// SPDX-License-Identifier: GPL-2.0

  /*

   * Copyright � 2010 - 2015 UNISYS CORPORATION

   * All rights reserved.

   */

  #include <linux/ctype.h>

  #include <linux/debugfs.h>

  #include <linux/module.h>
  #include <linux/slab.h>

  #include <linux/visorbus.h>

  #include <linux/uuid.h>

  #include "visorbus_private.h"

  static const guid_t visor_vbus_channel_guid = VISOR_VBUS_CHANNEL_GUID;

  /* Display string that is guaranteed to be no longer the 99 characters */

  #define LINESIZE 99

  #define POLLJIFFIES_NORMALCHANNEL 10

  /* stores whether bus_registration was successful */
  static bool initialized;

  static struct dentry *visorbus_debugfs_dir;

  /*

   * DEVICE type attributes
   *
   * The modalias file will contain the guid of the device.
   */
  static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
  			     char *buf)
  {
  	struct visor_device *vdev;

  	const guid_t *guid;

  
  	vdev = to_visor_device(dev);

  	guid = visorchannel_get_guid(vdev->visorchannel);
  	return sprintf(buf, "visorbus:%pUl
  ", guid);

  }
  static DEVICE_ATTR_RO(modalias);
  
  static struct attribute *visorbus_dev_attrs[] = {
  	&dev_attr_modalias.attr,
  	NULL,
  };

  ATTRIBUTE_GROUPS(visorbus_dev);

  /* filled in with info about parent chipset driver when we register with it */

  static struct visor_vbus_deviceinfo chipset_driverinfo;

  /* filled in with info about this driver, wrt it servicing client busses */

  static struct visor_vbus_deviceinfo clientbus_driverinfo;

  /* list of visor_device structs, linked via .list_all */

  static LIST_HEAD(list_all_bus_instances);

  /* list of visor_device structs, linked via .list_all */

  static LIST_HEAD(list_all_device_instances);

  /*
   * Generic function useful for validating any type of channel when it is
   * received by the client that will be accessing the channel.
   * Note that <logCtx> is only needed for callers in the EFI environment, and
   * is used to pass the EFI_DIAG_CAPTURE_PROTOCOL needed to log messages.
   */

  int visor_check_channel(struct channel_header *ch, struct device *dev,
  			const guid_t *expected_guid, char *chname,
  			u64 expected_min_bytes, u32 expected_version,

  			u64 expected_signature)
  {

  	if (!guid_is_null(expected_guid)) {

  		/* caller wants us to verify type GUID */

  		if (!guid_equal(&ch->chtype, expected_guid)) {

  			dev_err(dev, "Channel mismatch on channel=%s(%pUL) field=type expected=%pUL actual=%pUL
  ",
  				chname, expected_guid, expected_guid,
  				&ch->chtype);

  			return 0;
  		}
  	}
  	/* verify channel size */
  	if (expected_min_bytes > 0) {
  		if (ch->size < expected_min_bytes) {

  			dev_err(dev, "Channel mismatch on channel=%s(%pUL) field=size expected=0x%-8.8Lx actual=0x%-8.8Lx
  ",
  				chname, expected_guid,
  				(unsigned long long)expected_min_bytes,
  				ch->size);

  			return 0;
  		}
  	}
  	/* verify channel version */
  	if (expected_version > 0) {
  		if (ch->version_id != expected_version) {

  			dev_err(dev, "Channel mismatch on channel=%s(%pUL) field=version expected=0x%-8.8lx actual=0x%-8.8x
  ",
  				chname, expected_guid,
  				(unsigned long)expected_version,
  				ch->version_id);

  			return 0;
  		}
  	}
  	/* verify channel signature */
  	if (expected_signature > 0) {
  		if (ch->signature != expected_signature) {

  			dev_err(dev, "Channel mismatch on channel=%s(%pUL) field=signature expected=0x%-8.8Lx actual=0x%-8.8Lx
  ",
  				chname, expected_guid,	expected_signature,
  				ch->signature);

  			return 0;
  		}
  	}
  	return 1;
  }

  static int visorbus_uevent(struct device *xdev, struct kobj_uevent_env *env)

  {

  	struct visor_device *dev;

  	const guid_t *guid;

  
  	dev = to_visor_device(xdev);

  	guid = visorchannel_get_guid(dev->visorchannel);

  	return add_uevent_var(env, "MODALIAS=visorbus:%pUl", guid);

  }

  /*

   * visorbus_match() - called automatically upon adding a visor_device
   *                    (device_add), or adding a visor_driver
   *                    (visorbus_register_visor_driver)
   * @xdev: struct device for the device being matched
   * @xdrv: struct device_driver for driver to match device against
   *
   * Return: 1 iff the provided driver can control the specified device

   */

  static int visorbus_match(struct device *xdev, struct device_driver *xdrv)

  {

  	const guid_t *channel_type;

  	int i;
  	struct visor_device *dev;
  	struct visor_driver *drv;

  	struct visorchannel *chan;

  
  	dev = to_visor_device(xdev);

  	channel_type = visorchannel_get_guid(dev->visorchannel);

  	drv = to_visor_driver(xdrv);

  	chan = dev->visorchannel;

  	if (!drv->channel_types)

  		return 0;

  	for (i = 0; !guid_is_null(&drv->channel_types[i].guid); i++)

  		if (guid_equal(&drv->channel_types[i].guid, channel_type) &&
  		    visor_check_channel(visorchannel_get_header(chan),
  					xdev,
  					&drv->channel_types[i].guid,
  					(char *)drv->channel_types[i].name,
  					drv->channel_types[i].min_bytes,
  					drv->channel_types[i].version,
  					VISOR_CHANNEL_SIGNATURE))

  			return i + 1;

  	return 0;

  }

  /*
   * This describes the TYPE of bus.

