HW
+ * or before changing the device state to D3 during runtime (runtime PM).
+ *
+ * Failure to do this will cause the HW to enter a unit hang state which can
+ * only be released by PCI reset on the device
+ *
+ */
+
+static void e1000_flush_desc_rings(struct e1000_adapter *adapter)
+{
+	u32 hang_state;
+	u32 fext_nvm11, tdlen;
+	struct e1000_hw *hw = &adapter->hw;
+
+	/* First, disable MULR fix in FEXTNVM11 */
+	fext_nvm11 = er32(FEXTNVM11);
+	fext_nvm11 |= E1000_FEXTNVM11_DISABLE_MULR_FIX;
+	ew32(FEXTNVM11, fext_nvm11);
+	/* do nothing if we're not in faulty state, or if the queue is empty */
+	tdlen = er32(TDLEN(0));
+	hang_state = er32(FEXTNVM7);
+	if ((hang_state & E1000_FEXTNVM7_NEED_DESCRING_FLUSH) || tdlen)
+		return;
+	e1000_flush_tx_ring(adapter);
+	/* recheck, maybe the fault is caused by the rx ring */
+	hang_state = er32(FEXTNVM7);
+	if (hang_state & E1000_FEXTNVM7_NEED_DESCRING_FLUSH)
+		e1000_flush_rx_ring(adapter);
+}
+
 /**
  * e1000e_reset - bring the hardware into a known good state
  *
@@ -4115,6 +4215,8 @@ void e1000e_down(struct e1000_adapter *adapter, bool reset)
 	spin_unlock(&adapter->stats64_lock);
 
 	e1000e_flush_descriptors(adapter);
+	if (hw->mac.type == e1000_pch_spt)
+		e1000_flush_desc_rings(adapter);
 	e1000_clean_tx_ring(adapter->tx_ring);
 	e1000_clean_rx_ring(adapter->rx_ring);
 

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

@@ -38,6 +38,7 @@
 #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_FEXTNVM11	0x5BBC  /* Future Extended NVM 11 - RW */
 #define E1000_PCIEANACFG	0x00F18	/* PCIE Analog Config */
 #define E1000_FCT	0x00030	/* Flow Control Type - RW */
 #define E1000_VET	0x00038	/* VLAN Ether Type - RW */