/*
   * Enclosure Services
   *
   * Copyright (C) 2008 James Bottomley <James.Bottomley@HansenPartnership.com>
   *
  **-----------------------------------------------------------------------------
  **
  **  This program is free software; you can redistribute it and/or
  **  modify it under the terms of the GNU General Public License
  **  version 2 as published by the Free Software Foundation.
  **
  **  This program is distributed in the hope that it will be useful,
  **  but WITHOUT ANY WARRANTY; without even the implied warranty of
  **  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  **  GNU General Public License for more details.
  **
  **  You should have received a copy of the GNU General Public License
  **  along with this program; if not, write to the Free Software
  **  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  **
  **-----------------------------------------------------------------------------
  */
  #include <linux/device.h>
  #include <linux/enclosure.h>
  #include <linux/err.h>
  #include <linux/list.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/slab.h>
  
  static LIST_HEAD(container_list);
  static DEFINE_MUTEX(container_list_lock);
  static struct class enclosure_class;
  
  /**
   * enclosure_find - find an enclosure given a parent device
   * @dev:	the parent to match against
   * @start:	Optional enclosure device to start from (NULL if none)
   *
   * Looks through the list of registered enclosures to find all those
   * with @dev as a parent.  Returns NULL if no enclosure is
   * found. @start can be used as a starting point to obtain multiple
   * enclosures per parent (should begin with NULL and then be set to
   * each returned enclosure device). Obtains a reference to the
   * enclosure class device which must be released with device_put().
   * If @start is not NULL, a reference must be taken on it which is
   * released before returning (this allows a loop through all
   * enclosures to exit with only the reference on the enclosure of
   * interest held).  Note that the @dev may correspond to the actual
   * device housing the enclosure, in which case no iteration via @start
   * is required.
   */
  struct enclosure_device *enclosure_find(struct device *dev,
  					struct enclosure_device *start)
  {
  	struct enclosure_device *edev;
  
  	mutex_lock(&container_list_lock);
  	edev = list_prepare_entry(start, &container_list, node);
  	if (start)
  		put_device(&start->edev);
  
  	list_for_each_entry_continue(edev, &container_list, node) {
  		struct device *parent = edev->edev.parent;
  		/* parent might not be immediate, so iterate up to
  		 * the root of the tree if necessary */
  		while (parent) {
  			if (parent == dev) {
  				get_device(&edev->edev);
  				mutex_unlock(&container_list_lock);
  				return edev;
  			}
  			parent = parent->parent;
  		}
  	}
  	mutex_unlock(&container_list_lock);
  
  	return NULL;
  }
  EXPORT_SYMBOL_GPL(enclosure_find);
  
  /**
   * enclosure_for_each_device - calls a function for each enclosure
   * @fn:		the function to call
   * @data:	the data to pass to each call
   *
   * Loops over all the enclosures calling the function.
   *
   * Note, this function uses a mutex which will be held across calls to
   * @fn, so it must have non atomic context, and @fn may (although it
   * should not) sleep or otherwise cause the mutex to be held for
   * indefinite periods
   */
  int enclosure_for_each_device(int (*fn)(struct enclosure_device *, void *),
  			      void *data)
  {
  	int error = 0;
  	struct enclosure_device *edev;
  
  	mutex_lock(&container_list_lock);
  	list_for_each_entry(edev, &container_list, node) {
  		error = fn(edev, data);
  		if (error)
  			break;
  	}
  	mutex_unlock(&container_list_lock);
  
  	return error;
  }
  EXPORT_SYMBOL_GPL(enclosure_for_each_device);
  
  /**
   * enclosure_register - register device as an enclosure
   *
   * @dev:	device containing the enclosure
   * @components:	number of components in the enclosure
   *
   * This sets up the device for being an enclosure.  Note that @dev does
   * not have to be a dedicated enclosure device.  It may be some other type
   * of device that additionally responds to enclosure services
   */
  struct enclosure_device *
  enclosure_register(struct device *dev, const char *name, int components,
  		   struct enclosure_component_callbacks *cb)
  {
  	struct enclosure_device *edev =
  		kzalloc(sizeof(struct enclosure_device) +
  			sizeof(struct enclosure_component)*components,
  			GFP_KERNEL);
  	int err, i;
  
