From: Javen Xu <javen_xu@realsil.com.cn>

Add a generic helper to configure forced master/slave mode for Clause 45
PHYs using the 10GBASE-T AN control register.

Signed-off-by: Javen Xu <javen_xu@realsil.com.cn>
---
Changes in v2:
 - no changes, new file

Changes in v3:
 - re-order function according to the order in phy-c45.c
 - add kernel-doc about return value
 - add MASTER_SLAVE_CFG_MASTER_PREFERRED,
   MASTER_SLAVE_CFG_SLAVE_PREFERRED, MASTER_SLAVE_CFG_UNKNOWN,
   MASTER_SLAVE_CFG_UNSUPPORTED, MASTER_SLAVE_CFG_SLAVE_PREFERRED cfg
   
Changes in v4:
 - no changes
---
 drivers/net/phy/phy-c45.c | 42 +++++++++++++++++++++++++++++++++++++++
 include/linux/phy.h       |  1 +
 include/uapi/linux/mdio.h |  3 +++
 3 files changed, 46 insertions(+)

diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c
index d8a83179ec40..28cb173ff7aa 100644
--- a/drivers/net/phy/phy-c45.c
+++ b/drivers/net/phy/phy-c45.c
@@ -406,6 +406,48 @@ int genphy_c45_soft_reset(struct phy_device *phydev)
 }
 EXPORT_SYMBOL_GPL(genphy_c45_soft_reset);
 
+/**
+ * genphy_c45_an_setup_master_slave - Configure Master/Slave setting for C45 PHYs
+ * @phydev: target phy_device struct
+ *
+ * Description: Configure the forced or preferred Master/Slave role
+ * 10GBASE-T control register (MMD 7, Register 0x0020) according to
+ * IEEE 802.3 standards.
+ *
+ * Returns negative errno code on failure, 0 if Master/Slave didn't change,
+ * or 1 if Master/Slave modes changed.
+ */
+int genphy_c45_an_setup_master_slave(struct phy_device *phydev)
+{
+	u16 ctl = 0;
+
+	switch (phydev->master_slave_set) {
+	case MASTER_SLAVE_CFG_MASTER_PREFERRED:
+		ctl = MDIO_AN_10GBT_CTRL_MS_PORT_TYPE;
+		break;
+	case MASTER_SLAVE_CFG_SLAVE_PREFERRED:
+		break;
+	case MASTER_SLAVE_CFG_MASTER_FORCE:
+		ctl = MDIO_AN_10GBT_CTRL_MS_ENABLE | MDIO_AN_10GBT_CTRL_MS_VALUE;
+		break;
+	case MASTER_SLAVE_CFG_SLAVE_FORCE:
+		ctl = MDIO_AN_10GBT_CTRL_MS_ENABLE;
+		break;
+	case MASTER_SLAVE_CFG_UNKNOWN:
+	case MASTER_SLAVE_CFG_UNSUPPORTED:
+		return 0;
+	default:
+		phydev_warn(phydev, "Unsupported Master/Slave mode\n");
+		return -EOPNOTSUPP;
+	}
+
+	return phy_modify_mmd_changed(phydev, MDIO_MMD_AN, MDIO_AN_10GBT_CTRL,
+				      MDIO_AN_10GBT_CTRL_MS_ENABLE |
+				      MDIO_AN_10GBT_CTRL_MS_VALUE |
+				      MDIO_AN_10GBT_CTRL_MS_PORT_TYPE, ctl);
+}
+EXPORT_SYMBOL_GPL(genphy_c45_an_setup_master_slave);
+
 /**
  * genphy_c45_aneg_done - return auto-negotiation complete status
  * @phydev: target phy_device struct
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 25a66320df56..a46f4d9a6155 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -2310,6 +2310,7 @@ int genphy_c37_read_status(struct phy_device *phydev, bool *changed);
 int genphy_c45_restart_aneg(struct phy_device *phydev);
 int genphy_c45_check_and_restart_aneg(struct phy_device *phydev, bool restart);
 int genphy_c45_soft_reset(struct phy_device *phydev);
+int genphy_c45_an_setup_master_slave(struct phy_device *phydev);
 int genphy_c45_aneg_done(struct phy_device *phydev);
 int genphy_c45_read_link(struct phy_device *phydev);
 int genphy_c45_read_lpa(struct phy_device *phydev);
diff --git a/include/uapi/linux/mdio.h b/include/uapi/linux/mdio.h
index b2541c948fc1..ffca03fd82c9 100644
--- a/include/uapi/linux/mdio.h
+++ b/include/uapi/linux/mdio.h
@@ -332,6 +332,9 @@
 #define MDIO_AN_10GBT_CTRL_ADV2_5G	0x0080	/* Advertise 2.5GBASE-T */
 #define MDIO_AN_10GBT_CTRL_ADV5G	0x0100	/* Advertise 5GBASE-T */
 #define MDIO_AN_10GBT_CTRL_ADV10G	0x1000	/* Advertise 10GBASE-T */
+#define MDIO_AN_10GBT_CTRL_MS_ENABLE	0x8000	/* Master/slave manual config enable */
+#define MDIO_AN_10GBT_CTRL_MS_VALUE	0x4000	/* Master/slave config value (1=Master) */
+#define MDIO_AN_10GBT_CTRL_MS_PORT_TYPE	0x2000	/* Master Preferred Type */
 
 /* AN 10GBASE-T status register. */
 #define MDIO_AN_10GBT_STAT_LP2_5G	0x0020  /* LP is 2.5GBT capable */
-- 
2.43.0