[PATCH v2 1/7] usb: typec: Add driver for Thunderbolt 3 Alternate Mode

Abhishek Pandit-Subedi
2024-10-30T21:29:06Z

From: Heikki Krogerus <heikki.krogerus@linux.intel.com>

Thunderbolt 3 Alternate Mode entry flow is described in
USB Type-C Specification Release 2.0.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Co-developed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
---

Changes:
* Delay cable + plug checks so that the module doesn't fail to probe
if cable + plug information isn't available by the time the partner
altmode is registered.
* Remove unncessary brace after if (IS_ERR(plug))

The rest of this patch should be the same as Heikki's original RFC.

Changes in v2:
- Use <linux/usb/typec_tbt.h> and add missing TBT_CABLE_ROUNDED
- Pass struct typec_thunderbolt_data to typec_altmode_notify
- Rename TYPEC_TBT_MODE to USB_TYPEC_TBT_MODE
- Use USB_TYPEC_TBT_SID and USB_TYPEC_TBT_MODE for device id
- Change module license to GPL due to checkpatch warning

drivers/platform/chrome/cros_ec_typec.c | 2 +-
drivers/usb/typec/altmodes/Kconfig | 9 +
drivers/usb/typec/altmodes/Makefile | 2 +
drivers/usb/typec/altmodes/thunderbolt.c | 308 +++++++++++++++++++++++
include/linux/usb/typec_tbt.h | 3 +-
5 files changed, 322 insertions(+), 2 deletions(-)
create mode 100644 drivers/usb/typec/altmodes/thunderbolt.c

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index c7781aea0b88..53d93baa36a8 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -499,7 +499,7 @@ static int cros_typec_enable_tbt(struct cros_typec_data *typec,
}

port->state.data = &data;
- port->state.mode = TYPEC_TBT_MODE;
+ port->state.mode = USB_TYPEC_TBT_MODE;

return typec_mux_set(port->mux, &port->state);
}
diff --git a/drivers/usb/typec/altmodes/Kconfig b/drivers/usb/typec/altmodes/Kconfig
index 1a6b5e872b0d..7867fa7c405d 100644
--- a/drivers/usb/typec/altmodes/Kconfig
+++ b/drivers/usb/typec/altmodes/Kconfig
@@ -23,4 +23,13 @@ config TYPEC_NVIDIA_ALTMODE
To compile this driver as a module, choose M here: the
module will be called typec_nvidia.

