[PATCH v1 2/2] net: stmmac: eic7700: enable clocks before syscon access and correct RX sampling timing

[lizhi2@eswincomputing.com]

From: Zhi Li <lizhi2@eswincomputing.com>

The second Ethernet controller (eth1) on the Eswin EIC7700 SoC may fail
to sample RX data correctly at Gigabit speed due to EIC7700-specific
receive clock to data skew at the MAC input.

The existing internal delay configuration does not provide sufficient
adjustment range to compensate for this condition. Update the EIC7700
DWMAC glue driver to optionally apply EIC7700-specific clock sampling
inversion for Gigabit operation.

TXD and RXD delay registers are explicitly cleared during initialization
to override any residual configuration left by the bootloader. All HSP
CSR register accesses are performed only after the required clocks are
enabled.

Fixes: ea77dbbdbc4e ("net: stmmac: add Eswin EIC7700 glue driver")
Signed-off-by: Zhi Li <lizhi2@eswincomputing.com>
---
 .../ethernet/stmicro/stmmac/dwmac-eic7700.c   | 132 +++++++++++++-----
 1 file changed, 97 insertions(+), 35 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-eic7700.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-eic7700.c
index bcb8e000e720..68c476612af9 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-eic7700.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-eic7700.c
@@ -28,20 +28,34 @@
 
 /*
  * TX/RX Clock Delay Bit Masks:
- * - TX Delay: bits [14:8] — TX_CLK delay (unit: 0.1ns per bit)
- * - RX Delay: bits [30:24] — RX_CLK delay (unit: 0.1ns per bit)
+ * - TX Delay: bits [14:8] — TX_CLK delay (unit: 0.02ns per bit)
+ * - TX Invert : bit  [15]
+ * - RX Delay: bits [30:24] — RX_CLK delay (unit: 0.02ns per bit)
+ * - RX Invert : bit  [31]
  */
 #define EIC7700_ETH_TX_ADJ_DELAY	GENMASK(14, 8)
 #define EIC7700_ETH_RX_ADJ_DELAY	GENMASK(30, 24)
+#define EIC7700_ETH_TX_INV_DELAY	BIT(15)
+#define EIC7700_ETH_RX_INV_DELAY	BIT(31)
 
-#define EIC7700_MAX_DELAY_UNIT 0x7F
+#define EIC7700_MAX_DELAY_STEPS 0x7F
 
 static const char * const eic7700_clk_names[] = {
 	"tx", "axi", "cfg",
 };
 
 struct eic7700_qos_priv {
+	struct device *dev;
 	struct plat_stmmacenet_data *plat_dat;
+	struct regmap *eic7700_hsp_regmap;
+	u32 eth_axi_lp_ctrl_offset;
+	u32 eth_phy_ctrl_offset;
+	u32 eth_txd_offset;
+	u32 eth_clk_offset;
+	u32 eth_rxd_offset;
+	u32 eth_clk_dly_param;
+	bool eth_tx_clk_inv;
+	bool eth_rx_clk_inv;
 };
 
 static int eic7700_clks_config(void *priv, bool enabled)
@@ -61,8 +75,27 @@ static int eic7700_clks_config(void *priv, bool enabled)
 static int eic7700_dwmac_init(struct device *dev, void *priv)
 {
 	struct eic7700_qos_priv *dwc = priv;
+	u32 eth_phy_ctrl_regset;
+	int ret = 0;
 
-	return eic7700_clks_config(dwc, true);
+	ret = eic7700_clks_config(dwc, true);
+	if (ret)
+		return ret;
+
+	regmap_read(dwc->eic7700_hsp_regmap, dwc->eth_phy_ctrl_offset,
+		    &eth_phy_ctrl_regset);
+	eth_phy_ctrl_regset |=
+		(EIC7700_ETH_TX_CLK_SEL | EIC7700_ETH_PHY_INTF_SELI);
+	regmap_write(dwc->eic7700_hsp_regmap, dwc->eth_phy_ctrl_offset,
+		     eth_phy_ctrl_regset);
+
+	regmap_write(dwc->eic7700_hsp_regmap, dwc->eth_axi_lp_ctrl_offset,
+		     EIC7700_ETH_CSYSREQ_VAL);
+
+	regmap_write(dwc->eic7700_hsp_regmap, dwc->eth_txd_offset, 0);
+	regmap_write(dwc->eic7700_hsp_regmap, dwc->eth_rxd_offset, 0);
+
+	return ret;
 }
 
 static void eic7700_dwmac_exit(struct device *dev, void *priv)
@@ -88,17 +121,34 @@ static int eic7700_dwmac_resume(struct device *dev, void *priv)
 	return ret;
 }
 
