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ftdi_sio.c

/*
 * USB FTDI SIO driver
 *
 *    Copyright (C) 1999 - 2001
 *        Greg Kroah-Hartman (greg@kroah.com)
 *          Bill Ryder (bryder@sgi.com)
 *    Copyright (C) 2002
 *        Kuba Ober (kuba@mareimbrium.org)
 *
 *    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.
 *
 * See Documentation/usb/usb-serial.txt for more information on using this driver
 *
 * See http://ftdi-usb-sio.sourceforge.net for upto date testing info
 *    and extra documentation
 *
 * (21/Jul/2004) Ian Abbott
 *      Incorporated Steven Turner's code to add support for the FT2232C chip.
 *      The prelimilary port to the 2.6 kernel was by Rus V. Brushkoff.  I have
 *      fixed a couple of things.
 *
 * (27/May/2004) Ian Abbott
 *      Improved throttling code, mostly stolen from the WhiteHEAT driver.
 *
 * (26/Mar/2004) Jan Capek
 *      Added PID's for ICD-U20/ICD-U40 - incircuit PIC debuggers from CCS Inc.
 *
 * (09/Feb/2004) Ian Abbott
 *      Changed full name of USB-UIRT device to avoid "/" character.
 *      Added FTDI's alternate PID (0x6006) for FT232/245 devices.
 *      Added PID for "ELV USB Module UO100" from Stefan Frings.
 * 
 * (21/Oct/2003) Ian Abbott
 *      Renamed some VID/PID macros for Matrix Orbital and Perle Systems
 *      devices.  Removed Matrix Orbital and Perle Systems devices from the
 *      8U232AM device table, but left them in the FT232BM table, as they are
 *      known to use only FT232BM.
 *
 * (17/Oct/2003) Scott Allen
 *      Added vid/pid for Perle Systems UltraPort USB serial converters
 *
 * (21/Sep/2003) Ian Abbott
 *      Added VID/PID for Omnidirectional Control Technology US101 USB to
 *      RS-232 adapter (also rebadged as Dick Smith Electronics XH6381).
 *      VID/PID supplied by Donald Gordon.
 *
 * (19/Aug/2003) Ian Abbott
 *      Freed urb's transfer buffer in write bulk callback.
 *      Omitted some paranoid checks in write bulk callback that don't matter.
 *      Scheduled work in write bulk callback regardless of port's open count.
 *
 * (05/Aug/2003) Ian Abbott
 *      Added VID/PID for ID TECH IDT1221U USB to RS-232 adapter.
 *      VID/PID provided by Steve Briggs.
 *
 * (23/Jul/2003) Ian Abbott
 *      Added PIDs for CrystalFontz 547, 633, 631, 635, 640 and 640 from
 *      Wayne Wylupski.
 *
 * (10/Jul/2003) David Glance
 *      Added PID for DSS-20 SyncStation cradle for Sony-Ericsson P800.
 *
 * (27/Jun/2003) Ian Abbott
 *    Reworked the urb handling logic.  We have no more pool, but dynamically
 *    allocate the urb and the transfer buffer on the fly.  In testing this
 *    does not incure any measurable overhead.  This also relies on the fact
 *    that we have proper reference counting logic for urbs.  I nicked this
 *    from Greg KH's Visor driver.
 *      
 * (23/Jun/2003) Ian Abbott
 *      Reduced flip buffer pushes and corrected a data length test in
 *      ftdi_read_bulk_callback.
 *      Defererence pointers after any paranoid checks, not before.
 *
 * (21/Jun/2003) Erik Nygren
 *      Added support for Home Electronics Tira-1 IR transceiver using FT232BM chip.
 *      See <http://www.home-electro.com/tira1.htm>.  Only operates properly 
 *      at 100000 and RTS-CTS, so set custom divisor mode on startup.
 *      Also force the Tira-1 and USB-UIRT to only use their custom baud rates.
 *
 * (18/Jun/2003) Ian Abbott
 *      Added Device ID of the USB relais from Rudolf Gugler (backported from
 *      Philipp Gühring's patch for 2.5.x kernel).
 *      Moved read transfer buffer reallocation into startup function.
 *      Free existing write urb and transfer buffer in startup function.
 *      Only use urbs in write urb pool that were successfully allocated.
 *      Moved some constant macros out of functions.
 *      Minor whitespace and comment changes.
 *
 * (12/Jun/2003) David Norwood
 *      Added support for USB-UIRT IR transceiver using 8U232AM chip.
 *      See <http://home.earthlink.net/~jrhees/USBUIRT/index.htm>.  Only
 *      operates properly at 312500, so set custom divisor mode on startup.
 *
 * (12/Jun/2003) Ian Abbott
 *      Added Sealevel SeaLINK+ 210x, 220x, 240x, 280x vid/pids from Tuan Hoang
 *      - I've eliminated some that don't seem to exist!
 *      Added Home Electronics Tira-1 IR transceiver pid from Chris Horn
 *      Some whitespace/coding-style cleanups
 *
 * (11/Jun/2003) Ian Abbott
 *      Fixed unsafe spinlock usage in ftdi_write
 *
 * (24/Feb/2003) Richard Shooter
 *      Increase read buffer size to improve read speeds at higher baud rates
 *      (specifically tested with up to 1Mb/sec at 1.5M baud)
 *
 * (23/Feb/2003) John Wilkins
 *      Added Xon/xoff flow control (activating support in the ftdi device)
 *      Added vid/pid for Videonetworks/Homechoice (UK ISP)
 *
 * (23/Feb/2003) Bill Ryder
 *      Added matrix orb device vid/pids from Wayne Wylupski
 *
 * (19/Feb/2003) Ian Abbott
 *      For TIOCSSERIAL, set alt_speed to 0 when ASYNC_SPD_MASK value has
 *      changed to something other than ASYNC_SPD_HI, ASYNC_SPD_VHI,
 *      ASYNC_SPD_SHI or ASYNC_SPD_WARP.  Also, unless ASYNC_SPD_CUST is in
 *      force, don't bother changing baud rate when custom_divisor has changed.
 *
 * (18/Feb/2003) Ian Abbott
 *      Fixed TIOCMGET handling to include state of DTR and RTS, the state
 *      of which are now saved by set_dtr() and set_rts().
 *      Fixed improper storage class for buf in set_dtr() and set_rts().
 *      Added FT232BM chip type and support for its extra baud rates (compared
 *      to FT8U232AM).
 *      Took account of special case divisor values for highest baud rates of
 *      FT8U232AM and FT232BM.
 *      For TIOCSSERIAL, forced alt_speed to 0 when ASYNC_SPD_CUST kludge used,
 *      as previous alt_speed setting is now stale.
 *      Moved startup code common between the startup routines for the
 *      different chip types into a common subroutine.
 *
 * (17/Feb/2003) Bill Ryder
 *      Added write urb buffer pool on a per device basis
 *      Added more checking for open file on callbacks (fixed OOPS)
 *      Added CrystalFontz 632 and 634 PIDs 
 *         (thanx to CrystalFontz for the sample devices - they flushed out
 *           some driver bugs)
 *      Minor debugging message changes
 *      Added throttle, unthrottle and chars_in_buffer functions
 *      Fixed FTDI_SIO (the original device) bug
 *      Fixed some shutdown handling
 *      
 * 
 * 
 * 
 * (07/Jun/2002) Kuba Ober
 *    Changed FTDI_SIO_BASE_BAUD_TO_DIVISOR macro into ftdi_baud_to_divisor
 *    function. It was getting too complex.
 *    Fix the divisor calculation logic which was setting divisor of 0.125
 *    instead of 0.5 for fractional parts of divisor equal to 5/8, 6/8, 7/8.
 *    Also make it bump up the divisor to next integer in case of 7/8 - it's
 *    a better approximation.
 *
 * (25/Jul/2002) Bill Ryder inserted Dmitri's TIOCMIWAIT patch
 *      Not tested by me but it doesn't break anything I use.
 * 
 * (04/Jan/2002) Kuba Ober
 *    Implemented 38400 baudrate kludge, where it can be substituted with other
 *      values. That's the only way to set custom baudrates.
 *    Implemented TIOCSSERIAL, TIOCGSERIAL ioctl's so that setserial is happy.
 *    FIXME: both baudrate things should eventually go to usbserial.c as other
 *      devices may need that functionality too. Actually, it can probably be
 *      merged in serial.c somehow - too many drivers repeat this code over
 *      and over.
 *    Fixed baudrate forgetfulness - open() used to reset baudrate to 9600 every time.
 *    Divisors for baudrates are calculated by a macro.
 *    Small code cleanups. Ugly whitespace changes for Plato's sake only ;-].
 *
 * (04/Nov/2001) Bill Ryder
 *    Fixed bug in read_bulk_callback where incorrect urb buffer was used.
 *    Cleaned up write offset calculation
 *    Added write_room since default values can be incorrect for sio
 *    Changed write_bulk_callback to use same queue_task as other drivers
 *        (the previous version caused panics)
 *    Removed port iteration code since the device only has one I/O port and it
 *      was wrong anyway.
 * 
 * (31/May/2001) gkh
 *    Switched from using spinlock to a semaphore, which fixes lots of problems.
 *
 * (23/May/2001)   Bill Ryder
 *    Added runtime debug patch (thanx Tyson D Sawyer).
 *    Cleaned up comments for 8U232
 *    Added parity, framing and overrun error handling
 *    Added receive break handling.
 * 
 * (04/08/2001) gb
 *    Identify version on module load.
 *       
 * (18/March/2001) Bill Ryder
 *    (Not released)
 *    Added send break handling. (requires kernel patch too)
 *    Fixed 8U232AM hardware RTS/CTS etc status reporting.
 *    Added flipbuf fix copied from generic device
 * 
 * (12/3/2000) Bill Ryder
 *    Added support for 8U232AM device.
 *    Moved PID and VIDs into header file only.
 *    Turned on low-latency for the tty (device will do high baudrates)
 *    Added shutdown routine to close files when device removed.
 *    More debug and error message cleanups.
 *
 * (11/13/2000) Bill Ryder
 *    Added spinlock protected open code and close code.
 *    Multiple opens work (sort of - see webpage mentioned above).
 *    Cleaned up comments. Removed multiple PID/VID definitions.
 *    Factorised cts/dtr code
 *    Made use of __FUNCTION__ in dbg's
 *      
 * (11/01/2000) Adam J. Richter
 *    usb_device_id table support
 * 
 * (10/05/2000) gkh
 *    Fixed bug with urb->dev not being set properly, now that the usb
 *    core needs it.
 * 
 * (09/11/2000) gkh
 *    Removed DEBUG #ifdefs with call to usb_serial_debug_data
 *
 * (07/19/2000) gkh
 *    Added module_init and module_exit functions to handle the fact that this
 *    driver is a loadable module now.
 *
 * (04/04/2000) Bill Ryder 
 *    Fixed bugs in TCGET/TCSET ioctls (by removing them - they are
 *        handled elsewhere in the tty io driver chain).
 *
 * (03/30/2000) Bill Ryder 
 *    Implemented lots of ioctls
 *    Fixed a race condition in write
 *    Changed some dbg's to errs
 *
 * (03/26/2000) gkh
 *    Split driver up into device specific pieces.
 *
 */