+config TYPEC_TBT_ALTMODE
+ tristate "Thunderbolt3 Alternate Mode driver"
+ help
+ Select this option if you have Thunderbolt3 hardware on your
+ system.
+
+ To compile this driver as a module, choose M here: the
+ module will be called typec_thunderbolt.
+
endmenu
diff --git a/drivers/usb/typec/altmodes/Makefile b/drivers/usb/typec/altmodes/Makefile
index 45717548b396..508a68351bd2 100644
--- a/drivers/usb/typec/altmodes/Makefile
+++ b/drivers/usb/typec/altmodes/Makefile
@@ -4,3 +4,5 @@ obj-$(CONFIG_TYPEC_DP_ALTMODE) += typec_displayport.o
typec_displayport-y := displayport.o
obj-$(CONFIG_TYPEC_NVIDIA_ALTMODE) += typec_nvidia.o
typec_nvidia-y := nvidia.o
+obj-$(CONFIG_TYPEC_TBT_ALTMODE) += typec_thunderbolt.o
+typec_thunderbolt-y := thunderbolt.o
diff --git a/drivers/usb/typec/altmodes/thunderbolt.c b/drivers/usb/typec/altmodes/thunderbolt.c
new file mode 100644
index 000000000000..8380b22d26a7
--- /dev/null
+++ b/drivers/usb/typec/altmodes/thunderbolt.c
@@ -0,0 +1,308 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * USB Typec-C Thuderbolt3 Alternate Mode driver
+ *
+ * Copyright (C) 2019 Intel Corporation
+ * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/usb/pd_vdo.h>
+#include <linux/usb/typec_altmode.h>
+#include <linux/usb/typec_tbt.h>
+
+enum tbt_state {
+ TBT_STATE_IDLE,
+ TBT_STATE_SOP_P_ENTER,
+ TBT_STATE_SOP_PP_ENTER,
+ TBT_STATE_ENTER,
+ TBT_STATE_EXIT,
+ TBT_STATE_SOP_PP_EXIT,
+ TBT_STATE_SOP_P_EXIT
+};
+
+struct tbt_altmode {
+ enum tbt_state state;
+ struct typec_cable *cable;
+ struct typec_altmode *alt;
+ struct typec_altmode *plug[2];
+ u32 enter_vdo;
+
+ struct work_struct work;
+ struct mutex lock; /* device lock */
+};
+
+static bool tbt_ready(struct typec_altmode *alt);
+
+static int tbt_enter_mode(struct tbt_altmode *tbt)
+{
+ struct typec_altmode *plug = tbt->plug[TYPEC_PLUG_SOP_P];
+ u32 vdo;
+
+ vdo = tbt->alt->vdo & (TBT_VENDOR_SPECIFIC_B0 | TBT_VENDOR_SPECIFIC_B1);
+ vdo |= tbt->alt->vdo & TBT_INTEL_SPECIFIC_B0;
+ vdo |= TBT_MODE;
+
+ if (plug) {
+ if (typec_cable_is_active(tbt->cable))
+ vdo |= TBT_ENTER_MODE_ACTIVE_CABLE;
+
+ vdo |= TBT_ENTER_MODE_CABLE_SPEED(TBT_CABLE_SPEED(plug->vdo));
+ vdo |= plug->vdo & TBT_CABLE_ROUNDED;
+ vdo |= plug->vdo & TBT_CABLE_OPTICAL;
+ vdo |= plug->vdo & TBT_CABLE_RETIMER;
+ vdo |= plug->vdo & TBT_CABLE_LINK_TRAINING;
+ } else {
+ vdo |= TBT_ENTER_MODE_CABLE_SPEED(TBT_CABLE_USB3_PASSIVE);
+ }
+
+ tbt->enter_vdo = vdo;
+ return typec_altmode_enter(tbt->alt, &vdo);
+}
+
+static void tbt_altmode_work(struct work_struct *work)
+{
+ struct tbt_altmode *tbt = container_of(work, struct tbt_altmode, work);
+ int ret;
+
+ mutex_lock(&tbt->lock);
+
+ switch (tbt->state) {
+ case TBT_STATE_SOP_P_ENTER:
+ ret = typec_altmode_enter(tbt->plug[TYPEC_PLUG_SOP_P], NULL);
+ if (ret)
+ dev_dbg(&tbt->plug[TYPEC_PLUG_SOP_P]->dev,
+ "failed to enter mode (%d)\n", ret);
+ break;
+ case TBT_STATE_SOP_PP_ENTER:
+ ret = typec_altmode_enter(tbt->plug[TYPEC_PLUG_SOP_PP], NULL);
