Linux-2.6.12-rc2

[thirdparty/linux.git] / drivers / usb / serial / digi_acceleport.c

/*
*  Digi AccelePort USB-4 and USB-2 Serial Converters
*
*  Copyright 2000 by Digi International
*
*  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; either version 2 of the License, or
*  (at your option) any later version.
*
*  Shamelessly based on Brian Warner's keyspan_pda.c and Greg Kroah-Hartman's
*  usb-serial driver.
*
*  Peter Berger (pberger@brimson.com)
*  Al Borchers (borchers@steinerpoint.com)
* 
* (12/03/2001) gkh
*       switched to using port->open_count instead of private version.
*       Removed port->active
*
* (04/08/2001) gb
*       Identify version on module load.
*
* (11/01/2000) Adam J. Richter
*       usb_device_id table support
* 
* (11/01/2000) pberger and borchers
*    -- Turned off the USB_DISABLE_SPD flag for write bulk urbs--it caused
*       USB 4 ports to hang on startup.
*    -- Serialized access to write urbs by adding the dp_write_urb_in_use
*       flag; otherwise, the driver caused SMP system hangs.  Watching the
*       urb status is not sufficient.
*
* (10/05/2000) gkh
*    -- Fixed bug with urb->dev not being set properly, now that the usb
*       core needs it.
* 
*  (8/8/2000) pberger and borchers
*    -- Fixed close so that 
*       - it can timeout while waiting for transmit idle, if needed;
*       - it ignores interrupts when flushing the port, turning
*         of modem signalling, and so on;
*       - it waits for the flush to really complete before returning.
*    -- Read_bulk_callback and write_bulk_callback check for a closed
*       port before using the tty struct or writing to the port.
*    -- The two changes above fix the oops caused by interrupted closes.
*    -- Added interruptible args to write_oob_command and set_modem_signals
*       and added a timeout arg to transmit_idle; needed for fixes to
*       close.
*    -- Added code for rx_throttle and rx_unthrottle so that input flow
*       control works.
*    -- Added code to set overrun, parity, framing, and break errors
*       (untested).
*    -- Set USB_DISABLE_SPD flag for write bulk urbs, so no 0 length
*       bulk writes are done.  These hung the Digi USB device.  The
*       0 length bulk writes were a new feature of usb-uhci added in
*       the 2.4.0-test6 kernels.
*    -- Fixed mod inc race in open; do mod inc before sleeping to wait
*       for a close to finish.
*
*  (7/31/2000) pberger
*    -- Fixed bugs with hardware handshaking:
*       - Added code to set/clear tty->hw_stopped in digi_read_oob_callback()
*         and digi_set_termios()
*    -- Added code in digi_set_termios() to
*       - add conditional in code handling transition from B0 to only
*         set RTS if RTS/CTS flow control is either not in use or if
*         the port is not currently throttled.
*       - handle turning off CRTSCTS.
*
*  (7/30/2000) borchers
*    -- Added support for more than one Digi USB device by moving
*       globals to a private structure in the pointed to from the
*       usb_serial structure.
*    -- Moved the modem change and transmit idle wait queues into
*       the port private structure, so each port has its own queue
*       rather than sharing global queues.
*    -- Added support for break signals.
*
*  (7/25/2000) pberger
*    -- Added USB-2 support.  Note: the USB-2 supports 3 devices: two
*       serial and a parallel port.  The parallel port is implemented
*       as a serial-to-parallel converter.  That is, the driver actually
*       presents all three USB-2 interfaces as serial ports, but the third
*       one physically connects to a parallel device.  Thus, for example,
*       one could plug a parallel printer into the USB-2's third port,
*       but from the kernel's (and userland's) point of view what's
*       actually out there is a serial device.
*
*  (7/15/2000) borchers
*    -- Fixed race in open when a close is in progress.
*    -- Keep count of opens and dec the module use count for each
*       outstanding open when shutdown is called (on disconnect).
*    -- Fixed sanity checks in read_bulk_callback and write_bulk_callback
*       so pointers are checked before use.
*    -- Split read bulk callback into in band and out of band
*       callbacks, and no longer restart read chains if there is
*       a status error or a sanity error.  This fixed the seg
*       faults and other errors we used to get on disconnect.
*    -- Port->active is once again a flag as usb-serial intended it
*       to be, not a count.  Since it was only a char it would
*       have been limited to 256 simultaneous opens.  Now the open
*       count is kept in the port private structure in dp_open_count.
*    -- Added code for modularization of the digi_acceleport driver.
*
*  (6/27/2000) pberger and borchers
*    -- Zeroed out sync field in the wakeup_task before first use;
*       otherwise the uninitialized value might prevent the task from
*       being scheduled.
*    -- Initialized ret value to 0 in write_bulk_callback, otherwise
*       the uninitialized value could cause a spurious debugging message.
*
*  (6/22/2000) pberger and borchers
*    -- Made cond_wait_... inline--apparently on SPARC the flags arg
*       to spin_lock_irqsave cannot be passed to another function
*       to call spin_unlock_irqrestore.  Thanks to Pauline Middelink.
*    -- In digi_set_modem_signals the inner nested spin locks use just
*       spin_lock() rather than spin_lock_irqsave().  The old code
*       mistakenly left interrupts off.  Thanks to Pauline Middelink.
*    -- copy_from_user (which can sleep) is no longer called while a
*       spinlock is held.  We copy to a local buffer before getting
*       the spinlock--don't like the extra copy but the code is simpler.
*    -- Printk and dbg are no longer called while a spin lock is held.
*
*  (6/4/2000) pberger and borchers
*    -- Replaced separate calls to spin_unlock_irqrestore and
*       interruptible_sleep_on_timeout with a new function
*       cond_wait_interruptible_timeout_irqrestore.  This eliminates
*       the race condition where the wake up could happen after
*       the unlock and before the sleep.
*    -- Close now waits for output to drain.
*    -- Open waits until any close in progress is finished.
*    -- All out of band responses are now processed, not just the
*       first in a USB packet.
*    -- Fixed a bug that prevented the driver from working when the
*       first Digi port was not the first USB serial port--the driver
*       was mistakenly using the external USB serial port number to
*       try to index into its internal ports.
*    -- Fixed an SMP bug -- write_bulk_callback is called directly from
*       an interrupt, so spin_lock_irqsave/spin_unlock_irqrestore are
*       needed for locks outside write_bulk_callback that are also
*       acquired by write_bulk_callback to prevent deadlocks.
*    -- Fixed support for select() by making digi_chars_in_buffer()
*       return 256 when -EINPROGRESS is set, as the line discipline
*       code in n_tty.c expects.
*    -- Fixed an include file ordering problem that prevented debugging
*       messages from working.
*    -- Fixed an intermittent timeout problem that caused writes to
*       sometimes get stuck on some machines on some kernels.  It turns
*       out in these circumstances write_chan() (in n_tty.c) was
*       asleep waiting for our wakeup call.  Even though we call
*       wake_up_interruptible() in digi_write_bulk_callback(), there is
*       a race condition that could cause the wakeup to fail: if our
*       wake_up_interruptible() call occurs between the time that our
*       driver write routine finishes and write_chan() sets current->state
*       to TASK_INTERRUPTIBLE, the effect of our wakeup setting the state
*       to TASK_RUNNING will be lost and write_chan's subsequent call to
*       schedule() will never return (unless it catches a signal).
*       This race condition occurs because write_bulk_callback() (and thus
*       the wakeup) are called asynchonously from an interrupt, rather than
*       from the scheduler.  We can avoid the race by calling the wakeup
*       from the scheduler queue and that's our fix:  Now, at the end of
*       write_bulk_callback() we queue up a wakeup call on the scheduler
*       task queue.  We still also invoke the wakeup directly since that
*       squeezes a bit more performance out of the driver, and any lost
*       race conditions will get cleaned up at the next scheduler run.
*
*       NOTE:  The problem also goes away if you comment out
*       the two code lines in write_chan() where current->state
*       is set to TASK_RUNNING just before calling driver.write() and to
*       TASK_INTERRUPTIBLE immediately afterwards.  This is why the
*       problem did not show up with the 2.2 kernels -- they do not
*       include that code.
*
*  (5/16/2000) pberger and borchers
*    -- Added timeouts to sleeps, to defend against lost wake ups.
*    -- Handle transition to/from B0 baud rate in digi_set_termios.
*
*  (5/13/2000) pberger and borchers
*    -- All commands now sent on out of band port, using
*       digi_write_oob_command.
*    -- Get modem control signals whenever they change, support TIOCMGET/
*       SET/BIS/BIC ioctls.
*    -- digi_set_termios now supports parity, word size, stop bits, and
*       receive enable.
*    -- Cleaned up open and close, use digi_set_termios and
*       digi_write_oob_command to set port parameters.
*    -- Added digi_startup_device to start read chains on all ports.
*    -- Write buffer is only used when count==1, to be sure put_char can
*       write a char (unless the buffer is full).
*
*  (5/10/2000) pberger and borchers
*    -- Added MOD_INC_USE_COUNT/MOD_DEC_USE_COUNT calls on open/close.
*    -- Fixed problem where the first incoming character is lost on
*       port opens after the first close on that port.  Now we keep
*       the read_urb chain open until shutdown.
*    -- Added more port conditioning calls in digi_open and digi_close.
*    -- Convert port->active to a use count so that we can deal with multiple
*       opens and closes properly.
*    -- Fixed some problems with the locking code.
*
*  (5/3/2000) pberger and borchers
*    -- First alpha version of the driver--many known limitations and bugs.
*
*
*  Locking and SMP
*
*  - Each port, including the out-of-band port, has a lock used to
*    serialize all access to the port's private structure.
*  - The port lock is also used to serialize all writes and access to
*    the port's URB.
*  - The port lock is also used for the port write_wait condition
*    variable.  Holding the port lock will prevent a wake up on the
*    port's write_wait; this can be used with cond_wait_... to be sure
*    the wake up is not lost in a race when dropping the lock and
*    sleeping waiting for the wakeup.
*  - digi_write() does not sleep, since it is sometimes called on
*    interrupt time.
*  - digi_write_bulk_callback() and digi_read_bulk_callback() are
*    called directly from interrupts.  Hence spin_lock_irqsave()
*    and spin_unlock_irqrestore() are used in the rest of the code
*    for any locks they acquire.
*  - digi_write_bulk_callback() gets the port lock before waking up
*    processes sleeping on the port write_wait.  It also schedules
*    wake ups so they happen from the scheduler, because the tty
*    system can miss wake ups from interrupts.
*  - All sleeps use a timeout of DIGI_RETRY_TIMEOUT before looping to
*    recheck the condition they are sleeping on.  This is defensive,
*    in case a wake up is lost.
*  - Following Documentation/DocBook/kernel-locking.pdf no spin locks
*    are held when calling copy_to/from_user or printk.
*    
*  $Id: digi_acceleport.c,v 1.80.1.2 2000/11/02 05:45:08 root Exp $
*/

