/*
 * USB Empeg empeg-car player driver
 *
 *      Copyright (C) 2000, 2001
 *          Gary Brubaker (xavyer@ix.netcom.com)
 *
 *      Copyright (C) 1999 - 2001
 *          Greg Kroah-Hartman (greg@kroah.com)
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License, as published by
 *      the Free Software Foundation, version 2.
 *
 * See Documentation/usb/usb-serial.txt for more information on using this
 * driver
 *
 * (07/16/2001) gb
 *      remove unused code in empeg_close() (thanks to Oliver Neukum for
 *      pointing this out) and rewrote empeg_set_termios().
 *
 * (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.
 *
 * (01/22/2001) gb
 *      Added write_room() and chars_in_buffer() support.
 *
 * (12/21/2000) gb
 *      Moved termio stuff inside the port->active check.
 *      Moved MOD_DEC_USE_COUNT to end of empeg_close().
 *
 * (12/03/2000) gb
 *      Added port->port.tty->ldisc.set_termios(port->port.tty, NULL) to
 *      empeg_open(). This notifies the tty driver that the termios have
 *      changed.
 *
 * (11/13/2000) gb
 *      Moved tty->low_latency = 1 from empeg_read_bulk_callback() to
 *      empeg_open() (It only needs to be set once - Doh!)
 *
 * (11/11/2000) gb
 *      Updated to work with id_table structure.
 *
 * (11/04/2000) gb
 *      Forked this from visor.c, and hacked it up to work with an
 *      Empeg ltd. empeg-car player.  Constructive criticism welcomed.
 *      I would like to say, 'Thank You' to Greg Kroah-Hartman for the
 *      use of his code, and for his guidance, advice and patience. :)
 *      A 'Thank You' is in order for John Ripley of Empeg ltd for his
 *      advice, and patience too.
 *
 */

#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 "v1.2"
#define DRIVER_AUTHOR "Greg Kroah-Hartman <greg@kroah.com>, Gary Brubaker <xavyer@ix.netcom.com>"
#define DRIVER_DESC "USB Empeg Mark I/II Driver"

#define EMPEG_VENDOR_ID                 0x084f
#define EMPEG_PRODUCT_ID                0x0001

/* function prototypes for an empeg-car player */
static int  empeg_open(struct tty_struct *tty, struct usb_serial_port *port,
                                                struct file *filp);
static void empeg_close(struct tty_struct *tty, struct usb_serial_port *port,
                                                struct file *filp);
static int  empeg_write(struct tty_struct *tty, struct usb_serial_port *port,
                                                const unsigned char *buf,
                                                int count);
static int  empeg_write_room(struct tty_struct *tty);
static int  empeg_chars_in_buffer(struct tty_struct *tty);
static void empeg_throttle(struct tty_struct *tty);
static void empeg_unthrottle(struct tty_struct *tty);
static int  empeg_startup(struct usb_serial *serial);
static void empeg_set_termios(struct tty_struct *tty,
                struct usb_serial_port *port, struct ktermios *old_termios);
static void empeg_write_bulk_callback(struct urb *urb);
static void empeg_read_bulk_callback(struct urb *urb);

static struct usb_device_id id_table [] = {
        { USB_DEVICE(EMPEG_VENDOR_ID, EMPEG_PRODUCT_ID) },
        { }                                     /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, id_table);

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

static struct usb_serial_driver empeg_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "empeg",
        },
        .id_table =             id_table,
        .usb_driver =           &empeg_driver,
        .num_ports =            1,
        .open =                 empeg_open,
        .close =                empeg_close,
        .throttle =             empeg_throttle,
        .unthrottle =           empeg_unthrottle,
        .attach =               empeg_startup,
        .set_termios =          empeg_set_termios,
        .write =                empeg_write,
        .write_room =           empeg_write_room,
        .chars_in_buffer =      empeg_chars_in_buffer,
        .write_bulk_callback =  empeg_write_bulk_callback,
        .read_bulk_callback =   empeg_read_bulk_callback,
};

#define NUM_URBS                        16
#define URB_TRANSFER_BUFFER_SIZE        4096

static struct urb       *write_urb_pool[NUM_URBS];
static spinlock_t       write_urb_pool_lock;
static int              bytes_in;
static int              bytes_out;

/******************************************************************************
 * Empeg specific driver functions
 ******************************************************************************/
static int empeg_open(struct tty_struct *tty, struct usb_serial_port *port,
                                struct file *filp)
{
        struct usb_serial *serial = port->serial;
        int result = 0;