  	BUG_ON(!cb);
  
  	if (!edev)
  		return ERR_PTR(-ENOMEM);
  
  	edev->components = components;
  
  	edev->edev.class = &enclosure_class;
  	edev->edev.parent = get_device(dev);
  	edev->cb = cb;
  	dev_set_name(&edev->edev, "%s", name);
  	err = device_register(&edev->edev);
  	if (err)
  		goto err;
  
  	for (i = 0; i < components; i++)
  		edev->component[i].number = -1;
  
  	mutex_lock(&container_list_lock);
  	list_add_tail(&edev->node, &container_list);
  	mutex_unlock(&container_list_lock);
  
  	return edev;
  
   err:
  	put_device(edev->edev.parent);
  	kfree(edev);
  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL_GPL(enclosure_register);
  
  static struct enclosure_component_callbacks enclosure_null_callbacks;
  
  /**
   * enclosure_unregister - remove an enclosure
   *
   * @edev:	the registered enclosure to remove;
   */
  void enclosure_unregister(struct enclosure_device *edev)
  {
  	int i;
  
  	mutex_lock(&container_list_lock);
  	list_del(&edev->node);
  	mutex_unlock(&container_list_lock);
  
  	for (i = 0; i < edev->components; i++)
  		if (edev->component[i].number != -1)
  			device_unregister(&edev->component[i].cdev);
  
  	/* prevent any callbacks into service user */
  	edev->cb = &enclosure_null_callbacks;
  	device_unregister(&edev->edev);
  }
  EXPORT_SYMBOL_GPL(enclosure_unregister);
  
  #define ENCLOSURE_NAME_SIZE	64
  
  static void enclosure_link_name(struct enclosure_component *cdev, char *name)
  {
  	strcpy(name, "enclosure_device:");
  	strcat(name, dev_name(&cdev->cdev));
  }
  
  static void enclosure_remove_links(struct enclosure_component *cdev)
  {
  	char name[ENCLOSURE_NAME_SIZE];
  
  	/*
  	 * In odd circumstances, like multipath devices, something else may
  	 * already have removed the links, so check for this condition first.
  	 */
  	if (!cdev->dev->kobj.sd)
  		return;
  
  	enclosure_link_name(cdev, name);
  	sysfs_remove_link(&cdev->dev->kobj, name);
  	sysfs_remove_link(&cdev->cdev.kobj, "device");
  }
  
  static int enclosure_add_links(struct enclosure_component *cdev)
  {
  	int error;
  	char name[ENCLOSURE_NAME_SIZE];
  
  	error = sysfs_create_link(&cdev->cdev.kobj, &cdev->dev->kobj, "device");
  	if (error)
  		return error;
  
  	enclosure_link_name(cdev, name);
  	error = sysfs_create_link(&cdev->dev->kobj, &cdev->cdev.kobj, name);
  	if (error)
  		sysfs_remove_link(&cdev->cdev.kobj, "device");
  
  	return error;
  }
  
  static void enclosure_release(struct device *cdev)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev);
  
  	put_device(cdev->parent);
  	kfree(edev);
  }
  
  static void enclosure_component_release(struct device *dev)
  {
  	struct enclosure_component *cdev = to_enclosure_component(dev);
  
  	if (cdev->dev) {
  		enclosure_remove_links(cdev);
  		put_device(cdev->dev);
  	}
  	put_device(dev->parent);
  }
  
  static const struct attribute_group *enclosure_component_groups[];
  
  /**
   * enclosure_component_register - add a particular component to an enclosure
   * @edev:	the enclosure to add the component
   * @num:	the device number
   * @type:	the type of component being added
   * @name:	an optional name to appear in sysfs (leave NULL if none)
   *
   * Registers the component.  The name is optional for enclosures that
   * give their components a unique name.  If not, leave the field NULL
   * and a name will be assigned.
   *
   * Returns a pointer to the enclosure component or an error.
   */
  struct enclosure_component *
  enclosure_component_register(struct enclosure_device *edev,
  			     unsigned int number,
  			     enum enclosure_component_type type,
  			     const char *name)
  {
  	struct enclosure_component *ecomp;
  	struct device *cdev;
  	int err;
  
  	if (number >= edev->components)
  		return ERR_PTR(-EINVAL);
  
  	ecomp = &edev->component[number];
  
  	if (ecomp->number != -1)
  		return ERR_PTR(-EINVAL);
  
  	ecomp->type = type;
  	ecomp->number = number;
  	cdev = &ecomp->cdev;
  	cdev->parent = get_device(&edev->edev);
  	if (name && name[0])
  		dev_set_name(cdev, "%s", name);
  	else
  		dev_set_name(cdev, "%u", number);
  
  	cdev->release = enclosure_component_release;
  	cdev->groups = enclosure_component_groups;
  
  	err = device_register(cdev);
  	if (err) {
  		ecomp->number = -1;
  		put_device(cdev);
  		return ERR_PTR(err);
  	}
  
  	return ecomp;
  }
  EXPORT_SYMBOL_GPL(enclosure_component_register);
  
