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Message-ID: <Z0DRWhZ745-N0DFE@google.com>
Date: Fri, 22 Nov 2024 18:50:54 +0000
From: Benson Leung <bleung@...gle.com>
To: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Cc: heikki.krogerus@...ux.intel.com, tzungbi@...nel.org,
linux-usb@...r.kernel.org, chrome-platform@...ts.linux.dev,
jthies@...gle.com, akuchynski@...gle.com, pmalani@...omium.org,
dmitry.baryshkov@...aro.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org, danielgeorgem@...gle.com
Subject: Re: [PATCH v3 2/7] usb: typec: Add driver for Thunderbolt 3
Alternate Mode
Hi Abhishek,
On Thu, Nov 07, 2024 at 11:29:55AM -0800, Abhishek Pandit-Subedi wrote:
> From: Heikki Krogerus <heikki.krogerus@...ux.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@...ux.intel.com>
> Co-developed-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.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 v3:
> - Revert rename of TYPEC_TBT_MODE
> - Remove mode from typec_device_id
>
> 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/usb/typec/altmodes/Kconfig | 9 +
> drivers/usb/typec/altmodes/Makefile | 2 +
> drivers/usb/typec/altmodes/thunderbolt.c | 308 +++++++++++++++++++++++
> include/linux/usb/typec_tbt.h | 1 +
> 4 files changed, 320 insertions(+)
> create mode 100644 drivers/usb/typec/altmodes/thunderbolt.c
>
> 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..a945b9d35a1d
> --- /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@...ux.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;
You need to mutex_unlock(&tbt->lock); before the return.
Credit to danielgeorgem@...gle.com for his catching this in his code review.
> +
> + /* 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 },
> + { }
> +};
> +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@...ux.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..55dcea12082c 100644
> --- a/include/linux/usb/typec_tbt.h
> +++ b/include/linux/usb/typec_tbt.h
> @@ -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)
> --
> 2.47.0.277.g8800431eea-goog
>
>
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