#include <linux/config.h>
#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/workqueue.h>
#include <asm/uaccess.h>
#include <linux/usb.h>
#include <linux/wait.h>
#include "usb-serial.h"

/* Defines */

/*
 * Version Information
 */
#define DRIVER_VERSION "v1.80.1.2"
#define DRIVER_AUTHOR "Peter Berger <pberger@brimson.com>, Al Borchers <borchers@steinerpoint.com>"
#define DRIVER_DESC "Digi AccelePort USB-2/USB-4 Serial Converter driver"

/* port output buffer length -- must be <= transfer buffer length - 2 */
/* so we can be sure to send the full buffer in one urb */
#define DIGI_OUT_BUF_SIZE               8

/* port input buffer length -- must be >= transfer buffer length - 3 */
/* so we can be sure to hold at least one full buffer from one urb */
#define DIGI_IN_BUF_SIZE                64

/* retry timeout while sleeping */
#define DIGI_RETRY_TIMEOUT              (HZ/10)

/* timeout while waiting for tty output to drain in close */
/* this delay is used twice in close, so the total delay could */
/* be twice this value */
#define DIGI_CLOSE_TIMEOUT              (5*HZ)


/* AccelePort USB Defines */

/* ids */
#define DIGI_VENDOR_ID                  0x05c5
#define DIGI_2_ID                       0x0002  /* USB-2 */
#define DIGI_4_ID                       0x0004  /* USB-4 */

/* commands
 * "INB": can be used on the in-band endpoint
 * "OOB": can be used on the out-of-band endpoint
 */
#define DIGI_CMD_SET_BAUD_RATE                  0       /* INB, OOB */
#define DIGI_CMD_SET_WORD_SIZE                  1       /* INB, OOB */
#define DIGI_CMD_SET_PARITY                     2       /* INB, OOB */
#define DIGI_CMD_SET_STOP_BITS                  3       /* INB, OOB */
#define DIGI_CMD_SET_INPUT_FLOW_CONTROL         4       /* INB, OOB */
#define DIGI_CMD_SET_OUTPUT_FLOW_CONTROL        5       /* INB, OOB */
#define DIGI_CMD_SET_DTR_SIGNAL                 6       /* INB, OOB */
#define DIGI_CMD_SET_RTS_SIGNAL                 7       /* INB, OOB */
#define DIGI_CMD_READ_INPUT_SIGNALS             8       /*      OOB */
#define DIGI_CMD_IFLUSH_FIFO                    9       /*      OOB */
#define DIGI_CMD_RECEIVE_ENABLE                 10      /* INB, OOB */
#define DIGI_CMD_BREAK_CONTROL                  11      /* INB, OOB */
#define DIGI_CMD_LOCAL_LOOPBACK                 12      /* INB, OOB */
#define DIGI_CMD_TRANSMIT_IDLE                  13      /* INB, OOB */
#define DIGI_CMD_READ_UART_REGISTER             14      /*      OOB */
#define DIGI_CMD_WRITE_UART_REGISTER            15      /* INB, OOB */
#define DIGI_CMD_AND_UART_REGISTER              16      /* INB, OOB */
#define DIGI_CMD_OR_UART_REGISTER               17      /* INB, OOB */
#define DIGI_CMD_SEND_DATA                      18      /* INB      */
#define DIGI_CMD_RECEIVE_DATA                   19      /* INB      */
#define DIGI_CMD_RECEIVE_DISABLE                20      /* INB      */
#define DIGI_CMD_GET_PORT_TYPE                  21      /*      OOB */

/* baud rates */
#define DIGI_BAUD_50                            0
#define DIGI_BAUD_75                            1
#define DIGI_BAUD_110                           2
#define DIGI_BAUD_150                           3
#define DIGI_BAUD_200                           4
#define DIGI_BAUD_300                           5
#define DIGI_BAUD_600                           6
#define DIGI_BAUD_1200                          7
#define DIGI_BAUD_1800                          8
#define DIGI_BAUD_2400                          9
#define DIGI_BAUD_4800                          10
#define DIGI_BAUD_7200                          11
#define DIGI_BAUD_9600                          12
#define DIGI_BAUD_14400                         13
#define DIGI_BAUD_19200                         14
#define DIGI_BAUD_28800                         15
#define DIGI_BAUD_38400                         16
#define DIGI_BAUD_57600                         17
#define DIGI_BAUD_76800                         18
#define DIGI_BAUD_115200                        19
#define DIGI_BAUD_153600                        20
#define DIGI_BAUD_230400                        21
#define DIGI_BAUD_460800                        22

/* arguments */
#define DIGI_WORD_SIZE_5                        0
#define DIGI_WORD_SIZE_6                        1
#define DIGI_WORD_SIZE_7                        2
#define DIGI_WORD_SIZE_8                        3

#define DIGI_PARITY_NONE                        0
#define DIGI_PARITY_ODD                         1
#define DIGI_PARITY_EVEN                        2
#define DIGI_PARITY_MARK                        3
#define DIGI_PARITY_SPACE                       4

#define DIGI_STOP_BITS_1                        0
#define DIGI_STOP_BITS_2                        1

#define DIGI_INPUT_FLOW_CONTROL_XON_XOFF        1
#define DIGI_INPUT_FLOW_CONTROL_RTS             2
#define DIGI_INPUT_FLOW_CONTROL_DTR             4

#define DIGI_OUTPUT_FLOW_CONTROL_XON_XOFF       1
#define DIGI_OUTPUT_FLOW_CONTROL_CTS            2
#define DIGI_OUTPUT_FLOW_CONTROL_DSR            4

#define DIGI_DTR_INACTIVE                       0
#define DIGI_DTR_ACTIVE                         1
#define DIGI_DTR_INPUT_FLOW_CONTROL             2

#define DIGI_RTS_INACTIVE                       0
#define DIGI_RTS_ACTIVE                         1
#define DIGI_RTS_INPUT_FLOW_CONTROL             2
#define DIGI_RTS_TOGGLE                         3

#define DIGI_FLUSH_TX                           1
#define DIGI_FLUSH_RX                           2
#define DIGI_RESUME_TX                          4 /* clears xoff condition */

#define DIGI_TRANSMIT_NOT_IDLE                  0
#define DIGI_TRANSMIT_IDLE                      1

#define DIGI_DISABLE                            0
#define DIGI_ENABLE                             1

#define DIGI_DEASSERT                           0
#define DIGI_ASSERT                             1

/* in band status codes */
#define DIGI_OVERRUN_ERROR                      4
#define DIGI_PARITY_ERROR                       8
#define DIGI_FRAMING_ERROR                      16
#define DIGI_BREAK_ERROR                        32

/* out of band status */
#define DIGI_NO_ERROR                           0
#define DIGI_BAD_FIRST_PARAMETER                1
#define DIGI_BAD_SECOND_PARAMETER               2
#define DIGI_INVALID_LINE                       3
#define DIGI_INVALID_OPCODE                     4

/* input signals */
#define DIGI_READ_INPUT_SIGNALS_SLOT            1
#define DIGI_READ_INPUT_SIGNALS_ERR             2
#define DIGI_READ_INPUT_SIGNALS_BUSY            4
#define DIGI_READ_INPUT_SIGNALS_PE              8
#define DIGI_READ_INPUT_SIGNALS_CTS             16
#define DIGI_READ_INPUT_SIGNALS_DSR             32
#define DIGI_READ_INPUT_SIGNALS_RI              64
#define DIGI_READ_INPUT_SIGNALS_DCD             128