  /**
   * enclosure_add_device - add a device as being part of an enclosure
   * @edev:	the enclosure device being added to.
   * @num:	the number of the component
   * @dev:	the device being added
   *
   * Declares a real device to reside in slot (or identifier) @num of an
   * enclosure.  This will cause the relevant sysfs links to appear.
   * This function may also be used to change a device associated with
   * an enclosure without having to call enclosure_remove_device() in
   * between.
   *
   * Returns zero on success or an error.
   */
  int enclosure_add_device(struct enclosure_device *edev, int component,
  			 struct device *dev)
  {
  	struct enclosure_component *cdev;
  
  	if (!edev || component >= edev->components)
  		return -EINVAL;
  
  	cdev = &edev->component[component];
  
  	if (cdev->dev == dev)
  		return -EEXIST;
  
  	if (cdev->dev)
  		enclosure_remove_links(cdev);
  
  	put_device(cdev->dev);
  	cdev->dev = get_device(dev);
  	return enclosure_add_links(cdev);
  }
  EXPORT_SYMBOL_GPL(enclosure_add_device);
  
  /**
   * enclosure_remove_device - remove a device from an enclosure
   * @edev:	the enclosure device
   * @num:	the number of the component to remove
   *
   * Returns zero on success or an error.
   *
   */
  int enclosure_remove_device(struct enclosure_device *edev, struct device *dev)
  {
  	struct enclosure_component *cdev;
  	int i;
  
  	if (!edev || !dev)
  		return -EINVAL;
  
  	for (i = 0; i < edev->components; i++) {
  		cdev = &edev->component[i];
  		if (cdev->dev == dev) {
  			enclosure_remove_links(cdev);
  			device_del(&cdev->cdev);
  			put_device(dev);
  			cdev->dev = NULL;
  			return device_add(&cdev->cdev);
  		}
  	}
  	return -ENODEV;
  }
  EXPORT_SYMBOL_GPL(enclosure_remove_device);
  
  /*
   * sysfs pieces below
   */
  
  static ssize_t components_show(struct device *cdev,
  			       struct device_attribute *attr, char *buf)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev);
  
  	return snprintf(buf, 40, "%d
  ", edev->components);
  }
  static DEVICE_ATTR_RO(components);
  
  static struct attribute *enclosure_class_attrs[] = {
  	&dev_attr_components.attr,
  	NULL,
  };
  ATTRIBUTE_GROUPS(enclosure_class);
  
  static struct class enclosure_class = {
  	.name			= "enclosure",
  	.owner			= THIS_MODULE,
  	.dev_release		= enclosure_release,
  	.dev_groups		= enclosure_class_groups,
  };
  
  static const char *const enclosure_status [] = {
  	[ENCLOSURE_STATUS_UNSUPPORTED] = "unsupported",
  	[ENCLOSURE_STATUS_OK] = "OK",
  	[ENCLOSURE_STATUS_CRITICAL] = "critical",
  	[ENCLOSURE_STATUS_NON_CRITICAL] = "non-critical",
  	[ENCLOSURE_STATUS_UNRECOVERABLE] = "unrecoverable",
  	[ENCLOSURE_STATUS_NOT_INSTALLED] = "not installed",
  	[ENCLOSURE_STATUS_UNKNOWN] = "unknown",
  	[ENCLOSURE_STATUS_UNAVAILABLE] = "unavailable",
  	[ENCLOSURE_STATUS_MAX] = NULL,
  };
  
  static const char *const enclosure_type [] = {
  	[ENCLOSURE_COMPONENT_DEVICE] = "device",
  	[ENCLOSURE_COMPONENT_ARRAY_DEVICE] = "array device",
  };
  
  static ssize_t get_component_fault(struct device *cdev,
  				   struct device_attribute *attr, char *buf)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  
  	if (edev->cb->get_fault)
  		edev->cb->get_fault(edev, ecomp);
  	return snprintf(buf, 40, "%d
  ", ecomp->fault);
  }
  
