thunderbolt: Add support for lane bonding

Lane bonding allows aggregating two 10/20 Gb/s (depending on the
generation) lanes into a single 20/40 Gb/s bonded link. This allows
sharing the full bandwidth more efficiently. In order to establish lane
bonding we need to check that lane bonding is possible through link
controller and that both ends of the link actually supports 2x widths.
This also means that all the paths should be established through the
primary port so update tb_path_alloc() to handle this as well.

Lane bonding is supported starting from Falcon Ridge (2nd generation)
controllers.

We also expose the current speed and number of lanes under each device
except the host router following similar attribute naming than USB bus.
Expose speed and number of lanes for both directions to allow possibility
of asymmetric link in the future.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 288 insertions, 0 deletions

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 849681500daa..12a63f86820e 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -775,6 +775,132 @@ struct tb_port *tb_next_port_on_path(struct tb_port *start, struct tb_port *end,
 	return next;
 }
 
+static int tb_port_get_link_speed(struct tb_port *port)
+{
+	u32 val, speed;
+	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;
+
+	speed = (val & LANE_ADP_CS_1_CURRENT_SPEED_MASK) >>
+		LANE_ADP_CS_1_CURRENT_SPEED_SHIFT;
+	return speed == LANE_ADP_CS_1_CURRENT_SPEED_GEN3 ? 20 : 10;
+}
+
+static int tb_port_get_link_width(struct tb_port *port)
+{
+	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;
+
+	return (val & LANE_ADP_CS_1_CURRENT_WIDTH_MASK) >>
+		LANE_ADP_CS_1_CURRENT_WIDTH_SHIFT;
+}
+
+static bool tb_port_is_width_supported(struct tb_port *port, int width)
+{
+	u32 phy, widths;
+	int ret;
+
+	if (!port->cap_phy)
+		return false;
+
+	ret = tb_port_read(port, &phy, TB_CFG_PORT,
+			   port->cap_phy + LANE_ADP_CS_0, 1);
+	if (ret)
+		return ret;
+
+	widths = (phy & LANE_ADP_CS_0_SUPPORTED_WIDTH_MASK) >>
+		LANE_ADP_CS_0_SUPPORTED_WIDTH_SHIFT;
+
+	return !!(widths & width);
+}
+
+static int tb_port_set_link_width(struct tb_port *port, unsigned int width)
+{
+	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;
+
+	val &= ~LANE_ADP_CS_1_TARGET_WIDTH_MASK;
+	switch (width) {
+	case 1:
+		val |= LANE_ADP_CS_1_TARGET_WIDTH_SINGLE <<
+			LANE_ADP_CS_1_TARGET_WIDTH_SHIFT;
+		break;
+	case 2:
+		val |= LANE_ADP_CS_1_TARGET_WIDTH_DUAL <<
+			LANE_ADP_CS_1_TARGET_WIDTH_SHIFT;
+		break;
+	default:
+		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);
+}
+
+static int tb_port_lane_bonding_enable(struct tb_port *port)
+{
+	int ret;
+
+	/*
+	 * Enable lane bonding for both links if not already enabled by
+	 * for example the boot firmware.
+	 */
+	ret = tb_port_get_link_width(port);
+	if (ret == 1) {
+		ret = tb_port_set_link_width(port, 2);
+		if (ret)
+			return ret;
+	}
+
+	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;
+		}
+	}
+
+	port->bonded = true;
+	port->dual_link_port->bonded = true;
+
+	return 0;
+}
+
+static void tb_port_lane_bonding_disable(struct tb_port *port)
+{
+	port->dual_link_port->bonded = false;
+	port->bonded = false;
+
+	tb_port_set_link_width(port->dual_link_port, 1);
+	tb_port_set_link_width(port, 1);
+}
+
 /**
  * tb_port_is_enabled() - Is the adapter port enabled
  * @port: Port to check
@@ -1183,6 +1309,36 @@ static ssize_t key_store(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR(key, 0600, key_show, key_store);
 
