// SPDX-License-Identifier: GPL-2.0-only
/*
 * HSI character device driver, implements the character device
 * interface.
 *
 * Copyright (C) 2010 Nokia Corporation. All rights reserved.
 *
 * Contact: Andras Domokos <andras.domokos@nokia.com>
 */

#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 - hsi_char internal channel data
 * @ch: channel number
 * @flags: Keeps state of the channel (open/close, reading, writing)
 * @free_msgs_list: List of free HSI messages/requests
 * @rx_msgs_queue: List of pending RX requests
 * @tx_msgs_queue: List of pending TX requests
 * @lock: Serialize access to the lists
 * @cl: reference to the associated hsi_client
 * @cl_data: reference to the client data that this channels belongs to
 * @rx_wait: RX requests wait queue
 * @tx_wait: TX requests wait queue
 */
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 - hsi_char internal client data
 * @cdev: Characther device associated to the hsi_client
 * @lock: Lock to serialize open/close access
 * @flags: Keeps track of port state (rx hwbreak armed)
 * @usecnt: Use count for claiming the HSI port (mutex protected)
 * @cl: Referece to the HSI client
 * @channels: Array of channels accessible by the client
 */
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.num_hw_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.num_hw_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.num_hw_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.num_hw_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.num_hw_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.num_hw_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 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 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_obj(*cl_data);
        if (!cl_data)
                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 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 = 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\n");
                return -EINVAL;
        }

        ret = hsi_register_client_driver(&hsc_driver);
        if (ret) {
                pr_err("Error while registering HSI/SSI driver %d\n", 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 <andras.domokos@nokia.com>");
MODULE_ALIAS("hsi:hsi_char");
MODULE_DESCRIPTION("HSI character device");
MODULE_LICENSE("GPL v2");