thunderbolt: Start lane initialization after sleep

USB4 spec says that for TBT3 compatible device routers the connection
manager needs to set SLI (Start Lane Initialization) to get the lanes
that were not connected back to functional state after sleep. Same needs
to be done if the link was XDomain.

Signed-off-by: Mika Westerberg <[e-mail]>
Acked-by: Yehezkel Bernat <[e-mail]>

drivers/thunderbolt/lc.c

···
 	tb_lc_set_xdomain_configured(port, false);
 }
 
+/**
+ * tb_lc_start_lane_initialization() - Start lane initialization
+ * @port: Device router lane 0 adapter
+ *
+ * Starts lane initialization for @port after the router resumed from
+ * sleep. Should be called for those downstream lane adapters that were
+ * not connected (tb_lc_configure_port() was not called) before sleep.
+ *
+ * Returns %0 in success and negative errno in case of failure.
+ */
+int tb_lc_start_lane_initialization(struct tb_port *port)
+{
+	struct tb_switch *sw = port->sw;
+	int ret, cap;
+	u32 ctrl;
+
+	if (!tb_route(sw))
+		return 0;
+
+	if (sw->generation < 2)
+		return 0;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return cap;
+
+	ret = tb_sw_read(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+	if (ret)
+		return ret;
+
+	ctrl |= TB_LC_SX_CTRL_SLI;
+
+	return tb_sw_write(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+}
+
 static int tb_lc_set_wake_one(struct tb_switch *sw, unsigned int offset,
 			      unsigned int flags)
 {

drivers/thunderbolt/switch.c

···
 	tb_port_set_link_width(port, 1);
 }
 
+static int tb_port_start_lane_initialization(struct tb_port *port)
+{
+	int ret;
+
+	if (tb_switch_is_usb4(port->sw))
+		return 0;
+
+	ret = tb_lc_start_lane_initialization(port);
+	return ret == -EINVAL ? 0 : ret;
+}
+
 /**
  * tb_port_is_enabled() - Is the adapter port enabled
  * @port: Port to check
···
 
 	/* check for surviving downstream switches */
 	tb_switch_for_each_port(sw, port) {
-		if (!tb_port_has_remote(port) && !port->xdomain)
+		if (!tb_port_has_remote(port) && !port->xdomain) {
+			/*
+			 * For disconnected downstream lane adapters
+			 * start lane initialization now so we detect
+			 * future connects.
+			 */
+			if (!tb_is_upstream_port(port) && tb_port_is_null(port))
+				tb_port_start_lane_initialization(port);
 			continue;
+		} else if (port->xdomain) {
+			/*
+			 * Start lane initialization for XDomain so the
+			 * link gets re-established.
+			 */
+			tb_port_start_lane_initialization(port);
+		}
 
 		if (tb_wait_for_port(port, true) <= 0) {
 			tb_port_warn(port,

drivers/thunderbolt/tb.h

···
 void tb_lc_unconfigure_port(struct tb_port *port);
 int tb_lc_configure_xdomain(struct tb_port *port);
 void tb_lc_unconfigure_xdomain(struct tb_port *port);
+int tb_lc_start_lane_initialization(struct tb_port *port);
 int tb_lc_set_wake(struct tb_switch *sw, unsigned int flags);
 int tb_lc_set_sleep(struct tb_switch *sw);
 bool tb_lc_lane_bonding_possible(struct tb_switch *sw);

drivers/thunderbolt/tb_regs.h

···
 #define TB_LC_SX_CTRL_L1D		BIT(17)
 #define TB_LC_SX_CTRL_L2C		BIT(20)
 #define TB_LC_SX_CTRL_L2D		BIT(21)
+#define TB_LC_SX_CTRL_SLI		BIT(29)
 #define TB_LC_SX_CTRL_UPSTREAM		BIT(30)
 #define TB_LC_SX_CTRL_SLP		BIT(31)