Quelle  io_edgeport.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0+
/*
 * Edgeport USB Serial Converter driver
 *
 * Copyright (C) 2000 Inside Out Networks, All rights reserved.
 * Copyright (C) 2001-2002 Greg Kroah-Hartman <greg@kroah.com>
 *
 * Supports the following devices:
 * Edgeport/4
 * Edgeport/4t
 * Edgeport/2
 * Edgeport/4i
 * Edgeport/2i
 * Edgeport/421
 * Edgeport/21
 * Rapidport/4
 * Edgeport/8
 * Edgeport/2D8
 * Edgeport/4D8
 * Edgeport/8i
 *
 * For questions or problems with this driver, contact Inside Out
 * Networks technical support, or Peter Berger <pberger@brimson.com>,
 * or Al Borchers <alborchers@steinerpoint.com>.
 *
 */

#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/errno.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/serial.h>
#include <linux/ioctl.h>
#include <linux/wait.h>
#include <linux/firmware.h>
#include <linux/ihex.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include "io_edgeport.h"
#include "io_ionsp.h"  /* info for the iosp messages */
#include "io_16654.h"  /* 16654 UART defines */

#define DRIVER_AUTHOR "Greg Kroah-Hartman and David Iacovelli"
#define DRIVER_DESC "Edgeport USB Serial Driver"

#define MAX_NAME_LEN  64

#define OPEN_TIMEOUT  (5*HZ)  /* 5 seconds */

static const struct usb_device_id edgeport_2port_id_table[] = {
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_2) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_2I) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_421) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_21) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_2_DIN) },
 { }
};

static const struct usb_device_id edgeport_4port_id_table[] = {
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_4) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_RAPIDPORT_4) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_4T) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_MT4X56USB) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_4I) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8_DUAL_CPU) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_4_DIN) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_22I) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_412_4) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_COMPATIBLE) },
 { }
};

static const struct usb_device_id edgeport_8port_id_table[] = {
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_16_DUAL_CPU) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8I) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8R) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8RR) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_412_8) },
 { }
};

static const struct usb_device_id Epic_port_id_table[] = {
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0202) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0203) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0310) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0311) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0312) },
 { USB_DEVICE(USB_VENDOR_ID_AXIOHM, AXIOHM_DEVICE_ID_EPIC_A758) },
 { USB_DEVICE(USB_VENDOR_ID_AXIOHM, AXIOHM_DEVICE_ID_EPIC_A794) },
 { USB_DEVICE(USB_VENDOR_ID_AXIOHM, AXIOHM_DEVICE_ID_EPIC_A225) },
 { }
};

/* Devices that this driver supports */
static const struct usb_device_id id_table_combined[] = {
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_4) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_RAPIDPORT_4) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_4T) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_MT4X56USB) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_2) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_4I) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_2I) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_421) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_21) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8_DUAL_CPU) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_2_DIN) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_4_DIN) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_16_DUAL_CPU) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_22I) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_412_4) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_COMPATIBLE) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8I) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8R) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_8RR) },
 { USB_DEVICE(USB_VENDOR_ID_ION, ION_DEVICE_ID_EDGEPORT_412_8) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0202) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0203) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0310) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0311) },
 { USB_DEVICE(USB_VENDOR_ID_NCR, NCR_DEVICE_ID_EPIC_0312) },
 { USB_DEVICE(USB_VENDOR_ID_AXIOHM, AXIOHM_DEVICE_ID_EPIC_A758) },
 { USB_DEVICE(USB_VENDOR_ID_AXIOHM, AXIOHM_DEVICE_ID_EPIC_A794) },
 { USB_DEVICE(USB_VENDOR_ID_AXIOHM, AXIOHM_DEVICE_ID_EPIC_A225) },
 { } /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, id_table_combined);


/* receive port state */
enum RXSTATE {
 EXPECT_HDR1 = 0,    /* Expect header byte 1 */
 EXPECT_HDR2 = 1,    /* Expect header byte 2 */
 EXPECT_DATA = 2,    /* Expect 'RxBytesRemaining' data */
 EXPECT_HDR3 = 3,    /* Expect header byte 3 (for status hdrs only) */
};


/* Transmit Fifo
 * This Transmit queue is an extension of the edgeport Rx buffer.
 * The maximum amount of data buffered in both the edgeport
 * Rx buffer (maxTxCredits) and this buffer will never exceed maxTxCredits.
 */
struct TxFifo {
 unsigned int head; /* index to head pointer (write) */
 unsigned int tail; /* index to tail pointer (read)  */
 unsigned int count; /* Bytes in queue */
 unsigned int size; /* Max size of queue (equal to Max number of TxCredits) */
 unsigned char *fifo; /* allocated Buffer */
};

/* This structure holds all of the local port information */
struct edgeport_port {
 __u16   txCredits;  /* our current credits for this port */
 __u16   maxTxCredits;  /* the max size of the port */

 struct TxFifo  txfifo;   /* transmit fifo -- size will be maxTxCredits */
 struct urb  *write_urb;  /* write URB for this port */
 bool   write_in_progress; /* 'true' while a write URB is outstanding */
 spinlock_t  ep_lock;

 __u8   shadowLCR;  /* last LCR value received */
 __u8   shadowMCR;  /* last MCR value received */
 __u8   shadowMSR;  /* last MSR value received */
 __u8   shadowLSR;  /* last LSR value received */
 __u8   shadowXonChar;  /* last value set as XON char in Edgeport */
 __u8   shadowXoffChar;  /* last value set as XOFF char in Edgeport */
 __u8   validDataMask;
 __u32   baudRate;

 bool   open;
 bool   openPending;
 bool   commandPending;
 bool   closePending;
 bool   chaseResponsePending;

 wait_queue_head_t wait_chase;  /* for handling sleeping while waiting for chase to finish */
 wait_queue_head_t wait_open;  /* for handling sleeping while waiting for open to finish */
 wait_queue_head_t wait_command;  /* for handling sleeping while waiting for command to finish */

 struct usb_serial_port *port;   /* loop back to the owner of this object */
};


/* This structure holds all of the individual device information */
struct edgeport_serial {
 char   name[MAX_NAME_LEN+2];  /* string name of this device */

 struct edge_manuf_descriptor manuf_descriptor; /* the manufacturer descriptor */
 struct edge_boot_descriptor boot_descriptor; /* the boot firmware descriptor */
 struct edgeport_product_info product_info;  /* Product Info */
 struct edge_compatibility_descriptor epic_descriptor; /* Edgeport compatible descriptor */
 int   is_epic;   /* flag if EPiC device or not */

 __u8   interrupt_in_endpoint;  /* the interrupt endpoint handle */
 unsigned char  *interrupt_in_buffer;  /* the buffer we use for the interrupt endpoint */
 struct urb  *interrupt_read_urb;  /* our interrupt urb */

 __u8   bulk_in_endpoint;  /* the bulk in endpoint handle */
 unsigned char  *bulk_in_buffer;  /* the buffer we use for the bulk in endpoint */
 struct urb  *read_urb;   /* our bulk read urb */
 bool   read_in_progress;
 spinlock_t  es_lock;

 __u8   bulk_out_endpoint;  /* the bulk out endpoint handle */

 __s16   rxBytesAvail;   /* the number of bytes that we need to read from this device */

 enum RXSTATE  rxState;   /* the current state of the bulk receive processor */
 __u8   rxHeader1;   /* receive header byte 1 */
 __u8   rxHeader2;   /* receive header byte 2 */
 __u8   rxHeader3;   /* receive header byte 3 */
 __u8   rxPort;    /* the port that we are currently receiving data for */
 __u8   rxStatusCode;   /* the receive status code */
 __u8   rxStatusParam;   /* the receive status parameter */
 __s16   rxBytesRemaining;  /* the number of port bytes left to read */
 struct usb_serial *serial;   /* loop back to the owner of this object */
};