   * (Don't confuse this with an INSTANCE of the bus.)

   */

  static struct bus_type visorbus_type = {

  	.name = "visorbus",
  	.match = visorbus_match,
  	.uevent = visorbus_uevent,
  	.dev_groups = visorbus_dev_groups,

  };

  struct visor_busdev {
  	u32 bus_no;
  	u32 dev_no;
  };

  static int match_visorbus_dev_by_id(struct device *dev, const void *data)

  {
  	struct visor_device *vdev = to_visor_device(dev);

  	const struct visor_busdev *id = data;

  	if (vdev->chipset_bus_no == id->bus_no &&
  	    vdev->chipset_dev_no == id->dev_no)

  		return 1;
  	return 0;
  }
  
  struct visor_device *visorbus_get_device_by_id(u32 bus_no, u32 dev_no,
  					       struct visor_device *from)
  {
  	struct device *dev;
  	struct device *dev_start = NULL;
  	struct visor_busdev id = {
  		.bus_no = bus_no,
  		.dev_no = dev_no
  	};
  
  	if (from)
  		dev_start = &from->device;
  	dev = bus_find_device(&visorbus_type, dev_start, (void *)&id,
  			      match_visorbus_dev_by_id);
  	if (!dev)
  		return NULL;
  	return to_visor_device(dev);
  }

  /*

   * visorbus_release_busdevice() - called when device_unregister() is called for
   *                                the bus device instance, after all other tasks
   *                                involved with destroying the dev are complete

   * @xdev: struct device for the bus being released

   */

  static void visorbus_release_busdevice(struct device *xdev)

  {

  	struct visor_device *dev = dev_get_drvdata(xdev);

  	debugfs_remove(dev->debugfs_bus_info);

  	debugfs_remove_recursive(dev->debugfs_dir);

  	visorchannel_destroy(dev->visorchannel);

  	kfree(dev);

  }

  /*

   * visorbus_release_device() - called when device_unregister() is called for
   *                             each child device instance
   * @xdev: struct device for the visor device being released

   */

  static void visorbus_release_device(struct device *xdev)

  {
  	struct visor_device *dev = to_visor_device(xdev);

  	visorchannel_destroy(dev->visorchannel);

  	kfree(dev);
  }

  /*

   * BUS specific channel attributes to appear under

   * /sys/bus/visorbus<x>/dev<y>/channel
   */

  static ssize_t physaddr_show(struct device *dev, struct device_attribute *attr,
  			     char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);

  	return sprintf(buf, "0x%llx
  ",
  		       visorchannel_get_physaddr(vdev->visorchannel));

  }

  static DEVICE_ATTR_RO(physaddr);

  static ssize_t nbytes_show(struct device *dev, struct device_attribute *attr,
  			   char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);

  	return sprintf(buf, "0x%lx
  ",

  		       visorchannel_get_nbytes(vdev->visorchannel));

  }

  static DEVICE_ATTR_RO(nbytes);

  static ssize_t clientpartition_show(struct device *dev,
  				    struct device_attribute *attr, char *buf)
  {
  	struct visor_device *vdev = to_visor_device(dev);

  	return sprintf(buf, "0x%llx
  ",
  		       visorchannel_get_clientpartition(vdev->visorchannel));

  }

  static DEVICE_ATTR_RO(clientpartition);

  static ssize_t typeguid_show(struct device *dev, struct device_attribute *attr,
  			     char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);

  	char typeid[LINESIZE];

  	return sprintf(buf, "%s
  ",
  		       visorchannel_id(vdev->visorchannel, typeid));

  }

  static DEVICE_ATTR_RO(typeguid);

  static ssize_t zoneguid_show(struct device *dev, struct device_attribute *attr,
  			     char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);

  	char zoneid[LINESIZE];

  	return sprintf(buf, "%s
  ",
  		       visorchannel_zoneid(vdev->visorchannel, zoneid));

  }

  static DEVICE_ATTR_RO(zoneguid);

  static ssize_t typename_show(struct device *dev, struct device_attribute *attr,
  			     char *buf)

  {
  	int i = 0;

  	struct bus_type *xbus = dev->bus;
  	struct device_driver *xdrv = dev->driver;

  	struct visor_driver *drv = NULL;

  	if (!xdrv)

  		return 0;

  	i = xbus->match(dev, xdrv);

  	if (!i)
  		return 0;
  	drv = to_visor_driver(xdrv);

  	return sprintf(buf, "%s
  ", drv->channel_types[i - 1].name);

  }

  static DEVICE_ATTR_RO(typename);

  
  static struct attribute *channel_attrs[] = {

  	&dev_attr_physaddr.attr,
  	&dev_attr_nbytes.attr,
  	&dev_attr_clientpartition.attr,
  	&dev_attr_typeguid.attr,
  	&dev_attr_zoneguid.attr,
  	&dev_attr_typename.attr,
  	NULL

  };

  ATTRIBUTE_GROUPS(channel);

  /*
   *  BUS instance attributes

   *
   *  define & implement display of bus attributes under

   *  /sys/bus/visorbus/devices/visorbus<n>.

