/*
 * USB ZyXEL omni.net LCD PLUS driver
 *
 *      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.
 *
 * See Documentation/usb/usb-serial.txt for more information on using this
 * driver
 *
 * Please report both successes and troubles to the author at omninet@kroah.com
 *
 * (05/30/2001) gkh
 *      switched from using spinlock to a semaphore, which fixes lots of
 *      problems.
 *
 * (04/08/2001) gb
 *      Identify version on module load.
 *
 * (11/01/2000) Adam J. Richter
 *      usb_device_id table support
 *
 * (10/05/2000) gkh
 *      Fixed bug with urb->dev not being set properly, now that the usb
 *      core needs it.
 *
 * (08/28/2000) gkh
 *      Added locks for SMP safeness.
 *      Fixed MOD_INC and MOD_DEC logic and the ability to open a port more
 *      than once.
 *      Fixed potential race in omninet_write_bulk_callback
 *
 * (07/19/2000) gkh
 *      Added module_init and module_exit functions to handle the fact that this
 *      driver is a loadable module now.
 *
 */

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

static int debug;

/*
 * Version Information
 */
#define DRIVER_VERSION "v1.1"
#define DRIVER_AUTHOR "Alessandro Zummo"
#define DRIVER_DESC "USB ZyXEL omni.net LCD PLUS Driver"

#define ZYXEL_VENDOR_ID         0x0586
#define ZYXEL_OMNINET_ID        0x1000
/* This one seems to be a re-branded ZyXEL device */
#define BT_IGNITIONPRO_ID       0x2000

/* function prototypes */
static int  omninet_open(struct tty_struct *tty, struct usb_serial_port *port,
                                                        struct file *filp);
static void omninet_close(struct tty_struct *tty, struct usb_serial_port *port,
                                                        struct file *filp);
static void omninet_read_bulk_callback(struct urb *urb);
static void omninet_write_bulk_callback(struct urb *urb);
static int  omninet_write(struct tty_struct *tty, struct usb_serial_port *port,
                                const unsigned char *buf, int count);
static int  omninet_write_room(struct tty_struct *tty);
static void omninet_shutdown(struct usb_serial *serial);
static int omninet_attach(struct usb_serial *serial);

static struct usb_device_id id_table[] = {
        { USB_DEVICE(ZYXEL_VENDOR_ID, ZYXEL_OMNINET_ID) },
        { USB_DEVICE(ZYXEL_VENDOR_ID, BT_IGNITIONPRO_ID) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, id_table);

static struct usb_driver omninet_driver = {
        .name =         "omninet",
        .probe =        usb_serial_probe,
        .disconnect =   usb_serial_disconnect,
        .id_table =     id_table,
        .no_dynamic_id =        1,
};


static struct usb_serial_driver zyxel_omninet_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "omninet",
        },
        .description =          "ZyXEL - omni.net lcd plus usb",
        .usb_driver =           &omninet_driver,
        .id_table =             id_table,
        .num_ports =            1,
        .attach =               omninet_attach,
        .open =                 omninet_open,
        .close =                omninet_close,
        .write =                omninet_write,
        .write_room =           omninet_write_room,
        .read_bulk_callback =   omninet_read_bulk_callback,
        .write_bulk_callback =  omninet_write_bulk_callback,
        .shutdown =             omninet_shutdown,
};


/* The protocol.
 *
 * The omni.net always exchange 64 bytes of data with the host. The first
 * four bytes are the control header, you can see it in the above structure.
 *
 * oh_seq is a sequence number. Don't know if/how it's used.
 * oh_len is the length of the data bytes in the packet.
 * oh_xxx Bit-mapped, related to handshaking and status info.
 *      I normally set it to 0x03 in trasmitted frames.
 *      7: Active when the TA is in a CONNECTed state.
 *      6: unknown
 *      5: handshaking, unknown
 *      4: handshaking, unknown
 *      3: unknown, usually 0
 *      2: unknown, usually 0
 *      1: handshaking, unknown, usually set to 1 in trasmitted frames
 *      0: handshaking, unknown, usually set to 1 in trasmitted frames
 * oh_pad Probably a pad byte.
 *
 * After the header you will find data bytes if oh_len was greater than zero.
 *
 */

