hsi_char.c

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/*
 * HSI character device driver, implements the character device
 * interface.
 *
 * Copyright (C) 2010 Nokia Corporation. All rights reserved.
 *
 * Contact: Andras Domokos <[email protected]>
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/atomic.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/kmemleak.h>
#include <linux/ioctl.h>
#include <linux/wait.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/uaccess.h>
#include <linux/scatterlist.h>
#include <linux/stat.h>
#include <linux/hsi/hsi.h>
#include <linux/hsi/hsi_char.h>

#define HSC_DEVS        16 /* Num of channels */
#define HSC_MSGS        4

#define HSC_RXBREAK     0

#define HSC_ID_BITS     6
#define HSC_PORT_ID_BITS    4
#define HSC_ID_MASK     3
#define HSC_PORT_ID_MASK    3
#define HSC_CH_MASK     0xf

/*
 * We support up to 4 controllers that can have up to 4
 * ports, which should currently be more than enough.
 */
#define HSC_BASEMINOR(id, port_id) \
        ((((id) & HSC_ID_MASK) << HSC_ID_BITS) | \
        (((port_id) & HSC_PORT_ID_MASK) << HSC_PORT_ID_BITS))

enum {
    HSC_CH_OPEN,
    HSC_CH_READ,
    HSC_CH_WRITE,
    HSC_CH_WLINE,
};

enum {
    HSC_RX,
    HSC_TX,
};

struct hsc_client_data;
struct hsc_channel {
    unsigned int        ch;
    unsigned long       flags;
    struct list_head    free_msgs_list;
    struct list_head    rx_msgs_queue;
    struct list_head    tx_msgs_queue;
    spinlock_t      lock;
    struct hsi_client   *cl;
    struct hsc_client_data *cl_data;
    wait_queue_head_t   rx_wait;
    wait_queue_head_t   tx_wait;
};

struct hsc_client_data {
    struct cdev     cdev;
    struct mutex        lock;
    unsigned long       flags;
    unsigned int        usecnt;
    struct hsi_client   *cl;
    struct hsc_channel  channels[HSC_DEVS];
};

/* Stores the major number dynamically allocated for hsi_char */
static unsigned int hsc_major;
/* Maximum buffer size that hsi_char will accept from userspace */
static unsigned int max_data_size = 0x1000;
module_param(max_data_size, uint, 0);
MODULE_PARM_DESC(max_data_size, "max read/write data size [4,8..65536] (^2)");

static void hsc_add_tail(struct hsc_channel *channel, struct hsi_msg *msg,
                            struct list_head *queue)
{
    unsigned long flags;

    spin_lock_irqsave(&channel->lock, flags);
    list_add_tail(&msg->link, queue);
    spin_unlock_irqrestore(&channel->lock, flags);
}

static struct hsi_msg *hsc_get_first_msg(struct hsc_channel *channel,
                            struct list_head *queue)
{
    struct hsi_msg *msg = NULL;
    unsigned long flags;

    spin_lock_irqsave(&channel->lock, flags);

    if (list_empty(queue))
        goto out;

    msg = list_first_entry(queue, struct hsi_msg, link);
    list_del(&msg->link);
out:
    spin_unlock_irqrestore(&channel->lock, flags);

    return msg;
}

static inline void hsc_msg_free(struct hsi_msg *msg)
{
    kfree(sg_virt(msg->sgt.sgl));
    hsi_free_msg(msg);
}

static void hsc_free_list(struct list_head *list)
{
    struct hsi_msg *msg, *tmp;

    list_for_each_entry_safe(msg, tmp, list, link) {
        list_del(&msg->link);
        hsc_msg_free(msg);
    }
}

static void hsc_reset_list(struct hsc_channel *channel, struct list_head *l)
{
    unsigned long flags;
    LIST_HEAD(list);

    spin_lock_irqsave(&channel->lock, flags);
    list_splice_init(l, &list);
    spin_unlock_irqrestore(&channel->lock, flags);

    hsc_free_list(&list);
}

static inline struct hsi_msg *hsc_msg_alloc(unsigned int alloc_size)
{
    struct hsi_msg *msg;
    void *buf;