  static ssize_t set_component_fault(struct device *cdev,
  				   struct device_attribute *attr,
  				   const char *buf, size_t count)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  	int val = simple_strtoul(buf, NULL, 0);
  
  	if (edev->cb->set_fault)
  		edev->cb->set_fault(edev, ecomp, val);
  	return count;
  }
  
  static ssize_t get_component_status(struct device *cdev,
  				    struct device_attribute *attr,char *buf)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  
  	if (edev->cb->get_status)
  		edev->cb->get_status(edev, ecomp);
  	return snprintf(buf, 40, "%s
  ", enclosure_status[ecomp->status]);
  }
  
  static ssize_t set_component_status(struct device *cdev,
  				    struct device_attribute *attr,
  				    const char *buf, size_t count)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  	int i;
  
  	for (i = 0; enclosure_status[i]; i++) {
  		if (strncmp(buf, enclosure_status[i],
  			    strlen(enclosure_status[i])) == 0 &&
  		    (buf[strlen(enclosure_status[i])] == '
  ' ||
  		     buf[strlen(enclosure_status[i])] == '\0'))
  			break;
  	}
  
  	if (enclosure_status[i] && edev->cb->set_status) {
  		edev->cb->set_status(edev, ecomp, i);
  		return count;
  	} else
  		return -EINVAL;
  }
  
  static ssize_t get_component_active(struct device *cdev,
  				    struct device_attribute *attr, char *buf)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  
  	if (edev->cb->get_active)
  		edev->cb->get_active(edev, ecomp);
  	return snprintf(buf, 40, "%d
  ", ecomp->active);
  }
  
  static ssize_t set_component_active(struct device *cdev,
  				    struct device_attribute *attr,
  				    const char *buf, size_t count)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  	int val = simple_strtoul(buf, NULL, 0);
  
  	if (edev->cb->set_active)
  		edev->cb->set_active(edev, ecomp, val);
  	return count;
  }
  
  static ssize_t get_component_locate(struct device *cdev,
  				    struct device_attribute *attr, char *buf)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  
  	if (edev->cb->get_locate)
  		edev->cb->get_locate(edev, ecomp);
  	return snprintf(buf, 40, "%d
  ", ecomp->locate);
  }
  
  static ssize_t set_component_locate(struct device *cdev,
  				    struct device_attribute *attr,
  				    const char *buf, size_t count)
  {
  	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  	int val = simple_strtoul(buf, NULL, 0);
  
  	if (edev->cb->set_locate)
  		edev->cb->set_locate(edev, ecomp, val);
  	return count;
  }
  
  static ssize_t get_component_type(struct device *cdev,
  				  struct device_attribute *attr, char *buf)
  {
  	struct enclosure_component *ecomp = to_enclosure_component(cdev);
  
  	return snprintf(buf, 40, "%s
  ", enclosure_type[ecomp->type]);
  }
  
  
  static DEVICE_ATTR(fault, S_IRUGO | S_IWUSR, get_component_fault,
  		    set_component_fault);
  static DEVICE_ATTR(status, S_IRUGO | S_IWUSR, get_component_status,
  		   set_component_status);
  static DEVICE_ATTR(active, S_IRUGO | S_IWUSR, get_component_active,
  		   set_component_active);
  static DEVICE_ATTR(locate, S_IRUGO | S_IWUSR, get_component_locate,
  		   set_component_locate);
  static DEVICE_ATTR(type, S_IRUGO, get_component_type, NULL);
  
  static struct attribute *enclosure_component_attrs[] = {
  	&dev_attr_fault.attr,
  	&dev_attr_status.attr,
  	&dev_attr_active.attr,
  	&dev_attr_locate.attr,
  	&dev_attr_type.attr,
  	NULL
  };
  ATTRIBUTE_GROUPS(enclosure_component);
  
  static int __init enclosure_init(void)
  {
  	int err;
  
  	err = class_register(&enclosure_class);
  	if (err)
  		return err;
  
  	return 0;
  }
  
  static void __exit enclosure_exit(void)
  {
  	class_unregister(&enclosure_class);
  }
  
  module_init(enclosure_init);
  module_exit(enclosure_exit);
  
  MODULE_AUTHOR("James Bottomley");
  MODULE_DESCRIPTION("Enclosure Services");
  MODULE_LICENSE("GPL v2");