asus_oled.c

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/*
 *  Asus OLED USB driver
 *
 *  Copyright (C) 2007,2008 Jakub Schmidtke ([email protected])
 *
 *  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.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 *
 *
 *  This module is based on usbled and asus-laptop modules.
 *
 *
 *  Asus OLED support is based on asusoled program taken from
 *  <http://lapsus.berlios.de/asus_oled.html>.
 *
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/platform_device.h>
#include <linux/ctype.h>

#define ASUS_OLED_VERSION       "0.04-dev"
#define ASUS_OLED_NAME          "asus-oled"
#define ASUS_OLED_UNDERSCORE_NAME   "asus_oled"

#define ASUS_OLED_STATIC        's'
#define ASUS_OLED_ROLL          'r'
#define ASUS_OLED_FLASH         'f'

#define ASUS_OLED_MAX_WIDTH     1792
#define ASUS_OLED_DISP_HEIGHT       32
#define ASUS_OLED_PACKET_BUF_SIZE   256

#define USB_VENDOR_ID_ASUS      0x0b05
#define USB_DEVICE_ID_ASUS_LCM      0x1726
#define USB_DEVICE_ID_ASUS_LCM2     0x175b

MODULE_AUTHOR("Jakub Schmidtke, [email protected]");
MODULE_DESCRIPTION("Asus OLED Driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(ASUS_OLED_VERSION);

static struct class *oled_class;
static int oled_num;

static uint start_off;

module_param(start_off, uint, 0644);

MODULE_PARM_DESC(start_off,
         "Set to 1 to switch off OLED display after it is attached");

enum oled_pack_mode {
    PACK_MODE_G1,
    PACK_MODE_G50,
    PACK_MODE_LAST
};

struct oled_dev_desc_str {
    uint16_t        idVendor;
    uint16_t        idProduct;
    /* width of display */
    uint16_t        devWidth;
    /* formula to be used while packing the picture */
    enum oled_pack_mode packMode;
    const char      *devDesc;
};

/* table of devices that work with this driver */
static const struct usb_device_id id_table[] = {
    /* Asus G1/G2 (and variants)*/
    { USB_DEVICE(USB_VENDOR_ID_ASUS, USB_DEVICE_ID_ASUS_LCM) },
    /* Asus G50V (and possibly others - G70? G71?)*/
    { USB_DEVICE(USB_VENDOR_ID_ASUS, USB_DEVICE_ID_ASUS_LCM2) },
    { },
};

/* parameters of specific devices */
static struct oled_dev_desc_str oled_dev_desc_table[] = {
    { USB_VENDOR_ID_ASUS, USB_DEVICE_ID_ASUS_LCM, 128, PACK_MODE_G1,
        "G1/G2" },
    { USB_VENDOR_ID_ASUS, USB_DEVICE_ID_ASUS_LCM2, 256, PACK_MODE_G50,
        "G50" },
    { },
};

MODULE_DEVICE_TABLE(usb, id_table);

struct asus_oled_header {
    uint8_t     magic1;
    uint8_t     magic2;
    uint8_t     flags;
    uint8_t     value3;
    uint8_t     buffer1;
    uint8_t     buffer2;
    uint8_t     value6;
    uint8_t     value7;
    uint8_t     value8;
    uint8_t     padding2[7];
} __attribute((packed));

struct asus_oled_packet {
    struct asus_oled_header     header;
    uint8_t             bitmap[ASUS_OLED_PACKET_BUF_SIZE];
} __attribute((packed));

struct asus_oled_dev {
    struct usb_device       *udev;
    uint8_t         pic_mode;
    uint16_t        dev_width;
    enum oled_pack_mode pack_mode;
    size_t          height;
    size_t          width;
    size_t          x_shift;
    size_t          y_shift;
    size_t          buf_offs;
    uint8_t         last_val;
    size_t          buf_size;
    char            *buf;
    uint8_t         enabled;
    uint8_t         enabled_post_resume;
    struct device       *dev;
};

