Linux 3.11-rc3

[cris-mirror.git] / drivers / ata / libata-transport.c

/*
 *  Copyright 2008 ioogle, Inc.  All rights reserved.
 *      Released under GPL v2.
 *
 * Libata transport class.
 *
 * The ATA transport class contains common code to deal with ATA HBAs,
 * an approximated representation of ATA topologies in the driver model,
 * and various sysfs attributes to expose these topologies and management
 * interfaces to user-space.
 *
 * There are 3 objects defined in in this class:
 * - ata_port
 * - ata_link
 * - ata_device
 * Each port has a link object. Each link can have up to two devices for PATA
 * and generally one for SATA.
 * If there is SATA port multiplier [PMP], 15 additional ata_link object are
 * created.
 *
 * These objects are created when the ata host is initialized and when a PMP is
 * found. They are removed only when the HBA is removed, cleaned before the
 * error handler runs.
 */


#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <scsi/scsi_transport.h>
#include <linux/libata.h>
#include <linux/hdreg.h>
#include <linux/uaccess.h>
#include <linux/pm_runtime.h>

#include "libata.h"
#include "libata-transport.h"

#define ATA_PORT_ATTRS          3
#define ATA_LINK_ATTRS          3
#define ATA_DEV_ATTRS           9

struct scsi_transport_template;
struct scsi_transport_template *ata_scsi_transport_template;

struct ata_internal {
        struct scsi_transport_template t;

        struct device_attribute private_port_attrs[ATA_PORT_ATTRS];
        struct device_attribute private_link_attrs[ATA_LINK_ATTRS];
        struct device_attribute private_dev_attrs[ATA_DEV_ATTRS];

        struct transport_container link_attr_cont;
        struct transport_container dev_attr_cont;

        /*
         * The array of null terminated pointers to attributes
         * needed by scsi_sysfs.c
         */
        struct device_attribute *link_attrs[ATA_LINK_ATTRS + 1];
        struct device_attribute *port_attrs[ATA_PORT_ATTRS + 1];
        struct device_attribute *dev_attrs[ATA_DEV_ATTRS + 1];
};
#define to_ata_internal(tmpl)   container_of(tmpl, struct ata_internal, t)


#define tdev_to_device(d)                                       \
        container_of((d), struct ata_device, tdev)
#define transport_class_to_dev(dev)                             \
        tdev_to_device((dev)->parent)

#define tdev_to_link(d)                                         \
        container_of((d), struct ata_link, tdev)
#define transport_class_to_link(dev)                            \
        tdev_to_link((dev)->parent)

#define tdev_to_port(d)                                         \
        container_of((d), struct ata_port, tdev)
#define transport_class_to_port(dev)                            \
        tdev_to_port((dev)->parent)


/* Device objects are always created whit link objects */
static int ata_tdev_add(struct ata_device *dev);
static void ata_tdev_delete(struct ata_device *dev);


/*
 * Hack to allow attributes of the same name in different objects.
 */
#define ATA_DEVICE_ATTR(_prefix,_name,_mode,_show,_store) \
        struct device_attribute device_attr_##_prefix##_##_name = \
        __ATTR(_name,_mode,_show,_store)

#define ata_bitfield_name_match(title, table)                   \
static ssize_t                                                  \
get_ata_##title##_names(u32 table_key, char *buf)               \
{                                                               \
        char *prefix = "";                                      \
        ssize_t len = 0;                                        \
        int i;                                                  \
                                                                \
        for (i = 0; i < ARRAY_SIZE(table); i++) {               \
                if (table[i].value & table_key) {               \
                        len += sprintf(buf + len, "%s%s",       \
                                prefix, table[i].name);         \
                        prefix = ", ";                          \
                }                                               \
        }                                                       \
        len += sprintf(buf + len, "\n");                        \
        return len;                                             \
}

