Re: [PATCH net-next 1/2] net: usb: qmi_wwan: add qmap id sysfs file for qmimux interfaces

Add qmimux interface sysfs file qmap/mux_id to show qmap id set
during the interface creation, in order to provide a method for
userspace to associate QMI control channels to network interfaces.

Signed-off-by: Daniele Palmas <redacted>
---
 drivers/net/usb/qmi_wwan.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
index 7ea113f51074..9b85e2ed4760 100644
--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c

@@ -218,6 +218,31 @@ static int qmimux_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 	return 1;
 }
 
+static ssize_t mux_id_show(struct device *d, struct device_attribute *attr, char *buf)
+{
+	struct net_device *dev = to_net_dev(d);
+	struct qmimux_priv *priv;
+	ssize_t count = 0;
+
+	priv = netdev_priv(dev);
+	count += scnprintf(&buf[count], PAGE_SIZE - count,
+			   "0x%02x\n", priv->mux_id);