/*
 * Symbol USB barcode to serial driver
 *
 * Copyright (C) 2009 Greg Kroah-Hartman <gregkh@suse.de>
 * Copyright (C) 2009 Novell Inc.
 *
 *      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.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/tty.h>
#include <linux/slab.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/uaccess.h>

static const struct usb_device_id id_table[] = {
        { USB_DEVICE(0x05e0, 0x0600) },
        { },
};
MODULE_DEVICE_TABLE(usb, id_table);

/* This structure holds all of the individual device information */
struct symbol_private {
        struct usb_device *udev;
        struct usb_serial *serial;
        struct usb_serial_port *port;
        unsigned char *int_buffer;
        struct urb *int_urb;
        int buffer_size;
        u8 bInterval;
        u8 int_address;
        spinlock_t lock;        /* protects the following flags */
        bool throttled;
        bool actually_throttled;
        bool rts;
};

static void symbol_int_callback(struct urb *urb)
{
        struct symbol_private *priv = urb->context;
        unsigned char *data = urb->transfer_buffer;
        struct usb_serial_port *port = priv->port;
        int status = urb->status;
        struct tty_struct *tty;
        int result;
        int data_length;

        switch (status) {
        case 0:
                /* success */
                break;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                /* this urb is terminated, clean up */
                dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
                        __func__, status);
                return;
        default:
                dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
                        __func__, status);
                goto exit;
        }

        usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);

        if (urb->actual_length > 1) {
                data_length = urb->actual_length - 1;

                /*
                 * Data from the device comes with a 1 byte header:
                 *
                 * <size of data>data...
                 *      This is real data to be sent to the tty layer
                 * we pretty much just ignore the size and send everything
                 * else to the tty layer.
                 */
                tty = tty_port_tty_get(&port->port);
                if (tty) {
                        tty_insert_flip_string(tty, &data[1], data_length);
                        tty_flip_buffer_push(tty);
                        tty_kref_put(tty);
                }
        } else {
                dev_dbg(&priv->udev->dev,
                        "Improper amount of data received from the device, "
                        "%d bytes", urb->actual_length);
        }

exit:
        spin_lock(&priv->lock);

        /* Continue trying to always read if we should */
        if (!priv->throttled) {
                usb_fill_int_urb(priv->int_urb, priv->udev,
                                 usb_rcvintpipe(priv->udev,
                                                priv->int_address),
                                 priv->int_buffer, priv->buffer_size,
                                 symbol_int_callback, priv, priv->bInterval);
                result = usb_submit_urb(priv->int_urb, GFP_ATOMIC);
                if (result)
                        dev_err(&port->dev,
                            "%s - failed resubmitting read urb, error %d\n",
                                                        __func__, result);
        } else
                priv->actually_throttled = true;
        spin_unlock(&priv->lock);
}

static int symbol_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct symbol_private *priv = usb_get_serial_data(port->serial);
        unsigned long flags;
        int result = 0;

        spin_lock_irqsave(&priv->lock, flags);
        priv->throttled = false;
        priv->actually_throttled = false;
        priv->port = port;
        spin_unlock_irqrestore(&priv->lock, flags);

        /* Start reading from the device */
        usb_fill_int_urb(priv->int_urb, priv->udev,
                         usb_rcvintpipe(priv->udev, priv->int_address),
                         priv->int_buffer, priv->buffer_size,
                         symbol_int_callback, priv, priv->bInterval);
        result = usb_submit_urb(priv->int_urb, GFP_KERNEL);
        if (result)
                dev_err(&port->dev,
                        "%s - failed resubmitting read urb, error %d\n",
                        __func__, result);
        return result;
}

static void symbol_close(struct usb_serial_port *port)
{
        struct symbol_private *priv = usb_get_serial_data(port->serial);

        /* shutdown our urbs */
        usb_kill_urb(priv->int_urb);
}

static void symbol_throttle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct symbol_private *priv = usb_get_serial_data(port->serial);

        spin_lock_irq(&priv->lock);
        priv->throttled = true;
        spin_unlock_irq(&priv->lock);
}

static void symbol_unthrottle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct symbol_private *priv = usb_get_serial_data(port->serial);
        int result;
        bool was_throttled;

        spin_lock_irq(&priv->lock);
        priv->throttled = false;
        was_throttled = priv->actually_throttled;
        priv->actually_throttled = false;
        spin_unlock_irq(&priv->lock);

        if (was_throttled) {
                result = usb_submit_urb(priv->int_urb, GFP_KERNEL);
                if (result)
                        dev_err(&port->dev,
                                "%s - failed submitting read urb, error %d\n",
                                                        __func__, result);
        }
}

static int symbol_startup(struct usb_serial *serial)
{
        struct symbol_private *priv;
        struct usb_host_interface *intf;
        int i;
        int retval = -ENOMEM;
        bool int_in_found = false;

        /* create our private serial structure */
        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (priv == NULL) {
                dev_err(&serial->dev->dev, "%s - Out of memory\n", __func__);
                return -ENOMEM;
        }
        spin_lock_init(&priv->lock);
        priv->serial = serial;
        priv->port = serial->port[0];
        priv->udev = serial->dev;

        /* find our interrupt endpoint */
        intf = serial->interface->altsetting;
        for (i = 0; i < intf->desc.bNumEndpoints; ++i) {
                struct usb_endpoint_descriptor *endpoint;

                endpoint = &intf->endpoint[i].desc;
                if (!usb_endpoint_is_int_in(endpoint))
                        continue;

                priv->int_urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!priv->int_urb) {
                        dev_err(&priv->udev->dev, "out of memory\n");
                        goto error;
                }

                priv->buffer_size = usb_endpoint_maxp(endpoint) * 2;
                priv->int_buffer = kmalloc(priv->buffer_size, GFP_KERNEL);
                if (!priv->int_buffer) {
                        dev_err(&priv->udev->dev, "out of memory\n");
                        goto error;
                }

                priv->int_address = endpoint->bEndpointAddress;
                priv->bInterval = endpoint->bInterval;

                /* set up our int urb */
                usb_fill_int_urb(priv->int_urb, priv->udev,
                                 usb_rcvintpipe(priv->udev,
                                                endpoint->bEndpointAddress),
                                 priv->int_buffer, priv->buffer_size,
                                 symbol_int_callback, priv, priv->bInterval);

                int_in_found = true;
                break;
                }

        if (!int_in_found) {
                dev_err(&priv->udev->dev,
                        "Error - the proper endpoints were not found!\n");
                goto error;
        }

        usb_set_serial_data(serial, priv);
        return 0;

error:
        usb_free_urb(priv->int_urb);
        kfree(priv->int_buffer);
        kfree(priv);
        return retval;
}

static void symbol_disconnect(struct usb_serial *serial)
{
        struct symbol_private *priv = usb_get_serial_data(serial);

        usb_kill_urb(priv->int_urb);
        usb_free_urb(priv->int_urb);
}

static void symbol_release(struct usb_serial *serial)
{
        struct symbol_private *priv = usb_get_serial_data(serial);

        kfree(priv->int_buffer);
        kfree(priv);
}

static struct usb_serial_driver symbol_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "symbol",
        },
        .id_table =             id_table,
        .num_ports =            1,
        .attach =               symbol_startup,
        .open =                 symbol_open,
        .close =                symbol_close,
        .disconnect =           symbol_disconnect,
        .release =              symbol_release,
        .throttle =             symbol_throttle,
        .unthrottle =           symbol_unthrottle,
};

static struct usb_serial_driver * const serial_drivers[] = {
        &symbol_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);

MODULE_LICENSE("GPL");