/*
 * zfcp device driver
 *
 * Tracking of manually configured LUNs and helper functions to
 * register the LUNs with the SCSI midlayer.
 *
 * Copyright IBM Corp. 2010
 */

#include "zfcp_def.h"
#include "zfcp_ext.h"

/**
 * zfcp_unit_scsi_scan - Register LUN with SCSI midlayer
 * @unit: The zfcp LUN/unit to register
 *
 * When the SCSI midlayer is not allowed to automatically scan and
 * attach SCSI devices, zfcp has to register the single devices with
 * the SCSI midlayer.
 */
void zfcp_unit_scsi_scan(struct zfcp_unit *unit)
{
        struct fc_rport *rport = unit->port->rport;
        u64 lun;

        lun = scsilun_to_int((struct scsi_lun *) &unit->fcp_lun);

        if (rport && rport->port_state == FC_PORTSTATE_ONLINE)
                scsi_scan_target(&rport->dev, 0, rport->scsi_target_id, lun, 1);
}

static void zfcp_unit_scsi_scan_work(struct work_struct *work)
{
        struct zfcp_unit *unit = container_of(work, struct zfcp_unit,
                                              scsi_work);

        zfcp_unit_scsi_scan(unit);
        put_device(&unit->dev);
}

/**
 * zfcp_unit_queue_scsi_scan - Register configured units on port
 * @port: The zfcp_port where to register units
 *
 * After opening a port, all units configured on this port have to be
 * registered with the SCSI midlayer. This function should be called
 * after calling fc_remote_port_add, so that the fc_rport is already
 * ONLINE and the call to scsi_scan_target runs the same way as the
 * call in the FC transport class.
 */
void zfcp_unit_queue_scsi_scan(struct zfcp_port *port)
{
        struct zfcp_unit *unit;

        read_lock_irq(&port->unit_list_lock);
        list_for_each_entry(unit, &port->unit_list, list) {
                get_device(&unit->dev);
                if (scsi_queue_work(port->adapter->scsi_host,
                                    &unit->scsi_work) <= 0)
                        put_device(&unit->dev);
        }
        read_unlock_irq(&port->unit_list_lock);
}

static struct zfcp_unit *_zfcp_unit_find(struct zfcp_port *port, u64 fcp_lun)
{
        struct zfcp_unit *unit;

        list_for_each_entry(unit, &port->unit_list, list)
                if (unit->fcp_lun == fcp_lun) {
                        get_device(&unit->dev);
                        return unit;
                }

        return NULL;
}

/**
 * zfcp_unit_find - Find and return zfcp_unit with specified FCP LUN
 * @port: zfcp_port where to look for the unit
 * @fcp_lun: 64 Bit FCP LUN used to identify the zfcp_unit
 *
 * If zfcp_unit is found, a reference is acquired that has to be
 * released later.
 *
 * Returns: Pointer to the zfcp_unit, or NULL if there is no zfcp_unit
 *          with the specified FCP LUN.
 */
struct zfcp_unit *zfcp_unit_find(struct zfcp_port *port, u64 fcp_lun)
{
        struct zfcp_unit *unit;

        read_lock_irq(&port->unit_list_lock);
        unit = _zfcp_unit_find(port, fcp_lun);
        read_unlock_irq(&port->unit_list_lock);
        return unit;
}

/**
 * zfcp_unit_release - Drop reference to zfcp_port and free memory of zfcp_unit.
 * @dev: pointer to device in zfcp_unit
 */
static void zfcp_unit_release(struct device *dev)
{
        struct zfcp_unit *unit = container_of(dev, struct zfcp_unit, dev);

        atomic_dec(&unit->port->units);
        kfree(unit);
}

/**
 * zfcp_unit_enqueue - enqueue unit to unit list of a port.
 * @port: pointer to port where unit is added
 * @fcp_lun: FCP LUN of unit to be enqueued
 * Returns: 0 success
 *
 * Sets up some unit internal structures and creates sysfs entry.
 */
int zfcp_unit_add(struct zfcp_port *port, u64 fcp_lun)
{
        struct zfcp_unit *unit;
        int retval = 0;

