usb: typec: Add driver for NVIDIA Alt Modes

Latest NVIDIA GPUs support VirtualLink device. Since USBIF
has not assigned a Standard ID (SID) for VirtualLink
so using NVIDA VID 0x955 as SVID.
Signed-off-by: Ajay Gupta <ajayg@nvidia.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/altmodes/Kconfig

@@ -12,4 +12,14 @@ config TYPEC_DP_ALTMODE
 	  To compile this driver as a module, choose M here: the
 	  module will be called typec_displayport.
 
+config TYPEC_NVIDIA_ALTMODE
+	tristate "NVIDIA Alternate Mode driver"
+	depends on TYPEC_DP_ALTMODE
+	help
+	  Latest NVIDIA GPUs support VirtualLink devices. Select this
+	  to enable support for VirtualLink devices with NVIDIA GPUs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called typec_displayport.
+
 endmenu

drivers/usb/typec/altmodes/Makefile

@@ -2,3 +2,5 @@
 
 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

drivers/usb/typec/altmodes/nvidia.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 NVIDIA Corporation. All rights reserved.
+ *
+ * NVIDIA USB Type-C Alt Mode Driver
+ */
+#include <linux/module.h>
+#include <linux/usb/typec_altmode.h>
+#include <linux/usb/typec_dp.h>
+#include "displayport.h"
+
+static int nvidia_altmode_probe(struct typec_altmode *alt)
+{
+	if (alt->svid == USB_TYPEC_NVIDIA_VLINK_SID)
+		return dp_altmode_probe(alt);
+	else
+		return -ENOTSUPP;
+}
+
+static void nvidia_altmode_remove(struct typec_altmode *alt)
+{
+	if (alt->svid == USB_TYPEC_NVIDIA_VLINK_SID)
+		dp_altmode_remove(alt);
+}
+
+static const struct typec_device_id nvidia_typec_id[] = {
+	{ USB_TYPEC_NVIDIA_VLINK_SID, TYPEC_ANY_MODE },
+	{ },
+};
+MODULE_DEVICE_TABLE(typec, nvidia_typec_id);
+
+static struct typec_altmode_driver nvidia_altmode_driver = {
+	.id_table = nvidia_typec_id,
+	.probe = nvidia_altmode_probe,
+	.remove = nvidia_altmode_remove,
+	.driver = {
+		.name = "typec_nvidia",
+		.owner = THIS_MODULE,
+	},
+};
+module_typec_altmode_driver(nvidia_altmode_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("NVIDIA USB Type-C Alt Mode Driver");

drivers/usb/typec/ucsi/ucsi.c

@@ -283,6 +283,7 @@ static int ucsi_register_altmode(struct ucsi_connector *con,
 
 		switch (desc->svid) {
 		case USB_TYPEC_DP_SID:
+		case USB_TYPEC_NVIDIA_VLINK_SID:
 			alt = ucsi_register_displayport(con, override, i, desc);
 			break;
 		default:
@@ -404,7 +405,8 @@ 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_DP_SID ||
+			adev[i]->svid == USB_TYPEC_NVIDIA_VLINK_SID)) {
 			pdev = typec_altmode_get_partner(adev[i]);
 			ucsi_displayport_remove_partner((void *)pdev);
 		}

include/linux/usb/typec_dp.h

@@ -5,6 +5,11 @@
 #include <linux/usb/typec_altmode.h>
 
 #define USB_TYPEC_DP_SID	0xff01
+/* USB IF has not assigned a Standard ID (SID) for VirtualLink,
+ * so the manufacturers of VirtualLink adapters use their Vendor
+ * IDs as the SVID.
+ */
+#define USB_TYPEC_NVIDIA_VLINK_SID	0x955	/* NVIDIA VirtualLink */
 #define USB_TYPEC_DP_MODE	1
 
 /*