static void setup_packet_header(struct asus_oled_packet *packet, char flags,
             char value3, char buffer1, char buffer2, char value6,
             char value7, char value8)
{
    memset(packet, 0, sizeof(struct asus_oled_header));
    packet->header.magic1 = 0x55;
    packet->header.magic2 = 0xaa;
    packet->header.flags = flags;
    packet->header.value3 = value3;
    packet->header.buffer1 = buffer1;
    packet->header.buffer2 = buffer2;
    packet->header.value6 = value6;
    packet->header.value7 = value7;
    packet->header.value8 = value8;
}

static void enable_oled(struct asus_oled_dev *odev, uint8_t enabl)
{
    int retval;
    int act_len;
    struct asus_oled_packet *packet;

    packet = kzalloc(sizeof(struct asus_oled_packet), GFP_KERNEL);

    if (!packet) {
        dev_err(&odev->udev->dev, "out of memory\n");
        return;
    }

    setup_packet_header(packet, 0x20, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00);

    if (enabl)
        packet->bitmap[0] = 0xaf;
    else
        packet->bitmap[0] = 0xae;

    retval = usb_bulk_msg(odev->udev,
        usb_sndbulkpipe(odev->udev, 2),
        packet,
        sizeof(struct asus_oled_header) + 1,
        &act_len,
        -1);

    if (retval)
        dev_dbg(&odev->udev->dev, "retval = %d\n", retval);

    odev->enabled = enabl;

    kfree(packet);
}

static ssize_t set_enabled(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t count)
{
    struct usb_interface *intf = to_usb_interface(dev);
    struct asus_oled_dev *odev = usb_get_intfdata(intf);
    unsigned long value;
    if (kstrtoul(buf, 10, &value))
        return -EINVAL;

    enable_oled(odev, value);

    return count;
}

static ssize_t class_set_enabled(struct device *device,
                 struct device_attribute *attr,
                 const char *buf, size_t count)
{
    struct asus_oled_dev *odev =
        (struct asus_oled_dev *) dev_get_drvdata(device);
    unsigned long value;

    if (kstrtoul(buf, 10, &value))
        return -EINVAL;

    enable_oled(odev, value);

    return count;
}

static ssize_t get_enabled(struct device *dev, struct device_attribute *attr,
               char *buf)
{
    struct usb_interface *intf = to_usb_interface(dev);
    struct asus_oled_dev *odev = usb_get_intfdata(intf);

    return sprintf(buf, "%d\n", odev->enabled);
}

static ssize_t class_get_enabled(struct device *device,
                 struct device_attribute *attr, char *buf)
{
    struct asus_oled_dev *odev =
        (struct asus_oled_dev *) dev_get_drvdata(device);

    return sprintf(buf, "%d\n", odev->enabled);
}

static void send_packets(struct usb_device *udev,
             struct asus_oled_packet *packet,
             char *buf, uint8_t p_type, size_t p_num)
{
    size_t i;
    int act_len;

    for (i = 0; i < p_num; i++) {
        int retval;

        switch (p_type) {
        case ASUS_OLED_ROLL:
            setup_packet_header(packet, 0x40, 0x80, p_num,
                        i + 1, 0x00, 0x01, 0xff);
            break;
        case ASUS_OLED_STATIC:
            setup_packet_header(packet, 0x10 + i, 0x80, 0x01,
                        0x01, 0x00, 0x01, 0x00);
            break;
        case ASUS_OLED_FLASH:
            setup_packet_header(packet, 0x10 + i, 0x80, 0x01,
                        0x01, 0x00, 0x00, 0xff);
            break;
        }

        memcpy(packet->bitmap, buf + (ASUS_OLED_PACKET_BUF_SIZE*i),
               ASUS_OLED_PACKET_BUF_SIZE);

        retval = usb_bulk_msg(udev, usb_sndctrlpipe(udev, 2),
                      packet, sizeof(struct asus_oled_packet),
                      &act_len, -1);

        if (retval)
            dev_dbg(&udev->dev, "retval = %d\n", retval);
    }
}

static void send_packet(struct usb_device *udev,
            struct asus_oled_packet *packet,
            size_t offset, size_t len, char *buf, uint8_t b1,
            uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5,
            uint8_t b6) {
    int retval;
    int act_len;

    setup_packet_header(packet, b1, b2, b3, b4, b5, b6, 0x00);
    memcpy(packet->bitmap, buf + offset, len);

