From 809ff97a677ff85dfb7ce2b63be261d1633dcf29 Mon Sep 17 00:00:00 2001
From: Alexandru Tachici <alexandru.tachici@analog.com>
Date: Tue, 15 Nov 2022 13:44:34 +0200
Subject: [PATCH] net: usb: smsc95xx: fix external PHY reset
Git-commit: 809ff97a677ff85dfb7ce2b63be261d1633dcf29
References: git-fixes
Patch-mainline: v6.1-rc6

An external PHY needs settling time after power up or reset.
In the bind() function an mdio bus is registered. If at this point
the external PHY is still initialising, no valid PHY ID will be
read and on phy_find_first() the bind() function will fail.

If an external PHY is present, wait the maximum time specified
in 802.3 45.2.7.1.1.

Fixes: 05b35e7eb9a1 ("smsc95xx: add phylib support")
Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20221115114434.9991-2-alexandru.tachici@analog.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/net/usb/smsc95xx.c |   46 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 42 insertions(+), 4 deletions(-)

--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -59,6 +59,7 @@ struct smsc95xx_priv {
 	spinlock_t mac_cr_lock;
 	u8 features;
 	u8 suspend_flags;
+	bool is_internal_phy;
 	struct mii_bus *mdiobus;
 	struct phy_device *phydev;
 };
@@ -283,6 +284,43 @@ static void smsc95xx_mdio_write_nopm(str
 	__smsc95xx_mdio_write(dev, pdata->phydev->mdio.addr, idx, regval, 1);
 }
 
+static int smsc95xx_mdiobus_reset(struct mii_bus *bus)
+{
+	struct smsc95xx_priv *pdata;
+	struct usbnet *dev;
+	u32 val;
+	int ret;
+
+	dev = bus->priv;
+	pdata = dev->driver_priv;
+
+	if (pdata->is_internal_phy)
+		return 0;
+
+	mutex_lock(&dev->phy_mutex);
+
+	ret = smsc95xx_read_reg(dev, PM_CTRL, &val);
+	if (ret < 0)
+		goto reset_out;
+
+	val |= PM_CTL_PHY_RST_;
+
+	ret = smsc95xx_write_reg(dev, PM_CTRL, val);
+	if (ret < 0)
+		goto reset_out;
+
+	/* Driver has no knowledge at this point about the external PHY.
+	 * The 802.3 specifies that the reset process shall
+	 * be completed within 0.5 s.
+	 */
+	fsleep(500000);
+
+reset_out:
+	mutex_unlock(&dev->phy_mutex);
+
+	return 0;
+}
+
 static int smsc95xx_mdiobus_read(struct mii_bus *bus, int phy_id, int idx)
 {
 	struct usbnet *dev = bus->priv;
@@ -1055,7 +1093,6 @@ static void smsc95xx_handle_link_change(
 static int smsc95xx_bind(struct usbnet *dev, struct usb_interface *intf)
 {
 	struct smsc95xx_priv *pdata;
-	bool is_internal_phy;
 	u32 val;
 	int ret;
 
@@ -1107,13 +1144,14 @@ static int smsc95xx_bind(struct usbnet *
 	if (ret < 0)
 		goto free_mdio;
 
-	is_internal_phy = !(val & HW_CFG_PSEL_);
-	if (is_internal_phy)
+	pdata->is_internal_phy = !(val & HW_CFG_PSEL_);
+	if (pdata->is_internal_phy)
 		pdata->mdiobus->phy_mask = ~(1u << SMSC95XX_INTERNAL_PHY_ID);
 
 	pdata->mdiobus->priv = dev;
 	pdata->mdiobus->read = smsc95xx_mdiobus_read;
 	pdata->mdiobus->write = smsc95xx_mdiobus_write;
+	pdata->mdiobus->reset = smsc95xx_mdiobus_reset;
 	pdata->mdiobus->name = "smsc95xx-mdiobus";
 	pdata->mdiobus->parent = &dev->udev->dev;
 
@@ -1133,7 +1171,7 @@ static int smsc95xx_bind(struct usbnet *
 		goto unregister_mdio;
 	}
 
-	pdata->phydev->is_internal = is_internal_phy;
+	pdata->phydev->is_internal = pdata->is_internal_phy;
 
 	/* detect device revision as different features may be available */
 	ret = smsc95xx_read_reg(dev, ID_REV, &val);