drivers/usb/typec/altmodes/displayport.c - linux - Git at Google

 // 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/property.h>
 #include <linux/usb/pd_vdo.h>
 #include <linux/usb/typec_dp.h>
 #include <drm/drm_connector.h>
 #include "displayport.h"

 #define DP_HEADER(_dp, ver, cmd)	(VDO((_dp)->alt->svid, 1, ver, cmd)	\
 					 | VDO_OPOS(USB_TYPEC_DP_MODE))

 enum {
 	DP_CONF_USB,
 	DP_CONF_DFP_D,
 	DP_CONF_UFP_D,
 	DP_CONF_DUAL_D,
 };

 /* 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_IDLE,
 	DP_STATE_ENTER,
 	DP_STATE_ENTER_PRIME,
 	DP_STATE_UPDATE,
 	DP_STATE_CONFIGURE,
 	DP_STATE_CONFIGURE_PRIME,
 	DP_STATE_EXIT,
 	DP_STATE_EXIT_PRIME,
 };

 struct dp_altmode {
 	struct typec_displayport_data data;
 	struct typec_displayport_data data_prime;

 	enum dp_state state;
 	bool hpd;
 	bool pending_hpd;

 	struct mutex lock; /* device lock */
 	struct work_struct work;
 	struct typec_altmode *alt;
 	const struct typec_altmode *port;
 	struct fwnode_handle *connector_fwnode;
 	struct typec_altmode *plug_prime;
 };

 static int dp_altmode_notify(struct dp_altmode *dp)
 {
 	unsigned long conf;
 	u8 state;

 	if (dp->data.conf) {
 		state = get_count_order(DP_CONF_GET_PIN_ASSIGN(dp->data.conf));
 		conf = TYPEC_MODAL_STATE(state);
 	} else {
 		conf = TYPEC_STATE_USB;
 	}

 	return typec_altmode_notify(dp->alt, conf, &dp->data);
 }

 static int dp_altmode_configure(struct dp_altmode *dp, u8 con)
 {
 	u8 pin_assign = 0;
 	u32 conf;

 	/* DP Signalling */
 	conf = (dp->data.conf & DP_CONF_SIGNALLING_MASK) >> DP_CONF_SIGNALLING_SHIFT;

 	switch (con) {
 	case DP_STATUS_CON_DISABLED:
 		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);
 		/* Account for active cable capabilities */
 		if (dp->plug_prime)
 			pin_assign &= DP_CAP_DFP_D_PIN_ASSIGN(dp->plug_prime->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_PIN_ASSIGN_UFP_D(dp->alt->vdo) &
 				 DP_CAP_PIN_ASSIGN_DFP_D(dp->port->vdo);
 		/* Account for active cable capabilities */
 		if (dp->plug_prime)
 			pin_assign &= DP_CAP_UFP_D_PIN_ASSIGN(dp->plug_prime->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 if (pin_assign & DP_PIN_ASSIGN_DP_ONLY_MASK) {
 			pin_assign &= DP_PIN_ASSIGN_DP_ONLY_MASK;
 			/* Default to pin assign C if available */
 			if (pin_assign & BIT(DP_PIN_ASSIGN_C))
 				pin_assign = BIT(DP_PIN_ASSIGN_C);
 		}

 		if (!pin_assign)
 			return -EINVAL;

 		conf |= DP_CONF_SET_PIN_ASSIGN(pin_assign);
 	}

 	dp->data.conf = conf;
 	if (dp->plug_prime)
 		dp->data_prime.conf = conf;

 	return 0;
 }

 static int dp_altmode_status_update(struct dp_altmode *dp)
 {
 	bool configured = !!DP_CONF_GET_PIN_ASSIGN(dp->data.conf);
 	bool hpd = !!(dp->data.status & DP_STATUS_HPD_STATE);
 	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->data_prime.conf = 0;
 		dp->state = dp->plug_prime ? DP_STATE_CONFIGURE_PRIME :
 					     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->plug_prime ? DP_STATE_CONFIGURE_PRIME :
 						     DP_STATE_CONFIGURE;
 			if (dp->hpd != hpd) {
 				dp->hpd = hpd;
 				dp->pending_hpd = true;
 			}
 		}
 	} else {
 		drm_connector_oob_hotplug_event(dp->connector_fwnode,
 						hpd ? connector_status_connected :
 						      connector_status_disconnected);
 		dp->hpd = hpd;
 		sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
 	}

