thunderbolt: Block reads and writes if switch is unplugged

If switch is already disconnected there is no point sending it commands
and waiting for timeout. Instead in that case return error immediately.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/tb.h

@@ -277,6 +277,8 @@ static inline struct tb_port *tb_port_at(u64 route, struct tb_switch *sw)
 static inline int tb_sw_read(struct tb_switch *sw, void *buffer,
 			     enum tb_cfg_space space, u32 offset, u32 length)
 {
+	if (sw->is_unplugged)
+		return -ENODEV;
 	return tb_cfg_read(sw->tb->ctl,
 			   buffer,
 			   tb_route(sw),
@@ -289,6 +291,8 @@ static inline int tb_sw_read(struct tb_switch *sw, void *buffer,
 static inline int tb_sw_write(struct tb_switch *sw, void *buffer,
 			      enum tb_cfg_space space, u32 offset, u32 length)
 {
+	if (sw->is_unplugged)
+		return -ENODEV;
 	return tb_cfg_write(sw->tb->ctl,
 			    buffer,
 			    tb_route(sw),
@@ -301,6 +305,8 @@ static inline int tb_sw_write(struct tb_switch *sw, void *buffer,
 static inline int tb_port_read(struct tb_port *port, void *buffer,
 			       enum tb_cfg_space space, u32 offset, u32 length)
 {
+	if (port->sw->is_unplugged)
+		return -ENODEV;
 	return tb_cfg_read(port->sw->tb->ctl,
 			   buffer,
 			   tb_route(port->sw),
@@ -313,6 +319,8 @@ static inline int tb_port_read(struct tb_port *port, void *buffer,
 static inline int tb_port_write(struct tb_port *port, const void *buffer,
 				enum tb_cfg_space space, u32 offset, u32 length)
 {
+	if (port->sw->is_unplugged)
+		return -ENODEV;
 	return tb_cfg_write(port->sw->tb->ctl,
 			    buffer,
 			    tb_route(port->sw),