net: wwan: make WWAN_PORT_MAX meaning less surprised

It is quite unusual when some value can not be equal to a defined range
max value. Also most subsystems defines FOO_TYPE_MAX as a maximum valid
value. So turn the WAN_PORT_MAX meaning from the number of supported
port types to the maximum valid port type.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/wwan_core.c

@@ -250,7 +250,7 @@ struct wwan_port *wwan_create_port(struct device *parent,
 	struct wwan_port *port;
 	int minor, err = -ENOMEM;
 
-	if (type >= WWAN_PORT_MAX || !ops)
+	if (type > WWAN_PORT_MAX || !ops)
 		return ERR_PTR(-EINVAL);
 
 	/* A port is always a child of a WWAN device, retrieve (allocate or

include/linux/wwan.h

@@ -15,17 +15,23 @@
  * @WWAN_PORT_QMI: Qcom modem/MSM interface for modem control
  * @WWAN_PORT_QCDM: Qcom Modem diagnostic interface
  * @WWAN_PORT_FIREHOSE: XML based command protocol
- * @WWAN_PORT_UNKNOWN: Unknown port type
- * @WWAN_PORT_MAX: Number of supported port types
+ *
+ * @WWAN_PORT_MAX: Highest supported port types
+ * @WWAN_PORT_UNKNOWN: Special value to indicate an unknown port type
+ * @__WWAN_PORT_MAX: Internal use
  */
 enum wwan_port_type {
 	WWAN_PORT_AT,
 	WWAN_PORT_MBIM,
 	WWAN_PORT_QMI,
 	WWAN_PORT_QCDM,
 	WWAN_PORT_FIREHOSE,
+
+	/* Add new port types above this line */
+
+	__WWAN_PORT_MAX,
+	WWAN_PORT_MAX = __WWAN_PORT_MAX - 1,
 	WWAN_PORT_UNKNOWN,
-	WWAN_PORT_MAX = WWAN_PORT_UNKNOWN,
 };
 
 struct wwan_port;