/* baud rate information */
struct divisor_table_entry {
 __u32   BaudRate;
 __u16  Divisor;
};

/*
 * Define table of divisors for Rev A EdgePort/4 hardware
 * These assume a 3.6864MHz crystal, the standard /16, and
 * MCR.7 = 0.
 */

static const struct divisor_table_entry divisor_table[] = {
 {   50,  4608},
 {   75,  3072},
 {   110, 2095}, /* 2094.545455 => 230450   => .0217 % over */
 {   134, 1713}, /* 1713.011152 => 230398.5 => .00065% under */
 {   150, 1536},
 {   300, 768},
 {   600, 384},
 {   1200, 192},
 {   1800, 128},
 {   2400, 96},
 {   4800, 48},
 {   7200, 32},
 {   9600, 24},
 {   14400, 16},
 {   19200, 12},
 {   38400, 6},
 {   57600, 4},
 {   115200, 2},
 {   230400, 1},
};

/* Number of outstanding Command Write Urbs */
static atomic_t CmdUrbs = ATOMIC_INIT(0);


/* function prototypes */

static void edge_close(struct usb_serial_port *port);

static void  process_rcvd_data(struct edgeport_serial *edge_serial,
    unsigned char *buffer, __u16 bufferLength);
static void process_rcvd_status(struct edgeport_serial *edge_serial,
    __u8 byte2, __u8 byte3);
static void edge_tty_recv(struct usb_serial_port *port, unsigned char *data,
  int length);
static void handle_new_msr(struct edgeport_port *edge_port, __u8 newMsr);
static void handle_new_lsr(struct edgeport_port *edge_port, __u8 lsrData,
    __u8 lsr, __u8 data);
static int  send_iosp_ext_cmd(struct edgeport_port *edge_port, __u8 command,
    __u8 param);
static int  calc_baud_rate_divisor(struct device *dev, int baud_rate, int *divisor);
static void change_port_settings(struct tty_struct *tty,
    struct edgeport_port *edge_port,
    const struct ktermios *old_termios);
static int  send_cmd_write_uart_register(struct edgeport_port *edge_port,
    __u8 regNum, __u8 regValue);
static int  write_cmd_usb(struct edgeport_port *edge_port,
    unsigned char *buffer, int writeLength);
static void send_more_port_data(struct edgeport_serial *edge_serial,
    struct edgeport_port *edge_port);

static int rom_write(struct usb_serial *serial, __u16 extAddr, __u16 addr,
     __u16 length, const __u8 *data);

/* ************************************************************************ */
/* ************************************************************************ */
/* ************************************************************************ */
/* ************************************************************************ */

/************************************************************************
 * *
 * update_edgeport_E2PROM() Compare current versions of *
 * Boot ROM and Manufacture  *
 * Descriptors with versions *
 * embedded in this driver *
 * *
 ************************************************************************/
static void update_edgeport_E2PROM(struct edgeport_serial *edge_serial)
{
 struct device *dev = &edge_serial->serial->dev->dev;
 __u32 BootCurVer;
 __u32 BootNewVer;
 __u8 BootMajorVersion;
 __u8 BootMinorVersion;
 __u16 BootBuildNumber;
 __u32 Bootaddr;
 const struct ihex_binrec *rec;
 const struct firmware *fw;
 const char *fw_name;
 int response;

 switch (edge_serial->product_info.iDownloadFile) {
 case EDGE_DOWNLOAD_FILE_I930:
  fw_name = "edgeport/boot.fw";
  break;
 case EDGE_DOWNLOAD_FILE_80251:
  fw_name = "edgeport/boot2.fw";
  break;
 default:
  return;
 }

 response = request_ihex_firmware(&fw, fw_name,
      &edge_serial->serial->dev->dev);
 if (response) {
  dev_err(dev, "Failed to load image \"%s\" err %d\n",
         fw_name, response);
  return;
 }

 rec = (const struct ihex_binrec *)fw->data;
 BootMajorVersion = rec->data[0];
 BootMinorVersion = rec->data[1];
 BootBuildNumber = (rec->data[2] << 8) | rec->data[3];

 /* Check Boot Image Version */
 BootCurVer = (edge_serial->boot_descriptor.MajorVersion << 24) +
       (edge_serial->boot_descriptor.MinorVersion << 16) +
        le16_to_cpu(edge_serial->boot_descriptor.BuildNumber);

 BootNewVer = (BootMajorVersion << 24) +
       (BootMinorVersion << 16) +
        BootBuildNumber;

 dev_dbg(dev, "Current Boot Image version %d.%d.%d\n",
     edge_serial->boot_descriptor.MajorVersion,
     edge_serial->boot_descriptor.MinorVersion,
     le16_to_cpu(edge_serial->boot_descriptor.BuildNumber));


 if (BootNewVer > BootCurVer) {
  dev_dbg(dev, "**Update Boot Image from %d.%d.%d to %d.%d.%d\n",
      edge_serial->boot_descriptor.MajorVersion,
      edge_serial->boot_descriptor.MinorVersion,
      le16_to_cpu(edge_serial->boot_descriptor.BuildNumber),
      BootMajorVersion, BootMinorVersion, BootBuildNumber);

  dev_dbg(dev, "Downloading new Boot Image\n");

  for (rec = ihex_next_binrec(rec); rec;
       rec = ihex_next_binrec(rec)) {
   Bootaddr = be32_to_cpu(rec->addr);
   response = rom_write(edge_serial->serial,
          Bootaddr >> 16,
          Bootaddr & 0xFFFF,
          be16_to_cpu(rec->len),
          &rec->data[0]);
   if (response < 0) {
    dev_err(&edge_serial->serial->dev->dev,
     "rom_write failed (%x, %x, %d)\n",
     Bootaddr >> 16, Bootaddr & 0xFFFF,
     be16_to_cpu(rec->len));
    break;
   }
  }
 } else {
  dev_dbg(dev, "Boot Image -- already up to date\n");
 }
 release_firmware(fw);
}

static void dump_product_info(struct edgeport_serial *edge_serial,
         struct edgeport_product_info *product_info)
{
 struct device *dev = &edge_serial->serial->dev->dev;

 /* Dump Product Info structure */
 dev_dbg(dev, "**Product Information:\n");
 dev_dbg(dev, " ProductId %x\n", product_info->ProductId);
 dev_dbg(dev, " NumPorts %d\n", product_info->NumPorts);
 dev_dbg(dev, " ProdInfoVer %d\n", product_info->ProdInfoVer);
 dev_dbg(dev, " IsServer %d\n", product_info->IsServer);
 dev_dbg(dev, " IsRS232 %d\n", product_info->IsRS232);
 dev_dbg(dev, " IsRS422 %d\n", product_info->IsRS422);
 dev_dbg(dev, " IsRS485 %d\n", product_info->IsRS485);
 dev_dbg(dev, " RomSize %d\n", product_info->RomSize);
 dev_dbg(dev, " RamSize %d\n", product_info->RamSize);
 dev_dbg(dev, " CpuRev %x\n", product_info->CpuRev);
 dev_dbg(dev, " BoardRev %x\n", product_info->BoardRev);
 dev_dbg(dev, " BootMajorVersion %d.%d.%d\n",
  product_info->BootMajorVersion,
  product_info->BootMinorVersion,
  le16_to_cpu(product_info->BootBuildNumber));
 dev_dbg(dev, " FirmwareMajorVersion %d.%d.%d\n",
  product_info->FirmwareMajorVersion,
  product_info->FirmwareMinorVersion,
  le16_to_cpu(product_info->FirmwareBuildNumber));
 dev_dbg(dev, " ManufactureDescDate %d/%d/%d\n",
  product_info->ManufactureDescDate[0],
  product_info->ManufactureDescDate[1],
  product_info->ManufactureDescDate[2]+1900);
 dev_dbg(dev, " iDownloadFile 0x%x\n",
  product_info->iDownloadFile);
 dev_dbg(dev, " EpicVer %d\n", product_info->EpicVer);
}