 	return ret;
 }

 static int dp_altmode_configured(struct dp_altmode *dp)
 {
 	sysfs_notify(&dp->alt->dev.kobj, "displayport", "configuration");
 	sysfs_notify(&dp->alt->dev.kobj, "displayport", "pin_assignment");
 	/*
 	 * If the DFP_D/UFP_D sends a change in HPD when first notifying the
 	 * DisplayPort driver that it is connected, then we wait until
 	 * configuration is complete to signal HPD.
 	 */
 	if (dp->pending_hpd) {
 		drm_connector_oob_hotplug_event(dp->connector_fwnode,
 						connector_status_connected);
 		sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
 		dp->pending_hpd = false;
 	}

 	return dp_altmode_notify(dp);
 }

 static int dp_altmode_configure_vdm(struct dp_altmode *dp, u32 conf)
 {
 	int svdm_version = typec_altmode_get_svdm_version(dp->alt);
 	u32 header;
 	int ret;

 	if (svdm_version < 0)
 		return svdm_version;

 	header = DP_HEADER(dp, svdm_version, DP_CMD_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");
 		return ret;
 	}

 	ret = typec_altmode_vdm(dp->alt, header, &conf, 2);
 	if (ret)
 		dp_altmode_notify(dp);

 	return ret;
 }

 static int dp_altmode_configure_vdm_cable(struct dp_altmode *dp, u32 conf)
 {
 	int svdm_version = typec_altmode_get_cable_svdm_version(dp->plug_prime);
 	u32 header;

 	if (svdm_version < 0)
 		return svdm_version;

 	header = DP_HEADER(dp, svdm_version, DP_CMD_CONFIGURE);

 	return typec_cable_altmode_vdm(dp->plug_prime, TYPEC_PLUG_SOP_P, header, &conf, 2);
 }

 static void dp_altmode_work(struct work_struct *work)
 {
 	struct dp_altmode *dp = container_of(work, struct dp_altmode, work);
 	int svdm_version;
 	u32 header;
 	u32 vdo;
 	int ret;

 	mutex_lock(&dp->lock);

 	switch (dp->state) {
 	case DP_STATE_ENTER:
 		ret = typec_altmode_enter(dp->alt, NULL);
 		if (ret && ret != -EBUSY)
 			dev_err(&dp->alt->dev, "failed to enter mode\n");
 		break;
 	case DP_STATE_ENTER_PRIME:
 		ret = typec_cable_altmode_enter(dp->alt, TYPEC_PLUG_SOP_P, NULL);
 		/*
 		 * If we fail to enter Alt Mode on SOP', then we should drop the
 		 * plug from the driver and attempt to run the driver without
 		 * it.
 		 */
 		if (ret && ret != -EBUSY) {
 			dev_err(&dp->alt->dev, "plug failed to enter mode\n");
 			dp->state = DP_STATE_ENTER;
 			goto disable_prime;
 		}
 		break;
 	case DP_STATE_UPDATE:
 		svdm_version = typec_altmode_get_svdm_version(dp->alt);
 		if (svdm_version < 0)
 			break;
 		header = DP_HEADER(dp, svdm_version, DP_CMD_STATUS_UPDATE);
 		vdo = 1;
 		ret = typec_altmode_vdm(dp->alt, header, &vdo, 2);
 		if (ret)
 			dev_err(&dp->alt->dev,
 				"unable to send Status Update command (%d)\n",
 				ret);
 		break;
 	case DP_STATE_CONFIGURE:
 		ret = dp_altmode_configure_vdm(dp, dp->data.conf);
 		if (ret)
 			dev_err(&dp->alt->dev,
 				"unable to send Configure command (%d)\n", ret);
 		break;
 	case DP_STATE_CONFIGURE_PRIME:
 		ret = dp_altmode_configure_vdm_cable(dp, dp->data_prime.conf);
 		if (ret) {
 			dev_err(&dp->plug_prime->dev,
 				"unable to send Configure command (%d)\n",
 				ret);
 			dp->state = DP_STATE_CONFIGURE;
 			goto disable_prime;
 		}
 		break;
 	case DP_STATE_EXIT:
 		if (typec_altmode_exit(dp->alt))
 			dev_err(&dp->alt->dev, "Exit Mode Failed!\n");
 		break;
 	case DP_STATE_EXIT_PRIME:
 		if (typec_cable_altmode_exit(dp->plug_prime, TYPEC_PLUG_SOP_P))
 			dev_err(&dp->plug_prime->dev, "Exit Mode Failed!\n");
 		break;
 	default:
 		break;
 	}

 	dp->state = DP_STATE_IDLE;

 	mutex_unlock(&dp->lock);
 	return;

 disable_prime:
 	typec_altmode_put_plug(dp->plug_prime);
 	dp->plug_prime = NULL;
 	schedule_work(&dp->work);
 	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 old_state;

