/*
 *  dock.c - ACPI dock station driver
 *
 *  Copyright (C) 2006 Kristen Carlson Accardi <kristen.c.accardi@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  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.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/notifier.h>
#include <linux/platform_device.h>
#include <linux/jiffies.h>
#include <linux/stddef.h>
#include <linux/acpi.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>

#include "internal.h"

#define ACPI_DOCK_DRIVER_DESCRIPTION "ACPI Dock Station Driver"

ACPI_MODULE_NAME("dock");
MODULE_AUTHOR("Kristen Carlson Accardi");
MODULE_DESCRIPTION(ACPI_DOCK_DRIVER_DESCRIPTION);
MODULE_LICENSE("GPL");

static bool immediate_undock = 1;
module_param(immediate_undock, bool, 0644);
MODULE_PARM_DESC(immediate_undock, "1 (default) will cause the driver to "
        "undock immediately when the undock button is pressed, 0 will cause"
        " the driver to wait for userspace to write the undock sysfs file "
        " before undocking");

static const struct acpi_device_id dock_device_ids[] = {
        {"LNXDOCK", 0},
        {"", 0},
};
MODULE_DEVICE_TABLE(acpi, dock_device_ids);

struct dock_station {
        acpi_handle handle;
        unsigned long last_dock_time;
        u32 flags;
        struct list_head dependent_devices;

        struct list_head sibling;
        struct platform_device *dock_device;
};
static LIST_HEAD(dock_stations);
static int dock_station_count;
static DEFINE_MUTEX(hotplug_lock);

struct dock_dependent_device {
        struct list_head list;
        struct acpi_device *adev;
        const struct acpi_dock_ops *hp_ops;
        void *hp_context;
        unsigned int hp_refcount;
        void (*hp_release)(void *);
};

#define DOCK_DOCKING    0x00000001
#define DOCK_UNDOCKING  0x00000002
#define DOCK_IS_DOCK    0x00000010
#define DOCK_IS_ATA     0x00000020
#define DOCK_IS_BAT     0x00000040
#define DOCK_EVENT      3
#define UNDOCK_EVENT    2

enum dock_callback_type {
        DOCK_CALL_HANDLER,
        DOCK_CALL_FIXUP,
        DOCK_CALL_UEVENT,
};

/*****************************************************************************
 *                         Dock Dependent device functions                   *
 *****************************************************************************/
/**
 * add_dock_dependent_device - associate a device with the dock station
 * @ds: Dock station.
 * @adev: Dependent ACPI device object.
 *
 * Add the dependent device to the dock's dependent device list.
 */
static int add_dock_dependent_device(struct dock_station *ds,
                                     struct acpi_device *adev)
{
        struct dock_dependent_device *dd;

        dd = kzalloc(sizeof(*dd), GFP_KERNEL);
        if (!dd)
                return -ENOMEM;

        dd->adev = adev;
        INIT_LIST_HEAD(&dd->list);
        list_add_tail(&dd->list, &ds->dependent_devices);

        return 0;
}

static void remove_dock_dependent_devices(struct dock_station *ds)
{
        struct dock_dependent_device *dd, *aux;

        list_for_each_entry_safe(dd, aux, &ds->dependent_devices, list) {
                list_del(&dd->list);
                kfree(dd);
        }
}

/**
 * dock_init_hotplug - Initialize a hotplug device on a docking station.
 * @dd: Dock-dependent device.
 * @ops: Dock operations to attach to the dependent device.
 * @context: Data to pass to the @ops callbacks and @release.
 * @init: Optional initialization routine to run after setting up context.
 * @release: Optional release routine to run on removal.
 */
static int dock_init_hotplug(struct dock_dependent_device *dd,
                             const struct acpi_dock_ops *ops, void *context,
                             void (*init)(void *), void (*release)(void *))
{
        int ret = 0;

        mutex_lock(&hotplug_lock);
        if (WARN_ON(dd->hp_context)) {
                ret = -EEXIST;
        } else {
                dd->hp_refcount = 1;
                dd->hp_ops = ops;
                dd->hp_context = context;
                dd->hp_release = release;
                if (init)
                        init(context);
        }
        mutex_unlock(&hotplug_lock);
        return ret;
}