/* Bill Ryder - bryder@sgi.com - wrote the FTDI_SIO implementation */
/* Thanx to FTDI for so kindly providing details of the protocol required */
/*   to talk to the device */
/* Thanx to gkh and the rest of the usb dev group for all code I have assimilated :-) */

#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 <asm/uaccess.h>
#include <linux/usb.h>
#include <linux/serial.h>
#include <linux/usb/serial.h>
#include "ftdi_sio.h"

/*
 * Version Information
 */
#define DRIVER_VERSION "v1.4.3"
#define DRIVER_AUTHOR "Greg Kroah-Hartman <greg@kroah.com>, Bill Ryder <bryder@sgi.com>, Kuba Ober <kuba@mareimbrium.org>"
#define DRIVER_DESC "USB FTDI Serial Converters Driver"

static int debug;
static __u16 vendor = FTDI_VID;
static __u16 product;

/* struct ftdi_sio_quirk is used by devices requiring special attention. */
struct ftdi_sio_quirk {
      void (*setup)(struct usb_serial *); /* Special settings during startup. */
};

static void  ftdi_USB_UIRT_setup    (struct usb_serial *serial);
static void  ftdi_HE_TIRA1_setup    (struct usb_serial *serial);

static struct ftdi_sio_quirk ftdi_USB_UIRT_quirk = {
      .setup = ftdi_USB_UIRT_setup,
};

static struct ftdi_sio_quirk ftdi_HE_TIRA1_quirk = {
      .setup = ftdi_HE_TIRA1_setup,
};

/*
 * The 8U232AM has the same API as the sio except for:
 * - it can support MUCH higher baudrates; up to:
 *   o 921600 for RS232 and 2000000 for RS422/485 at 48MHz
 *   o 230400 at 12MHz
 *   so .. 8U232AM's baudrate setting codes are different
 * - it has a two byte status code.
 * - it returns characters every 16ms (the FTDI does it every 40ms)
 *
 * the bcdDevice value is used to differentiate FT232BM and FT245BM from
 * the earlier FT8U232AM and FT8U232BM.  For now, include all known VID/PID
 * combinations in both tables.
 * FIXME: perhaps bcdDevice can also identify 12MHz FT8U232AM devices,
 * but I don't know if those ever went into mass production. [Ian Abbott]
 */



static struct usb_device_id id_table_combined [] = {
      { USB_DEVICE(FTDI_VID, FTDI_AMC232_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_CANUSB_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ACTZWAVE_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_IRTRANS_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_IPLUS_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_SIO_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_8U232AM_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_8U232AM_ALT_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_8U2232C_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MICRO_CHAMELEON_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_RELAIS_PID) },
      { USB_DEVICE(INTERBIOMETRICS_VID, INTERBIOMETRICS_IOBOARD_PID) },
      { USB_DEVICE(INTERBIOMETRICS_VID, INTERBIOMETRICS_MINI_IOBOARD_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_XF_632_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_XF_634_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_XF_547_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_XF_633_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_XF_631_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_XF_635_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_XF_640_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_XF_642_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_DSS20_PID) },
      { USB_DEVICE(FTDI_NF_RIC_VID, FTDI_NF_RIC_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_VNHCPCUSB_D_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MTXORB_0_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MTXORB_1_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MTXORB_2_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MTXORB_3_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MTXORB_4_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MTXORB_5_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MTXORB_6_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_PERLE_ULTRAPORT_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_PIEGROUP_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_TNC_X_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2101_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2102_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2103_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2104_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2201_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2201_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2202_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2202_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2203_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2203_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2401_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2401_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2401_3_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2401_4_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2402_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2402_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2402_3_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2402_4_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2403_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2403_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2403_3_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2403_4_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2801_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2801_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2801_3_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2801_4_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2801_5_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2801_6_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2801_7_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2801_8_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2802_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2802_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2802_3_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2802_4_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2802_5_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2802_6_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2802_7_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2802_8_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2803_1_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2803_2_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2803_3_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2803_4_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2803_5_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2803_6_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2803_7_PID) },
      { USB_DEVICE(SEALEVEL_VID, SEALEVEL_2803_8_PID) },
      { USB_DEVICE(IDTECH_VID, IDTECH_IDT1221U_PID) },
      { USB_DEVICE(OCT_VID, OCT_US101_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_HE_TIRA1_PID),
            .driver_info = (kernel_ulong_t)&ftdi_HE_TIRA1_quirk },
      { USB_DEVICE(FTDI_VID, FTDI_USB_UIRT_PID),
            .driver_info = (kernel_ulong_t)&ftdi_USB_UIRT_quirk },
      { USB_DEVICE(FTDI_VID, PROTEGO_SPECIAL_1) },
      { USB_DEVICE(FTDI_VID, PROTEGO_R2X0) },
      { USB_DEVICE(FTDI_VID, PROTEGO_SPECIAL_3) },
      { USB_DEVICE(FTDI_VID, PROTEGO_SPECIAL_4) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E808_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E809_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E80A_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E80B_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E80C_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E80D_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E80E_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E80F_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E888_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E889_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E88A_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E88B_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E88C_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E88D_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E88E_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GUDEADS_E88F_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ELV_UO100_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ELV_UM100_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ELV_UR100_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ELV_ALC8500_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_PYRAMID_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ELV_FHZ1000PC_PID) },
      /*
       * These will probably use user-space drivers.  Uncomment them if
       * you need them or use the user-specified vendor/product module
       * parameters (see ftdi_sio.h for the numbers).  Make a fuss if
       * you think the driver should recognize any of them by default.
       */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_CLI7000_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_PPS7330_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_TFM100_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_UDF77_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_UIO88_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_UAD8_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_UDA7_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_USI2_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_T1100_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_PCD200_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_ULA200_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_CSI8_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_EM1000DL_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_PCK100_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_RFP500_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_FS20SIG_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_WS300PC_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_FHZ1300PC_PID) }, */
      /* { USB_DEVICE(FTDI_VID, FTDI_ELV_WS500_PID) }, */
      { USB_DEVICE(FTDI_VID, LINX_SDMUSBQSS_PID) },
      { USB_DEVICE(FTDI_VID, LINX_MASTERDEVEL2_PID) },
      { USB_DEVICE(FTDI_VID, LINX_FUTURE_0_PID) },
      { USB_DEVICE(FTDI_VID, LINX_FUTURE_1_PID) },
      { USB_DEVICE(FTDI_VID, LINX_FUTURE_2_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_CCSICDU20_0_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_CCSICDU40_1_PID) },
      { USB_DEVICE(FTDI_VID, INSIDE_ACCESSO) },
      { USB_DEVICE(INTREPID_VID, INTREPID_VALUECAN_PID) },
      { USB_DEVICE(INTREPID_VID, INTREPID_NEOVI_PID) },
      { USB_DEVICE(FALCOM_VID, FALCOM_TWIST_PID) },
      { USB_DEVICE(FALCOM_VID, FALCOM_SAMBA_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_SUUNTO_SPORTS_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_RM_CANVIEW_PID) },
      { USB_DEVICE(BANDB_VID, BANDB_USOTL4_PID) },
      { USB_DEVICE(BANDB_VID, BANDB_USTL4_PID) },
      { USB_DEVICE(BANDB_VID, BANDB_USO9ML2_PID) },
      { USB_DEVICE(FTDI_VID, EVER_ECO_PRO_CDS) },
      { USB_DEVICE(FTDI_VID, FTDI_4N_GALAXY_DE_0_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_4N_GALAXY_DE_1_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_4N_GALAXY_DE_2_PID) },
      { USB_DEVICE(FTDI_VID, XSENS_CONVERTER_0_PID) },
      { USB_DEVICE(FTDI_VID, XSENS_CONVERTER_1_PID) },
      { USB_DEVICE(FTDI_VID, XSENS_CONVERTER_2_PID) },
      { USB_DEVICE(FTDI_VID, XSENS_CONVERTER_3_PID) },
      { USB_DEVICE(FTDI_VID, XSENS_CONVERTER_4_PID) },
      { USB_DEVICE(FTDI_VID, XSENS_CONVERTER_5_PID) },
      { USB_DEVICE(FTDI_VID, XSENS_CONVERTER_6_PID) },
      { USB_DEVICE(FTDI_VID, XSENS_CONVERTER_7_PID) },
      { USB_DEVICE(MOBILITY_VID, MOBILITY_USB_SERIAL_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ACTIVE_ROBOTS_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MHAM_KW_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MHAM_YS_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MHAM_Y6_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MHAM_Y8_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MHAM_IC_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MHAM_DB9_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MHAM_RS232_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_MHAM_Y9_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_TERATRONIK_VCP_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_TERATRONIK_D2XX_PID) },
      { USB_DEVICE(EVOLUTION_VID, EVOLUTION_ER1_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ARTEMIS_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ATIK_ATK16_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ATIK_ATK16C_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ATIK_ATK16HR_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ATIK_ATK16HRC_PID) },
      { USB_DEVICE(KOBIL_VID, KOBIL_CONV_B1_PID) },
      { USB_DEVICE(KOBIL_VID, KOBIL_CONV_KAAN_PID) },
      { USB_DEVICE(POSIFLEX_VID, POSIFLEX_PP7000_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_TTUSB_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ECLO_COM_1WIRE_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_WESTREX_MODEL_777_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_WESTREX_MODEL_8900F_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_PCDJ_DAC2_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_RRCIRKITS_LOCOBUFFER_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ASK_RDR400_PID) },
      { USB_DEVICE(ICOM_ID1_VID, ICOM_ID1_PID) },
      { USB_DEVICE(PAPOUCH_VID, PAPOUCH_TMU_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_ACG_HFDUAL_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_YEI_SERVOCENTER31_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_THORLABS_PID) },
      { USB_DEVICE(TESTO_VID, TESTO_USB_INTERFACE_PID) },
      { USB_DEVICE(FTDI_VID, FTDI_GAMMA_SCOUT_PID) },
      { },                          /* Optional parameter entry */
      { }                           /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, id_table_combined);

static struct usb_driver ftdi_driver = {
      .name =           "ftdi_sio",
      .probe =    usb_serial_probe,
      .disconnect =     usb_serial_disconnect,
      .id_table = id_table_combined,
      .no_dynamic_id =  1,
};

static const char *ftdi_chip_name[] = {
      [SIO] = "SIO",    /* the serial part of FT8U100AX */
      [FT8U232AM] = "FT8U232AM",
      [FT232BM] = "FT232BM",
      [FT2232C] = "FT2232C",
};


