// SPDX-License-Identifier: GPL-2.0+
/*
 * Provides user-space access to the SSAM EC via the /dev/surface/aggregator
 * misc device. Intended for debugging and development.
 *
 * Copyright (C) 2020-2022 Maximilian Luz <luzmaximilian@gmail.com>
 */

#include <linux/fs.h>
#include <linux/ioctl.h>
#include <linux/kernel.h>
#include <linux/kfifo.h>
#include <linux/kref.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>

#include <linux/surface_aggregator/cdev.h>
#include <linux/surface_aggregator/controller.h>
#include <linux/surface_aggregator/serial_hub.h>

#define SSAM_CDEV_DEVICE_NAME   "surface_aggregator_cdev"


/* -- Main structures. ------------------------------------------------------ */

enum ssam_cdev_device_state {
        SSAM_CDEV_DEVICE_SHUTDOWN_BIT = BIT(0),
};

struct ssam_cdev {
        struct kref kref;
        struct rw_semaphore lock;

        struct device *dev;
        struct ssam_controller *ctrl;
        struct miscdevice mdev;
        unsigned long flags;

        struct rw_semaphore client_lock;  /* Guards client list. */
        struct list_head client_list;
};

struct ssam_cdev_client;

struct ssam_cdev_notifier {
        struct ssam_cdev_client *client;
        struct ssam_event_notifier nf;
};

struct ssam_cdev_client {
        struct ssam_cdev *cdev;
        struct list_head node;

        struct mutex notifier_lock;     /* Guards notifier access for registration */
        struct ssam_cdev_notifier *notifier[SSH_NUM_EVENTS];

        struct mutex read_lock;         /* Guards FIFO buffer read access */
        struct mutex write_lock;        /* Guards FIFO buffer write access */
        DECLARE_KFIFO(buffer, u8, 4096);

        wait_queue_head_t waitq;
        struct fasync_struct *fasync;
};

static void __ssam_cdev_release(struct kref *kref)
{
        kfree(container_of(kref, struct ssam_cdev, kref));
}

static struct ssam_cdev *ssam_cdev_get(struct ssam_cdev *cdev)
{
        if (cdev)
                kref_get(&cdev->kref);

        return cdev;
}

static void ssam_cdev_put(struct ssam_cdev *cdev)
{
        if (cdev)
                kref_put(&cdev->kref, __ssam_cdev_release);
}


/* -- Notifier handling. ---------------------------------------------------- */

static u32 ssam_cdev_notifier(struct ssam_event_notifier *nf, const struct ssam_event *in)
{
        struct ssam_cdev_notifier *cdev_nf = container_of(nf, struct ssam_cdev_notifier, nf);
        struct ssam_cdev_client *client = cdev_nf->client;
        struct ssam_cdev_event event;
        size_t n = struct_size(&event, data, in->length);

        /* Translate event. */
        event.target_category = in->target_category;
        event.target_id = in->target_id;
        event.command_id = in->command_id;
        event.instance_id = in->instance_id;
        event.length = in->length;

        mutex_lock(&client->write_lock);

        /* Make sure we have enough space. */
        if (kfifo_avail(&client->buffer) < n) {
                dev_warn(client->cdev->dev,
                         "buffer full, dropping event (tc: %#04x, tid: %#04x, cid: %#04x, iid: %#04x)\n",
                         in->target_category, in->target_id, in->command_id, in->instance_id);
                mutex_unlock(&client->write_lock);
                return 0;
        }

        /* Copy event header and payload. */
        kfifo_in(&client->buffer, (const u8 *)&event, struct_size(&event, data, 0));
        kfifo_in(&client->buffer, &in->data[0], in->length);

        mutex_unlock(&client->write_lock);

        /* Notify waiting readers. */
        kill_fasync(&client->fasync, SIGIO, POLL_IN);
        wake_up_interruptible(&client->waitq);

