Add support for MDI-X status and configuration

Signed-off-by: Oleksij Rempel <o.rem...@pengutronix.de>
---
 drivers/net/phy/micrel.c | 101 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 12106fbea565..ec409b2cb984 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -28,6 +28,19 @@
 #include <linux/clk.h>
 #include <linux/delay.h>
 
+/* Device specific MII_BMCR (Reg 0) bits */
+/* 1 = HP Auto MDI/MDI-X mode, 0 = Microchip Auto MDI/MDI-X mode */
+#define KSZ886X_BMCR_HP_MDIX                   BIT(5)
+/* 1 = Force MDI (transmit on RXP/RXM pins), 0 = Normal operation
+ * (transmit on TXP/TXM pins)
+ */
+#define KSZ886X_BMCR_FORCE_MDI                 BIT(4)
+/* 1 = Disable auto MDI-X */
+#define KSZ886X_BMCR_DISABLE_AUTO_MDIX         BIT(3)
+#define KSZ886X_BMCR_DISABLE_FAR_END_FAULT     BIT(2)
+#define KSZ886X_BMCR_DISABLE_TRANSMIT          BIT(1)
+#define KSZ886X_BMCR_DISABLE_LED               BIT(0)
+
 /* Operation Mode Strap Override */
 #define MII_KSZPHY_OMSO                                0x16
 #define KSZPHY_OMSO_FACTORY_TEST               BIT(15)
@@ -58,6 +71,7 @@
 /* bitmap of PHY register to set interrupt mode */
 #define KSZPHY_CTRL_INT_ACTIVE_HIGH            BIT(9)
 #define KSZPHY_RMII_REF_CLK_SEL                        BIT(7)
+#define KSZ886X_CTRL_MDIX_STAT                 BIT(4)
 
 /* Write/read to/from extended registers */
 #define MII_KSZPHY_EXTREG                       0x0b
@@ -1010,6 +1024,91 @@ static int ksz8873mll_config_aneg(struct phy_device 
*phydev)
        return 0;
 }
 
+static int ksz886x_config_mdix(struct phy_device *phydev, u8 ctrl)
+{
+       u16 val;
+
+       switch (ctrl) {
+       case ETH_TP_MDI:
+               val = KSZ886X_BMCR_DISABLE_AUTO_MDIX;
+               break;
+       case ETH_TP_MDI_X:
+               /* Note: The naming of the bit KSZ886X_BMCR_FORCE_MDI is bit
+                * counter intuitive, the "-X" in "1 = Force MDI" in the data
+                * sheet seems to be missing:
+                * 1 = Force MDI (sic!) (transmit on RX+/RX- pins)
+                * 0 = Normal operation (transmit on TX+/TX- pins)
+                */
+               val = KSZ886X_BMCR_DISABLE_AUTO_MDIX | KSZ886X_BMCR_FORCE_MDI;
+               break;
+       case ETH_TP_MDI_AUTO:
+               val = 0;
+               break;
+       default:
+               return 0;
+       }
+
+       return phy_modify(phydev, MII_BMCR,
+                         KSZ886X_BMCR_HP_MDIX | KSZ886X_BMCR_FORCE_MDI |
+                         KSZ886X_BMCR_DISABLE_AUTO_MDIX,
+                         KSZ886X_BMCR_HP_MDIX | val);
+}
+
+static int ksz886x_config_aneg(struct phy_device *phydev)
+{
+       int ret;
+
+       ret = genphy_config_aneg(phydev);
+       if (ret)
+               return ret;
+
+       /* The MDI-X configuration is automatically changed by the PHY after
+        * switching from autoneg off to on. So, take MDI-X configuration under
+        * own control and set it after autoneg configuration was done.
+        */
+       return ksz886x_config_mdix(phydev, phydev->mdix_ctrl);
+}
+
+static int ksz886x_mdix_update(struct phy_device *phydev)
+{
+       int ret;
+
+       ret = phy_read(phydev, MII_BMCR);
+       if (ret < 0)
+               return ret;
+
+       if (ret & KSZ886X_BMCR_DISABLE_AUTO_MDIX) {
+               if (ret & KSZ886X_BMCR_FORCE_MDI)
+                       phydev->mdix_ctrl = ETH_TP_MDI_X;
+               else
+                       phydev->mdix_ctrl = ETH_TP_MDI;
+       } else {
+               phydev->mdix_ctrl = ETH_TP_MDI_AUTO;
+       }
+
+       ret = phy_read(phydev, MII_KSZPHY_CTRL);
+       if (ret < 0)
+               return ret;
+
+       if (ret & KSZ886X_CTRL_MDIX_STAT)
+               phydev->mdix = ETH_TP_MDI;
+       else
+               phydev->mdix = ETH_TP_MDI_X;
+
+       return 0;
+}
+
+static int ksz886x_read_status(struct phy_device *phydev)
+{
+       int ret;
+
+       ret = ksz886x_mdix_update(phydev);
+       if (ret < 0)
+               return ret;
+
+       return genphy_read_status(phydev);
+}
+
 static int ksz886x_resume(struct phy_device *phydev)
 {
        int ret;
@@ -1366,6 +1465,8 @@ static struct phy_driver ksphy_driver[] = {
        .name           = "Micrel KSZ886X Switch",
        /* PHY_BASIC_FEATURES */
        .config_init    = kszphy_config_init,
+       .config_aneg    = ksz886x_config_aneg,
+       .read_status    = ksz886x_read_status,
        .suspend        = genphy_suspend,
        .resume         = ksz886x_resume,
 }, {
-- 
2.27.0

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