   */

  static ssize_t partition_handle_show(struct device *dev,

  				     struct device_attribute *attr, char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);
  	u64 handle = visorchannel_get_clientpartition(vdev->visorchannel);

  	return sprintf(buf, "0x%llx
  ", handle);

  }

  static DEVICE_ATTR_RO(partition_handle);

  static ssize_t partition_guid_show(struct device *dev,

  				   struct device_attribute *attr, char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);

  	return sprintf(buf, "{%pUb}
  ", &vdev->partition_guid);

  }

  static DEVICE_ATTR_RO(partition_guid);

  static ssize_t partition_name_show(struct device *dev,

  				   struct device_attribute *attr, char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);

  	return sprintf(buf, "%s
  ", vdev->name);

  }

  static DEVICE_ATTR_RO(partition_name);

  static ssize_t channel_addr_show(struct device *dev,

  				 struct device_attribute *attr, char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);
  	u64 addr = visorchannel_get_physaddr(vdev->visorchannel);

  	return sprintf(buf, "0x%llx
  ", addr);

  }

  static DEVICE_ATTR_RO(channel_addr);

  static ssize_t channel_bytes_show(struct device *dev,

  				  struct device_attribute *attr, char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);
  	u64 nbytes = visorchannel_get_nbytes(vdev->visorchannel);

  	return sprintf(buf, "0x%llx
  ", nbytes);

  }

  static DEVICE_ATTR_RO(channel_bytes);

  static ssize_t channel_id_show(struct device *dev,

  			       struct device_attribute *attr, char *buf)

  {

  	struct visor_device *vdev = to_visor_device(dev);

  	int len = 0;

  	visorchannel_id(vdev->visorchannel, buf);
  	len = strlen(buf);
  	buf[len++] = '
  ';

  	return len;
  }

  static DEVICE_ATTR_RO(channel_id);

  static struct attribute *visorbus_attrs[] = {

  	&dev_attr_partition_handle.attr,
  	&dev_attr_partition_guid.attr,
  	&dev_attr_partition_name.attr,
  	&dev_attr_channel_addr.attr,
  	&dev_attr_channel_bytes.attr,
  	&dev_attr_channel_id.attr,
  	NULL

  };

  ATTRIBUTE_GROUPS(visorbus);

  /*
   *  BUS debugfs entries
   *
   *  define & implement display of debugfs attributes under
   *  /sys/kernel/debug/visorbus/visorbus<n>.
   */

  /*

   * vbuschannel_print_devinfo() - format a struct visor_vbus_deviceinfo

   *                               and write it to a seq_file

   * @devinfo: the struct visor_vbus_deviceinfo to format

   * @seq: seq_file to write to
   * @devix: the device index to be included in the output data, or -1 if no
   *         device index is to be included
   *
   * Reads @devInfo, and writes it in human-readable notation to @seq.
   */

  static void vbuschannel_print_devinfo(struct visor_vbus_deviceinfo *devinfo,
  				      struct seq_file *seq, int devix)

  {

  	/* uninitialized vbus device entry */

  	if (!isprint(devinfo->devtype[0]))

  		return;

  	if (devix >= 0)
  		seq_printf(seq, "[%d]", devix);
  	else
  		/* vbus device entry is for bus or chipset */
  		seq_puts(seq, "   ");

  	/*
  	 * Note: because the s-Par back-end is free to scribble in this area,
  	 * we never assume '\0'-termination.
  	 */
  	seq_printf(seq, "%-*.*s ", (int)sizeof(devinfo->devtype),
  		   (int)sizeof(devinfo->devtype), devinfo->devtype);
  	seq_printf(seq, "%-*.*s ", (int)sizeof(devinfo->drvname),
  		   (int)sizeof(devinfo->drvname), devinfo->drvname);
  	seq_printf(seq, "%.*s
  ", (int)sizeof(devinfo->infostrs),
  		   devinfo->infostrs);
  }

  static int bus_info_debugfs_show(struct seq_file *seq, void *v)

  {

  	int i = 0;

  	unsigned long off;

  	struct visor_vbus_deviceinfo dev_info;

  	struct visor_device *vdev = seq->private;
  	struct visorchannel *channel = vdev->visorchannel;

  
  	if (!channel)
  		return 0;
  
  	seq_printf(seq,

  		   "Client device/driver info for %s partition (vbus #%u):
  ",

  		   ((vdev->name) ? (char *)(vdev->name) : ""),
  		   vdev->chipset_bus_no);
  	if (visorchannel_read(channel,

  			      offsetof(struct visor_vbus_channel, chp_info),

  			      &dev_info, sizeof(dev_info)) >= 0)
  		vbuschannel_print_devinfo(&dev_info, seq, -1);
  	if (visorchannel_read(channel,

  			      offsetof(struct visor_vbus_channel, bus_info),

  			      &dev_info, sizeof(dev_info)) >= 0)
  		vbuschannel_print_devinfo(&dev_info, seq, -1);

  	off = offsetof(struct visor_vbus_channel, dev_info);

  	while (off + sizeof(dev_info) <= visorchannel_get_nbytes(channel)) {
  		if (visorchannel_read(channel, off, &dev_info,
  				      sizeof(dev_info)) >= 0)
  			vbuschannel_print_devinfo(&dev_info, seq, i);
  		off += sizeof(dev_info);
  		i++;
  	}

  	return 0;
  }

  static int bus_info_debugfs_open(struct inode *inode, struct file *file)

  {

  	return single_open(file, bus_info_debugfs_show, inode->i_private);

  }

  static const struct file_operations bus_info_debugfs_fops = {

  	.owner = THIS_MODULE,

  	.open = bus_info_debugfs_open,

  	.read = seq_read,
  	.llseek = seq_lseek,
  	.release = single_release,
  };

  static void dev_periodic_work(struct timer_list *t)