#define ata_bitfield_name_search(title, table)                  \
static ssize_t                                                  \
get_ata_##title##_names(u32 table_key, char *buf)               \
{                                                               \
        ssize_t len = 0;                                        \
        int i;                                                  \
                                                                \
        for (i = 0; i < ARRAY_SIZE(table); i++) {               \
                if (table[i].value == table_key) {              \
                        len += sprintf(buf + len, "%s",         \
                                table[i].name);                 \
                        break;                                  \
                }                                               \
        }                                                       \
        len += sprintf(buf + len, "\n");                        \
        return len;                                             \
}

static struct {
        u32             value;
        char            *name;
} ata_class_names[] = {
        { ATA_DEV_UNKNOWN,              "unknown" },
        { ATA_DEV_ATA,                  "ata" },
        { ATA_DEV_ATA_UNSUP,            "ata" },
        { ATA_DEV_ATAPI,                "atapi" },
        { ATA_DEV_ATAPI_UNSUP,          "atapi" },
        { ATA_DEV_PMP,                  "pmp" },
        { ATA_DEV_PMP_UNSUP,            "pmp" },
        { ATA_DEV_SEMB,                 "semb" },
        { ATA_DEV_SEMB_UNSUP,           "semb" },
        { ATA_DEV_NONE,                 "none" }
};
ata_bitfield_name_search(class, ata_class_names)


static struct {
        u32             value;
        char            *name;
} ata_err_names[] = {
        { AC_ERR_DEV,                   "DeviceError" },
        { AC_ERR_HSM,                   "HostStateMachineError" },
        { AC_ERR_TIMEOUT,               "Timeout" },
        { AC_ERR_MEDIA,                 "MediaError" },
        { AC_ERR_ATA_BUS,               "BusError" },
        { AC_ERR_HOST_BUS,              "HostBusError" },
        { AC_ERR_SYSTEM,                "SystemError" },
        { AC_ERR_INVALID,               "InvalidArg" },
        { AC_ERR_OTHER,                 "Unknown" },
        { AC_ERR_NODEV_HINT,            "NoDeviceHint" },
        { AC_ERR_NCQ,                   "NCQError" }
};
ata_bitfield_name_match(err, ata_err_names)

static struct {
        u32             value;
        char            *name;
} ata_xfer_names[] = {
        { XFER_UDMA_7,                  "XFER_UDMA_7" },
        { XFER_UDMA_6,                  "XFER_UDMA_6" },
        { XFER_UDMA_5,                  "XFER_UDMA_5" },
        { XFER_UDMA_4,                  "XFER_UDMA_4" },
        { XFER_UDMA_3,                  "XFER_UDMA_3" },
        { XFER_UDMA_2,                  "XFER_UDMA_2" },
        { XFER_UDMA_1,                  "XFER_UDMA_1" },
        { XFER_UDMA_0,                  "XFER_UDMA_0" },
        { XFER_MW_DMA_4,                "XFER_MW_DMA_4" },
        { XFER_MW_DMA_3,                "XFER_MW_DMA_3" },
        { XFER_MW_DMA_2,                "XFER_MW_DMA_2" },
        { XFER_MW_DMA_1,                "XFER_MW_DMA_1" },
        { XFER_MW_DMA_0,                "XFER_MW_DMA_0" },
        { XFER_SW_DMA_2,                "XFER_SW_DMA_2" },
        { XFER_SW_DMA_1,                "XFER_SW_DMA_1" },
        { XFER_SW_DMA_0,                "XFER_SW_DMA_0" },
        { XFER_PIO_6,                   "XFER_PIO_6" },
        { XFER_PIO_5,                   "XFER_PIO_5" },
        { XFER_PIO_4,                   "XFER_PIO_4" },
        { XFER_PIO_3,                   "XFER_PIO_3" },
        { XFER_PIO_2,                   "XFER_PIO_2" },
        { XFER_PIO_1,                   "XFER_PIO_1" },
        { XFER_PIO_0,                   "XFER_PIO_0" },
        { XFER_PIO_SLOW,                "XFER_PIO_SLOW" }
};
ata_bitfield_name_match(xfer,ata_xfer_names)

/*
 * ATA Port attributes
 */
#define ata_port_show_simple(field, name, format_string, cast)          \
static ssize_t                                                          \
show_ata_port_##name(struct device *dev,                                \
                     struct device_attribute *attr, char *buf)          \
{                                                                       \
        struct ata_port *ap = transport_class_to_port(dev);             \
                                                                        \
        return snprintf(buf, 20, format_string, cast ap->field);        \
}