+static ssize_t speed_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	struct tb_switch *sw = tb_to_switch(dev);
+
+	return sprintf(buf, "%u.0 Gb/s\n", sw->link_speed);
+}
+
+/*
+ * Currently all lanes must run at the same speed but we expose here
+ * both directions to allow possible asymmetric links in the future.
+ */
+static DEVICE_ATTR(rx_speed, 0444, speed_show, NULL);
+static DEVICE_ATTR(tx_speed, 0444, speed_show, NULL);
+
+static ssize_t lanes_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	struct tb_switch *sw = tb_to_switch(dev);
+
+	return sprintf(buf, "%u\n", sw->link_width);
+}
+
+/*
+ * Currently link has same amount of lanes both directions (1 or 2) but
+ * expose them separately to allow possible asymmetric links in the future.
+ */
+static DEVICE_ATTR(rx_lanes, 0444, lanes_show, NULL);
+static DEVICE_ATTR(tx_lanes, 0444, lanes_show, NULL);
+
 static void nvm_authenticate_start(struct tb_switch *sw)
 {
 	struct pci_dev *root_port;
@@ -1340,6 +1496,10 @@ static struct attribute *switch_attrs[] = {
 	&dev_attr_key.attr,
 	&dev_attr_nvm_authenticate.attr,
 	&dev_attr_nvm_version.attr,
+	&dev_attr_rx_speed.attr,
+	&dev_attr_rx_lanes.attr,
+	&dev_attr_tx_speed.attr,
+	&dev_attr_tx_lanes.attr,
 	&dev_attr_vendor.attr,
 	&dev_attr_vendor_name.attr,
 	&dev_attr_unique_id.attr,
@@ -1370,6 +1530,13 @@ static umode_t switch_attr_is_visible(struct kobject *kobj,
 		    sw->security_level == TB_SECURITY_SECURE)
 			return attr->mode;
 		return 0;
+	} else if (attr == &dev_attr_rx_speed.attr ||
+		   attr == &dev_attr_rx_lanes.attr ||
+		   attr == &dev_attr_tx_speed.attr ||
+		   attr == &dev_attr_tx_lanes.attr) {
+		if (tb_route(sw))
+			return attr->mode;
+		return 0;
 	} else if (attr == &dev_attr_nvm_authenticate.attr) {
 		if (sw->dma_port && !sw->no_nvm_upgrade)
 			return attr->mode;
@@ -1769,6 +1936,123 @@ static int tb_switch_add_dma_port(struct tb_switch *sw)
 	return -ESHUTDOWN;
 }
 
+static bool tb_switch_lane_bonding_possible(struct tb_switch *sw)
+{
+	const struct tb_port *up = tb_upstream_port(sw);
+
+	if (!up->dual_link_port || !up->dual_link_port->remote)
+		return false;
+
+	return tb_lc_lane_bonding_possible(sw);
+}
+
+static int tb_switch_update_link_attributes(struct tb_switch *sw)
+{
+	struct tb_port *up;
+	bool change = false;
+	int ret;
+
+	if (!tb_route(sw) || tb_switch_is_icm(sw))
+		return 0;
+
+	up = tb_upstream_port(sw);
+
+	ret = tb_port_get_link_speed(up);
+	if (ret < 0)
+		return ret;
+	if (sw->link_speed != ret)
+		change = true;
+	sw->link_speed = ret;
+
+	ret = tb_port_get_link_width(up);
+	if (ret < 0)
+		return ret;
+	if (sw->link_width != ret)
+		change = true;
+	sw->link_width = ret;
+
+	/* Notify userspace that there is possible link attribute change */
+	if (device_is_registered(&sw->dev) && change)
+		kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
+
+	return 0;
+}
+
+/**
+ * tb_switch_lane_bonding_enable() - Enable lane bonding
+ * @sw: Switch to enable lane bonding
+ *
+ * Connection manager can call this function to enable lane bonding of a
+ * switch. If conditions are correct and both switches support the feature,
+ * lanes are bonded. It is safe to call this to any switch.
+ */
+int tb_switch_lane_bonding_enable(struct tb_switch *sw)
+{
+	struct tb_switch *parent = tb_to_switch(sw->dev.parent);
+	struct tb_port *up, *down;
+	u64 route = tb_route(sw);
+	int ret;
+
+	if (!route)
+		return 0;
+
+	if (!tb_switch_lane_bonding_possible(sw))
+		return 0;
+
+	up = tb_upstream_port(sw);
+	down = tb_port_at(route, parent);
+
+	if (!tb_port_is_width_supported(up, 2) ||
+	    !tb_port_is_width_supported(down, 2))
+		return 0;
+
+	ret = tb_port_lane_bonding_enable(up);
+	if (ret) {
+		tb_port_warn(up, "failed to enable lane bonding\n");
+		return ret;
+	}
+
+	ret = tb_port_lane_bonding_enable(down);
+	if (ret) {
+		tb_port_warn(down, "failed to enable lane bonding\n");
+		tb_port_lane_bonding_disable(up);
+		return ret;
+	}
+
+	tb_switch_update_link_attributes(sw);
+
+	tb_sw_dbg(sw, "lane bonding enabled\n");
+	return ret;
+}
+
+/**
+ * tb_switch_lane_bonding_disable() - Disable lane bonding
+ * @sw: Switch whose lane bonding to disable
+ *
+ * Disables lane bonding between @sw and parent. This can be called even
+ * if lanes were not bonded originally.
+ */
+void tb_switch_lane_bonding_disable(struct tb_switch *sw)
+{
+	struct tb_switch *parent = tb_to_switch(sw->dev.parent);
+	struct tb_port *up, *down;
+
+	if (!tb_route(sw))
+		return;
+
+	up = tb_upstream_port(sw);
+	if (!up->bonded)
+		return;
+
+	down = tb_port_at(tb_route(sw), parent);
+
+	tb_port_lane_bonding_disable(up);
+	tb_port_lane_bonding_disable(down);
+
+	tb_switch_update_link_attributes(sw);
+	tb_sw_dbg(sw, "lane bonding disabled\n");
+}
+
 /**
  * tb_switch_add() - Add a switch to the domain
  * @sw: Switch to add
@@ -1824,6 +2108,10 @@ int tb_switch_add(struct tb_switch *sw)
 				return ret;
 			}
 		}
+
+		ret = tb_switch_update_link_attributes(sw);
+		if (ret)
+			return ret;
 	}
 
 	ret = device_add(&sw->dev);