phy: add hwtstamp_get callback to phy drivers

PHY devices had lack of hwtstamp_get callback even though most of them
are tracking configuration info. Introduce new call back to
mii_timestamper.

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20251124181151.277256-3-vadim.fedorenko@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit f467777)

Author: Vadim Fedorenko

drivers/net/phy/phy.c

@@ -476,6 +476,9 @@ int __phy_hwtstamp_get(struct phy_device *phydev,
 	if (!phydev)
 		return -ENODEV;
 
+	if (phydev->mii_ts && phydev->mii_ts->hwtstamp_get)
+		return phydev->mii_ts->hwtstamp_get(phydev->mii_ts, config);
+
 	return -EOPNOTSUPP;
 }
 

include/linux/mii_timestamper.h

@@ -29,6 +29,8 @@ struct phy_device;
  *
  * @hwtstamp:	Handles SIOCSHWTSTAMP ioctl for hardware time stamping.
  *
+ * @hwtstamp_get: Handles SIOCGHWTSTAMP ioctl for hardware time stamping.
+ *
  * @link_state: Allows the device to respond to changes in the link
  *		state.  The caller invokes this function while holding
  *		the phy_device mutex.
@@ -55,6 +57,9 @@ struct mii_timestamper {
 			 struct kernel_hwtstamp_config *kernel_config,
 			 struct netlink_ext_ack *extack);
 
+	int  (*hwtstamp_get)(struct mii_timestamper *mii_ts,
+			     struct kernel_hwtstamp_config *kernel_config);
+
 	void (*link_state)(struct mii_timestamper *mii_ts,
 			   struct phy_device *phydev);
 

net/core/dev_ioctl.c

@@ -249,10 +249,11 @@ int net_hwtstamp_validate(const struct kernel_hwtstamp_config *cfg)
  *
  * Helper for calling the default hardware provider timestamping.
  *
- * Note: phy_mii_ioctl() only handles SIOCSHWTSTAMP (not SIOCGHWTSTAMP), and
- * there only exists a phydev->mii_ts->hwtstamp() method. So this will return
- * -EOPNOTSUPP for phylib for now, which is still more accurate than letting
- * the netdev handle the GET request.
+ * Note: phy_mii_ioctl() only handles SIOCSHWTSTAMP (not SIOCGHWTSTAMP), but
+ * phydev->mii_ts has both hwtstamp_get() and hwtstamp_set() methods. So this
+ * will return -EOPNOTSUPP for phylib only if hwtstamp_get() is not
+ * implemented for now, which is still more accurate than letting the netdev
+ * handle the GET request.
  */
 int dev_get_hwtstamp_phylib(struct net_device *dev,
 			    struct kernel_hwtstamp_config *cfg)