#define ata_port_simple_attr(field, name, format_string, type)          \
        ata_port_show_simple(field, name, format_string, (type))        \
static DEVICE_ATTR(name, S_IRUGO, show_ata_port_##name, NULL)

ata_port_simple_attr(nr_pmp_links, nr_pmp_links, "%d\n", int);
ata_port_simple_attr(stats.idle_irq, idle_irq, "%ld\n", unsigned long);
ata_port_simple_attr(local_port_no, port_no, "%u\n", unsigned int);

static DECLARE_TRANSPORT_CLASS(ata_port_class,
                               "ata_port", NULL, NULL, NULL);

static void ata_tport_release(struct device *dev)
{
        put_device(dev->parent);
}

/**
 * ata_is_port --  check if a struct device represents a ATA port
 * @dev:        device to check
 *
 * Returns:
 *      %1 if the device represents a ATA Port, %0 else
 */
static int ata_is_port(const struct device *dev)
{
        return dev->release == ata_tport_release;
}

static int ata_tport_match(struct attribute_container *cont,
                           struct device *dev)
{
        if (!ata_is_port(dev))
                return 0;
        return &ata_scsi_transport_template->host_attrs.ac == cont;
}

/**
 * ata_tport_delete  --  remove ATA PORT
 * @port:       ATA PORT to remove
 *
 * Removes the specified ATA PORT.  Remove the associated link as well.
 */
void ata_tport_delete(struct ata_port *ap)
{
        struct device *dev = &ap->tdev;

        ata_tlink_delete(&ap->link);

        transport_remove_device(dev);
        device_del(dev);
        transport_destroy_device(dev);
        put_device(dev);
}

/** ata_tport_add - initialize a transport ATA port structure
 *
 * @parent:     parent device
 * @ap:         existing ata_port structure
 *
 * Initialize a ATA port structure for sysfs.  It will be added to the device
 * tree below the device specified by @parent which could be a PCI device.
 *
 * Returns %0 on success
 */
int ata_tport_add(struct device *parent,
                  struct ata_port *ap)
{
        int error;
        struct device *dev = &ap->tdev;

        device_initialize(dev);
        dev->type = &ata_port_type;

        dev->parent = get_device(parent);
        dev->release = ata_tport_release;
        dev_set_name(dev, "ata%d", ap->print_id);
        transport_setup_device(dev);
        error = device_add(dev);
        if (error) {
                goto tport_err;
        }

        device_enable_async_suspend(dev);
        pm_runtime_set_active(dev);
        pm_runtime_enable(dev);
        pm_runtime_forbid(dev);

        transport_add_device(dev);
        transport_configure_device(dev);

        error = ata_tlink_add(&ap->link);
        if (error) {
                goto tport_link_err;
        }
        return 0;

 tport_link_err:
        transport_remove_device(dev);
        device_del(dev);

 tport_err:
        transport_destroy_device(dev);
        put_device(dev);
        return error;
}


/*
 * ATA link attributes
 */


#define ata_link_show_linkspeed(field)                                  \
static ssize_t                                                          \
show_ata_link_##field(struct device *dev,                               \
                      struct device_attribute *attr, char *buf)         \
{                                                                       \
        struct ata_link *link = transport_class_to_link(dev);           \
                                                                        \
        return sprintf(buf,"%s\n", sata_spd_string(fls(link->field)));  \
}

#define ata_link_linkspeed_attr(field)                                  \
        ata_link_show_linkspeed(field)                                  \
static DEVICE_ATTR(field, S_IRUGO, show_ata_link_##field, NULL)

ata_link_linkspeed_attr(hw_sata_spd_limit);
ata_link_linkspeed_attr(sata_spd_limit);
ata_link_linkspeed_attr(sata_spd);


static DECLARE_TRANSPORT_CLASS(ata_link_class,
                "ata_link", NULL, NULL, NULL);

static void ata_tlink_release(struct device *dev)
{
        put_device(dev->parent);
}

/**
 * ata_is_link --  check if a struct device represents a ATA link
 * @dev:        device to check
 *
 * Returns:
 *      %1 if the device represents a ATA link, %0 else
 */
static int ata_is_link(const struct device *dev)
{
        return dev->release == ata_tlink_release;
}

static int ata_tlink_match(struct attribute_container *cont,
                           struct device *dev)
{
        struct ata_internal* i = to_ata_internal(ata_scsi_transport_template);
        if (!ata_is_link(dev))
                return 0;
        return &i->link_attr_cont.ac == cont;
}