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

        /* Force default termio settings */
        empeg_set_termios(tty, port, NULL) ;

        bytes_in = 0;
        bytes_out = 0;

        /* 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,
                empeg_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 empeg_close(struct tty_struct *tty, struct usb_serial_port *port,
                                struct file *filp)
{
        dbg("%s - port %d", __func__, port->number);

        /* shutdown our bulk read */
        usb_kill_urb(port->read_urb);
        /* Uncomment the following line if you want to see some statistics in your syslog */
        /* dev_info (&port->dev, "Bytes In = %d  Bytes Out = %d\n", bytes_in, bytes_out); */
}


static int empeg_write(struct tty_struct *tty, struct usb_serial_port *port,
                                        const unsigned char *buf, int count)
{
        struct usb_serial *serial = port->serial;
        struct urb *urb;
        const unsigned char *current_position = buf;
        unsigned long flags;
        int status;
        int i;
        int bytes_sent = 0;
        int transfer_size;

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

        while (count > 0) {
                /* try to find a free urb in our list of them */
                urb = NULL;

                spin_lock_irqsave(&write_urb_pool_lock, flags);

                for (i = 0; i < NUM_URBS; ++i) {
                        if (write_urb_pool[i]->status != -EINPROGRESS) {
                                urb = write_urb_pool[i];
                                break;
                        }
                }

                spin_unlock_irqrestore(&write_urb_pool_lock, flags);

                if (urb == NULL) {
                        dbg("%s - no more free urbs", __func__);
                        goto exit;
                }

                if (urb->transfer_buffer == NULL) {
                        urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE, GFP_ATOMIC);
                        if (urb->transfer_buffer == NULL) {
                                dev_err(&port->dev,
                                        "%s no more kernel memory...\n",
                                                                __func__);
                                goto exit;
                        }
                }

                transfer_size = min(count, URB_TRANSFER_BUFFER_SIZE);

                memcpy(urb->transfer_buffer, current_position, transfer_size);

                usb_serial_debug_data(debug, &port->dev, __func__, transfer_size, urb->transfer_buffer);

                /* build up our urb */
                usb_fill_bulk_urb(
                        urb,
                        serial->dev,
                        usb_sndbulkpipe(serial->dev,
                                        port->bulk_out_endpointAddress),
                        urb->transfer_buffer,
                        transfer_size,
                        empeg_write_bulk_callback,
                        port);

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

                current_position += transfer_size;
                bytes_sent += transfer_size;
                count -= transfer_size;
                bytes_out += transfer_size;

        }
exit:
        return bytes_sent;
}


static int empeg_write_room(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        unsigned long flags;
        int i;
        int room = 0;

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

        spin_lock_irqsave(&write_urb_pool_lock, flags);
        /* tally up the number of bytes available */
        for (i = 0; i < NUM_URBS; ++i) {
                if (write_urb_pool[i]->status != -EINPROGRESS)
                        room += URB_TRANSFER_BUFFER_SIZE;
        }
        spin_unlock_irqrestore(&write_urb_pool_lock, flags);
        dbg("%s - returns %d", __func__, room);
        return room;

}


static int empeg_chars_in_buffer(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        unsigned long flags;
        int i;
        int chars = 0;

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

        spin_lock_irqsave(&write_urb_pool_lock, flags);

        /* tally up the number of bytes waiting */
        for (i = 0; i < NUM_URBS; ++i) {
                if (write_urb_pool[i]->status == -EINPROGRESS)
                        chars += URB_TRANSFER_BUFFER_SIZE;
        }

        spin_unlock_irqrestore(&write_urb_pool_lock, flags);
        dbg("%s - returns %d", __func__, chars);
        return chars;
}


static void empeg_write_bulk_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        int status = urb->status;

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

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

        usb_serial_port_softint(port);
}


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

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

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

        usb_serial_debug_data(debug, &port->dev, __func__,
                                                urb->actual_length, data);
        tty = port->port.tty;

        if (urb->actual_length) {
                tty_buffer_request_room(tty, urb->actual_length);
                tty_insert_flip_string(tty, data, urb->actual_length);
                tty_flip_buffer_push(tty);
                bytes_in += urb->actual_length;
        }

        /* Continue trying to always read  */
        usb_fill_bulk_urb(
                port->read_urb,
                port->serial->dev,
                usb_rcvbulkpipe(port->serial->dev,
                        port->bulk_in_endpointAddress),
                port->read_urb->transfer_buffer,
                port->read_urb->transfer_buffer_length,
                empeg_read_bulk_callback,
                port);

        result = usb_submit_urb(port->read_urb, GFP_ATOMIC);

        if (result)
                dev_err(&urb->dev->dev,
                        "%s - failed resubmitting read urb, error %d\n",
                                                        __func__, result);

        return;