/* Structures */

struct digi_serial {
        spinlock_t ds_serial_lock;
        struct usb_serial_port *ds_oob_port;    /* out-of-band port */
        int ds_oob_port_num;                    /* index of out-of-band port */
        int ds_device_started;
};

struct digi_port {
        spinlock_t dp_port_lock;
        int dp_port_num;
        int dp_out_buf_len;
        unsigned char dp_out_buf[DIGI_OUT_BUF_SIZE];
        int dp_in_buf_len;
        unsigned char dp_in_buf[DIGI_IN_BUF_SIZE];
        unsigned char dp_in_flag_buf[DIGI_IN_BUF_SIZE];
        int dp_write_urb_in_use;
        unsigned int dp_modem_signals;
        wait_queue_head_t dp_modem_change_wait;
        int dp_transmit_idle;
        wait_queue_head_t dp_transmit_idle_wait;
        int dp_throttled;
        int dp_throttle_restart;
        wait_queue_head_t dp_flush_wait;
        int dp_in_close;                        /* close in progress */
        wait_queue_head_t dp_close_wait;        /* wait queue for close */
        struct work_struct dp_wakeup_work;
};


/* Local Function Declarations */

static void digi_wakeup_write( struct usb_serial_port *port );
static void digi_wakeup_write_lock(void *);
static int digi_write_oob_command( struct usb_serial_port *port,
        unsigned char *buf, int count, int interruptible );
static int digi_write_inb_command( struct usb_serial_port *port,
        unsigned char *buf, int count, unsigned long timeout );
static int digi_set_modem_signals( struct usb_serial_port *port,
        unsigned int modem_signals, int interruptible );
static int digi_transmit_idle( struct usb_serial_port *port,
        unsigned long timeout );
static void digi_rx_throttle (struct usb_serial_port *port);
static void digi_rx_unthrottle (struct usb_serial_port *port);
static void digi_set_termios( struct usb_serial_port *port, 
        struct termios *old_termios );
static void digi_break_ctl( struct usb_serial_port *port, int break_state );
static int digi_ioctl( struct usb_serial_port *port, struct file *file,
        unsigned int cmd, unsigned long arg );
static int digi_tiocmget( struct usb_serial_port *port, struct file *file );
static int digi_tiocmset( struct usb_serial_port *port, struct file *file,
        unsigned int set, unsigned int clear );
static int digi_write( struct usb_serial_port *port, const unsigned char *buf, int count );
static void digi_write_bulk_callback( struct urb *urb, struct pt_regs *regs );
static int digi_write_room( struct usb_serial_port *port );
static int digi_chars_in_buffer( struct usb_serial_port *port );
static int digi_open( struct usb_serial_port *port, struct file *filp );
static void digi_close( struct usb_serial_port *port, struct file *filp );
static int digi_startup_device( struct usb_serial *serial );
static int digi_startup( struct usb_serial *serial );
static void digi_shutdown( struct usb_serial *serial );
static void digi_read_bulk_callback( struct urb *urb, struct pt_regs *regs );
static int digi_read_inb_callback( struct urb *urb );
static int digi_read_oob_callback( struct urb *urb );


/* Statics */

static int debug;

static struct usb_device_id id_table_combined [] = {
        { USB_DEVICE(DIGI_VENDOR_ID, DIGI_2_ID) },
        { USB_DEVICE(DIGI_VENDOR_ID, DIGI_4_ID) },
        { }                                             /* Terminating entry */
};

static struct usb_device_id id_table_2 [] = {
        { USB_DEVICE(DIGI_VENDOR_ID, DIGI_2_ID) },
        { }                                             /* Terminating entry */
};

static struct usb_device_id id_table_4 [] = {
        { USB_DEVICE(DIGI_VENDOR_ID, DIGI_4_ID) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, id_table_combined);

static struct usb_driver digi_driver = {
        .owner =        THIS_MODULE,
        .name =         "digi_acceleport",
        .probe =        usb_serial_probe,
        .disconnect =   usb_serial_disconnect,
        .id_table =     id_table_combined,
};


/* device info needed for the Digi serial converter */

static struct usb_serial_device_type digi_acceleport_2_device = {
        .owner =                        THIS_MODULE,
        .name =                         "Digi 2 port USB adapter",
        .short_name =                   "digi_2",
        .id_table =                     id_table_2,
        .num_interrupt_in =             0,
        .num_bulk_in =                  4,
        .num_bulk_out =                 4,
        .num_ports =                    3,
        .open =                         digi_open,
        .close =                        digi_close,
        .write =                        digi_write,
        .write_room =                   digi_write_room,
        .write_bulk_callback =          digi_write_bulk_callback,
        .read_bulk_callback =           digi_read_bulk_callback,
        .chars_in_buffer =              digi_chars_in_buffer,
        .throttle =                     digi_rx_throttle,
        .unthrottle =                   digi_rx_unthrottle,
        .ioctl =                        digi_ioctl,
        .set_termios =                  digi_set_termios,
        .break_ctl =                    digi_break_ctl,
        .tiocmget =                     digi_tiocmget,
        .tiocmset =                     digi_tiocmset,
        .attach =                       digi_startup,
        .shutdown =                     digi_shutdown,
};

static struct usb_serial_device_type digi_acceleport_4_device = {
        .owner =                        THIS_MODULE,
        .name =                         "Digi 4 port USB adapter",
        .short_name =                   "digi_4",
        .id_table =                     id_table_4,
        .num_interrupt_in =             0,
        .num_bulk_in =                  5,
        .num_bulk_out =                 5,
        .num_ports =                    4,
        .open =                         digi_open,
        .close =                        digi_close,
        .write =                        digi_write,
        .write_room =                   digi_write_room,
        .write_bulk_callback =          digi_write_bulk_callback,
        .read_bulk_callback =           digi_read_bulk_callback,
        .chars_in_buffer =              digi_chars_in_buffer,
        .throttle =                     digi_rx_throttle,
        .unthrottle =                   digi_rx_unthrottle,
        .ioctl =                        digi_ioctl,
        .set_termios =                  digi_set_termios,
        .break_ctl =                    digi_break_ctl,
        .tiocmget =                     digi_tiocmget,
        .tiocmset =                     digi_tiocmset,
        .attach =                       digi_startup,
        .shutdown =                     digi_shutdown,
};


/* Functions */

/*
*  Cond Wait Interruptible Timeout Irqrestore
*
*  Do spin_unlock_irqrestore and interruptible_sleep_on_timeout
*  so that wake ups are not lost if they occur between the unlock
*  and the sleep.  In other words, spin_unlock_irqrestore and
*  interruptible_sleep_on_timeout are "atomic" with respect to
*  wake ups.  This is used to implement condition variables.
*/

static inline long cond_wait_interruptible_timeout_irqrestore(
        wait_queue_head_t *q, long timeout,
        spinlock_t *lock, unsigned long flags )
{
        DEFINE_WAIT(wait);

        prepare_to_wait(q, &wait, TASK_UNINTERRUPTIBLE);
        spin_unlock_irqrestore(lock, flags);
        timeout = schedule_timeout(timeout);
        finish_wait(q, &wait);

        return timeout;

}


/*
*  Digi Wakeup Write
*
*  Wake up port, line discipline, and tty processes sleeping
*  on writes.
*/

static void digi_wakeup_write_lock(void *arg)
{
        struct usb_serial_port *port = arg;
        unsigned long flags;
        struct digi_port *priv = usb_get_serial_port_data(port);


        spin_lock_irqsave( &priv->dp_port_lock, flags );
        digi_wakeup_write( port );
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );
}

static void digi_wakeup_write( struct usb_serial_port *port )
{

        struct tty_struct *tty = port->tty;


        /* wake up port processes */
        wake_up_interruptible( &port->write_wait );

        /* wake up line discipline */
        tty_wakeup(tty);
}


/*
*  Digi Write OOB Command
*
*  Write commands on the out of band port.  Commands are 4
*  bytes each, multiple commands can be sent at once, and
*  no command will be split across USB packets.  Returns 0
*  if successful, -EINTR if interrupted while sleeping and
*  the interruptible flag is true, or a negative error
*  returned by usb_submit_urb.
*/

static int digi_write_oob_command( struct usb_serial_port *port,
        unsigned char *buf, int count, int interruptible )
{

        int ret = 0;
        int len;
        struct usb_serial_port *oob_port = (struct usb_serial_port *)((struct digi_serial *)(usb_get_serial_data(port->serial)))->ds_oob_port;
        struct digi_port *oob_priv = usb_get_serial_port_data(oob_port);
        unsigned long flags = 0;


dbg( "digi_write_oob_command: TOP: port=%d, count=%d", oob_priv->dp_port_num, count );

        spin_lock_irqsave( &oob_priv->dp_port_lock, flags );

        while( count > 0 ) {

                while( oob_port->write_urb->status == -EINPROGRESS
                || oob_priv->dp_write_urb_in_use ) {
                        cond_wait_interruptible_timeout_irqrestore(
                                &oob_port->write_wait, DIGI_RETRY_TIMEOUT,
                                &oob_priv->dp_port_lock, flags );
                        if( interruptible && signal_pending(current) ) {
                                return( -EINTR );
                        }
                        spin_lock_irqsave( &oob_priv->dp_port_lock, flags );
                }

