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From:   Heikki Krogerus <heikki.krogerus@linux.intel.com>
To:     Guenter Roeck <linux@roeck-us.net>,
        Hans de Goede <hdegoede@redhat.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jun Li <jun.li@nxp.com>,
        Mats Karrman <mats.dev.list@gmail.com>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH v4 6/8] usb: typec: Add driver for DisplayPort alternate mode
Date:   Fri,  8 Jun 2018 14:29:39 +0300
Message-Id: <20180608112941.26332-7-heikki.krogerus@linux.intel.com>
In-Reply-To: <20180608112941.26332-1-heikki.krogerus@linux.intel.com>
References: <20180608112941.26332-1-heikki.krogerus@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

DisplayPort USB Type-C Alt Mode allows DisplayPort displays
and adapters to be attached to the USB Type-C ports on the
system.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
 .../testing/sysfs-driver-typec-displayport    |  49 ++
 drivers/usb/typec/Kconfig                     |   2 +
 drivers/usb/typec/Makefile                    |   1 +
 drivers/usb/typec/altmodes/Kconfig            |  14 +
 drivers/usb/typec/altmodes/Makefile           |   2 +
 drivers/usb/typec/altmodes/displayport.c      | 543 ++++++++++++++++++
 include/linux/usb/typec_dp.h                  |  70 +++
 7 files changed, 681 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-typec-displayport
 create mode 100644 drivers/usb/typec/altmodes/Kconfig
 create mode 100644 drivers/usb/typec/altmodes/Makefile
 create mode 100644 drivers/usb/typec/altmodes/displayport.c
 create mode 100644 include/linux/usb/typec_dp.h

diff --git a/Documentation/ABI/testing/sysfs-driver-typec-displayport b/Documentation/ABI/testing/sysfs-driver-typec-displayport
new file mode 100644
index 000000000000..66d72185cfd5
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-typec-displayport
@@ -0,0 +1,49 @@
+What:		/sys/bus/typec/devices/.../displayport/configuration
+Date:		July 2018
+Contact:	Heikki Krogerus <heikki.krogerus@linux.intel.com>
+Description:
+		Shows the current DisplayPort configuration for the connector.
+		Valid values are USB, source and sink. Source means DisplayPort
+		source, and sink means DisplayPort sink.
+
+		All supported configurations are listed as space separated list
+		with the active one wrapped in square brackets.
+
+		Source example:
+
+			USB [source] sink
+
+		The configuration can be changed by writing to the file
+
+		Note. USB configuration does not equal to Exit Mode. It is
+		separate configuration defined in VESA DisplayPort Alt Mode on
+		USB Type-C Standard. Functionally it equals to the situation
+		where the mode has been exited (to exit the mode, see
+		Documentation/ABI/testing/sysfs-bus-typec, and use file
+		/sys/bus/typec/devices/.../active).
+
+What:		/sys/bus/typec/devices/.../displayport/pin_assignment
+Date:		July 2018
+Contact:	Heikki Krogerus <heikki.krogerus@linux.intel.com>
+Description:
+		VESA DisplayPort Alt Mode on USB Type-C Standard defines six
+		different pin assignments for USB Type-C connector that are
+		labeled A, B, C, D, E, and F. The supported pin assignments are
+		listed as space separated list with the active one wrapped in
+		square brackets.
+
+		Example:
+
+			C [D]
+
+		Pin assignment can be changed by writing to the file. It is
+		possible to set pin assignment before configuration has been
+		set, but the assignment will not be active before the
+		connector is actually configured.
+
+		Note. As of VESA DisplayPort Alt Mode on USB Type-C Standard
+		version 1.0b, pin assignments A, B, and F are deprecated. Only
+		pin assignments D can now carry simultaneously one channel of
+		USB SuperSpeed protocol. From user perspective pin assignments C
+		and E are equal, where all channels on the connector are used
+		for carrying DisplayPort protocol (allowing higher resolutions).
