net: phy: Add phy loopback support in net phy framework

This patch add set_loopback in phy_driver, which is used by MAC
driver to enable or disable phy loopback. it also add a generic
genphy_loopback function, which use BMCR loopback bit to enable
or disable loopback.
Signed-off-by: Lin Yun Sheng <linyunsheng@huawei.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/marvell.c

@@ -2171,6 +2171,7 @@ static struct phy_driver marvell_drivers[] = {
 		.get_sset_count = marvell_get_sset_count,
 		.get_strings = marvell_get_strings,
 		.get_stats = marvell_get_stats,
+		.set_loopback = genphy_loopback,
 	},
 	{
 		.phy_id = MARVELL_PHY_ID_88E1540,

drivers/net/phy/phy_device.c

@@ -1136,6 +1136,39 @@ int phy_resume(struct phy_device *phydev)
 }
 EXPORT_SYMBOL(phy_resume);
 
+int phy_loopback(struct phy_device *phydev, bool enable)
+{
+	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
+	int ret = 0;
+
+	mutex_lock(&phydev->lock);
+
+	if (enable && phydev->loopback_enabled) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (!enable && !phydev->loopback_enabled) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (phydev->drv && phydrv->set_loopback)
+		ret = phydrv->set_loopback(phydev, enable);
+	else
+		ret = -EOPNOTSUPP;
+
+	if (ret)
+		goto out;
+
+	phydev->loopback_enabled = enable;
+
+out:
+	mutex_unlock(&phydev->lock);
+	return ret;
+}
+EXPORT_SYMBOL(phy_loopback);
+
 /* Generic PHY support and helper functions */
 
 /**
@@ -1584,6 +1617,23 @@ int genphy_resume(struct phy_device *phydev)
 }
 EXPORT_SYMBOL(genphy_resume);
 
+int genphy_loopback(struct phy_device *phydev, bool enable)
+{
+	int value;
+
+	value = phy_read(phydev, MII_BMCR);
+	if (value < 0)
+		return value;
+
+	if (enable)
+		value |= BMCR_LOOPBACK;
+	else
+		value &= ~BMCR_LOOPBACK;
+
+	return phy_write(phydev, MII_BMCR, value);
+}
+EXPORT_SYMBOL(genphy_loopback);
+
 static int __set_phy_supported(struct phy_device *phydev, u32 max_speed)
 {
 	/* The default values for phydev->supported are provided by the PHY
@@ -1829,6 +1879,7 @@ static struct phy_driver genphy_driver = {
 	.read_status	= genphy_read_status,
 	.suspend	= genphy_suspend,
 	.resume		= genphy_resume,
+	.set_loopback   = genphy_loopback,
 };
 
 static int __init phy_init(void)

include/linux/phy.h

@@ -372,6 +372,7 @@ struct phy_c45_device_ids {
  * has_fixups: Set to true if this phy has fixups/quirks.
  * suspended: Set to true if this phy has been suspended successfully.
  * sysfs_links: Internal boolean tracking sysfs symbolic links setup/removal.
+ * loopback_enabled: Set true if this phy has been loopbacked successfully.
  * state: state of the PHY for management purposes
  * dev_flags: Device-specific flags used by the PHY driver.
  * link_timeout: The number of timer firings to wait before the
@@ -409,6 +410,7 @@ struct phy_device {
 	bool has_fixups;
 	bool suspended;
 	bool sysfs_links;
+	bool loopback_enabled;
 
 	enum phy_state state;
 
@@ -648,6 +650,7 @@ struct phy_driver {
 	int (*set_tunable)(struct phy_device *dev,
 			    struct ethtool_tunable *tuna,
 			    const void *data);
+	int (*set_loopback)(struct phy_device *dev, bool enable);
 };
 #define to_phy_driver(d) container_of(to_mdio_common_driver(d),		\
 				      struct phy_driver, mdiodrv)
@@ -793,6 +796,7 @@ void phy_device_remove(struct phy_device *phydev);
 int phy_init_hw(struct phy_device *phydev);
 int phy_suspend(struct phy_device *phydev);
 int phy_resume(struct phy_device *phydev);
+int phy_loopback(struct phy_device *phydev, bool enable);
 struct phy_device *phy_attach(struct net_device *dev, const char *bus_id,
 			      phy_interface_t interface);
 struct phy_device *phy_find_first(struct mii_bus *bus);
@@ -847,6 +851,7 @@ int genphy_update_link(struct phy_device *phydev);
 int genphy_read_status(struct phy_device *phydev);
 int genphy_suspend(struct phy_device *phydev);
 int genphy_resume(struct phy_device *phydev);
+int genphy_loopback(struct phy_device *phydev, bool enable);
 int genphy_soft_reset(struct phy_device *phydev);
 static inline int genphy_no_soft_reset(struct phy_device *phydev)
 {