struct omninet_header {
        __u8    oh_seq;
        __u8    oh_len;
        __u8    oh_xxx;
        __u8    oh_pad;
};

struct omninet_data {
        __u8    od_outseq;      /* Sequence number for bulk_out URBs */
};

static int omninet_attach(struct usb_serial *serial)
{
        struct omninet_data *od;
        struct usb_serial_port *port = serial->port[0];

        od = kmalloc(sizeof(struct omninet_data), GFP_KERNEL);
        if (!od) {
                dev_err(&port->dev, "%s- kmalloc(%Zd) failed.\n",
                        __func__, sizeof(struct omninet_data));
                return -ENOMEM;
        }
        usb_set_serial_port_data(port, od);
        return 0;
}

static int omninet_open(struct tty_struct *tty,
                        struct usb_serial_port *port, struct file *filp)
{
        struct usb_serial       *serial = port->serial;
        struct usb_serial_port  *wport;
        int                     result = 0;

        dbg("%s - port %d", __func__, port->number);

        wport = serial->port[1];
        tty_port_tty_set(&wport->port, tty);

        /* Start reading from the device */
        usb_fill_bulk_urb(port->read_urb, serial->dev,
                        usb_rcvbulkpipe(serial->dev,
                                port->bulk_in_endpointAddress),
                        port->read_urb->transfer_buffer,
                        port->read_urb->transfer_buffer_length,
                        omninet_read_bulk_callback, port);
        result = usb_submit_urb(port->read_urb, GFP_KERNEL);
        if (result)
                dev_err(&port->dev,
                        "%s - failed submitting read urb, error %d\n",
                        __func__, result);
        return result;
}

static void omninet_close(struct tty_struct *tty,
                        struct usb_serial_port *port, struct file *filp)
{
        dbg("%s - port %d", __func__, port->number);
        usb_kill_urb(port->read_urb);
}


#define OMNINET_DATAOFFSET      0x04
#define OMNINET_HEADERLEN       sizeof(struct omninet_header)
#define OMNINET_BULKOUTSIZE     (64 - OMNINET_HEADERLEN)

static void omninet_read_bulk_callback(struct urb *urb)
{
        struct usb_serial_port  *port   = urb->context;
        unsigned char           *data   = urb->transfer_buffer;
        struct omninet_header   *header = (struct omninet_header *) &data[0];
        int status = urb->status;
        int result;
        int i;

        dbg("%s - port %d", __func__, port->number);

        if (status) {
                dbg("%s - nonzero read bulk status received: %d",
                    __func__, status);
                return;
        }

        if (debug && header->oh_xxx != 0x30) {
                if (urb->actual_length) {
                        printk(KERN_DEBUG __FILE__
                                        ": omninet_read %d: ", header->oh_len);
                        for (i = 0; i < (header->oh_len +
                                                OMNINET_HEADERLEN); i++)
                                printk("%.2x ", data[i]);
                        printk("\n");
                }
        }

        if (urb->actual_length && header->oh_len) {
                struct tty_struct *tty = tty_port_tty_get(&port->port);
                tty_insert_flip_string(tty, data + OMNINET_DATAOFFSET,
                                                        header->oh_len);
                tty_flip_buffer_push(tty);
                tty_kref_put(tty);
        }

