net: ethernet: mtk-star-emac: add timing adjustment support

Add simple clock inversion for timing adjustment in driver.
Add property "mediatek,txc-inverse" or "mediatek,rxc-inverse" to
device node when necessary.
Signed-off-by: Biao Huang <biao.huang@mediatek.com>
Signed-off-by: Yinghua Pan <ot_yinghua.pan@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_star_emac.c

@@ -130,6 +130,11 @@ static const char *const mtk_star_clk_names[] = { "core", "reg", "trans" };
 #define MTK_STAR_REG_INT_MASK			0x0054
 #define MTK_STAR_BIT_INT_MASK_FNRC		BIT(6)
 
+/* Delay-Macro Register */
+#define MTK_STAR_REG_TEST0			0x0058
+#define MTK_STAR_BIT_INV_RX_CLK			BIT(30)
+#define MTK_STAR_BIT_INV_TX_CLK			BIT(31)
+
 /* Misc. Config Register */
 #define MTK_STAR_REG_TEST1			0x005c
 #define MTK_STAR_BIT_TEST1_RST_HASH_MBIST	BIT(31)
@@ -267,6 +272,8 @@ struct mtk_star_priv {
 	int duplex;
 	int pause;
 	bool rmii_rxc;
+	bool rx_inv;
+	bool tx_inv;
 
 	const struct mtk_star_compat *compat_data;
 
@@ -1449,6 +1456,24 @@ static void mtk_star_clk_disable_unprepare(void *data)
 	clk_bulk_disable_unprepare(MTK_STAR_NCLKS, priv->clks);
 }
 
+static int mtk_star_set_timing(struct mtk_star_priv *priv)
+{
+	struct device *dev = mtk_star_get_dev(priv);
+	unsigned int delay_val = 0;
+
+	switch (priv->phy_intf) {
+	case PHY_INTERFACE_MODE_RMII:
+		delay_val |= FIELD_PREP(MTK_STAR_BIT_INV_RX_CLK, priv->rx_inv);
+		delay_val |= FIELD_PREP(MTK_STAR_BIT_INV_TX_CLK, priv->tx_inv);
+		break;
+	default:
+		dev_err(dev, "This interface not supported\n");
+		return -EINVAL;
+	}
+
+	return regmap_write(priv->regs, MTK_STAR_REG_TEST0, delay_val);
+}
+
 static int mtk_star_probe(struct platform_device *pdev)
 {
 	struct device_node *of_node;
@@ -1531,6 +1556,8 @@ static int mtk_star_probe(struct platform_device *pdev)
 	}
 
 	priv->rmii_rxc = of_property_read_bool(of_node, "mediatek,rmii-rxc");
+	priv->rx_inv = of_property_read_bool(of_node, "mediatek,rxc-inverse");
+	priv->tx_inv = of_property_read_bool(of_node, "mediatek,txc-inverse");
 
 	if (priv->compat_data->set_interface_mode) {
 		ret = priv->compat_data->set_interface_mode(ndev);
@@ -1540,6 +1567,12 @@ static int mtk_star_probe(struct platform_device *pdev)
 		}
 	}
 
+	ret = mtk_star_set_timing(priv);
+	if (ret) {
+		dev_err(dev, "Failed to set timing, err = %d\n", ret);
+		return -EINVAL;
+	}
+
 	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
 	if (ret) {
 		dev_err(dev, "unsupported DMA mask\n");