drivers: ethernet: phy: vsc8541: Add timeout on SW reset

The driver previously could enter an infinite loop if the PHY software
reset failed to complete, which could happen due to hardware reset
issues or MDIO bus problems. Add a timeout of 1000 iterations so we
report an error in this scenario rather than causing a lockup.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>

Author: robhancocksed

drivers/ethernet/phy/phy_microchip_vsc8541.c

@@ -134,6 +134,7 @@ static int phy_mc_vsc8541_reset(const struct device *dev)
 	const struct mc_vsc8541_config *cfg = dev->config;
 	int ret;
 	uint16_t reg = 0U;
+	int count = 0;
 
 #if DT_ANY_INST_HAS_PROP_STATUS_OKAY(reset_gpios)
 
@@ -197,8 +198,15 @@ static int phy_mc_vsc8541_reset(const struct device *dev)
 
 	/* wait for phy finished software reset */
 	do {
-		phy_mc_vsc8541_read(dev, MII_BMCR, &reg);
-	} while (reg & MII_BMCR_RESET);
+		ret = phy_mc_vsc8541_read(dev, MII_BMCR, &reg);
+		if (ret < 0) {
+			return ret;
+		}
+		if (count++ > 1000) {
+			LOG_ERR("phy reset timed out");
+			return -ETIMEDOUT;
+		}
+	} while ((reg & MII_BMCR_RESET) != 0U);
 
 	/* configure the RGMII clk delay */
 	reg = 0x0;