diff --git a/drivers/usb/typec/Kconfig b/drivers/usb/typec/Kconfig
index 2c8eab11a493..652d49ede8b8 100644
--- a/drivers/usb/typec/Kconfig
+++ b/drivers/usb/typec/Kconfig
@@ -88,4 +88,6 @@ config TYPEC_TPS6598X
 
 source "drivers/usb/typec/mux/Kconfig"
 
+source "drivers/usb/typec/altmodes/Kconfig"
+
 endif # TYPEC
diff --git a/drivers/usb/typec/Makefile b/drivers/usb/typec/Makefile
index 5466c62c8e97..65651ec65d19 100644
--- a/drivers/usb/typec/Makefile
+++ b/drivers/usb/typec/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_TYPEC)		+= typec.o
 typec-y				:= class.o mux.o bus.o
+obj-$(CONFIG_TYPEC)		+= altmodes/
 obj-$(CONFIG_TYPEC_TCPM)	+= tcpm.o
 obj-y				+= fusb302/
 obj-$(CONFIG_TYPEC_WCOVE)	+= typec_wcove.o
diff --git a/drivers/usb/typec/altmodes/Kconfig b/drivers/usb/typec/altmodes/Kconfig
new file mode 100644
index 000000000000..efef2a64bc51
--- /dev/null
+++ b/drivers/usb/typec/altmodes/Kconfig
@@ -0,0 +1,14 @@
+
+menu "USB Type-C Alternate Mode drivers"
+
+config TYPEC_DP_ALTMODE
+	tristate "DisplayPort Alternate Mode driver"
+	help
+	  DisplayPort USB Type-C Alternate Mode allows DisplayPort
+	  displays and adapters to be attached to the USB Type-C
+	  connectors on the system.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called typec_displayport.
+
+endmenu
diff --git a/drivers/usb/typec/altmodes/Makefile b/drivers/usb/typec/altmodes/Makefile
new file mode 100644
index 000000000000..5caf094ef71a
--- /dev/null
+++ b/drivers/usb/typec/altmodes/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_TYPEC_DP_ALTMODE)		+= typec_displayport.o
+typec_displayport-y			:= displayport.o
diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
new file mode 100644
index 000000000000..a5054d86a4d9
--- /dev/null
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -0,0 +1,543 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * USB Typec-C DisplayPort Alternate Mode driver
+ *
+ * Copyright (C) 2018 Intel Corporation
+ * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+ *
+ * DisplayPort is trademark of VESA (www.vesa.org)
+ */
+
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/usb/pd_vdo.h>
+#include <linux/usb/typec_dp.h>
+
+#define DP_HEADER(cmd)			(VDO(USB_TYPEC_DP_SID, 1, cmd) | \
+					 VDO_OPOS(USB_TYPEC_DP_MODE))
+
+/* DisplayPort alt mode specific commands */
+#define DP_CMD_STATUS_UPDATE		VDO_CMD_VENDOR(0)
+#define DP_CMD_CONFIGURE		VDO_CMD_VENDOR(1)
+
+enum {
+	DP_CONF_USB,
+	DP_CONF_DFP_D,
+	DP_CONF_UFP_D,
+	DP_CONF_DUAL_D,
+};
+
+/* DisplayPort Capabilities VDO bits */
+#define DP_CAP_CAPABILITY(_cap_)	((_cap_) & 3)
+#define   DP_CAP_UFP_D			1
+#define   DP_CAP_DFP_D			2
+#define   DP_CAP_DFP_D_AND_UFP_D	3
+#define DP_CAP_DP_SIGNALING		BIT(2) /* Always set */
+#define DP_CAP_GEN2			BIT(3) /* Reserved after v1.0b */
+#define DP_CAP_RECEPTACLE		BIT(6)
+#define DP_CAP_USB			BIT(7)
+#define DP_CAP_DFP_D_PIN_ASSIGN(_cap_)	(((_cap_) & GENMASK(15, 8)) >> 8)
+#define DP_CAP_UFP_D_PIN_ASSIGN(_cap_)	(((_cap_) & GENMASK(23, 16)) >> 16)
+
+enum {
+	DP_PIN_ASSIGN_A, /* Not supported after v1.0b */
+	DP_PIN_ASSIGN_B, /* Not supported after v1.0b */