/* Constants for read urb and write urb */
#define BUFSZ 512
#define PKTSZ 64

/* rx_flags */
#define THROTTLED       0x01
#define ACTUALLY_THROTTLED    0x02

struct ftdi_private {
      ftdi_chip_type_t chip_type;
                        /* type of the device, either SIO or FT8U232AM */
      int baud_base;          /* baud base clock for divisor setting */
      int custom_divisor;     /* custom_divisor kludge, this is for baud_base (different from what goes to the chip!) */
      __u16 last_set_data_urb_value ;
                        /* the last data state set - needed for doing a break */
        int write_offset;       /* This is the offset in the usb data block to write the serial data - 
                         * it is different between devices
                         */
      int flags;        /* some ASYNC_xxxx flags are supported */
      unsigned long last_dtr_rts;   /* saved modem control outputs */
        wait_queue_head_t delta_msr_wait; /* Used for TIOCMIWAIT */
      char prev_status, diff_status;        /* Used for TIOCMIWAIT */
      __u8 rx_flags;          /* receive state flags (throttling) */
      spinlock_t rx_lock;     /* spinlock for receive state */
      struct work_struct rx_work;
      int rx_processed;
      unsigned long rx_bytes;

      __u16 interface;  /* FT2232C port interface (0 for FT232/245) */

      int force_baud;         /* if non-zero, force the baud rate to this value */
      int force_rtscts; /* if non-zero, force RTS-CTS to always be enabled */

      spinlock_t tx_lock;     /* spinlock for transmit state */
      unsigned long tx_bytes;
      unsigned long tx_outstanding_bytes;
      unsigned long tx_outstanding_urbs;
};

/* Used for TIOCMIWAIT */
#define FTDI_STATUS_B0_MASK   (FTDI_RS0_CTS | FTDI_RS0_DSR | FTDI_RS0_RI | FTDI_RS0_RLSD)
#define FTDI_STATUS_B1_MASK   (FTDI_RS_BI)
/* End TIOCMIWAIT */

#define FTDI_IMPL_ASYNC_FLAGS = ( ASYNC_SPD_HI | ASYNC_SPD_VHI \
 ASYNC_SPD_CUST | ASYNC_SPD_SHI | ASYNC_SPD_WARP )

/* function prototypes for a FTDI serial converter */
static int  ftdi_sio_probe    (struct usb_serial *serial, const struct usb_device_id *id);
static int  ftdi_sio_attach         (struct usb_serial *serial);
static void ftdi_shutdown           (struct usb_serial *serial);
static int  ftdi_open               (struct usb_serial_port *port, struct file *filp);
static void ftdi_close              (struct usb_serial_port *port, struct file *filp);
static int  ftdi_write              (struct usb_serial_port *port, const unsigned char *buf, int count);
static int  ftdi_write_room         (struct usb_serial_port *port);
static int  ftdi_chars_in_buffer    (struct usb_serial_port *port);
static void ftdi_write_bulk_callback      (struct urb *urb, struct pt_regs *regs);
static void ftdi_read_bulk_callback (struct urb *urb, struct pt_regs *regs);
static void ftdi_process_read       (void *param);
static void ftdi_set_termios        (struct usb_serial_port *port, struct termios * old);
static int  ftdi_tiocmget               (struct usb_serial_port *port, struct file *file);
static int  ftdi_tiocmset           (struct usb_serial_port *port, struct file * file, unsigned int set, unsigned int clear);
static int  ftdi_ioctl              (struct usb_serial_port *port, struct file * file, unsigned int cmd, unsigned long arg);
static void ftdi_break_ctl          (struct usb_serial_port *port, int break_state );
static void ftdi_throttle           (struct usb_serial_port *port);
static void ftdi_unthrottle         (struct usb_serial_port *port);

static unsigned short int ftdi_232am_baud_base_to_divisor (int baud, int base);
static unsigned short int ftdi_232am_baud_to_divisor (int baud);
static __u32 ftdi_232bm_baud_base_to_divisor (int baud, int base);
static __u32 ftdi_232bm_baud_to_divisor (int baud);

static struct usb_serial_driver ftdi_sio_device = {
      .driver = {
            .owner =    THIS_MODULE,
            .name =           "ftdi_sio",
      },
      .description =          "FTDI USB Serial Device",
      .id_table =       id_table_combined,
      .num_interrupt_in =     0,
      .num_bulk_in =          1,
      .num_bulk_out =         1,
      .num_ports =            1,
      .probe =          ftdi_sio_probe,
      .open =                 ftdi_open,
      .close =          ftdi_close,
      .throttle =       ftdi_throttle,
      .unthrottle =           ftdi_unthrottle,
      .write =          ftdi_write,
      .write_room =           ftdi_write_room,
      .chars_in_buffer =      ftdi_chars_in_buffer,
      .read_bulk_callback =   ftdi_read_bulk_callback,
      .write_bulk_callback =  ftdi_write_bulk_callback,
      .tiocmget =             ftdi_tiocmget,
      .tiocmset =             ftdi_tiocmset,
      .ioctl =          ftdi_ioctl,
      .set_termios =          ftdi_set_termios,
      .break_ctl =            ftdi_break_ctl,
      .attach =         ftdi_sio_attach,
      .shutdown =       ftdi_shutdown,
};


#define WDR_TIMEOUT 5000 /* default urb timeout */
#define WDR_SHORT_TIMEOUT 1000      /* shorter urb timeout */

/* High and low are for DTR, RTS etc etc */
#define HIGH 1
#define LOW 0

/* number of outstanding urbs to prevent userspace DoS from happening */
#define URB_UPPER_LIMIT 42

/*
 * ***************************************************************************
 * Utlity functions
 * ***************************************************************************
 */

static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
{
      unsigned short int divisor;
      int divisor3 = base / 2 / baud; // divisor shifted 3 bits to the left
      if ((divisor3 & 0x7) == 7) divisor3 ++; // round x.7/8 up to x+1
      divisor = divisor3 >> 3;
      divisor3 &= 0x7;
      if (divisor3 == 1) divisor |= 0xc000; else // 0.125
      if (divisor3 >= 4) divisor |= 0x4000; else // 0.5
      if (divisor3 != 0) divisor |= 0x8000;      // 0.25
      if (divisor == 1) divisor = 0;      /* special case for maximum baud rate */
      return divisor;
}

static unsigned short int ftdi_232am_baud_to_divisor(int baud)
{
       return(ftdi_232am_baud_base_to_divisor(baud, 48000000));
}

static __u32 ftdi_232bm_baud_base_to_divisor(int baud, int base)
{
      static const unsigned char divfrac[8] = { 0, 3, 2, 4, 1, 5, 6, 7 };
      __u32 divisor;
      int divisor3 = base / 2 / baud; // divisor shifted 3 bits to the left
      divisor = divisor3 >> 3;
      divisor |= (__u32)divfrac[divisor3 & 0x7] << 14;
      /* Deal with special cases for highest baud rates. */
      if (divisor == 1) divisor = 0; else // 1.0
      if (divisor == 0x4001) divisor = 1; // 1.5
      return divisor;
}

static __u32 ftdi_232bm_baud_to_divisor(int baud)
{
       return(ftdi_232bm_baud_base_to_divisor(baud, 48000000));
}