static void get_product_info(struct edgeport_serial *edge_serial)
{
 struct edgeport_product_info *product_info = &edge_serial->product_info;

 memset(product_info, 0, sizeof(struct edgeport_product_info));

 product_info->ProductId = (__u16)(le16_to_cpu(edge_serial->serial->dev->descriptor.idProduct) & ~ION_DEVICE_ID_80251_NETCHIP);
 product_info->NumPorts = edge_serial->manuf_descriptor.NumPorts;
 product_info->ProdInfoVer = 0;

 product_info->RomSize = edge_serial->manuf_descriptor.RomSize;
 product_info->RamSize = edge_serial->manuf_descriptor.RamSize;
 product_info->CpuRev = edge_serial->manuf_descriptor.CpuRev;
 product_info->BoardRev = edge_serial->manuf_descriptor.BoardRev;

 product_info->BootMajorVersion =
    edge_serial->boot_descriptor.MajorVersion;
 product_info->BootMinorVersion =
    edge_serial->boot_descriptor.MinorVersion;
 product_info->BootBuildNumber =
    edge_serial->boot_descriptor.BuildNumber;

 memcpy(product_info->ManufactureDescDate,
   edge_serial->manuf_descriptor.DescDate,
   sizeof(edge_serial->manuf_descriptor.DescDate));

 /* check if this is 2nd generation hardware */
 if (le16_to_cpu(edge_serial->serial->dev->descriptor.idProduct)
         & ION_DEVICE_ID_80251_NETCHIP)
  product_info->iDownloadFile = EDGE_DOWNLOAD_FILE_80251;
 else
  product_info->iDownloadFile = EDGE_DOWNLOAD_FILE_I930;

 /* Determine Product type and set appropriate flags */
 switch (DEVICE_ID_FROM_USB_PRODUCT_ID(product_info->ProductId)) {
 case ION_DEVICE_ID_EDGEPORT_COMPATIBLE:
 case ION_DEVICE_ID_EDGEPORT_4T:
 case ION_DEVICE_ID_EDGEPORT_4:
 case ION_DEVICE_ID_EDGEPORT_2:
 case ION_DEVICE_ID_EDGEPORT_8_DUAL_CPU:
 case ION_DEVICE_ID_EDGEPORT_8:
 case ION_DEVICE_ID_EDGEPORT_421:
 case ION_DEVICE_ID_EDGEPORT_21:
 case ION_DEVICE_ID_EDGEPORT_2_DIN:
 case ION_DEVICE_ID_EDGEPORT_4_DIN:
 case ION_DEVICE_ID_EDGEPORT_16_DUAL_CPU:
  product_info->IsRS232 = 1;
  break;

 case ION_DEVICE_ID_EDGEPORT_2I: /* Edgeport/2 RS422/RS485 */
  product_info->IsRS422 = 1;
  product_info->IsRS485 = 1;
  break;

 case ION_DEVICE_ID_EDGEPORT_8I: /* Edgeport/4 RS422 */
 case ION_DEVICE_ID_EDGEPORT_4I: /* Edgeport/4 RS422 */
  product_info->IsRS422 = 1;
  break;
 }

 dump_product_info(edge_serial, product_info);
}

static int get_epic_descriptor(struct edgeport_serial *ep)
{
 int result;
 struct usb_serial *serial = ep->serial;
 struct edgeport_product_info *product_info = &ep->product_info;
 struct edge_compatibility_descriptor *epic;
 struct edge_compatibility_bits *bits;
 struct device *dev = &serial->dev->dev;

 ep->is_epic = 0;

 epic = kmalloc(sizeof(*epic), GFP_KERNEL);
 if (!epic)
  return -ENOMEM;

 result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
     USB_REQUEST_ION_GET_EPIC_DESC,
     0xC0, 0x00, 0x00,
     epic, sizeof(*epic),
     300);
 if (result == sizeof(*epic)) {
  ep->is_epic = 1;
  memcpy(&ep->epic_descriptor, epic, sizeof(*epic));
  memset(product_info, 0, sizeof(struct edgeport_product_info));

  product_info->NumPorts = epic->NumPorts;
  product_info->ProdInfoVer = 0;
  product_info->FirmwareMajorVersion = epic->MajorVersion;
  product_info->FirmwareMinorVersion = epic->MinorVersion;
  product_info->FirmwareBuildNumber = epic->BuildNumber;
  product_info->iDownloadFile = epic->iDownloadFile;
  product_info->EpicVer = epic->EpicVer;
  product_info->Epic = epic->Supports;
  product_info->ProductId = ION_DEVICE_ID_EDGEPORT_COMPATIBLE;
  dump_product_info(ep, product_info);

  bits = &ep->epic_descriptor.Supports;
  dev_dbg(dev, "**EPIC descriptor:\n");
  dev_dbg(dev, " VendEnableSuspend: %s\n", bits->VendEnableSuspend ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPOpen : %s\n", bits->IOSPOpen ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPClose : %s\n", bits->IOSPClose ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPChase : %s\n", bits->IOSPChase ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPSetRxFlow : %s\n", bits->IOSPSetRxFlow ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPSetTxFlow : %s\n", bits->IOSPSetTxFlow ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPSetXChar : %s\n", bits->IOSPSetXChar ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPRxCheck : %s\n", bits->IOSPRxCheck ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPSetClrBreak : %s\n", bits->IOSPSetClrBreak ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPWriteMCR : %s\n", bits->IOSPWriteMCR ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPWriteLCR : %s\n", bits->IOSPWriteLCR ? "TRUE": "FALSE");
  dev_dbg(dev, " IOSPSetBaudRate : %s\n", bits->IOSPSetBaudRate ? "TRUE": "FALSE");
  dev_dbg(dev, " TrueEdgeport : %s\n", bits->TrueEdgeport ? "TRUE": "FALSE");

  result = 0;
 } else if (result >= 0) {
  dev_warn(&serial->interface->dev, "short epic descriptor received: %d\n",
    result);
  result = -EIO;
 }

 kfree(epic);

 return result;
}


/************************************************************************/
/************************************************************************/
/*            U S B  C A L L B A C K   F U N C T I O N S                */
/*            U S B  C A L L B A C K   F U N C T I O N S                */
/************************************************************************/
/************************************************************************/

/*****************************************************************************
 * edge_interrupt_callback
 * this is the callback function for when we have received data on the
 * interrupt endpoint.
 *****************************************************************************/
static void edge_interrupt_callback(struct urb *urb)
{
 struct edgeport_serial *edge_serial = urb->context;
 struct device *dev;
 struct edgeport_port *edge_port;
 struct usb_serial_port *port;
 unsigned char *data = urb->transfer_buffer;
 int length = urb->actual_length;
 unsigned long flags;
 int bytes_avail;
 int position;
 int txCredits;
 int portNumber;
 int result;
 int status = urb->status;

 switch (status) {
 case 0:
  /* success */
  break;
 case -ECONNRESET:
 case -ENOENT:
 case -ESHUTDOWN:
  /* this urb is terminated, clean up */
  dev_dbg(&urb->dev->dev, "%s - urb shutting down with status: %d\n", __func__, status);
  return;
 default:
  dev_dbg(&urb->dev->dev, "%s - nonzero urb status received: %d\n", __func__, status);
  goto exit;
 }

 dev = &edge_serial->serial->dev->dev;

