[PATCH net-next v3 6/8] net: phy: add calibration callbacks to phy_driver

[Romain Gantois]

The IPQESS integrated Ethernet switch found in the IPQ4019 SoC requires
calibration of the PHY link when its ports are brought up. This calibration
procedure requires knowledge of precise timings and vendor-specific
registers on both the PHY and MAC side.

The existing PHY abstraction layer does not allow coordinating this kind of
calibration operation between MAC drivers and PHY drivers. As a
consequence, PHY-specific calibration information has to be included in
Ethernet drivers, since it has to schedule the entire calibration procedure
on it's own.

Add two callbacks that extend the PHY abstraction layer to allow MAC
drivers to start and stop PHY calibration runs in a PHY-model-independent
manner.

Signed-off-by: Romain Gantois <romain.gantois at bootlin.com>
---
 include/linux/phy.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 3cc52826f18e..b1092b2ecee3 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1142,6 +1142,13 @@ struct phy_driver {
 	int (*led_hw_control_get)(struct phy_device *dev, u8 index,
 				  unsigned long *rules);
 
+	/* @calibration_start: Start calibrating the MAC-to-PHY link. */
+	int (*calibration_start)(struct phy_device *dev);
+
+	/* @calibration_start: Finalize MAC-to-PHY link calibration
+	 * and run tests. Returns 0 if the calibration tests are successful.
+	 */
+	int (*calibration_stop)(struct phy_device *dev);
 };
 #define to_phy_driver(d) container_of(to_mdio_common_driver(d),		\
 				      struct phy_driver, mdiodrv)
@@ -1770,6 +1777,27 @@ int phy_start_cable_test_tdr(struct phy_device *phydev,
 }
 #endif
 
+static inline
+int phy_start_calibration(struct phy_device *phydev)
+{
+	if (!(phydev->drv &&
+	      phydev->drv->calibration_start &&
+	      phydev->drv->calibration_stop))
+		return -EOPNOTSUPP;
+
+	return phydev->drv->calibration_start(phydev);
+}
+
+static inline
+int phy_stop_calibration(struct phy_device *phydev)
+{
+	if (!(phydev->drv &&
+	      phydev->drv->calibration_stop))
+		return -EOPNOTSUPP;
+
+	return phydev->drv->calibration_stop(phydev);
+}
+
 static inline void phy_device_reset(struct phy_device *phydev, int value)
 {
 	mdio_device_reset(&phydev->mdio, value);
-- 
2.42.0