usb: typec: ucsi: Add Thunderbolt alternate mode support

Introduce support for Thunderbolt (TBT) alternate mode to the UCSI driver.
This allows the driver to manage the entry and exit of TBT altmode by
providing the necessary typec_altmode_ops.

ucsi_altmode_update_active() is invoked when the Connector Partner Changed
bit is set in the GET_CONNECTOR_STATUS data. This ensures that the
alternate mode's active state is synchronized with the current mode the
connector is operating in.

Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://patch.msgid.link/20260206115754.828954-1-akuchynski@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/ucsi/Makefile

@@ -17,6 +17,10 @@ ifneq ($(CONFIG_TYPEC_DP_ALTMODE),)
 	typec_ucsi-y			+= displayport.o
 endif
 
+ifneq ($(CONFIG_TYPEC_TBT_ALTMODE),)
+	typec_ucsi-y			+= thunderbolt.o
+endif
+
 obj-$(CONFIG_UCSI_ACPI)			+= ucsi_acpi.o
 obj-$(CONFIG_UCSI_CCG)			+= ucsi_ccg.o
 obj-$(CONFIG_UCSI_STM32G0)		+= ucsi_stm32g0.o

drivers/usb/typec/ucsi/thunderbolt.c

@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UCSI Thunderbolt Alternate Mode Support
+ *
+ * Copyright 2026 Google LLC
+ */
+
+#include <linux/usb/typec_tbt.h>
+#include <linux/usb/pd_vdo.h>
+#include <linux/err.h>
+#include <linux/dev_printk.h>
+#include <linux/device/devres.h>
+#include <linux/gfp_types.h>
+#include <linux/types.h>
+#include <linux/usb/typec_altmode.h>
+#include <linux/workqueue.h>
+
+#include "ucsi.h"
+
+/**
+ * struct ucsi_tbt - Thunderbolt Alternate Mode private data structure
+ * @con: Pointer to UCSI connector structure
+ * @alt: Pointer to typec altmode structure
+ * @work: Work structure
+ * @cam: An offset into the list of alternate modes supported by the PPM
+ * @header: VDO header
+ */
+struct ucsi_tbt {
+	struct ucsi_connector *con;
+	struct typec_altmode *alt;
+	struct work_struct work;
+	int cam;
+	u32 header;
+};
+
+static void ucsi_thunderbolt_work(struct work_struct *work)
+{
+	struct ucsi_tbt *tbt = container_of(work, struct ucsi_tbt, work);
+
+	if (typec_altmode_vdm(tbt->alt, tbt->header, NULL, 0))
+		dev_err(&tbt->alt->dev, "VDM 0x%x failed\n", tbt->header);
+
+	tbt->header = 0;
+}
+
+static int ucsi_thunderbolt_set_altmode(struct ucsi_tbt *tbt,
+					bool enter, u32 vdo)
+{
+	int svdm_version;
+	int cmd;
+	int ret;
+	u64 command = UCSI_SET_NEW_CAM |
+		      UCSI_CONNECTOR_NUMBER(tbt->con->num) |
+		      UCSI_SET_NEW_CAM_SET_AM(tbt->cam) |
+		      ((u64)vdo << 32);
+
+	if (enter)
+		command |= (1 << 23);
+
+	ret = ucsi_send_command(tbt->con->ucsi, command, NULL, 0);
+	if (ret < 0)
+		return ret;
+
+	svdm_version = typec_altmode_get_svdm_version(tbt->alt);
+	if (svdm_version < 0)
+		return svdm_version;
+
+	if (enter)
+		cmd = CMD_ENTER_MODE;
+	else
+		cmd = CMD_EXIT_MODE;
+	tbt->header = VDO(USB_TYPEC_TBT_SID, 1, svdm_version, cmd);
+	tbt->header |= VDO_OPOS(TYPEC_TBT_MODE);
+	tbt->header |= VDO_CMDT(CMDT_RSP_ACK);
+
+	schedule_work(&tbt->work);
+
+	return 0;
+}
+
+static int ucsi_thunderbolt_enter(struct typec_altmode *alt, u32 *vdo)
+{