}


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


static void empeg_unthrottle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        int result;
        dbg("%s - port %d", __func__, port->number);

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


static int  empeg_startup(struct usb_serial *serial)
{
        int r;

        dbg("%s", __func__);

        if (serial->dev->actconfig->desc.bConfigurationValue != 1) {
                err("active config #%d != 1 ??",
                        serial->dev->actconfig->desc.bConfigurationValue);
                return -ENODEV;
        }
        dbg("%s - reset config", __func__);
        r = usb_reset_configuration(serial->dev);

        /* continue on with initialization */
        return r;

}


static void empeg_set_termios(struct tty_struct *tty,
                struct usb_serial_port *port, struct ktermios *old_termios)
{
        struct ktermios *termios = tty->termios;
        dbg("%s - port %d", __func__, port->number);

        /*
         * The empeg-car player wants these particular tty settings.
         * You could, for example, change the baud rate, however the
         * player only supports 115200 (currently), so there is really
         * no point in support for changes to the tty settings.
         * (at least for now)
         *
         * The default requirements for this device are:
         */
        termios->c_iflag
                &= ~(IGNBRK     /* disable ignore break */
                | BRKINT        /* disable break causes interrupt */
                | PARMRK        /* disable mark parity errors */
                | ISTRIP        /* disable clear high bit of input characters */
                | INLCR         /* disable translate NL to CR */
                | IGNCR         /* disable ignore CR */
                | ICRNL         /* disable translate CR to NL */
                | IXON);        /* disable enable XON/XOFF flow control */

        termios->c_oflag
                &= ~OPOST;      /* disable postprocess output characters */

        termios->c_lflag
                &= ~(ECHO       /* disable echo input characters */
                | ECHONL        /* disable echo new line */
                | ICANON        /* disable erase, kill, werase, and rprnt special characters */
                | ISIG          /* disable interrupt, quit, and suspend special characters */
                | IEXTEN);      /* disable non-POSIX special characters */

        termios->c_cflag
                &= ~(CSIZE      /* no size */
                | PARENB        /* disable parity bit */
                | CBAUD);       /* clear current baud rate */

        termios->c_cflag
                |= CS8;         /* character size 8 bits */

        tty_encode_baud_rate(tty, 115200, 115200);
}


static int __init empeg_init(void)
{
        struct urb *urb;
        int i, retval;

        /* create our write urb pool and transfer buffers */
        spin_lock_init(&write_urb_pool_lock);
        for (i = 0; i < NUM_URBS; ++i) {
                urb = usb_alloc_urb(0, GFP_KERNEL);
                write_urb_pool[i] = urb;
                if (urb == NULL) {
                        err("No more urbs???");
                        continue;
                }

                urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE,
                                                                GFP_KERNEL);
                if (!urb->transfer_buffer) {
                        err("%s - out of memory for urb buffers.",
                            __func__);
                        continue;
                }
        }

        retval = usb_serial_register(&empeg_device);
        if (retval)
                goto failed_usb_serial_register;
        retval = usb_register(&empeg_driver);
        if (retval)
                goto failed_usb_register;

        info(DRIVER_VERSION ":" DRIVER_DESC);

        return 0;
failed_usb_register:
        usb_serial_deregister(&empeg_device);
failed_usb_serial_register:
        for (i = 0; i < NUM_URBS; ++i) {
                if (write_urb_pool[i]) {
                        kfree(write_urb_pool[i]->transfer_buffer);
                        usb_free_urb(write_urb_pool[i]);
                }
        }
        return retval;
}


static void __exit empeg_exit(void)
{
        int i;
        unsigned long flags;

        usb_deregister(&empeg_driver);
        usb_serial_deregister(&empeg_device);

        spin_lock_irqsave(&write_urb_pool_lock, flags);

        for (i = 0; i < NUM_URBS; ++i) {
                if (write_urb_pool[i]) {
                        /* FIXME - uncomment the following usb_kill_urb call
                         * when the host controllers get fixed to set urb->dev
                         * = NULL after the urb is finished.  Otherwise this
                         * call oopses. */
                        /* usb_kill_urb(write_urb_pool[i]); */
                        kfree(write_urb_pool[i]->transfer_buffer);
                        usb_free_urb(write_urb_pool[i]);
                }
        }
        spin_unlock_irqrestore(&write_urb_pool_lock, flags);
}


module_init(empeg_init);
module_exit(empeg_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");