opticon.c

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/*
 * Opticon USB barcode to serial driver
 *
 * Copyright (C) 2011 Martin Jansen <[email protected]>
 * Copyright (C) 2008 - 2009 Greg Kroah-Hartman <[email protected]>
 * Copyright (C) 2008 - 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/tty_driver.h>
#include <linux/slab.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/uaccess.h>

#define CONTROL_RTS         0x02
#define RESEND_CTS_STATE    0x03

/* max number of write urbs in flight */
#define URB_UPPER_LIMIT 8

/* This driver works for the Opticon 1D barcode reader
 * an examples of 1D barcode types are EAN, UPC, Code39, IATA etc.. */
#define DRIVER_DESC "Opticon USB barcode to serial driver (1D)"

static const struct usb_device_id id_table[] = {
    { USB_DEVICE(0x065a, 0x0009) },
    { },
};
MODULE_DEVICE_TABLE(usb, id_table);

/* This structure holds all of the individual device information */
struct opticon_private {
    struct usb_device *udev;
    struct usb_serial *serial;
    struct usb_serial_port *port;
    unsigned char *bulk_in_buffer;
    struct urb *bulk_read_urb;
    int buffer_size;
    u8 bulk_address;
    spinlock_t lock;    /* protects the following flags */
    bool throttled;
    bool actually_throttled;
    bool rts;
    bool cts;
    int outstanding_urbs;
};



static void opticon_read_bulk_callback(struct urb *urb)
{
    struct opticon_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;
    unsigned long flags;

    switch (status) {
    case 0:
        /* success */
        break;
    case -ECONNRESET:
    case -ENOENT:
    case -ESHUTDOWN:
        /* this urb is terminated, clean up */
        dev_dbg(&priv->udev->dev, "%s - urb shutting down with status: %d\n",
            __func__, status);
        return;
    default:
        dev_dbg(&priv->udev->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 > 2) {
        data_length = urb->actual_length - 2;

        /*
         * Data from the device comes with a 2 byte header:
         *
         * <0x00><0x00>data...
         *  This is real data to be sent to the tty layer
         * <0x00><0x01)level
         *  This is a CTS level change, the third byte is the CTS
         *  value (0 for low, 1 for high).
         */
        if ((data[0] == 0x00) && (data[1] == 0x00)) {
            /* real data, send it to the tty layer */
            tty = tty_port_tty_get(&port->port);
            if (tty) {
                tty_insert_flip_string(tty, data + 2,
                               data_length);
                tty_flip_buffer_push(tty);
                tty_kref_put(tty);
            }
        } else {
            if ((data[0] == 0x00) && (data[1] == 0x01)) {
                spin_lock_irqsave(&priv->lock, flags);
                /* CTS status information package */
                if (data[2] == 0x00)
                    priv->cts = false;
                else
                    priv->cts = true;
                spin_unlock_irqrestore(&priv->lock, flags);
            } else {
                dev_dbg(&priv->udev->dev,
                    "Unknown data packet received from the device:"
                    " %2x %2x\n",
                    data[0], data[1]);
            }
        }
    } 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_bulk_urb(priv->bulk_read_urb, priv->udev,
                  usb_rcvbulkpipe(priv->udev,
                          priv->bulk_address),
                  priv->bulk_in_buffer, priv->buffer_size,
                  opticon_read_bulk_callback, priv);
        result = usb_submit_urb(priv->bulk_read_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 send_control_msg(struct usb_serial_port *port, u8 requesttype,
                u8 val)
{
    struct usb_serial *serial = port->serial;
    int retval;
    u8 *buffer;

    buffer = kzalloc(1, GFP_KERNEL);
    if (!buffer)
        return -ENOMEM;

    buffer[0] = val;
    /* Send the message to the vendor control endpoint
     * of the connected device */
    retval = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                requesttype,
                USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
                0, 0, buffer, 1, 0);
    kfree(buffer);

    return retval;
}

static int opticon_open(struct tty_struct *tty, struct usb_serial_port *port)
{
    struct opticon_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;
    priv->rts = false;
    spin_unlock_irqrestore(&priv->lock, flags);

    /* Clear RTS line */
    send_control_msg(port, CONTROL_RTS, 0);

    /* Setup the read URB and start reading from the device */
    usb_fill_bulk_urb(priv->bulk_read_urb, priv->udev,
              usb_rcvbulkpipe(priv->udev,
                      priv->bulk_address),
              priv->bulk_in_buffer, priv->buffer_size,
              opticon_read_bulk_callback, priv);

    /* clear the halt status of the enpoint */
    usb_clear_halt(priv->udev, priv->bulk_read_urb->pipe);

    result = usb_submit_urb(priv->bulk_read_urb, GFP_KERNEL);
    if (result)
        dev_err(&port->dev,
            "%s - failed resubmitting read urb, error %d\n",
            __func__, result);
    /* Request CTS line state, sometimes during opening the current
     * CTS state can be missed. */
    send_control_msg(port, RESEND_CTS_STATE, 1);
    return result;
}