/**
 * dock_release_hotplug - Decrement hotplug reference counter of dock device.
 * @dd: Dock-dependent device.
 *
 * Decrement the reference counter of @dd and if 0, detach its hotplug
 * operations from it, reset its context pointer and run the optional release
 * routine if present.
 */
static void dock_release_hotplug(struct dock_dependent_device *dd)
{
        mutex_lock(&hotplug_lock);
        if (dd->hp_context && !--dd->hp_refcount) {
                void (*release)(void *) = dd->hp_release;
                void *context = dd->hp_context;

                dd->hp_ops = NULL;
                dd->hp_context = NULL;
                dd->hp_release = NULL;
                if (release)
                        release(context);
        }
        mutex_unlock(&hotplug_lock);
}

static void dock_hotplug_event(struct dock_dependent_device *dd, u32 event,
                               enum dock_callback_type cb_type)
{
        struct acpi_device *adev = dd->adev;
        acpi_notify_handler cb = NULL;
        bool run = false;

        acpi_lock_hp_context();

        if (!adev->hp)
                goto no_context;

        if (cb_type == DOCK_CALL_FIXUP) {
                void (*fixup)(struct acpi_device *);

                fixup = adev->hp->fixup;
                if (fixup) {
                        acpi_unlock_hp_context();
                        fixup(adev);
                        return;
                }
        } else if (cb_type == DOCK_CALL_UEVENT) {
                void (*uevent)(struct acpi_device *, u32);

                uevent = adev->hp->uevent;
                if (uevent) {
                        acpi_unlock_hp_context();
                        uevent(adev, event);
                        return;
                }
        } else {
                int (*notify)(struct acpi_device *, u32);

                notify = adev->hp->notify;
                if (notify) {
                        acpi_unlock_hp_context();
                        notify(adev, event);
                        return;
                }
        }

 no_context:
        acpi_unlock_hp_context();

        mutex_lock(&hotplug_lock);

        if (dd->hp_context) {
                run = true;
                dd->hp_refcount++;
                if (dd->hp_ops) {
                        switch (cb_type) {
                        case DOCK_CALL_FIXUP:
                                cb = dd->hp_ops->fixup;
                                break;
                        case DOCK_CALL_UEVENT:
                                cb = dd->hp_ops->uevent;
                                break;
                        default:
                                cb = dd->hp_ops->handler;
                        }
                }
        }

        mutex_unlock(&hotplug_lock);

        if (!run)
                return;

        if (cb)
                cb(dd->adev->handle, event, dd->hp_context);

        dock_release_hotplug(dd);
}

static struct dock_station *find_dock_station(acpi_handle handle)
{
        struct dock_station *ds;

        list_for_each_entry(ds, &dock_stations, sibling)
                if (ds->handle == handle)
                        return ds;

        return NULL;
}

/**
 * find_dock_dependent_device - get a device dependent on this dock
 * @ds: the dock station
 * @adev: ACPI device object to find.
 *
 * iterate over the dependent device list for this dock.  If the
 * dependent device matches the handle, return.
 */
static struct dock_dependent_device *
find_dock_dependent_device(struct dock_station *ds, struct acpi_device *adev)
{
        struct dock_dependent_device *dd;

        list_for_each_entry(dd, &ds->dependent_devices, list)
                if (adev == dd->adev)
                        return dd;

        return NULL;
}

void register_dock_dependent_device(struct acpi_device *adev,
                                    acpi_handle dshandle)
{
        struct dock_station *ds = find_dock_station(dshandle);

        if (ds && !find_dock_dependent_device(ds, adev))
                add_dock_dependent_device(ds, adev);
}

/*****************************************************************************
 *                         Dock functions                                    *
 *****************************************************************************/

/**
 * is_dock_device - see if a device is on a dock station
 * @adev: ACPI device object to check.
 *
 * If this device is either the dock station itself,
 * or is a device dependent on the dock station, then it
 * is a dock device
 */
int is_dock_device(struct acpi_device *adev)
{
        struct dock_station *dock_station;

        if (!dock_station_count)
                return 0;

        if (acpi_dock_match(adev->handle))
                return 1;

        list_for_each_entry(dock_station, &dock_stations, sibling)
                if (find_dock_dependent_device(dock_station, adev))
                        return 1;

        return 0;
}
EXPORT_SYMBOL_GPL(is_dock_device);

