net: phy: dp83tg720: add statistics support

Add support for reporting PHY statistics in the DP83TG720 driver. This
includes cumulative tracking of link loss events, transmit/receive
packet counts, and error counts. Implemented functions to update and
provide statistics via ethtool, with optional polling support enabled
through `PHY_POLL_STATS`.

Signed-off-by: Oleksij Rempel <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

Author: olerem

drivers/net/phy/dp83tg720.c

@@ -51,6 +51,9 @@
 /* Register 0x0405: Unknown Register */
 #define DP83TG720S_UNKNOWN_0405			0x405
 
+#define DP83TG720S_LINK_QUAL_3			0x547
+#define DP83TG720S_LINK_LOSS_CNT_MASK		GENMASK(15, 10)
+
 /* Register 0x0576: TDR Master Link Down Control */
 #define DP83TG720S_TDR_MASTER_LINK_DOWN		0x576
 
@@ -60,6 +63,29 @@
 /* In RGMII mode, Enable or disable the internal delay for TXD */
 #define DP83TG720S_RGMII_TX_CLK_SEL		BIT(0)
 
+/*
+ * DP83TG720S_PKT_STAT_x registers correspond to similarly named registers
+ * in the datasheet (PKT_STAT_1 through PKT_STAT_6). These registers store
+ * 32-bit or 16-bit counters for TX and RX statistics and must be read in
+ * sequence to ensure the counters are cleared correctly.
+ *
+ * - DP83TG720S_PKT_STAT_1: Contains TX packet count bits [15:0].
+ * - DP83TG720S_PKT_STAT_2: Contains TX packet count bits [31:16].
+ * - DP83TG720S_PKT_STAT_3: Contains TX error packet count.
+ * - DP83TG720S_PKT_STAT_4: Contains RX packet count bits [15:0].
+ * - DP83TG720S_PKT_STAT_5: Contains RX packet count bits [31:16].
+ * - DP83TG720S_PKT_STAT_6: Contains RX error packet count.
+ *
+ * Keeping the register names as defined in the datasheet helps maintain
+ * clarity and alignment with the documentation.
+ */
+#define DP83TG720S_PKT_STAT_1			0x639
+#define DP83TG720S_PKT_STAT_2			0x63a
+#define DP83TG720S_PKT_STAT_3			0x63b
+#define DP83TG720S_PKT_STAT_4			0x63c
+#define DP83TG720S_PKT_STAT_5			0x63d
+#define DP83TG720S_PKT_STAT_6			0x63e
+
 /* Register 0x083F: Unknown Register */
 #define DP83TG720S_UNKNOWN_083F			0x83f
 