 /* process this interrupt-read even if there are no ports open */
 if (length) {
  usb_serial_debug_data(dev, __func__, length, data);

  if (length > 1) {
   bytes_avail = data[0] | (data[1] << 8);
   if (bytes_avail) {
    spin_lock_irqsave(&edge_serial->es_lock, flags);
    edge_serial->rxBytesAvail += bytes_avail;
    dev_dbg(dev,
     "%s - bytes_avail=%d, rxBytesAvail=%d, read_in_progress=%d\n",
     __func__, bytes_avail,
     edge_serial->rxBytesAvail,
     edge_serial->read_in_progress);

    if (edge_serial->rxBytesAvail > 0 &&
        !edge_serial->read_in_progress) {
     dev_dbg(dev, "%s - posting a read\n", __func__);
     edge_serial->read_in_progress = true;

     /* we have pending bytes on the
   bulk in pipe, send a request */
     result = usb_submit_urb(edge_serial->read_urb, GFP_ATOMIC);
     if (result) {
      dev_err(dev,
       "%s - usb_submit_urb(read bulk) failed with result = %d\n",
       __func__, result);
      edge_serial->read_in_progress = false;
     }
    }
    spin_unlock_irqrestore(&edge_serial->es_lock,
             flags);
   }
  }
  /* grab the txcredits for the ports if available */
  position = 2;
  portNumber = 0;
  while ((position < length - 1) &&
    (portNumber < edge_serial->serial->num_ports)) {
   txCredits = data[position] | (data[position+1] << 8);
   if (txCredits) {
    port = edge_serial->serial->port[portNumber];
    edge_port = usb_get_serial_port_data(port);
    if (edge_port && edge_port->open) {
     spin_lock_irqsave(&edge_port->ep_lock,
         flags);
     edge_port->txCredits += txCredits;
     spin_unlock_irqrestore(&edge_port->ep_lock,
              flags);
     dev_dbg(dev, "%s - txcredits for port%d = %d\n",
      __func__, portNumber,
      edge_port->txCredits);

     /* tell the tty driver that something
   has changed */
     tty_port_tty_wakeup(&edge_port->port->port);
     /* Since we have more credit, check
   if more data can be sent */
     send_more_port_data(edge_serial,
        edge_port);
    }
   }
   position += 2;
   ++portNumber;
  }
 }

exit:
 result = usb_submit_urb(urb, GFP_ATOMIC);
 if (result)
  dev_err(&urb->dev->dev,
   "%s - Error %d submitting control urb\n",
      __func__, result);
}


/*****************************************************************************
 * edge_bulk_in_callback
 * this is the callback function for when we have received data on the
 * bulk in endpoint.
 *****************************************************************************/
static void edge_bulk_in_callback(struct urb *urb)
{
 struct edgeport_serial *edge_serial = urb->context;
 struct device *dev;
 unsigned char  *data = urb->transfer_buffer;
 int   retval;
 __u16   raw_data_length;
 int status = urb->status;
 unsigned long flags;

 if (status) {
  dev_dbg(&urb->dev->dev, "%s - nonzero read bulk status received: %d\n",
   __func__, status);
  edge_serial->read_in_progress = false;
  return;
 }

 if (urb->actual_length == 0) {
  dev_dbg(&urb->dev->dev, "%s - read bulk callback with no data\n", __func__);
  edge_serial->read_in_progress = false;
  return;
 }

 dev = &edge_serial->serial->dev->dev;
 raw_data_length = urb->actual_length;

 usb_serial_debug_data(dev, __func__, raw_data_length, data);

 spin_lock_irqsave(&edge_serial->es_lock, flags);

 /* decrement our rxBytes available by the number that we just got */
 edge_serial->rxBytesAvail -= raw_data_length;

 dev_dbg(dev, "%s - Received = %d, rxBytesAvail %d\n", __func__,
  raw_data_length, edge_serial->rxBytesAvail);

 process_rcvd_data(edge_serial, data, urb->actual_length);

 /* check to see if there's any more data for us to read */
 if (edge_serial->rxBytesAvail > 0) {
  dev_dbg(dev, "%s - posting a read\n", __func__);
  retval = usb_submit_urb(edge_serial->read_urb, GFP_ATOMIC);
  if (retval) {
   dev_err(dev,
    "%s - usb_submit_urb(read bulk) failed, retval = %d\n",
    __func__, retval);
   edge_serial->read_in_progress = false;
  }
 } else {
  edge_serial->read_in_progress = false;
 }

 spin_unlock_irqrestore(&edge_serial->es_lock, flags);
}


/*****************************************************************************
 * edge_bulk_out_data_callback
 * this is the callback function for when we have finished sending
 * serial data on the bulk out endpoint.
 *****************************************************************************/
static void edge_bulk_out_data_callback(struct urb *urb)
{
 struct edgeport_port *edge_port = urb->context;
 int status = urb->status;

 if (status) {
  dev_dbg(&urb->dev->dev,
   "%s - nonzero write bulk status received: %d\n",
   __func__, status);
 }

 if (edge_port->open)
  tty_port_tty_wakeup(&edge_port->port->port);

 /* Release the Write URB */
 edge_port->write_in_progress = false;

 /* Check if more data needs to be sent */
 send_more_port_data((struct edgeport_serial *)
  (usb_get_serial_data(edge_port->port->serial)), edge_port);
}


/*****************************************************************************
 * BulkOutCmdCallback
 * this is the callback function for when we have finished sending a
 * command on the bulk out endpoint.
 *****************************************************************************/
static void edge_bulk_out_cmd_callback(struct urb *urb)
{
 struct edgeport_port *edge_port = urb->context;
 struct device *dev = &urb->dev->dev;
 int status = urb->status;

 atomic_dec(&CmdUrbs);
 dev_dbg(dev, "%s - FREE URB %p (outstanding %d)\n", __func__, urb,
  atomic_read(&CmdUrbs));


 /* clean up the transfer buffer */
 kfree(urb->transfer_buffer);

 /* Free the command urb */
 usb_free_urb(urb);

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

 /* tell the tty driver that something has changed */
 if (edge_port->open)
  tty_port_tty_wakeup(&edge_port->port->port);

 /* we have completed the command */
 edge_port->commandPending = false;
 wake_up(&edge_port->wait_command);
}


/*****************************************************************************
 * Driver tty interface functions
 *****************************************************************************/

/*****************************************************************************
 * SerialOpen
 * this function is called by the tty driver when a port is opened
 * If successful, we return 0
 * Otherwise we return a negative error number.
 *****************************************************************************/
static int edge_open(struct tty_struct *tty, struct usb_serial_port *port)
{
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 struct device *dev = &port->dev;
 struct usb_serial *serial;
 struct edgeport_serial *edge_serial;
 int response;

 if (edge_port == NULL)
  return -ENODEV;

 /* see if we've set up our endpoint info yet (can't set it up
   in edge_startup as the structures were not set up at that time.) */
 serial = port->serial;
 edge_serial = usb_get_serial_data(serial);
 if (edge_serial == NULL)
  return -ENODEV;
 if (edge_serial->interrupt_in_buffer == NULL) {
  struct usb_serial_port *port0 = serial->port[0];

  /* not set up yet, so do it now */
  edge_serial->interrupt_in_buffer =
     port0->interrupt_in_buffer;
  edge_serial->interrupt_in_endpoint =
     port0->interrupt_in_endpointAddress;
  edge_serial->interrupt_read_urb = port0->interrupt_in_urb;
  edge_serial->bulk_in_buffer = port0->bulk_in_buffer;
  edge_serial->bulk_in_endpoint =
     port0->bulk_in_endpointAddress;
  edge_serial->read_urb = port0->read_urb;
  edge_serial->bulk_out_endpoint =
     port0->bulk_out_endpointAddress;

  /* set up our interrupt urb */
  usb_fill_int_urb(edge_serial->interrupt_read_urb,
        serial->dev,
        usb_rcvintpipe(serial->dev,
    port0->interrupt_in_endpointAddress),
        port0->interrupt_in_buffer,
        edge_serial->interrupt_read_urb->transfer_buffer_length,
        edge_interrupt_callback, edge_serial,
        edge_serial->interrupt_read_urb->interval);