    retval = usb_bulk_msg(udev,
                  usb_sndctrlpipe(udev, 2),
                  packet,
                  sizeof(struct asus_oled_packet),
                  &act_len,
                  -1);

    if (retval)
        dev_dbg(&udev->dev, "retval = %d\n", retval);
}


static void send_packets_g50(struct usb_device *udev,
                 struct asus_oled_packet *packet, char *buf)
{
    send_packet(udev, packet,     0, 0x100, buf,
            0x10, 0x00, 0x02, 0x01, 0x00, 0x01);
    send_packet(udev, packet, 0x100, 0x080, buf,
            0x10, 0x00, 0x02, 0x02, 0x80, 0x00);

    send_packet(udev, packet, 0x180, 0x100, buf,
            0x11, 0x00, 0x03, 0x01, 0x00, 0x01);
    send_packet(udev, packet, 0x280, 0x100, buf,
            0x11, 0x00, 0x03, 0x02, 0x00, 0x01);
    send_packet(udev, packet, 0x380, 0x080, buf,
            0x11, 0x00, 0x03, 0x03, 0x80, 0x00);
}


static void send_data(struct asus_oled_dev *odev)
{
    size_t packet_num = odev->buf_size / ASUS_OLED_PACKET_BUF_SIZE;
    struct asus_oled_packet *packet;

    packet = kzalloc(sizeof(struct asus_oled_packet), GFP_KERNEL);

    if (!packet) {
        dev_err(&odev->udev->dev, "out of memory\n");
        return;
    }

    if (odev->pack_mode == PACK_MODE_G1) {
        /* When sending roll-mode data the display updated only
           first packet.  I have no idea why, but when static picture
           is sent just before rolling picture everything works fine. */
        if (odev->pic_mode == ASUS_OLED_ROLL)
            send_packets(odev->udev, packet, odev->buf,
                     ASUS_OLED_STATIC, 2);

        /* Only ROLL mode can use more than 2 packets.*/
        if (odev->pic_mode != ASUS_OLED_ROLL && packet_num > 2)
            packet_num = 2;

        send_packets(odev->udev, packet, odev->buf,
                 odev->pic_mode, packet_num);
    } else if (odev->pack_mode == PACK_MODE_G50) {
        send_packets_g50(odev->udev, packet, odev->buf);
    }

    kfree(packet);
}

static int append_values(struct asus_oled_dev *odev, uint8_t val, size_t count)
{
    odev->last_val = val;

    if (val == 0) {
        odev->buf_offs += count;
        return 0;
    }

    while (count-- > 0) {
        size_t x = odev->buf_offs % odev->width;
        size_t y = odev->buf_offs / odev->width;
        size_t i;

        x += odev->x_shift;
        y += odev->y_shift;

        switch (odev->pack_mode) {
        case PACK_MODE_G1:
            /* i = (x/128)*640 + 127 - x + (y/8)*128;
               This one for 128 is the same, but might be better
               for different widths? */
            i = (x/odev->dev_width)*640 +
                odev->dev_width - 1 - x +
                (y/8)*odev->dev_width;
            break;

        case PACK_MODE_G50:
            i =  (odev->dev_width - 1 - x)/8 + y*odev->dev_width/8;
            break;

        default:
            i = 0;
            dev_err(odev->dev, "Unknown OLED Pack Mode: %d!\n",
                   odev->pack_mode);
            break;
        }

        if (i >= odev->buf_size) {
            dev_err(odev->dev, "Buffer overflow! Report a bug:"
                   "offs: %d >= %d i: %d (x: %d y: %d)\n",
                   (int) odev->buf_offs, (int) odev->buf_size,
                   (int) i, (int) x, (int) y);
            return -EIO;
        }

        switch (odev->pack_mode) {
        case PACK_MODE_G1:
            odev->buf[i] &= ~(1<<(y%8));
            break;

        case PACK_MODE_G50:
            odev->buf[i] &= ~(1<<(x%8));
            break;

        default:
            /* cannot get here; stops gcc complaining*/
            ;
        }

        odev->buf_offs++;
    }

    return 0;
}

static ssize_t odev_set_picture(struct asus_oled_dev *odev,
                const char *buf, size_t count)
{
    size_t offs = 0, max_offs;