+ if (ret)
+ dev_dbg(&tbt->plug[TYPEC_PLUG_SOP_PP]->dev,
+ "failed to enter mode (%d)\n", ret);
+ break;
+ case TBT_STATE_ENTER:
+ ret = tbt_enter_mode(tbt);
+ if (ret)
+ dev_dbg(&tbt->alt->dev, "failed to enter mode (%d)\n",
+ ret);
+ break;
+ case TBT_STATE_EXIT:
+ typec_altmode_exit(tbt->alt);
+ break;
+ case TBT_STATE_SOP_PP_EXIT:
+ typec_altmode_exit(tbt->plug[TYPEC_PLUG_SOP_PP]);
+ break;
+ case TBT_STATE_SOP_P_EXIT:
+ typec_altmode_exit(tbt->plug[TYPEC_PLUG_SOP_P]);
+ break;
+ default:
+ break;
+ }
+
+ tbt->state = TBT_STATE_IDLE;
+
+ mutex_unlock(&tbt->lock);
+}
+
+static int tbt_altmode_vdm(struct typec_altmode *alt,
+ const u32 hdr, const u32 *vdo, int count)
+{
+ struct tbt_altmode *tbt = typec_altmode_get_drvdata(alt);
+ int cmd_type = PD_VDO_CMDT(hdr);
+ int cmd = PD_VDO_CMD(hdr);
+
+ mutex_lock(&tbt->lock);
+
+ if (tbt->state != TBT_STATE_IDLE) {
+ mutex_unlock(&tbt->lock);
+ return -EBUSY;
+ }
+
+ switch (cmd_type) {
+ case CMDT_RSP_ACK:
+ switch (cmd) {
+ case CMD_ENTER_MODE:
+ /*
+ * Following the order describeded in USB Type-C Spec
+ * R2.0 Section 6.7.3.
+ */
+ if (alt == tbt->plug[TYPEC_PLUG_SOP_P]) {
+ if (tbt->plug[TYPEC_PLUG_SOP_PP])
+ tbt->state = TBT_STATE_SOP_PP_ENTER;
+ else
+ tbt->state = TBT_STATE_ENTER;
+ } else if (alt == tbt->plug[TYPEC_PLUG_SOP_PP]) {
+ tbt->state = TBT_STATE_ENTER;
+ } else {
+ struct typec_thunderbolt_data data;
+
+ data.device_mode = tbt->alt->vdo;
+ data.cable_mode =
+ tbt->plug[TYPEC_PLUG_SOP_P] ?
+ tbt->plug[TYPEC_PLUG_SOP_P]
+ ->vdo :
+ 0;
+ data.enter_vdo = tbt->enter_vdo;
+
+ typec_altmode_notify(alt, TYPEC_STATE_MODAL, &data);
+ }
+ break;
+ case CMD_EXIT_MODE:
+ if (alt == tbt->alt) {
+ if (tbt->plug[TYPEC_PLUG_SOP_PP])
+ tbt->state = TBT_STATE_SOP_PP_EXIT;
+ else if (tbt->plug[TYPEC_PLUG_SOP_P])
+ tbt->state = TBT_STATE_SOP_P_EXIT;
+ } else if (alt == tbt->plug[TYPEC_PLUG_SOP_PP]) {
+ tbt->state = TBT_STATE_SOP_P_EXIT;
+ }
+ break;
+ }
+ break;
+ case CMDT_RSP_NAK:
+ switch (cmd) {
+ case CMD_ENTER_MODE:
+ dev_warn(&alt->dev, "Enter Mode refused\n");
+ break;
+ default:
+ break;
+ }
+ break;
+ default:
+ break;
+ }
+
+ if (tbt->state != TBT_STATE_IDLE)
+ schedule_work(&tbt->work);
+
+ mutex_unlock(&tbt->lock);
+
+ return 0;
+}
+
+static int tbt_altmode_activate(struct typec_altmode *alt, int activate)
+{
+ struct tbt_altmode *tbt = typec_altmode_get_drvdata(alt);
+ int ret;
+
+ mutex_lock(&tbt->lock);
+
+ if (!tbt_ready(alt))
+ return -ENODEV;
+
+ /* Preventing the user space from entering/exiting the cable alt mode */
+ if (alt != tbt->alt)
+ ret = -EPERM;
+ else if (activate)
+ ret = tbt_enter_mode(tbt);
+ else
+ ret = typec_altmode_exit(alt);
+
+ mutex_unlock(&tbt->lock);
+
+ return ret;
+}
+
+static const struct typec_altmode_ops tbt_altmode_ops = {
+ .vdm = tbt_altmode_vdm,
+ .activate = tbt_altmode_activate
+};
+
+static int tbt_altmode_probe(struct typec_altmode *alt)
+{
+ struct tbt_altmode *tbt;
+
+ tbt = devm_kzalloc(&alt->dev, sizeof(*tbt), GFP_KERNEL);