 	mutex_lock(&dp->lock);

 	old_state = dp->state;
 	dp->data.status = vdo;

 	if (old_state != DP_STATE_IDLE)
 		dev_warn(&alt->dev, "ATTENTION while processing state %d\n",
 			 old_state);

 	if (dp_altmode_status_update(dp))
 		dev_warn(&alt->dev, "%s: status update failed\n", __func__);

 	if (dp_altmode_notify(dp))
 		dev_err(&alt->dev, "%s: notification failed\n", __func__);

 	if (old_state == DP_STATE_IDLE && dp->state != DP_STATE_IDLE)
 		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);

 	if (dp->state != DP_STATE_IDLE) {
 		ret = -EBUSY;
 		goto err_unlock;
 	}

 	switch (cmd_type) {
 	case CMDT_RSP_ACK:
 		switch (cmd) {
 		case CMD_ENTER_MODE:
 			typec_altmode_update_active(alt, true);
 			dp->state = DP_STATE_UPDATE;
 			break;
 		case CMD_EXIT_MODE:
 			typec_altmode_update_active(alt, false);
 			dp->data.status = 0;
 			dp->data.conf = 0;
 			if (dp->hpd) {
 				drm_connector_oob_hotplug_event(dp->connector_fwnode,
 								connector_status_disconnected);
 				dp->hpd = false;
 				sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
 			}
 			if (dp->plug_prime)
 				dp->state = DP_STATE_EXIT_PRIME;
 			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_IDLE)
 		schedule_work(&dp->work);

 err_unlock:
 	mutex_unlock(&dp->lock);
 	return ret;
 }

 static int dp_cable_altmode_vdm(struct typec_altmode *alt, enum typec_plug_index sop,
 				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);

 	if (dp->state != DP_STATE_IDLE) {
 		ret = -EBUSY;
 		goto err_unlock;
 	}

 	switch (cmd_type) {
 	case CMDT_RSP_ACK:
 		switch (cmd) {
 		case CMD_ENTER_MODE:
 			typec_altmode_update_active(dp->plug_prime, true);
 			dp->state = DP_STATE_ENTER;
 			break;
 		case CMD_EXIT_MODE:
 			dp->data_prime.status = 0;
 			dp->data_prime.conf = 0;
 			typec_altmode_update_active(dp->plug_prime, false);
 			break;
 		case DP_CMD_CONFIGURE:
 			dp->state = DP_STATE_CONFIGURE;
 			break;
 		default:
 			break;
 		}
 		break;
 	case CMDT_RSP_NAK:
 		switch (cmd) {
 		case DP_CMD_CONFIGURE:
 			dp->data_prime.conf = 0;
 			/* Attempt to configure on SOP, drop plug */
 			typec_altmode_put_plug(dp->plug_prime);
 			dp->plug_prime = NULL;
 			dp->state = DP_STATE_CONFIGURE;
 			break;
 		default:
 			break;
 		}
 		break;
 	default:
 		break;
 	}

 	if (dp->state != DP_STATE_IDLE)
 		schedule_work(&dp->work);

 err_unlock:
 	mutex_unlock(&dp->lock);
 	return ret;
 }

 static int dp_altmode_activate(struct typec_altmode *alt, int activate)
 {
 	struct dp_altmode *dp = typec_altmode_get_drvdata(alt);
 	int ret;

 	if (activate) {
 		if (dp->plug_prime) {
 			ret = typec_cable_altmode_enter(alt, TYPEC_PLUG_SOP_P, NULL);
 			if (ret < 0) {
 				typec_altmode_put_plug(dp->plug_prime);
 				dp->plug_prime = NULL;
 			} else {
 				return ret;
 			}
 		}
 		return typec_altmode_enter(alt, NULL);
 	} else {
 		return 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 struct typec_cable_ops dp_cable_ops = {
 	.vdm = dp_cable_altmode_vdm,
 };

 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);
 	u32 conf;
 	u32 cap;
 	int con;
 	int ret = 0;

 	con = sysfs_match_string(configurations, buf);
 	if (con < 0)
 		return con;

 	mutex_lock(&dp->lock);

 	if (dp->state != DP_STATE_IDLE) {
 		ret = -EBUSY;
 		goto err_unlock;
 	}

 	cap = DP_CAP_CAPABILITY(dp->alt->vdo);

 	if ((con == DP_CONF_DFP_D && !(cap & DP_CAP_DFP_D)) ||
 	    (con == DP_CONF_UFP_D && !(cap & DP_CAP_UFP_D))) {
 		ret = -EINVAL;
 		goto err_unlock;
 	}

 	conf = dp->data.conf & ~DP_CONF_DUAL_D;
 	conf |= con;

 	if (dp->alt->active) {
 		ret = dp_altmode_configure_vdm(dp, conf);
 		if (ret)
 			goto err_unlock;
 	}

 	dp->data.conf = conf;

 err_unlock:
 	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",
 };