  {

  	struct visor_device *dev = from_timer(dev, t, timer);

  	struct visor_driver *drv = to_visor_driver(dev->device.driver);

  	drv->channel_interrupt(dev);

  	mod_timer(&dev->timer, jiffies + POLLJIFFIES_NORMALCHANNEL);

  }

  static int dev_start_periodic_work(struct visor_device *dev)

  {

  	if (dev->being_removed || dev->timer_active)

  		return -EINVAL;

  	/* now up by at least 2 */
  	get_device(&dev->device);

  	dev->timer.expires = jiffies + POLLJIFFIES_NORMALCHANNEL;
  	add_timer(&dev->timer);
  	dev->timer_active = true;

  	return 0;

  }

  static void dev_stop_periodic_work(struct visor_device *dev)

  {

  	if (!dev->timer_active)
  		return;

  	del_timer_sync(&dev->timer);
  	dev->timer_active = false;
  	put_device(&dev->device);

  }

  /*

   * visordriver_remove_device() - handle visor device going away
   * @xdev: struct device for the visor device being removed
   *
   * This is called when device_unregister() is called for each child device
   * instance, to notify the appropriate visorbus function driver that the device
   * is going away, and to decrease the reference count of the device.
   *
   * Return: 0 iff successful

   */

  static int visordriver_remove_device(struct device *xdev)

  {

  	struct visor_device *dev = to_visor_device(xdev);
  	struct visor_driver *drv = to_visor_driver(xdev->driver);

  	mutex_lock(&dev->visordriver_callback_lock);

  	dev->being_removed = true;

  	drv->remove(dev);

  	mutex_unlock(&dev->visordriver_callback_lock);

  	dev_stop_periodic_work(dev);

  	put_device(&dev->device);

  	return 0;

  }

  /*

   * visorbus_unregister_visor_driver() - unregisters the provided driver
   * @drv: the driver to unregister
   *
   * A visor function driver calls this function to unregister the driver,
   * i.e., within its module_exit function.

   */

  void visorbus_unregister_visor_driver(struct visor_driver *drv)

  {

  	driver_unregister(&drv->driver);
  }
  EXPORT_SYMBOL_GPL(visorbus_unregister_visor_driver);

  /*

   * visorbus_read_channel() - reads from the designated channel into
   *                           the provided buffer
   * @dev:    the device whose channel is read from
   * @offset: the offset into the channel at which reading starts
   * @dest:   the destination buffer that is written into from the channel
   * @nbytes: the number of bytes to read from the channel
   *

   * If receiving a message, use the visorchannel_signalremove() function instead.

   *
   * Return: integer indicating success (zero) or failure (non-zero)
   */

  int visorbus_read_channel(struct visor_device *dev, unsigned long offset,
  			  void *dest, unsigned long nbytes)

  {
  	return visorchannel_read(dev->visorchannel, offset, dest, nbytes);
  }
  EXPORT_SYMBOL_GPL(visorbus_read_channel);

  /*

   * visorbus_write_channel() - writes the provided buffer into the designated
   *                            channel
   * @dev:    the device whose channel is written to
   * @offset: the offset into the channel at which writing starts
   * @src:    the source buffer that is written into the channel
   * @nbytes: the number of bytes to write into the channel
   *

   * If sending a message, use the visorchannel_signalinsert() function instead.

   *
   * Return: integer indicating success (zero) or failure (non-zero)
   */

  int visorbus_write_channel(struct visor_device *dev, unsigned long offset,
  			   void *src, unsigned long nbytes)

  {
  	return visorchannel_write(dev->visorchannel, offset, src, nbytes);
  }
  EXPORT_SYMBOL_GPL(visorbus_write_channel);

  /*

   * visorbus_enable_channel_interrupts() - enables interrupts on the
   *                                        designated device
   * @dev: the device on which to enable interrupts
   *
   * Currently we don't yet have a real interrupt, so for now we just call the
   * interrupt function periodically via a timer.

   */

  int visorbus_enable_channel_interrupts(struct visor_device *dev)

  {

  	struct visor_driver *drv = to_visor_driver(dev->device.driver);
  
  	if (!drv->channel_interrupt) {
  		dev_err(&dev->device, "%s no interrupt function!
  ", __func__);

  		return -ENOENT;

  	}

  	return dev_start_periodic_work(dev);

  }
  EXPORT_SYMBOL_GPL(visorbus_enable_channel_interrupts);

  /*

   * visorbus_disable_channel_interrupts() - disables interrupts on the
   *                                         designated device
   * @dev: the device on which to disable interrupts
   */

  void visorbus_disable_channel_interrupts(struct visor_device *dev)

  {
  	dev_stop_periodic_work(dev);
  }
  EXPORT_SYMBOL_GPL(visorbus_disable_channel_interrupts);

  /*

   * create_visor_device() - create visor device as a result of receiving the
   *                         controlvm device_create message for a new device
   * @dev: a freshly-zeroed struct visor_device, containing only filled-in values
   *       for chipset_bus_no and chipset_dev_no, that will be initialized
   *
   * This is how everything starts from the device end.
   * This function is called when a channel first appears via a ControlVM

   * message.  In response, this function allocates a visor_device to correspond
   * to the new channel, and attempts to connect it the appropriate * driver. If
   * the appropriate driver is found, the visor_driver.probe() function for that
   * driver will be called, and will be passed the new * visor_device that we
   * just created.