    msg = hsi_alloc_msg(1, GFP_KERNEL);
    if (!msg)
        goto out;
    buf = kmalloc(alloc_size, GFP_KERNEL);
    if (!buf) {
        hsi_free_msg(msg);
        goto out;
    }
    sg_init_one(msg->sgt.sgl, buf, alloc_size);
    /* Ignore false positive, due to sg pointer handling */
    kmemleak_ignore(buf);

    return msg;
out:
    return NULL;
}

static inline int hsc_msgs_alloc(struct hsc_channel *channel)
{
    struct hsi_msg *msg;
    int i;

    for (i = 0; i < HSC_MSGS; i++) {
        msg = hsc_msg_alloc(max_data_size);
        if (!msg)
            goto out;
        msg->channel = channel->ch;
        list_add_tail(&msg->link, &channel->free_msgs_list);
    }

    return 0;
out:
    hsc_free_list(&channel->free_msgs_list);

    return -ENOMEM;
}

static inline unsigned int hsc_msg_len_get(struct hsi_msg *msg)
{
    return msg->sgt.sgl->length;
}

static inline void hsc_msg_len_set(struct hsi_msg *msg, unsigned int len)
{
    msg->sgt.sgl->length = len;
}

static void hsc_rx_completed(struct hsi_msg *msg)
{
    struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
    struct hsc_channel *channel = cl_data->channels + msg->channel;

    if (test_bit(HSC_CH_READ, &channel->flags)) {
        hsc_add_tail(channel, msg, &channel->rx_msgs_queue);
        wake_up(&channel->rx_wait);
    } else {
        hsc_add_tail(channel, msg, &channel->free_msgs_list);
    }
}

static void hsc_rx_msg_destructor(struct hsi_msg *msg)
{
    msg->status = HSI_STATUS_ERROR;
    hsc_msg_len_set(msg, 0);
    hsc_rx_completed(msg);
}

static void hsc_tx_completed(struct hsi_msg *msg)
{
    struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
    struct hsc_channel *channel = cl_data->channels + msg->channel;

    if (test_bit(HSC_CH_WRITE, &channel->flags)) {
        hsc_add_tail(channel, msg, &channel->tx_msgs_queue);
        wake_up(&channel->tx_wait);
    } else {
        hsc_add_tail(channel, msg, &channel->free_msgs_list);
    }
}

static void hsc_tx_msg_destructor(struct hsi_msg *msg)
{
    msg->status = HSI_STATUS_ERROR;
    hsc_msg_len_set(msg, 0);
    hsc_tx_completed(msg);
}

static void hsc_break_req_destructor(struct hsi_msg *msg)
{
    struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);

    hsi_free_msg(msg);
    clear_bit(HSC_RXBREAK, &cl_data->flags);
}

static void hsc_break_received(struct hsi_msg *msg)
{
    struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
    struct hsc_channel *channel = cl_data->channels;
    int i, ret;

    /* Broadcast HWBREAK on all channels */
    for (i = 0; i < HSC_DEVS; i++, channel++) {
        struct hsi_msg *msg2;

        if (!test_bit(HSC_CH_READ, &channel->flags))
            continue;
        msg2 = hsc_get_first_msg(channel, &channel->free_msgs_list);
        if (!msg2)
            continue;
        clear_bit(HSC_CH_READ, &channel->flags);
        hsc_msg_len_set(msg2, 0);
        msg2->status = HSI_STATUS_COMPLETED;
        hsc_add_tail(channel, msg2, &channel->rx_msgs_queue);
        wake_up(&channel->rx_wait);
    }
    hsi_flush(msg->cl);
    ret = hsi_async_read(msg->cl, msg);
    if (ret < 0)
        hsc_break_req_destructor(msg);
}

static int hsc_break_request(struct hsi_client *cl)
{
    struct hsc_client_data *cl_data = hsi_client_drvdata(cl);
    struct hsi_msg *msg;
    int ret;

    if (test_and_set_bit(HSC_RXBREAK, &cl_data->flags))
        return -EBUSY;

