[PATCH] net: ethernet: mtk_eth_soc: implement Clause 45 MDIO access

[Daniel Golle]

Implement read and write access to IEEE 802.3 Clause 45 Ethernet
phy registers.
Tested on the Ubiquiti UniFi 6 LR access point featuring
MediaTek MT7622BV WiSoC with Aquantia AQR112C.

Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 56 ++++++++++++++++++---
 drivers/net/ethernet/mediatek/mtk_eth_soc.h |  3 ++
 2 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index bcb91b01e69f5..9f896a90a4c4c 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -102,10 +102,30 @@ static u32 _mtk_mdio_write(struct mtk_eth *eth, u32 phy_addr,
 
 	write_data &= 0xffff;
 
-	mtk_w32(eth, PHY_IAC_ACCESS | PHY_IAC_START | PHY_IAC_WRITE |
-		(phy_register << PHY_IAC_REG_SHIFT) |
-		(phy_addr << PHY_IAC_ADDR_SHIFT) | write_data,
-		MTK_PHY_IAC);
+	if (phy_register & MII_ADDR_C45) {
+		u8 dev_num = (phy_register >> 16) & 0x1f;
+		u16 reg = (u16)(phy_register & 0xffff);
+
+		mtk_w32(eth, PHY_IAC_ACCESS | PHY_IAC_START_C45 | PHY_IAC_SET_ADDR |
+			(phy_addr << PHY_IAC_ADDR_SHIFT) |
+			(dev_num << PHY_IAC_REG_SHIFT) |
+			reg,
+			MTK_PHY_IAC);
+
+		if (mtk_mdio_busy_wait(eth))
+			return 0xffff;
+
+		mtk_w32(eth, PHY_IAC_ACCESS | PHY_IAC_START_C45 | PHY_IAC_WRITE |
+			(phy_addr << PHY_IAC_ADDR_SHIFT) |
+			(dev_num << PHY_IAC_REG_SHIFT) |
+			write_data,
+			MTK_PHY_IAC);
+	} else {
+		mtk_w32(eth, PHY_IAC_ACCESS | PHY_IAC_START | PHY_IAC_WRITE |
+			(phy_register << PHY_IAC_REG_SHIFT) |
+			(phy_addr << PHY_IAC_ADDR_SHIFT) | write_data,
+			MTK_PHY_IAC);
+	}
 
 	if (mtk_mdio_busy_wait(eth))
 		return -1;
@@ -120,10 +140,29 @@ static u32 _mtk_mdio_read(struct mtk_eth *eth, int phy_addr, int phy_reg)
 	if (mtk_mdio_busy_wait(eth))
 		return 0xffff;
 
-	mtk_w32(eth, PHY_IAC_ACCESS | PHY_IAC_START | PHY_IAC_READ |
-		(phy_reg << PHY_IAC_REG_SHIFT) |
-		(phy_addr << PHY_IAC_ADDR_SHIFT),
-		MTK_PHY_IAC);
+	if (phy_reg & MII_ADDR_C45) {
+		u8 dev_num = (phy_reg >> 16) & 0x1f;
+		u16 reg = (u16)(phy_reg & 0xffff);
+
+		mtk_w32(eth, PHY_IAC_ACCESS | PHY_IAC_START_C45 | PHY_IAC_SET_ADDR |
+			(phy_addr << PHY_IAC_ADDR_SHIFT) |
+			(dev_num << PHY_IAC_REG_SHIFT) |
+			reg,
+			MTK_PHY_IAC);
+
+		if (mtk_mdio_busy_wait(eth))
+			return 0xffff;
+
+		mtk_w32(eth, PHY_IAC_ACCESS | PHY_IAC_START_C45 | PHY_IAC_READ_C45 |
+			(phy_addr << PHY_IAC_ADDR_SHIFT) |
+			(dev_num << PHY_IAC_REG_SHIFT),
+			MTK_PHY_IAC);
+	} else {
+		mtk_w32(eth, PHY_IAC_ACCESS | PHY_IAC_START | PHY_IAC_READ |
+			(phy_reg << PHY_IAC_REG_SHIFT) |
+			(phy_addr << PHY_IAC_ADDR_SHIFT),
+			MTK_PHY_IAC);
+	}
 
 	if (mtk_mdio_busy_wait(eth))
 		return 0xffff;
@@ -497,6 +536,7 @@ static int mtk_mdio_init(struct mtk_eth *eth)
 	eth->mii_bus->name = "mdio";
 	eth->mii_bus->read = mtk_mdio_read;
 	eth->mii_bus->write = mtk_mdio_write;
+	eth->mii_bus->probe_capabilities = MDIOBUS_C22_C45;
 	eth->mii_bus->priv = eth;
 	eth->mii_bus->parent = eth->dev;
 
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index 5ef70dd8b49c6..b73d8adc9d24c 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -341,9 +341,12 @@
 /* PHY Indirect Access Control registers */
 #define MTK_PHY_IAC		0x10004
 #define PHY_IAC_ACCESS		BIT(31)
+#define PHY_IAC_SET_ADDR	0
 #define PHY_IAC_READ		BIT(19)
+#define PHY_IAC_READ_C45	(BIT(18) | BIT(19))
 #define PHY_IAC_WRITE		BIT(18)
 #define PHY_IAC_START		BIT(16)
+#define PHY_IAC_START_C45	0
 #define PHY_IAC_ADDR_SHIFT	20
 #define PHY_IAC_REG_SHIFT	25
 #define PHY_IAC_TIMEOUT		HZ
-- 
2.34.1