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From: Andre Werner <andre.werner@systec-electronic.com>
To: andrew@lunn.ch,
	hkallweit1@gmail.com,
	davem@davemloft.net,
	edumazet@google.com,
	kuba@kernel.org,
	pabeni@redhat.com
Cc: linux@armlinux.org.uk,
	netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Andre Werner <andre.werner@systec-electronic.com>
Subject: [PATCH] net: phy: adin1100: Fix nullptr exception for phy interrupts
Date: Thu, 18 Jan 2024 11:43:41 +0100
Message-ID: <20240118104341.10832-1-andre.werner@systec-electronic.com>
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If using ADIN1100 as an external phy, e.g. in combination with
"smsc95xx", we ran into nullptr exception by creating a link.

In our case the "smsc95xx" does not check for an available interrupt hand=
ler
on external phy driver to use poll instead of interrupts if no handler is
available. So we decide to implement a small handler in the phy driver
to support other MACs as well.

I update the driver to add an interrupt handler because libphy
does not check if their is a interrupt handler available either.

There are several interrupts maskable at the phy, but only link change in=
terrupts
are handled by the driver yet.

We tested the combination "smsc95xx" and "adin1100" with Linux Kernel 6.6=
9
and Linux Kernel 6.1.0, respectively.

Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
---
 drivers/net/phy/adin1100.c | 58 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/drivers/net/phy/adin1100.c b/drivers/net/phy/adin1100.c
index 7619d6185801..ed8a7e6250cf 100644
--- a/drivers/net/phy/adin1100.c
+++ b/drivers/net/phy/adin1100.c
@@ -18,6 +18,12 @@
 #define PHY_ID_ADIN1110				0x0283bc91
 #define PHY_ID_ADIN2111				0x0283bca1
=20
+#define ADIN_PHY_SUBSYS_IRQ_MASK		0x0021
+#define   ADIN_LINK_STAT_CHNG_IRQ_EN		BIT(1)
+
+#define ADIN_PHY_SUBSYS_IRQ_STATUS		0x0011
+#define   ADIN_LINK_STAT_CHNG			BIT(1)
+
 #define ADIN_FORCED_MODE			0x8000
 #define   ADIN_FORCED_MODE_EN			BIT(0)
=20
@@ -136,6 +142,56 @@ static int adin_config_aneg(struct phy_device *phyde=
v)
 	return genphy_c45_config_aneg(phydev);
 }
=20
+static int adin_phy_ack_intr(struct phy_device *phydev)
+{
+	/* Clear pending interrupts */
+	int rc =3D phy_read_mmd(phydev, MDIO_MMD_VEND2, ADIN_PHY_SUBSYS_IRQ_STA=
TUS);
+
+	return rc < 0 ? rc : 0;
+}
+
+static int adin_config_intr(struct phy_device *phydev)
+{
+	int ret, regval;
+
+	ret =3D adin_phy_ack_intr(phydev);
+
+	if (ret)
+		return ret;
+
+	regval =3D phy_read_mmd(phydev, MDIO_MMD_VEND2, ADIN_PHY_SUBSYS_IRQ_MAS=
K);
+	if (regval < 0)
+		return regval;
+
+	if (phydev->interrupts =3D=3D PHY_INTERRUPT_ENABLED)
+		regval |=3D ADIN_LINK_STAT_CHNG_IRQ_EN;
+	else
+		regval &=3D ~ADIN_LINK_STAT_CHNG_IRQ_EN;
+
+	ret =3D phy_write_mmd(phydev, MDIO_MMD_VEND2,
+			    ADIN_PHY_SUBSYS_IRQ_MASK,
+			    regval);
+	return ret;
+}
+
+static irqreturn_t adin_phy_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status =3D phy_read_mmd(phydev, MDIO_MMD_VEND2, ADIN_PHY_SUBSYS_IRQ=
_STATUS);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & ADIN_LINK_STAT_CHNG))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
 static int adin_set_powerdown_mode(struct phy_device *phydev, bool en)
 {
 	int ret;
@@ -275,6 +331,8 @@ static struct phy_driver adin_driver[] =3D {
 		.probe			=3D adin_probe,
 		.config_aneg		=3D adin_config_aneg,
 		.read_status		=3D adin_read_status,
+		.config_intr		=3D adin_config_intr,
+		.handle_interrupt	=3D adin_phy_handle_interrupt,
 		.set_loopback		=3D adin_set_loopback,
 		.suspend		=3D adin_suspend,
 		.resume			=3D adin_resume,
--=20
2.43.0