                /* len must be a multiple of 4, so commands are not split */
                len = min(count, oob_port->bulk_out_size );
                if( len > 4 )
                        len &= ~3;

                memcpy( oob_port->write_urb->transfer_buffer, buf, len );
                oob_port->write_urb->transfer_buffer_length = len;
                oob_port->write_urb->dev = port->serial->dev;

                if( (ret=usb_submit_urb(oob_port->write_urb, GFP_ATOMIC)) == 0 ) {
                        oob_priv->dp_write_urb_in_use = 1;
                        count -= len;
                        buf += len;
                }

        }

        spin_unlock_irqrestore( &oob_priv->dp_port_lock, flags );

        if( ret ) {
                err("%s: usb_submit_urb failed, ret=%d", __FUNCTION__,
                        ret );
        }

        return( ret );

}


/*
*  Digi Write In Band Command
*
*  Write commands on the given port.  Commands are 4
*  bytes each, multiple commands can be sent at once, and
*  no command will be split across USB packets.  If timeout
*  is non-zero, write in band command will return after
*  waiting unsuccessfully for the URB status to clear for
*  timeout ticks.  Returns 0 if successful, or a negative
*  error returned by digi_write.
*/

static int digi_write_inb_command( struct usb_serial_port *port,
        unsigned char *buf, int count, unsigned long timeout )
{

        int ret = 0;
        int len;
        struct digi_port *priv = usb_get_serial_port_data(port);
        unsigned char *data = port->write_urb->transfer_buffer;
        unsigned long flags = 0;


dbg( "digi_write_inb_command: TOP: port=%d, count=%d", priv->dp_port_num,
count );

        if( timeout )
                timeout += jiffies;
        else
                timeout = ULONG_MAX;

        spin_lock_irqsave( &priv->dp_port_lock, flags );

        while( count > 0 && ret == 0 ) {

                while( (port->write_urb->status == -EINPROGRESS
                || priv->dp_write_urb_in_use) && time_before(jiffies, timeout)) {
                        cond_wait_interruptible_timeout_irqrestore(
                                &port->write_wait, DIGI_RETRY_TIMEOUT,
                                &priv->dp_port_lock, flags );
                        if( signal_pending(current) ) {
                                return( -EINTR );
                        }
                        spin_lock_irqsave( &priv->dp_port_lock, flags );
                }

                /* len must be a multiple of 4 and small enough to */
                /* guarantee the write will send buffered data first, */
                /* so commands are in order with data and not split */
                len = min(count, port->bulk_out_size-2-priv->dp_out_buf_len );
                if( len > 4 )
                        len &= ~3;

                /* write any buffered data first */
                if( priv->dp_out_buf_len > 0 ) {
                        data[0] = DIGI_CMD_SEND_DATA;
                        data[1] = priv->dp_out_buf_len;
                        memcpy( data+2, priv->dp_out_buf,
                                priv->dp_out_buf_len );
                        memcpy( data+2+priv->dp_out_buf_len, buf, len );
                        port->write_urb->transfer_buffer_length
                                = priv->dp_out_buf_len+2+len;
                } else {
                        memcpy( data, buf, len );
                        port->write_urb->transfer_buffer_length = len;
                }
                port->write_urb->dev = port->serial->dev;

                if( (ret=usb_submit_urb(port->write_urb, GFP_ATOMIC)) == 0 ) {
                        priv->dp_write_urb_in_use = 1;
                        priv->dp_out_buf_len = 0;
                        count -= len;
                        buf += len;
                }

        }

        spin_unlock_irqrestore( &priv->dp_port_lock, flags );

        if( ret ) {
                err("%s: usb_submit_urb failed, ret=%d, port=%d", __FUNCTION__,
                ret, priv->dp_port_num );
        }

        return( ret );

}


/*
*  Digi Set Modem Signals
*
*  Sets or clears DTR and RTS on the port, according to the
*  modem_signals argument.  Use TIOCM_DTR and TIOCM_RTS flags
*  for the modem_signals argument.  Returns 0 if successful,
*  -EINTR if interrupted while sleeping, or a non-zero error
*  returned by usb_submit_urb.
*/

static int digi_set_modem_signals( struct usb_serial_port *port,
        unsigned int modem_signals, int interruptible )
{

        int ret;
        struct digi_port *port_priv = usb_get_serial_port_data(port);
        struct usb_serial_port *oob_port = (struct usb_serial_port *)((struct digi_serial *)(usb_get_serial_data(port->serial)))->ds_oob_port;
        struct digi_port *oob_priv = usb_get_serial_port_data(oob_port);
        unsigned char *data = oob_port->write_urb->transfer_buffer;
        unsigned long flags = 0;


dbg( "digi_set_modem_signals: TOP: port=%d, modem_signals=0x%x",
port_priv->dp_port_num, modem_signals );

        spin_lock_irqsave( &oob_priv->dp_port_lock, flags );
        spin_lock( &port_priv->dp_port_lock );

        while( oob_port->write_urb->status == -EINPROGRESS
        || oob_priv->dp_write_urb_in_use ) {
                spin_unlock( &port_priv->dp_port_lock );
                cond_wait_interruptible_timeout_irqrestore(
                        &oob_port->write_wait, DIGI_RETRY_TIMEOUT,
                        &oob_priv->dp_port_lock, flags );
                if( interruptible && signal_pending(current) ) {
                        return( -EINTR );
                }
                spin_lock_irqsave( &oob_priv->dp_port_lock, flags );
                spin_lock( &port_priv->dp_port_lock );
        }

        data[0] = DIGI_CMD_SET_DTR_SIGNAL;
        data[1] = port_priv->dp_port_num;
        data[2] = (modem_signals&TIOCM_DTR) ?
                DIGI_DTR_ACTIVE : DIGI_DTR_INACTIVE;
        data[3] = 0;

        data[4] = DIGI_CMD_SET_RTS_SIGNAL;
        data[5] = port_priv->dp_port_num;
        data[6] = (modem_signals&TIOCM_RTS) ?
                DIGI_RTS_ACTIVE : DIGI_RTS_INACTIVE;
        data[7] = 0;

        oob_port->write_urb->transfer_buffer_length = 8;
        oob_port->write_urb->dev = port->serial->dev;

        if( (ret=usb_submit_urb(oob_port->write_urb, GFP_ATOMIC)) == 0 ) {
                oob_priv->dp_write_urb_in_use = 1;
                port_priv->dp_modem_signals =
                        (port_priv->dp_modem_signals&~(TIOCM_DTR|TIOCM_RTS))
                        | (modem_signals&(TIOCM_DTR|TIOCM_RTS));
        }

        spin_unlock( &port_priv->dp_port_lock );
        spin_unlock_irqrestore( &oob_priv->dp_port_lock, flags );

        if( ret ) {
                err("%s: usb_submit_urb failed, ret=%d", __FUNCTION__,
                ret );
        }

        return( ret );

}


/*
*  Digi Transmit Idle
*
*  Digi transmit idle waits, up to timeout ticks, for the transmitter
*  to go idle.  It returns 0 if successful or a negative error.
*
*  There are race conditions here if more than one process is calling
*  digi_transmit_idle on the same port at the same time.  However, this
*  is only called from close, and only one process can be in close on a
*  port at a time, so its ok.
*/

static int digi_transmit_idle( struct usb_serial_port *port,
        unsigned long timeout )
{

        int ret;
        unsigned char buf[2];
        struct digi_port *priv = usb_get_serial_port_data(port);
        unsigned long flags = 0;


        spin_lock_irqsave( &priv->dp_port_lock, flags );
        priv->dp_transmit_idle = 0;
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );

        buf[0] = DIGI_CMD_TRANSMIT_IDLE;
        buf[1] = 0;

        timeout += jiffies;

        if( (ret=digi_write_inb_command( port, buf, 2, timeout-jiffies )) != 0 )
                return( ret );

        spin_lock_irqsave( &priv->dp_port_lock, flags );

        while( time_before(jiffies, timeout) && !priv->dp_transmit_idle ) {
                cond_wait_interruptible_timeout_irqrestore(
                        &priv->dp_transmit_idle_wait, DIGI_RETRY_TIMEOUT,
                        &priv->dp_port_lock, flags );
                if( signal_pending(current) ) {
                        return( -EINTR );
                }
                spin_lock_irqsave( &priv->dp_port_lock, flags );
        }

        priv->dp_transmit_idle = 0;
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );

        return( 0 );

}


static void digi_rx_throttle( struct usb_serial_port *port )
{

        unsigned long flags;
        struct digi_port *priv = usb_get_serial_port_data(port);


dbg( "digi_rx_throttle: TOP: port=%d", priv->dp_port_num );

        /* stop receiving characters by not resubmitting the read urb */
        spin_lock_irqsave( &priv->dp_port_lock, flags );
        priv->dp_throttled = 1;
        priv->dp_throttle_restart = 0;
        priv->dp_in_buf_len = 0;
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );

}


static void digi_rx_unthrottle( struct usb_serial_port *port )
{

        int ret = 0;
        int len;
        unsigned long flags;
        struct digi_port *priv = usb_get_serial_port_data(port);
        struct tty_struct *tty = port->tty;


dbg( "digi_rx_unthrottle: TOP: port=%d", priv->dp_port_num );

        spin_lock_irqsave( &priv->dp_port_lock, flags );