+	DP_PIN_ASSIGN_C,
+	DP_PIN_ASSIGN_D,
+	DP_PIN_ASSIGN_E,
+	DP_PIN_ASSIGN_F, /* Not supported after v1.0b */
+};
+
+/* Helper for setting/getting the pin assignement value to the configuration */
+#define DP_CONF_SET_PIN_ASSIGN(_a_)	((_a_) << 8)
+#define DP_CONF_GET_PIN_ASSIGN(_conf_)	(((_conf_) & GENMASK(15, 8)) >> 8)
+
+/* Pin assignments that use USB3.1 Gen2 signaling to carry DP protocol */
+#define DP_PIN_ASSIGN_GEN2_BR_MASK	(BIT(DP_PIN_ASSIGN_A) | \
+					 BIT(DP_PIN_ASSIGN_B))
+
+/* Pin assignments that use DP v1.3 signaling to carry DP protocol */
+#define DP_PIN_ASSIGN_DP_BR_MASK	(BIT(DP_PIN_ASSIGN_C) | \
+					 BIT(DP_PIN_ASSIGN_D) | \
+					 BIT(DP_PIN_ASSIGN_E) | \
+					 BIT(DP_PIN_ASSIGN_F))
+
+/* DP only pin assignments */
+#define DP_PIN_ASSIGN_DP_ONLY_MASK	(BIT(DP_PIN_ASSIGN_A) | \
+					 BIT(DP_PIN_ASSIGN_C) | \
+					 BIT(DP_PIN_ASSIGN_E))
+
+/* Pin assignments where one channel is for USB */
+#define DP_PIN_ASSIGN_MULTI_FUNC_MASK	(BIT(DP_PIN_ASSIGN_B) | \
+					 BIT(DP_PIN_ASSIGN_D) | \
+					 BIT(DP_PIN_ASSIGN_F))
+
+enum dp_state {
+	DP_STATE_NONE,
+	DP_STATE_ENTER,
+	DP_STATE_UPDATE,
+	DP_STATE_CONFIGURE,
+	DP_STATE_EXIT,
+};
+
+struct dp_altmode {
+	struct typec_displayport_data data;
+
+	enum dp_state state;
+
+	struct mutex lock;
+	struct work_struct work;
+	struct typec_altmode *alt;
+	const struct typec_altmode *port;
+};
+
+static int dp_altmode_configure(struct dp_altmode *dp, u8 con)
+{
+	u32 conf = DP_CONF_SIGNALING_DP; /* Only DP signaling supported */
+	u8 pin_assign = 0;
+
+	switch (con) {
+	case DP_STATUS_CON_DISABLED:
+		dp->data.conf = 0;
+		return 0;
+	case DP_STATUS_CON_DFP_D:
+		conf |= DP_CONF_UFP_U_AS_DFP_D;
+		pin_assign = DP_CAP_UFP_D_PIN_ASSIGN(dp->alt->vdo) &
+			     DP_CAP_DFP_D_PIN_ASSIGN(dp->port->vdo);
+		break;
+	case DP_STATUS_CON_UFP_D:
+	case DP_STATUS_CON_BOTH: /* NOTE: First acting as DP source */
+		conf |= DP_CONF_UFP_U_AS_UFP_D;
+		pin_assign = DP_CAP_DFP_D_PIN_ASSIGN(dp->alt->vdo) &
+			     DP_CAP_UFP_D_PIN_ASSIGN(dp->port->vdo);
+		break;
+	default:
+		break;
+	}
+
+	/* Determining the initial pin assignment. */
+	if (!DP_CONF_GET_PIN_ASSIGN(dp->data.conf)) {
+		/* Is USB together with DP preferred */
+		if (dp->data.status & DP_STATUS_PREFER_MULTI_FUNC &&
+		    pin_assign & DP_PIN_ASSIGN_MULTI_FUNC_MASK)
+			pin_assign &= DP_PIN_ASSIGN_MULTI_FUNC_MASK;
+		else
+			pin_assign &= DP_PIN_ASSIGN_DP_ONLY_MASK;
+
+		if (!pin_assign)
+			return -EINVAL;
+
+		conf |= DP_CONF_SET_PIN_ASSIGN(pin_assign);
+	}
+
+	dp->data.conf |= conf;
+
+	return 0;
+}
+
+static int dp_altmode_status_update(struct dp_altmode *dp)
+{
+	bool configured = !!DP_CONF_GET_PIN_ASSIGN(dp->data.conf);
+	u8 con = DP_STATUS_CONNECTION(dp->data.status);
+	int ret = 0;
+
+	if (configured && (dp->data.status & DP_STATUS_SWITCH_TO_USB)) {
+		dp->data.conf = 0;
+		dp->state = DP_STATE_CONFIGURE;
+	} else if (dp->data.status & DP_STATUS_EXIT_DP_MODE) {
+		dp->state = DP_STATE_EXIT;
+	} else if (!(con & DP_CONF_CURRENTLY(dp->data.conf))) {
+		ret = dp_altmode_configure(dp, con);
+		if (!ret)
+			dp->state = DP_STATE_CONFIGURE;
+	}
+
+	return ret;