/**
 * ata_tlink_delete  --  remove ATA LINK
 * @port:       ATA LINK to remove
 *
 * Removes the specified ATA LINK.  remove associated ATA device(s) as well.
 */
void ata_tlink_delete(struct ata_link *link)
{
        struct device *dev = &link->tdev;
        struct ata_device *ata_dev;

        ata_for_each_dev(ata_dev, link, ALL) {
                ata_tdev_delete(ata_dev);
        }

        transport_remove_device(dev);
        device_del(dev);
        transport_destroy_device(dev);
        put_device(dev);
}

/**
 * ata_tlink_add  --  initialize a transport ATA link structure
 * @link:       allocated ata_link structure.
 *
 * Initialize an ATA LINK structure for sysfs.  It will be added in the
 * device tree below the ATA PORT it belongs to.
 *
 * Returns %0 on success
 */
int ata_tlink_add(struct ata_link *link)
{
        struct device *dev = &link->tdev;
        struct ata_port *ap = link->ap;
        struct ata_device *ata_dev;
        int error;

        device_initialize(dev);
        dev->parent = get_device(&ap->tdev);
        dev->release = ata_tlink_release;
        if (ata_is_host_link(link))
                dev_set_name(dev, "link%d", ap->print_id);
        else
                dev_set_name(dev, "link%d.%d", ap->print_id, link->pmp);

        transport_setup_device(dev);

        error = device_add(dev);
        if (error) {
                goto tlink_err;
        }

        transport_add_device(dev);
        transport_configure_device(dev);

        ata_for_each_dev(ata_dev, link, ALL) {
                error = ata_tdev_add(ata_dev);
                if (error) {
                        goto tlink_dev_err;
                }
        }
        return 0;
  tlink_dev_err:
        while (--ata_dev >= link->device) {
                ata_tdev_delete(ata_dev);
        }
        transport_remove_device(dev);
        device_del(dev);
  tlink_err:
        transport_destroy_device(dev);
        put_device(dev);
        return error;
}

/*
 * ATA device attributes
 */

#define ata_dev_show_class(title, field)                                \
static ssize_t                                                          \
show_ata_dev_##field(struct device *dev,                                \
                     struct device_attribute *attr, char *buf)          \
{                                                                       \
        struct ata_device *ata_dev = transport_class_to_dev(dev);       \
                                                                        \
        return get_ata_##title##_names(ata_dev->field, buf);            \
}

#define ata_dev_attr(title, field)                                      \
        ata_dev_show_class(title, field)                                \
static DEVICE_ATTR(field, S_IRUGO, show_ata_dev_##field, NULL)

ata_dev_attr(class, class);
ata_dev_attr(xfer, pio_mode);
ata_dev_attr(xfer, dma_mode);
ata_dev_attr(xfer, xfer_mode);


#define ata_dev_show_simple(field, format_string, cast)         \
static ssize_t                                                          \
show_ata_dev_##field(struct device *dev,                                \
                     struct device_attribute *attr, char *buf)          \
{                                                                       \
        struct ata_device *ata_dev = transport_class_to_dev(dev);       \
                                                                        \
        return snprintf(buf, 20, format_string, cast ata_dev->field);   \
}

#define ata_dev_simple_attr(field, format_string, type) \
        ata_dev_show_simple(field, format_string, (type))       \
static DEVICE_ATTR(field, S_IRUGO,                      \
                   show_ata_dev_##field, NULL)

ata_dev_simple_attr(spdn_cnt, "%d\n", int);

struct ata_show_ering_arg {
        char* buf;
        int written;
};

static int ata_show_ering(struct ata_ering_entry *ent, void *void_arg)
{
        struct ata_show_ering_arg* arg = void_arg;
        struct timespec time;

        jiffies_to_timespec(ent->timestamp,&time);
        arg->written += sprintf(arg->buf + arg->written,
                               "[%5lu.%06lu]",
                               time.tv_sec, time.tv_nsec);
        arg->written += get_ata_err_names(ent->err_mask,
                                          arg->buf + arg->written);
        return 0;
}

static ssize_t
show_ata_dev_ering(struct device *dev,
                   struct device_attribute *attr, char *buf)
{
        struct ata_device *ata_dev = transport_class_to_dev(dev);
        struct ata_show_ering_arg arg = { buf, 0 };

        ata_ering_map(&ata_dev->ering, ata_show_ering, &arg);
        return arg.written;
}


static DEVICE_ATTR(ering, S_IRUGO, show_ata_dev_ering, NULL);