+	struct ucsi_tbt *tbt = typec_altmode_get_drvdata(alt);
+	struct ucsi_connector *con = tbt->con;
+	u64 command;
+	u8 cur = 0;
+	int ret;
+
+	if (!ucsi_con_mutex_lock(con))
+		return -ENOTCONN;
+
+	command = UCSI_GET_CURRENT_CAM | UCSI_CONNECTOR_NUMBER(con->num);
+	ret = ucsi_send_command(con->ucsi, command, &cur, sizeof(cur));
+	if (ret < 0) {
+		if (con->ucsi->version > 0x0100)
+			goto err_unlock;
+		cur = 0xff;
+	}
+
+	if (cur != 0xff) {
+		if (cur >= UCSI_MAX_ALTMODES || con->port_altmode[cur] != alt)
+			ret = -EBUSY;
+		else
+			ret = 0;
+		goto err_unlock;
+	}
+
+	ret = ucsi_thunderbolt_set_altmode(tbt, true, *vdo);
+	ucsi_altmode_update_active(tbt->con);
+
+err_unlock:
+	ucsi_con_mutex_unlock(con);
+
+	return ret;
+}
+
+static int ucsi_thunderbolt_exit(struct typec_altmode *alt)
+{
+	struct ucsi_tbt *tbt = typec_altmode_get_drvdata(alt);
+	int ret;
+
+	if (!ucsi_con_mutex_lock(tbt->con))
+		return -ENOTCONN;
+
+	ret = ucsi_thunderbolt_set_altmode(tbt, false, 0);
+
+	ucsi_con_mutex_unlock(tbt->con);
+
+	return ret;
+}
+
+static int ucsi_thunderbolt_vdm(struct typec_altmode *alt,
+				u32 header, const u32 *data, int count)
+{
+	struct ucsi_tbt *tbt = typec_altmode_get_drvdata(alt);
+	int cmd_type = PD_VDO_CMDT(header);
+	int cmd = PD_VDO_CMD(header);
+	int svdm_version;
+
+	if (!ucsi_con_mutex_lock(tbt->con))
+		return -ENOTCONN;
+
+	svdm_version = typec_altmode_get_svdm_version(alt);
+	if (svdm_version < 0) {
+		ucsi_con_mutex_unlock(tbt->con);
+		return svdm_version;
+	}
+
+	switch (cmd_type) {
+	case CMDT_INIT:
+		if (PD_VDO_SVDM_VER(header) < svdm_version) {
+			svdm_version = PD_VDO_SVDM_VER(header);
+			typec_partner_set_svdm_version(tbt->con->partner, svdm_version);
+		}
+		tbt->header = VDO(USB_TYPEC_TBT_SID, 1, svdm_version, cmd);
+		tbt->header |= VDO_OPOS(TYPEC_TBT_MODE);
+		tbt->header |= VDO_CMDT(CMDT_RSP_ACK);
+
+		schedule_work(&tbt->work);
+		break;
+	default:
+		break;
+	}
+
+	ucsi_con_mutex_unlock(tbt->con);
+
+	return 0;
+}
+
+static const struct typec_altmode_ops ucsi_thunderbolt_ops = {
+	.enter = ucsi_thunderbolt_enter,
+	.exit = ucsi_thunderbolt_exit,
+	.vdm = ucsi_thunderbolt_vdm,
+};
+
+struct typec_altmode *ucsi_register_thunderbolt(struct ucsi_connector *con,
+						bool override, int offset,
+						struct typec_altmode_desc *desc)
+{
+	struct typec_altmode *alt;
+	struct ucsi_tbt *tbt;
+
+	alt = typec_port_register_altmode(con->port, desc);
+	if (IS_ERR(alt) || !override)
+		return alt;
+
+	tbt = devm_kzalloc(&alt->dev, sizeof(*tbt), GFP_KERNEL);
+	if (!tbt) {
+		typec_unregister_altmode(alt);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	tbt->cam = offset;
+	tbt->con = con;
+	tbt->alt = alt;
+	INIT_WORK(&tbt->work, ucsi_thunderbolt_work);
+	typec_altmode_set_drvdata(alt, tbt);
+	typec_altmode_set_ops(alt, &ucsi_thunderbolt_ops);
+
+	return alt;
+}
+
+void ucsi_thunderbolt_remove_partner(struct typec_altmode *alt)
+{
+	struct ucsi_tbt *tbt;
+
+	if (alt) {
+		tbt = typec_altmode_get_drvdata(alt);
+		if (tbt)
+			cancel_work_sync(&tbt->work);
+	}
+}