+}
+
+static int dp_altmode_configured(struct dp_altmode *dp)
+{
+	u8 state;
+	int ret;
+
+	sysfs_notify(&dp->alt->dev.kobj, "displayport", "configuration");
+
+	if (!dp->data.conf)
+		return typec_altmode_notify(dp->alt, TYPEC_STATE_USB,
+					    &dp->data);
+
+	state = get_count_order(DP_CONF_GET_PIN_ASSIGN(dp->data.conf));
+	ret = typec_altmode_notify(dp->alt, TYPEC_MODAL_STATE(state),
+				   &dp->data);
+	if (ret)
+		return ret;
+
+	sysfs_notify(&dp->alt->dev.kobj, "displayport", "pin_assignment");
+
+	return 0;
+}
+
+static void dp_altmode_work(struct work_struct *work)
+{
+	struct dp_altmode *dp = container_of(work, struct dp_altmode, work);
+	u32 header = 0;
+	u32 vdo;
+	int ret;
+
+	mutex_lock(&dp->lock);
+
+	switch (dp->state) {
+	case DP_STATE_ENTER:
+		ret = typec_altmode_enter(dp->alt);
+		if (ret)
+			dev_err(&dp->alt->dev, "failed to enter mode\n");
+		break;
+	case DP_STATE_UPDATE:
+		header = DP_HEADER(DP_CMD_STATUS_UPDATE);
+		vdo = 1;
+		break;
+	case DP_STATE_CONFIGURE:
+		ret = typec_altmode_notify(dp->alt, TYPEC_STATE_SAFE,
+					   &dp->data);
+		if (ret) {
+			dev_err(&dp->alt->dev,
+				"unable to put to connector to safe mode\n");
+			break;
+		}
+		header = DP_HEADER(DP_CMD_CONFIGURE);
+		vdo = dp->data.conf;
+		break;
+	case DP_STATE_EXIT:
+		if (typec_altmode_exit(dp->alt))
+			dev_err(&dp->alt->dev, "Exit Mode Failed!\n");
+		break;
+	default:
+		break;
+	}
+
+	if (header) {
+		if (typec_altmode_vdm(dp->alt, header, &vdo, 2))
+			dev_err(&dp->alt->dev, "unable to send VDM\n");
+	}
+
+	mutex_unlock(&dp->lock);
+}
+
+static void dp_altmode_attention(struct typec_altmode *alt, const u32 vdo)
+{
+	struct dp_altmode *dp = typec_altmode_get_drvdata(alt);
+	u8 state;
+
+	mutex_lock(&dp->lock);
+
+	dp->state = DP_STATE_NONE;
+	dp->data.status = vdo;
+	dp_altmode_status_update(dp);
+
+	if (dp->state == DP_STATE_NONE) {
+		state = get_count_order(DP_CONF_GET_PIN_ASSIGN(dp->data.conf));
+		if (typec_altmode_notify(dp->alt, TYPEC_MODAL_STATE(state),
+					 &dp->data))
+			dev_err(&alt->dev, "%s: notification failed\n",
+				__func__);
+	} else {
+		schedule_work(&dp->work);
+	}
+
+	mutex_unlock(&dp->lock);
+}
+
+static int dp_altmode_vdm(struct typec_altmode *alt,
+			  const u32 hdr, const u32 *vdo, int count)
+{
+	struct dp_altmode *dp = typec_altmode_get_drvdata(alt);
+	int cmd_type = PD_VDO_CMDT(hdr);
+	int cmd = PD_VDO_CMD(hdr);
+	int ret = 0;
+
+	mutex_lock(&dp->lock);
+
+	dp->state = DP_STATE_NONE;
+
+	switch (cmd_type) {
+	case CMDT_RSP_ACK:
+		switch (cmd) {
+		case CMD_ENTER_MODE:
+			dp->state = DP_STATE_UPDATE;
+			break;
+		case CMD_EXIT_MODE:
+			dp->data.status = 0;
+			dp->data.conf = 0;
+			break;
+		case DP_CMD_STATUS_UPDATE:
+			dp->data.status = *vdo;
+			ret = dp_altmode_status_update(dp);
+			break;
+		case DP_CMD_CONFIGURE:
+			ret = dp_altmode_configured(dp);
+			break;
+		default:
+			break;
+		}
+		break;
+	case CMDT_RSP_NAK:
+		switch (cmd) {
+		case DP_CMD_CONFIGURE:
+			dp->data.conf = 0;
+			ret = dp_altmode_configured(dp);
+			break;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	if (dp->state != DP_STATE_NONE)
