platform/chrome: cros_ec_typec: Add TBT compat support

Add mux control support for Thunderbolt compatibility mode.
Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Co-developed-by: Azhar Shaikh <azhar.shaikh@intel.com>
Co-developed-by: Casey Bowman <casey.g.bowman@intel.com>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

drivers/platform/chrome/cros_ec_typec.c

@@ -17,6 +17,7 @@
 #include <linux/usb/typec_altmode.h>
 #include <linux/usb/typec_dp.h>
 #include <linux/usb/typec_mux.h>
+#include <linux/usb/typec_tbt.h>
 #include <linux/usb/role.h>
 
 #define DRV_NAME "cros-ec-typec"
@@ -24,6 +25,7 @@
 /* Supported alt modes. */
 enum {
 	CROS_EC_ALTMODE_DP = 0,
+	CROS_EC_ALTMODE_TBT,
 	CROS_EC_ALTMODE_MAX,
 };
 
@@ -165,6 +167,14 @@ static void cros_typec_register_port_altmodes(struct cros_typec_data *typec,
 	port->p_altmode[CROS_EC_ALTMODE_DP].svid = USB_TYPEC_DP_SID;
 	port->p_altmode[CROS_EC_ALTMODE_DP].mode = USB_TYPEC_DP_MODE;
 
+	/*
+	 * Register TBT compatibility alt mode. The EC will not enter the mode
+	 * if it doesn't support it, so it's safe to register it unconditionally
+	 * here for now.
+	 */
+	port->p_altmode[CROS_EC_ALTMODE_TBT].svid = USB_TYPEC_TBT_SID;
+	port->p_altmode[CROS_EC_ALTMODE_TBT].mode = TYPEC_ANY_MODE;
+
 	port->state.alt = NULL;
 	port->state.mode = TYPEC_STATE_USB;
 	port->state.data = NULL;
@@ -391,6 +401,62 @@ static int cros_typec_usb_safe_state(struct cros_typec_port *port)
 	return typec_mux_set(port->mux, &port->state);
 }
 
+/*
+ * Spoof the VDOs that were likely communicated by the partner for TBT alt
+ * mode.
+ */
+static int cros_typec_enable_tbt(struct cros_typec_data *typec,
+				 int port_num,
+				 struct ec_response_usb_pd_control_v2 *pd_ctrl)
+{
+	struct cros_typec_port *port = typec->ports[port_num];
+	struct typec_thunderbolt_data data;
+	int ret;
+
+	if (typec->pd_ctrl_ver < 2) {
+		dev_err(typec->dev,
+			"PD_CTRL version too old: %d\n", typec->pd_ctrl_ver);
+		return -ENOTSUPP;
+	}
+
+	/* Device Discover Mode VDO */
+	data.device_mode = TBT_MODE;
+
+	if (pd_ctrl->control_flags & USB_PD_CTRL_TBT_LEGACY_ADAPTER)
+		data.device_mode = TBT_SET_ADAPTER(TBT_ADAPTER_TBT3);
+
+	/* Cable Discover Mode VDO */
+	data.cable_mode = TBT_MODE;
+	data.cable_mode |= TBT_SET_CABLE_SPEED(pd_ctrl->cable_speed);
+
+	if (pd_ctrl->control_flags & USB_PD_CTRL_OPTICAL_CABLE)
+		data.cable_mode |= TBT_CABLE_OPTICAL;
+
+	if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_LINK_UNIDIR)
+		data.cable_mode |= TBT_CABLE_LINK_TRAINING;
+
+	if (pd_ctrl->cable_gen)
+		data.cable_mode |= TBT_CABLE_ROUNDED;
+
+	/* Enter Mode VDO */
+	data.enter_vdo = TBT_SET_CABLE_SPEED(pd_ctrl->cable_speed);
+
+	if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_CABLE)
+		data.enter_vdo |= TBT_ENTER_MODE_ACTIVE_CABLE;
+
+	if (!port->state.alt) {
+		port->state.alt = &port->p_altmode[CROS_EC_ALTMODE_TBT];
+		ret = cros_typec_usb_safe_state(port);
+		if (ret)
+			return ret;
+	}
+
+	port->state.data = &data;
+	port->state.mode = TYPEC_TBT_MODE;
+
+	return typec_mux_set(port->mux, &port->state);
+}
+
 /* Spoof the VDOs that were likely communicated by the partner. */
 static int cros_typec_enable_dp(struct cros_typec_data *typec,
 				int port_num,
@@ -448,7 +514,9 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
 	if (ret)
 		return ret;
 
-	if (mux_flags & USB_PD_MUX_DP_ENABLED) {
+	if (mux_flags & USB_PD_MUX_TBT_COMPAT_ENABLED) {
+		ret = cros_typec_enable_tbt(typec, port_num, pd_ctrl);
+	} else if (mux_flags & USB_PD_MUX_DP_ENABLED) {
 		ret = cros_typec_enable_dp(typec, port_num, pd_ctrl);
 	} else if (mux_flags & USB_PD_MUX_SAFE_MODE) {
 		ret = cros_typec_usb_safe_state(port);