+static void eic7700_dwmac_fix_speed(void *priv, int speed, unsigned int mode)
+{
+	struct eic7700_qos_priv *dwc = (struct eic7700_qos_priv *)priv;
+	u32 dly_param = dwc->eth_clk_dly_param;
+
+	switch (speed) {
+	case SPEED_1000:
+		if (dwc->eth_tx_clk_inv)
+			dly_param |= EIC7700_ETH_TX_INV_DELAY;
+		if (dwc->eth_rx_clk_inv)
+			dly_param |= EIC7700_ETH_RX_INV_DELAY;
+		break;
+	case SPEED_100:
+	case SPEED_10:
+		break;
+	default:
+		dev_err(dwc->dev, "invalid speed %u\n", speed);
+		break;
+	}
+
+	regmap_write(dwc->eic7700_hsp_regmap, dwc->eth_clk_offset, dly_param);
+}
+
 static int eic7700_dwmac_probe(struct platform_device *pdev)
 {
 	struct plat_stmmacenet_data *plat_dat;
 	struct stmmac_resources stmmac_res;
 	struct eic7700_qos_priv *dwc_priv;
-	struct regmap *eic7700_hsp_regmap;
-	u32 eth_axi_lp_ctrl_offset;
-	u32 eth_phy_ctrl_offset;
-	u32 eth_phy_ctrl_regset;
-	u32 eth_rxd_dly_offset;
-	u32 eth_dly_param = 0;
 	u32 delay_ps;
 	int i, ret;
 
@@ -116,13 +166,16 @@ static int eic7700_dwmac_probe(struct platform_device *pdev)
 	if (!dwc_priv)
 		return -ENOMEM;
 
+	dwc_priv->dev = &pdev->dev;
+
 	/* Read rx-internal-delay-ps and update rx_clk delay */
 	if (!of_property_read_u32(pdev->dev.of_node,
 				  "rx-internal-delay-ps", &delay_ps)) {
-		u32 val = min(delay_ps / 100, EIC7700_MAX_DELAY_UNIT);
+		u32 val = min(delay_ps / 20, EIC7700_MAX_DELAY_STEPS);
 
-		eth_dly_param &= ~EIC7700_ETH_RX_ADJ_DELAY;
-		eth_dly_param |= FIELD_PREP(EIC7700_ETH_RX_ADJ_DELAY, val);
+		dwc_priv->eth_clk_dly_param &= ~EIC7700_ETH_RX_ADJ_DELAY;
+		dwc_priv->eth_clk_dly_param |=
+				 FIELD_PREP(EIC7700_ETH_RX_ADJ_DELAY, val);
 	} else {
 		return dev_err_probe(&pdev->dev, -EINVAL,
 			"missing required property rx-internal-delay-ps\n");
@@ -131,55 +184,63 @@ static int eic7700_dwmac_probe(struct platform_device *pdev)
 	/* Read tx-internal-delay-ps and update tx_clk delay */
 	if (!of_property_read_u32(pdev->dev.of_node,
 				  "tx-internal-delay-ps", &delay_ps)) {
-		u32 val = min(delay_ps / 100, EIC7700_MAX_DELAY_UNIT);
+		u32 val = min(delay_ps / 20, EIC7700_MAX_DELAY_STEPS);
 
-		eth_dly_param &= ~EIC7700_ETH_TX_ADJ_DELAY;
-		eth_dly_param |= FIELD_PREP(EIC7700_ETH_TX_ADJ_DELAY, val);
+		dwc_priv->eth_clk_dly_param &= ~EIC7700_ETH_TX_ADJ_DELAY;
+		dwc_priv->eth_clk_dly_param |=
+				 FIELD_PREP(EIC7700_ETH_TX_ADJ_DELAY, val);
 	} else {
 		return dev_err_probe(&pdev->dev, -EINVAL,
 			"missing required property tx-internal-delay-ps\n");
 	}
 
