mdio: Add generic MDIO (clause 45) support functions

These roughly mirror many of the MII library functions and are based
on code from the sfc driver.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/Kconfig

@@ -2443,6 +2443,9 @@ menuconfig NETDEV_10000
 
 if NETDEV_10000
 
+config MDIO
+	tristate
+
 config CHELSIO_T1
         tristate "Chelsio 10Gb Ethernet support"
         depends on PCI

drivers/net/Makefile

@@ -95,6 +95,7 @@ obj-$(CONFIG_SH_ETH) += sh_eth.o
 #
 
 obj-$(CONFIG_MII) += mii.o
+obj-$(CONFIG_MDIO) += mdio.o
 obj-$(CONFIG_PHYLIB) += phy/
 
 obj-$(CONFIG_SUNDANCE) += sundance.o

include/linux/mdio.h

@@ -234,4 +234,70 @@ static inline __u16 mdio_phy_id_devad(int phy_id)
 	return phy_id & MDIO_PHY_ID_DEVAD;
 }
 
+#ifdef __KERNEL__ 
+
+/**
+ * struct mdio_if_info - Ethernet controller MDIO interface
+ * @prtad: PRTAD of the PHY (%MDIO_PRTAD_NONE if not present/unknown)
+ * @mmds: Mask of MMDs expected to be present in the PHY.  This must be
+ *	non-zero unless @prtad = %MDIO_PRTAD_NONE.
+ * @mode_support: MDIO modes supported.  If %MDIO_SUPPORTS_C22 is set then
+ *	MII register access will be passed through with @devad =
+ *	%MDIO_DEVAD_NONE.  If %MDIO_EMULATE_C22 is set then access to
+ *	commonly used clause 22 registers will be translated into
+ *	clause 45 registers.
+ * @dev: Net device structure
+ * @mdio_read: Register read function; returns value or negative error code
+ * @mdio_write: Register write function; returns 0 or negative error code
+ */
+struct mdio_if_info {
+	int prtad;
+	u32 __bitwise mmds;
+	unsigned mode_support;
+
+	struct net_device *dev;
+	int (*mdio_read)(struct net_device *dev, int prtad, int devad,
+			 u16 addr);
+	int (*mdio_write)(struct net_device *dev, int prtad, int devad,
+			  u16 addr, u16 val);
+};
+
+#define MDIO_PRTAD_NONE			(-1)
+#define MDIO_DEVAD_NONE			(-1)
+#define MDIO_SUPPORTS_C22		1
+#define MDIO_SUPPORTS_C45		2
+#define MDIO_EMULATE_C22		4
+
+struct ethtool_cmd;
+struct ethtool_pauseparam;
+extern int mdio45_probe(struct mdio_if_info *mdio, int prtad);
+extern int mdio_set_flag(const struct mdio_if_info *mdio,
+			 int prtad, int devad, u16 addr, int mask,
+			 bool sense);
+extern int mdio45_links_ok(const struct mdio_if_info *mdio, u32 mmds);
+extern int mdio45_nway_restart(const struct mdio_if_info *mdio);
+extern void mdio45_ethtool_gset_npage(const struct mdio_if_info *mdio,
+				      struct ethtool_cmd *ecmd,
+				      u32 npage_adv, u32 npage_lpa);
+
+/**
+ * mdio45_ethtool_gset - get settings for ETHTOOL_GSET
+ * @mdio: MDIO interface
+ * @ecmd: Ethtool request structure
+ *
+ * Since the CSRs for auto-negotiation using next pages are not fully
+ * standardised, this function does not attempt to decode them.  Use
+ * mdio45_ethtool_gset_npage() to specify advertisement bits from next
+ * pages.
+ */
+static inline void mdio45_ethtool_gset(const struct mdio_if_info *mdio,
+				       struct ethtool_cmd *ecmd)
+{
+	mdio45_ethtool_gset_npage(mdio, ecmd, 0, 0);
+}
+
+extern int mdio_mii_ioctl(const struct mdio_if_info *mdio,
+			  struct mii_ioctl_data *mii_data, int cmd);
+
+#endif /* __KERNEL__ */
 #endif /* __LINUX_MDIO_H__ */