/**
 * dock_present - see if the dock station is present.
 * @ds: the dock station
 *
 * execute the _STA method.  note that present does not
 * imply that we are docked.
 */
static int dock_present(struct dock_station *ds)
{
        unsigned long long sta;
        acpi_status status;

        if (ds) {
                status = acpi_evaluate_integer(ds->handle, "_STA", NULL, &sta);
                if (ACPI_SUCCESS(status) && sta)
                        return 1;
        }
        return 0;
}

/**
 * hot_remove_dock_devices - Remove dock station devices.
 * @ds: Dock station.
 */
static void hot_remove_dock_devices(struct dock_station *ds)
{
        struct dock_dependent_device *dd;

        /*
         * Walk the list in reverse order so that devices that have been added
         * last are removed first (in case there are some indirect dependencies
         * between them).
         */
        list_for_each_entry_reverse(dd, &ds->dependent_devices, list)
                dock_hotplug_event(dd, ACPI_NOTIFY_EJECT_REQUEST, false);

        list_for_each_entry_reverse(dd, &ds->dependent_devices, list)
                acpi_bus_trim(dd->adev);
}

/**
 * hotplug_dock_devices - Insert devices on a dock station.
 * @ds: the dock station
 * @event: either bus check or device check request
 *
 * Some devices on the dock station need to have drivers called
 * to perform hotplug operations after a dock event has occurred.
 * Traverse the list of dock devices that have registered a
 * hotplug handler, and call the handler.
 */
static void hotplug_dock_devices(struct dock_station *ds, u32 event)
{
        struct dock_dependent_device *dd;

        /* Call driver specific post-dock fixups. */
        list_for_each_entry(dd, &ds->dependent_devices, list)
                dock_hotplug_event(dd, event, DOCK_CALL_FIXUP);

        /* Call driver specific hotplug functions. */
        list_for_each_entry(dd, &ds->dependent_devices, list)
                dock_hotplug_event(dd, event, DOCK_CALL_HANDLER);

        /*
         * Check if all devices have been enumerated already.  If not, run
         * acpi_bus_scan() for them and that will cause scan handlers to be
         * attached to device objects or acpi_drivers to be stopped/started if
         * they are present.
         */
        list_for_each_entry(dd, &ds->dependent_devices, list) {
                struct acpi_device *adev = dd->adev;

                if (!acpi_device_enumerated(adev)) {
                        int ret = acpi_bus_scan(adev->handle);
                        if (ret)
                                dev_dbg(&adev->dev, "scan error %d\n", -ret);
                }
        }
}

static void dock_event(struct dock_station *ds, u32 event, int num)
{
        struct device *dev = &ds->dock_device->dev;
        char event_string[13];
        char *envp[] = { event_string, NULL };
        struct dock_dependent_device *dd;

        if (num == UNDOCK_EVENT)
                sprintf(event_string, "EVENT=undock");
        else
                sprintf(event_string, "EVENT=dock");

        /*
         * Indicate that the status of the dock station has
         * changed.
         */
        if (num == DOCK_EVENT)
                kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);

        list_for_each_entry(dd, &ds->dependent_devices, list)
                dock_hotplug_event(dd, event, DOCK_CALL_UEVENT);

        if (num != DOCK_EVENT)
                kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
}

/**
 * handle_dock - handle a dock event
 * @ds: the dock station
 * @dock: to dock, or undock - that is the question
 *
 * Execute the _DCK method in response to an acpi event
 */
static void handle_dock(struct dock_station *ds, int dock)
{
        acpi_status status;
        struct acpi_object_list arg_list;
        union acpi_object arg;
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

        acpi_handle_info(ds->handle, "%s\n", dock ? "docking" : "undocking");

