usblcd.c

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/*****************************************************************************
 *                          USBLCD Kernel Driver                             *
 *                            Version 1.05                                   *
 *             (C) 2005 Georges Toth <[email protected]>                       *
 *                                                                           *
 *     This file is licensed under the GPL. See COPYING in the package.      *
 * Based on usb-skeleton.c 2.0 by Greg Kroah-Hartman ([email protected])        *
 *                                                                           *
 *                                                                           *
 * 28.02.05 Complete rewrite of the original usblcd.c driver,                *
 *          based on usb_skeleton.c.                                         *
 *          This new driver allows more than one USB-LCD to be connected     *
 *          and controlled, at once                                          *
 *****************************************************************************/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/usb.h>

#define DRIVER_VERSION "USBLCD Driver Version 1.05"

#define USBLCD_MINOR        144

#define IOCTL_GET_HARD_VERSION  1
#define IOCTL_GET_DRV_VERSION   2


static DEFINE_MUTEX(lcd_mutex);
static const struct usb_device_id id_table[] = {
    { .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
    { },
};
MODULE_DEVICE_TABLE(usb, id_table);

static DEFINE_MUTEX(open_disc_mutex);


struct usb_lcd {
    struct usb_device   *udev;          /* init: probe_lcd */
    struct usb_interface    *interface;     /* the interface for
                               this device */
    unsigned char       *bulk_in_buffer;    /* the buffer to receive
                               data */
    size_t          bulk_in_size;       /* the size of the
                               receive buffer */
    __u8            bulk_in_endpointAddr;   /* the address of the
                               bulk in endpoint */
    __u8            bulk_out_endpointAddr;  /* the address of the
                               bulk out endpoint */
    struct kref     kref;
    struct semaphore    limit_sem;      /* to stop writes at
                               full throttle from
                               using up all RAM */
    struct usb_anchor   submitted;      /* URBs to wait for
                               before suspend */
};
#define to_lcd_dev(d) container_of(d, struct usb_lcd, kref)

#define USB_LCD_CONCURRENT_WRITES   5

static struct usb_driver lcd_driver;


static void lcd_delete(struct kref *kref)
{
    struct usb_lcd *dev = to_lcd_dev(kref);

    usb_put_dev(dev->udev);
    kfree(dev->bulk_in_buffer);
    kfree(dev);
}


static int lcd_open(struct inode *inode, struct file *file)
{
    struct usb_lcd *dev;
    struct usb_interface *interface;
    int subminor, r;

    mutex_lock(&lcd_mutex);
    subminor = iminor(inode);

    interface = usb_find_interface(&lcd_driver, subminor);
    if (!interface) {
        mutex_unlock(&lcd_mutex);
        printk(KERN_ERR "USBLCD: %s - error, can't find device for minor %d\n",
               __func__, subminor);
        return -ENODEV;
    }

    mutex_lock(&open_disc_mutex);
    dev = usb_get_intfdata(interface);
    if (!dev) {
        mutex_unlock(&open_disc_mutex);
        mutex_unlock(&lcd_mutex);
        return -ENODEV;
    }

    /* increment our usage count for the device */
    kref_get(&dev->kref);
    mutex_unlock(&open_disc_mutex);

    /* grab a power reference */
    r = usb_autopm_get_interface(interface);
    if (r < 0) {
        kref_put(&dev->kref, lcd_delete);
        mutex_unlock(&lcd_mutex);
        return r;
    }

    /* save our object in the file's private structure */
    file->private_data = dev;
    mutex_unlock(&lcd_mutex);

    return 0;
}

static int lcd_release(struct inode *inode, struct file *file)
{
    struct usb_lcd *dev;

    dev = file->private_data;
    if (dev == NULL)
        return -ENODEV;

    /* decrement the count on our device */
    usb_autopm_put_interface(dev->interface);
    kref_put(&dev->kref, lcd_delete);
    return 0;
}

static ssize_t lcd_read(struct file *file, char __user * buffer,
            size_t count, loff_t *ppos)
{
    struct usb_lcd *dev;
    int retval = 0;
    int bytes_read;

    dev = file->private_data;

    /* do a blocking bulk read to get data from the device */
    retval = usb_bulk_msg(dev->udev,
                  usb_rcvbulkpipe(dev->udev,
                          dev->bulk_in_endpointAddr),
                  dev->bulk_in_buffer,
                  min(dev->bulk_in_size, count),
                  &bytes_read, 10000);

