[PATCHv2 net] net: phy: marvell: undo WoL setup when Wake-on-LAN is disabled

[Rosen Penev <rosenp@gmail.com>]

Fully disabling Wake-on-LAN on the 88E1318S/88E1510 used to leave
the WoL interrupt enable bit (CSIER.WOL_EIE) set and LED[2]
configured as the INTn pin. A magic packet arriving after "wol d"
would still assert INTn, and a later "wol g" re-enabled WoL from a
dirty register state.

Fully disabling WoL clears CSIER.WOL_EIE on the copper page. The
LED[2]/INTn pin mux is disposed of only when this driver forced it to
the INTn function: the INTn enable and polarity bits read at arming
time are saved, and restored once all WoL options are cleared, so PHYs
serving the MAC interrupt, strap configs, or marvell,reg-init values
are never touched. The FORCE_INT bit is not set while disposing of the
pin: it holds the interrupt line asserted and turns the shared PHY
interrupt into a "nobody cared" IRQ storm when the PHY interrupt is in
use.

Fixes: 3871c3876f80 ("mv643xx_eth with 88E1318S: support Wake on LAN")
Assisted-by: LLM
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 v2: move to net with Fixes. Address phy_interrupt_is_valid issue.
 drivers/net/phy/marvell.c | 54 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
index f71cffa88406..64862f12eb42 100644
--- a/drivers/net/phy/marvell.c
+++ b/drivers/net/phy/marvell.c
@@ -354,6 +354,8 @@ struct marvell_priv {
 	u32 step;
 	s8 pair;
 	u8 vct_phase;
+	u16 wol_led_tcr;
+	bool wol_led_armed;
 };
 
 static int marvell_read_page(struct phy_device *phydev)
@@ -1969,6 +1971,7 @@ static void m88e1318_get_wol(struct phy_device *phydev,
 static int m88e1318_set_wol(struct phy_device *phydev,
 			    struct ethtool_wolinfo *wol)
 {
+	struct marvell_priv *priv = phydev->priv;
 	int err = 0, oldpage;
 
 	oldpage = phy_save_page(phydev);
@@ -2000,6 +2003,22 @@ static int m88e1318_set_wol(struct phy_device *phydev,
 		if (err < 0)
 			goto error;
 
+		/* Remember the LED[2]/INTn mux before forcing the pin to
+		 * INTn, so it can be restored when WoL is disabled again.
+		 * Only save it once, or a re-enable would overwrite the
+		 * value read before WoL was first armed.
+		 */
+		if (!priv->wol_led_armed) {
+			err = __phy_read(phydev, MII_88E1318S_PHY_LED_TCR);
+			if (err < 0)
+				goto error;
+
+			priv->wol_led_tcr = err &
+				(MII_88E1318S_PHY_LED_TCR_INTn_ENABLE |
+				 MII_88E1318S_PHY_LED_TCR_INT_ACTIVE_LOW);
+			priv->wol_led_armed = true;
+		}
+
 		/* Setup LED[2] as interrupt pin (active low) */
 		err = __phy_modify(phydev, MII_88E1318S_PHY_LED_TCR,
 				   MII_88E1318S_PHY_LED_TCR_FORCE_INT,
@@ -2074,6 +2093,41 @@ static int m88e1318_set_wol(struct phy_device *phydev,
 			goto error;
 	}
 
+	if (!(wol->wolopts & (WAKE_MAGIC | WAKE_PHY))) {
+		/* Fully disabled: undo the WoL interrupt setup done above,
+		 * so a later re-enable starts from a clean state. The
+		 * LED[2]/INTn pin mux is only touched when it was forced
+		 * to INTn here, and is restored to the value read at
+		 * arming time; PHYs serving the MAC interrupt, straps, or
+		 * marvell,reg-init values are left alone.
+		 */
+		err = marvell_write_page(phydev, MII_MARVELL_COPPER_PAGE);
+		if (err < 0)
+			goto error;
+
+		err = __phy_clear_bits(phydev, MII_88E1318S_PHY_CSIER,
+				       MII_88E1318S_PHY_CSIER_WOL_EIE);
+		if (err < 0)
+			goto error;
+
+		if (!priv->wol_led_armed)
+			goto error;
+
+		err = marvell_write_page(phydev, MII_MARVELL_LED_PAGE);
+		if (err < 0)
+			goto error;
+
+		err = __phy_modify(phydev, MII_88E1318S_PHY_LED_TCR,
+				   MII_88E1318S_PHY_LED_TCR_FORCE_INT |
+				   MII_88E1318S_PHY_LED_TCR_INTn_ENABLE |
+				   MII_88E1318S_PHY_LED_TCR_INT_ACTIVE_LOW,
+				   priv->wol_led_tcr);
+		if (err < 0)
+			goto error;
+
+		priv->wol_led_armed = false;
+	}
+
 error:
 	return phy_restore_page(phydev, oldpage, err);
 }
-- 
2.55.0