/*
 * Opticon USB barcode to serial driver
 *
 * Copyright (C) 2011 Martin Jansen <martin.jansen@opticon.com>
 * Copyright (C) 2008 - 2009 Greg Kroah-Hartman <gregkh@suse.de>
 * 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 bool debug;

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 */
                dbg("%s - urb shutting down with status: %d",
                    __func__, status);
                return;
        default:
                dbg("%s - nonzero urb status received: %d",
                    __func__, status);
                goto exit;
        }

        usb_serial_debug_data(debug, &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[2];

        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);

        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)
                dbg("%s - nonzero write bulk status received: %d",
                    __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);
                dbg("%s - write limit hit", __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(debug, &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;
        }

        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:
        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);
                dbg("%s - write limit hit", __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);

        dbg("%s - %x", __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);

        dbg("%s - port %d, cmd = 0x%x", __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");

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug enabled or not");