+		schedule_work(&dp->work);
+
+	mutex_unlock(&dp->lock);
+	return ret;
+}
+
+static int dp_altmode_activate(struct typec_altmode *alt, int activate)
+{
+	return activate ? typec_altmode_enter(alt) : typec_altmode_exit(alt);
+}
+
+static const struct typec_altmode_ops dp_altmode_ops = {
+	.attention = dp_altmode_attention,
+	.vdm = dp_altmode_vdm,
+	.activate = dp_altmode_activate,
+};
+
+static const char * const configurations[] = {
+	[DP_CONF_USB]	= "USB",
+	[DP_CONF_DFP_D]	= "source",
+	[DP_CONF_UFP_D]	= "sink",
+};
+
+static ssize_t
+configuration_store(struct device *dev, struct device_attribute *attr,
+		    const char *buf, size_t size)
+{
+	struct dp_altmode *dp = dev_get_drvdata(dev);
+	int conf;
+	int ret;
+
+	conf = sysfs_match_string(configurations, buf);
+	if (conf < 0)
+		return conf;
+
+	mutex_lock(&dp->lock);
+
+	ret = dp_altmode_configure(dp, conf);
+	if (!ret && dp->alt->active) {
+		dp->state = DP_STATE_CONFIGURE;
+		schedule_work(&dp->work);
+	}
+
+	mutex_unlock(&dp->lock);
+
+	return ret ? ret : size;
+}
+
+static ssize_t configuration_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct dp_altmode *dp = dev_get_drvdata(dev);
+	int len;
+	u8 cap;
+	u8 cur;
+	int i;
+
+	mutex_lock(&dp->lock);
+
+	cap = DP_CAP_CAPABILITY(dp->alt->vdo);
+	cur = DP_CONF_CURRENTLY(dp->data.conf);
+
+	len = sprintf(buf, "%s ", cur ? "USB" : "[USB]");
+
+	for (i = 1; i < ARRAY_SIZE(configurations); i++) {
+		if (i == cur)
+			len += sprintf(buf + len, "[%s] ", configurations[i]);
+		else if ((i == DP_CONF_DFP_D && cap & DP_CAP_DFP_D) ||
+			 (i == DP_CONF_UFP_D && cap & DP_CAP_UFP_D))
+			len += sprintf(buf + len, "%s ", configurations[i]);
+	}
+
+	mutex_unlock(&dp->lock);
+
+	buf[len - 1] = '\n';
+	return len;
+}
+static DEVICE_ATTR_RW(configuration);
+
+static const char * const pin_assignments[] = {
+	[DP_PIN_ASSIGN_A] = "A",
+	[DP_PIN_ASSIGN_B] = "B",
+	[DP_PIN_ASSIGN_C] = "C",
+	[DP_PIN_ASSIGN_D] = "D",
+	[DP_PIN_ASSIGN_E] = "E",
+	[DP_PIN_ASSIGN_F] = "F",
+};
+
+static ssize_t
+pin_assignment_store(struct device *dev, struct device_attribute *attr,
+		     const char *buf, size_t size)
+{
+	struct dp_altmode *dp = dev_get_drvdata(dev);
+	u8 assignments;
+	u32 conf;
+	int ret;
+
+	ret = sysfs_match_string(pin_assignments, buf);
+	if (ret < 0)
+		return ret;
+
+	conf = DP_CONF_SET_PIN_ASSIGN(BIT(ret));
+	ret = 0;
+
+	mutex_lock(&dp->lock);
+
+	if (conf & dp->data.conf)
+		goto out_unlock;
+
+	if (DP_CONF_CURRENTLY(dp->data.conf) == DP_CONF_DFP_D)
+		assignments = DP_CAP_UFP_D_PIN_ASSIGN(dp->alt->vdo);
+	else
+		assignments = DP_CAP_DFP_D_PIN_ASSIGN(dp->alt->vdo);
+
+	if (!(DP_CONF_GET_PIN_ASSIGN(conf) & assignments)) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	/* Only send Configure command if a configuration has been set */
+	if (dp->alt->active && DP_CONF_CURRENTLY(dp->data.conf)) {
+		dp->state = DP_STATE_CONFIGURE;
+		schedule_work(&dp->work);
+	}
+
+	dp->data.conf &= ~DP_CONF_PIN_ASSIGNEMENT_MASK;
+	dp->data.conf |= conf;
+
+out_unlock:
+	mutex_unlock(&dp->lock);
+
+	return ret ? ret : size;
+}
+