        /* _DCK method has one argument */
        arg_list.count = 1;
        arg_list.pointer = &arg;
        arg.type = ACPI_TYPE_INTEGER;
        arg.integer.value = dock;
        status = acpi_evaluate_object(ds->handle, "_DCK", &arg_list, &buffer);
        if (ACPI_FAILURE(status) && status != AE_NOT_FOUND)
                acpi_handle_err(ds->handle, "Failed to execute _DCK (0x%x)\n",
                                status);

        kfree(buffer.pointer);
}

static inline void dock(struct dock_station *ds)
{
        handle_dock(ds, 1);
}

static inline void undock(struct dock_station *ds)
{
        handle_dock(ds, 0);
}

static inline void begin_dock(struct dock_station *ds)
{
        ds->flags |= DOCK_DOCKING;
}

static inline void complete_dock(struct dock_station *ds)
{
        ds->flags &= ~(DOCK_DOCKING);
        ds->last_dock_time = jiffies;
}

static inline void begin_undock(struct dock_station *ds)
{
        ds->flags |= DOCK_UNDOCKING;
}

static inline void complete_undock(struct dock_station *ds)
{
        ds->flags &= ~(DOCK_UNDOCKING);
}

/**
 * dock_in_progress - see if we are in the middle of handling a dock event
 * @ds: the dock station
 *
 * Sometimes while docking, false dock events can be sent to the driver
 * because good connections aren't made or some other reason.  Ignore these
 * if we are in the middle of doing something.
 */
static int dock_in_progress(struct dock_station *ds)
{
        if ((ds->flags & DOCK_DOCKING) ||
            time_before(jiffies, (ds->last_dock_time + HZ)))
                return 1;
        return 0;
}

/**
 * register_hotplug_dock_device - register a hotplug function
 * @handle: the handle of the device
 * @ops: handlers to call after docking
 * @context: device specific data
 * @init: Optional initialization routine to run after registration
 * @release: Optional release routine to run on unregistration
 *
 * If a driver would like to perform a hotplug operation after a dock
 * event, they can register an acpi_notifiy_handler to be called by
 * the dock driver after _DCK is executed.
 */
int register_hotplug_dock_device(acpi_handle handle,
                                 const struct acpi_dock_ops *ops, void *context,
                                 void (*init)(void *), void (*release)(void *))
{
        struct dock_dependent_device *dd;
        struct dock_station *dock_station;
        struct acpi_device *adev;
        int ret = -EINVAL;

        if (WARN_ON(!context))
                return -EINVAL;

        if (!dock_station_count)
                return -ENODEV;

        ret = acpi_bus_get_device(handle, &adev);
        if (ret)
                return ret;

        /*
         * make sure this handle is for a device dependent on the dock,
         * this would include the dock station itself
         */
        list_for_each_entry(dock_station, &dock_stations, sibling) {
                /*
                 * An ATA bay can be in a dock and itself can be ejected
                 * separately, so there are two 'dock stations' which need the
                 * ops
                 */
                dd = find_dock_dependent_device(dock_station, adev);
                if (dd && !dock_init_hotplug(dd, ops, context, init, release))
                        ret = 0;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(register_hotplug_dock_device);

/**
 * unregister_hotplug_dock_device - remove yourself from the hotplug list
 * @handle: the acpi handle of the device
 */
void unregister_hotplug_dock_device(acpi_handle handle)
{
        struct dock_dependent_device *dd;
        struct dock_station *dock_station;
        struct acpi_device *adev;

        if (!dock_station_count)
                return;

        if (acpi_bus_get_device(handle, &adev))
                return;

        list_for_each_entry(dock_station, &dock_stations, sibling) {
                dd = find_dock_dependent_device(dock_station, adev);
                if (dd)
                        dock_release_hotplug(dd);
        }
}
EXPORT_SYMBOL_GPL(unregister_hotplug_dock_device);

/**
 * handle_eject_request - handle an undock request checking for error conditions
 *
 * Check to make sure the dock device is still present, then undock and
 * hotremove all the devices that may need removing.
 */
static int handle_eject_request(struct dock_station *ds, u32 event)
{
        if (dock_in_progress(ds))
                return -EBUSY;