 /*
  * Helper function to extract a peripheral's currently supported
  * Pin Assignments from its DisplayPort alternate mode state.
  */
 static u8 get_current_pin_assignments(struct dp_altmode *dp)
 {
 	if (DP_CONF_CURRENTLY(dp->data.conf) == DP_CONF_UFP_U_AS_DFP_D)
 		return DP_CAP_PIN_ASSIGN_DFP_D(dp->alt->vdo);
 	else
 		return DP_CAP_PIN_ASSIGN_UFP_D(dp->alt->vdo);
 }

 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->state != DP_STATE_IDLE) {
 		ret = -EBUSY;
 		goto out_unlock;
 	}

 	assignments = get_current_pin_assignments(dp);

 	if (!(DP_CONF_GET_PIN_ASSIGN(conf) & assignments)) {
 		ret = -EINVAL;
 		goto out_unlock;
 	}

 	conf |= dp->data.conf & ~DP_CONF_PIN_ASSIGNEMENT_MASK;

 	/* Only send Configure command if a configuration has been set */
 	if (dp->alt->active && DP_CONF_CURRENTLY(dp->data.conf)) {
 		/* todo: send manual configure over SOP'*/
 		ret = dp_altmode_configure_vdm(dp, conf);
 		if (ret)
 			goto out_unlock;
 	}

 	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));

 	assignments = get_current_pin_assignments(dp);

 	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);

 	/* get_current_pin_assignments can return 0 when no matching pin assignments are found */
 	if (len == 0)
 		len++;

 	buf[len - 1] = '\n';
 	return len;
 }
 static DEVICE_ATTR_RW(pin_assignment);

 static ssize_t hpd_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct dp_altmode *dp = dev_get_drvdata(dev);

 	return sysfs_emit(buf, "%d\n", dp->hpd);
 }
 static DEVICE_ATTR_RO(hpd);

 static struct attribute *displayport_attrs[] = {
 	&dev_attr_configuration.attr,
 	&dev_attr_pin_assignment.attr,
 	&dev_attr_hpd.attr,
 	NULL
 };

 static const struct attribute_group displayport_group = {
 	.name = "displayport",
 	.attrs = displayport_attrs,
 };

 static const struct attribute_group *displayport_groups[] = {
 	&displayport_group,
 	NULL,
 };

 int dp_altmode_probe(struct typec_altmode *alt)
 {
 	const struct typec_altmode *port = typec_altmode_get_partner(alt);
 	struct typec_altmode *plug = typec_altmode_get_plug(alt, TYPEC_PLUG_SOP_P);
 	struct fwnode_handle *fwnode;
 	struct dp_altmode *dp;

 	/* FIXME: Port can only be DFP_U. */

 	/* Make sure we have compatiple pin configurations */
 	if (!(DP_CAP_PIN_ASSIGN_DFP_D(port->vdo) &
 	      DP_CAP_PIN_ASSIGN_UFP_D(alt->vdo)) &&
 	    !(DP_CAP_PIN_ASSIGN_UFP_D(port->vdo) &
 	      DP_CAP_PIN_ASSIGN_DFP_D(alt->vdo)))
 		return -ENODEV;

 	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";
 	typec_altmode_set_ops(alt, &dp_altmode_ops);

 	if (plug) {
 		plug->desc = "Displayport";
 		plug->cable_ops = &dp_cable_ops;
 	}

 	dp->plug_prime = plug;

 	fwnode = dev_fwnode(alt->dev.parent->parent); /* typec_port fwnode */
 	if (fwnode_property_present(fwnode, "displayport"))
 		dp->connector_fwnode = fwnode_find_reference(fwnode, "displayport", 0);
 	else
 		dp->connector_fwnode = fwnode_handle_get(fwnode); /* embedded DP */
 	if (IS_ERR(dp->connector_fwnode))
 		dp->connector_fwnode = NULL;

 	typec_altmode_set_drvdata(alt, dp);
 	if (plug)
 		typec_altmode_set_drvdata(plug, dp);

 	dp->state = plug ? DP_STATE_ENTER_PRIME : DP_STATE_ENTER;
 	schedule_work(&dp->work);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(dp_altmode_probe);

 void dp_altmode_remove(struct typec_altmode *alt)
 {
 	struct dp_altmode *dp = typec_altmode_get_drvdata(alt);

 	cancel_work_sync(&dp->work);
 	typec_altmode_put_plug(dp->plug_prime);

 	if (dp->connector_fwnode) {
 		drm_connector_oob_hotplug_event(dp->connector_fwnode,
 						connector_status_disconnected);

 		fwnode_handle_put(dp->connector_fwnode);
 	}
 }
 EXPORT_SYMBOL_GPL(dp_altmode_remove);