#define set_mctrl(port, set)        update_mctrl((port), (set), 0)
#define clear_mctrl(port, clear)    update_mctrl((port), 0, (clear))

static int update_mctrl(struct usb_serial_port *port, unsigned int set, unsigned int clear)
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      char *buf;
      unsigned urb_value;
      int rv;

      if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0) {
            dbg("%s - DTR|RTS not being set|cleared", __FUNCTION__);
            return 0;   /* no change */
      }

      buf = kmalloc(1, GFP_NOIO);
      if (!buf) {
            return -ENOMEM;
      }

      clear &= ~set;    /* 'set' takes precedence over 'clear' */
      urb_value = 0;
      if (clear & TIOCM_DTR)
            urb_value |= FTDI_SIO_SET_DTR_LOW;
      if (clear & TIOCM_RTS)
            urb_value |= FTDI_SIO_SET_RTS_LOW;
      if (set & TIOCM_DTR)
            urb_value |= FTDI_SIO_SET_DTR_HIGH;
      if (set & TIOCM_RTS)
            urb_value |= FTDI_SIO_SET_RTS_HIGH;
      rv = usb_control_msg(port->serial->dev,
                         usb_sndctrlpipe(port->serial->dev, 0),
                         FTDI_SIO_SET_MODEM_CTRL_REQUEST, 
                         FTDI_SIO_SET_MODEM_CTRL_REQUEST_TYPE,
                         urb_value, priv->interface,
                         buf, 0, WDR_TIMEOUT);

      kfree(buf);
      if (rv < 0) {
            err("%s Error from MODEM_CTRL urb: DTR %s, RTS %s",
                        __FUNCTION__,
                        (set & TIOCM_DTR) ? "HIGH" :
                        (clear & TIOCM_DTR) ? "LOW" : "unchanged",
                        (set & TIOCM_RTS) ? "HIGH" :
                        (clear & TIOCM_RTS) ? "LOW" : "unchanged");
      } else {
            dbg("%s - DTR %s, RTS %s", __FUNCTION__,
                        (set & TIOCM_DTR) ? "HIGH" :
                        (clear & TIOCM_DTR) ? "LOW" : "unchanged",
                        (set & TIOCM_RTS) ? "HIGH" :
                        (clear & TIOCM_RTS) ? "LOW" : "unchanged");
            priv->last_dtr_rts = (priv->last_dtr_rts & ~clear) | set;
      }
      return rv;
}


static __u32 get_ftdi_divisor(struct usb_serial_port * port);


static int change_speed(struct usb_serial_port *port)
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      char *buf;
        __u16 urb_value;
      __u16 urb_index;
      __u32 urb_index_value;
      int rv;

      buf = kmalloc(1, GFP_NOIO);
      if (!buf)
            return -ENOMEM;

      urb_index_value = get_ftdi_divisor(port);
      urb_value = (__u16)urb_index_value;
      urb_index = (__u16)(urb_index_value >> 16);
      if (priv->interface) {  /* FT2232C */
            urb_index = (__u16)((urb_index << 8) | priv->interface);
      }
      
      rv = usb_control_msg(port->serial->dev,
                      usb_sndctrlpipe(port->serial->dev, 0),
                      FTDI_SIO_SET_BAUDRATE_REQUEST,
                      FTDI_SIO_SET_BAUDRATE_REQUEST_TYPE,
                      urb_value, urb_index,
                      buf, 0, WDR_SHORT_TIMEOUT);

      kfree(buf);
      return rv;
}


static __u32 get_ftdi_divisor(struct usb_serial_port * port)
{ /* get_ftdi_divisor */
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      __u32 div_value = 0;
      int div_okay = 1;
      int baud;

      /*
       * The logic involved in setting the baudrate can be cleanly split in 3 steps.
       * Obtaining the actual baud rate is a little tricky since unix traditionally
       * somehow ignored the possibility to set non-standard baud rates.
       * 1. Standard baud rates are set in tty->termios->c_cflag
       * 2. If these are not enough, you can set any speed using alt_speed as follows:
       *    - set tty->termios->c_cflag speed to B38400
       *    - set your real speed in tty->alt_speed; it gets ignored when
       *      alt_speed==0, (or)
       *    - call TIOCSSERIAL ioctl with (struct serial_struct) set as follows:
       *      flags & ASYNC_SPD_MASK == ASYNC_SPD_[HI, VHI, SHI, WARP], this just
       *      sets alt_speed to (HI: 57600, VHI: 115200, SHI: 230400, WARP: 460800)
       * ** Steps 1, 2 are done courtesy of tty_get_baud_rate
       * 3. You can also set baud rate by setting custom divisor as follows
       *    - set tty->termios->c_cflag speed to B38400
       *    - call TIOCSSERIAL ioctl with (struct serial_struct) set as follows:
       *      o flags & ASYNC_SPD_MASK == ASYNC_SPD_CUST
       *      o custom_divisor set to baud_base / your_new_baudrate
       * ** Step 3 is done courtesy of code borrowed from serial.c - I should really
       *    spend some time and separate+move this common code to serial.c, it is
       *    replicated in nearly every serial driver you see.
       */

      /* 1. Get the baud rate from the tty settings, this observes alt_speed hack */

      baud = tty_get_baud_rate(port->tty);
      dbg("%s - tty_get_baud_rate reports speed %d", __FUNCTION__, baud);

      /* 2. Observe async-compatible custom_divisor hack, update baudrate if needed */

      if (baud == 38400 &&
          ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST) &&
           (priv->custom_divisor)) {
            baud = priv->baud_base / priv->custom_divisor;
            dbg("%s - custom divisor %d sets baud rate to %d", __FUNCTION__, priv->custom_divisor, baud);
      }

      /* 3. Convert baudrate to device-specific divisor */

      if (!baud) baud = 9600; 
      switch(priv->chip_type) {
      case SIO: /* SIO chip */
            switch(baud) {
            case 300: div_value = ftdi_sio_b300; break;
            case 600: div_value = ftdi_sio_b600; break;
            case 1200: div_value = ftdi_sio_b1200; break;
            case 2400: div_value = ftdi_sio_b2400; break;
            case 4800: div_value = ftdi_sio_b4800; break;
            case 9600: div_value = ftdi_sio_b9600; break;
            case 19200: div_value = ftdi_sio_b19200; break;
            case 38400: div_value = ftdi_sio_b38400; break;
            case 57600: div_value = ftdi_sio_b57600;  break;
            case 115200: div_value = ftdi_sio_b115200; break;
            } /* baud */
            if (div_value == 0) {
                  dbg("%s - Baudrate (%d) requested is not supported", __FUNCTION__,  baud);
                  div_value = ftdi_sio_b9600;
                  div_okay = 0;
            }
            break;
      case FT8U232AM: /* 8U232AM chip */
            if (baud <= 3000000) {
                  div_value = ftdi_232am_baud_to_divisor(baud);
            } else {
                      dbg("%s - Baud rate too high!", __FUNCTION__);
                  div_value = ftdi_232am_baud_to_divisor(9600);
                  div_okay = 0;
            }
            break;
      case FT232BM: /* FT232BM chip */
      case FT2232C: /* FT2232C chip */
            if (baud <= 3000000) {
                  div_value = ftdi_232bm_baud_to_divisor(baud);
            } else {
                      dbg("%s - Baud rate too high!", __FUNCTION__);
                  div_value = ftdi_232bm_baud_to_divisor(9600);
                  div_okay = 0;
            }
            break;
      } /* priv->chip_type */

      if (div_okay) {
            dbg("%s - Baud rate set to %d (divisor 0x%lX) on chip %s",
                  __FUNCTION__, baud, (unsigned long)div_value,
                  ftdi_chip_name[priv->chip_type]);
      }

      return(div_value);
}


static int get_serial_info(struct usb_serial_port * port, struct serial_struct __user * retinfo)
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      struct serial_struct tmp;

      if (!retinfo)
            return -EFAULT;
      memset(&tmp, 0, sizeof(tmp));
      tmp.flags = priv->flags;
      tmp.baud_base = priv->baud_base;
      tmp.custom_divisor = priv->custom_divisor;
      if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
            return -EFAULT;
      return 0;
} /* get_serial_info */


static int set_serial_info(struct usb_serial_port * port, struct serial_struct __user * newinfo)
{ /* set_serial_info */
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      struct serial_struct new_serial;
      struct ftdi_private old_priv;

      if (copy_from_user(&new_serial, newinfo, sizeof(new_serial)))
            return -EFAULT;
      old_priv = * priv;

      /* Do error checking and permission checking */

      if (!capable(CAP_SYS_ADMIN)) {
            if (((new_serial.flags & ~ASYNC_USR_MASK) !=
                 (priv->flags & ~ASYNC_USR_MASK)))
                  return -EPERM;
            priv->flags = ((priv->flags & ~ASYNC_USR_MASK) |
                         (new_serial.flags & ASYNC_USR_MASK));
            priv->custom_divisor = new_serial.custom_divisor;
            goto check_and_exit;
      }

      if ((new_serial.baud_base != priv->baud_base) &&
          (new_serial.baud_base < 9600))
            return -EINVAL;

      /* Make the changes - these are privileged changes! */

      priv->flags = ((priv->flags & ~ASYNC_FLAGS) |
                     (new_serial.flags & ASYNC_FLAGS));     
      priv->custom_divisor = new_serial.custom_divisor;

      port->tty->low_latency = (priv->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

check_and_exit:
      if ((old_priv.flags & ASYNC_SPD_MASK) !=
           (priv->flags & ASYNC_SPD_MASK)) {
            if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
                  port->tty->alt_speed = 57600;
            else if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
                  port->tty->alt_speed = 115200;
            else if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
                  port->tty->alt_speed = 230400;
            else if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
                  port->tty->alt_speed = 460800;
            else
                  port->tty->alt_speed = 0;
      }
      if (((old_priv.flags & ASYNC_SPD_MASK) !=
           (priv->flags & ASYNC_SPD_MASK)) ||
          (((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST) &&
           (old_priv.custom_divisor != priv->custom_divisor))) {
            change_speed(port);
      }
      
      return (0);

} /* set_serial_info */


/* Determine type of FTDI chip based on USB config and descriptor. */
static void ftdi_determine_type(struct usb_serial_port *port)
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      struct usb_serial *serial = port->serial;
      struct usb_device *udev = serial->dev;
      unsigned version;
      unsigned interfaces;

      /* Assume it is not the original SIO device for now. */
      priv->baud_base = 48000000 / 2;
      priv->write_offset = 0;

      version = le16_to_cpu(udev->descriptor.bcdDevice);
      interfaces = udev->actconfig->desc.bNumInterfaces;
      dbg("%s: bcdDevice = 0x%x, bNumInterfaces = %u", __FUNCTION__,
                  version, interfaces);
      if (interfaces > 1) {
            int inter;

            /* Multiple interfaces.  Assume FT2232C. */
            priv->chip_type = FT2232C;
            /* Determine interface code. */
            inter = serial->interface->altsetting->desc.bInterfaceNumber;
            if (inter == 0) {
                  priv->interface = PIT_SIOA;
            } else {
                  priv->interface = PIT_SIOB;
            }
            /* BM-type devices have a bug where bcdDevice gets set
             * to 0x200 when iSerialNumber is 0.  */
            if (version < 0x500) {
                  dbg("%s: something fishy - bcdDevice too low for multi-interface device",
                              __FUNCTION__);
            }
      } else if (version < 0x200) {
            /* Old device.  Assume its the original SIO. */
            priv->chip_type = SIO;
            priv->baud_base = 12000000 / 16;
            priv->write_offset = 1;
      } else if (version < 0x400) {
            /* Assume its an FT8U232AM (or FT8U245AM) */
            /* (It might be a BM because of the iSerialNumber bug,
             * but it will still work as an AM device.) */
            priv->chip_type = FT8U232AM;
      } else {
            /* Assume its an FT232BM (or FT245BM) */
            priv->chip_type = FT232BM;
      }
      info("Detected %s", ftdi_chip_name[priv->chip_type]);
}