static ssize_t
show_ata_dev_id(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct ata_device *ata_dev = transport_class_to_dev(dev);
        int written = 0, i = 0;

        if (ata_dev->class == ATA_DEV_PMP)
                return 0;
        for(i=0;i<ATA_ID_WORDS;i++)  {
                written += snprintf(buf+written, 20, "%04x%c",
                                    ata_dev->id[i],
                                    ((i+1) & 7) ? ' ' : '\n');
        }
        return written;
}

static DEVICE_ATTR(id, S_IRUGO, show_ata_dev_id, NULL);

static ssize_t
show_ata_dev_gscr(struct device *dev,
                  struct device_attribute *attr, char *buf)
{
        struct ata_device *ata_dev = transport_class_to_dev(dev);
        int written = 0, i = 0;

        if (ata_dev->class != ATA_DEV_PMP)
                return 0;
        for(i=0;i<SATA_PMP_GSCR_DWORDS;i++)  {
                written += snprintf(buf+written, 20, "%08x%c",
                                    ata_dev->gscr[i],
                                    ((i+1) & 3) ? ' ' : '\n');
        }
        if (SATA_PMP_GSCR_DWORDS & 3)
                buf[written-1] = '\n';
        return written;
}

static DEVICE_ATTR(gscr, S_IRUGO, show_ata_dev_gscr, NULL);

static DECLARE_TRANSPORT_CLASS(ata_dev_class,
                               "ata_device", NULL, NULL, NULL);

static void ata_tdev_release(struct device *dev)
{
        put_device(dev->parent);
}

/**
 * ata_is_ata_dev  --  check if a struct device represents a ATA device
 * @dev:        device to check
 *
 * Returns:
 *      %1 if the device represents a ATA device, %0 else
 */
static int ata_is_ata_dev(const struct device *dev)
{
        return dev->release == ata_tdev_release;
}

static int ata_tdev_match(struct attribute_container *cont,
                          struct device *dev)
{
        struct ata_internal* i = to_ata_internal(ata_scsi_transport_template);
        if (!ata_is_ata_dev(dev))
                return 0;
        return &i->dev_attr_cont.ac == cont;
}

/**
 * ata_tdev_free  --  free a ATA LINK
 * @dev:        ATA PHY to free
 *
 * Frees the specified ATA PHY.
 *
 * Note:
 *   This function must only be called on a PHY that has not
 *   successfully been added using ata_tdev_add().
 */
static void ata_tdev_free(struct ata_device *dev)
{
        transport_destroy_device(&dev->tdev);
        put_device(&dev->tdev);
}

/**
 * ata_tdev_delete  --  remove ATA device
 * @port:       ATA PORT to remove
 *
 * Removes the specified ATA device.
 */
static void ata_tdev_delete(struct ata_device *ata_dev)
{
        struct device *dev = &ata_dev->tdev;

        transport_remove_device(dev);
        device_del(dev);
        ata_tdev_free(ata_dev);
}


/**
 * ata_tdev_add  --  initialize a transport ATA device structure.
 * @ata_dev:    ata_dev structure.
 *
 * Initialize an ATA device structure for sysfs.  It will be added in the
 * device tree below the ATA LINK device it belongs to.
 *
 * Returns %0 on success
 */
static int ata_tdev_add(struct ata_device *ata_dev)
{
        struct device *dev = &ata_dev->tdev;
        struct ata_link *link = ata_dev->link;
        struct ata_port *ap = link->ap;
        int error;

        device_initialize(dev);
        dev->parent = get_device(&link->tdev);
        dev->release = ata_tdev_release;
        if (ata_is_host_link(link))
                dev_set_name(dev, "dev%d.%d", ap->print_id,ata_dev->devno);
        else
                dev_set_name(dev, "dev%d.%d.0", ap->print_id, link->pmp);

        transport_setup_device(dev);
        error = device_add(dev);
        if (error) {
                ata_tdev_free(ata_dev);
                return error;
        }

        transport_add_device(dev);
        transport_configure_device(dev);
        return 0;
}


/*
 * Setup / Teardown code
 */

#define SETUP_TEMPLATE(attrb, field, perm, test)                        \
        i->private_##attrb[count] = dev_attr_##field;                   \
        i->private_##attrb[count].attr.mode = perm;                     \
        i->attrb[count] = &i->private_##attrb[count];                   \
        if (test)                                                       \
                count++