 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",
 		.dev_groups = displayport_groups,
 	},
 };
 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");
	// 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/property.h>
	#include <linux/usb/pd_vdo.h>
	#include <linux/usb/typec_dp.h>
	#include <drm/drm_connector.h>
	#include "displayport.h"

	#define DP_HEADER(_dp, ver, cmd) (VDO((_dp)->alt->svid, 1, ver, cmd) \
	\| VDO_OPOS(USB_TYPEC_DP_MODE))

	enum {
	DP_CONF_USB,
	DP_CONF_DFP_D,
	DP_CONF_UFP_D,
	DP_CONF_DUAL_D,
	};

	/* 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_IDLE,
	DP_STATE_ENTER,
	DP_STATE_ENTER_PRIME,
	DP_STATE_UPDATE,
	DP_STATE_CONFIGURE,
	DP_STATE_CONFIGURE_PRIME,
	DP_STATE_EXIT,
	DP_STATE_EXIT_PRIME,
	};

	struct dp_altmode {
	struct typec_displayport_data data;
	struct typec_displayport_data data_prime;

	enum dp_state state;
	bool hpd;
	bool pending_hpd;

	struct mutex lock; /* device lock */
	struct work_struct work;
	struct typec_altmode *alt;
	const struct typec_altmode *port;
	struct fwnode_handle *connector_fwnode;
	struct typec_altmode *plug_prime;
	};

	static int dp_altmode_notify(struct dp_altmode *dp)
	{
	unsigned long conf;
	u8 state;

	if (dp->data.conf) {
	state = get_count_order(DP_CONF_GET_PIN_ASSIGN(dp->data.conf));
	conf = TYPEC_MODAL_STATE(state);
	} else {
	conf = TYPEC_STATE_USB;
	}

	return typec_altmode_notify(dp->alt, conf, &dp->data);
	}

	static int dp_altmode_configure(struct dp_altmode *dp, u8 con)
	{
	u8 pin_assign = 0;
	u32 conf;

	/* DP Signalling */
	conf = (dp->data.conf & DP_CONF_SIGNALLING_MASK) >> DP_CONF_SIGNALLING_SHIFT;

	switch (con) {
	case DP_STATUS_CON_DISABLED:
	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);
	/* Account for active cable capabilities */
	if (dp->plug_prime)
	pin_assign &= DP_CAP_DFP_D_PIN_ASSIGN(dp->plug_prime->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_PIN_ASSIGN_UFP_D(dp->alt->vdo) &
	DP_CAP_PIN_ASSIGN_DFP_D(dp->port->vdo);
	/* Account for active cable capabilities */
	if (dp->plug_prime)
	pin_assign &= DP_CAP_UFP_D_PIN_ASSIGN(dp->plug_prime->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 if (pin_assign & DP_PIN_ASSIGN_DP_ONLY_MASK) {
	pin_assign &= DP_PIN_ASSIGN_DP_ONLY_MASK;
	/* Default to pin assign C if available */
	if (pin_assign & BIT(DP_PIN_ASSIGN_C))
	pin_assign = BIT(DP_PIN_ASSIGN_C);
	}

	if (!pin_assign)
	return -EINVAL;

	conf \|= DP_CONF_SET_PIN_ASSIGN(pin_assign);
	}

	dp->data.conf = conf;
	if (dp->plug_prime)
	dp->data_prime.conf = conf;

	return 0;
	}

	static int dp_altmode_status_update(struct dp_altmode *dp)
	{
	bool configured = !!DP_CONF_GET_PIN_ASSIGN(dp->data.conf);
	bool hpd = !!(dp->data.status & DP_STATUS_HPD_STATE);
	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->data_prime.conf = 0;
	dp->state = dp->plug_prime ? DP_STATE_CONFIGURE_PRIME :
	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->plug_prime ? DP_STATE_CONFIGURE_PRIME :
	DP_STATE_CONFIGURE;
	if (dp->hpd != hpd) {
	dp->hpd = hpd;
	dp->pending_hpd = true;
	}
	}
	} else {
	drm_connector_oob_hotplug_event(dp->connector_fwnode,
	hpd ? connector_status_connected :
	connector_status_disconnected);
	dp->hpd = hpd;
	sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
	}

