net-next: stmmac: mediatek: add more support for RMII

MT2712 SoC can provide the rmii reference clock, and the clock
will output from TXC pin only, which means ref_clk pin of external
PHY should connect to TXC pin in this case.
Add corresponding clock and timing settings.
Signed-off-by: Biao Huang <biao.huang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c

@@ -55,6 +55,8 @@ struct mediatek_dwmac_plat_data {
 	struct regmap *peri_regmap;
 	struct device *dev;
 	phy_interface_t phy_mode;
+	int num_clks_to_config;
+	bool rmii_clk_from_mac;
 	bool rmii_rxc;
 };
 
@@ -73,21 +75,33 @@ struct mediatek_dwmac_variant {
 
 /* list of clocks required for mac */
 static const char * const mt2712_dwmac_clk_l[] = {
-	"axi", "apb", "mac_main", "ptp_ref"
+	"axi", "apb", "mac_main", "ptp_ref", "rmii_internal"
 };
 
 static int mt2712_set_interface(struct mediatek_dwmac_plat_data *plat)
 {
+	int rmii_clk_from_mac = plat->rmii_clk_from_mac ? RMII_CLK_SRC_INTERNAL : 0;
 	int rmii_rxc = plat->rmii_rxc ? RMII_CLK_SRC_RXC : 0;
 	u32 intf_val = 0;
 
+	/* The clock labeled as "rmii_internal" in mt2712_dwmac_clk_l is needed
+	 * only in RMII(when MAC provides the reference clock), and useless for
+	 * RGMII/MII/RMII(when PHY provides the reference clock).
+	 * num_clks_to_config indicates the real number of clocks should be
+	 * configured, equals to (plat->variant->num_clks - 1) in default for all the case,
+	 * then +1 for rmii_clk_from_mac case.
+	 */
+	plat->num_clks_to_config = plat->variant->num_clks - 1;
+
 	/* select phy interface in top control domain */
 	switch (plat->phy_mode) {
 	case PHY_INTERFACE_MODE_MII:
 		intf_val |= PHY_INTF_MII;
 		break;
 	case PHY_INTERFACE_MODE_RMII:
-		intf_val |= (PHY_INTF_RMII | rmii_rxc);
+		if (plat->rmii_clk_from_mac)
+			plat->num_clks_to_config++;
+		intf_val |= (PHY_INTF_RMII | rmii_rxc | rmii_clk_from_mac);
 		break;
 	case PHY_INTERFACE_MODE_RGMII:
 	case PHY_INTERFACE_MODE_RGMII_TXID:
@@ -173,7 +187,21 @@ static int mt2712_set_delay(struct mediatek_dwmac_plat_data *plat)
 		delay_val |= FIELD_PREP(ETH_DLY_RXC_INV, mac_delay->rx_inv);
 		break;
 	case PHY_INTERFACE_MODE_RMII:
-		/* the rmii reference clock is from external phy,
+		if (plat->rmii_clk_from_mac) {
+			/* case 1: mac provides the rmii reference clock,
+			 * and the clock output to TXC pin.
+			 * The egress timing can be adjusted by GTXC delay macro circuit.
+			 * The ingress timing can be adjusted by TXC delay macro circuit.
+			 */
+			delay_val |= FIELD_PREP(ETH_DLY_TXC_ENABLE, !!mac_delay->rx_delay);
+			delay_val |= FIELD_PREP(ETH_DLY_TXC_STAGES, mac_delay->rx_delay);
+			delay_val |= FIELD_PREP(ETH_DLY_TXC_INV, mac_delay->rx_inv);
+
+			delay_val |= FIELD_PREP(ETH_DLY_GTXC_ENABLE, !!mac_delay->tx_delay);
+			delay_val |= FIELD_PREP(ETH_DLY_GTXC_STAGES, mac_delay->tx_delay);
+			delay_val |= FIELD_PREP(ETH_DLY_GTXC_INV, mac_delay->tx_inv);
+		} else {
+			/* case 2: the rmii reference clock is from external phy,
 			 * and the property "rmii_rxc" indicates which pin(TXC/RXC)
 			 * the reference clk is connected to. The reference clock is a
 			 * received signal, so rx_delay/rx_inv are used to indicate
@@ -202,6 +230,7 @@ static int mt2712_set_delay(struct mediatek_dwmac_plat_data *plat)
 			 */
 			if (mac_delay->tx_inv)
 				fine_val = ETH_RMII_DLY_TX_INV;
+		}
 		break;
 	case PHY_INTERFACE_MODE_RGMII:
 	case PHY_INTERFACE_MODE_RGMII_TXID:
@@ -278,6 +307,7 @@ static int mediatek_dwmac_config_dt(struct mediatek_dwmac_plat_data *plat)
 	mac_delay->tx_inv = of_property_read_bool(plat->np, "mediatek,txc-inverse");
 	mac_delay->rx_inv = of_property_read_bool(plat->np, "mediatek,rxc-inverse");
 	plat->rmii_rxc = of_property_read_bool(plat->np, "mediatek,rmii-rxc");
+	plat->rmii_clk_from_mac = of_property_read_bool(plat->np, "mediatek,rmii-clk-from-mac");
 
 	return 0;
 }
@@ -294,6 +324,8 @@ static int mediatek_dwmac_clk_init(struct mediatek_dwmac_plat_data *plat)
 	for (i = 0; i < num; i++)
 		plat->clks[i].id = variant->clk_list[i];
 
+	plat->num_clks_to_config = variant->num_clks;
+
 	return devm_clk_bulk_get(plat->dev, num, plat->clks);
 }
 
@@ -321,7 +353,7 @@ static int mediatek_dwmac_init(struct platform_device *pdev, void *priv)
 		return ret;
 	}
 
-	ret = clk_bulk_prepare_enable(variant->num_clks, plat->clks);
+	ret = clk_bulk_prepare_enable(plat->num_clks_to_config, plat->clks);
 	if (ret) {
 		dev_err(plat->dev, "failed to enable clks, err = %d\n", ret);
 		return ret;
@@ -336,9 +368,8 @@ static int mediatek_dwmac_init(struct platform_device *pdev, void *priv)
 static void mediatek_dwmac_exit(struct platform_device *pdev, void *priv)
 {
 	struct mediatek_dwmac_plat_data *plat = priv;
-	const struct mediatek_dwmac_variant *variant = plat->variant;
 
-	clk_bulk_disable_unprepare(variant->num_clks, plat->clks);
+	clk_bulk_disable_unprepare(plat->num_clks_to_config, plat->clks);
 
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);