+static ssize_t pin_assignment_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct dp_altmode *dp = dev_get_drvdata(dev);
+	u8 assignments;
+	int len = 0;
+	u8 cur;
+	int i;
+
+	mutex_lock(&dp->lock);
+
+	cur = get_count_order(DP_CONF_GET_PIN_ASSIGN(dp->data.conf));
+
+	if (DP_CONF_CURRENTLY(dp->data.conf) == DP_CONF_DFP_D)
+		assignments = DP_CAP_UFP_D_PIN_ASSIGN(dp->alt->vdo);
+	else
+		assignments = DP_CAP_DFP_D_PIN_ASSIGN(dp->alt->vdo);
+
+	for (i = 0; assignments; assignments >>= 1, i++) {
+		if (assignments & 1) {
+			if (i == cur)
+				len += sprintf(buf + len, "[%s] ",
+					       pin_assignments[i]);
+			else
+				len += sprintf(buf + len, "%s ",
+					       pin_assignments[i]);
+		}
+	}
+
+	mutex_unlock(&dp->lock);
+
+	buf[len - 1] = '\n';
+	return len;
+}
+static DEVICE_ATTR_RW(pin_assignment);
+
+static struct attribute *dp_altmode_attrs[] = {
+	&dev_attr_configuration.attr,
+	&dev_attr_pin_assignment.attr,
+	NULL
+};
+
+static const struct attribute_group dp_altmode_group = {
+	.name = "displayport",
+	.attrs = dp_altmode_attrs,
+};
+
+static int dp_altmode_probe(struct typec_altmode *alt)
+{
+	const struct typec_altmode *port = typec_altmode_get_partner(alt);
+	struct dp_altmode *dp;
+	int ret;
+
+	/* FIXME: Port can only be DFP_U. */
+
+	/* Make sure we have compatiple pin configurations */
+	if (!(DP_CAP_DFP_D_PIN_ASSIGN(port->vdo) &
+	      DP_CAP_UFP_D_PIN_ASSIGN(alt->vdo)) &&
+	    !(DP_CAP_UFP_D_PIN_ASSIGN(port->vdo) &
+	      DP_CAP_DFP_D_PIN_ASSIGN(alt->vdo)))
+		return -ENODEV;
+
+	ret = sysfs_create_group(&alt->dev.kobj, &dp_altmode_group);
+	if (ret)
+		return ret;
+
+	dp = devm_kzalloc(&alt->dev, sizeof(*dp), GFP_KERNEL);
+	if (!dp)
+		return -ENOMEM;
+
+	INIT_WORK(&dp->work, dp_altmode_work);
+	mutex_init(&dp->lock);
+	dp->port = port;
+	dp->alt = alt;
+
+	alt->desc = "DisplayPort";
+	alt->ops = &dp_altmode_ops;
+
+	typec_altmode_set_drvdata(alt, dp);
+
+	dp->state = DP_STATE_ENTER;
+	schedule_work(&dp->work);
+
+	return 0;
+}
+
+static void dp_altmode_remove(struct typec_altmode *alt)
+{
+	sysfs_remove_group(&alt->dev.kobj, &dp_altmode_group);
+}
+
+static const struct typec_device_id dp_typec_id[] = {
+	{ USB_TYPEC_DP_SID, USB_TYPEC_DP_MODE },
+	{ },
+};
+MODULE_DEVICE_TABLE(typec, dp_typec_id);
+
+static struct typec_altmode_driver dp_altmode_driver = {
+	.id_table = dp_typec_id,
+	.probe = dp_altmode_probe,
+	.remove = dp_altmode_remove,
+	.driver = {
+		.name = "typec_displayport",
+		.owner = THIS_MODULE,
+	},
+};
+module_typec_altmode_driver(dp_altmode_driver);
+
+MODULE_AUTHOR("Heikki Krogerus <heikki.krogerus@linux.intel.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("DisplayPort Alternate Mode");
diff --git a/include/linux/usb/typec_dp.h b/include/linux/usb/typec_dp.h
new file mode 100644
index 000000000000..5ca989076d7c
--- /dev/null
+++ b/include/linux/usb/typec_dp.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __USB_TYPEC_DP_H
+#define __USB_TYPEC_DP_H
+
+#include <linux/usb/typec_altmode.h>
+
+#define USB_TYPEC_DP_SID	0xff01
+#define USB_TYPEC_DP_MODE	1
+
+/*
+ * Connector states matching the pin assignments in DisplayPort Alt Mode
+ * Specification.