        /* Continue trying to always read  */
        usb_fill_bulk_urb(urb, port->serial->dev,
                        usb_rcvbulkpipe(port->serial->dev,
                                        port->bulk_in_endpointAddress),
                        urb->transfer_buffer, urb->transfer_buffer_length,
                        omninet_read_bulk_callback, port);
        result = usb_submit_urb(urb, GFP_ATOMIC);
        if (result)
                dev_err(&port->dev,
                        "%s - failed resubmitting read urb, error %d\n",
                        __func__, result);

        return;
}

static int omninet_write(struct tty_struct *tty, struct usb_serial_port *port,
                                        const unsigned char *buf, int count)
{
        struct usb_serial *serial = port->serial;
        struct usb_serial_port *wport = serial->port[1];

        struct omninet_data *od = usb_get_serial_port_data(port);
        struct omninet_header *header = (struct omninet_header *)
                                        wport->write_urb->transfer_buffer;

        int                     result;

        dbg("%s - port %d", __func__, port->number);

        if (count == 0) {
                dbg("%s - write request of 0 bytes", __func__);
                return 0;
        }

        spin_lock_bh(&wport->lock);
        if (wport->write_urb_busy) {
                spin_unlock_bh(&wport->lock);
                dbg("%s - already writing", __func__);
                return 0;
        }
        wport->write_urb_busy = 1;
        spin_unlock_bh(&wport->lock);

        count = (count > OMNINET_BULKOUTSIZE) ? OMNINET_BULKOUTSIZE : count;

        memcpy(wport->write_urb->transfer_buffer + OMNINET_DATAOFFSET,
                                                                buf, count);

        usb_serial_debug_data(debug, &port->dev, __func__, count,
                                        wport->write_urb->transfer_buffer);

        header->oh_seq  = od->od_outseq++;
        header->oh_len  = count;
        header->oh_xxx  = 0x03;
        header->oh_pad  = 0x00;

        /* send the data out the bulk port, always 64 bytes */
        wport->write_urb->transfer_buffer_length = 64;

        wport->write_urb->dev = serial->dev;
        result = usb_submit_urb(wport->write_urb, GFP_ATOMIC);
        if (result) {
                wport->write_urb_busy = 0;
                dev_err(&port->dev,
                        "%s - failed submitting write urb, error %d\n",
                        __func__, result);
        } else
                result = count;

        return result;
}


static int omninet_write_room(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial       *serial = port->serial;
        struct usb_serial_port  *wport  = serial->port[1];

        int room = 0; /* Default: no room */

        /* FIXME: no consistent locking for write_urb_busy */
        if (wport->write_urb_busy)
                room = wport->bulk_out_size - OMNINET_HEADERLEN;

        dbg("%s - returns %d", __func__, room);

        return room;
}

static void omninet_write_bulk_callback(struct urb *urb)
{
/*      struct omninet_header   *header = (struct omninet_header  *)
                                                urb->transfer_buffer; */
        struct usb_serial_port  *port   =  urb->context;
        int status = urb->status;

        dbg("%s - port %0x\n", __func__, port->number);

        port->write_urb_busy = 0;
        if (status) {
                dbg("%s - nonzero write bulk status received: %d",
                    __func__, status);
                return;
        }

        usb_serial_port_softint(port);
}


static void omninet_shutdown(struct usb_serial *serial)
{
        struct usb_serial_port *wport = serial->port[1];
        struct usb_serial_port *port = serial->port[0];
        dbg("%s", __func__);

        usb_kill_urb(wport->write_urb);
        kfree(usb_get_serial_port_data(port));
}


static int __init omninet_init(void)
{
        int retval;
        retval = usb_serial_register(&zyxel_omninet_device);
        if (retval)
                goto failed_usb_serial_register;
        retval = usb_register(&omninet_driver);
        if (retval)
                goto failed_usb_register;
        printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
               DRIVER_DESC "\n");
        return 0;
failed_usb_register:
        usb_serial_deregister(&zyxel_omninet_device);
failed_usb_serial_register:
        return retval;
}


static void __exit omninet_exit(void)
{
        usb_deregister(&omninet_driver);
        usb_serial_deregister(&zyxel_omninet_device);
}


module_init(omninet_init);
module_exit(omninet_exit);

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

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