    if (count < 1)
        return 0;

    if (tolower(buf[0]) == 'b') {
        /* binary mode, set the entire memory*/

        size_t i;

        odev->buf_size = (odev->dev_width * ASUS_OLED_DISP_HEIGHT) / 8;

        kfree(odev->buf);
        odev->buf = kmalloc(odev->buf_size, GFP_KERNEL);
        if (odev->buf == NULL) {
            odev->buf_size = 0;
            dev_err(odev->dev, "Out of memory!\n");
            return -ENOMEM;
        }

        memset(odev->buf, 0xff, odev->buf_size);

        for (i = 1; i < count && i <= 32 * 32; i++) {
            odev->buf[i-1] = buf[i];
            odev->buf_offs = i-1;
        }

        odev->width = odev->dev_width / 8;
        odev->height = ASUS_OLED_DISP_HEIGHT;
        odev->x_shift = 0;
        odev->y_shift = 0;
        odev->last_val =  0;

        send_data(odev);

        return count;
    }

    if (buf[0] == '<') {
        size_t i;
        size_t w = 0, h = 0;
        size_t w_mem, h_mem;

        if (count < 10 || buf[2] != ':')
            goto error_header;


        switch (tolower(buf[1])) {
        case ASUS_OLED_STATIC:
        case ASUS_OLED_ROLL:
        case ASUS_OLED_FLASH:
            odev->pic_mode = buf[1];
            break;
        default:
            dev_err(odev->dev, "Wrong picture mode: '%c'.\n",
                   buf[1]);
            return -EIO;
            break;
        }

        for (i = 3; i < count; ++i) {
            if (buf[i] >= '0' && buf[i] <= '9') {
                w = 10*w + (buf[i] - '0');

                if (w > ASUS_OLED_MAX_WIDTH)
                    goto error_width;
            } else if (tolower(buf[i]) == 'x') {
                break;
            } else {
                goto error_width;
            }
        }

        for (++i; i < count; ++i) {
            if (buf[i] >= '0' && buf[i] <= '9') {
                h = 10*h + (buf[i] - '0');

                if (h > ASUS_OLED_DISP_HEIGHT)
                    goto error_height;
            } else if (tolower(buf[i]) == '>') {
                break;
            } else {
                goto error_height;
            }
        }

        if (w < 1 || w > ASUS_OLED_MAX_WIDTH)
            goto error_width;

        if (h < 1 || h > ASUS_OLED_DISP_HEIGHT)
            goto error_height;

        if (i >= count || buf[i] != '>')
            goto error_header;

        offs = i+1;

        if (w % (odev->dev_width) != 0)
            w_mem = (w/(odev->dev_width) + 1)*(odev->dev_width);
        else
            w_mem = w;

        if (h < ASUS_OLED_DISP_HEIGHT)
            h_mem = ASUS_OLED_DISP_HEIGHT;
        else
            h_mem = h;

        odev->buf_size = w_mem * h_mem / 8;

        kfree(odev->buf);
        odev->buf = kmalloc(odev->buf_size, GFP_KERNEL);

        if (odev->buf == NULL) {
            odev->buf_size = 0;
            dev_err(odev->dev, "Out of memory!\n");
            return -ENOMEM;
        }

        memset(odev->buf, 0xff, odev->buf_size);

        odev->buf_offs = 0;
        odev->width = w;
        odev->height = h;
        odev->x_shift = 0;
        odev->y_shift = 0;
        odev->last_val = 0;

        if (odev->pic_mode == ASUS_OLED_FLASH) {
            if (h < ASUS_OLED_DISP_HEIGHT/2)
                odev->y_shift = (ASUS_OLED_DISP_HEIGHT/2 - h)/2;
        } else {
            if (h < ASUS_OLED_DISP_HEIGHT)
                odev->y_shift = (ASUS_OLED_DISP_HEIGHT - h)/2;
        }

        if (w < (odev->dev_width))
            odev->x_shift = ((odev->dev_width) - w)/2;
    }

    max_offs = odev->width * odev->height;

    while (offs < count && odev->buf_offs < max_offs) {
        int ret = 0;