drivers/usb/typec/ucsi/ucsi.c

@@ -13,6 +13,7 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/usb/typec_dp.h>
+#include <linux/usb/typec_tbt.h>
 
 #include "ucsi.h"
 #include "trace.h"
@@ -417,6 +418,9 @@ static int ucsi_register_altmode(struct ucsi_connector *con,
 				alt = ucsi_register_displayport(con, override,
 								i, desc);
 			break;
+		case USB_TYPEC_TBT_SID:
+			alt = ucsi_register_thunderbolt(con, override, i, desc);
+			break;
 		default:
 			alt = typec_port_register_altmode(con->port, desc);
 			break;
@@ -647,12 +651,15 @@ static void ucsi_unregister_altmodes(struct ucsi_connector *con, u8 recipient)
 	}
 
 	while (adev[i]) {
-		if (recipient == UCSI_RECIPIENT_SOP &&
-		    (adev[i]->svid == USB_TYPEC_DP_SID ||
-			(adev[i]->svid == USB_TYPEC_NVIDIA_VLINK_SID &&
-			adev[i]->vdo != USB_TYPEC_NVIDIA_VLINK_DBG_VDO))) {
+		if (recipient == UCSI_RECIPIENT_SOP) {
 			pdev = typec_altmode_get_partner(adev[i]);
-			ucsi_displayport_remove_partner((void *)pdev);
+
+			if (adev[i]->svid == USB_TYPEC_DP_SID ||
+			    (adev[i]->svid == USB_TYPEC_NVIDIA_VLINK_SID &&
+			     adev[i]->vdo != USB_TYPEC_NVIDIA_VLINK_DBG_VDO))
+				ucsi_displayport_remove_partner((void *)pdev);
+			else if (adev[i]->svid == USB_TYPEC_TBT_SID)
+				ucsi_thunderbolt_remove_partner((void *)pdev);
 		}
 		typec_unregister_altmode(adev[i]);
 		adev[i++] = NULL;
@@ -1318,6 +1325,7 @@ static void ucsi_handle_connector_change(struct work_struct *work)
 
 	if (con->partner && (change & UCSI_CONSTAT_PARTNER_CHANGE)) {
 		ucsi_partner_change(con);
+		ucsi_altmode_update_active(con);
 
 		/* Complete pending data role swap */
 		if (!completion_done(&con->complete))

drivers/usb/typec/ucsi/ucsi.h

@@ -600,6 +600,26 @@ static inline void
 ucsi_displayport_remove_partner(struct typec_altmode *adev) { }
 #endif /* CONFIG_TYPEC_DP_ALTMODE */
 
+#if IS_ENABLED(CONFIG_TYPEC_TBT_ALTMODE)
+struct typec_altmode *
+ucsi_register_thunderbolt(struct ucsi_connector *con,
+			  bool override, int offset,
+			  struct typec_altmode_desc *desc);
+
+void ucsi_thunderbolt_remove_partner(struct typec_altmode *adev);
+#else
+static inline struct typec_altmode *
+ucsi_register_thunderbolt(struct ucsi_connector *con,
+			  bool override, int offset,
+			  struct typec_altmode_desc *desc)
+{
+	return typec_port_register_altmode(con->port, desc);
+}
+
+static inline void
+ucsi_thunderbolt_remove_partner(struct typec_altmode *adev) { }
+#endif /* CONFIG_TYPEC_TBT_ALTMODE */
+
 #ifdef CONFIG_DEBUG_FS
 void ucsi_debugfs_init(void);
 void ucsi_debugfs_exit(void);