        mutex_lock(&zfcp_sysfs_port_units_mutex);
        if (atomic_read(&port->units) == -1) {
                /* port is already gone */
                retval = -ENODEV;
                goto out;
        }

        unit = zfcp_unit_find(port, fcp_lun);
        if (unit) {
                put_device(&unit->dev);
                retval = -EEXIST;
                goto out;
        }

        unit = kzalloc(sizeof(struct zfcp_unit), GFP_KERNEL);
        if (!unit) {
                retval = -ENOMEM;
                goto out;
        }

        unit->port = port;
        unit->fcp_lun = fcp_lun;
        unit->dev.parent = &port->dev;
        unit->dev.release = zfcp_unit_release;
        unit->dev.groups = zfcp_unit_attr_groups;
        INIT_WORK(&unit->scsi_work, zfcp_unit_scsi_scan_work);

        if (dev_set_name(&unit->dev, "0x%016llx",
                         (unsigned long long) fcp_lun)) {
                kfree(unit);
                retval = -ENOMEM;
                goto out;
        }

        if (device_register(&unit->dev)) {
                put_device(&unit->dev);
                retval = -ENOMEM;
                goto out;
        }

        atomic_inc(&port->units); /* under zfcp_sysfs_port_units_mutex ! */

        write_lock_irq(&port->unit_list_lock);
        list_add_tail(&unit->list, &port->unit_list);
        write_unlock_irq(&port->unit_list_lock);

        zfcp_unit_scsi_scan(unit);

out:
        mutex_unlock(&zfcp_sysfs_port_units_mutex);
        return retval;
}

/**
 * zfcp_unit_sdev - Return SCSI device for zfcp_unit
 * @unit: The zfcp_unit where to get the SCSI device for
 *
 * Returns: scsi_device pointer on success, NULL if there is no SCSI
 *          device for this zfcp_unit
 *
 * On success, the caller also holds a reference to the SCSI device
 * that must be released with scsi_device_put.
 */
struct scsi_device *zfcp_unit_sdev(struct zfcp_unit *unit)
{
        struct Scsi_Host *shost;
        struct zfcp_port *port;
        u64 lun;

        lun = scsilun_to_int((struct scsi_lun *) &unit->fcp_lun);
        port = unit->port;
        shost = port->adapter->scsi_host;
        return scsi_device_lookup(shost, 0, port->starget_id, lun);
}

/**
 * zfcp_unit_sdev_status - Return zfcp LUN status for SCSI device
 * @unit: The unit to lookup the SCSI device for
 *
 * Returns the zfcp LUN status field of the SCSI device if the SCSI device
 * for the zfcp_unit exists, 0 otherwise.
 */
unsigned int zfcp_unit_sdev_status(struct zfcp_unit *unit)
{
        unsigned int status = 0;
        struct scsi_device *sdev;
        struct zfcp_scsi_dev *zfcp_sdev;

        sdev = zfcp_unit_sdev(unit);
        if (sdev) {
                zfcp_sdev = sdev_to_zfcp(sdev);
                status = atomic_read(&zfcp_sdev->status);
                scsi_device_put(sdev);
        }

        return status;
}

/**
 * zfcp_unit_remove - Remove entry from list of configured units
 * @port: The port where to remove the unit from the configuration
 * @fcp_lun: The 64 bit LUN of the unit to remove
 *
 * Returns: -EINVAL if a unit with the specified LUN does not exist,
 *          0 on success.
 */
int zfcp_unit_remove(struct zfcp_port *port, u64 fcp_lun)
{
        struct zfcp_unit *unit;
        struct scsi_device *sdev;

        write_lock_irq(&port->unit_list_lock);
        unit = _zfcp_unit_find(port, fcp_lun);
        if (unit)
                list_del(&unit->list);
        write_unlock_irq(&port->unit_list_lock);

        if (!unit)
                return -EINVAL;

        sdev = zfcp_unit_sdev(unit);
        if (sdev) {
                scsi_remove_device(sdev);
                scsi_device_put(sdev);
        }

        put_device(&unit->dev);

        device_unregister(&unit->dev);

        return 0;
}