        /*
         * Don't mark events as handled, this is the job of a proper driver and
         * not the debugging interface.
         */
        return 0;
}

static int ssam_cdev_notifier_register(struct ssam_cdev_client *client, u8 tc, int priority)
{
        const u16 rqid = ssh_tc_to_rqid(tc);
        const u16 event = ssh_rqid_to_event(rqid);
        struct ssam_cdev_notifier *nf;
        int status;

        lockdep_assert_held_read(&client->cdev->lock);

        /* Validate notifier target category. */
        if (!ssh_rqid_is_event(rqid))
                return -EINVAL;

        mutex_lock(&client->notifier_lock);

        /* Check if the notifier has already been registered. */
        if (client->notifier[event]) {
                mutex_unlock(&client->notifier_lock);
                return -EEXIST;
        }

        /* Allocate new notifier. */
        nf = kzalloc_obj(*nf);
        if (!nf) {
                mutex_unlock(&client->notifier_lock);
                return -ENOMEM;
        }

        /*
         * Create a dummy notifier with the minimal required fields for
         * observer registration. Note that we can skip fully specifying event
         * and registry here as we do not need any matching and use silent
         * registration, which does not enable the corresponding event.
         */
        nf->client = client;
        nf->nf.base.fn = ssam_cdev_notifier;
        nf->nf.base.priority = priority;
        nf->nf.event.id.target_category = tc;
        nf->nf.event.mask = 0;  /* Do not do any matching. */
        nf->nf.flags = SSAM_EVENT_NOTIFIER_OBSERVER;

        /* Register notifier. */
        status = ssam_notifier_register(client->cdev->ctrl, &nf->nf);
        if (status)
                kfree(nf);
        else
                client->notifier[event] = nf;

        mutex_unlock(&client->notifier_lock);
        return status;
}

static int ssam_cdev_notifier_unregister(struct ssam_cdev_client *client, u8 tc)
{
        const u16 rqid = ssh_tc_to_rqid(tc);
        const u16 event = ssh_rqid_to_event(rqid);
        int status;

        lockdep_assert_held_read(&client->cdev->lock);

        /* Validate notifier target category. */
        if (!ssh_rqid_is_event(rqid))
                return -EINVAL;

        mutex_lock(&client->notifier_lock);

        /* Check if the notifier is currently registered. */
        if (!client->notifier[event]) {
                mutex_unlock(&client->notifier_lock);
                return -ENOENT;
        }

        /* Unregister and free notifier. */
        status = ssam_notifier_unregister(client->cdev->ctrl, &client->notifier[event]->nf);
        kfree(client->notifier[event]);
        client->notifier[event] = NULL;

        mutex_unlock(&client->notifier_lock);
        return status;
}

static void ssam_cdev_notifier_unregister_all(struct ssam_cdev_client *client)
{
        int i;

        down_read(&client->cdev->lock);

        /*
         * This function may be used during shutdown, thus we need to test for
         * cdev->ctrl instead of the SSAM_CDEV_DEVICE_SHUTDOWN_BIT bit.
         */
        if (client->cdev->ctrl) {
                for (i = 0; i < SSH_NUM_EVENTS; i++)
                        ssam_cdev_notifier_unregister(client, i + 1);

        } else {
                int count = 0;

                /*
                 * Device has been shut down. Any notifier remaining is a bug,
                 * so warn about that as this would otherwise hardly be
                 * noticeable. Nevertheless, free them as well.
                 */
                mutex_lock(&client->notifier_lock);
                for (i = 0; i < SSH_NUM_EVENTS; i++) {
                        count += !!(client->notifier[i]);
                        kfree(client->notifier[i]);
                        client->notifier[i] = NULL;
                }
                mutex_unlock(&client->notifier_lock);

                WARN_ON(count > 0);
        }

        up_read(&client->cdev->lock);
}


/* -- IOCTL functions. ------------------------------------------------------ */

static long ssam_cdev_request(struct ssam_cdev_client *client, struct ssam_cdev_request __user *r)
{
        struct ssam_cdev_request rqst;
        struct ssam_request spec = {};
        struct ssam_response rsp = {};
        const void __user *plddata;
        void __user *rspdata;
        int status = 0, ret = 0, tmp;

        lockdep_assert_held_read(&client->cdev->lock);

        ret = copy_struct_from_user(&rqst, sizeof(rqst), r, sizeof(*r));
        if (ret)
                goto out;

        plddata = u64_to_user_ptr(rqst.payload.data);
        rspdata = u64_to_user_ptr(rqst.response.data);

