thunderbolt: Split setting link width and lane bonding into own functions

When bonding lanes over XDomain the host that has "higher" UUID triggers
link re-train for bonding, and the host that has "lower" UUID just waits
for this to happen. To support this split setting the link width and
triggering the actual bonding a separate functions that can be called as
needed.

While there remove duplicated empty line in the kernel-doc comment of
tb_port_lane_bonding_disable().
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/switch.c

@@ -999,7 +999,17 @@ static bool tb_port_is_width_supported(struct tb_port *port, int width)
 	return !!(widths & width);
 }
 
-static int tb_port_set_link_width(struct tb_port *port, unsigned int width)
+/**
+ * tb_port_set_link_width() - Set target link width of the lane adapter
+ * @port: Lane adapter
+ * @width: Target link width (%1 or %2)
+ *
+ * Sets the target link width of the lane adapter to @width. Does not
+ * enable/disable lane bonding. For that call tb_port_set_lane_bonding().
+ *
+ * Return: %0 in case of success and negative errno in case of error
+ */
+int tb_port_set_link_width(struct tb_port *port, unsigned int width)
 {
 	u32 val;
 	int ret;
@@ -1026,12 +1036,58 @@ static int tb_port_set_link_width(struct tb_port *port, unsigned int width)
 		return -EINVAL;
 	}
 
-	val |= LANE_ADP_CS_1_LB;
-
 	return tb_port_write(port, &val, TB_CFG_PORT,
 			     port->cap_phy + LANE_ADP_CS_1, 1);
 }
 
+/**
+ * tb_port_set_lane_bonding() - Enable/disable lane bonding
+ * @port: Lane adapter
+ * @bonding: enable/disable bonding
+ *
+ * Enables or disables lane bonding. This should be called after target
+ * link width has been set (tb_port_set_link_width()). Note in most
+ * cases one should use tb_port_lane_bonding_enable() instead to enable
+ * lane bonding.
+ *
+ * As a side effect sets @port->bonding accordingly (and does the same
+ * for lane 1 too).
+ *
+ * Return: %0 in case of success and negative errno in case of error
+ */
+int tb_port_set_lane_bonding(struct tb_port *port, bool bonding)
+{
+	u32 val;
+	int ret;
+
+	if (!port->cap_phy)
+		return -EINVAL;
+
+	ret = tb_port_read(port, &val, TB_CFG_PORT,
+			   port->cap_phy + LANE_ADP_CS_1, 1);
+	if (ret)
+		return ret;
+
+	if (bonding)
+		val |= LANE_ADP_CS_1_LB;
+	else
+		val &= ~LANE_ADP_CS_1_LB;
+
+	ret = tb_port_write(port, &val, TB_CFG_PORT,
+			    port->cap_phy + LANE_ADP_CS_1, 1);
+	if (ret)
+		return ret;
+
+	/*
+	 * When lane 0 bonding is set it will affect lane 1 too so
+	 * update both.
+	 */
+	port->bonded = bonding;
+	port->dual_link_port->bonded = bonding;
+
+	return 0;
+}
+
 /**
  * tb_port_lane_bonding_enable() - Enable bonding on port
  * @port: port to enable
@@ -1056,22 +1112,27 @@ int tb_port_lane_bonding_enable(struct tb_port *port)
 	if (ret == 1) {
 		ret = tb_port_set_link_width(port, 2);
 		if (ret)
-			return ret;
+			goto err_lane0;
 	}
 
 	ret = tb_port_get_link_width(port->dual_link_port);
 	if (ret == 1) {
 		ret = tb_port_set_link_width(port->dual_link_port, 2);
-		if (ret) {
-			tb_port_set_link_width(port, 1);
-			return ret;
-		}
+		if (ret)
+			goto err_lane0;
 	}
 
-	port->bonded = true;
-	port->dual_link_port->bonded = true;
+	ret = tb_port_set_lane_bonding(port, true);
+	if (ret)
+		goto err_lane1;
 
 	return 0;
+
+err_lane1:
+	tb_port_set_link_width(port->dual_link_port, 1);
+err_lane0:
+	tb_port_set_link_width(port, 1);
+	return ret;
 }
 
 /**
@@ -1080,13 +1141,10 @@ int tb_port_lane_bonding_enable(struct tb_port *port)
  *
  * Disable bonding by setting the link width of the port and the
  * other port in case of dual link port.
- *
  */
 void tb_port_lane_bonding_disable(struct tb_port *port)
 {
-	port->dual_link_port->bonded = false;
-	port->bonded = false;
-
+	tb_port_set_lane_bonding(port, false);
 	tb_port_set_link_width(port->dual_link_port, 1);
 	tb_port_set_link_width(port, 1);
 }

drivers/thunderbolt/tb.h

@@ -1024,6 +1024,8 @@ static inline bool tb_port_use_credit_allocation(const struct tb_port *port)
 
 int tb_port_get_link_speed(struct tb_port *port);
 int tb_port_get_link_width(struct tb_port *port);
+int tb_port_set_link_width(struct tb_port *port, unsigned int width);
+int tb_port_set_lane_bonding(struct tb_port *port, bool bonding);
 int tb_port_lane_bonding_enable(struct tb_port *port);
 void tb_port_lane_bonding_disable(struct tb_port *port);
 int tb_port_wait_for_link_width(struct tb_port *port, int width,