        /* send any buffered chars from throttle time on to tty subsystem */
        len = min(priv->dp_in_buf_len, TTY_FLIPBUF_SIZE - tty->flip.count );
        if( len > 0 ) {
                memcpy( tty->flip.char_buf_ptr, priv->dp_in_buf, len );
                memcpy( tty->flip.flag_buf_ptr, priv->dp_in_flag_buf, len );
                tty->flip.char_buf_ptr += len;
                tty->flip.flag_buf_ptr += len;
                tty->flip.count += len;
                tty_flip_buffer_push( tty );
        }

        /* restart read chain */
        if( priv->dp_throttle_restart ) {
                port->read_urb->dev = port->serial->dev;
                ret = usb_submit_urb( port->read_urb, GFP_ATOMIC );
        }

        /* turn throttle off */
        priv->dp_throttled = 0;
        priv->dp_in_buf_len = 0;
        priv->dp_throttle_restart = 0;

        spin_unlock_irqrestore( &priv->dp_port_lock, flags );

        if( ret ) {
                err("%s: usb_submit_urb failed, ret=%d, port=%d", __FUNCTION__,
                        ret, priv->dp_port_num );
        }

}


static void digi_set_termios( struct usb_serial_port *port, 
        struct termios *old_termios )
{

        struct digi_port *priv = usb_get_serial_port_data(port);
        unsigned int iflag = port->tty->termios->c_iflag;
        unsigned int cflag = port->tty->termios->c_cflag;
        unsigned int old_iflag = old_termios->c_iflag;
        unsigned int old_cflag = old_termios->c_cflag;
        unsigned char buf[32];
        unsigned int modem_signals;
        int arg,ret;
        int i = 0;


dbg( "digi_set_termios: TOP: port=%d, iflag=0x%x, old_iflag=0x%x, cflag=0x%x, old_cflag=0x%x", priv->dp_port_num, iflag, old_iflag, cflag, old_cflag );

        /* set baud rate */
        if( (cflag&CBAUD) != (old_cflag&CBAUD) ) {

                arg = -1;

                /* reassert DTR and (maybe) RTS on transition from B0 */
                if( (old_cflag&CBAUD) == B0 ) {
                        /* don't set RTS if using hardware flow control */
                        /* and throttling input */
                        modem_signals = TIOCM_DTR;
                        if( !(port->tty->termios->c_cflag & CRTSCTS) ||
                        !test_bit(TTY_THROTTLED, &port->tty->flags) ) {
                                modem_signals |= TIOCM_RTS;
                        }
                        digi_set_modem_signals( port, modem_signals, 1 );
                }

                switch( (cflag&CBAUD) ) {
                        /* drop DTR and RTS on transition to B0 */
                case B0: digi_set_modem_signals( port, 0, 1 ); break;
                case B50: arg = DIGI_BAUD_50; break;
                case B75: arg = DIGI_BAUD_75; break;
                case B110: arg = DIGI_BAUD_110; break;
                case B150: arg = DIGI_BAUD_150; break;
                case B200: arg = DIGI_BAUD_200; break;
                case B300: arg = DIGI_BAUD_300; break;
                case B600: arg = DIGI_BAUD_600; break;
                case B1200: arg = DIGI_BAUD_1200; break;
                case B1800: arg = DIGI_BAUD_1800; break;
                case B2400: arg = DIGI_BAUD_2400; break;
                case B4800: arg = DIGI_BAUD_4800; break;
                case B9600: arg = DIGI_BAUD_9600; break;
                case B19200: arg = DIGI_BAUD_19200; break;
                case B38400: arg = DIGI_BAUD_38400; break;
                case B57600: arg = DIGI_BAUD_57600; break;
                case B115200: arg = DIGI_BAUD_115200; break;
                case B230400: arg = DIGI_BAUD_230400; break;
                case B460800: arg = DIGI_BAUD_460800; break;
                default:
                        dbg( "digi_set_termios: can't handle baud rate 0x%x",
                                (cflag&CBAUD) );
                        break;
                }

                if( arg != -1 ) {
                        buf[i++] = DIGI_CMD_SET_BAUD_RATE;
                        buf[i++] = priv->dp_port_num;
                        buf[i++] = arg;
                        buf[i++] = 0;
                }

        }

        /* set parity */
        if( (cflag&(PARENB|PARODD)) != (old_cflag&(PARENB|PARODD)) ) {

                if( (cflag&PARENB) ) {
                        if( (cflag&PARODD) )
                                arg = DIGI_PARITY_ODD;
                        else
                                arg = DIGI_PARITY_EVEN;
                } else {
                        arg = DIGI_PARITY_NONE;
                }

                buf[i++] = DIGI_CMD_SET_PARITY;
                buf[i++] = priv->dp_port_num;
                buf[i++] = arg;
                buf[i++] = 0;

        }

        /* set word size */
        if( (cflag&CSIZE) != (old_cflag&CSIZE) ) {

                arg = -1;

                switch( (cflag&CSIZE) ) {
                case CS5: arg = DIGI_WORD_SIZE_5; break;
                case CS6: arg = DIGI_WORD_SIZE_6; break;
                case CS7: arg = DIGI_WORD_SIZE_7; break;
                case CS8: arg = DIGI_WORD_SIZE_8; break;
                default:
                        dbg( "digi_set_termios: can't handle word size %d",
                                (cflag&CSIZE) );
                        break;
                }

                if( arg != -1 ) {
                        buf[i++] = DIGI_CMD_SET_WORD_SIZE;
                        buf[i++] = priv->dp_port_num;
                        buf[i++] = arg;
                        buf[i++] = 0;
                }

        }

        /* set stop bits */
        if( (cflag&CSTOPB) != (old_cflag&CSTOPB) ) {

                if( (cflag&CSTOPB) )
                        arg = DIGI_STOP_BITS_2;
                else
                        arg = DIGI_STOP_BITS_1;

                buf[i++] = DIGI_CMD_SET_STOP_BITS;
                buf[i++] = priv->dp_port_num;
                buf[i++] = arg;
                buf[i++] = 0;

        }

        /* set input flow control */
        if( (iflag&IXOFF) != (old_iflag&IXOFF)
        || (cflag&CRTSCTS) != (old_cflag&CRTSCTS) ) {

                arg = 0;

                if( (iflag&IXOFF) )
                        arg |= DIGI_INPUT_FLOW_CONTROL_XON_XOFF;
                else
                        arg &= ~DIGI_INPUT_FLOW_CONTROL_XON_XOFF;

                if( (cflag&CRTSCTS) ) {

                        arg |= DIGI_INPUT_FLOW_CONTROL_RTS;

                        /* On USB-4 it is necessary to assert RTS prior */
                        /* to selecting RTS input flow control.  */
                        buf[i++] = DIGI_CMD_SET_RTS_SIGNAL;
                        buf[i++] = priv->dp_port_num;
                        buf[i++] = DIGI_RTS_ACTIVE;
                        buf[i++] = 0;

                } else {
                        arg &= ~DIGI_INPUT_FLOW_CONTROL_RTS;
                }

                buf[i++] = DIGI_CMD_SET_INPUT_FLOW_CONTROL;
                buf[i++] = priv->dp_port_num;
                buf[i++] = arg;
                buf[i++] = 0;

        }

        /* set output flow control */
        if( (iflag&IXON) != (old_iflag&IXON)
        || (cflag&CRTSCTS) != (old_cflag&CRTSCTS) ) {

                arg = 0;

                if( (iflag&IXON) )
                        arg |= DIGI_OUTPUT_FLOW_CONTROL_XON_XOFF;
                else
                        arg &= ~DIGI_OUTPUT_FLOW_CONTROL_XON_XOFF;

                if( (cflag&CRTSCTS) ) {
                        arg |= DIGI_OUTPUT_FLOW_CONTROL_CTS;
                } else {
                        arg &= ~DIGI_OUTPUT_FLOW_CONTROL_CTS;
                        port->tty->hw_stopped = 0;
                }

                buf[i++] = DIGI_CMD_SET_OUTPUT_FLOW_CONTROL;
                buf[i++] = priv->dp_port_num;
                buf[i++] = arg;
                buf[i++] = 0;

        }

        /* set receive enable/disable */
        if( (cflag&CREAD) != (old_cflag&CREAD) ) {

                if( (cflag&CREAD) )
                        arg = DIGI_ENABLE;
                else
                        arg = DIGI_DISABLE;

                buf[i++] = DIGI_CMD_RECEIVE_ENABLE;
                buf[i++] = priv->dp_port_num;
                buf[i++] = arg;
                buf[i++] = 0;

        }

        if( (ret=digi_write_oob_command( port, buf, i, 1 )) != 0 )
                dbg( "digi_set_termios: write oob failed, ret=%d", ret );

}


static void digi_break_ctl( struct usb_serial_port *port, int break_state )
{

        unsigned char buf[4];


        buf[0] = DIGI_CMD_BREAK_CONTROL;
        buf[1] = 2;                             /* length */
        buf[2] = break_state ? 1 : 0;
        buf[3] = 0;                             /* pad */

        digi_write_inb_command( port, buf, 4, 0 );