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

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

static void opticon_write_control_callback(struct urb *urb)
{
    struct opticon_private *priv = urb->context;
    int status = urb->status;
    unsigned long flags;

    /* free up the transfer buffer, as usb_free_urb() does not do this */
    kfree(urb->transfer_buffer);

    /* setup packet may be set if we're using it for writing */
    kfree(urb->setup_packet);

    if (status)
        dev_dbg(&priv->udev->dev, "%s - nonzero write bulk status received: %d\n",
            __func__, status);

    spin_lock_irqsave(&priv->lock, flags);
    --priv->outstanding_urbs;
    spin_unlock_irqrestore(&priv->lock, flags);

    usb_serial_port_softint(priv->port);
}

static int opticon_write(struct tty_struct *tty, struct usb_serial_port *port,
             const unsigned char *buf, int count)
{
    struct opticon_private *priv = usb_get_serial_data(port->serial);
    struct usb_serial *serial = port->serial;
    struct urb *urb;
    unsigned char *buffer;
    unsigned long flags;
    int status;
    struct usb_ctrlrequest *dr;

    spin_lock_irqsave(&priv->lock, flags);
    if (priv->outstanding_urbs > URB_UPPER_LIMIT) {
        spin_unlock_irqrestore(&priv->lock, flags);
        dev_dbg(&port->dev, "%s - write limit hit\n", __func__);
        return 0;
    }
    priv->outstanding_urbs++;
    spin_unlock_irqrestore(&priv->lock, flags);

    buffer = kmalloc(count, GFP_ATOMIC);
    if (!buffer) {
        dev_err(&port->dev, "out of memory\n");
        count = -ENOMEM;

        goto error_no_buffer;
    }

    urb = usb_alloc_urb(0, GFP_ATOMIC);
    if (!urb) {
        dev_err(&port->dev, "no more free urbs\n");
        count = -ENOMEM;
        goto error_no_urb;
    }

    memcpy(buffer, buf, count);

    usb_serial_debug_data(&port->dev, __func__, count, buffer);

    /* The conncected devices do not have a bulk write endpoint,
     * to transmit data to de barcode device the control endpoint is used */
    dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO);
    if (!dr) {
        dev_err(&port->dev, "out of memory\n");
        count = -ENOMEM;
        goto error_no_dr;
    }

    dr->bRequestType = USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_OUT;
    dr->bRequest = 0x01;
    dr->wValue = 0;
    dr->wIndex = 0;
    dr->wLength = cpu_to_le16(count);

    usb_fill_control_urb(urb, serial->dev,
        usb_sndctrlpipe(serial->dev, 0),
        (unsigned char *)dr, buffer, count,
        opticon_write_control_callback, priv);

    /* send it down the pipe */
    status = usb_submit_urb(urb, GFP_ATOMIC);
    if (status) {
        dev_err(&port->dev,
        "%s - usb_submit_urb(write endpoint) failed status = %d\n",
                            __func__, status);
        count = status;
        goto error;
    }

    /* we are done with this urb, so let the host driver
     * really free it when it is finished with it */
    usb_free_urb(urb);

    return count;
error:
    kfree(dr);
error_no_dr:
    usb_free_urb(urb);
error_no_urb:
    kfree(buffer);
error_no_buffer:
    spin_lock_irqsave(&priv->lock, flags);
    --priv->outstanding_urbs;
    spin_unlock_irqrestore(&priv->lock, flags);
    return count;
}

static int opticon_write_room(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    struct opticon_private *priv = usb_get_serial_data(port->serial);
    unsigned long flags;

    /*
     * We really can take almost anything the user throws at us
     * but let's pick a nice big number to tell the tty
     * layer that we have lots of free space, unless we don't.
     */
    spin_lock_irqsave(&priv->lock, flags);
    if (priv->outstanding_urbs > URB_UPPER_LIMIT * 2 / 3) {
        spin_unlock_irqrestore(&priv->lock, flags);
        dev_dbg(&port->dev, "%s - write limit hit\n", __func__);
        return 0;
    }
    spin_unlock_irqrestore(&priv->lock, flags);

    return 2048;
}

static void opticon_throttle(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    struct opticon_private *priv = usb_get_serial_data(port->serial);
    unsigned long flags;

    spin_lock_irqsave(&priv->lock, flags);
    priv->throttled = true;
    spin_unlock_irqrestore(&priv->lock, flags);
}


static void opticon_unthrottle(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    struct opticon_private *priv = usb_get_serial_data(port->serial);
    unsigned long flags;
    int result, was_throttled;