    /* if the read was successful, copy the data to userspace */
    if (!retval) {
        if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
            retval = -EFAULT;
        else
            retval = bytes_read;
    }

    return retval;
}

static long lcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    struct usb_lcd *dev;
    u16 bcdDevice;
    char buf[30];

    dev = file->private_data;
    if (dev == NULL)
        return -ENODEV;

    switch (cmd) {
    case IOCTL_GET_HARD_VERSION:
        mutex_lock(&lcd_mutex);
        bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
        sprintf(buf, "%1d%1d.%1d%1d",
            (bcdDevice & 0xF000)>>12,
            (bcdDevice & 0xF00)>>8,
            (bcdDevice & 0xF0)>>4,
            (bcdDevice & 0xF));
        mutex_unlock(&lcd_mutex);
        if (copy_to_user((void __user *)arg, buf, strlen(buf)) != 0)
            return -EFAULT;
        break;
    case IOCTL_GET_DRV_VERSION:
        sprintf(buf, DRIVER_VERSION);
        if (copy_to_user((void __user *)arg, buf, strlen(buf)) != 0)
            return -EFAULT;
        break;
    default:
        return -ENOTTY;
        break;
    }

    return 0;
}

static void lcd_write_bulk_callback(struct urb *urb)
{
    struct usb_lcd *dev;
    int status = urb->status;

    dev = urb->context;

    /* sync/async unlink faults aren't errors */
    if (status &&
        !(status == -ENOENT ||
          status == -ECONNRESET ||
          status == -ESHUTDOWN)) {
        dev_dbg(&dev->interface->dev,
            "nonzero write bulk status received: %d\n", status);
    }

    /* free up our allocated buffer */
    usb_free_coherent(urb->dev, urb->transfer_buffer_length,
              urb->transfer_buffer, urb->transfer_dma);
    up(&dev->limit_sem);
}

static ssize_t lcd_write(struct file *file, const char __user * user_buffer,
             size_t count, loff_t *ppos)
{
    struct usb_lcd *dev;
    int retval = 0, r;
    struct urb *urb = NULL;
    char *buf = NULL;

    dev = file->private_data;

    /* verify that we actually have some data to write */
    if (count == 0)
        goto exit;

    r = down_interruptible(&dev->limit_sem);
    if (r < 0)
        return -EINTR;

    /* create a urb, and a buffer for it, and copy the data to the urb */
    urb = usb_alloc_urb(0, GFP_KERNEL);
    if (!urb) {
        retval = -ENOMEM;
        goto err_no_buf;
    }

    buf = usb_alloc_coherent(dev->udev, count, GFP_KERNEL,
                 &urb->transfer_dma);
    if (!buf) {
        retval = -ENOMEM;
        goto error;
    }

    if (copy_from_user(buf, user_buffer, count)) {
        retval = -EFAULT;
        goto error;
    }

    /* initialize the urb properly */
    usb_fill_bulk_urb(urb, dev->udev,
              usb_sndbulkpipe(dev->udev,
              dev->bulk_out_endpointAddr),
              buf, count, lcd_write_bulk_callback, dev);
    urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

    usb_anchor_urb(urb, &dev->submitted);

    /* send the data out the bulk port */
    retval = usb_submit_urb(urb, GFP_KERNEL);
    if (retval) {
        dev_err(&dev->udev->dev,
            "%s - failed submitting write urb, error %d\n",
            __func__, retval);
        goto error_unanchor;
    }

    /* release our reference to this urb,
       the USB core will eventually free it entirely */
    usb_free_urb(urb);

exit:
    return count;
error_unanchor:
    usb_unanchor_urb(urb);
error:
    usb_free_coherent(dev->udev, count, buf, urb->transfer_dma);
    usb_free_urb(urb);
err_no_buf:
    up(&dev->limit_sem);
    return retval;
}

static const struct file_operations lcd_fops = {
    .owner =        THIS_MODULE,
    .read =         lcd_read,
    .write =        lcd_write,
    .open =         lcd_open,
    .unlocked_ioctl = lcd_ioctl,
    .release =      lcd_release,
    .llseek =    noop_llseek,
};

/*
 * usb class driver info in order to get a minor number from the usb core,
 * and to have the device registered with the driver core
 */
static struct usb_class_driver lcd_class = {
    .name =         "lcd%d",
    .fops =         &lcd_fops,
    .minor_base =   USBLCD_MINOR,
};

static int lcd_probe(struct usb_interface *interface,
             const struct usb_device_id *id)
{
    struct usb_lcd *dev = NULL;
    struct usb_host_interface *iface_desc;
    struct usb_endpoint_descriptor *endpoint;
    size_t buffer_size;
    int i;
    int retval = -ENOMEM;