-	eic7700_hsp_regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
-							     "eswin,hsp-sp-csr");
-	if (IS_ERR(eic7700_hsp_regmap))
+	dwc_priv->eth_tx_clk_inv =
+	    of_property_read_bool(pdev->dev.of_node, "eswin,tx-clk-invert");
+	dwc_priv->eth_rx_clk_inv =
+	    of_property_read_bool(pdev->dev.of_node, "eswin,rx-clk-invert");
+
+	dwc_priv->eic7700_hsp_regmap =
+			syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+							"eswin,hsp-sp-csr");
+	if (IS_ERR(dwc_priv->eic7700_hsp_regmap))
 		return dev_err_probe(&pdev->dev,
-				PTR_ERR(eic7700_hsp_regmap),
+				PTR_ERR(dwc_priv->eic7700_hsp_regmap),
 				"Failed to get hsp-sp-csr regmap\n");
 
 	ret = of_property_read_u32_index(pdev->dev.of_node,
 					 "eswin,hsp-sp-csr",
-					 1, &eth_phy_ctrl_offset);
+					 1, &dwc_priv->eth_phy_ctrl_offset);
 	if (ret)
 		return dev_err_probe(&pdev->dev, ret,
 				     "can't get eth_phy_ctrl_offset\n");
 
-	regmap_read(eic7700_hsp_regmap, eth_phy_ctrl_offset,
-		    &eth_phy_ctrl_regset);
-	eth_phy_ctrl_regset |=
-		(EIC7700_ETH_TX_CLK_SEL | EIC7700_ETH_PHY_INTF_SELI);
-	regmap_write(eic7700_hsp_regmap, eth_phy_ctrl_offset,
-		     eth_phy_ctrl_regset);
-
 	ret = of_property_read_u32_index(pdev->dev.of_node,
 					 "eswin,hsp-sp-csr",
-					 2, &eth_axi_lp_ctrl_offset);
+					 2, &dwc_priv->eth_axi_lp_ctrl_offset);
 	if (ret)
 		return dev_err_probe(&pdev->dev, ret,
 				     "can't get eth_axi_lp_ctrl_offset\n");
 
-	regmap_write(eic7700_hsp_regmap, eth_axi_lp_ctrl_offset,
-		     EIC7700_ETH_CSYSREQ_VAL);
+	ret = of_property_read_u32_index(pdev->dev.of_node,
+					 "eswin,hsp-sp-csr",
+					 3, &dwc_priv->eth_txd_offset);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret,
+				     "can't get eth_txd_offset\n");
 
 	ret = of_property_read_u32_index(pdev->dev.of_node,
 					 "eswin,hsp-sp-csr",
-					 3, &eth_rxd_dly_offset);
+					 4, &dwc_priv->eth_clk_offset);
 	if (ret)
 		return dev_err_probe(&pdev->dev, ret,
-				     "can't get eth_rxd_dly_offset\n");
+				     "can't get eth_clk_offset\n");
 
-	regmap_write(eic7700_hsp_regmap, eth_rxd_dly_offset,
-		     eth_dly_param);
+	ret = of_property_read_u32_index(pdev->dev.of_node,
+					 "eswin,hsp-sp-csr",
+					 5, &dwc_priv->eth_rxd_offset);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret,
+				     "can't get eth_rxd_offset\n");
 
 	plat_dat->num_clks = ARRAY_SIZE(eic7700_clk_names);
 	plat_dat->clks = devm_kcalloc(&pdev->dev,
@@ -208,6 +269,7 @@ static int eic7700_dwmac_probe(struct platform_device *pdev)
 	plat_dat->exit = eic7700_dwmac_exit;
 	plat_dat->suspend = eic7700_dwmac_suspend;
 	plat_dat->resume = eic7700_dwmac_resume;
+	plat_dat->fix_mac_speed = eic7700_dwmac_fix_speed;
 
 	return devm_stmmac_pltfr_probe(pdev, plat_dat, &stmmac_res);
 }
-- 
2.25.1