}


static int digi_tiocmget( struct usb_serial_port *port, struct file *file )
{
        struct digi_port *priv = usb_get_serial_port_data(port);
        unsigned int val;
        unsigned long flags;

        dbg("%s: TOP: port=%d", __FUNCTION__, priv->dp_port_num);

        spin_lock_irqsave( &priv->dp_port_lock, flags );
        val = priv->dp_modem_signals;
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );
        return val;
}


static int digi_tiocmset( struct usb_serial_port *port, struct file *file,
        unsigned int set, unsigned int clear )
{
        struct digi_port *priv = usb_get_serial_port_data(port);
        unsigned int val;
        unsigned long flags;

        dbg("%s: TOP: port=%d", __FUNCTION__, priv->dp_port_num);

        spin_lock_irqsave( &priv->dp_port_lock, flags );
        val = (priv->dp_modem_signals & ~clear) | set;
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );
        return digi_set_modem_signals( port, val, 1 );
}


static int digi_ioctl( struct usb_serial_port *port, struct file *file,
        unsigned int cmd, unsigned long arg )
{

        struct digi_port *priv = usb_get_serial_port_data(port);

dbg( "digi_ioctl: TOP: port=%d, cmd=0x%x", priv->dp_port_num, cmd );

        switch (cmd) {

        case TIOCMIWAIT:
                /* wait for any of the 4 modem inputs (DCD,RI,DSR,CTS)*/
                /* TODO */
                return( 0 );

        case TIOCGICOUNT:
                /* return count of modemline transitions */
                /* TODO */
                return 0;

        }

        return( -ENOIOCTLCMD );

}


static int digi_write( struct usb_serial_port *port, const unsigned char *buf, int count )
{

        int ret,data_len,new_len;
        struct digi_port *priv = usb_get_serial_port_data(port);
        unsigned char *data = port->write_urb->transfer_buffer;
        unsigned long flags = 0;


dbg( "digi_write: TOP: port=%d, count=%d, in_interrupt=%ld",
priv->dp_port_num, count, in_interrupt() );

        /* copy user data (which can sleep) before getting spin lock */
        count = min( count, port->bulk_out_size-2 );
        count = min( 64, count);

        /* be sure only one write proceeds at a time */
        /* there are races on the port private buffer */
        /* and races to check write_urb->status */
        spin_lock_irqsave( &priv->dp_port_lock, flags );

        /* wait for urb status clear to submit another urb */
        if( port->write_urb->status == -EINPROGRESS
        || priv->dp_write_urb_in_use ) {

                /* buffer data if count is 1 (probably put_char) if possible */
                if( count == 1 && priv->dp_out_buf_len < DIGI_OUT_BUF_SIZE ) {
                        priv->dp_out_buf[priv->dp_out_buf_len++] = *buf;
                        new_len = 1;
                } else {
                        new_len = 0;
                }

                spin_unlock_irqrestore( &priv->dp_port_lock, flags );

                return( new_len );

        }

        /* allow space for any buffered data and for new data, up to */
        /* transfer buffer size - 2 (for command and length bytes) */
        new_len = min(count, port->bulk_out_size-2-priv->dp_out_buf_len);
        data_len = new_len + priv->dp_out_buf_len;

        if( data_len == 0 ) {
                spin_unlock_irqrestore( &priv->dp_port_lock, flags );
                return( 0 );
        }

        port->write_urb->transfer_buffer_length = data_len+2;
        port->write_urb->dev = port->serial->dev;

        *data++ = DIGI_CMD_SEND_DATA;
        *data++ = data_len;

        /* copy in buffered data first */
        memcpy( data, priv->dp_out_buf, priv->dp_out_buf_len );
        data += priv->dp_out_buf_len;

        /* copy in new data */
        memcpy( data, buf, new_len );

        if( (ret=usb_submit_urb(port->write_urb, GFP_ATOMIC)) == 0 ) {
                priv->dp_write_urb_in_use = 1;
                ret = new_len;
                priv->dp_out_buf_len = 0;
        }

        /* return length of new data written, or error */
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );
        if( ret < 0 ) {
                err("%s: usb_submit_urb failed, ret=%d, port=%d", __FUNCTION__,
                        ret, priv->dp_port_num );
        }

dbg( "digi_write: returning %d", ret );
        return( ret );

} 


static void digi_write_bulk_callback( struct urb *urb, struct pt_regs *regs )
{

        struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
        struct usb_serial *serial;
        struct digi_port *priv;
        struct digi_serial *serial_priv;
        int ret = 0;


dbg( "digi_write_bulk_callback: TOP, urb->status=%d", urb->status );

        /* port and serial sanity check */
        if( port == NULL || (priv=usb_get_serial_port_data(port)) == NULL ) {
                err("%s: port or port->private is NULL, status=%d", __FUNCTION__,
                        urb->status );
                return;
        }
        serial = port->serial;
        if( serial == NULL || (serial_priv=usb_get_serial_data(serial)) == NULL ) {
                err("%s: serial or serial->private is NULL, status=%d", __FUNCTION__, urb->status );
                return;
        }

        /* handle oob callback */
        if( priv->dp_port_num == serial_priv->ds_oob_port_num ) {
                dbg( "digi_write_bulk_callback: oob callback" );
                spin_lock( &priv->dp_port_lock );
                priv->dp_write_urb_in_use = 0;
                wake_up_interruptible( &port->write_wait );
                spin_unlock( &priv->dp_port_lock );
                return;
        }

        /* try to send any buffered data on this port, if it is open */
        spin_lock( &priv->dp_port_lock );
        priv->dp_write_urb_in_use = 0;
        if( port->open_count && port->write_urb->status != -EINPROGRESS
        && priv->dp_out_buf_len > 0 ) {

                *((unsigned char *)(port->write_urb->transfer_buffer))
                        = (unsigned char)DIGI_CMD_SEND_DATA;
                *((unsigned char *)(port->write_urb->transfer_buffer)+1)
                        = (unsigned char)priv->dp_out_buf_len;

                port->write_urb->transfer_buffer_length
                        = priv->dp_out_buf_len+2;
                port->write_urb->dev = serial->dev;

                memcpy( port->write_urb->transfer_buffer+2, priv->dp_out_buf,
                        priv->dp_out_buf_len );

                if( (ret=usb_submit_urb(port->write_urb, GFP_ATOMIC)) == 0 ) {
                        priv->dp_write_urb_in_use = 1;
                        priv->dp_out_buf_len = 0;
                }

        }

        /* wake up processes sleeping on writes immediately */
        digi_wakeup_write( port );

        /* also queue up a wakeup at scheduler time, in case we */
        /* lost the race in write_chan(). */
        schedule_work(&priv->dp_wakeup_work);

        spin_unlock( &priv->dp_port_lock );

        if( ret ) {
                err("%s: usb_submit_urb failed, ret=%d, port=%d", __FUNCTION__,
                        ret, priv->dp_port_num );
        }

}


static int digi_write_room( struct usb_serial_port *port )
{

        int room;
        struct digi_port *priv = usb_get_serial_port_data(port);
        unsigned long flags = 0;


        spin_lock_irqsave( &priv->dp_port_lock, flags );

        if( port->write_urb->status == -EINPROGRESS
        || priv->dp_write_urb_in_use )
                room = 0;
        else
                room = port->bulk_out_size - 2 - priv->dp_out_buf_len;

        spin_unlock_irqrestore( &priv->dp_port_lock, flags );

dbg( "digi_write_room: port=%d, room=%d", priv->dp_port_num, room );
        return( room );

}


static int digi_chars_in_buffer( struct usb_serial_port *port )
{

        struct digi_port *priv = usb_get_serial_port_data(port);


        if( port->write_urb->status == -EINPROGRESS
        || priv->dp_write_urb_in_use ) {
dbg( "digi_chars_in_buffer: port=%d, chars=%d", priv->dp_port_num, port->bulk_out_size - 2 );
                /* return( port->bulk_out_size - 2 ); */
                return( 256 );
        } else {
dbg( "digi_chars_in_buffer: port=%d, chars=%d", priv->dp_port_num, priv->dp_out_buf_len );
                return( priv->dp_out_buf_len );
        }

}


static int digi_open( struct usb_serial_port *port, struct file *filp )
{

        int ret;
        unsigned char buf[32];
        struct digi_port *priv = usb_get_serial_port_data(port);
        struct termios not_termios;
        unsigned long flags = 0;


dbg( "digi_open: TOP: port=%d, open_count=%d", priv->dp_port_num, port->open_count );

        /* be sure the device is started up */
        if( digi_startup_device( port->serial ) != 0 )
                return( -ENXIO );

        spin_lock_irqsave( &priv->dp_port_lock, flags );

        /* don't wait on a close in progress for non-blocking opens */
        if( priv->dp_in_close && (filp->f_flags&(O_NDELAY|O_NONBLOCK)) == 0 ) {
                spin_unlock_irqrestore( &priv->dp_port_lock, flags );
                return( -EAGAIN );
        }

        /* wait for a close in progress to finish */
        while( priv->dp_in_close ) {
                cond_wait_interruptible_timeout_irqrestore(
                        &priv->dp_close_wait, DIGI_RETRY_TIMEOUT,
                        &priv->dp_port_lock, flags );
                if( signal_pending(current) ) {
                        return( -EINTR );
                }
                spin_lock_irqsave( &priv->dp_port_lock, flags );
        }

        spin_unlock_irqrestore( &priv->dp_port_lock, flags );
 
