net: phy: realtek: enable serdes option mode for RTL8226-CG

The RTL8226-CG can make use of the serdes option mode feature to
dynamically switch between SGMII and 2500base-X. From what is
known the setup sequence is much simpler with no magic values.

Convert the exiting config_init() into a helper that configures
the PHY depending on generation 1 or 2. Call the helper from two
separated new config_init() functions.

Finally convert the phy_driver specs of the RTL8226-CG to make
use of the new configuration and switch over to the extended
read_status() function to dynamically change the interface
according to the serdes mode.

Remark! The logic could be simpler if the serdes mode could be
set before all other generation 2 magic values. Due to missing
RTL8221B test hardware the mmd command order was kept.

Tested on Zyxel XGS1210-12.

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://patch.msgid.link/20250815082009.3678865-1-markus.stockhausen@gmx.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/realtek/realtek_main.c b/drivers/net/phy/realtek/realtek_main.c
index 904fa8b1aa0381e955889b7527ed64301c6ce005..b2d0c0f88f751947b32919b02bb8a9a312e5ebec 100644 (file)
--- a/drivers/net/phy/realtek/realtek_main.c
+++ b/drivers/net/phy/realtek/realtek_main.c
@@ -1146,7 +1146,7 @@ static int rtl822x_probe(struct phy_device *phydev)
        return 0;
 }
 
-static int rtl822xb_config_init(struct phy_device *phydev)
+static int rtl822x_set_serdes_option_mode(struct phy_device *phydev, bool gen1)
 {
        bool has_2500, has_sgmii;
        u16 mode;
@@ -1181,15 +1181,18 @@ static int rtl822xb_config_init(struct phy_device *phydev)
        /* the following sequence with magic numbers sets up the SerDes
         * option mode
         */
-       ret = phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x75f3, 0);
-       if (ret < 0)
-               return ret;
+
+       if (!gen1) {
+               ret = phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x75f3, 0);
+               if (ret < 0)
+                       return ret;
+       }
 
        ret = phy_modify_mmd_changed(phydev, MDIO_MMD_VEND1,
                                     RTL822X_VND1_SERDES_OPTION,
                                     RTL822X_VND1_SERDES_OPTION_MODE_MASK,
                                     mode);
-       if (ret < 0)
+       if (gen1 || ret < 0)
                return ret;
 
        ret = phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x6a04, 0x0503);
@@ -1203,6 +1206,16 @@ static int rtl822xb_config_init(struct phy_device *phydev)
        return phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x6f11, 0x8020);
 }
 
+static int rtl822x_config_init(struct phy_device *phydev)
+{
+       return rtl822x_set_serdes_option_mode(phydev, true);
+}
+
+static int rtl822xb_config_init(struct phy_device *phydev)
+{
+       return rtl822x_set_serdes_option_mode(phydev, false);
+}
+
 static int rtl822xb_get_rate_matching(struct phy_device *phydev,
                                      phy_interface_t iface)
 {
@@ -1801,7 +1814,8 @@ static struct phy_driver realtek_drvs[] = {
                .soft_reset     = rtl822x_c45_soft_reset,
                .get_features   = rtl822x_c45_get_features,
                .config_aneg    = rtl822x_c45_config_aneg,
-               .read_status    = rtl822x_c45_read_status,
+               .config_init    = rtl822x_config_init,
+               .read_status    = rtl822xb_c45_read_status,
                .suspend        = genphy_c45_pma_suspend,
                .resume         = rtlgen_c45_resume,
        }, {