thunderbolt: Configure lanes when switch is initialized

Thunderbolt 2 devices and beyond need to have additional bits set in
link controller specific registers. This includes two bits in LC_SX_CTRL
that tell the link controller which lane is connected and whether it is
upstream facing or not.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/lc.c

@@ -19,3 +19,117 @@ int tb_lc_read_uuid(struct tb_switch *sw, u32 *uuid)
 		return -EINVAL;
 	return tb_sw_read(sw, uuid, TB_CFG_SWITCH, sw->cap_lc + TB_LC_FUSE, 4);
 }
+
+static int read_lc_desc(struct tb_switch *sw, u32 *desc)
+{
+	if (!sw->cap_lc)
+		return -EINVAL;
+	return tb_sw_read(sw, desc, TB_CFG_SWITCH, sw->cap_lc + TB_LC_DESC, 1);
+}
+
+static int find_port_lc_cap(struct tb_port *port)
+{
+	struct tb_switch *sw = port->sw;
+	int start, phys, ret, size;
+	u32 desc;
+
+	ret = read_lc_desc(sw, &desc);
+	if (ret)
+		return ret;
+
+	/* Start of port LC registers */
+	start = (desc & TB_LC_DESC_SIZE_MASK) >> TB_LC_DESC_SIZE_SHIFT;
+	size = (desc & TB_LC_DESC_PORT_SIZE_MASK) >> TB_LC_DESC_PORT_SIZE_SHIFT;
+	phys = tb_phy_port_from_link(port->port);
+
+	return sw->cap_lc + start + phys * size;
+}
+
+static int tb_lc_configure_lane(struct tb_port *port, bool configure)
+{
+	bool upstream = tb_is_upstream_port(port);
+	struct tb_switch *sw = port->sw;
+	u32 ctrl, lane;
+	int cap, ret;
+
+	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;
+
+	/* Resolve correct lane */
+	if (port->port % 2)
+		lane = TB_LC_SX_CTRL_L1C;
+	else
+		lane = TB_LC_SX_CTRL_L2C;
+
+	if (configure) {
+		ctrl |= lane;
+		if (upstream)
+			ctrl |= TB_LC_SX_CTRL_UPSTREAM;
+	} else {
+		ctrl &= ~lane;
+		if (upstream)
+			ctrl &= ~TB_LC_SX_CTRL_UPSTREAM;
+	}
+
+	return tb_sw_write(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+}
+
+/**
+ * tb_lc_configure_link() - Let LC know about configured link
+ * @sw: Switch that is being added
+ *
+ * Informs LC of both parent switch and @sw that there is established
+ * link between the two.
+ */
+int tb_lc_configure_link(struct tb_switch *sw)
+{
+	struct tb_port *up, *down;
+	int ret;
+
+	if (!sw->config.enabled || !tb_route(sw))
+		return 0;
+
+	up = tb_upstream_port(sw);
+	down = tb_port_at(tb_route(sw), tb_to_switch(sw->dev.parent));
+
+	/* Configure parent link toward this switch */
+	ret = tb_lc_configure_lane(down, true);
+	if (ret)
+		return ret;
+
+	/* Configure upstream link from this switch to the parent */
+	ret = tb_lc_configure_lane(up, true);
+	if (ret)
+		tb_lc_configure_lane(down, false);
+
+	return ret;
+}
+
+/**
+ * tb_lc_unconfigure_link() - Let LC know about unconfigured link
+ * @sw: Switch to unconfigure
+ *
+ * Informs LC of both parent switch and @sw that the link between the
+ * two does not exist anymore.
+ */
+void tb_lc_unconfigure_link(struct tb_switch *sw)
+{
+	struct tb_port *up, *down;
+
+	if (sw->is_unplugged || !sw->config.enabled || !tb_route(sw))
+		return;
+
+	up = tb_upstream_port(sw);
+	down = tb_port_at(tb_route(sw), tb_to_switch(sw->dev.parent));
+
+	tb_lc_configure_lane(up, false);
+	tb_lc_configure_lane(down, false);
+}

drivers/thunderbolt/switch.c

@@ -1276,6 +1276,10 @@ int tb_switch_configure(struct tb_switch *sw)
 	if (ret)
 		return ret;
 
+	ret = tb_lc_configure_link(sw);
+	if (ret)
+		return ret;
+
 	return tb_plug_events_active(sw, true);
 }
 
@@ -1486,6 +1490,7 @@ void tb_switch_remove(struct tb_switch *sw)
 
 	if (!sw->is_unplugged)
 		tb_plug_events_active(sw, false);
+	tb_lc_unconfigure_link(sw);
 
 	tb_switch_nvm_remove(sw);
 
@@ -1545,6 +1550,10 @@ int tb_switch_resume(struct tb_switch *sw)
 	if (err)
 		return err;
 
+	err = tb_lc_configure_link(sw);
+	if (err)
+		return err;
+
 	err = tb_plug_events_active(sw, true);
 	if (err)
 		return err;

drivers/thunderbolt/tb.h

@@ -465,6 +465,8 @@ int tb_drom_read(struct tb_switch *sw);
 int tb_drom_read_uid_only(struct tb_switch *sw, u64 *uid);
 
 int tb_lc_read_uuid(struct tb_switch *sw, u32 *uuid);
+int tb_lc_configure_link(struct tb_switch *sw);
+void tb_lc_unconfigure_link(struct tb_switch *sw);
 
 static inline int tb_route_length(u64 route)
 {

drivers/thunderbolt/tb_regs.h

@@ -238,6 +238,17 @@ struct tb_regs_hop {
 } __packed;
 
 /* Common link controller registers */
+#define TB_LC_DESC			0x02
+#define TB_LC_DESC_SIZE_SHIFT		8
+#define TB_LC_DESC_SIZE_MASK		GENMASK(15, 8)
+#define TB_LC_DESC_PORT_SIZE_SHIFT	16
+#define TB_LC_DESC_PORT_SIZE_MASK	GENMASK(27, 16)
 #define TB_LC_FUSE			0x03
 
+/* Link controller registers */
+#define TB_LC_SX_CTRL			0x96
+#define TB_LC_SX_CTRL_L1C		BIT(16)
+#define TB_LC_SX_CTRL_L2C		BIT(20)
+#define TB_LC_SX_CTRL_UPSTREAM		BIT(30)
+
 #endif