/*
 * 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\n", 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\n", 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\n", 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])] == '\n' ||
                     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\n", 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\n", 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\n", 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");