net: stmmac: Get correct timestamp values from XGMAC

TX Timestamp in XGMAC comes from MAC instead of descriptors. Implement
this in a new callback.

Also, RX Timestamp in XGMAC must be cheked against corruption and we need
a barrier to make sure that descriptor fields are read correctly.

Changes from v2:
	- Rework return code check (Jakub)
Changes from v1:
	- Rework the get timestamp function (David)

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c

@@ -997,6 +997,20 @@ static int dwxgmac3_rxp_config(void __iomem *ioaddr,
 	return ret;
 }
 
+static int dwxgmac2_get_mac_tx_timestamp(struct mac_device_info *hw, u64 *ts)
+{
+	void __iomem *ioaddr = hw->pcsr;
+	u32 value;
+
+	if (readl_poll_timeout_atomic(ioaddr + XGMAC_TIMESTAMP_STATUS,
+				      value, value & XGMAC_TXTSC, 100, 10000))
+		return -EBUSY;
+
+	*ts = readl(ioaddr + XGMAC_TXTIMESTAMP_NSEC) & XGMAC_TXTSSTSLO;
+	*ts += readl(ioaddr + XGMAC_TXTIMESTAMP_SEC) * 1000000000ULL;
+	return 0;
+}
+
 const struct stmmac_ops dwxgmac210_ops = {
 	.core_init = dwxgmac2_core_init,
 	.set_mac = dwxgmac2_set_mac,
@@ -1033,6 +1047,7 @@ const struct stmmac_ops dwxgmac210_ops = {
 	.rss_configure = dwxgmac2_rss_configure,
 	.update_vlan_hash = dwxgmac2_update_vlan_hash,
 	.rxp_config = dwxgmac3_rxp_config,
+	.get_mac_tx_timestamp = dwxgmac2_get_mac_tx_timestamp,
 };
 
 int dwxgmac2_setup(struct stmmac_priv *priv)

drivers/net/ethernet/stmicro/stmmac/dwxgmac2_descs.c

@@ -98,11 +98,17 @@ static int dwxgmac2_rx_check_timestamp(void *desc)
 	unsigned int rdes3 = le32_to_cpu(p->des3);
 	bool desc_valid, ts_valid;
 
+	dma_rmb();
+
 	desc_valid = !(rdes3 & XGMAC_RDES3_OWN) && (rdes3 & XGMAC_RDES3_CTXT);
 	ts_valid = !(rdes3 & XGMAC_RDES3_TSD) && (rdes3 & XGMAC_RDES3_TSA);
 
-	if (likely(desc_valid && ts_valid))
+	if (likely(desc_valid && ts_valid)) {
+		if ((p->des0 == 0xffffffff) && (p->des1 == 0xffffffff))
+			return -EINVAL;
 		return 0;
+	}
+
 	return -EINVAL;
 }
 
@@ -113,13 +119,10 @@ static int dwxgmac2_get_rx_timestamp_status(void *desc, void *next_desc,
 	unsigned int rdes3 = le32_to_cpu(p->des3);
 	int ret = -EBUSY;
 
-	if (likely(rdes3 & XGMAC_RDES3_CDA)) {
+	if (likely(rdes3 & XGMAC_RDES3_CDA))
 		ret = dwxgmac2_rx_check_timestamp(next_desc);
-		if (ret)
-			return ret;
-	}
 
-	return ret;
+	return !ret;
 }
 
 static void dwxgmac2_init_rx_desc(struct dma_desc *p, int disable_rx_ic,

drivers/net/ethernet/stmicro/stmmac/hwif.h

@@ -339,6 +339,8 @@ struct stmmac_ops {
 	/* VLAN */
 	void (*update_vlan_hash)(struct mac_device_info *hw, u32 hash,
 				 bool is_double);
+	/* TX Timestamp */
+	int (*get_mac_tx_timestamp)(struct mac_device_info *hw, u64 *ts);
 };
 
 #define stmmac_core_init(__priv, __args...) \
@@ -413,6 +415,8 @@ struct stmmac_ops {
 	stmmac_do_callback(__priv, mac, rss_configure, __args)
 #define stmmac_update_vlan_hash(__priv, __args...) \
 	stmmac_do_void_callback(__priv, mac, update_vlan_hash, __args)
+#define stmmac_get_mac_tx_timestamp(__priv, __args...) \
+	stmmac_do_callback(__priv, mac, get_mac_tx_timestamp, __args)
 
 /* PTP and HW Timer helpers */
 struct stmmac_hwtimestamp {

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -432,6 +432,7 @@ static void stmmac_get_tx_hwtstamp(struct stmmac_priv *priv,
 				   struct dma_desc *p, struct sk_buff *skb)
 {
 	struct skb_shared_hwtstamps shhwtstamp;
+	bool found = false;
 	u64 ns = 0;
 
 	if (!priv->hwts_tx_en)
@@ -443,18 +444,20 @@ static void stmmac_get_tx_hwtstamp(struct stmmac_priv *priv,
 
 	/* check tx tstamp status */
 	if (stmmac_get_tx_timestamp_status(priv, p)) {
-		/* get the valid tstamp */
 		stmmac_get_timestamp(priv, p, priv->adv_ts, &ns);
+		found = true;
+	} else if (!stmmac_get_mac_tx_timestamp(priv, priv->hw, &ns)) {
+		found = true;
+	}
 
+	if (found) {
 		memset(&shhwtstamp, 0, sizeof(struct skb_shared_hwtstamps));
 		shhwtstamp.hwtstamp = ns_to_ktime(ns);
 
 		netdev_dbg(priv->dev, "get valid TX hw timestamp %llu\n", ns);
 		/* pass tstamp to stack */
 		skb_tstamp_tx(skb, &shhwtstamp);
 	}
-
-	return;
 }
 
 /* stmmac_get_rx_hwtstamp - get HW RX timestamps