        if (buf[offs] == '1' || buf[offs] == '#') {
            ret = append_values(odev, 1, 1);
            if (ret < 0)
                return ret;
        } else if (buf[offs] == '0' || buf[offs] == ' ') {
            ret = append_values(odev, 0, 1);
            if (ret < 0)
                return ret;
        } else if (buf[offs] == '\n') {
            /* New line detected. Lets assume, that all characters
               till the end of the line were equal to the last
               character in this line.*/
            if (odev->buf_offs % odev->width != 0)
                ret = append_values(odev, odev->last_val,
                            odev->width -
                            (odev->buf_offs %
                             odev->width));
            if (ret < 0)
                return ret;
        }

        offs++;
    }

    if (odev->buf_offs >= max_offs)
        send_data(odev);

    return count;

error_width:
    dev_err(odev->dev, "Wrong picture width specified.\n");
    return -EIO;

error_height:
    dev_err(odev->dev, "Wrong picture height specified.\n");
    return -EIO;

error_header:
    dev_err(odev->dev, "Wrong picture header.\n");
    return -EIO;
}

static ssize_t set_picture(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t count)
{
    struct usb_interface *intf = to_usb_interface(dev);

    return odev_set_picture(usb_get_intfdata(intf), buf, count);
}

static ssize_t class_set_picture(struct device *device,
                 struct device_attribute *attr,
                 const char *buf, size_t count)
{
    return odev_set_picture((struct asus_oled_dev *)
                dev_get_drvdata(device), buf, count);
}

#define ASUS_OLED_DEVICE_ATTR(_file)        dev_attr_asus_oled_##_file

static DEVICE_ATTR(asus_oled_enabled, S_IWUSR | S_IRUGO,
           get_enabled, set_enabled);
static DEVICE_ATTR(asus_oled_picture, S_IWUSR , NULL, set_picture);

static DEVICE_ATTR(enabled, S_IWUSR | S_IRUGO,
           class_get_enabled, class_set_enabled);
static DEVICE_ATTR(picture, S_IWUSR, NULL, class_set_picture);

static int asus_oled_probe(struct usb_interface *interface,
               const struct usb_device_id *id)
{
    struct usb_device *udev = interface_to_usbdev(interface);
    struct asus_oled_dev *odev = NULL;
    int retval = -ENOMEM;
    uint16_t dev_width = 0;
    enum oled_pack_mode pack_mode = PACK_MODE_LAST;
    const struct oled_dev_desc_str *dev_desc = oled_dev_desc_table;
    const char *desc = NULL;

    if (!id) {
        /* Even possible? Just to make sure...*/
        dev_err(&interface->dev, "No usb_device_id provided!\n");
        return -ENODEV;
    }

    for (; dev_desc->idVendor; dev_desc++) {
        if (dev_desc->idVendor == id->idVendor
            && dev_desc->idProduct == id->idProduct) {
            dev_width = dev_desc->devWidth;
            desc = dev_desc->devDesc;
            pack_mode = dev_desc->packMode;
            break;
        }
    }

    if (!desc || dev_width < 1 || pack_mode == PACK_MODE_LAST) {
        dev_err(&interface->dev,
            "Missing or incomplete device description!\n");
        return -ENODEV;
    }

    odev = kzalloc(sizeof(struct asus_oled_dev), GFP_KERNEL);

    if (odev == NULL) {
        dev_err(&interface->dev, "Out of memory\n");
        return -ENOMEM;
    }

    odev->udev = usb_get_dev(udev);
    odev->pic_mode = ASUS_OLED_STATIC;
    odev->dev_width = dev_width;
    odev->pack_mode = pack_mode;
    odev->height = 0;
    odev->width = 0;
    odev->x_shift = 0;
    odev->y_shift = 0;
    odev->buf_offs = 0;
    odev->buf_size = 0;
    odev->last_val = 0;
    odev->buf = NULL;
    odev->enabled = 1;
    odev->dev = NULL;

    usb_set_intfdata(interface, odev);

    retval = device_create_file(&interface->dev,
                    &ASUS_OLED_DEVICE_ATTR(enabled));
    if (retval)
        goto err_files;

    retval = device_create_file(&interface->dev,
                    &ASUS_OLED_DEVICE_ATTR(picture));
    if (retval)
        goto err_files;