+ *
+ * These values are meant primarily to be used by the mux drivers, but they are
+ * also used as the "value" part in the alternate mode notification chain, so
+ * receivers of those notifications will always see them.
+ *
+ * Note. DisplayPort USB Type-C Alt Mode Specification version 1.0b deprecated
+ * pin assignments A, B and F, but they are still defined here for legacy
+ * purposes.
+ */
+enum {
+	TYPEC_DP_STATE_A = TYPEC_STATE_MODAL,	/* Not supported after v1.0b */
+	TYPEC_DP_STATE_B,			/* Not supported after v1.0b */
+	TYPEC_DP_STATE_C,
+	TYPEC_DP_STATE_D,
+	TYPEC_DP_STATE_E,
+	TYPEC_DP_STATE_F,			/* Not supported after v1.0b */
+};
+
+/*
+ * struct typec_displayport_data - DisplayPort Alt Mode specific data
+ * @status: Status Update command VDO content
+ * @conf: Configure command VDO content
+ *
+ * This structure is delivered as the data part with the notifications. It
+ * contains the VDOs from the two DisplayPort Type-C alternate mode specific
+ * commands: Status Update and Configure.
+ *
+ * @status will show for example the status of the HPD signal.
+ */
+struct typec_displayport_data {
+	u32 status;
+	u32 conf;
+};
+
+/* DisplayPort Status Update VDO bits */
+#define DP_STATUS_CONNECTION(_status_)	((_status_) & 3)
+#define   DP_STATUS_CON_DISABLED	0
+#define   DP_STATUS_CON_DFP_D		1
+#define   DP_STATUS_CON_UFP_D		2
+#define   DP_STATUS_CON_BOTH		3
+#define DP_STATUS_POWER_LOW		BIT(2)
+#define DP_STATUS_ENABLED		BIT(3)
+#define DP_STATUS_PREFER_MULTI_FUNC	BIT(4)
+#define DP_STATUS_SWITCH_TO_USB		BIT(5)
+#define DP_STATUS_EXIT_DP_MODE		BIT(6)
+#define DP_STATUS_HPD_STATE		BIT(7) /* 0 = HPD_Low, 1 = HPD_High */
+#define DP_STATUS_IRQ_HPD		BIT(8)
+
+/* DisplayPort Configurations VDO bits */
+#define DP_CONF_CURRENTLY(_conf_)	((_conf_) & 3)
+#define DP_CONF_UFP_U_AS_DFP_D		BIT(0)
+#define DP_CONF_UFP_U_AS_UFP_D		BIT(1)
+#define DP_CONF_SIGNALING_DP		BIT(2)
+#define DP_CONF_SIGNALING_GEN_2		BIT(3) /* Reserved after v1.0b */
+#define DP_CONF_PIN_ASSIGNEMENT_SHIFT	8
+#define DP_CONF_PIN_ASSIGNEMENT_MASK	GENMASK(15, 8)
+
+#endif /* __USB_TYPEC_DP_H */
-- 
2.17.1