@@ -69,6 +95,113 @@
 
 #define DP83TG720_SQI_MAX			7
 
+struct dp83tg720_stats {
+	u64 link_loss_cnt;
+	u64 tx_pkt_cnt;
+	u64 tx_err_pkt_cnt;
+	u64 rx_pkt_cnt;
+	u64 rx_err_pkt_cnt;
+};
+
+struct dp83tg720_priv {
+	struct dp83tg720_stats stats;
+};
+
+/**
+ * dp83tg720_update_stats - Update the PHY statistics for the DP83TD510 PHY.
+ * @phydev: Pointer to the phy_device structure.
+ *
+ * The function reads the PHY statistics registers and updates the statistics
+ * structure.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static int dp83tg720_update_stats(struct phy_device *phydev)
+{
+	struct dp83tg720_priv *priv = phydev->priv;
+	u32 count;
+	int ret;
+
+	/* Read the link loss count */
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TG720S_LINK_QUAL_3);
+	if (ret < 0)
+		return ret;
+	/* link_loss_cnt */
+	count = FIELD_GET(DP83TG720S_LINK_LOSS_CNT_MASK, ret);
+	priv->stats.link_loss_cnt += count;
+
+	/* The DP83TG720S_PKT_STAT registers are divided into two groups:
+	 * - Group 1 (TX stats): DP83TG720S_PKT_STAT_1 to DP83TG720S_PKT_STAT_3
+	 * - Group 2 (RX stats): DP83TG720S_PKT_STAT_4 to DP83TG720S_PKT_STAT_6
+	 *
+	 * Registers in each group are cleared only after reading them in a
+	 * plain sequence (e.g., 1, 2, 3 for Group 1 or 4, 5, 6 for Group 2).
+	 * Any deviation from the sequence, such as reading 1, 2, 1, 2, 3, will
+	 * prevent the group from being cleared. Additionally, the counters
+	 * for a group are frozen as soon as the first register in that group
+	 * is accessed.
+	 */
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TG720S_PKT_STAT_1);
+	if (ret < 0)
+		return ret;
+	/* tx_pkt_cnt_15_0 */
+	count = ret;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TG720S_PKT_STAT_2);
+	if (ret < 0)
+		return ret;
+	/* tx_pkt_cnt_31_16 */
+	count |= ret << 16;
+	priv->stats.tx_pkt_cnt += count;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TG720S_PKT_STAT_3);
+	if (ret < 0)
+		return ret;
+	/* tx_err_pkt_cnt */
+	priv->stats.tx_err_pkt_cnt += ret;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TG720S_PKT_STAT_4);
+	if (ret < 0)
+		return ret;
+	/* rx_pkt_cnt_15_0 */
+	count = ret;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TG720S_PKT_STAT_5);
+	if (ret < 0)
+		return ret;
+	/* rx_pkt_cnt_31_16 */
+	count |= ret << 16;
+	priv->stats.rx_pkt_cnt += count;
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_VEND2, DP83TG720S_PKT_STAT_6);
+	if (ret < 0)
+		return ret;
+	/* rx_err_pkt_cnt */
+	priv->stats.rx_err_pkt_cnt += ret;
+
+	return 0;
+}
+
+static void dp83tg720_get_link_stats(struct phy_device *phydev,
+				     struct ethtool_link_ext_stats *link_stats)
+{
+	struct dp83tg720_priv *priv = phydev->priv;
+
+	link_stats->link_down_events = priv->stats.link_loss_cnt;
+}
+
+static void dp83tg720_get_phy_stats(struct phy_device *phydev,
+				    struct ethtool_eth_phy_stats *eth_stats,
+				    struct ethtool_phy_stats *stats)
+{
+	struct dp83tg720_priv *priv = phydev->priv;
+
+	stats->tx_packets = priv->stats.tx_pkt_cnt;
+	stats->tx_errors = priv->stats.tx_err_pkt_cnt;
+	stats->rx_packets = priv->stats.rx_pkt_cnt;
+	stats->rx_errors = priv->stats.rx_err_pkt_cnt;
+}
+
 /**
  * dp83tg720_cable_test_start - Start the cable test for the DP83TG720 PHY.
  * @phydev: Pointer to the phy_device structure.
@@ -182,6 +315,11 @@ static int dp83tg720_cable_test_get_status(struct phy_device *phydev,
 
 	ethnl_cable_test_result(phydev, ETHTOOL_A_CABLE_PAIR_A, stat);
 
+	/* save the current stats before resetting the PHY */
+	ret = dp83tg720_update_stats(phydev);
+	if (ret)
+		return ret;
+
 	return phy_init_hw(phydev);
 }
 
@@ -217,6 +355,11 @@ static int dp83tg720_read_status(struct phy_device *phydev)
 	phy_sts = phy_read(phydev, DP83TG720S_MII_REG_10);
 	phydev->link = !!(phy_sts & DP83TG720S_LINK_STATUS);
 	if (!phydev->link) {
+		/* save the current stats before resetting the PHY */
+		ret = dp83tg720_update_stats(phydev);
+		if (ret)
+			return ret;
+
 		/* According to the "DP83TC81x, DP83TG72x Software
 		 * Implementation Guide", the PHY needs to be reset after a
 		 * link loss or if no link is created after at least 100ms.
@@ -341,12 +484,27 @@ static int dp83tg720_config_init(struct phy_device *phydev)
 	return genphy_c45_pma_baset1_read_master_slave(phydev);
 }
 
+static int dp83tg720_probe(struct phy_device *phydev)
+{
+	struct device *dev = &phydev->mdio.dev;
+	struct dp83tg720_priv *priv;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	phydev->priv = priv;
+
+	return 0;
+}
+
 static struct phy_driver dp83tg720_driver[] = {
 {
 	PHY_ID_MATCH_MODEL(DP83TG720S_PHY_ID),
 	.name		= "TI DP83TG720S",
 
 	.flags          = PHY_POLL_CABLE_TEST,
+	.probe		= dp83tg720_probe,
 	.config_aneg	= dp83tg720_config_aneg,
 	.read_status	= dp83tg720_read_status,
 	.get_features	= genphy_c45_pma_read_ext_abilities,
@@ -355,6 +513,9 @@ static struct phy_driver dp83tg720_driver[] = {
 	.get_sqi_max	= dp83tg720_get_sqi_max,
 	.cable_test_start = dp83tg720_cable_test_start,
 	.cable_test_get_status = dp83tg720_cable_test_get_status,
+	.get_link_stats	= dp83tg720_get_link_stats,
+	.get_phy_stats	= dp83tg720_get_phy_stats,
+	.update_stats	= dp83tg720_update_stats,
 
 	.suspend	= genphy_suspend,
 	.resume		= genphy_resume,