	return ret;
	}

	static int dp_altmode_configured(struct dp_altmode *dp)
	{
	sysfs_notify(&dp->alt->dev.kobj, "displayport", "configuration");
	sysfs_notify(&dp->alt->dev.kobj, "displayport", "pin_assignment");
	/*
	* If the DFP_D/UFP_D sends a change in HPD when first notifying the
	* DisplayPort driver that it is connected, then we wait until
	* configuration is complete to signal HPD.
	*/
	if (dp->pending_hpd) {
	drm_connector_oob_hotplug_event(dp->connector_fwnode,
	connector_status_connected);
	sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
	dp->pending_hpd = false;
	}

	return dp_altmode_notify(dp);
	}

	static int dp_altmode_configure_vdm(struct dp_altmode *dp, u32 conf)
	{
	int svdm_version = typec_altmode_get_svdm_version(dp->alt);
	u32 header;
	int ret;

	if (svdm_version < 0)
	return svdm_version;

	header = DP_HEADER(dp, svdm_version, DP_CMD_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");
	return ret;
	}

	ret = typec_altmode_vdm(dp->alt, header, &conf, 2);
	if (ret)
	dp_altmode_notify(dp);

	return ret;
	}

	static int dp_altmode_configure_vdm_cable(struct dp_altmode *dp, u32 conf)
	{
	int svdm_version = typec_altmode_get_cable_svdm_version(dp->plug_prime);
	u32 header;

	if (svdm_version < 0)
	return svdm_version;

	header = DP_HEADER(dp, svdm_version, DP_CMD_CONFIGURE);

	return typec_cable_altmode_vdm(dp->plug_prime, TYPEC_PLUG_SOP_P, header, &conf, 2);
	}

	static void dp_altmode_work(struct work_struct *work)
	{
	struct dp_altmode *dp = container_of(work, struct dp_altmode, work);
	int svdm_version;
	u32 header;
	u32 vdo;
	int ret;

	mutex_lock(&dp->lock);

	switch (dp->state) {
	case DP_STATE_ENTER:
	ret = typec_altmode_enter(dp->alt, NULL);
	if (ret && ret != -EBUSY)
	dev_err(&dp->alt->dev, "failed to enter mode\n");
	break;
	case DP_STATE_ENTER_PRIME:
	ret = typec_cable_altmode_enter(dp->alt, TYPEC_PLUG_SOP_P, NULL);
	/*
	* If we fail to enter Alt Mode on SOP', then we should drop the
	* plug from the driver and attempt to run the driver without
	* it.
	*/
	if (ret && ret != -EBUSY) {
	dev_err(&dp->alt->dev, "plug failed to enter mode\n");
	dp->state = DP_STATE_ENTER;
	goto disable_prime;
	}
	break;
	case DP_STATE_UPDATE:
	svdm_version = typec_altmode_get_svdm_version(dp->alt);
	if (svdm_version < 0)
	break;
	header = DP_HEADER(dp, svdm_version, DP_CMD_STATUS_UPDATE);
	vdo = 1;
	ret = typec_altmode_vdm(dp->alt, header, &vdo, 2);
	if (ret)
	dev_err(&dp->alt->dev,
	"unable to send Status Update command (%d)\n",
	ret);
	break;
	case DP_STATE_CONFIGURE:
	ret = dp_altmode_configure_vdm(dp, dp->data.conf);
	if (ret)
	dev_err(&dp->alt->dev,
	"unable to send Configure command (%d)\n", ret);
	break;
	case DP_STATE_CONFIGURE_PRIME:
	ret = dp_altmode_configure_vdm_cable(dp, dp->data_prime.conf);
	if (ret) {
	dev_err(&dp->plug_prime->dev,
	"unable to send Configure command (%d)\n",
	ret);
	dp->state = DP_STATE_CONFIGURE;
	goto disable_prime;
	}
	break;
	case DP_STATE_EXIT:
	if (typec_altmode_exit(dp->alt))
	dev_err(&dp->alt->dev, "Exit Mode Failed!\n");
	break;
	case DP_STATE_EXIT_PRIME:
	if (typec_cable_altmode_exit(dp->plug_prime, TYPEC_PLUG_SOP_P))
	dev_err(&dp->plug_prime->dev, "Exit Mode Failed!\n");
	break;
	default:
	break;
	}

	dp->state = DP_STATE_IDLE;

	mutex_unlock(&dp->lock);
	return;

	disable_prime:
	typec_altmode_put_plug(dp->plug_prime);
	dp->plug_prime = NULL;
	schedule_work(&dp->work);
	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 old_state;

	mutex_lock(&dp->lock);

	old_state = dp->state;
	dp->data.status = vdo;

