Fixed PHY: Add fixed_phy_change_carrier()

Drivers can use this as .ndo_change_carrier() to change carrier
via /sys/class/net/ethX/carrier.
Signed-off-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/fixed_phy.c

@@ -25,6 +25,7 @@
 #include <linux/gpio.h>
 #include <linux/seqlock.h>
 #include <linux/idr.h>
+#include <linux/netdevice.h>
 
 #include "swphy.h"
 
@@ -38,6 +39,7 @@ struct fixed_phy {
 	struct phy_device *phydev;
 	seqcount_t seqcount;
 	struct fixed_phy_status status;
+	bool no_carrier;
 	int (*link_update)(struct net_device *, struct fixed_phy_status *);
 	struct list_head node;
 	int link_gpio;
@@ -48,9 +50,28 @@ static struct fixed_mdio_bus platform_fmb = {
 	.phys = LIST_HEAD_INIT(platform_fmb.phys),
 };
 
+int fixed_phy_change_carrier(struct net_device *dev, bool new_carrier)
+{
+	struct fixed_mdio_bus *fmb = &platform_fmb;
+	struct phy_device *phydev = dev->phydev;
+	struct fixed_phy *fp;
+
+	if (!phydev || !phydev->mdio.bus)
+		return -EINVAL;
+
+	list_for_each_entry(fp, &fmb->phys, node) {
+		if (fp->addr == phydev->mdio.addr) {
+			fp->no_carrier = !new_carrier;
+			return 0;
+		}
+	}
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(fixed_phy_change_carrier);
+
 static void fixed_phy_update(struct fixed_phy *fp)
 {
-	if (gpio_is_valid(fp->link_gpio))
+	if (!fp->no_carrier && gpio_is_valid(fp->link_gpio))
 		fp->status.link = !!gpio_get_value_cansleep(fp->link_gpio);
 }
 
@@ -66,6 +87,7 @@ static int fixed_mdio_read(struct mii_bus *bus, int phy_addr, int reg_num)
 
 			do {
 				s = read_seqcount_begin(&fp->seqcount);
+				fp->status.link = !fp->no_carrier;
 				/* Issue callback if user registered it. */
 				if (fp->link_update) {
 					fp->link_update(fp->phydev->attached_dev,

include/linux/phy_fixed.h

@@ -13,6 +13,7 @@ struct fixed_phy_status {
 struct device_node;
 
 #if IS_ENABLED(CONFIG_FIXED_PHY)
+extern int fixed_phy_change_carrier(struct net_device *dev, bool new_carrier);
 extern int fixed_phy_add(unsigned int irq, int phy_id,
 			 struct fixed_phy_status *status,
 			 int link_gpio);
@@ -47,6 +48,10 @@ static inline int fixed_phy_set_link_update(struct phy_device *phydev,
 {
 	return -ENODEV;
 }
+static inline int fixed_phy_change_carrier(struct net_device *dev, bool new_carrier)
+{
+	return -EINVAL;
+}
 #endif /* CONFIG_FIXED_PHY */
 
 #endif /* __PHY_FIXED_H */