The at803x family of devices are subjected to an errata that requires
hard-reseting the PHY upon link change.

That can only work if there's a physical reset line wired to the PHY,
which the driver checks by looking if there's a reset GPIO configured
for the MDIO device.

The reset may however be controlled through a reset controller, which
isn't accounted for in the errata handling.

Besides that, PHY drivers aren't expected to directly access the
mdiodev's resources directly, let's therefore wrap this with a phylib
helper, that uses a similar mdio helper to check for reset existence.

This was found in preparation for bus-level resource management for
better mdio scan support.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
drivers/net/phy/qcom/at803x.c | 2 +-
include/linux/mdio.h          | 5 +++++
include/linux/phy.h           | 5 +++++
3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/qcom/at803x.c b/drivers/net/phy/qcom/at803x.c
index ba4dc07752b6..6872dbf77856 100644
--- a/drivers/net/phy/qcom/at803x.c
+++ b/drivers/net/phy/qcom/at803x.c

@@ -537,7 +537,7 @@ static void at803x_link_change_notify(struct phy_device *phydev)

	 * in the FIFO. In such cases, the FIFO enters an error mode it
	 * cannot recover from by software.
	 */
-	if (phydev->state == PHY_NOLINK && phydev->mdio.reset_gpio) {
+	if (phydev->state == PHY_NOLINK && phy_device_has_reset(phydev)) {
		struct at803x_context context;

		at803x_context_save(phydev, &context);

diff --git a/include/linux/mdio.h b/include/linux/mdio.h
index 300805e66592..a7d9e3ae362a 100644
--- a/include/linux/mdio.h
+++ b/include/linux/mdio.h

@@ -86,6 +86,11 @@ static inline void *mdiodev_get_drvdata(struct mdio_device *mdio)

	return dev_get_drvdata(&mdio->dev);
}

+static inline bool mdiodev_has_reset(struct mdio_device *mdio)
+{
+	return (mdio->reset_gpio || mdio->reset_ctrl);
+}
+
void mdio_device_free(struct mdio_device *mdiodev);
struct mdio_device *mdio_device_create(struct mii_bus *bus, int addr);
int mdio_device_register(struct mdio_device *mdiodev);

diff --git a/include/linux/phy.h b/include/linux/phy.h
index fc680901275b..beff1d6fcc7c 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h

@@ -2231,6 +2231,11 @@ static inline void phy_device_reset(struct phy_device *phydev, int value)

	mdio_device_reset(&phydev->mdio, value);
}

+static inline bool phy_device_has_reset(struct phy_device *phydev)
+{
+	return mdiodev_has_reset(&phydev->mdio);
+}
+
#define phydev_err(_phydev, format, args...)	\
	dev_err(&_phydev->mdio.dev, format, ##args)