	if (old_state != DP_STATE_IDLE)
	dev_warn(&alt->dev, "ATTENTION while processing state %d\n",
	old_state);

	if (dp_altmode_status_update(dp))
	dev_warn(&alt->dev, "%s: status update failed\n", __func__);

	if (dp_altmode_notify(dp))
	dev_err(&alt->dev, "%s: notification failed\n", __func__);

	if (old_state == DP_STATE_IDLE && dp->state != DP_STATE_IDLE)
	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);

	if (dp->state != DP_STATE_IDLE) {
	ret = -EBUSY;
	goto err_unlock;
	}

	switch (cmd_type) {
	case CMDT_RSP_ACK:
	switch (cmd) {
	case CMD_ENTER_MODE:
	typec_altmode_update_active(alt, true);
	dp->state = DP_STATE_UPDATE;
	break;
	case CMD_EXIT_MODE:
	typec_altmode_update_active(alt, false);
	dp->data.status = 0;
	dp->data.conf = 0;
	if (dp->hpd) {
	drm_connector_oob_hotplug_event(dp->connector_fwnode,
	connector_status_disconnected);
	dp->hpd = false;
	sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
	}
	if (dp->plug_prime)
	dp->state = DP_STATE_EXIT_PRIME;
	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_IDLE)
	schedule_work(&dp->work);

	err_unlock:
	mutex_unlock(&dp->lock);
	return ret;
	}

	static int dp_cable_altmode_vdm(struct typec_altmode *alt, enum typec_plug_index sop,
	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);

	if (dp->state != DP_STATE_IDLE) {
	ret = -EBUSY;
	goto err_unlock;
	}

	switch (cmd_type) {
	case CMDT_RSP_ACK:
	switch (cmd) {
	case CMD_ENTER_MODE:
	typec_altmode_update_active(dp->plug_prime, true);
	dp->state = DP_STATE_ENTER;
	break;
	case CMD_EXIT_MODE:
	dp->data_prime.status = 0;
	dp->data_prime.conf = 0;
	typec_altmode_update_active(dp->plug_prime, false);
	break;
	case DP_CMD_CONFIGURE:
	dp->state = DP_STATE_CONFIGURE;
	break;
	default:
	break;
	}
	break;
	case CMDT_RSP_NAK:
	switch (cmd) {
	case DP_CMD_CONFIGURE:
	dp->data_prime.conf = 0;
	/* Attempt to configure on SOP, drop plug */
	typec_altmode_put_plug(dp->plug_prime);
	dp->plug_prime = NULL;
	dp->state = DP_STATE_CONFIGURE;
	break;
	default:
	break;
	}
	break;
	default:
	break;
	}

	if (dp->state != DP_STATE_IDLE)
	schedule_work(&dp->work);

	err_unlock:
	mutex_unlock(&dp->lock);
	return ret;
	}

	static int dp_altmode_activate(struct typec_altmode *alt, int activate)
	{
	struct dp_altmode *dp = typec_altmode_get_drvdata(alt);
	int ret;

	if (activate) {
	if (dp->plug_prime) {
	ret = typec_cable_altmode_enter(alt, TYPEC_PLUG_SOP_P, NULL);
	if (ret < 0) {
	typec_altmode_put_plug(dp->plug_prime);
	dp->plug_prime = NULL;
	} else {
	return ret;
	}
	}
	return typec_altmode_enter(alt, NULL);
	} else {
	return 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 struct typec_cable_ops dp_cable_ops = {
	.vdm = dp_cable_altmode_vdm,
	};

	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);
	u32 conf;
	u32 cap;
	int con;
	int ret = 0;

	con = sysfs_match_string(configurations, buf);
	if (con < 0)
	return con;

	mutex_lock(&dp->lock);

	if (dp->state != DP_STATE_IDLE) {
	ret = -EBUSY;
	goto err_unlock;
	}

	cap = DP_CAP_CAPABILITY(dp->alt->vdo);

	if ((con == DP_CONF_DFP_D && !(cap & DP_CAP_DFP_D)) \|\|
	(con == DP_CONF_UFP_D && !(cap & DP_CAP_UFP_D))) {
	ret = -EINVAL;
	goto err_unlock;
	}

	conf = dp->data.conf & ~DP_CONF_DUAL_D;
	conf \|= con;

	if (dp->alt->active) {
	ret = dp_altmode_configure_vdm(dp, conf);
	if (ret)
	goto err_unlock;
	}

	dp->data.conf = conf;

	err_unlock:
	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",
	};