/*
 * ***************************************************************************
 * Sysfs Attribute
 * ***************************************************************************
 */

static ssize_t show_latency_timer(struct device *dev, struct device_attribute *attr, char *buf)
{
      struct usb_serial_port *port = to_usb_serial_port(dev);
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      struct usb_device *udev;
      unsigned short latency = 0;
      int rv = 0;
      
      udev = to_usb_device(dev);
      
      dbg("%s",__FUNCTION__);
      
      rv = usb_control_msg(udev,
                       usb_rcvctrlpipe(udev, 0),
                       FTDI_SIO_GET_LATENCY_TIMER_REQUEST,
                       FTDI_SIO_GET_LATENCY_TIMER_REQUEST_TYPE,
                       0, priv->interface, 
                       (char*) &latency, 1, WDR_TIMEOUT);
      
      if (rv < 0) {
            dev_err(dev, "Unable to read latency timer: %i", rv);
            return -EIO;
      }
      return sprintf(buf, "%i\n", latency);
}

/* Write a new value of the latency timer, in units of milliseconds. */
static ssize_t store_latency_timer(struct device *dev, struct device_attribute *attr, const char *valbuf,
                           size_t count)
{
      struct usb_serial_port *port = to_usb_serial_port(dev);
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      struct usb_device *udev;
      char buf[1];
      int v = simple_strtoul(valbuf, NULL, 10);
      int rv = 0;
      
      udev = to_usb_device(dev);
      
      dbg("%s: setting latency timer = %i", __FUNCTION__, v);
      
      rv = usb_control_msg(udev,
                       usb_sndctrlpipe(udev, 0),
                       FTDI_SIO_SET_LATENCY_TIMER_REQUEST,
                       FTDI_SIO_SET_LATENCY_TIMER_REQUEST_TYPE,
                       v, priv->interface, 
                       buf, 0, WDR_TIMEOUT);
      
      if (rv < 0) {
            dev_err(dev, "Unable to write latency timer: %i", rv);
            return -EIO;
      }
      
      return count;
}

/* Write an event character directly to the FTDI register.  The ASCII
   value is in the low 8 bits, with the enable bit in the 9th bit. */
static ssize_t store_event_char(struct device *dev, struct device_attribute *attr, const char *valbuf,
                        size_t count)
{
      struct usb_serial_port *port = to_usb_serial_port(dev);
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      struct usb_device *udev;
      char buf[1];
      int v = simple_strtoul(valbuf, NULL, 10);
      int rv = 0;
      
      udev = to_usb_device(dev);
      
      dbg("%s: setting event char = %i", __FUNCTION__, v);
      
      rv = usb_control_msg(udev,
                       usb_sndctrlpipe(udev, 0),
                       FTDI_SIO_SET_EVENT_CHAR_REQUEST,
                       FTDI_SIO_SET_EVENT_CHAR_REQUEST_TYPE,
                       v, priv->interface, 
                       buf, 0, WDR_TIMEOUT);
      
      if (rv < 0) {
            dbg("Unable to write event character: %i", rv);
            return -EIO;
      }
      
      return count;
}

static DEVICE_ATTR(latency_timer, S_IWUSR | S_IRUGO, show_latency_timer, store_latency_timer);
static DEVICE_ATTR(event_char, S_IWUSR, NULL, store_event_char);

static void create_sysfs_attrs(struct usb_serial *serial)
{     
      struct ftdi_private *priv;
      struct usb_device *udev;

      dbg("%s",__FUNCTION__);
      
      priv = usb_get_serial_port_data(serial->port[0]);
      udev = serial->dev;
      
      /* XXX I've no idea if the original SIO supports the event_char
       * sysfs parameter, so I'm playing it safe.  */
      if (priv->chip_type != SIO) {
            dbg("sysfs attributes for %s", ftdi_chip_name[priv->chip_type]);
            device_create_file(&udev->dev, &dev_attr_event_char);
            if (priv->chip_type == FT232BM || priv->chip_type == FT2232C) {
                  device_create_file(&udev->dev, &dev_attr_latency_timer);
            }
      }
}

static void remove_sysfs_attrs(struct usb_serial *serial)
{
      struct ftdi_private *priv;
      struct usb_device *udev;

      dbg("%s",__FUNCTION__); 

      priv = usb_get_serial_port_data(serial->port[0]);
      udev = serial->dev;
      
      /* XXX see create_sysfs_attrs */
      if (priv->chip_type != SIO) {
            device_remove_file(&udev->dev, &dev_attr_event_char);
            if (priv->chip_type == FT232BM || priv->chip_type == FT2232C) {
                  device_remove_file(&udev->dev, &dev_attr_latency_timer);
            }
      }
      
}

/*
 * ***************************************************************************
 * FTDI driver specific functions
 * ***************************************************************************
 */

/* Probe function to check for special devices */
static int ftdi_sio_probe (struct usb_serial *serial, const struct usb_device_id *id)
{
      usb_set_serial_data(serial, (void *)id->driver_info);

      return (0);
}

/* attach subroutine */
static int ftdi_sio_attach (struct usb_serial *serial)
{
      struct usb_serial_port *port = serial->port[0];
      struct ftdi_private *priv;
      struct ftdi_sio_quirk *quirk;
      
      dbg("%s",__FUNCTION__);

      priv = kzalloc(sizeof(struct ftdi_private), GFP_KERNEL);
      if (!priv){
            err("%s- kmalloc(%Zd) failed.", __FUNCTION__, sizeof(struct ftdi_private));
            return -ENOMEM;
      }

      spin_lock_init(&priv->rx_lock);
      spin_lock_init(&priv->tx_lock);
        init_waitqueue_head(&priv->delta_msr_wait);
      /* This will push the characters through immediately rather
         than queue a task to deliver them */
      priv->flags = ASYNC_LOW_LATENCY;

      /* Increase the size of read buffers */
      kfree(port->bulk_in_buffer);
      port->bulk_in_buffer = kmalloc (BUFSZ, GFP_KERNEL);
      if (!port->bulk_in_buffer) {
            kfree (priv);
            return -ENOMEM;
      }
      if (port->read_urb) {
            port->read_urb->transfer_buffer = port->bulk_in_buffer;
            port->read_urb->transfer_buffer_length = BUFSZ;
      }

      INIT_WORK(&priv->rx_work, ftdi_process_read, port);

      /* Free port's existing write urb and transfer buffer. */
      if (port->write_urb) {
            usb_free_urb (port->write_urb);
            port->write_urb = NULL;
      }
      kfree(port->bulk_out_buffer);
      port->bulk_out_buffer = NULL;

      usb_set_serial_port_data(serial->port[0], priv);

      ftdi_determine_type (serial->port[0]);
      create_sysfs_attrs(serial);

      /* Check for device requiring special set up. */
      quirk = (struct ftdi_sio_quirk *)usb_get_serial_data(serial);
      if (quirk && quirk->setup) {
            quirk->setup(serial);
      }
      
      return (0);
} /* ftdi_sio_attach */


/* Setup for the USB-UIRT device, which requires hardwired
 * baudrate (38400 gets mapped to 312500) */
/* Called from usbserial:serial_probe */
static void ftdi_USB_UIRT_setup (struct usb_serial *serial)
{
      struct ftdi_private *priv;

      dbg("%s",__FUNCTION__);

      priv = usb_get_serial_port_data(serial->port[0]);
      priv->flags |= ASYNC_SPD_CUST;
      priv->custom_divisor = 77;
      priv->force_baud = B38400;
} /* ftdi_USB_UIRT_setup */

/* Setup for the HE-TIRA1 device, which requires hardwired
 * baudrate (38400 gets mapped to 100000) and RTS-CTS enabled.  */
static void ftdi_HE_TIRA1_setup (struct usb_serial *serial)
{
      struct ftdi_private *priv;

      dbg("%s",__FUNCTION__);

      priv = usb_get_serial_port_data(serial->port[0]);
      priv->flags |= ASYNC_SPD_CUST;
      priv->custom_divisor = 240;
      priv->force_baud = B38400;
      priv->force_rtscts = 1;
} /* ftdi_HE_TIRA1_setup */


/* ftdi_shutdown is called from usbserial:usb_serial_disconnect 
 *   it is called when the usb device is disconnected
 *
 *   usbserial:usb_serial_disconnect
 *      calls __serial_close for each open of the port
 *      shutdown is called then (ie ftdi_shutdown)
 */


static void ftdi_shutdown (struct usb_serial *serial)
{ /* ftdi_shutdown */
      
      struct usb_serial_port *port = serial->port[0];
      struct ftdi_private *priv = usb_get_serial_port_data(port);

      dbg("%s", __FUNCTION__);

      remove_sysfs_attrs(serial);
      
      /* all open ports are closed at this point 
         *    (by usbserial.c:__serial_close, which calls ftdi_close)  
       */

      if (priv) {
            usb_set_serial_port_data(port, NULL);
            kfree(priv);
      }
} /* ftdi_shutdown */


static int  ftdi_open (struct usb_serial_port *port, struct file *filp)
{ /* ftdi_open */
      struct usb_device *dev = port->serial->dev;
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      unsigned long flags;
      
      int result = 0;
      char buf[1]; /* Needed for the usb_control_msg I think */

      dbg("%s", __FUNCTION__);

      spin_lock_irqsave(&priv->tx_lock, flags);
      priv->tx_bytes = 0;
      spin_unlock_irqrestore(&priv->tx_lock, flags);
      spin_lock_irqsave(&priv->rx_lock, flags);
      priv->rx_bytes = 0;
      spin_unlock_irqrestore(&priv->rx_lock, flags);

      if (port->tty)
            port->tty->low_latency = (priv->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

