net: xpcs: add support for retrieving supported interface modes

Add a function to the xpcs driver to retrieve the supported PHY
interface modes, which can be used by drivers to fill in phylink's
supported_interfaces mask.

We validate the interface bit index to ensure that it fits within the
bitmap as xpcs lists PHY_INTERFACE_MODE_MAX in an entry.
Tested-by: Wong Vee Khee &lt;vee.khee.wong@linux.intel.com&gt; # Intel EHL            Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/pcs/pcs-xpcs.c

@@ -662,6 +662,20 @@ void xpcs_validate(struct dw_xpcs *xpcs, unsigned long *supported,
 }
 EXPORT_SYMBOL_GPL(xpcs_validate);
 
+void xpcs_get_interfaces(struct dw_xpcs *xpcs, unsigned long *interfaces)
+{
+	int i, j;
+
+	for (i = 0; i < DW_XPCS_INTERFACE_MAX; i++) {
+		const struct xpcs_compat *compat = &xpcs->id->compat[i];
+
+		for (j = 0; j < compat->num_interfaces; j++)
+			if (compat->interface[j] < PHY_INTERFACE_MODE_MAX)
+				__set_bit(compat->interface[j], interfaces);
+	}
+}
+EXPORT_SYMBOL_GPL(xpcs_get_interfaces);
+
 int xpcs_config_eee(struct dw_xpcs *xpcs, int mult_fact_100ns, int enable)
 {
 	int ret;

include/linux/pcs/pcs-xpcs.h

@@ -33,6 +33,7 @@ int xpcs_do_config(struct dw_xpcs *xpcs, phy_interface_t interface,
 		   unsigned int mode);
 void xpcs_validate(struct dw_xpcs *xpcs, unsigned long *supported,
 		   struct phylink_link_state *state);
+void xpcs_get_interfaces(struct dw_xpcs *xpcs, unsigned long *interfaces);
 int xpcs_config_eee(struct dw_xpcs *xpcs, int mult_fact_100ns,
 		    int enable);
 struct dw_xpcs *xpcs_create(struct mdio_device *mdiodev,