    msg = hsi_alloc_msg(0, GFP_KERNEL);
    if (!msg) {
        clear_bit(HSC_RXBREAK, &cl_data->flags);
        return -ENOMEM;
    }
    msg->break_frame = 1;
    msg->complete = hsc_break_received;
    msg->destructor = hsc_break_req_destructor;
    ret = hsi_async_read(cl, msg);
    if (ret < 0)
        hsc_break_req_destructor(msg);

    return ret;
}

static int hsc_break_send(struct hsi_client *cl)
{
    struct hsi_msg *msg;
    int ret;

    msg = hsi_alloc_msg(0, GFP_ATOMIC);
    if (!msg)
        return -ENOMEM;
    msg->break_frame = 1;
    msg->complete = hsi_free_msg;
    msg->destructor = hsi_free_msg;
    ret = hsi_async_write(cl, msg);
    if (ret < 0)
        hsi_free_msg(msg);

    return ret;
}

static int hsc_rx_set(struct hsi_client *cl, struct hsc_rx_config *rxc)
{
    struct hsi_config tmp;
    int ret;

    if ((rxc->mode != HSI_MODE_STREAM) && (rxc->mode != HSI_MODE_FRAME))
        return -EINVAL;
    if ((rxc->channels == 0) || (rxc->channels > HSC_DEVS))
        return -EINVAL;
    if (rxc->channels & (rxc->channels - 1))
        return -EINVAL;
    if ((rxc->flow != HSI_FLOW_SYNC) && (rxc->flow != HSI_FLOW_PIPE))
        return -EINVAL;
    tmp = cl->rx_cfg;
    cl->rx_cfg.mode = rxc->mode;
    cl->rx_cfg.channels = rxc->channels;
    cl->rx_cfg.flow = rxc->flow;
    ret = hsi_setup(cl);
    if (ret < 0) {
        cl->rx_cfg = tmp;
        return ret;
    }
    if (rxc->mode == HSI_MODE_FRAME)
        hsc_break_request(cl);

    return ret;
}

static inline void hsc_rx_get(struct hsi_client *cl, struct hsc_rx_config *rxc)
{
    rxc->mode = cl->rx_cfg.mode;
    rxc->channels = cl->rx_cfg.channels;
    rxc->flow = cl->rx_cfg.flow;
}

static int hsc_tx_set(struct hsi_client *cl, struct hsc_tx_config *txc)
{
    struct hsi_config tmp;
    int ret;

    if ((txc->mode != HSI_MODE_STREAM) && (txc->mode != HSI_MODE_FRAME))
        return -EINVAL;
    if ((txc->channels == 0) || (txc->channels > HSC_DEVS))
        return -EINVAL;
    if (txc->channels & (txc->channels - 1))
        return -EINVAL;
    if ((txc->arb_mode != HSI_ARB_RR) && (txc->arb_mode != HSI_ARB_PRIO))
        return -EINVAL;
    tmp = cl->tx_cfg;
    cl->tx_cfg.mode = txc->mode;
    cl->tx_cfg.channels = txc->channels;
    cl->tx_cfg.speed = txc->speed;
    cl->tx_cfg.arb_mode = txc->arb_mode;
    ret = hsi_setup(cl);
    if (ret < 0) {
        cl->tx_cfg = tmp;
        return ret;
    }

    return ret;
}

static inline void hsc_tx_get(struct hsi_client *cl, struct hsc_tx_config *txc)
{
    txc->mode = cl->tx_cfg.mode;
    txc->channels = cl->tx_cfg.channels;
    txc->speed = cl->tx_cfg.speed;
    txc->arb_mode = cl->tx_cfg.arb_mode;
}

static ssize_t hsc_read(struct file *file, char __user *buf, size_t len,
                        loff_t *ppos __maybe_unused)
{
    struct hsc_channel *channel = file->private_data;
    struct hsi_msg *msg;
    ssize_t ret;

