text: // 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>
  #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_UPDATE,
  	DP_STATE_CONFIGURE,
  	DP_STATE_EXIT,
  };
  
  struct dp_altmode {
  	struct typec_displayport_data data;
  
  	enum dp_state state;
  
  	struct mutex lock; /* device lock */
  	struct work_struct work;
  	struct typec_altmode *alt;
  	const struct typec_altmode *port;
  };
  
  static int dp_altmode_notify(struct dp_altmode *dp)
  {
  	u8 state = get_count_order(DP_CONF_GET_PIN_ASSIGN(dp->data.conf));
  
  	return typec_altmode_notify(dp->alt, TYPEC_MODAL_STATE(state),
  				   &dp->data);
  }
  
  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:
  		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 if (pin_assign & DP_PIN_ASSIGN_DP_ONLY_MASK)
  			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)
  {
  	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);
  
  	ret = dp_altmode_notify(dp);
  	if (ret)
  		return ret;
  
  	sysfs_notify(&dp->alt->dev.kobj, "displayport", "pin_assignment");
  
  	return 0;
  }
  
  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) {
  		if (DP_CONF_GET_PIN_ASSIGN(dp->data.conf))
  			dp_altmode_notify(dp);
  		else
  			typec_altmode_notify(dp->alt, TYPEC_STATE_USB,
  					     &dp->data);
  	}
  
  	return ret;
  }
  
  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_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_EXIT:
  		if (typec_altmode_exit(dp->alt))
  			dev_err(&dp->alt->dev, "Exit Mode Failed!\n");
  		break;
  	default:
  		break;
  	}
  
  	dp->state = DP_STATE_IDLE;
  
  	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:
  			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_IDLE)
  		schedule_work(&dp->work);
  
  err_unlock:
  	mutex_unlock(&dp->lock);
  	return ret;
  }
  
  static int dp_altmode_activate(struct typec_altmode *alt, int activate)
  {
  	return activate ? typec_altmode_enter(alt, NULL) :
  			  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);
  	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",
  };
  
  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;
  	}
  
  	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;
  	}
  
  	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)) {
  		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));
  
  	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,
  };
  
  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;
  }
  EXPORT_SYMBOL_GPL(dp_altmode_probe);
  
  void dp_altmode_remove(struct typec_altmode *alt)
  {
  	struct dp_altmode *dp = typec_altmode_get_drvdata(alt);
  
  	sysfs_remove_group(&alt->dev.kobj, &dp_altmode_group);
  	cancel_work_sync(&dp->work);
  }
  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",
  		.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");
  