  /* set up our bulk in urb */
  usb_fill_bulk_urb(edge_serial->read_urb, serial->dev,
   usb_rcvbulkpipe(serial->dev,
    port0->bulk_in_endpointAddress),
   port0->bulk_in_buffer,
   edge_serial->read_urb->transfer_buffer_length,
   edge_bulk_in_callback, edge_serial);
  edge_serial->read_in_progress = false;

  /* start interrupt read for this edgeport
 * this interrupt will continue as long
 * as the edgeport is connected */
  response = usb_submit_urb(edge_serial->interrupt_read_urb,
        GFP_KERNEL);
  if (response) {
   dev_err(dev, "%s - Error %d submitting control urb\n",
    __func__, response);
  }
 }

 /* initialize our wait queues */
 init_waitqueue_head(&edge_port->wait_open);
 init_waitqueue_head(&edge_port->wait_chase);
 init_waitqueue_head(&edge_port->wait_command);

 /* initialize our port settings */
 edge_port->txCredits = 0; /* Can't send any data yet */
 /* Must always set this bit to enable ints! */
 edge_port->shadowMCR = MCR_MASTER_IE;
 edge_port->chaseResponsePending = false;

 /* send a open port command */
 edge_port->openPending = true;
 edge_port->open        = false;
 response = send_iosp_ext_cmd(edge_port, IOSP_CMD_OPEN_PORT, 0);

 if (response < 0) {
  dev_err(dev, "%s - error sending open port command\n", __func__);
  edge_port->openPending = false;
  return -ENODEV;
 }

 /* now wait for the port to be completely opened */
 wait_event_timeout(edge_port->wait_open, !edge_port->openPending,
        OPEN_TIMEOUT);

 if (!edge_port->open) {
  /* open timed out */
  dev_dbg(dev, "%s - open timeout\n", __func__);
  edge_port->openPending = false;
  return -ENODEV;
 }

 /* create the txfifo */
 edge_port->txfifo.head = 0;
 edge_port->txfifo.tail = 0;
 edge_port->txfifo.count = 0;
 edge_port->txfifo.size = edge_port->maxTxCredits;
 edge_port->txfifo.fifo = kmalloc(edge_port->maxTxCredits, GFP_KERNEL);

 if (!edge_port->txfifo.fifo) {
  edge_close(port);
  return -ENOMEM;
 }

 /* Allocate a URB for the write */
 edge_port->write_urb = usb_alloc_urb(0, GFP_KERNEL);
 edge_port->write_in_progress = false;

 if (!edge_port->write_urb) {
  edge_close(port);
  return -ENOMEM;
 }

 dev_dbg(dev, "%s - Initialize TX fifo to %d bytes\n",
  __func__, edge_port->maxTxCredits);

 return 0;
}


/************************************************************************
 *
 * block_until_chase_response
 *
 * This function will block the close until one of the following:
 * 1. Response to our Chase comes from Edgeport
 * 2. A timeout of 10 seconds without activity has expired
 *    (1K of Edgeport data @ 2400 baud ==> 4 sec to empty)
 *
 ************************************************************************/
static void block_until_chase_response(struct edgeport_port *edge_port)
{
 struct device *dev = &edge_port->port->dev;
 DEFINE_WAIT(wait);
 __u16 lastCredits;
 int timeout = 1*HZ;
 int loop = 10;

 while (1) {
  /* Save Last credits */
  lastCredits = edge_port->txCredits;

  /* Did we get our Chase response */
  if (!edge_port->chaseResponsePending) {
   dev_dbg(dev, "%s - Got Chase Response\n", __func__);

   /* did we get all of our credit back? */
   if (edge_port->txCredits == edge_port->maxTxCredits) {
    dev_dbg(dev, "%s - Got all credits\n", __func__);
    return;
   }
  }

  /* Block the thread for a while */
  prepare_to_wait(&edge_port->wait_chase, &wait,
      TASK_UNINTERRUPTIBLE);
  schedule_timeout(timeout);
  finish_wait(&edge_port->wait_chase, &wait);

  if (lastCredits == edge_port->txCredits) {
   /* No activity.. count down. */
   loop--;
   if (loop == 0) {
    edge_port->chaseResponsePending = false;
    dev_dbg(dev, "%s - Chase TIMEOUT\n", __func__);
    return;
   }
  } else {
   /* Reset timeout value back to 10 seconds */
   dev_dbg(dev, "%s - Last %d, Current %d\n", __func__,
     lastCredits, edge_port->txCredits);
   loop = 10;
  }
 }
}


/************************************************************************
 *
 * block_until_tx_empty
 *
 * This function will block the close until one of the following:
 * 1. TX count are 0
 * 2. The edgeport has stopped
 * 3. A timeout of 3 seconds without activity has expired
 *
 ************************************************************************/
static void block_until_tx_empty(struct edgeport_port *edge_port)
{
 struct device *dev = &edge_port->port->dev;
 DEFINE_WAIT(wait);
 struct TxFifo *fifo = &edge_port->txfifo;
 __u32 lastCount;
 int timeout = HZ/10;
 int loop = 30;

 while (1) {
  /* Save Last count */
  lastCount = fifo->count;

  /* Is the Edgeport Buffer empty? */
  if (lastCount == 0) {
   dev_dbg(dev, "%s - TX Buffer Empty\n", __func__);
   return;
  }

  /* Block the thread for a while */
  prepare_to_wait(&edge_port->wait_chase, &wait,
      TASK_UNINTERRUPTIBLE);
  schedule_timeout(timeout);
  finish_wait(&edge_port->wait_chase, &wait);

  dev_dbg(dev, "%s wait\n", __func__);

  if (lastCount == fifo->count) {
   /* No activity.. count down. */
   loop--;
   if (loop == 0) {
    dev_dbg(dev, "%s - TIMEOUT\n", __func__);
    return;
   }
  } else {
   /* Reset timeout value back to seconds */
   loop = 30;
  }
 }
}


/*****************************************************************************
 * edge_close
 * this function is called by the tty driver when a port is closed
 *****************************************************************************/
static void edge_close(struct usb_serial_port *port)
{
 struct edgeport_serial *edge_serial;
 struct edgeport_port *edge_port;
 int status;

 edge_serial = usb_get_serial_data(port->serial);
 edge_port = usb_get_serial_port_data(port);
 if (edge_serial == NULL || edge_port == NULL)
  return;

 /* block until tx is empty */
 block_until_tx_empty(edge_port);

 edge_port->closePending = true;

 if (!edge_serial->is_epic ||
     edge_serial->epic_descriptor.Supports.IOSPChase) {
  /* flush and chase */
  edge_port->chaseResponsePending = true;

  dev_dbg(&port->dev, "%s - Sending IOSP_CMD_CHASE_PORT\n", __func__);
  status = send_iosp_ext_cmd(edge_port, IOSP_CMD_CHASE_PORT, 0);
  if (status == 0)
   /* block until chase finished */
   block_until_chase_response(edge_port);
  else
   edge_port->chaseResponsePending = false;
 }

 if (!edge_serial->is_epic ||
     edge_serial->epic_descriptor.Supports.IOSPClose) {
        /* close the port */
  dev_dbg(&port->dev, "%s - Sending IOSP_CMD_CLOSE_PORT\n", __func__);
  send_iosp_ext_cmd(edge_port, IOSP_CMD_CLOSE_PORT, 0);
 }

 /* port->close = true; */
 edge_port->closePending = false;
 edge_port->open = false;
 edge_port->openPending = false;

 usb_kill_urb(edge_port->write_urb);

 if (edge_port->write_urb) {
  /* if this urb had a transfer buffer already
(old transfer) free it */
  kfree(edge_port->write_urb->transfer_buffer);
  usb_free_urb(edge_port->write_urb);
  edge_port->write_urb = NULL;
 }
 kfree(edge_port->txfifo.fifo);
 edge_port->txfifo.fifo = NULL;
}

