net: phy: provide phylib stubs for hardware timestamping operations

net/core/dev_ioctl.c (built-in code) will want to call phy_mii_ioctl()
for hardware timestamping purposes. This is not directly possible,
because phy_mii_ioctl() is a symbol provided under CONFIG_PHYLIB.

Do something similar to what was done in DSA in commit 5a17818682cf
("net: dsa: replace NETDEV_PRE_CHANGE_HWTSTAMP notifier with a stub"),
and arrange some indirect calls to phy_mii_ioctl() through a stub
structure containing function pointers, that's provided by phylib as
built-in even when CONFIG_PHYLIB=m, and which phy_init() populates at
runtime (module insertion).

Note: maybe the ownership of the ethtool_phy_ops singleton is backwards,
and the methods exposed by that should be later merged into phylib_stubs.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20230801142824.1772134-12-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index bdf00b2b2c1d..8aec8e83038c 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -456,6 +456,40 @@ int phy_do_ioctl_running(struct net_device *dev, struct ifreq *ifr, int cmd)
 EXPORT_SYMBOL(phy_do_ioctl_running);
 
 /**
+ * __phy_hwtstamp_get - Get hardware timestamping configuration from PHY
+ *
+ * @phydev: the PHY device structure
+ * @config: structure holding the timestamping configuration
+ *
+ * Query the PHY device for its current hardware timestamping configuration.
+ */
+int __phy_hwtstamp_get(struct phy_device *phydev,
+		       struct kernel_hwtstamp_config *config)
+{
+	if (!phydev)
+		return -ENODEV;
+
+	return phy_mii_ioctl(phydev, config->ifr, SIOCGHWTSTAMP);
+}
+
+/**
+ * __phy_hwtstamp_set - Modify PHY hardware timestamping configuration
+ *
+ * @phydev: the PHY device structure
+ * @config: structure holding the timestamping configuration
+ * @extack: netlink extended ack structure, for error reporting
+ */
+int __phy_hwtstamp_set(struct phy_device *phydev,
+		       struct kernel_hwtstamp_config *config,
+		       struct netlink_ext_ack *extack)
+{
+	if (!phydev)
+		return -ENODEV;
+
+	return phy_mii_ioctl(phydev, config->ifr, SIOCSHWTSTAMP);
+}
+
+/**
  * phy_queue_state_machine - Trigger the state machine to run soon
  *
  * @phydev: the phy_device struct