   *

   * It's ok if the appropriate driver is not yet loaded, because in that case
   * the new device struct will just stick around in the bus' list of devices.
   * When the appropriate driver calls visorbus_register_visor_driver(), the

   * visor_driver.probe() for the new driver will be called with the new device.

   *
   * Return: 0 if successful, otherwise the negative value returned by
   *         device_add() indicating the reason for failure

   */

  int create_visor_device(struct visor_device *dev)

  {

  	int err;

  	u32 chipset_bus_no = dev->chipset_bus_no;
  	u32 chipset_dev_no = dev->chipset_dev_no;

  	mutex_init(&dev->visordriver_callback_lock);

  	dev->device.bus = &visorbus_type;

  	dev->device.groups = channel_groups;

  	device_initialize(&dev->device);
  	dev->device.release = visorbus_release_device;
  	/* keep a reference just for us (now 2) */
  	get_device(&dev->device);

  	timer_setup(&dev->timer, dev_periodic_work, 0);

  	/*

  	 * bus_id must be a unique name with respect to this bus TYPE (NOT bus
  	 * instance).  That's why we need to include the bus number within the
  	 * name.

  	 */

  	err = dev_set_name(&dev->device, "vbus%u:dev%u",
  			   chipset_bus_no, chipset_dev_no);
  	if (err)
  		goto err_put;

  	/*
  	 * device_add does this:

  	 *    bus_add_device(dev)
  	 *    ->device_attach(dev)
  	 *      ->for each driver drv registered on the bus that dev is on
  	 *          if (dev.drv)  **  device already has a driver **
  	 *            ** not sure we could ever get here... **
  	 *          else
  	 *            if (bus.match(dev,drv)) [visorbus_match]
  	 *              dev.drv = drv
  	 *              if (!drv.probe(dev))  [visordriver_probe_device]
  	 *                dev.drv = NULL
  	 *

  	 * Note that device_add does NOT fail if no driver failed to claim the
  	 * device.  The device will be linked onto bus_type.klist_devices
  	 * regardless (use bus_for_each_dev).

  	 */

  	err = device_add(&dev->device);

  	if (err < 0)

  		goto err_put;

  	list_add_tail(&dev->list_all, &list_all_device_instances);

  	dev->state.created = 1;
  	visorbus_response(dev, err, CONTROLVM_DEVICE_CREATE);

  	/* success: reference kept via unmatched get_device() */
  	return 0;

  err_put:

  	put_device(&dev->device);

  	dev_err(&dev->device, "Creating visor device failed. %d
  ", err);

  	return err;

  }

  void remove_visor_device(struct visor_device *dev)

  {
  	list_del(&dev->list_all);

  	put_device(&dev->device);

  	if (dev->pending_msg_hdr)
  		visorbus_response(dev, 0, CONTROLVM_DEVICE_DESTROY);

  	device_unregister(&dev->device);
  }

  static int get_vbus_header_info(struct visorchannel *chan,

  				struct device *dev,

  				struct visor_vbus_headerinfo *hdr_info)

  {

  	int err;

  	if (!visor_check_channel(visorchannel_get_header(chan),

  				 dev,

  				 &visor_vbus_channel_guid,

  				 "vbus",
  				 sizeof(struct visor_vbus_channel),
  				 VISOR_VBUS_CHANNEL_VERSIONID,

  				 VISOR_CHANNEL_SIGNATURE))

  		return -EINVAL;

  	err = visorchannel_read(chan, sizeof(struct channel_header), hdr_info,
  				sizeof(*hdr_info));
  	if (err < 0)
  		return err;

  	if (hdr_info->struct_bytes < sizeof(struct visor_vbus_headerinfo))

  		return -EINVAL;

  	if (hdr_info->device_info_struct_bytes <

  	    sizeof(struct visor_vbus_deviceinfo))

  		return -EINVAL;

  	return 0;

  }

  /*

   * write_vbus_chp_info() - write the contents of <info> to the struct

   *                         visor_vbus_channel.chp_info

   * @chan:     indentifies the s-Par channel that will be updated
   * @hdr_info: used to find appropriate channel offset to write data
   * @info:     contains the information to write
   *
   * Writes chipset info into the channel memory to be used for diagnostic
   * purposes.

   *

   * Returns no value since this is debug information and not needed for

   * device functionality.

   */

  static void write_vbus_chp_info(struct visorchannel *chan,
  				struct visor_vbus_headerinfo *hdr_info,
  				struct visor_vbus_deviceinfo *info)

  {

  	int off;

  
  	if (hdr_info->chp_info_offset == 0)

  		return;

  	off = sizeof(struct channel_header) + hdr_info->chp_info_offset;

  	visorchannel_write(chan, off, info, sizeof(*info));

  }

  /*

   * write_vbus_bus_info() - write the contents of <info> to the struct

   *                         visor_vbus_channel.bus_info

   * @chan:     indentifies the s-Par channel that will be updated
   * @hdr_info: used to find appropriate channel offset to write data
   * @info:     contains the information to write
   *
   * Writes bus info into the channel memory to be used for diagnostic
   * purposes.

   *

   * Returns no value since this is debug information and not needed for

   * device functionality.