/*****************************************************************************
 * SerialWrite
 * this function is called by the tty driver when data should be written
 * to the port.
 * If successful, we return the number of bytes written, otherwise we
 * return a negative error number.
 *****************************************************************************/
static int edge_write(struct tty_struct *tty, struct usb_serial_port *port,
     const unsigned char *data, int count)
{
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 struct TxFifo *fifo;
 int copySize;
 int bytesleft;
 int firsthalf;
 int secondhalf;
 unsigned long flags;

 if (edge_port == NULL)
  return -ENODEV;

 /* get a pointer to the Tx fifo */
 fifo = &edge_port->txfifo;

 spin_lock_irqsave(&edge_port->ep_lock, flags);

 /* calculate number of bytes to put in fifo */
 copySize = min_t(unsigned int, count,
    (edge_port->txCredits - fifo->count));

 dev_dbg(&port->dev, "%s of %d byte(s) Fifo room %d -- will copy %d bytes\n",
  __func__, count, edge_port->txCredits - fifo->count, copySize);

 /* catch writes of 0 bytes which the tty driver likes to give us,
   and when txCredits is empty */
 if (copySize == 0) {
  dev_dbg(&port->dev, "%s - copySize = Zero\n", __func__);
  goto finish_write;
 }

 /* queue the data
 * since we can never overflow the buffer we do not have to check for a
 * full condition
 *
 * the copy is done is two parts -- first fill to the end of the buffer
 * then copy the reset from the start of the buffer
 */
 bytesleft = fifo->size - fifo->head;
 firsthalf = min(bytesleft, copySize);
 dev_dbg(&port->dev, "%s - copy %d bytes of %d into fifo \n", __func__,
  firsthalf, bytesleft);

 /* now copy our data */
 memcpy(&fifo->fifo[fifo->head], data, firsthalf);
 usb_serial_debug_data(&port->dev, __func__, firsthalf, &fifo->fifo[fifo->head]);

 /* update the index and size */
 fifo->head  += firsthalf;
 fifo->count += firsthalf;

 /* wrap the index */
 if (fifo->head == fifo->size)
  fifo->head = 0;

 secondhalf = copySize-firsthalf;

 if (secondhalf) {
  dev_dbg(&port->dev, "%s - copy rest of data %d\n", __func__, secondhalf);
  memcpy(&fifo->fifo[fifo->head], &data[firsthalf], secondhalf);
  usb_serial_debug_data(&port->dev, __func__, secondhalf, &fifo->fifo[fifo->head]);
  /* update the index and size */
  fifo->count += secondhalf;
  fifo->head  += secondhalf;
  /* No need to check for wrap since we can not get to end of
 * the fifo in this part
 */
 }

finish_write:
 spin_unlock_irqrestore(&edge_port->ep_lock, flags);

 send_more_port_data((struct edgeport_serial *)
   usb_get_serial_data(port->serial), edge_port);

 dev_dbg(&port->dev, "%s wrote %d byte(s) TxCredits %d, Fifo %d\n",
  __func__, copySize, edge_port->txCredits, fifo->count);

 return copySize;
}


/************************************************************************
 *
 * send_more_port_data()
 *
 * This routine attempts to write additional UART transmit data
 * to a port over the USB bulk pipe. It is called (1) when new
 * data has been written to a port's TxBuffer from higher layers
 * (2) when the peripheral sends us additional TxCredits indicating
 * that it can accept more Tx data for a given port; and (3) when
 * a bulk write completes successfully and we want to see if we
 * can transmit more.
 *
 ************************************************************************/
static void send_more_port_data(struct edgeport_serial *edge_serial,
     struct edgeport_port *edge_port)
{
 struct TxFifo *fifo = &edge_port->txfifo;
 struct device *dev = &edge_port->port->dev;
 struct urb *urb;
 unsigned char *buffer;
 int  status;
 int  count;
 int  bytesleft;
 int  firsthalf;
 int  secondhalf;
 unsigned long flags;

 spin_lock_irqsave(&edge_port->ep_lock, flags);

 if (edge_port->write_in_progress ||
     !edge_port->open             ||
     (fifo->count == 0)) {
  dev_dbg(dev, "%s EXIT - fifo %d, PendingWrite = %d\n",
   __func__, fifo->count, edge_port->write_in_progress);
  goto exit_send;
 }

 /* since the amount of data in the fifo will always fit into the
 * edgeport buffer we do not need to check the write length
 *
 * Do we have enough credits for this port to make it worthwhile
 * to bother queueing a write. If it's too small, say a few bytes,
 * it's better to wait for more credits so we can do a larger write.
 */
 if (edge_port->txCredits < EDGE_FW_GET_TX_CREDITS_SEND_THRESHOLD(edge_port->maxTxCredits, EDGE_FW_BULK_MAX_PACKET_SIZE)) {
  dev_dbg(dev, "%s Not enough credit - fifo %d TxCredit %d\n",
   __func__, fifo->count, edge_port->txCredits);
  goto exit_send;
 }

 /* lock this write */
 edge_port->write_in_progress = true;

 /* get a pointer to the write_urb */
 urb = edge_port->write_urb;

 /* make sure transfer buffer is freed */
 kfree(urb->transfer_buffer);
 urb->transfer_buffer = NULL;

 /* build the data header for the buffer and port that we are about
   to send out */
 count = fifo->count;
 buffer = kmalloc(count+2, GFP_ATOMIC);
 if (!buffer) {
  edge_port->write_in_progress = false;
  goto exit_send;
 }
 buffer[0] = IOSP_BUILD_DATA_HDR1(edge_port->port->port_number, count);
 buffer[1] = IOSP_BUILD_DATA_HDR2(edge_port->port->port_number, count);

 /* now copy our data */
 bytesleft =  fifo->size - fifo->tail;
 firsthalf = min(bytesleft, count);
 memcpy(&buffer[2], &fifo->fifo[fifo->tail], firsthalf);
 fifo->tail  += firsthalf;
 fifo->count -= firsthalf;
 if (fifo->tail == fifo->size)
  fifo->tail = 0;

 secondhalf = count-firsthalf;
 if (secondhalf) {
  memcpy(&buffer[2+firsthalf], &fifo->fifo[fifo->tail],
        secondhalf);
  fifo->tail  += secondhalf;
  fifo->count -= secondhalf;
 }

 if (count)
  usb_serial_debug_data(&edge_port->port->dev, __func__, count, &buffer[2]);

 /* fill up the urb with all of our data and submit it */
 usb_fill_bulk_urb(urb, edge_serial->serial->dev,
   usb_sndbulkpipe(edge_serial->serial->dev,
     edge_serial->bulk_out_endpoint),
   buffer, count+2,
   edge_bulk_out_data_callback, edge_port);

 /* decrement the number of credits we have by the number we just sent */
 edge_port->txCredits -= count;
 edge_port->port->icount.tx += count;

 status = usb_submit_urb(urb, GFP_ATOMIC);
 if (status) {
  /* something went wrong */
  dev_err_console(edge_port->port,
   "%s - usb_submit_urb(write bulk) failed, status = %d, data lost\n",
    __func__, status);
  edge_port->write_in_progress = false;

  /* revert the credits as something bad happened. */
  edge_port->txCredits += count;
  edge_port->port->icount.tx -= count;
 }
 dev_dbg(dev, "%s wrote %d byte(s) TxCredit %d, Fifo %d\n",
  __func__, count, edge_port->txCredits, fifo->count);

exit_send:
 spin_unlock_irqrestore(&edge_port->ep_lock, flags);
}


/*****************************************************************************
 * edge_write_room
 * this function is called by the tty driver when it wants to know how
 * many bytes of data we can accept for a specific port.
 *****************************************************************************/
static unsigned int edge_write_room(struct tty_struct *tty)
{
 struct usb_serial_port *port = tty->driver_data;
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 unsigned int room;
 unsigned long flags;