    odev->dev = device_create(oled_class, &interface->dev, MKDEV(0, 0),
                  NULL, "oled_%d", ++oled_num);

    if (IS_ERR(odev->dev)) {
        retval = PTR_ERR(odev->dev);
        goto err_files;
    }

    dev_set_drvdata(odev->dev, odev);

    retval = device_create_file(odev->dev, &dev_attr_enabled);
    if (retval)
        goto err_class_enabled;

    retval = device_create_file(odev->dev, &dev_attr_picture);
    if (retval)
        goto err_class_picture;

    dev_info(&interface->dev,
         "Attached Asus OLED device: %s [width %u, pack_mode %d]\n",
         desc, odev->dev_width, odev->pack_mode);

    if (start_off)
        enable_oled(odev, 0);

    return 0;

err_class_picture:
    device_remove_file(odev->dev, &dev_attr_picture);

err_class_enabled:
    device_remove_file(odev->dev, &dev_attr_enabled);
    device_unregister(odev->dev);

err_files:
    device_remove_file(&interface->dev, &ASUS_OLED_DEVICE_ATTR(enabled));
    device_remove_file(&interface->dev, &ASUS_OLED_DEVICE_ATTR(picture));

    usb_set_intfdata(interface, NULL);
    usb_put_dev(odev->udev);
    kfree(odev);

    return retval;
}

static void asus_oled_disconnect(struct usb_interface *interface)
{
    struct asus_oled_dev *odev;

    odev = usb_get_intfdata(interface);
    usb_set_intfdata(interface, NULL);

    device_remove_file(odev->dev, &dev_attr_picture);
    device_remove_file(odev->dev, &dev_attr_enabled);
    device_unregister(odev->dev);

    device_remove_file(&interface->dev, &ASUS_OLED_DEVICE_ATTR(picture));
    device_remove_file(&interface->dev, &ASUS_OLED_DEVICE_ATTR(enabled));

    usb_put_dev(odev->udev);

    kfree(odev->buf);

    kfree(odev);

    dev_info(&interface->dev, "Disconnected Asus OLED device\n");
}

#ifdef CONFIG_PM
static int asus_oled_suspend(struct usb_interface *intf, pm_message_t message)
{
    struct asus_oled_dev *odev;

    odev = usb_get_intfdata(intf);
    if (!odev)
        return -ENODEV;

    odev->enabled_post_resume = odev->enabled;
    enable_oled(odev, 0);

    return 0;
}

static int asus_oled_resume(struct usb_interface *intf)
{
    struct asus_oled_dev *odev;

    odev = usb_get_intfdata(intf);
    if (!odev)
        return -ENODEV;

    enable_oled(odev, odev->enabled_post_resume);

    return 0;
}
#else
#define asus_oled_suspend NULL
#define asus_oled_resume NULL
#endif

static struct usb_driver oled_driver = {
    .name =     ASUS_OLED_NAME,
    .probe =    asus_oled_probe,
    .disconnect =   asus_oled_disconnect,
    .id_table = id_table,
    .suspend =  asus_oled_suspend,
    .resume =   asus_oled_resume,
};

static CLASS_ATTR_STRING(version, S_IRUGO,
            ASUS_OLED_UNDERSCORE_NAME " " ASUS_OLED_VERSION);

static int __init asus_oled_init(void)
{
    int retval = 0;
    oled_class = class_create(THIS_MODULE, ASUS_OLED_UNDERSCORE_NAME);

    if (IS_ERR(oled_class)) {
        pr_err("Error creating " ASUS_OLED_UNDERSCORE_NAME " class\n");
        return PTR_ERR(oled_class);
    }

    retval = class_create_file(oled_class, &class_attr_version.attr);
    if (retval) {
        pr_err("Error creating class version file\n");
        goto error;
    }

    retval = usb_register(&oled_driver);

    if (retval) {
        pr_err("usb_register failed. Error number %d\n", retval);
        goto error;
    }

    return retval;

error:
    class_destroy(oled_class);
    return retval;
}

static void __exit asus_oled_exit(void)
{
    usb_deregister(&oled_driver);
    class_remove_file(oled_class, &class_attr_version.attr);
    class_destroy(oled_class);
}

module_init(asus_oled_init);
module_exit(asus_oled_exit);