    if (len == 0)
        return 0;
    if (!IS_ALIGNED(len, sizeof(u32)))
        return -EINVAL;
    if (len > max_data_size)
        len = max_data_size;
    if (channel->ch >= channel->cl->rx_cfg.channels)
        return -ECHRNG;
    if (test_and_set_bit(HSC_CH_READ, &channel->flags))
        return -EBUSY;
    msg = hsc_get_first_msg(channel, &channel->free_msgs_list);
    if (!msg) {
        ret = -ENOSPC;
        goto out;
    }
    hsc_msg_len_set(msg, len);
    msg->complete = hsc_rx_completed;
    msg->destructor = hsc_rx_msg_destructor;
    ret = hsi_async_read(channel->cl, msg);
    if (ret < 0) {
        hsc_add_tail(channel, msg, &channel->free_msgs_list);
        goto out;
    }

    ret = wait_event_interruptible(channel->rx_wait,
                    !list_empty(&channel->rx_msgs_queue));
    if (ret < 0) {
        clear_bit(HSC_CH_READ, &channel->flags);
        hsi_flush(channel->cl);
        return -EINTR;
    }

    msg = hsc_get_first_msg(channel, &channel->rx_msgs_queue);
    if (msg) {
        if (msg->status != HSI_STATUS_ERROR) {
            ret = copy_to_user((void __user *)buf,
            sg_virt(msg->sgt.sgl), hsc_msg_len_get(msg));
            if (ret)
                ret = -EFAULT;
            else
                ret = hsc_msg_len_get(msg);
        } else {
            ret = -EIO;
        }
        hsc_add_tail(channel, msg, &channel->free_msgs_list);
    }
out:
    clear_bit(HSC_CH_READ, &channel->flags);

    return ret;
}

static ssize_t hsc_write(struct file *file, const char __user *buf, size_t len,
                        loff_t *ppos __maybe_unused)
{
    struct hsc_channel *channel = file->private_data;
    struct hsi_msg *msg;
    ssize_t ret;

    if ((len == 0) || !IS_ALIGNED(len, sizeof(u32)))
        return -EINVAL;
    if (len > max_data_size)
        len = max_data_size;
    if (channel->ch >= channel->cl->tx_cfg.channels)
        return -ECHRNG;
    if (test_and_set_bit(HSC_CH_WRITE, &channel->flags))
        return -EBUSY;
    msg = hsc_get_first_msg(channel, &channel->free_msgs_list);
    if (!msg) {
        clear_bit(HSC_CH_WRITE, &channel->flags);
        return -ENOSPC;
    }
    if (copy_from_user(sg_virt(msg->sgt.sgl), (void __user *)buf, len)) {
        ret = -EFAULT;
        goto out;
    }
    hsc_msg_len_set(msg, len);
    msg->complete = hsc_tx_completed;
    msg->destructor = hsc_tx_msg_destructor;
    ret = hsi_async_write(channel->cl, msg);
    if (ret < 0)
        goto out;

    ret = wait_event_interruptible(channel->tx_wait,
                    !list_empty(&channel->tx_msgs_queue));
    if (ret < 0) {
        clear_bit(HSC_CH_WRITE, &channel->flags);
        hsi_flush(channel->cl);
        return -EINTR;
    }

    msg = hsc_get_first_msg(channel, &channel->tx_msgs_queue);
    if (msg) {
        if (msg->status == HSI_STATUS_ERROR)
            ret = -EIO;
        else
            ret = hsc_msg_len_get(msg);

        hsc_add_tail(channel, msg, &channel->free_msgs_list);
    }
out:
    clear_bit(HSC_CH_WRITE, &channel->flags);

    return ret;
}

static long hsc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    struct hsc_channel *channel = file->private_data;
    unsigned int state;
    struct hsc_rx_config rxc;
    struct hsc_tx_config txc;
    long ret = 0;