        /*
         * here we need to generate the undock
         * event prior to actually doing the undock
         * so that the device struct still exists.
         * Also, even send the dock event if the
         * device is not present anymore
         */
        dock_event(ds, event, UNDOCK_EVENT);

        hot_remove_dock_devices(ds);
        undock(ds);
        acpi_evaluate_lck(ds->handle, 0);
        acpi_evaluate_ej0(ds->handle);
        if (dock_present(ds)) {
                acpi_handle_err(ds->handle, "Unable to undock!\n");
                return -EBUSY;
        }
        complete_undock(ds);
        return 0;
}

/**
 * dock_notify - Handle ACPI dock notification.
 * @adev: Dock station's ACPI device object.
 * @event: Event code.
 *
 * If we are notified to dock, then check to see if the dock is
 * present and then dock.  Notify all drivers of the dock event,
 * and then hotplug and devices that may need hotplugging.
 */
int dock_notify(struct acpi_device *adev, u32 event)
{
        acpi_handle handle = adev->handle;
        struct dock_station *ds = find_dock_station(handle);
        int surprise_removal = 0;

        if (!ds)
                return -ENODEV;

        /*
         * According to acpi spec 3.0a, if a DEVICE_CHECK notification
         * is sent and _DCK is present, it is assumed to mean an undock
         * request.
         */
        if ((ds->flags & DOCK_IS_DOCK) && event == ACPI_NOTIFY_DEVICE_CHECK)
                event = ACPI_NOTIFY_EJECT_REQUEST;

        /*
         * dock station: BUS_CHECK - docked or surprise removal
         *               DEVICE_CHECK - undocked
         * other device: BUS_CHECK/DEVICE_CHECK - added or surprise removal
         *
         * To simplify event handling, dock dependent device handler always
         * get ACPI_NOTIFY_BUS_CHECK/ACPI_NOTIFY_DEVICE_CHECK for add and
         * ACPI_NOTIFY_EJECT_REQUEST for removal
         */
        switch (event) {
        case ACPI_NOTIFY_BUS_CHECK:
        case ACPI_NOTIFY_DEVICE_CHECK:
                if (!dock_in_progress(ds) && !acpi_device_enumerated(adev)) {
                        begin_dock(ds);
                        dock(ds);
                        if (!dock_present(ds)) {
                                acpi_handle_err(handle, "Unable to dock!\n");
                                complete_dock(ds);
                                break;
                        }
                        hotplug_dock_devices(ds, event);
                        complete_dock(ds);
                        dock_event(ds, event, DOCK_EVENT);
                        acpi_evaluate_lck(ds->handle, 1);
                        acpi_update_all_gpes();
                        break;
                }
                if (dock_present(ds) || dock_in_progress(ds))
                        break;
                /* This is a surprise removal */
                surprise_removal = 1;
                event = ACPI_NOTIFY_EJECT_REQUEST;
                /* Fall back */
        case ACPI_NOTIFY_EJECT_REQUEST:
                begin_undock(ds);
                if ((immediate_undock && !(ds->flags & DOCK_IS_ATA))
                   || surprise_removal)
                        handle_eject_request(ds, event);
                else
                        dock_event(ds, event, UNDOCK_EVENT);
                break;
        }
        return 0;
}

/*
 * show_docked - read method for "docked" file in sysfs
 */
static ssize_t show_docked(struct device *dev,
                           struct device_attribute *attr, char *buf)
{
        struct dock_station *dock_station = dev->platform_data;
        struct acpi_device *adev = NULL;

        acpi_bus_get_device(dock_station->handle, &adev);
        return snprintf(buf, PAGE_SIZE, "%u\n", acpi_device_enumerated(adev));
}
static DEVICE_ATTR(docked, S_IRUGO, show_docked, NULL);

/*
 * show_flags - read method for flags file in sysfs
 */
static ssize_t show_flags(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        struct dock_station *dock_station = dev->platform_data;
        return snprintf(buf, PAGE_SIZE, "%d\n", dock_station->flags);

}
static DEVICE_ATTR(flags, S_IRUGO, show_flags, NULL);

