From: Javen Xu <redacted>

Add a generic Clause 45 software reset helper. The helper sets the reset
bit in the PMA/PMD control register and waits until the bit is cleared by
hardware.

Reviewed-by: Nicolai Buchwitz <redacted>
Signed-off-by: Javen Xu <redacted>
---
Changes in v2:
 - no changes, new file

Changes in v3:
 - re-order function according to the order in phy-c45.c

Changes in v4:
 - no changes

Changes in v5:
 - no changes

Changes in v6:
 - increase timeout to 600ms

Changes in v7:
 - no changes
 
Changes in v8:
 - no changes
---
 drivers/net/phy/phy-c45.c | 22 ++++++++++++++++++++++
 include/linux/phy.h       |  1 +
 2 files changed, 23 insertions(+)

diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c
index 126951741428..60d044156a83 100644
--- a/drivers/net/phy/phy-c45.c
+++ b/drivers/net/phy/phy-c45.c

@@ -384,6 +384,28 @@ int genphy_c45_check_and_restart_aneg(struct phy_device *phydev, bool restart)
 }
 EXPORT_SYMBOL_GPL(genphy_c45_check_and_restart_aneg);
 
+/**
+ * genphy_c45_soft_reset - software reset the PHY via Clause 45 PMA/PMD control register
+ * @phydev: target phy_device struct
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int genphy_c45_soft_reset(struct phy_device *phydev)
+{
+	int ret, val;
+
+	ret = phy_set_bits_mmd(phydev, MDIO_MMD_PMAPMD, MDIO_CTRL1,
+			       MDIO_CTRL1_RESET);
+	if (ret < 0)
+		return ret;
+
+	return phy_read_mmd_poll_timeout(phydev, MDIO_MMD_PMAPMD,
+					 MDIO_CTRL1, val,
+					 !(val & MDIO_CTRL1_RESET),
+					 5000, 600000, true);
+}
+EXPORT_SYMBOL_GPL(genphy_c45_soft_reset);