 /* total of both buffers is still txCredit */
 spin_lock_irqsave(&edge_port->ep_lock, flags);
 room = edge_port->txCredits - edge_port->txfifo.count;
 spin_unlock_irqrestore(&edge_port->ep_lock, flags);

 dev_dbg(&port->dev, "%s - returns %u\n", __func__, room);
 return room;
}


/*****************************************************************************
 * edge_chars_in_buffer
 * this function is called by the tty driver when it wants to know how
 * many bytes of data we currently have outstanding in the port (data that
 * has been written, but hasn't made it out the port yet)
 *****************************************************************************/
static unsigned int edge_chars_in_buffer(struct tty_struct *tty)
{
 struct usb_serial_port *port = tty->driver_data;
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 unsigned int num_chars;
 unsigned long flags;

 spin_lock_irqsave(&edge_port->ep_lock, flags);
 num_chars = edge_port->maxTxCredits - edge_port->txCredits +
      edge_port->txfifo.count;
 spin_unlock_irqrestore(&edge_port->ep_lock, flags);
 if (num_chars) {
  dev_dbg(&port->dev, "%s - returns %u\n", __func__, num_chars);
 }

 return num_chars;
}


/*****************************************************************************
 * SerialThrottle
 * this function is called by the tty driver when it wants to stop the data
 * being read from the port.
 *****************************************************************************/
static void edge_throttle(struct tty_struct *tty)
{
 struct usb_serial_port *port = tty->driver_data;
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 int status;

 if (edge_port == NULL)
  return;

 if (!edge_port->open) {
  dev_dbg(&port->dev, "%s - port not opened\n", __func__);
  return;
 }

 /* if we are implementing XON/XOFF, send the stop character */
 if (I_IXOFF(tty)) {
  unsigned char stop_char = STOP_CHAR(tty);
  status = edge_write(tty, port, &stop_char, 1);
  if (status <= 0)
   return;
 }

 /* if we are implementing RTS/CTS, toggle that line */
 if (C_CRTSCTS(tty)) {
  edge_port->shadowMCR &= ~MCR_RTS;
  status = send_cmd_write_uart_register(edge_port, MCR,
       edge_port->shadowMCR);
  if (status != 0)
   return;
 }
}


/*****************************************************************************
 * edge_unthrottle
 * this function is called by the tty driver when it wants to resume the
 * data being read from the port (called after SerialThrottle is called)
 *****************************************************************************/
static void edge_unthrottle(struct tty_struct *tty)
{
 struct usb_serial_port *port = tty->driver_data;
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 int status;

 if (edge_port == NULL)
  return;

 if (!edge_port->open) {
  dev_dbg(&port->dev, "%s - port not opened\n", __func__);
  return;
 }

 /* if we are implementing XON/XOFF, send the start character */
 if (I_IXOFF(tty)) {
  unsigned char start_char = START_CHAR(tty);
  status = edge_write(tty, port, &start_char, 1);
  if (status <= 0)
   return;
 }
 /* if we are implementing RTS/CTS, toggle that line */
 if (C_CRTSCTS(tty)) {
  edge_port->shadowMCR |= MCR_RTS;
  send_cmd_write_uart_register(edge_port, MCR,
      edge_port->shadowMCR);
 }
}


/*****************************************************************************
 * SerialSetTermios
 * this function is called by the tty driver when it wants to change
 * the termios structure
 *****************************************************************************/
static void edge_set_termios(struct tty_struct *tty,
        struct usb_serial_port *port,
        const struct ktermios *old_termios)
{
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);

 if (edge_port == NULL)
  return;

 if (!edge_port->open) {
  dev_dbg(&port->dev, "%s - port not opened\n", __func__);
  return;
 }

 /* change the port settings to the new ones specified */
 change_port_settings(tty, edge_port, old_termios);
}


/*****************************************************************************
 * get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 *      is emptied.  On bus types like RS485, the transmitter must
 *      release the bus after transmitting. This must be done when
 *      the transmit shift register is empty, not be done when the
 *      transmit holding register is empty.  This functionality
 *      allows an RS485 driver to be written in user space.
 *****************************************************************************/
static int get_lsr_info(struct edgeport_port *edge_port,
      unsigned int __user *value)
{
 unsigned int result = 0;
 unsigned long flags;

 spin_lock_irqsave(&edge_port->ep_lock, flags);
 if (edge_port->maxTxCredits == edge_port->txCredits &&
     edge_port->txfifo.count == 0) {
  dev_dbg(&edge_port->port->dev, "%s -- Empty\n", __func__);
  result = TIOCSER_TEMT;
 }
 spin_unlock_irqrestore(&edge_port->ep_lock, flags);

 if (copy_to_user(value, &result, sizeof(int)))
  return -EFAULT;
 return 0;
}

static int edge_tiocmset(struct tty_struct *tty,
     unsigned int set, unsigned int clear)
{
 struct usb_serial_port *port = tty->driver_data;
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 unsigned int mcr;

 mcr = edge_port->shadowMCR;
 if (set & TIOCM_RTS)
  mcr |= MCR_RTS;
 if (set & TIOCM_DTR)
  mcr |= MCR_DTR;
 if (set & TIOCM_LOOP)
  mcr |= MCR_LOOPBACK;

 if (clear & TIOCM_RTS)
  mcr &= ~MCR_RTS;
 if (clear & TIOCM_DTR)
  mcr &= ~MCR_DTR;
 if (clear & TIOCM_LOOP)
  mcr &= ~MCR_LOOPBACK;

 edge_port->shadowMCR = mcr;

 send_cmd_write_uart_register(edge_port, MCR, edge_port->shadowMCR);

 return 0;
}

static int edge_tiocmget(struct tty_struct *tty)
{
 struct usb_serial_port *port = tty->driver_data;
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 unsigned int result = 0;
 unsigned int msr;
 unsigned int mcr;

 msr = edge_port->shadowMSR;
 mcr = edge_port->shadowMCR;
 result = ((mcr & MCR_DTR) ? TIOCM_DTR: 0)   /* 0x002 */
    | ((mcr & MCR_RTS) ? TIOCM_RTS: 0)   /* 0x004 */
    | ((msr & EDGEPORT_MSR_CTS) ? TIOCM_CTS: 0)   /* 0x020 */
    | ((msr & EDGEPORT_MSR_CD) ? TIOCM_CAR: 0)   /* 0x040 */
    | ((msr & EDGEPORT_MSR_RI) ? TIOCM_RI:  0)   /* 0x080 */
    | ((msr & EDGEPORT_MSR_DSR) ? TIOCM_DSR: 0);  /* 0x100 */

 return result;
}

/*****************************************************************************
 * SerialIoctl
 * this function handles any ioctl calls to the driver
 *****************************************************************************/
static int edge_ioctl(struct tty_struct *tty,
     unsigned int cmd, unsigned long arg)
{
 struct usb_serial_port *port = tty->driver_data;
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);

 switch (cmd) {
 case TIOCSERGETLSR:
  dev_dbg(&port->dev, "%s TIOCSERGETLSR\n", __func__);
  return get_lsr_info(edge_port, (unsigned int __user *) arg);
 }
 return -ENOIOCTLCMD;
}