/*
 * write_undock - write method for "undock" file in sysfs
 */
static ssize_t write_undock(struct device *dev, struct device_attribute *attr,
                           const char *buf, size_t count)
{
        int ret;
        struct dock_station *dock_station = dev->platform_data;

        if (!count)
                return -EINVAL;

        acpi_scan_lock_acquire();
        begin_undock(dock_station);
        ret = handle_eject_request(dock_station, ACPI_NOTIFY_EJECT_REQUEST);
        acpi_scan_lock_release();
        return ret ? ret: count;
}
static DEVICE_ATTR(undock, S_IWUSR, NULL, write_undock);

/*
 * show_dock_uid - read method for "uid" file in sysfs
 */
static ssize_t show_dock_uid(struct device *dev,
                             struct device_attribute *attr, char *buf)
{
        unsigned long long lbuf;
        struct dock_station *dock_station = dev->platform_data;
        acpi_status status = acpi_evaluate_integer(dock_station->handle,
                                        "_UID", NULL, &lbuf);
        if (ACPI_FAILURE(status))
            return 0;

        return snprintf(buf, PAGE_SIZE, "%llx\n", lbuf);
}
static DEVICE_ATTR(uid, S_IRUGO, show_dock_uid, NULL);

static ssize_t show_dock_type(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct dock_station *dock_station = dev->platform_data;
        char *type;

        if (dock_station->flags & DOCK_IS_DOCK)
                type = "dock_station";
        else if (dock_station->flags & DOCK_IS_ATA)
                type = "ata_bay";
        else if (dock_station->flags & DOCK_IS_BAT)
                type = "battery_bay";
        else
                type = "unknown";

        return snprintf(buf, PAGE_SIZE, "%s\n", type);
}
static DEVICE_ATTR(type, S_IRUGO, show_dock_type, NULL);

static struct attribute *dock_attributes[] = {
        &dev_attr_docked.attr,
        &dev_attr_flags.attr,
        &dev_attr_undock.attr,
        &dev_attr_uid.attr,
        &dev_attr_type.attr,
        NULL
};

static struct attribute_group dock_attribute_group = {
        .attrs = dock_attributes
};

/**
 * acpi_dock_add - Add a new dock station
 * @adev: Dock station ACPI device object.
 *
 * allocated and initialize a new dock station device.
 */
void acpi_dock_add(struct acpi_device *adev)
{
        struct dock_station *dock_station, ds = { NULL, };
        acpi_handle handle = adev->handle;
        struct platform_device *dd;
        int ret;

        dd = platform_device_register_data(NULL, "dock", dock_station_count,
                                           &ds, sizeof(ds));
        if (IS_ERR(dd))
                return;

        dock_station = dd->dev.platform_data;

        dock_station->handle = handle;
        dock_station->dock_device = dd;
        dock_station->last_dock_time = jiffies - HZ;

        INIT_LIST_HEAD(&dock_station->sibling);
        INIT_LIST_HEAD(&dock_station->dependent_devices);

        /* we want the dock device to send uevents */
        dev_set_uevent_suppress(&dd->dev, 0);

        if (acpi_dock_match(handle))
                dock_station->flags |= DOCK_IS_DOCK;
        if (acpi_ata_match(handle))
                dock_station->flags |= DOCK_IS_ATA;
        if (acpi_device_is_battery(handle))
                dock_station->flags |= DOCK_IS_BAT;

        ret = sysfs_create_group(&dd->dev.kobj, &dock_attribute_group);
        if (ret)
                goto err_unregister;

        /* add the dock station as a device dependent on itself */
        ret = add_dock_dependent_device(dock_station, adev);
        if (ret)
                goto err_rmgroup;

        dock_station_count++;
        list_add(&dock_station->sibling, &dock_stations);
        adev->flags.is_dock_station = true;
        dev_info(&adev->dev, "ACPI dock station (docks/bays count: %d)\n",
                 dock_station_count);
        return;

err_rmgroup:
        remove_dock_dependent_devices(dock_station);
        sysfs_remove_group(&dd->dev.kobj, &dock_attribute_group);
err_unregister:
        platform_device_unregister(dd);
        acpi_handle_err(handle, "%s encountered error %d\n", __func__, ret);
}