symbolserial.c

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/*
 * Symbol USB barcode to serial driver
 *
 * Copyright (C) 2009 Greg Kroah-Hartman <[email protected]>
 * 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");