      /* No error checking for this (will get errors later anyway) */
      /* See ftdi_sio.h for description of what is reset */
      usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                  FTDI_SIO_RESET_REQUEST, FTDI_SIO_RESET_REQUEST_TYPE, 
                  FTDI_SIO_RESET_SIO, 
                  priv->interface, buf, 0, WDR_TIMEOUT);

      /* Termios defaults are set by usb_serial_init. We don't change
         port->tty->termios - this would loose speed settings, etc.
         This is same behaviour as serial.c/rs_open() - Kuba */

      /* ftdi_set_termios  will send usb control messages */
      if (port->tty)
            ftdi_set_termios(port, NULL);

      /* FIXME: Flow control might be enabled, so it should be checked -
         we have no control of defaults! */
      /* Turn on RTS and DTR since we are not flow controlling by default */
      set_mctrl(port, TIOCM_DTR | TIOCM_RTS);

      /* Not throttled */
      spin_lock_irqsave(&priv->rx_lock, flags);
      priv->rx_flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
      spin_unlock_irqrestore(&priv->rx_lock, flags);

      /* Start reading from the device */
      priv->rx_processed = 0;
      usb_fill_bulk_urb(port->read_urb, dev,
                  usb_rcvbulkpipe(dev, port->bulk_in_endpointAddress),
                  port->read_urb->transfer_buffer, port->read_urb->transfer_buffer_length,
                  ftdi_read_bulk_callback, port);
      result = usb_submit_urb(port->read_urb, GFP_KERNEL);
      if (result)
            err("%s - failed submitting read urb, error %d", __FUNCTION__, result);


      return result;
} /* ftdi_open */



/* 
 * usbserial:__serial_close  only calls ftdi_close if the point is open
 *
 *   This only gets called when it is the last close
 *   
 *   
 */

static void ftdi_close (struct usb_serial_port *port, struct file *filp)
{ /* ftdi_close */
      unsigned int c_cflag = port->tty->termios->c_cflag;
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      char buf[1];

      dbg("%s", __FUNCTION__);

      if (c_cflag & HUPCL){
            /* Disable flow control */
            if (usb_control_msg(port->serial->dev, 
                            usb_sndctrlpipe(port->serial->dev, 0),
                            FTDI_SIO_SET_FLOW_CTRL_REQUEST,
                            FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
                            0, priv->interface, buf, 0,
                            WDR_TIMEOUT) < 0) {
                  err("error from flowcontrol urb");
            }         

            /* drop RTS and DTR */
            clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
      } /* Note change no line if hupcl is off */

      /* cancel any scheduled reading */
      cancel_delayed_work(&priv->rx_work);
      flush_scheduled_work();
      
      /* shutdown our bulk read */
      if (port->read_urb)
            usb_kill_urb(port->read_urb);
} /* ftdi_close */


  
/* The SIO requires the first byte to have:
 *  B0 1
 *  B1 0
 *  B2..7 length of message excluding byte 0
 *
 * The new devices do not require this byte
 */
static int ftdi_write (struct usb_serial_port *port,
                     const unsigned char *buf, int count)
{ /* ftdi_write */
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      struct urb *urb;
      unsigned char *buffer;
      int data_offset ;       /* will be 1 for the SIO and 0 otherwise */
      int status;
      int transfer_size;
      unsigned long flags;

      dbg("%s port %d, %d bytes", __FUNCTION__, port->number, count);

      if (count == 0) {
            dbg("write request of 0 bytes");
            return 0;
      }
      spin_lock_irqsave(&priv->tx_lock, flags);
      if (priv->tx_outstanding_urbs > URB_UPPER_LIMIT) {
            spin_unlock_irqrestore(&priv->tx_lock, flags);
            dbg("%s - write limit hit\n", __FUNCTION__);
            return 0;
      }
      spin_unlock_irqrestore(&priv->tx_lock, flags);
      
      data_offset = priv->write_offset;
        dbg("data_offset set to %d",data_offset);

      /* Determine total transfer size */
      transfer_size = count;
      if (data_offset > 0) {
            /* Original sio needs control bytes too... */
            transfer_size += (data_offset *
                        ((count + (PKTSZ - 1 - data_offset)) /
                         (PKTSZ - data_offset)));
      }

      buffer = kmalloc (transfer_size, GFP_ATOMIC);
      if (!buffer) {
            err("%s ran out of kernel memory for urb ...", __FUNCTION__);
            return -ENOMEM;
      }

      urb = usb_alloc_urb(0, GFP_ATOMIC);
      if (!urb) {
            err("%s - no more free urbs", __FUNCTION__);
            kfree (buffer);
            return -ENOMEM;
      }

      /* Copy data */
      if (data_offset > 0) {
            /* Original sio requires control byte at start of each packet. */
            int user_pktsz = PKTSZ - data_offset;
            int todo = count;
            unsigned char *first_byte = buffer;
            const unsigned char *current_position = buf;

            while (todo > 0) {
                  if (user_pktsz > todo) {
                        user_pktsz = todo;
                  }
                  /* Write the control byte at the front of the packet*/
                  *first_byte = 1 | ((user_pktsz) << 2); 
                  /* Copy data for packet */
                  memcpy (first_byte + data_offset,
                        current_position, user_pktsz);
                  first_byte += user_pktsz + data_offset;
                  current_position += user_pktsz;
                  todo -= user_pktsz;
            }
      } else {
            /* No control byte required. */
            /* Copy in the data to send */
            memcpy (buffer, buf, count);
      }

      usb_serial_debug_data(debug, &port->dev, __FUNCTION__, transfer_size, buffer);

      /* fill the buffer and send it */
      usb_fill_bulk_urb(urb, port->serial->dev, 
                  usb_sndbulkpipe(port->serial->dev, port->bulk_out_endpointAddress),
                  buffer, transfer_size,
                  ftdi_write_bulk_callback, port);

      status = usb_submit_urb(urb, GFP_ATOMIC);
      if (status) {
            err("%s - failed submitting write urb, error %d", __FUNCTION__, status);
            count = status;
            kfree (buffer);
      } else {
            spin_lock_irqsave(&priv->tx_lock, flags);
            ++priv->tx_outstanding_urbs;
            priv->tx_outstanding_bytes += count;
            priv->tx_bytes += count;
            spin_unlock_irqrestore(&priv->tx_lock, flags);
      }

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

      dbg("%s write returning: %d", __FUNCTION__, count);
      return count;
} /* ftdi_write */


/* This function may get called when the device is closed */

static void ftdi_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
{
      unsigned long flags;
      struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
      struct ftdi_private *priv;
      int data_offset;       /* will be 1 for the SIO and 0 otherwise */
      unsigned long countback;

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

      dbg("%s - port %d", __FUNCTION__, port->number);
      
      if (urb->status) {
            dbg("nonzero write bulk status received: %d", urb->status);
            return;
      }

      priv = usb_get_serial_port_data(port);
      if (!priv) {
            dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
            return;
      }
      /* account for transferred data */
      countback = urb->actual_length;
      data_offset = priv->write_offset;
      if (data_offset > 0) {
            /* Subtract the control bytes */
            countback -= (data_offset * ((countback + (PKTSZ - 1)) / PKTSZ));
      }
      spin_lock_irqsave(&priv->tx_lock, flags);
      --priv->tx_outstanding_urbs;
      priv->tx_outstanding_bytes -= countback;
      spin_unlock_irqrestore(&priv->tx_lock, flags);

      usb_serial_port_softint(port);
} /* ftdi_write_bulk_callback */


static int ftdi_write_room( struct usb_serial_port *port )
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      int room;
      unsigned long flags;

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

      spin_lock_irqsave(&priv->tx_lock, flags);
      if (priv->tx_outstanding_urbs < URB_UPPER_LIMIT) {
            /*
             * We really can take anything the user throws at us
             * but let's pick a nice big number to tell the tty
             * layer that we have lots of free space
             */
            room = 2048;
      } else {
            room = 0;
      }
      spin_unlock_irqrestore(&priv->tx_lock, flags);
      return room;
} /* ftdi_write_room */


static int ftdi_chars_in_buffer (struct usb_serial_port *port)
{ /* ftdi_chars_in_buffer */
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      int buffered;
      unsigned long flags;

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

      spin_lock_irqsave(&priv->tx_lock, flags);
      buffered = (int)priv->tx_outstanding_bytes;
      spin_unlock_irqrestore(&priv->tx_lock, flags);
      if (buffered < 0) {
            err("%s outstanding tx bytes is negative!", __FUNCTION__);
            buffered = 0;
      }
      return buffered;
} /* ftdi_chars_in_buffer */



static void ftdi_read_bulk_callback (struct urb *urb, struct pt_regs *regs)
{ /* ftdi_read_bulk_callback */
      struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
      struct tty_struct *tty;
      struct ftdi_private *priv;
      unsigned long countread;
      unsigned long flags;

      if (urb->number_of_packets > 0) {
            err("%s transfer_buffer_length %d actual_length %d number of packets %d",__FUNCTION__,
                urb->transfer_buffer_length, urb->actual_length, urb->number_of_packets );
            err("%s transfer_flags %x ", __FUNCTION__,urb->transfer_flags );
      }

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

      if (port->open_count <= 0)
            return;

      tty = port->tty;
      if (!tty) {
            dbg("%s - bad tty pointer - exiting",__FUNCTION__);
            return;
      }

      priv = usb_get_serial_port_data(port);
      if (!priv) {
            dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
            return;
      }

      if (urb != port->read_urb) {
            err("%s - Not my urb!", __FUNCTION__);
      }

      if (urb->status) {
            /* This will happen at close every time so it is a dbg not an err */
            dbg("(this is ok on close) nonzero read bulk status received: %d", urb->status);
            return;
      }

      /* count data bytes, but not status bytes */
      countread = urb->actual_length;
      countread -= 2 * ((countread + (PKTSZ - 1)) / PKTSZ);
      spin_lock_irqsave(&priv->rx_lock, flags);
      priv->rx_bytes += countread;
      spin_unlock_irqrestore(&priv->rx_lock, flags);

      ftdi_process_read(port);