        /* Setup basic request fields. */
        spec.target_category = rqst.target_category;
        spec.target_id = rqst.target_id;
        spec.command_id = rqst.command_id;
        spec.instance_id = rqst.instance_id;
        spec.flags = 0;
        spec.length = rqst.payload.length;
        spec.payload = NULL;

        if (rqst.flags & SSAM_CDEV_REQUEST_HAS_RESPONSE)
                spec.flags |= SSAM_REQUEST_HAS_RESPONSE;

        if (rqst.flags & SSAM_CDEV_REQUEST_UNSEQUENCED)
                spec.flags |= SSAM_REQUEST_UNSEQUENCED;

        rsp.capacity = rqst.response.length;
        rsp.length = 0;
        rsp.pointer = NULL;

        /* Get request payload from user-space. */
        if (spec.length) {
                if (!plddata) {
                        ret = -EINVAL;
                        goto out;
                }

                /*
                 * Note: spec.length is limited to U16_MAX bytes via struct
                 * ssam_cdev_request. This is slightly larger than the
                 * theoretical maximum (SSH_COMMAND_MAX_PAYLOAD_SIZE) of the
                 * underlying protocol (note that nothing remotely this size
                 * should ever be allocated in any normal case). This size is
                 * validated later in ssam_request_do_sync(), for allocation
                 * the bound imposed by u16 should be enough.
                 */
                spec.payload = kzalloc(spec.length, GFP_KERNEL);
                if (!spec.payload) {
                        ret = -ENOMEM;
                        goto out;
                }

                if (copy_from_user((void *)spec.payload, plddata, spec.length)) {
                        ret = -EFAULT;
                        goto out;
                }
        }

        /* Allocate response buffer. */
        if (rsp.capacity) {
                if (!rspdata) {
                        ret = -EINVAL;
                        goto out;
                }

                /*
                 * Note: rsp.capacity is limited to U16_MAX bytes via struct
                 * ssam_cdev_request. This is slightly larger than the
                 * theoretical maximum (SSH_COMMAND_MAX_PAYLOAD_SIZE) of the
                 * underlying protocol (note that nothing remotely this size
                 * should ever be allocated in any normal case). In later use,
                 * this capacity does not have to be strictly bounded, as it
                 * is only used as an output buffer to be written to. For
                 * allocation the bound imposed by u16 should be enough.
                 */
                rsp.pointer = kzalloc(rsp.capacity, GFP_KERNEL);
                if (!rsp.pointer) {
                        ret = -ENOMEM;
                        goto out;
                }
        }

        /* Perform request. */
        status = ssam_request_do_sync(client->cdev->ctrl, &spec, &rsp);
        if (status)
                goto out;

        /* Copy response to user-space. */
        if (rsp.length && copy_to_user(rspdata, rsp.pointer, rsp.length))
                ret = -EFAULT;

out:
        /* Always try to set response-length and status. */
        tmp = put_user(rsp.length, &r->response.length);
        if (tmp)
                ret = tmp;

        tmp = put_user(status, &r->status);
        if (tmp)
                ret = tmp;

        /* Cleanup. */
        kfree(spec.payload);
        kfree(rsp.pointer);

        return ret;
}

static long ssam_cdev_notif_register(struct ssam_cdev_client *client,
                                     const struct ssam_cdev_notifier_desc __user *d)
{
        struct ssam_cdev_notifier_desc desc;
        long ret;

        lockdep_assert_held_read(&client->cdev->lock);

        ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
        if (ret)
                return ret;

        return ssam_cdev_notifier_register(client, desc.target_category, desc.priority);
}

static long ssam_cdev_notif_unregister(struct ssam_cdev_client *client,
                                       const struct ssam_cdev_notifier_desc __user *d)
{
        struct ssam_cdev_notifier_desc desc;
        long ret;

        lockdep_assert_held_read(&client->cdev->lock);

        ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
        if (ret)
                return ret;

        return ssam_cdev_notifier_unregister(client, desc.target_category);
}

static long ssam_cdev_event_enable(struct ssam_cdev_client *client,
                                   const struct ssam_cdev_event_desc __user *d)
{
        struct ssam_cdev_event_desc desc;
        struct ssam_event_registry reg;
        struct ssam_event_id id;
        long ret;

        lockdep_assert_held_read(&client->cdev->lock);

        /* Read descriptor from user-space. */
        ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
        if (ret)
                return ret;

        /* Translate descriptor. */
        reg.target_category = desc.reg.target_category;
        reg.target_id = desc.reg.target_id;
        reg.cid_enable = desc.reg.cid_enable;
        reg.cid_disable = desc.reg.cid_disable;

        id.target_category = desc.id.target_category;
        id.instance = desc.id.instance;

        /* Disable event. */
        return ssam_controller_event_enable(client->cdev->ctrl, reg, id, desc.flags);
}

static long ssam_cdev_event_disable(struct ssam_cdev_client *client,
                                    const struct ssam_cdev_event_desc __user *d)
{
        struct ssam_cdev_event_desc desc;
        struct ssam_event_registry reg;
        struct ssam_event_id id;
        long ret;

        lockdep_assert_held_read(&client->cdev->lock);

        /* Read descriptor from user-space. */
        ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
        if (ret)
                return ret;

        /* Translate descriptor. */
        reg.target_category = desc.reg.target_category;
        reg.target_id = desc.reg.target_id;
        reg.cid_enable = desc.reg.cid_enable;
        reg.cid_disable = desc.reg.cid_disable;

        id.target_category = desc.id.target_category;
        id.instance = desc.id.instance;

        /* Disable event. */
        return ssam_controller_event_disable(client->cdev->ctrl, reg, id, desc.flags);
}


/* -- File operations. ------------------------------------------------------ */

static int ssam_cdev_device_open(struct inode *inode, struct file *filp)
{
        struct miscdevice *mdev = filp->private_data;
        struct ssam_cdev_client *client;
        struct ssam_cdev *cdev = container_of(mdev, struct ssam_cdev, mdev);

        /* Initialize client */
        client = vzalloc(sizeof(*client));
        if (!client)
                return -ENOMEM;

        client->cdev = ssam_cdev_get(cdev);

        INIT_LIST_HEAD(&client->node);

        mutex_init(&client->notifier_lock);

        mutex_init(&client->read_lock);
        mutex_init(&client->write_lock);
        INIT_KFIFO(client->buffer);
        init_waitqueue_head(&client->waitq);

        filp->private_data = client;

        /* Attach client. */
        down_write(&cdev->client_lock);

        if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
                up_write(&cdev->client_lock);
                mutex_destroy(&client->write_lock);
                mutex_destroy(&client->read_lock);
                mutex_destroy(&client->notifier_lock);
                ssam_cdev_put(client->cdev);
                vfree(client);
                return -ENODEV;
        }
        list_add_tail(&client->node, &cdev->client_list);

        up_write(&cdev->client_lock);

        stream_open(inode, filp);
        return 0;
}

static int ssam_cdev_device_release(struct inode *inode, struct file *filp)
{
        struct ssam_cdev_client *client = filp->private_data;

        /* Force-unregister all remaining notifiers of this client. */
        ssam_cdev_notifier_unregister_all(client);

        /* Detach client. */
        down_write(&client->cdev->client_lock);
        list_del(&client->node);
        up_write(&client->cdev->client_lock);