    switch (cmd) {
    case HSC_RESET:
        hsi_flush(channel->cl);
        break;
    case HSC_SET_PM:
        if (copy_from_user(&state, (void __user *)arg, sizeof(state)))
            return -EFAULT;
        if (state == HSC_PM_DISABLE) {
            if (test_and_set_bit(HSC_CH_WLINE, &channel->flags))
                return -EINVAL;
            ret = hsi_start_tx(channel->cl);
        } else if (state == HSC_PM_ENABLE) {
            if (!test_and_clear_bit(HSC_CH_WLINE, &channel->flags))
                return -EINVAL;
            ret = hsi_stop_tx(channel->cl);
        } else {
            ret = -EINVAL;
        }
        break;
    case HSC_SEND_BREAK:
        return hsc_break_send(channel->cl);
    case HSC_SET_RX:
        if (copy_from_user(&rxc, (void __user *)arg, sizeof(rxc)))
            return -EFAULT;
        return hsc_rx_set(channel->cl, &rxc);
    case HSC_GET_RX:
        hsc_rx_get(channel->cl, &rxc);
        if (copy_to_user((void __user *)arg, &rxc, sizeof(rxc)))
            return -EFAULT;
        break;
    case HSC_SET_TX:
        if (copy_from_user(&txc, (void __user *)arg, sizeof(txc)))
            return -EFAULT;
        return hsc_tx_set(channel->cl, &txc);
    case HSC_GET_TX:
        hsc_tx_get(channel->cl, &txc);
        if (copy_to_user((void __user *)arg, &txc, sizeof(txc)))
            return -EFAULT;
        break;
    default:
        return -ENOIOCTLCMD;
    }

    return ret;
}

static inline void __hsc_port_release(struct hsc_client_data *cl_data)
{
    BUG_ON(cl_data->usecnt == 0);

    if (--cl_data->usecnt == 0) {
        hsi_flush(cl_data->cl);
        hsi_release_port(cl_data->cl);
    }
}

static int hsc_open(struct inode *inode, struct file *file)
{
    struct hsc_client_data *cl_data;
    struct hsc_channel *channel;
    int ret = 0;

    pr_debug("open, minor = %d\n", iminor(inode));

    cl_data = container_of(inode->i_cdev, struct hsc_client_data, cdev);
    mutex_lock(&cl_data->lock);
    channel = cl_data->channels + (iminor(inode) & HSC_CH_MASK);

    if (test_and_set_bit(HSC_CH_OPEN, &channel->flags)) {
        ret = -EBUSY;
        goto out;
    }
    /*
     * Check if we have already claimed the port associated to the HSI
     * client. If not then try to claim it, else increase its refcount
     */
    if (cl_data->usecnt == 0) {
        ret = hsi_claim_port(cl_data->cl, 0);
        if (ret < 0)
            goto out;
        hsi_setup(cl_data->cl);
    }
    cl_data->usecnt++;

    ret = hsc_msgs_alloc(channel);
    if (ret < 0) {
        __hsc_port_release(cl_data);
        goto out;
    }

    file->private_data = channel;
    mutex_unlock(&cl_data->lock);

    return ret;
out:
    mutex_unlock(&cl_data->lock);

    return ret;
}

static int hsc_release(struct inode *inode __maybe_unused, struct file *file)
{
    struct hsc_channel *channel = file->private_data;
    struct hsc_client_data *cl_data = channel->cl_data;

    mutex_lock(&cl_data->lock);
    file->private_data = NULL;
    if (test_and_clear_bit(HSC_CH_WLINE, &channel->flags))
        hsi_stop_tx(channel->cl);
    __hsc_port_release(cl_data);
    hsc_reset_list(channel, &channel->rx_msgs_queue);
    hsc_reset_list(channel, &channel->tx_msgs_queue);
    hsc_reset_list(channel, &channel->free_msgs_list);
    clear_bit(HSC_CH_READ, &channel->flags);
    clear_bit(HSC_CH_WRITE, &channel->flags);
    clear_bit(HSC_CH_OPEN, &channel->flags);
    wake_up(&channel->rx_wait);
    wake_up(&channel->tx_wait);
    mutex_unlock(&cl_data->lock);

    return 0;
}

static const struct file_operations hsc_fops = {
    .owner      = THIS_MODULE,
    .read       = hsc_read,
    .write      = hsc_write,
    .unlocked_ioctl = hsc_ioctl,
    .open       = hsc_open,
    .release    = hsc_release,
};

