net: phy: realtek: Fix MMD access on RTL8126A-integrated PHY

All MMD reads return 0 for the RTL8126A-integrated PHY. Therefore phylib
assumes it doesn't support EEE, what results in higher power consumption,
and a significantly higher chip temperature in my case.
To fix this split out the PHY driver for the RTL8126A-integrated PHY
and set the read_mmd/write_mmd callbacks to read from vendor-specific
registers.

Fixes: 5befa372 ("net: phy: realtek: add support for RTL8126A-integrated 5Gbps PHY")
Cc: stable@vger.kernel.org
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/realtek.c

@@ -1081,6 +1081,16 @@ static int rtl8221b_vn_cg_c45_match_phy_device(struct phy_device *phydev)
 	return rtlgen_is_c45_match(phydev, RTL_8221B_VN_CG, true);
 }
 
+static int rtl8251b_c22_match_phy_device(struct phy_device *phydev)
+{
+	return rtlgen_is_c45_match(phydev, RTL_8251B, false);
+}
+
+static int rtl8251b_c45_match_phy_device(struct phy_device *phydev)
+{
+	return rtlgen_is_c45_match(phydev, RTL_8251B, true);
+}
+
 static int rtlgen_resume(struct phy_device *phydev)
 {
 	int ret = genphy_resume(phydev);
@@ -1418,7 +1428,7 @@ static struct phy_driver realtek_drvs[] = {
 		.suspend        = genphy_c45_pma_suspend,
 		.resume         = rtlgen_c45_resume,
 	}, {
-		PHY_ID_MATCH_EXACT(0x001cc862),
+		.match_phy_device = rtl8251b_c45_match_phy_device,
 		.name           = "RTL8251B 5Gbps PHY",
 		.get_features   = rtl822x_get_features,
 		.config_aneg    = rtl822x_config_aneg,
@@ -1427,6 +1437,18 @@ static struct phy_driver realtek_drvs[] = {
 		.resume         = rtlgen_resume,
 		.read_page      = rtl821x_read_page,
 		.write_page     = rtl821x_write_page,
+	}, {
+		.match_phy_device = rtl8251b_c22_match_phy_device,
+		.name           = "RTL8126A-internal 5Gbps PHY",
+		.get_features   = rtl822x_get_features,
+		.config_aneg    = rtl822x_config_aneg,
+		.read_status    = rtl822x_read_status,
+		.suspend        = genphy_suspend,
+		.resume         = rtlgen_resume,
+		.read_page      = rtl821x_read_page,
+		.write_page     = rtl821x_write_page,
+		.read_mmd	= rtl822x_read_mmd,
+		.write_mmd	= rtl822x_write_mmd,
 	}, {
 		PHY_ID_MATCH_EXACT(0x001ccad0),
 		.name		= "RTL8224 2.5Gbps PHY",