        /* Free client. */
        mutex_destroy(&client->write_lock);
        mutex_destroy(&client->read_lock);

        mutex_destroy(&client->notifier_lock);

        ssam_cdev_put(client->cdev);
        vfree(client);

        return 0;
}

static long __ssam_cdev_device_ioctl(struct ssam_cdev_client *client, unsigned int cmd,
                                     unsigned long arg)
{
        lockdep_assert_held_read(&client->cdev->lock);

        switch (cmd) {
        case SSAM_CDEV_REQUEST:
                return ssam_cdev_request(client, (struct ssam_cdev_request __user *)arg);

        case SSAM_CDEV_NOTIF_REGISTER:
                return ssam_cdev_notif_register(client,
                                                (struct ssam_cdev_notifier_desc __user *)arg);

        case SSAM_CDEV_NOTIF_UNREGISTER:
                return ssam_cdev_notif_unregister(client,
                                                  (struct ssam_cdev_notifier_desc __user *)arg);

        case SSAM_CDEV_EVENT_ENABLE:
                return ssam_cdev_event_enable(client, (struct ssam_cdev_event_desc __user *)arg);

        case SSAM_CDEV_EVENT_DISABLE:
                return ssam_cdev_event_disable(client, (struct ssam_cdev_event_desc __user *)arg);

        default:
                return -ENOTTY;
        }
}

static long ssam_cdev_device_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        struct ssam_cdev_client *client = file->private_data;
        long status;

        /* Ensure that controller is valid for as long as we need it. */
        if (down_read_killable(&client->cdev->lock))
                return -ERESTARTSYS;

        if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &client->cdev->flags)) {
                up_read(&client->cdev->lock);
                return -ENODEV;
        }

        status = __ssam_cdev_device_ioctl(client, cmd, arg);

        up_read(&client->cdev->lock);
        return status;
}

static ssize_t ssam_cdev_read(struct file *file, char __user *buf, size_t count, loff_t *offs)
{
        struct ssam_cdev_client *client = file->private_data;
        struct ssam_cdev *cdev = client->cdev;
        unsigned int copied;
        int status = 0;

        if (down_read_killable(&cdev->lock))
                return -ERESTARTSYS;

        /* Make sure we're not shut down. */
        if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
                up_read(&cdev->lock);
                return -ENODEV;
        }

        do {
                /* Check availability, wait if necessary. */
                if (kfifo_is_empty(&client->buffer)) {
                        up_read(&cdev->lock);

                        if (file->f_flags & O_NONBLOCK)
                                return -EAGAIN;

                        status = wait_event_interruptible(client->waitq,
                                                          !kfifo_is_empty(&client->buffer) ||
                                                          test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT,
                                                                   &cdev->flags));
                        if (status < 0)
                                return status;

                        if (down_read_killable(&cdev->lock))
                                return -ERESTARTSYS;

                        /* Need to check that we're not shut down again. */
                        if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
                                up_read(&cdev->lock);
                                return -ENODEV;
                        }
                }

                /* Try to read from FIFO. */
                if (mutex_lock_interruptible(&client->read_lock)) {
                        up_read(&cdev->lock);
                        return -ERESTARTSYS;
                }

                status = kfifo_to_user(&client->buffer, buf, count, &copied);
                mutex_unlock(&client->read_lock);

                if (status < 0) {
                        up_read(&cdev->lock);
                        return status;
                }

                /* We might not have gotten anything, check this here. */
                if (copied == 0 && (file->f_flags & O_NONBLOCK)) {
                        up_read(&cdev->lock);
                        return -EAGAIN;
                }
        } while (copied == 0);

        up_read(&cdev->lock);
        return copied;
}

static __poll_t ssam_cdev_poll(struct file *file, struct poll_table_struct *pt)
{
        struct ssam_cdev_client *client = file->private_data;
        __poll_t events = 0;

        if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &client->cdev->flags))
                return EPOLLHUP | EPOLLERR;

        poll_wait(file, &client->waitq, pt);

        if (!kfifo_is_empty(&client->buffer))
                events |= EPOLLIN | EPOLLRDNORM;

        return events;
}

static int ssam_cdev_fasync(int fd, struct file *file, int on)
{
        struct ssam_cdev_client *client = file->private_data;

        return fasync_helper(fd, file, on, &client->fasync);
}

static const struct file_operations ssam_controller_fops = {
        .owner          = THIS_MODULE,
        .open           = ssam_cdev_device_open,
        .release        = ssam_cdev_device_release,
        .read           = ssam_cdev_read,
        .poll           = ssam_cdev_poll,
        .fasync         = ssam_cdev_fasync,
        .unlocked_ioctl = ssam_cdev_device_ioctl,
        .compat_ioctl   = ssam_cdev_device_ioctl,
};