#define SETUP_LINK_ATTRIBUTE(field)                                     \
        SETUP_TEMPLATE(link_attrs, field, S_IRUGO, 1)

#define SETUP_PORT_ATTRIBUTE(field)                                     \
        SETUP_TEMPLATE(port_attrs, field, S_IRUGO, 1)

#define SETUP_DEV_ATTRIBUTE(field)                                      \
        SETUP_TEMPLATE(dev_attrs, field, S_IRUGO, 1)

/**
 * ata_attach_transport  --  instantiate ATA transport template
 */
struct scsi_transport_template *ata_attach_transport(void)
{
        struct ata_internal *i;
        int count;

        i = kzalloc(sizeof(struct ata_internal), GFP_KERNEL);
        if (!i)
                return NULL;

        i->t.eh_strategy_handler        = ata_scsi_error;
        i->t.eh_timed_out               = ata_scsi_timed_out;
        i->t.user_scan                  = ata_scsi_user_scan;

        i->t.host_attrs.ac.attrs = &i->port_attrs[0];
        i->t.host_attrs.ac.class = &ata_port_class.class;
        i->t.host_attrs.ac.match = ata_tport_match;
        transport_container_register(&i->t.host_attrs);

        i->link_attr_cont.ac.class = &ata_link_class.class;
        i->link_attr_cont.ac.attrs = &i->link_attrs[0];
        i->link_attr_cont.ac.match = ata_tlink_match;
        transport_container_register(&i->link_attr_cont);

        i->dev_attr_cont.ac.class = &ata_dev_class.class;
        i->dev_attr_cont.ac.attrs = &i->dev_attrs[0];
        i->dev_attr_cont.ac.match = ata_tdev_match;
        transport_container_register(&i->dev_attr_cont);

        count = 0;
        SETUP_PORT_ATTRIBUTE(nr_pmp_links);
        SETUP_PORT_ATTRIBUTE(idle_irq);
        SETUP_PORT_ATTRIBUTE(port_no);
        BUG_ON(count > ATA_PORT_ATTRS);
        i->port_attrs[count] = NULL;

        count = 0;
        SETUP_LINK_ATTRIBUTE(hw_sata_spd_limit);
        SETUP_LINK_ATTRIBUTE(sata_spd_limit);
        SETUP_LINK_ATTRIBUTE(sata_spd);
        BUG_ON(count > ATA_LINK_ATTRS);
        i->link_attrs[count] = NULL;

        count = 0;
        SETUP_DEV_ATTRIBUTE(class);
        SETUP_DEV_ATTRIBUTE(pio_mode);
        SETUP_DEV_ATTRIBUTE(dma_mode);
        SETUP_DEV_ATTRIBUTE(xfer_mode);
        SETUP_DEV_ATTRIBUTE(spdn_cnt);
        SETUP_DEV_ATTRIBUTE(ering);
        SETUP_DEV_ATTRIBUTE(id);
        SETUP_DEV_ATTRIBUTE(gscr);
        BUG_ON(count > ATA_DEV_ATTRS);
        i->dev_attrs[count] = NULL;

        return &i->t;
}

/**
 * ata_release_transport  --  release ATA transport template instance
 * @t:          transport template instance
 */
void ata_release_transport(struct scsi_transport_template *t)
{
        struct ata_internal *i = to_ata_internal(t);

        transport_container_unregister(&i->t.host_attrs);
        transport_container_unregister(&i->link_attr_cont);
        transport_container_unregister(&i->dev_attr_cont);

        kfree(i);
}

__init int libata_transport_init(void)
{
        int error;

        error = transport_class_register(&ata_link_class);
        if (error)
                goto out_unregister_transport;
        error = transport_class_register(&ata_port_class);
        if (error)
                goto out_unregister_link;
        error = transport_class_register(&ata_dev_class);
        if (error)
                goto out_unregister_port;
        return 0;

 out_unregister_port:
        transport_class_unregister(&ata_port_class);
 out_unregister_link:
        transport_class_unregister(&ata_link_class);
 out_unregister_transport:
        return error;

}

void __exit libata_transport_exit(void)
{
        transport_class_unregister(&ata_link_class);
        transport_class_unregister(&ata_port_class);
        transport_class_unregister(&ata_dev_class);
}