} /* ftdi_read_bulk_callback */


static void ftdi_process_read (void *param)
{ /* ftdi_process_read */
      struct usb_serial_port *port = (struct usb_serial_port*)param;
      struct urb *urb;
      struct tty_struct *tty;
      struct ftdi_private *priv;
      char error_flag;
            unsigned char *data;

      int i;
      int result;
      int need_flip;
      int packet_offset;
      unsigned long flags;

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

      if (port->open_count <= 0)
            return;

      tty = port->tty;
      if (!tty) {
            dbg("%s - bad tty pointer - exiting",__FUNCTION__);
            return;
      }

      priv = usb_get_serial_port_data(port);
      if (!priv) {
            dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
            return;
      }

      urb = port->read_urb;
      if (!urb) {
            dbg("%s - bad read_urb pointer - exiting", __FUNCTION__);
            return;
      }

      data = urb->transfer_buffer;

      if (priv->rx_processed) {
            dbg("%s - already processed: %d bytes, %d remain", __FUNCTION__,
                        priv->rx_processed,
                        urb->actual_length - priv->rx_processed);
      } else {
            /* The first two bytes of every read packet are status */
            if (urb->actual_length > 2) {
                  usb_serial_debug_data(debug, &port->dev, __FUNCTION__, urb->actual_length, data);
            } else {
                  dbg("Status only: %03oo %03oo",data[0],data[1]);
            }
      }


      /* TO DO -- check for hung up line and handle appropriately: */
      /*   send hangup  */
      /* See acm.c - you do a tty_hangup  - eg tty_hangup(tty) */
      /* if CD is dropped and the line is not CLOCAL then we should hangup */

      need_flip = 0;
      for (packet_offset = priv->rx_processed; packet_offset < urb->actual_length; packet_offset += PKTSZ) {
            int length;

            /* Compare new line status to the old one, signal if different */
            /* N.B. packet may be processed more than once, but differences
             * are only processed once.  */
            if (priv != NULL) {
                  char new_status = data[packet_offset+0] & FTDI_STATUS_B0_MASK;
                  if (new_status != priv->prev_status) {
                        priv->diff_status |= new_status ^ priv->prev_status;
                        wake_up_interruptible(&priv->delta_msr_wait);
                        priv->prev_status = new_status;
                  }
            }

            length = min(PKTSZ, urb->actual_length-packet_offset)-2;
            if (length < 0) {
                  err("%s - bad packet length: %d", __FUNCTION__, length+2);
                  length = 0;
            }

            if (priv->rx_flags & THROTTLED) {
                  dbg("%s - throttled", __FUNCTION__);
                  break;
            }
            if (tty_buffer_request_room(tty, length) < length) {
                  /* break out & wait for throttling/unthrottling to happen */
                  dbg("%s - receive room low", __FUNCTION__);
                  break;
            }

            /* Handle errors and break */
            error_flag = TTY_NORMAL;
            /* Although the device uses a bitmask and hence can have multiple */
            /* errors on a packet - the order here sets the priority the */
            /* error is returned to the tty layer  */

            if ( data[packet_offset+1] & FTDI_RS_OE ) {
                  error_flag = TTY_OVERRUN;
                  dbg("OVERRRUN error");
            }
            if ( data[packet_offset+1] & FTDI_RS_BI ) {
                  error_flag = TTY_BREAK;
                  dbg("BREAK received");
            }
            if ( data[packet_offset+1] & FTDI_RS_PE ) {
                  error_flag = TTY_PARITY;
                  dbg("PARITY error");
            }
            if ( data[packet_offset+1] & FTDI_RS_FE ) {
                  error_flag = TTY_FRAME;
                  dbg("FRAMING error");
            }
            if (length > 0) {
                  for (i = 2; i < length+2; i++) {
                        /* Note that the error flag is duplicated for 
                           every character received since we don't know
                           which character it applied to */
                        tty_insert_flip_char(tty, data[packet_offset+i], error_flag);
                  }
                  need_flip = 1;
            }

#ifdef NOT_CORRECT_BUT_KEEPING_IT_FOR_NOW
            /* if a parity error is detected you get status packets forever
               until a character is sent without a parity error.
               This doesn't work well since the application receives a never
               ending stream of bad data - even though new data hasn't been sent.
               Therefore I (bill) have taken this out.
               However - this might make sense for framing errors and so on 
               so I am leaving the code in for now.
            */
            else {
                  if (error_flag != TTY_NORMAL){
                        dbg("error_flag is not normal");
                        /* In this case it is just status - if that is an error send a bad character */
                        if(tty->flip.count >= TTY_FLIPBUF_SIZE) {
                              tty_flip_buffer_push(tty);
                        }
                        tty_insert_flip_char(tty, 0xff, error_flag);
                        need_flip = 1;
                  }
            }
#endif
      } /* "for(packet_offset=0..." */

      /* Low latency */
      if (need_flip) {
            tty_flip_buffer_push(tty);
      }

      if (packet_offset < urb->actual_length) {
            /* not completely processed - record progress */
            priv->rx_processed = packet_offset;
            dbg("%s - incomplete, %d bytes processed, %d remain",
                        __FUNCTION__, packet_offset,
                        urb->actual_length - packet_offset);
            /* check if we were throttled while processing */
            spin_lock_irqsave(&priv->rx_lock, flags);
            if (priv->rx_flags & THROTTLED) {
                  priv->rx_flags |= ACTUALLY_THROTTLED;
                  spin_unlock_irqrestore(&priv->rx_lock, flags);
                  dbg("%s - deferring remainder until unthrottled",
                              __FUNCTION__);
                  return;
            }
            spin_unlock_irqrestore(&priv->rx_lock, flags);
            /* if the port is closed stop trying to read */
            if (port->open_count > 0){
                  /* delay processing of remainder */
                  schedule_delayed_work(&priv->rx_work, 1);
            } else {
                  dbg("%s - port is closed", __FUNCTION__);
            }
            return;
      }

      /* urb is completely processed */
      priv->rx_processed = 0;

      /* if the port is closed stop trying to read */
      if (port->open_count > 0){
            /* 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,
                        ftdi_read_bulk_callback, port);

            result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
            if (result)
                  err("%s - failed resubmitting read urb, error %d", __FUNCTION__, result);
      }

      return;
} /* ftdi_process_read */


static void ftdi_break_ctl( struct usb_serial_port *port, int break_state )
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      __u16 urb_value = 0; 
      char buf[1];
      
      /* break_state = -1 to turn on break, and 0 to turn off break */
      /* see drivers/char/tty_io.c to see it used */
      /* last_set_data_urb_value NEVER has the break bit set in it */

      if (break_state) {
            urb_value = priv->last_set_data_urb_value | FTDI_SIO_SET_BREAK;
      } else {
            urb_value = priv->last_set_data_urb_value; 
      }

      
      if (usb_control_msg(port->serial->dev, usb_sndctrlpipe(port->serial->dev, 0),
                      FTDI_SIO_SET_DATA_REQUEST, 
                      FTDI_SIO_SET_DATA_REQUEST_TYPE,
                      urb_value , priv->interface,
                      buf, 0, WDR_TIMEOUT) < 0) {
            err("%s FAILED to enable/disable break state (state was %d)", __FUNCTION__,break_state);
      }        

      dbg("%s break state is %d - urb is %d", __FUNCTION__,break_state, urb_value);
      
}


/* old_termios contains the original termios settings and tty->termios contains
 * the new setting to be used
 * WARNING: set_termios calls this with old_termios in kernel space
 */

static void ftdi_set_termios (struct usb_serial_port *port, struct termios *old_termios)
{ /* ftdi_termios */
      struct usb_device *dev = port->serial->dev;
      unsigned int cflag = port->tty->termios->c_cflag;
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      __u16 urb_value; /* will hold the new flags */
      char buf[1]; /* Perhaps I should dynamically alloc this? */
      
      // Added for xon/xoff support
      unsigned int iflag = port->tty->termios->c_iflag;
      unsigned char vstop;
      unsigned char vstart;
      
      dbg("%s", __FUNCTION__);

      /* Force baud rate if this device requires it, unless it is set to B0. */
      if (priv->force_baud && ((port->tty->termios->c_cflag & CBAUD) != B0)) {
            dbg("%s: forcing baud rate for this device", __FUNCTION__);
            port->tty->termios->c_cflag &= ~CBAUD;
            port->tty->termios->c_cflag |= priv->force_baud;
      }

      /* Force RTS-CTS if this device requires it. */
      if (priv->force_rtscts) {
            dbg("%s: forcing rtscts for this device", __FUNCTION__);
            port->tty->termios->c_cflag |= CRTSCTS;
      }

      cflag = port->tty->termios->c_cflag;

      /* FIXME -For this cut I don't care if the line is really changing or 
         not  - so just do the change regardless  - should be able to 
         compare old_termios and tty->termios */
      /* NOTE These routines can get interrupted by 
         ftdi_sio_read_bulk_callback  - need to examine what this 
           means - don't see any problems yet */
      
      /* Set number of data bits, parity, stop bits */
      
      urb_value = 0;
      urb_value |= (cflag & CSTOPB ? FTDI_SIO_SET_DATA_STOP_BITS_2 :
                  FTDI_SIO_SET_DATA_STOP_BITS_1);
      urb_value |= (cflag & PARENB ? 
                  (cflag & PARODD ? FTDI_SIO_SET_DATA_PARITY_ODD : 
                   FTDI_SIO_SET_DATA_PARITY_EVEN) :
                  FTDI_SIO_SET_DATA_PARITY_NONE);
      if (cflag & CSIZE) {
            switch (cflag & CSIZE) {
            case CS5: urb_value |= 5; dbg("Setting CS5"); break;
            case CS6: urb_value |= 6; dbg("Setting CS6"); break;
            case CS7: urb_value |= 7; dbg("Setting CS7"); break;
            case CS8: urb_value |= 8; dbg("Setting CS8"); break;
            default:
                  err("CSIZE was set but not CS5-CS8");
            }
      }