/* -- Device and driver setup ----------------------------------------------- */

static int ssam_dbg_device_probe(struct platform_device *pdev)
{
        struct ssam_controller *ctrl;
        struct ssam_cdev *cdev;
        int status;

        ctrl = ssam_client_bind(&pdev->dev);
        if (IS_ERR(ctrl))
                return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);

        cdev = kzalloc_obj(*cdev);
        if (!cdev)
                return -ENOMEM;

        kref_init(&cdev->kref);
        init_rwsem(&cdev->lock);
        cdev->ctrl = ctrl;
        cdev->dev = &pdev->dev;

        cdev->mdev.parent   = &pdev->dev;
        cdev->mdev.minor    = MISC_DYNAMIC_MINOR;
        cdev->mdev.name     = "surface_aggregator";
        cdev->mdev.nodename = "surface/aggregator";
        cdev->mdev.fops     = &ssam_controller_fops;

        init_rwsem(&cdev->client_lock);
        INIT_LIST_HEAD(&cdev->client_list);

        status = misc_register(&cdev->mdev);
        if (status) {
                kfree(cdev);
                return status;
        }

        platform_set_drvdata(pdev, cdev);
        return 0;
}

static void ssam_dbg_device_remove(struct platform_device *pdev)
{
        struct ssam_cdev *cdev = platform_get_drvdata(pdev);
        struct ssam_cdev_client *client;

        /*
         * Mark device as shut-down. Prevent new clients from being added and
         * new operations from being executed.
         */
        set_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags);

        down_write(&cdev->client_lock);

        /* Remove all notifiers registered by us. */
        list_for_each_entry(client, &cdev->client_list, node) {
                ssam_cdev_notifier_unregister_all(client);
        }

        /* Wake up async clients. */
        list_for_each_entry(client, &cdev->client_list, node) {
                kill_fasync(&client->fasync, SIGIO, POLL_HUP);
        }

        /* Wake up blocking clients. */
        list_for_each_entry(client, &cdev->client_list, node) {
                wake_up_interruptible(&client->waitq);
        }

        up_write(&cdev->client_lock);

        /*
         * The controller is only guaranteed to be valid for as long as the
         * driver is bound. Remove controller so that any lingering open files
         * cannot access it any more after we're gone.
         */
        down_write(&cdev->lock);
        cdev->ctrl = NULL;
        cdev->dev = NULL;
        up_write(&cdev->lock);

        misc_deregister(&cdev->mdev);

        ssam_cdev_put(cdev);
}

static struct platform_device *ssam_cdev_device;

static struct platform_driver ssam_cdev_driver = {
        .probe = ssam_dbg_device_probe,
        .remove = ssam_dbg_device_remove,
        .driver = {
                .name = SSAM_CDEV_DEVICE_NAME,
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
};

static int __init ssam_debug_init(void)
{
        int status;

        ssam_cdev_device = platform_device_alloc(SSAM_CDEV_DEVICE_NAME,
                                                 PLATFORM_DEVID_NONE);
        if (!ssam_cdev_device)
                return -ENOMEM;

        status = platform_device_add(ssam_cdev_device);
        if (status)
                goto err_device;

        status = platform_driver_register(&ssam_cdev_driver);
        if (status)
                goto err_driver;

        return 0;

err_driver:
        platform_device_del(ssam_cdev_device);
err_device:
        platform_device_put(ssam_cdev_device);
        return status;
}
module_init(ssam_debug_init);

static void __exit ssam_debug_exit(void)
{
        platform_driver_unregister(&ssam_cdev_driver);
        platform_device_unregister(ssam_cdev_device);
}
module_exit(ssam_debug_exit);

MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
MODULE_DESCRIPTION("User-space interface for Surface System Aggregator Module");
MODULE_LICENSE("GPL");