   */

  static void write_vbus_bus_info(struct visorchannel *chan,
  				struct visor_vbus_headerinfo *hdr_info,
  				struct visor_vbus_deviceinfo *info)

  {

  	int off;

  
  	if (hdr_info->bus_info_offset == 0)

  		return;

  	off = sizeof(struct channel_header) + hdr_info->bus_info_offset;

  	visorchannel_write(chan, off, info, sizeof(*info));

  }

  /*

   * write_vbus_dev_info() - write the contents of <info> to the struct

   *                         visor_vbus_channel.dev_info[<devix>]

   * @chan:     indentifies the s-Par channel that will be updated
   * @hdr_info: used to find appropriate channel offset to write data
   * @info:     contains the information to write
   * @devix:    the relative device number (0..n-1) of the device on the bus

   *

   * Writes device info into the channel memory to be used for diagnostic
   * purposes.
   *
   * Returns no value since this is debug information and not needed for

   * device functionality.

   */

  static void write_vbus_dev_info(struct visorchannel *chan,
  				struct visor_vbus_headerinfo *hdr_info,
  				struct visor_vbus_deviceinfo *info,
  				unsigned int devix)

  {

  	int off;

  
  	if (hdr_info->dev_info_offset == 0)

  		return;

  	off = (sizeof(struct channel_header) + hdr_info->dev_info_offset) +
  	      (hdr_info->device_info_struct_bytes * devix);

  	visorchannel_write(chan, off, info, sizeof(*info));

  }

  static void bus_device_info_init(

  		struct visor_vbus_deviceinfo *bus_device_info_ptr,

  		const char *dev_type, const char *drv_name)
  {

  	memset(bus_device_info_ptr, 0, sizeof(struct visor_vbus_deviceinfo));

  	snprintf(bus_device_info_ptr->devtype,
  		 sizeof(bus_device_info_ptr->devtype),
  		 "%s", (dev_type) ? dev_type : "unknownType");
  	snprintf(bus_device_info_ptr->drvname,
  		 sizeof(bus_device_info_ptr->drvname),
  		 "%s", (drv_name) ? drv_name : "unknownDriver");
  	snprintf(bus_device_info_ptr->infostrs,
  		 sizeof(bus_device_info_ptr->infostrs), "kernel ver. %s",
  		 utsname()->release);
  }

  /*

   * publish_vbus_dev_info() - for a child device just created on a client bus,
   *			     fill in information about the driver that is
   *			     controlling this device into the appropriate slot
   *			     within the vbus channel of the bus instance

   * @visordev: struct visor_device for the desired device

   */

  static void publish_vbus_dev_info(struct visor_device *visordev)

  {
  	int i;

  	struct visor_device *bdev;

  	struct visor_driver *visordrv;

  	u32 bus_no = visordev->chipset_bus_no;
  	u32 dev_no = visordev->chipset_dev_no;

  	struct visor_vbus_deviceinfo dev_info;

  	const char *chan_type_name = NULL;

  	struct visor_vbus_headerinfo *hdr_info;

  
  	if (!visordev->device.driver)

  		return;

  	bdev = visorbus_get_device_by_id(bus_no, BUS_ROOT_DEVICE, NULL);
  	if (!bdev)
  		return;

  	hdr_info = (struct visor_vbus_headerinfo *)bdev->vbus_hdr_info;

  	if (!hdr_info)
  		return;

  	visordrv = to_visor_driver(visordev->device.driver);

  	/*
  	 * Within the list of device types (by GUID) that the driver

  	 * says it supports, find out which one of those types matches
  	 * the type of this device, so that we can include the device
  	 * type name
  	 */
  	for (i = 0; visordrv->channel_types[i].name; i++) {

  		if (guid_equal(&visordrv->channel_types[i].guid,
  			       &visordev->channel_type_guid)) {

  			chan_type_name = visordrv->channel_types[i].name;
  			break;
  		}
  	}

  	bus_device_info_init(&dev_info, chan_type_name, visordrv->name);

  	write_vbus_dev_info(bdev->visorchannel, hdr_info, &dev_info, dev_no);

  	write_vbus_chp_info(bdev->visorchannel, hdr_info, &chipset_driverinfo);
  	write_vbus_bus_info(bdev->visorchannel, hdr_info,
  			    &clientbus_driverinfo);

  }

  /*

   * visordriver_probe_device() - handle new visor device coming online
   * @xdev: struct device for the visor device being probed
   *
   * This is called automatically upon adding a visor_device (device_add), or
   * adding a visor_driver (visorbus_register_visor_driver), but only after
   * visorbus_match() has returned 1 to indicate a successful match between
   * driver and device.
   *
   * If successful, a reference to the device will be held onto via get_device().
   *
   * Return: 0 if successful, meaning the function driver's probe() function
   *         was successful with this device, otherwise a negative errno
   *         value indicating failure reason
   */

  static int visordriver_probe_device(struct device *xdev)

  {

  	int err;

  	struct visor_driver *drv = to_visor_driver(xdev->driver);
  	struct visor_device *dev = to_visor_device(xdev);

  
  	mutex_lock(&dev->visordriver_callback_lock);
  	dev->being_removed = false;

  	err = drv->probe(dev);
  	if (err) {
  		mutex_unlock(&dev->visordriver_callback_lock);
  		return err;

  	}

  	/* success: reference kept via unmatched get_device() */
  	get_device(&dev->device);
  	publish_vbus_dev_info(dev);

  	mutex_unlock(&dev->visordriver_callback_lock);

  	return 0;

  }

  /*

   * visorbus_register_visor_driver() - registers the provided visor driver for
   *				      handling one or more visor device

   *                                    types (channel_types)
   * @drv: the driver to register
   *

   * A visor function driver calls this function to register the driver. The
   * caller MUST fill in the following fields within the #drv structure:

   *     name, version, owner, channel_types, probe, remove
   *
   * Here's how the whole Linux bus / driver / device model works.
   *
   * At system start-up, the visorbus kernel module is loaded, which registers
   * visorbus_type as a bus type, using bus_register().
   *
   * All kernel modules that support particular device types on a
   * visorbus bus are loaded.  Each of these kernel modules calls
   * visorbus_register_visor_driver() in their init functions, passing a
   * visor_driver struct.  visorbus_register_visor_driver() in turn calls
   * register_driver(&visor_driver.driver).  This .driver member is
   * initialized with generic methods (like probe), whose sole responsibility
   * is to act as a broker for the real methods, which are within the
   * visor_driver struct.  (This is the way the subclass behavior is
   * implemented, since visor_driver is essentially a subclass of the
   * generic driver.)  Whenever a driver_register() happens, core bus code in
   * the kernel does (see device_attach() in drivers/base/dd.c):
   *
   *     for each dev associated with the bus (the bus that driver is on) that
   *     does not yet have a driver
   *         if bus.match(dev,newdriver) == yes_matched  ** .match specified
   *                                                ** during bus_register().
   *             newdriver.probe(dev)  ** for visor drivers, this will call
   *                   ** the generic driver.probe implemented in visorbus.c,
   *                   ** which in turn calls the probe specified within the
   *                   ** struct visor_driver (which was specified by the
   *                   ** actual device driver as part of
   *                   ** visorbus_register_visor_driver()).
   *
   * The above dance also happens when a new device appears.
   * So the question is, how are devices created within the system?
   * Basically, just call device_add(dev).  See pci_bus_add_devices().
   * pci_scan_device() shows an example of how to build a device struct.  It
   * returns the newly-created struct to pci_scan_single_device(), who adds it
   * to the list of devices at PCIBUS.devices.  That list of devices is what
   * is traversed by pci_bus_add_devices().
   *
   * Return: integer indicating success (zero) or failure (non-zero)
   */
  int visorbus_register_visor_driver(struct visor_driver *drv)
  {

  	/* can't register on a nonexistent bus */

  	if (!initialized)

  		return -ENODEV;

  	if (!drv->probe)

  		return -EINVAL;

  	if (!drv->remove)

  		return -EINVAL;

  	if (!drv->pause)

  		return -EINVAL;

  	if (!drv->resume)

  		return -EINVAL;

  	drv->driver.name = drv->name;
  	drv->driver.bus = &visorbus_type;
  	drv->driver.probe = visordriver_probe_device;
  	drv->driver.remove = visordriver_remove_device;
  	drv->driver.owner = drv->owner;

  	/*
  	 * driver_register does this:
  	 *   bus_add_driver(drv)
  	 *   ->if (drv.bus)  ** (bus_type) **
  	 *       driver_attach(drv)
  	 *         for each dev with bus type of drv.bus
  	 *           if (!dev.drv)  ** no driver assigned yet **
  	 *             if (bus.match(dev,drv))  [visorbus_match]
  	 *               dev.drv = drv
  	 *               if (!drv.probe(dev))   [visordriver_probe_device]
  	 *                 dev.drv = NULL
  	 */

  	return driver_register(&drv->driver);

  }
  EXPORT_SYMBOL_GPL(visorbus_register_visor_driver);

  /*

   * visorbus_create_instance() - create a device instance for the visorbus itself

   * @dev: struct visor_device indicating the bus instance
   *
   * Return: 0 for success, otherwise negative errno value indicating reason for
   *         failure

   */

  int visorbus_create_instance(struct visor_device *dev)

  {

  	int id = dev->chipset_bus_no;

  	int err;

  	struct visor_vbus_headerinfo *hdr_info;

  	hdr_info = kzalloc(sizeof(*hdr_info), GFP_KERNEL);

  	if (!hdr_info)
  		return -ENOMEM;

  	dev_set_name(&dev->device, "visorbus%d", id);
  	dev->device.bus = &visorbus_type;
  	dev->device.groups = visorbus_groups;
  	dev->device.release = visorbus_release_busdevice;

  	dev->debugfs_dir = debugfs_create_dir(dev_name(&dev->device),
  					      visorbus_debugfs_dir);

  	dev->debugfs_bus_info = debugfs_create_file("client_bus_info", 0440,
  						    dev->debugfs_dir, dev,
  						    &bus_info_debugfs_fops);

  	dev_set_drvdata(&dev->device, dev);

  	err = get_vbus_header_info(dev->visorchannel, &dev->device, hdr_info);

  	if (err < 0)

  		goto err_debugfs_dir;

  	err = device_register(&dev->device);

  	if (err < 0)

  		goto err_debugfs_dir;

  	list_add_tail(&dev->list_all, &list_all_bus_instances);

  	dev->state.created = 1;

  	dev->vbus_hdr_info = (void *)hdr_info;

  	write_vbus_chp_info(dev->visorchannel, hdr_info, &chipset_driverinfo);
  	write_vbus_bus_info(dev->visorchannel, hdr_info, &clientbus_driverinfo);

  	visorbus_response(dev, err, CONTROLVM_BUS_CREATE);

  	return 0;

  
  err_debugfs_dir:
  	debugfs_remove_recursive(dev->debugfs_dir);

  	kfree(hdr_info);

  	dev_err(&dev->device, "%s failed: %d
  ", __func__, err);

  	return err;

  }

  /*

   * visorbus_remove_instance() - remove a device instance for the visorbus itself

   * @dev: struct visor_device indentifying the bus to remove

   */

  void visorbus_remove_instance(struct visor_device *dev)