        /* read modem signals automatically whenever they change */
        buf[0] = DIGI_CMD_READ_INPUT_SIGNALS;
        buf[1] = priv->dp_port_num;
        buf[2] = DIGI_ENABLE;
        buf[3] = 0;

        /* flush fifos */
        buf[4] = DIGI_CMD_IFLUSH_FIFO;
        buf[5] = priv->dp_port_num;
        buf[6] = DIGI_FLUSH_TX | DIGI_FLUSH_RX;
        buf[7] = 0;

        if( (ret=digi_write_oob_command( port, buf, 8, 1 )) != 0 )
                dbg( "digi_open: write oob failed, ret=%d", ret );

        /* set termios settings */
        not_termios.c_cflag = ~port->tty->termios->c_cflag;
        not_termios.c_iflag = ~port->tty->termios->c_iflag;
        digi_set_termios( port, &not_termios );

        /* set DTR and RTS */
        digi_set_modem_signals( port, TIOCM_DTR|TIOCM_RTS, 1 );

        return( 0 );

}


static void digi_close( struct usb_serial_port *port, struct file *filp )
{
        DEFINE_WAIT(wait);
        int ret;
        unsigned char buf[32];
        struct tty_struct *tty = port->tty;
        struct digi_port *priv = usb_get_serial_port_data(port);
        unsigned long flags = 0;


dbg( "digi_close: TOP: port=%d, open_count=%d", priv->dp_port_num, port->open_count );


        /* if disconnected, just clear flags */
        if (!usb_get_intfdata(port->serial->interface))
                goto exit;

        /* do cleanup only after final close on this port */
        spin_lock_irqsave( &priv->dp_port_lock, flags );
        priv->dp_in_close = 1;
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );

        /* tell line discipline to process only XON/XOFF */
        tty->closing = 1;

        /* wait for output to drain */
        if( (filp->f_flags&(O_NDELAY|O_NONBLOCK)) == 0 ) {
                tty_wait_until_sent( tty, DIGI_CLOSE_TIMEOUT );
        }

        /* flush driver and line discipline buffers */
        if( tty->driver->flush_buffer )
                tty->driver->flush_buffer( tty );
        tty_ldisc_flush(tty);

        if (port->serial->dev) {
                /* wait for transmit idle */
                if( (filp->f_flags&(O_NDELAY|O_NONBLOCK)) == 0 ) {
                        digi_transmit_idle( port, DIGI_CLOSE_TIMEOUT );
                }

                /* drop DTR and RTS */
                digi_set_modem_signals( port, 0, 0 );

                /* disable input flow control */
                buf[0] = DIGI_CMD_SET_INPUT_FLOW_CONTROL;
                buf[1] = priv->dp_port_num;
                buf[2] = DIGI_DISABLE;
                buf[3] = 0;

                /* disable output flow control */
                buf[4] = DIGI_CMD_SET_OUTPUT_FLOW_CONTROL;
                buf[5] = priv->dp_port_num;
                buf[6] = DIGI_DISABLE;
                buf[7] = 0;

                /* disable reading modem signals automatically */
                buf[8] = DIGI_CMD_READ_INPUT_SIGNALS;
                buf[9] = priv->dp_port_num;
                buf[10] = DIGI_DISABLE;
                buf[11] = 0;

                /* disable receive */
                buf[12] = DIGI_CMD_RECEIVE_ENABLE;
                buf[13] = priv->dp_port_num;
                buf[14] = DIGI_DISABLE;
                buf[15] = 0;

                /* flush fifos */
                buf[16] = DIGI_CMD_IFLUSH_FIFO;
                buf[17] = priv->dp_port_num;
                buf[18] = DIGI_FLUSH_TX | DIGI_FLUSH_RX;
                buf[19] = 0;

                if( (ret=digi_write_oob_command( port, buf, 20, 0 )) != 0 )
                        dbg( "digi_close: write oob failed, ret=%d", ret );

                /* wait for final commands on oob port to complete */
                prepare_to_wait(&priv->dp_flush_wait, &wait, TASK_UNINTERRUPTIBLE);
                schedule_timeout(DIGI_CLOSE_TIMEOUT);
                finish_wait(&priv->dp_flush_wait, &wait);

                /* shutdown any outstanding bulk writes */
                usb_kill_urb(port->write_urb);
        }

        tty->closing = 0;

exit:
        spin_lock_irqsave( &priv->dp_port_lock, flags );
        priv->dp_write_urb_in_use = 0;
        priv->dp_in_close = 0;
        wake_up_interruptible( &priv->dp_close_wait );
        spin_unlock_irqrestore( &priv->dp_port_lock, flags );

dbg( "digi_close: done" );
}


/*
*  Digi Startup Device
*
*  Starts reads on all ports.  Must be called AFTER startup, with
*  urbs initialized.  Returns 0 if successful, non-zero error otherwise.
*/

static int digi_startup_device( struct usb_serial *serial )
{

        int i,ret = 0;
        struct digi_serial *serial_priv = usb_get_serial_data(serial);
        struct usb_serial_port *port;


        /* be sure this happens exactly once */
        spin_lock( &serial_priv->ds_serial_lock );
        if( serial_priv->ds_device_started ) {
                spin_unlock( &serial_priv->ds_serial_lock );
                return( 0 );
        }
        serial_priv->ds_device_started = 1;
        spin_unlock( &serial_priv->ds_serial_lock );

        /* start reading from each bulk in endpoint for the device */
        /* set USB_DISABLE_SPD flag for write bulk urbs */
        for( i=0; i<serial->type->num_ports+1; i++ ) {

                port = serial->port[i];

                port->write_urb->dev = port->serial->dev;

                if( (ret=usb_submit_urb(port->read_urb, GFP_KERNEL)) != 0 ) {
                        err("%s: usb_submit_urb failed, ret=%d, port=%d", __FUNCTION__,
                        ret, i );
                        break;
                }

        }

        return( ret );

}


static int digi_startup( struct usb_serial *serial )
{

        int i;
        struct digi_port *priv;
        struct digi_serial *serial_priv;


dbg( "digi_startup: TOP" );

        /* allocate the private data structures for all ports */
        /* number of regular ports + 1 for the out-of-band port */
        for( i=0; i<serial->type->num_ports+1; i++ ) {

                /* allocate port private structure */
                priv = (struct digi_port *)kmalloc( sizeof(struct digi_port),
                        GFP_KERNEL );
                if( priv == (struct digi_port *)0 ) {
                        while( --i >= 0 )
                                kfree( usb_get_serial_port_data(serial->port[i]) );
                        return( 1 );                    /* error */
                }

                /* initialize port private structure */
                spin_lock_init( &priv->dp_port_lock );
                priv->dp_port_num = i;
                priv->dp_out_buf_len = 0;
                priv->dp_in_buf_len = 0;
                priv->dp_write_urb_in_use = 0;
                priv->dp_modem_signals = 0;
                init_waitqueue_head( &priv->dp_modem_change_wait );
                priv->dp_transmit_idle = 0;
                init_waitqueue_head( &priv->dp_transmit_idle_wait );
                priv->dp_throttled = 0;
                priv->dp_throttle_restart = 0;
                init_waitqueue_head( &priv->dp_flush_wait );
                priv->dp_in_close = 0;
                init_waitqueue_head( &priv->dp_close_wait );
                INIT_WORK(&priv->dp_wakeup_work,
                                digi_wakeup_write_lock, serial->port[i]);

                /* initialize write wait queue for this port */
                init_waitqueue_head( &serial->port[i]->write_wait );

                usb_set_serial_port_data(serial->port[i], priv);
        }

        /* allocate serial private structure */
        serial_priv = (struct digi_serial *)kmalloc( sizeof(struct digi_serial),
                GFP_KERNEL );
        if( serial_priv == (struct digi_serial *)0 ) {
                for( i=0; i<serial->type->num_ports+1; i++ )
                        kfree( usb_get_serial_port_data(serial->port[i]) );
                return( 1 );                    /* error */
        }

        /* initialize serial private structure */
        spin_lock_init( &serial_priv->ds_serial_lock );
        serial_priv->ds_oob_port_num = serial->type->num_ports;
        serial_priv->ds_oob_port = serial->port[serial_priv->ds_oob_port_num];
        serial_priv->ds_device_started = 0;
        usb_set_serial_data(serial, serial_priv);

        return( 0 );

}


static void digi_shutdown( struct usb_serial *serial )
{

        int i;


dbg( "digi_shutdown: TOP, in_interrupt()=%ld", in_interrupt() );

        /* stop reads and writes on all ports */
        for( i=0; i<serial->type->num_ports+1; i++ ) {
                usb_kill_urb(serial->port[i]->read_urb);
                usb_kill_urb(serial->port[i]->write_urb);
        }

        /* free the private data structures for all ports */
        /* number of regular ports + 1 for the out-of-band port */
        for( i=0; i<serial->type->num_ports+1; i++ )
                kfree( usb_get_serial_port_data(serial->port[i]) );
        kfree( usb_get_serial_data(serial) );
}


static void digi_read_bulk_callback( struct urb *urb, struct pt_regs *regs )
{

        struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
        struct digi_port *priv;
        struct digi_serial *serial_priv;
        int ret;


dbg( "digi_read_bulk_callback: TOP" );