      /* This is needed by the break command since it uses the same command - but is
       *  or'ed with this value  */
      priv->last_set_data_urb_value = urb_value;
      
      if (usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                      FTDI_SIO_SET_DATA_REQUEST, 
                      FTDI_SIO_SET_DATA_REQUEST_TYPE,
                      urb_value , priv->interface,
                      buf, 0, WDR_SHORT_TIMEOUT) < 0) {
            err("%s FAILED to set databits/stopbits/parity", __FUNCTION__);
      }        

      /* Now do the baudrate */
      if ((cflag & CBAUD) == B0 ) {
            /* Disable flow control */
            if (usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                            FTDI_SIO_SET_FLOW_CTRL_REQUEST, 
                            FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
                            0, priv->interface, 
                            buf, 0, WDR_TIMEOUT) < 0) {
                  err("%s error from disable flowcontrol urb", __FUNCTION__);
            }         
            /* Drop RTS and DTR */
            clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
      } else {
            /* set the baudrate determined before */
            if (change_speed(port)) {
                  err("%s urb failed to set baudrate", __FUNCTION__);
            }
            /* Ensure RTS and DTR are raised when baudrate changed from 0 */
            if (!old_termios || (old_termios->c_cflag & CBAUD) == B0) {
                  set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
            }
      }

      /* Set flow control */
      /* Note device also supports DTR/CD (ugh) and Xon/Xoff in hardware */
      if (cflag & CRTSCTS) {
            dbg("%s Setting to CRTSCTS flow control", __FUNCTION__);
            if (usb_control_msg(dev, 
                            usb_sndctrlpipe(dev, 0),
                            FTDI_SIO_SET_FLOW_CTRL_REQUEST, 
                            FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
                            0 , (FTDI_SIO_RTS_CTS_HS | priv->interface),
                            buf, 0, WDR_TIMEOUT) < 0) {
                  err("urb failed to set to rts/cts flow control");
            }           
            
      } else { 
            /*
             * Xon/Xoff code
             *
             * Check the IXOFF status in the iflag component of the termios structure
             * if IXOFF is not set, the pre-xon/xoff code is executed.
            */
            if (iflag & IXOFF) {
                  dbg("%s  request to enable xonxoff iflag=%04x",__FUNCTION__,iflag);
                  // Try to enable the XON/XOFF on the ftdi_sio
                  // Set the vstart and vstop -- could have been done up above where
                  // a lot of other dereferencing is done but that would be very
                  // inefficient as vstart and vstop are not always needed
                  vstart=port->tty->termios->c_cc[VSTART];
                  vstop=port->tty->termios->c_cc[VSTOP];
                  urb_value=(vstop << 8) | (vstart);

                  if (usb_control_msg(dev,
                                  usb_sndctrlpipe(dev, 0),
                                  FTDI_SIO_SET_FLOW_CTRL_REQUEST,
                                  FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
                                  urb_value , (FTDI_SIO_XON_XOFF_HS
                                           | priv->interface),
                                  buf, 0, WDR_TIMEOUT) < 0) {
                        err("urb failed to set to xon/xoff flow control");
                  }
            } else {
                  /* else clause to only run if cfag ! CRTSCTS and iflag ! XOFF */
                  /* CHECKME Assuming XON/XOFF handled by tty stack - not by device */
                  dbg("%s Turning off hardware flow control", __FUNCTION__);
                  if (usb_control_msg(dev, 
                                  usb_sndctrlpipe(dev, 0),
                                  FTDI_SIO_SET_FLOW_CTRL_REQUEST, 
                                  FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
                                  0, priv->interface, 
                                  buf, 0, WDR_TIMEOUT) < 0) {
                        err("urb failed to clear flow control");
                  }                       
            }
            
      }
      return;
} /* ftdi_termios */


static int ftdi_tiocmget (struct usb_serial_port *port, struct file *file)
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      unsigned char buf[2];
      int ret;

      dbg("%s TIOCMGET", __FUNCTION__);
      switch (priv->chip_type) {
      case SIO:
            /* Request the status from the device */
            if ((ret = usb_control_msg(port->serial->dev, 
                                 usb_rcvctrlpipe(port->serial->dev, 0),
                                 FTDI_SIO_GET_MODEM_STATUS_REQUEST, 
                                 FTDI_SIO_GET_MODEM_STATUS_REQUEST_TYPE,
                                 0, 0, 
                                 buf, 1, WDR_TIMEOUT)) < 0 ) {
                  err("%s Could not get modem status of device - err: %d", __FUNCTION__,
                      ret);
                  return(ret);
            }
            break;
      case FT8U232AM:
      case FT232BM:
      case FT2232C:
            /* the 8U232AM returns a two byte value (the sio is a 1 byte value) - in the same
               format as the data returned from the in point */
            if ((ret = usb_control_msg(port->serial->dev, 
                                 usb_rcvctrlpipe(port->serial->dev, 0),
                                 FTDI_SIO_GET_MODEM_STATUS_REQUEST, 
                                 FTDI_SIO_GET_MODEM_STATUS_REQUEST_TYPE,
                                 0, priv->interface, 
                                 buf, 2, WDR_TIMEOUT)) < 0 ) {
                  err("%s Could not get modem status of device - err: %d", __FUNCTION__,
                      ret);
                  return(ret);
            }
            break;
      default:
            return -EFAULT;
            break;
      }
      
      return  (buf[0] & FTDI_SIO_DSR_MASK ? TIOCM_DSR : 0) |
            (buf[0] & FTDI_SIO_CTS_MASK ? TIOCM_CTS : 0) |
            (buf[0]  & FTDI_SIO_RI_MASK  ? TIOCM_RI  : 0) |
            (buf[0]  & FTDI_SIO_RLSD_MASK ? TIOCM_CD  : 0) |
            priv->last_dtr_rts;                 
}

static int ftdi_tiocmset(struct usb_serial_port *port, struct file * file, unsigned int set, unsigned int clear)
{
      dbg("%s TIOCMSET", __FUNCTION__);
      return update_mctrl(port, set, clear);
}


static int ftdi_ioctl (struct usb_serial_port *port, struct file * file, unsigned int cmd, unsigned long arg)
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);

      dbg("%s cmd 0x%04x", __FUNCTION__, cmd);

      /* Based on code from acm.c and others */
      switch (cmd) {

      case TIOCGSERIAL: /* gets serial port data */
            return get_serial_info(port, (struct serial_struct __user *) arg);

      case TIOCSSERIAL: /* sets serial port data */
            return set_serial_info(port, (struct serial_struct __user *) arg);

      /*
       * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
       * - mask passed in arg for lines of interest
       *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
       * Caller should use TIOCGICOUNT to see which one it was.
       *
       * This code is borrowed from linux/drivers/char/serial.c
       */
      case TIOCMIWAIT:
            while (priv != NULL) {
                  interruptible_sleep_on(&priv->delta_msr_wait);
                  /* see if a signal did it */
                  if (signal_pending(current))
                        return -ERESTARTSYS;
                  else {
                        char diff = priv->diff_status;

                        if (diff == 0) {
                              return -EIO; /* no change => error */
                        }

                        /* Consume all events */
                        priv->diff_status = 0;

                        /* Return 0 if caller wanted to know about these bits */
                        if ( ((arg & TIOCM_RNG) && (diff & FTDI_RS0_RI)) ||
                             ((arg & TIOCM_DSR) && (diff & FTDI_RS0_DSR)) ||
                             ((arg & TIOCM_CD)  && (diff & FTDI_RS0_RLSD)) ||
                             ((arg & TIOCM_CTS) && (diff & FTDI_RS0_CTS)) ) {
                              return 0;
                        }
                        /*
                         * Otherwise caller can't care less about what happened,
                         * and so we continue to wait for more events.
                         */
                  }
            }
            return(0);
            break;
      default:
            break;
            
      }


      /* This is not necessarily an error - turns out the higher layers will do 
       *  some ioctls itself (see comment above)
       */
      dbg("%s arg not supported - it was 0x%04x - check /usr/include/asm/ioctls.h", __FUNCTION__, cmd);

      return(-ENOIOCTLCMD);
} /* ftdi_ioctl */


static void ftdi_throttle (struct usb_serial_port *port)
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      unsigned long flags;

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

      spin_lock_irqsave(&priv->rx_lock, flags);
      priv->rx_flags |= THROTTLED;
      spin_unlock_irqrestore(&priv->rx_lock, flags);
}


static void ftdi_unthrottle (struct usb_serial_port *port)
{
      struct ftdi_private *priv = usb_get_serial_port_data(port);
      int actually_throttled;
      unsigned long flags;

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

      spin_lock_irqsave(&priv->rx_lock, flags);
      actually_throttled = priv->rx_flags & ACTUALLY_THROTTLED;
      priv->rx_flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
      spin_unlock_irqrestore(&priv->rx_lock, flags);

      if (actually_throttled)
            schedule_work(&priv->rx_work);
}

static int __init ftdi_init (void)
{
      int retval;

      dbg("%s", __FUNCTION__);
      if (vendor > 0 && product > 0) {
            /* Add user specified VID/PID to reserved element of table. */
            int i;
            for (i = 0; id_table_combined[i].idVendor; i++)
                  ;
            id_table_combined[i].match_flags = USB_DEVICE_ID_MATCH_DEVICE;
            id_table_combined[i].idVendor = vendor;
            id_table_combined[i].idProduct = product;
      }
      retval = usb_serial_register(&ftdi_sio_device);
      if (retval)
            goto failed_sio_register;
      retval = usb_register(&ftdi_driver);
      if (retval) 
            goto failed_usb_register;

      info(DRIVER_VERSION ":" DRIVER_DESC);
      return 0;
failed_usb_register:
      usb_serial_deregister(&ftdi_sio_device);
failed_sio_register:
      return retval;
}


static void __exit ftdi_exit (void)
{

      dbg("%s", __FUNCTION__);

      usb_deregister (&ftdi_driver);
      usb_serial_deregister (&ftdi_sio_device);

}


module_init(ftdi_init);
module_exit(ftdi_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");
module_param(vendor, ushort, 0);
MODULE_PARM_DESC(vendor, "User specified vendor ID (default="
            __MODULE_STRING(FTDI_VID)")");
module_param(product, ushort, 0);
MODULE_PARM_DESC(vendor, "User specified product ID");


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