  {

  	/*
  	 * Note that this will result in the release method for

  	 * dev->dev being called, which will call

  	 * visorbus_release_busdevice().  This has something to do with
  	 * the put_device() done in device_unregister(), but I have never
  	 * successfully been able to trace thru the code to see where/how
  	 * release() gets called.  But I know it does.
  	 */

  	kfree(dev->vbus_hdr_info);
  	list_del(&dev->list_all);

  	if (dev->pending_msg_hdr)
  		visorbus_response(dev, 0, CONTROLVM_BUS_DESTROY);

  	device_unregister(&dev->device);

  }

  /*

   * remove_all_visor_devices() - remove all child visorbus device instances

   */

  static void remove_all_visor_devices(void)

  {
  	struct list_head *listentry, *listtmp;
  
  	list_for_each_safe(listentry, listtmp, &list_all_device_instances) {

  		struct visor_device *dev;
  
  		dev = list_entry(listentry, struct visor_device, list_all);

  		remove_visor_device(dev);
  	}
  }

  /*

   * pause_state_change_complete() - the callback function to be called by a
   *                                 visorbus function driver when a
   *                                 pending "pause device" operation has
   *                                 completed
   * @dev: struct visor_device identifying the paused device
   * @status: 0 iff the pause state change completed successfully, otherwise
   *          a negative errno value indicating the reason for failure

   */

  static void pause_state_change_complete(struct visor_device *dev, int status)

  {
  	if (!dev->pausing)

  		return;

  	dev->pausing = false;

  	visorbus_device_changestate_response(dev, status,
  					     segment_state_standby);

  }

  /*

   * resume_state_change_complete() - the callback function to be called by a
   *                                  visorbus function driver when a
   *                                  pending "resume device" operation has
   *                                  completed
   * @dev: struct visor_device identifying the resumed device
   * @status: 0 iff the resume state change completed successfully, otherwise
   *          a negative errno value indicating the reason for failure

   */

  static void resume_state_change_complete(struct visor_device *dev, int status)

  {
  	if (!dev->resuming)

  		return;

  	dev->resuming = false;

  	/*
  	 * Notify the chipset driver that the resume is complete,

  	 * which will presumably want to send some sort of response to

  	 * the initiator.
  	 */

  	visorbus_device_changestate_response(dev, status,
  					     segment_state_running);

  }

  /*

   * visorchipset_initiate_device_pause_resume() - start a pause or resume
   *                                               operation for a visor device

   * @dev: struct visor_device identifying the device being paused or resumed
   * @is_pause: true to indicate pause operation, false to indicate resume
   *
   * Tell the subordinate function driver for a specific device to pause
   * or resume that device.  Success/failure result is returned asynchronously
   * via a callback function; see pause_state_change_complete() and
   * resume_state_change_complete().

   */

  static int visorchipset_initiate_device_pause_resume(struct visor_device *dev,
  						     bool is_pause)

  {

  	int err;

  	struct visor_driver *drv;

  	/* If no driver associated with the device nothing to pause/resume */
  	if (!dev->device.driver)
  		return 0;

  	if (dev->pausing || dev->resuming)
  		return -EBUSY;

  	drv = to_visor_driver(dev->device.driver);

  	if (is_pause) {

  		dev->pausing = true;

  		err = drv->pause(dev, pause_state_change_complete);

  	} else {

  		/*
  		 * The vbus_dev_info structure in the channel was been cleared,
  		 * make sure it is valid.

  		 */

  		publish_vbus_dev_info(dev);

  		dev->resuming = true;

  		err = drv->resume(dev, resume_state_change_complete);

  	}

  	return err;

  }

  /*

   * visorchipset_device_pause() - start a pause operation for a visor device

   * @dev_info: struct visor_device identifying the device being paused
   *
   * Tell the subordinate function driver for a specific device to pause
   * that device.  Success/failure result is returned asynchronously
   * via a callback function; see pause_state_change_complete().
   */

  int visorchipset_device_pause(struct visor_device *dev_info)

  {

  	int err;

  	err = visorchipset_initiate_device_pause_resume(dev_info, true);

  	if (err < 0) {
  		dev_info->pausing = false;

  		return err;

  	}

  	return 0;

  }

  /*

   * visorchipset_device_resume() - start a resume operation for a visor device

   * @dev_info: struct visor_device identifying the device being resumed
   *
   * Tell the subordinate function driver for a specific device to resume
   * that device.  Success/failure result is returned asynchronously
   * via a callback function; see resume_state_change_complete().
   */

  int visorchipset_device_resume(struct visor_device *dev_info)

  {

  	int err;

  	err = visorchipset_initiate_device_pause_resume(dev_info, false);

  	if (err < 0) {

  		dev_info->resuming = false;

  		return err;

  	}

  	return 0;

  }

  int visorbus_init(void)

  {

  	int err;

  	visorbus_debugfs_dir = debugfs_create_dir("visorbus", NULL);

  	bus_device_info_init(&clientbus_driverinfo, "clientbus", "visorbus");

  	err = bus_register(&visorbus_type);

  	if (err < 0)
  		return err;

  	initialized = true;

  	bus_device_info_init(&chipset_driverinfo, "chipset", "visorchipset");

  	return 0;

  }

  void visorbus_exit(void)

  {
  	struct list_head *listentry, *listtmp;

  	remove_all_visor_devices();

  	list_for_each_safe(listentry, listtmp, &list_all_bus_instances) {

  		struct visor_device *dev;
  
  		dev = list_entry(listentry, struct visor_device, list_all);