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

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

static int opticon_tiocmget(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    struct opticon_private *priv = usb_get_serial_data(port->serial);
    unsigned long flags;
    int result = 0;

    spin_lock_irqsave(&priv->lock, flags);
    if (priv->rts)
        result |= TIOCM_RTS;
    if (priv->cts)
        result |= TIOCM_CTS;
    spin_unlock_irqrestore(&priv->lock, flags);

    dev_dbg(&port->dev, "%s - %x\n", __func__, result);
    return result;
}

static int opticon_tiocmset(struct tty_struct *tty,
               unsigned int set, unsigned int clear)
{
    struct usb_serial_port *port = tty->driver_data;
    struct usb_serial *serial = port->serial;
    struct opticon_private *priv = usb_get_serial_data(port->serial);
    unsigned long flags;
    bool rts;
    bool changed = false;
    int ret;

    /* We only support RTS so we only handle that */
    spin_lock_irqsave(&priv->lock, flags);

    rts = priv->rts;
    if (set & TIOCM_RTS)
        priv->rts = true;
    if (clear & TIOCM_RTS)
        priv->rts = false;
    changed = rts ^ priv->rts;
    spin_unlock_irqrestore(&priv->lock, flags);

    if (!changed)
        return 0;

    /* Send the new RTS state to the connected device */
    mutex_lock(&serial->disc_mutex);
    if (!serial->disconnected)
        ret = send_control_msg(port, CONTROL_RTS, !rts);
    else
        ret = -ENODEV;
    mutex_unlock(&serial->disc_mutex);

    return ret;
}

static int get_serial_info(struct opticon_private *priv,
               struct serial_struct __user *serial)
{
    struct serial_struct tmp;

    if (!serial)
        return -EFAULT;

    memset(&tmp, 0x00, sizeof(tmp));

    /* fake emulate a 16550 uart to make userspace code happy */
    tmp.type        = PORT_16550A;
    tmp.line        = priv->serial->minor;
    tmp.port        = 0;
    tmp.irq         = 0;
    tmp.flags       = ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ;
    tmp.xmit_fifo_size  = 1024;
    tmp.baud_base       = 9600;
    tmp.close_delay     = 5*HZ;
    tmp.closing_wait    = 30*HZ;

    if (copy_to_user(serial, &tmp, sizeof(*serial)))
        return -EFAULT;
    return 0;
}

static int opticon_ioctl(struct tty_struct *tty,
             unsigned int cmd, unsigned long arg)
{
    struct usb_serial_port *port = tty->driver_data;
    struct opticon_private *priv = usb_get_serial_data(port->serial);

    dev_dbg(&port->dev, "%s - port %d, cmd = 0x%x\n", __func__, port->number, cmd);

    switch (cmd) {
    case TIOCGSERIAL:
        return get_serial_info(priv,
                       (struct serial_struct __user *)arg);
    }

    return -ENOIOCTLCMD;
}

static int opticon_startup(struct usb_serial *serial)
{
    struct opticon_private *priv;
    struct usb_host_interface *intf;
    int i;
    int retval = -ENOMEM;
    bool bulk_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;
    priv->outstanding_urbs = 0; /* Init the outstanding urbs */

    /* find our bulk 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_bulk_in(endpoint))
            continue;

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

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

        priv->bulk_address = endpoint->bEndpointAddress;

        bulk_in_found = true;
        break;
        }

    if (!bulk_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->bulk_read_urb);
    kfree(priv->bulk_in_buffer);
    kfree(priv);
    return retval;
}

static void opticon_disconnect(struct usb_serial *serial)
{
    struct opticon_private *priv = usb_get_serial_data(serial);

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

static void opticon_release(struct usb_serial *serial)
{
    struct opticon_private *priv = usb_get_serial_data(serial);

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

static int opticon_suspend(struct usb_serial *serial, pm_message_t message)
{
    struct opticon_private *priv = usb_get_serial_data(serial);

    usb_kill_urb(priv->bulk_read_urb);
    return 0;
}

static int opticon_resume(struct usb_serial *serial)
{
    struct opticon_private *priv = usb_get_serial_data(serial);
    struct usb_serial_port *port = serial->port[0];
    int result;

    mutex_lock(&port->port.mutex);
    /* This is protected by the port mutex against close/open */
    if (test_bit(ASYNCB_INITIALIZED, &port->port.flags))
        result = usb_submit_urb(priv->bulk_read_urb, GFP_NOIO);
    else
        result = 0;
    mutex_unlock(&port->port.mutex);
    return result;
}

static struct usb_serial_driver opticon_device = {
    .driver = {
        .owner =    THIS_MODULE,
        .name =     "opticon",
    },
    .id_table =     id_table,
    .num_ports =        1,
    .attach =       opticon_startup,
    .open =         opticon_open,
    .close =        opticon_close,
    .write =        opticon_write,
    .write_room =       opticon_write_room,
    .disconnect =       opticon_disconnect,
    .release =      opticon_release,
    .throttle =         opticon_throttle,
    .unthrottle =       opticon_unthrottle,
    .ioctl =        opticon_ioctl,
    .tiocmget =     opticon_tiocmget,
    .tiocmset =     opticon_tiocmset,
    .suspend =      opticon_suspend,
    .resume =       opticon_resume,
};

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

module_usb_serial_driver(serial_drivers, id_table);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");