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>

diff --git a/MAINTAINERS b/MAINTAINERS
index c4f95a9d03b9ef8501bf205ccb07639cfab85ffc..069e176d607a4c46946c4786f108526d2ea80761 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7752,6 +7752,7 @@ F:        include/linux/mii.h
 F:     include/linux/of_net.h
 F:     include/linux/phy.h
 F:     include/linux/phy_fixed.h
+F:     include/linux/phylib_stubs.h
 F:     include/linux/platform_data/mdio-bcm-unimac.h
 F:     include/linux/platform_data/mdio-gpio.h
 F:     include/trace/events/mdio.h

diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 35142780fc9daf1ffa5d1082cdac5f6fba2dbc5d..c945ed9bd14b3928d6aa161b925a075fd90e5e9b 100644 (file)
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -14,6 +14,8 @@ endif
 # dedicated loadable module, so we bundle them all together into libphy.ko
 ifdef CONFIG_PHYLIB
 libphy-y                       += $(mdio-bus-y)
+# the stubs are built-in whenever PHYLIB is built-in or module
+obj-y                          += stubs.o
 else
 obj-$(CONFIG_MDIO_DEVICE)      += mdio-bus.o
 endif

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index bdf00b2b2c1dc3ea0760d02476568b1398b7508c..8aec8e83038c50cbc7d9f8b13e2db04fa426bdf8 100644 (file)
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -455,6 +455,40 @@ 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
  *

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 98b8ac28e5a1041e8bc8aff766957b6730a1fd98..e19c4fee8d229a731d003527155bada4bb4bd777 100644 (file)
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -27,6 +27,7 @@
 #include <linux/of.h>
 #include <linux/netdevice.h>
 #include <linux/phy.h>
+#include <linux/phylib_stubs.h>
 #include <linux/phy_led_triggers.h>
 #include <linux/pse-pd/pse.h>
 #include <linux/property.h>
@@ -3448,12 +3449,28 @@ static const struct ethtool_phy_ops phy_ethtool_phy_ops = {
        .start_cable_test_tdr   = phy_start_cable_test_tdr,
 };
 
+static const struct phylib_stubs __phylib_stubs = {
+       .hwtstamp_get = __phy_hwtstamp_get,
+       .hwtstamp_set = __phy_hwtstamp_set,
+};
+
+static void phylib_register_stubs(void)
+{
+       phylib_stubs = &__phylib_stubs;
+}
+
+static void phylib_unregister_stubs(void)
+{
+       phylib_stubs = NULL;
+}
+
 static int __init phy_init(void)
 {
        int rc;
 
        rtnl_lock();
        ethtool_set_ethtool_phy_ops(&phy_ethtool_phy_ops);
+       phylib_register_stubs();
        rtnl_unlock();
 
        rc = mdio_bus_init();
@@ -3478,6 +3495,7 @@ static int __init phy_init(void)
        mdio_bus_exit();
 err_ethtool_phy_ops:
        rtnl_lock();
+       phylib_unregister_stubs();
        ethtool_set_ethtool_phy_ops(NULL);
        rtnl_unlock();
 
@@ -3490,6 +3508,7 @@ static void __exit phy_exit(void)
        phy_driver_unregister(&genphy_driver);
        mdio_bus_exit();
        rtnl_lock();
+       phylib_unregister_stubs();
        ethtool_set_ethtool_phy_ops(NULL);
        rtnl_unlock();
 }

diff --git a/drivers/net/phy/stubs.c b/drivers/net/phy/stubs.c
new file mode 100644 (file)
index 0000000..cfb9f27
--- /dev/null
+++ b/drivers/net/phy/stubs.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Stubs for PHY library functionality called by the core network stack.
+ * These are necessary because CONFIG_PHYLIB can be a module, and built-in
+ * code cannot directly call symbols exported by modules.
+ */
+#include <linux/phylib_stubs.h>
+
+const struct phylib_stubs *phylib_stubs;
+EXPORT_SYMBOL_GPL(phylib_stubs);

diff --git a/include/linux/phy.h b/include/linux/phy.h
index b254848a9c99a6060d04fc9d255fe8b22eb90a09..ba08b0e6027988e6a2cb32f90519836260f6dfcb 100644 (file)
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -298,6 +298,7 @@ static inline const char *phy_modes(phy_interface_t interface)
 #define MII_BUS_ID_SIZE        61
 
 struct device;
+struct kernel_hwtstamp_config;
 struct phylink;
 struct sfp_bus;
 struct sfp_upstream_ops;
@@ -1955,6 +1956,12 @@ int phy_ethtool_set_plca_cfg(struct phy_device *phydev,
 int phy_ethtool_get_plca_status(struct phy_device *phydev,
                                struct phy_plca_status *plca_st);
 
+int __phy_hwtstamp_get(struct phy_device *phydev,
+                      struct kernel_hwtstamp_config *config);
+int __phy_hwtstamp_set(struct phy_device *phydev,
+                      struct kernel_hwtstamp_config *config,
+                      struct netlink_ext_ack *extack);
+
 static inline int phy_package_read(struct phy_device *phydev, u32 regnum)
 {
        struct phy_package_shared *shared = phydev->shared;

diff --git a/include/linux/phylib_stubs.h b/include/linux/phylib_stubs.h
new file mode 100644 (file)
index 0000000..1279f48
--- /dev/null
+++ b/include/linux/phylib_stubs.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Stubs for the Network PHY library
+ */
+
+#include <linux/rtnetlink.h>
+
+struct kernel_hwtstamp_config;
+struct netlink_ext_ack;
+struct phy_device;
+
+#if IS_ENABLED(CONFIG_PHYLIB)
+
+extern const struct phylib_stubs *phylib_stubs;
+
+struct phylib_stubs {
+       int (*hwtstamp_get)(struct phy_device *phydev,
+                           struct kernel_hwtstamp_config *config);
+       int (*hwtstamp_set)(struct phy_device *phydev,
+                           struct kernel_hwtstamp_config *config,
+                           struct netlink_ext_ack *extack);
+};
+
+static inline int phy_hwtstamp_get(struct phy_device *phydev,
+                                  struct kernel_hwtstamp_config *config)
+{
+       /* phylib_register_stubs() and phylib_unregister_stubs()
+        * also run under rtnl_lock().
+        */
+       ASSERT_RTNL();
+
+       if (!phylib_stubs)
+               return -EOPNOTSUPP;
+
+       return phylib_stubs->hwtstamp_get(phydev, config);
+}
+
+static inline int phy_hwtstamp_set(struct phy_device *phydev,
+                                  struct kernel_hwtstamp_config *config,
+                                  struct netlink_ext_ack *extack)
+{
+       /* phylib_register_stubs() and phylib_unregister_stubs()
+        * also run under rtnl_lock().
+        */
+       ASSERT_RTNL();
+
+       if (!phylib_stubs)
+               return -EOPNOTSUPP;
+
+       return phylib_stubs->hwtstamp_set(phydev, config, extack);
+}
+
+#else
+
+static inline int phy_hwtstamp_get(struct phy_device *phydev,
+                                  struct kernel_hwtstamp_config *config)
+{
+       return -EOPNOTSUPP;
+}
+
+static inline int phy_hwtstamp_set(struct phy_device *phydev,
+                                  struct kernel_hwtstamp_config *config,
+                                  struct netlink_ext_ack *extack)
+{
+       return -EOPNOTSUPP;
+}
+
+#endif