static void __devinit hsc_channel_init(struct hsc_channel *channel)
{
    init_waitqueue_head(&channel->rx_wait);
    init_waitqueue_head(&channel->tx_wait);
    spin_lock_init(&channel->lock);
    INIT_LIST_HEAD(&channel->free_msgs_list);
    INIT_LIST_HEAD(&channel->rx_msgs_queue);
    INIT_LIST_HEAD(&channel->tx_msgs_queue);
}

static int __devinit hsc_probe(struct device *dev)
{
    const char devname[] = "hsi_char";
    struct hsc_client_data *cl_data;
    struct hsc_channel *channel;
    struct hsi_client *cl = to_hsi_client(dev);
    unsigned int hsc_baseminor;
    dev_t hsc_dev;
    int ret;
    int i;

    cl_data = kzalloc(sizeof(*cl_data), GFP_KERNEL);
    if (!cl_data) {
        dev_err(dev, "Could not allocate hsc_client_data\n");
        return -ENOMEM;
    }
    hsc_baseminor = HSC_BASEMINOR(hsi_id(cl), hsi_port_id(cl));
    if (!hsc_major) {
        ret = alloc_chrdev_region(&hsc_dev, hsc_baseminor,
                        HSC_DEVS, devname);
        if (ret > 0)
            hsc_major = MAJOR(hsc_dev);
    } else {
        hsc_dev = MKDEV(hsc_major, hsc_baseminor);
        ret = register_chrdev_region(hsc_dev, HSC_DEVS, devname);
    }
    if (ret < 0) {
        dev_err(dev, "Device %s allocation failed %d\n",
                    hsc_major ? "minor" : "major", ret);
        goto out1;
    }
    mutex_init(&cl_data->lock);
    hsi_client_set_drvdata(cl, cl_data);
    cdev_init(&cl_data->cdev, &hsc_fops);
    cl_data->cdev.owner = THIS_MODULE;
    cl_data->cl = cl;
    for (i = 0, channel = cl_data->channels; i < HSC_DEVS; i++, channel++) {
        hsc_channel_init(channel);
        channel->ch = i;
        channel->cl = cl;
        channel->cl_data = cl_data;
    }

    /* 1 hsi client -> N char devices (one for each channel) */
    ret = cdev_add(&cl_data->cdev, hsc_dev, HSC_DEVS);
    if (ret) {
        dev_err(dev, "Could not add char device %d\n", ret);
        goto out2;
    }

    return 0;
out2:
    unregister_chrdev_region(hsc_dev, HSC_DEVS);
out1:
    kfree(cl_data);

    return ret;
}

static int __devexit hsc_remove(struct device *dev)
{
    struct hsi_client *cl = to_hsi_client(dev);
    struct hsc_client_data *cl_data = hsi_client_drvdata(cl);
    dev_t hsc_dev = cl_data->cdev.dev;

    cdev_del(&cl_data->cdev);
    unregister_chrdev_region(hsc_dev, HSC_DEVS);
    hsi_client_set_drvdata(cl, NULL);
    kfree(cl_data);

    return 0;
}

static struct hsi_client_driver hsc_driver = {
    .driver = {
        .name   = "hsi_char",
        .owner  = THIS_MODULE,
        .probe  = hsc_probe,
        .remove = __devexit_p(hsc_remove),
    },
};

static int __init hsc_init(void)
{
    int ret;

    if ((max_data_size < 4) || (max_data_size > 0x10000) ||
        (max_data_size & (max_data_size - 1))) {
        pr_err("Invalid max read/write data size");
        return -EINVAL;
    }

    ret = hsi_register_client_driver(&hsc_driver);
    if (ret) {
        pr_err("Error while registering HSI/SSI driver %d", ret);
        return ret;
    }

    pr_info("HSI/SSI char device loaded\n");

    return 0;
}
module_init(hsc_init);

static void __exit hsc_exit(void)
{
    hsi_unregister_client_driver(&hsc_driver);
    pr_info("HSI char device removed\n");
}
module_exit(hsc_exit);

MODULE_AUTHOR("Andras Domokos <[email protected]>");
MODULE_ALIAS("hsi:hsi_char");
MODULE_DESCRIPTION("HSI character device");
MODULE_LICENSE("GPL v2");