---
v2->v3:
-changed "sw" string to "switch" to avoid confusion
v1->v2:
-no change
---
 net/core/net-sysfs.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 26c46f4..9993412 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c

@@ -12,6 +12,7 @@
 #include <linux/capability.h>
 #include <linux/kernel.h>
 #include <linux/netdevice.h>
+#include <net/switchdev.h>
 #include <linux/if_arp.h>
 #include <linux/slab.h>
 #include <linux/nsproxy.h>

@@ -416,6 +417,28 @@ static ssize_t phys_port_id_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(phys_port_id);
 
+static ssize_t phys_switch_id_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct net_device *netdev = to_net_dev(dev);
+	ssize_t ret = -EINVAL;
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	if (dev_isalive(netdev)) {
+		struct netdev_phys_item_id ppid;
+
+		ret = netdev_switch_parent_id_get(netdev, &ppid);
+		if (!ret)
+			ret = sprintf(buf, "%*phN\n", ppid.id_len, ppid.id);
+	}
+	rtnl_unlock();
+
+	return ret;
+}
+static DEVICE_ATTR_RO(phys_switch_id);
+
 static struct attribute *net_class_attrs[] = {
 	&dev_attr_netdev_group.attr,
 	&dev_attr_type.attr,

@@ -441,6 +464,7 @@ static struct attribute *net_class_attrs[] = {
 	&dev_attr_tx_queue_len.attr,
 	&dev_attr_gro_flush_timeout.attr,
 	&dev_attr_phys_port_id.attr,
+	&dev_attr_phys_switch_id.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(net_class);