        /* port sanity check, do not resubmit if port is not valid */
        if( port == NULL || (priv=usb_get_serial_port_data(port)) == NULL ) {
                err("%s: port or port->private is NULL, status=%d", __FUNCTION__,
                        urb->status );
                return;
        }
        if( port->serial == NULL
        || (serial_priv=usb_get_serial_data(port->serial)) == NULL ) {
                err("%s: serial is bad or serial->private is NULL, status=%d", __FUNCTION__, urb->status );
                return;
        }

        /* do not resubmit urb if it has any status error */
        if( urb->status ) {
                err("%s: nonzero read bulk status: status=%d, port=%d", __FUNCTION__, urb->status, priv->dp_port_num );
                return;
        }

        /* handle oob or inb callback, do not resubmit if error */
        if( priv->dp_port_num == serial_priv->ds_oob_port_num ) {
                if( digi_read_oob_callback( urb ) != 0 )
                        return;
        } else {
                if( digi_read_inb_callback( urb ) != 0 )
                        return;
        }

        /* continue read */
        urb->dev = port->serial->dev;
        if( (ret=usb_submit_urb(urb, GFP_ATOMIC)) != 0 ) {
                err("%s: failed resubmitting urb, ret=%d, port=%d", __FUNCTION__,
                        ret, priv->dp_port_num );
        }

}


/* 
*  Digi Read INB Callback
*
*  Digi Read INB Callback handles reads on the in band ports, sending
*  the data on to the tty subsystem.  When called we know port and
*  port->private are not NULL and port->serial has been validated.
*  It returns 0 if successful, 1 if successful but the port is
*  throttled, and -1 if the sanity checks failed.
*/

static int digi_read_inb_callback( struct urb *urb )
{

        struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
        struct tty_struct *tty = port->tty;
        struct digi_port *priv = usb_get_serial_port_data(port);
        int opcode = ((unsigned char *)urb->transfer_buffer)[0];
        int len = ((unsigned char *)urb->transfer_buffer)[1];
        int status = ((unsigned char *)urb->transfer_buffer)[2];
        unsigned char *data = ((unsigned char *)urb->transfer_buffer)+3;
        int flag,throttled;

        /* do not process callbacks on closed ports */
        /* but do continue the read chain */
        if( port->open_count == 0 )
                return( 0 );

        /* short/multiple packet check */
        if( urb->actual_length != len + 2 ) {
                err("%s: INCOMPLETE OR MULTIPLE PACKET, urb->status=%d, port=%d, opcode=%d, len=%d, actual_length=%d, status=%d", __FUNCTION__, urb->status, priv->dp_port_num, opcode, len, urb->actual_length, status );
                return( -1 );
        }

        spin_lock( &priv->dp_port_lock );

        /* check for throttle; if set, do not resubmit read urb */
        /* indicate the read chain needs to be restarted on unthrottle */
        throttled = priv->dp_throttled;
        if( throttled )
                priv->dp_throttle_restart = 1;

        /* receive data */
        if( opcode == DIGI_CMD_RECEIVE_DATA ) {

                /* get flag from status */
                flag = 0;

                /* overrun is special, not associated with a char */
                if( status & DIGI_OVERRUN_ERROR ) {
                        tty_insert_flip_char( tty, 0, TTY_OVERRUN );
                }

                /* break takes precedence over parity, */
                /* which takes precedence over framing errors */
                if( status & DIGI_BREAK_ERROR ) {
                        flag = TTY_BREAK;
                } else if( status & DIGI_PARITY_ERROR ) {
                        flag = TTY_PARITY;
                } else if( status & DIGI_FRAMING_ERROR ) {
                        flag = TTY_FRAME;
                }

                /* data length is len-1 (one byte of len is status) */
                --len;

                if( throttled ) {

                        len = min( len,
                                DIGI_IN_BUF_SIZE - priv->dp_in_buf_len );

                        if( len > 0 ) {
                                memcpy( priv->dp_in_buf + priv->dp_in_buf_len,
                                        data, len );
                                memset( priv->dp_in_flag_buf
                                        + priv->dp_in_buf_len, flag, len );
                                priv->dp_in_buf_len += len;
                        }

                } else {

                        len = min( len, TTY_FLIPBUF_SIZE - tty->flip.count );

                        if( len > 0 ) {
                                memcpy( tty->flip.char_buf_ptr, data, len );
                                memset( tty->flip.flag_buf_ptr, flag, len );
                                tty->flip.char_buf_ptr += len;
                                tty->flip.flag_buf_ptr += len;
                                tty->flip.count += len;
                                tty_flip_buffer_push( tty );
                        }

                }

        }

        spin_unlock( &priv->dp_port_lock );

        if( opcode == DIGI_CMD_RECEIVE_DISABLE ) {
                dbg("%s: got RECEIVE_DISABLE", __FUNCTION__ );
        } else if( opcode != DIGI_CMD_RECEIVE_DATA ) {
                dbg("%s: unknown opcode: %d", __FUNCTION__, opcode );
        }

        return( throttled ? 1 : 0 );

}


/* 
*  Digi Read OOB Callback
*
*  Digi Read OOB Callback handles reads on the out of band port.
*  When called we know port and port->private are not NULL and
*  the port->serial is valid.  It returns 0 if successful, and
*  -1 if the sanity checks failed.
*/

static int digi_read_oob_callback( struct urb *urb )
{

        struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
        struct usb_serial *serial = port->serial;
        struct digi_port *priv = usb_get_serial_port_data(port);
        int opcode, line, status, val;
        int i;


dbg( "digi_read_oob_callback: port=%d, len=%d", priv->dp_port_num,
urb->actual_length );

        /* handle each oob command */
        for( i=0; i<urb->actual_length-3; ) {

                opcode = ((unsigned char *)urb->transfer_buffer)[i++];
                line = ((unsigned char *)urb->transfer_buffer)[i++];
                status = ((unsigned char *)urb->transfer_buffer)[i++];
                val = ((unsigned char *)urb->transfer_buffer)[i++];

dbg( "digi_read_oob_callback: opcode=%d, line=%d, status=%d, val=%d",
opcode, line, status, val );

                if( status != 0 || line >= serial->type->num_ports )
                        continue;

                port = serial->port[line];

                if ((priv=usb_get_serial_port_data(port)) == NULL )
                        return -1;

                if( opcode == DIGI_CMD_READ_INPUT_SIGNALS ) {

                        spin_lock( &priv->dp_port_lock );

                        /* convert from digi flags to termiox flags */
                        if( val & DIGI_READ_INPUT_SIGNALS_CTS ) {
                                priv->dp_modem_signals |= TIOCM_CTS;
                                /* port must be open to use tty struct */
                                if( port->open_count
                                && port->tty->termios->c_cflag & CRTSCTS ) {
                                        port->tty->hw_stopped = 0;
                                        digi_wakeup_write( port );
                                }
                        } else {
                                priv->dp_modem_signals &= ~TIOCM_CTS;
                                /* port must be open to use tty struct */
                                if( port->open_count
                                && port->tty->termios->c_cflag & CRTSCTS ) {
                                        port->tty->hw_stopped = 1;
                                }
                        }
                        if( val & DIGI_READ_INPUT_SIGNALS_DSR )
                                priv->dp_modem_signals |= TIOCM_DSR;
                        else
                                priv->dp_modem_signals &= ~TIOCM_DSR;
                        if( val & DIGI_READ_INPUT_SIGNALS_RI )
                                priv->dp_modem_signals |= TIOCM_RI;
                        else
                                priv->dp_modem_signals &= ~TIOCM_RI;
                        if( val & DIGI_READ_INPUT_SIGNALS_DCD )
                                priv->dp_modem_signals |= TIOCM_CD;
                        else
                                priv->dp_modem_signals &= ~TIOCM_CD;

                        wake_up_interruptible( &priv->dp_modem_change_wait );
                        spin_unlock( &priv->dp_port_lock );

                } else if( opcode == DIGI_CMD_TRANSMIT_IDLE ) {

                        spin_lock( &priv->dp_port_lock );
                        priv->dp_transmit_idle = 1;
                        wake_up_interruptible( &priv->dp_transmit_idle_wait );
                        spin_unlock( &priv->dp_port_lock );

                } else if( opcode == DIGI_CMD_IFLUSH_FIFO ) {

                        wake_up( &priv->dp_flush_wait );

                }

        }

        return( 0 );

}


static int __init digi_init (void)
{
        int retval;
        retval = usb_serial_register(&digi_acceleport_2_device);
        if (retval)
                goto failed_acceleport_2_device;
        retval = usb_serial_register(&digi_acceleport_4_device);
        if (retval) 
                goto failed_acceleport_4_device;
        retval = usb_register(&digi_driver);
        if (retval)
                goto failed_usb_register;
        info(DRIVER_VERSION ":" DRIVER_DESC);
        return 0;
failed_usb_register:
        usb_serial_deregister(&digi_acceleport_4_device);
failed_acceleport_4_device:
        usb_serial_deregister(&digi_acceleport_2_device);
failed_acceleport_2_device:
        return retval;
}


static void __exit digi_exit (void)
{
        usb_deregister (&digi_driver);
        usb_serial_deregister (&digi_acceleport_2_device);
        usb_serial_deregister (&digi_acceleport_4_device);
}


module_init(digi_init);
module_exit(digi_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");