    /* allocate memory for our device state and initialize it */
    dev = kzalloc(sizeof(*dev), GFP_KERNEL);
    if (dev == NULL) {
        dev_err(&interface->dev, "Out of memory\n");
        goto error;
    }
    kref_init(&dev->kref);
    sema_init(&dev->limit_sem, USB_LCD_CONCURRENT_WRITES);
    init_usb_anchor(&dev->submitted);

    dev->udev = usb_get_dev(interface_to_usbdev(interface));
    dev->interface = interface;

    if (le16_to_cpu(dev->udev->descriptor.idProduct) != 0x0001) {
        dev_warn(&interface->dev, "USBLCD model not supported.\n");
        retval = -ENODEV;
        goto error;
    }

    /* set up the endpoint information */
    /* use only the first bulk-in and bulk-out endpoints */
    iface_desc = interface->cur_altsetting;
    for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
        endpoint = &iface_desc->endpoint[i].desc;

        if (!dev->bulk_in_endpointAddr &&
            usb_endpoint_is_bulk_in(endpoint)) {
            /* we found a bulk in endpoint */
            buffer_size = usb_endpoint_maxp(endpoint);
            dev->bulk_in_size = buffer_size;
            dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
            dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
            if (!dev->bulk_in_buffer) {
                dev_err(&interface->dev,
                    "Could not allocate bulk_in_buffer\n");
                goto error;
            }
        }

        if (!dev->bulk_out_endpointAddr &&
            usb_endpoint_is_bulk_out(endpoint)) {
            /* we found a bulk out endpoint */
            dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
        }
    }
    if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
        dev_err(&interface->dev,
            "Could not find both bulk-in and bulk-out endpoints\n");
        goto error;
    }

    /* save our data pointer in this interface device */
    usb_set_intfdata(interface, dev);

    /* we can register the device now, as it is ready */
    retval = usb_register_dev(interface, &lcd_class);
    if (retval) {
        /* something prevented us from registering this driver */
        dev_err(&interface->dev,
            "Not able to get a minor for this device.\n");
        usb_set_intfdata(interface, NULL);
        goto error;
    }

    i = le16_to_cpu(dev->udev->descriptor.bcdDevice);

    dev_info(&interface->dev, "USBLCD Version %1d%1d.%1d%1d found "
         "at address %d\n", (i & 0xF000)>>12, (i & 0xF00)>>8,
         (i & 0xF0)>>4, (i & 0xF), dev->udev->devnum);

    /* let the user know what node this device is now attached to */
    dev_info(&interface->dev, "USB LCD device now attached to USBLCD-%d\n",
         interface->minor);
    return 0;

error:
    if (dev)
        kref_put(&dev->kref, lcd_delete);
    return retval;
}

static void lcd_draw_down(struct usb_lcd *dev)
{
    int time;

    time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
    if (!time)
        usb_kill_anchored_urbs(&dev->submitted);
}

static int lcd_suspend(struct usb_interface *intf, pm_message_t message)
{
    struct usb_lcd *dev = usb_get_intfdata(intf);

    if (!dev)
        return 0;
    lcd_draw_down(dev);
    return 0;
}

static int lcd_resume(struct usb_interface *intf)
{
    return 0;
}

static void lcd_disconnect(struct usb_interface *interface)
{
    struct usb_lcd *dev;
    int minor = interface->minor;

    mutex_lock(&open_disc_mutex);
    dev = usb_get_intfdata(interface);
    usb_set_intfdata(interface, NULL);
    mutex_unlock(&open_disc_mutex);

    /* give back our minor */
    usb_deregister_dev(interface, &lcd_class);

    /* decrement our usage count */
    kref_put(&dev->kref, lcd_delete);

    dev_info(&interface->dev, "USB LCD #%d now disconnected\n", minor);
}

static struct usb_driver lcd_driver = {
    .name =     "usblcd",
    .probe =    lcd_probe,
    .disconnect =   lcd_disconnect,
    .suspend =  lcd_suspend,
    .resume =   lcd_resume,
    .id_table = id_table,
    .supports_autosuspend = 1,
};

module_usb_driver(lcd_driver);

MODULE_AUTHOR("Georges Toth <[email protected]>");
MODULE_DESCRIPTION(DRIVER_VERSION);
MODULE_LICENSE("GPL");