net: phy: Add general dummy stubs for MMD register access

BugLink: https://bugs.launchpad.net/bugs/1836654
[ Upstream commit 5df7af85ecd88e8b5f1f31d6456c3cf38a8bbdda ]

For some phy devices, even though they don't support the MMD extended
register access, it does have some side effect if we are trying to
read/write the MMD registers via indirect method. So introduce general
dummy stubs for MMD register access which these devices can use to avoid
such side effect.

Fixes: b6b5e8a69118 ("gianfar: Disable EEE autoneg by default")
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index a174d05a975226c22ff50b5085bc7689083ebfa6..fe76e2c4022affb1669c333056c3d9f077e8956b 100644 (file)
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1641,6 +1641,23 @@ int genphy_config_init(struct phy_device *phydev)
 }
 EXPORT_SYMBOL(genphy_config_init);
 
+/* This is used for the phy device which doesn't support the MMD extended
+ * register access, but it does have side effect when we are trying to access
+ * the MMD register via indirect method.
+ */
+int genphy_read_mmd_unsupported(struct phy_device *phdev, int devad, u16 regnum)
+{
+       return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL(genphy_read_mmd_unsupported);
+
+int genphy_write_mmd_unsupported(struct phy_device *phdev, int devnum,
+                                u16 regnum, u16 val)
+{
+       return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL(genphy_write_mmd_unsupported);
+
 int genphy_suspend(struct phy_device *phydev)
 {
        int value;

diff --git a/include/linux/phy.h b/include/linux/phy.h
index cf451a43486cf05ceaf0ae76a318831dc1ce6d63..1178c1695c3167d52d6b51c747b77a882ab960d8 100644 (file)
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -880,6 +880,10 @@ static inline int genphy_no_soft_reset(struct phy_device *phydev)
 {
        return 0;
 }
+int genphy_read_mmd_unsupported(struct phy_device *phdev, int devad,
+                               u16 regnum);
+int genphy_write_mmd_unsupported(struct phy_device *phdev, int devnum,
+                                u16 regnum, u16 val);
 
 /* Clause 45 PHY */
 int genphy_c45_restart_aneg(struct phy_device *phydev);