	/*
	* Helper function to extract a peripheral's currently supported
	* Pin Assignments from its DisplayPort alternate mode state.
	*/
	static u8 get_current_pin_assignments(struct dp_altmode *dp)
	{
	if (DP_CONF_CURRENTLY(dp->data.conf) == DP_CONF_UFP_U_AS_DFP_D)
	return DP_CAP_PIN_ASSIGN_DFP_D(dp->alt->vdo);
	else
	return DP_CAP_PIN_ASSIGN_UFP_D(dp->alt->vdo);
	}

	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->state != DP_STATE_IDLE) {
	ret = -EBUSY;
	goto out_unlock;
	}

	assignments = get_current_pin_assignments(dp);

	if (!(DP_CONF_GET_PIN_ASSIGN(conf) & assignments)) {
	ret = -EINVAL;
	goto out_unlock;
	}

	conf \|= dp->data.conf & ~DP_CONF_PIN_ASSIGNEMENT_MASK;

	/* Only send Configure command if a configuration has been set */
	if (dp->alt->active && DP_CONF_CURRENTLY(dp->data.conf)) {
	/* todo: send manual configure over SOP'*/
	ret = dp_altmode_configure_vdm(dp, conf);
	if (ret)
	goto out_unlock;
	}

	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));

	assignments = get_current_pin_assignments(dp);

	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);

	/* get_current_pin_assignments can return 0 when no matching pin assignments are found */
	if (len == 0)
	len++;

	buf[len - 1] = '\n';
	return len;
	}
	static DEVICE_ATTR_RW(pin_assignment);

	static ssize_t hpd_show(struct device dev, struct device_attribute attr, char *buf)
	{
	struct dp_altmode *dp = dev_get_drvdata(dev);

	return sysfs_emit(buf, "%d\n", dp->hpd);
	}
	static DEVICE_ATTR_RO(hpd);

	static struct attribute *displayport_attrs[] = {
	&dev_attr_configuration.attr,
	&dev_attr_pin_assignment.attr,
	&dev_attr_hpd.attr,
	NULL
	};

	static const struct attribute_group displayport_group = {
	.name = "displayport",
	.attrs = displayport_attrs,
	};

	static const struct attribute_group *displayport_groups[] = {
	&displayport_group,
	NULL,
	};

	int dp_altmode_probe(struct typec_altmode *alt)
	{
	const struct typec_altmode *port = typec_altmode_get_partner(alt);
	struct typec_altmode *plug = typec_altmode_get_plug(alt, TYPEC_PLUG_SOP_P);
	struct fwnode_handle *fwnode;
	struct dp_altmode *dp;

	/* FIXME: Port can only be DFP_U. */

	/* Make sure we have compatiple pin configurations */
	if (!(DP_CAP_PIN_ASSIGN_DFP_D(port->vdo) &
	DP_CAP_PIN_ASSIGN_UFP_D(alt->vdo)) &&
	!(DP_CAP_PIN_ASSIGN_UFP_D(port->vdo) &
	DP_CAP_PIN_ASSIGN_DFP_D(alt->vdo)))
	return -ENODEV;

	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";
	typec_altmode_set_ops(alt, &dp_altmode_ops);

	if (plug) {
	plug->desc = "Displayport";
	plug->cable_ops = &dp_cable_ops;
	}

	dp->plug_prime = plug;

	fwnode = dev_fwnode(alt->dev.parent->parent); /* typec_port fwnode */
	if (fwnode_property_present(fwnode, "displayport"))
	dp->connector_fwnode = fwnode_find_reference(fwnode, "displayport", 0);
	else
	dp->connector_fwnode = fwnode_handle_get(fwnode); /* embedded DP */
	if (IS_ERR(dp->connector_fwnode))
	dp->connector_fwnode = NULL;

	typec_altmode_set_drvdata(alt, dp);
	if (plug)
	typec_altmode_set_drvdata(plug, dp);

	dp->state = plug ? DP_STATE_ENTER_PRIME : DP_STATE_ENTER;
	schedule_work(&dp->work);

	return 0;
	}
	EXPORT_SYMBOL_GPL(dp_altmode_probe);

	void dp_altmode_remove(struct typec_altmode *alt)
	{
	struct dp_altmode *dp = typec_altmode_get_drvdata(alt);

	cancel_work_sync(&dp->work);
	typec_altmode_put_plug(dp->plug_prime);

	if (dp->connector_fwnode) {
	drm_connector_oob_hotplug_event(dp->connector_fwnode,
	connector_status_disconnected);

	fwnode_handle_put(dp->connector_fwnode);
	}
	}
	EXPORT_SYMBOL_GPL(dp_altmode_remove);

	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",
	.dev_groups = displayport_groups,
	},
	};
	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");