+ if (!tbt)
+ return -ENOMEM;
+
+ INIT_WORK(&tbt->work, tbt_altmode_work);
+ mutex_init(&tbt->lock);
+ tbt->alt = alt;
+
+ alt->desc = "Thunderbolt3";
+ typec_altmode_set_drvdata(alt, tbt);
+ typec_altmode_set_ops(alt, &tbt_altmode_ops);
+
+ if (tbt_ready(alt)) {
+ if (tbt->plug[TYPEC_PLUG_SOP_PP])
+ tbt->state = TBT_STATE_SOP_PP_ENTER;
+ else if (tbt->plug[TYPEC_PLUG_SOP_P])
+ tbt->state = TBT_STATE_SOP_P_ENTER;
+ else
+ tbt->state = TBT_STATE_ENTER;
+ schedule_work(&tbt->work);
+ }
+
+ return 0;
+}
+
+static void tbt_altmode_remove(struct typec_altmode *alt)
+{
+ struct tbt_altmode *tbt = typec_altmode_get_drvdata(alt);
+
+ for (int i = TYPEC_PLUG_SOP_PP; i > 0; --i) {
+ if (tbt->plug[i])
+ typec_altmode_put_plug(tbt->plug[i]);
+ }
+
+ if (tbt->cable)
+ typec_cable_put(tbt->cable);
+}
+
+static bool tbt_ready(struct typec_altmode *alt)
+{
+ struct tbt_altmode *tbt = typec_altmode_get_drvdata(alt);
+ struct typec_altmode *plug;
+
+ if (tbt->cable)
+ return true;
+
+ /* Thundebolt 3 requires a cable with eMarker */
+ tbt->cable = typec_cable_get(typec_altmode2port(tbt->alt));
+ if (!tbt->cable)
+ return false;
+
+ /* We accept systems without SOP' or SOP''. This means the port altmode
+ * driver will be responsible for properly ordering entry/exit.
+ */
+ for (int i = 0; i < TYPEC_PLUG_SOP_PP + 1; i++) {
+ plug = typec_altmode_get_plug(tbt->alt, i);
+ if (IS_ERR(plug))
+ continue;
+
+ if (!plug || plug->svid != USB_TYPEC_VENDOR_INTEL)
+ break;
+
+ plug->desc = "Thunderbolt3";
+ plug->ops = &tbt_altmode_ops;
+ typec_altmode_set_drvdata(plug, tbt);
+
+ tbt->plug[i] = plug;
+ }
+
+ return true;
+}
+
+static const struct typec_device_id tbt_typec_id[] = {
+ { USB_TYPEC_TBT_SID, USB_TYPEC_TBT_MODE },
+ { }
+};
+MODULE_DEVICE_TABLE(typec, tbt_typec_id);
+
+static struct typec_altmode_driver tbt_altmode_driver = {
+ .id_table = tbt_typec_id,
+ .probe = tbt_altmode_probe,
+ .remove = tbt_altmode_remove,
+ .driver = {
+ .name = "typec-thunderbolt",
+ .owner = THIS_MODULE,
+ }
+};
+module_typec_altmode_driver(tbt_altmode_driver);
+
+MODULE_AUTHOR("Heikki Krogerus <heikki.krogerus@linux.intel.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Thunderbolt3 USB Type-C Alternate Mode");
diff --git a/include/linux/usb/typec_tbt.h b/include/linux/usb/typec_tbt.h
index fa97d7e00f5c..3ff82641f6a0 100644
--- a/include/linux/usb/typec_tbt.h
+++ b/include/linux/usb/typec_tbt.h
@@ -10,7 +10,7 @@
#define USB_TYPEC_TBT_SID USB_TYPEC_VENDOR_INTEL

/* Connector state for Thunderbolt3 */
-#define TYPEC_TBT_MODE TYPEC_STATE_MODAL
+#define USB_TYPEC_TBT_MODE TYPEC_STATE_MODAL

/**
* struct typec_thunderbolt_data - Thundebolt3 Alt Mode specific data
@@ -44,6 +44,7 @@ struct typec_thunderbolt_data {

#define TBT_GEN3_NON_ROUNDED 0
#define TBT_GEN3_GEN4_ROUNDED_NON_ROUNDED 1
+#define TBT_CABLE_ROUNDED BIT(19)
#define TBT_CABLE_OPTICAL BIT(21)
#define TBT_CABLE_RETIMER BIT(22)
#define TBT_CABLE_LINK_TRAINING BIT(23)
--
2.47.0.163.g1226f6d8fa-goog