net: phy: tja11xx: execute cable test on link up

A typical 100Base-T1 link should be always connected. If the link is in
a shot or open state, it is a failure. In most cases, we won't be able
to automatically handle this issue, but we need to log it or notify user
(if possible).

With this patch, the cable will be tested on "ip l s dev .. up" attempt
and send ethnl notification to the user space.

This patch was tested with TJA1102 PHY and "ethtool --monitor" command.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/nxp-tja11xx.c

@@ -180,10 +180,43 @@ static int tja11xx_soft_reset(struct phy_device *phydev)
 	return genphy_soft_reset(phydev);
 }
 
+static int tja11xx_config_aneg_cable_test(struct phy_device *phydev)
+{
+	bool finished = false;
+	int ret;
+
+	if (phydev->link)
+		return 0;
+
+	if (!phydev->drv->cable_test_start ||
+	    !phydev->drv->cable_test_get_status)
+		return 0;
+
+	ret = ethnl_cable_test_alloc(phydev);
+	if (ret)
+		return ret;
+
+	ret = phydev->drv->cable_test_start(phydev);
+	if (ret)
+		return ret;
+
+	/* According to the documentation this test takes 100 usec */
+	usleep_range(100, 200);
+
+	ret = phydev->drv->cable_test_get_status(phydev, &finished);
+	if (ret)
+		return ret;
+
+	if (finished)
+		ethnl_cable_test_finished(phydev);
+
+	return 0;
+}
+
 static int tja11xx_config_aneg(struct phy_device *phydev)
 {
+	int ret, changed = 0;
 	u16 ctl = 0;
-	int ret;
 
 	switch (phydev->master_slave_set) {
 	case MASTER_SLAVE_CFG_MASTER_FORCE:
@@ -193,17 +226,22 @@ static int tja11xx_config_aneg(struct phy_device *phydev)
 		break;
 	case MASTER_SLAVE_CFG_UNKNOWN:
 	case MASTER_SLAVE_CFG_UNSUPPORTED:
-		return 0;
+		goto do_test;
 	default:
 		phydev_warn(phydev, "Unsupported Master/Slave mode\n");
 		return -ENOTSUPP;
 	}
 
-	ret = phy_modify_changed(phydev, MII_CFG1, MII_CFG1_MASTER_SLAVE, ctl);
-	if (ret < 0)
+	changed = phy_modify_changed(phydev, MII_CFG1, MII_CFG1_MASTER_SLAVE, ctl);
+	if (changed < 0)
+		return changed;
+
+do_test:
+	ret = tja11xx_config_aneg_cable_test(phydev);
+	if (ret)
 		return ret;
 
-	return __genphy_config_aneg(phydev, ret);
+	return __genphy_config_aneg(phydev, changed);
 }
 
 static int tja11xx_config_init(struct phy_device *phydev)