net: phy: add phy_query_inband()

Add a method to query the PHY's in-band capabilities for a PHY
interface mode. This can be used to determine for the specified
interface mode whether in-band signalling is supported, and whether
the PHY requires in-band signalling.

When not implemented, or the PHY driver doesn't report any modes
for the interface, LINK_INBAND_VALID will not be set. When set, the
remainder of the flags can be interpreted.

LINK_INBAND_POSSIBLE means that the device can be configured to use
or not use in-band signalling. Later patches may add support to
configure this at the PHY.

LINK_INBAND_REQUIRED means that the device uses in-band signalling
which can not be disabled.

When only LINK_INBAND_VALID has been set, this means that the device
does not support any in-band signalling, and can't be configured to
do so.

"Bypass" mode (where the device may be configured for in-band, but
may still bring the link up if there is no in-band received from the
link partner) is not considered in this patch.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 89fd2564cbad..ef8b4c9e346a 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -993,6 +993,27 @@ static int phy_check_link_status(struct phy_device *phydev)
 }
 
 /**
+ * phy_query_inband - query which in-band signalling modes are supported
+ * @phydev: a pointer to a &struct phy_device
+ * @interface: the interface mode for the PHY
+ *
+ * Returns zero if it is unknown what in-band signalling is supported by the
+ * PHY (e.g. because the PHY driver doesn't implement the method.) Otherwise,
+ * returns a bit mask of the LINK_INBAND_* values from
+ * &enum link_inband_signalling to describe which inband modes are supported
+ * for this interface mode.
+ */
+unsigned int phy_query_inband(struct phy_device *phydev,
+			      phy_interface_t interface)
+{
+	if (phydev->drv && phydev->drv->query_inband)
+		return phydev->drv->query_inband(phydev, interface);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(phy_query_inband);
+
+/**
  * _phy_start_aneg - start auto-negotiation for this PHY device
  * @phydev: the phy_device struct
  *