/*****************************************************************************
 *                          USBLCD Kernel Driver                             *
 *                            Version 1.05                                   *
 *             (C) 2005 Georges Toth <g.toth@e-biz.lu>                       *
 *                                                                           *
 *     This file is licensed under the GPL. See COPYING in the package.      *
 * Based on usb-skeleton.c 2.0 by Greg Kroah-Hartman (greg@kroah.com)        *
 *                                                                           *
 *                                                                           *
 * 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);
                err("USBLCD: %s - error, can't find device for minor %d",
                     __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)) {
                dbg("USBLCD: %s - nonzero write bulk status received: %d",
                    __func__, 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) {
                err("USBLCD: %s - failed submitting write urb, error %d",
                    __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) {
                err("Out of memory");
                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) {
                                err("Could not allocate bulk_in_buffer");
                                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)) {
                err("Could not find both bulk-in and bulk-out endpoints");
                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 */
                err("Not able to get a minor for this device.");
                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,
};

static int __init usb_lcd_init(void)
{
        int result;

        result = usb_register(&lcd_driver);
        if (result)
                err("usb_register failed. Error number %d", result);

        return result;
}


static void __exit usb_lcd_exit(void)
{
        usb_deregister(&lcd_driver);
}

module_init(usb_lcd_init);
module_exit(usb_lcd_exit);

MODULE_AUTHOR("Georges Toth <g.toth@e-biz.lu>");
MODULE_DESCRIPTION(DRIVER_VERSION);
MODULE_LICENSE("GPL");