/*****************************************************************************
 * SerialBreak
 * this function sends a break to the port
 *****************************************************************************/
static int edge_break(struct tty_struct *tty, int break_state)
{
 struct usb_serial_port *port = tty->driver_data;
 struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 struct edgeport_serial *edge_serial = usb_get_serial_data(port->serial);
 int status = 0;

 if (!edge_serial->is_epic ||
     edge_serial->epic_descriptor.Supports.IOSPChase) {
  /* flush and chase */
  edge_port->chaseResponsePending = true;

  dev_dbg(&port->dev, "%s - Sending IOSP_CMD_CHASE_PORT\n", __func__);
  status = send_iosp_ext_cmd(edge_port, IOSP_CMD_CHASE_PORT, 0);
  if (status == 0) {
   /* block until chase finished */
   block_until_chase_response(edge_port);
  } else {
   edge_port->chaseResponsePending = false;
  }
 }

 if (!edge_serial->is_epic ||
     edge_serial->epic_descriptor.Supports.IOSPSetClrBreak) {
  if (break_state == -1) {
   dev_dbg(&port->dev, "%s - Sending IOSP_CMD_SET_BREAK\n", __func__);
   status = send_iosp_ext_cmd(edge_port,
      IOSP_CMD_SET_BREAK, 0);
  } else {
   dev_dbg(&port->dev, "%s - Sending IOSP_CMD_CLEAR_BREAK\n", __func__);
   status = send_iosp_ext_cmd(edge_port,
      IOSP_CMD_CLEAR_BREAK, 0);
  }
  if (status)
   dev_dbg(&port->dev, "%s - error sending break set/clear command.\n",
    __func__);
 }

 return status;
}


/*****************************************************************************
 * process_rcvd_data
 * this function handles the data received on the bulk in pipe.
 *****************************************************************************/
static void process_rcvd_data(struct edgeport_serial *edge_serial,
    unsigned char *buffer, __u16 bufferLength)
{
 struct usb_serial *serial = edge_serial->serial;
 struct device *dev = &serial->dev->dev;
 struct usb_serial_port *port;
 struct edgeport_port *edge_port;
 __u16 lastBufferLength;
 __u16 rxLen;

 lastBufferLength = bufferLength + 1;

 while (bufferLength > 0) {
  /* failsafe incase we get a message that we don't understand */
  if (lastBufferLength == bufferLength) {
   dev_dbg(dev, "%s - stuck in loop, exiting it.\n", __func__);
   break;
  }
  lastBufferLength = bufferLength;

  switch (edge_serial->rxState) {
  case EXPECT_HDR1:
   edge_serial->rxHeader1 = *buffer;
   ++buffer;
   --bufferLength;

   if (bufferLength == 0) {
    edge_serial->rxState = EXPECT_HDR2;
    break;
   }
   fallthrough;
  case EXPECT_HDR2:
   edge_serial->rxHeader2 = *buffer;
   ++buffer;
   --bufferLength;

   dev_dbg(dev, "%s - Hdr1=%02X Hdr2=%02X\n", __func__,
    edge_serial->rxHeader1, edge_serial->rxHeader2);
   /* Process depending on whether this header is
 * data or status */

   if (IS_CMD_STAT_HDR(edge_serial->rxHeader1)) {
    /* Decode this status header and go to
 * EXPECT_HDR1 (if we can process the status
 * with only 2 bytes), or go to EXPECT_HDR3 to
 * get the third byte. */
    edge_serial->rxPort =
        IOSP_GET_HDR_PORT(edge_serial->rxHeader1);
    edge_serial->rxStatusCode =
        IOSP_GET_STATUS_CODE(
      edge_serial->rxHeader1);

    if (!IOSP_STATUS_IS_2BYTE(
      edge_serial->rxStatusCode)) {
     /* This status needs additional bytes.
 * Save what we have and then wait for
 * more data.
 */
     edge_serial->rxStatusParam
      = edge_serial->rxHeader2;
     edge_serial->rxState = EXPECT_HDR3;
     break;
    }
    /* We have all the header bytes, process the
   status now */
    process_rcvd_status(edge_serial,
      edge_serial->rxHeader2, 0);
    edge_serial->rxState = EXPECT_HDR1;
    break;
   }

   edge_serial->rxPort = IOSP_GET_HDR_PORT(edge_serial->rxHeader1);
   edge_serial->rxBytesRemaining = IOSP_GET_HDR_DATA_LEN(edge_serial->rxHeader1,
               edge_serial->rxHeader2);
   dev_dbg(dev, "%s - Data for Port %u Len %u\n", __func__,
    edge_serial->rxPort,
    edge_serial->rxBytesRemaining);

   if (bufferLength == 0) {
    edge_serial->rxState = EXPECT_DATA;
    break;
   }
   fallthrough;
  case EXPECT_DATA: /* Expect data */
   if (bufferLength < edge_serial->rxBytesRemaining) {
    rxLen = bufferLength;
    /* Expect data to start next buffer */
    edge_serial->rxState = EXPECT_DATA;
   } else {
    /* BufLen >= RxBytesRemaining */
    rxLen = edge_serial->rxBytesRemaining;
    /* Start another header next time */
    edge_serial->rxState = EXPECT_HDR1;
   }

   bufferLength -= rxLen;
   edge_serial->rxBytesRemaining -= rxLen;

   /* spit this data back into the tty driver if this
   port is open */
   if (rxLen && edge_serial->rxPort < serial->num_ports) {
    port = serial->port[edge_serial->rxPort];
    edge_port = usb_get_serial_port_data(port);
    if (edge_port && edge_port->open) {
     dev_dbg(dev, "%s - Sending %d bytes to TTY for port %d\n",
      __func__, rxLen,
      edge_serial->rxPort);
     edge_tty_recv(edge_port->port, buffer,
       rxLen);
     edge_port->port->icount.rx += rxLen;
    }
   }
   buffer += rxLen;
   break;

  case EXPECT_HDR3: /* Expect 3rd byte of status header */
   edge_serial->rxHeader3 = *buffer;
   ++buffer;
   --bufferLength;

   /* We have all the header bytes, process the
   status now */
   process_rcvd_status(edge_serial,
    edge_serial->rxStatusParam,
    edge_serial->rxHeader3);
   edge_serial->rxState = EXPECT_HDR1;
   break;
  }
 }
}


/*****************************************************************************
 * process_rcvd_status
 * this function handles the any status messages received on the
 * bulk in pipe.
 *****************************************************************************/
static void process_rcvd_status(struct edgeport_serial *edge_serial,
      __u8 byte2, __u8 byte3)
{
 struct usb_serial_port *port;
 struct edgeport_port *edge_port;
 struct tty_struct *tty;
 struct device *dev;
 __u8 code = edge_serial->rxStatusCode;

 /* switch the port pointer to the one being currently talked about */
 if (edge_serial->rxPort >= edge_serial->serial->num_ports)
  return;
 port = edge_serial->serial->port[edge_serial->rxPort];
 edge_port = usb_get_serial_port_data(port);
 if (edge_port == NULL) {
  dev_err(&edge_serial->serial->dev->dev,
   "%s - edge_port == NULL for port %d\n",
     __func__, edge_serial->rxPort);
  return;
 }
 dev = &port->dev;

 if (code == IOSP_EXT_STATUS) {
  switch (byte2) {
  case IOSP_EXT_STATUS_CHASE_RSP:
   /* we want to do EXT status regardless of port
 * open/closed */
   dev_dbg(dev, "%s - Port %u EXT CHASE_RSP Data = %02x\n",
    __func__, edge_serial->rxPort, byte3);
   /* Currently, the only EXT_STATUS is Chase, so process
 * here instead of one more call to one more subroutine
 * If/when more EXT_STATUS, there'll be more work to do
 * Also, we currently clear flag and close the port
 * regardless of content of above's Byte3.
 * We could choose to do something else when Byte3 says
 * Timeout on Chase from Edgeport, like wait longer in
 * block_until_chase_response, but for now we don't.
 */
   edge_port->chaseResponsePending = false;
   wake_up(&edge_port->wait_chase);
   return;

  case IOSP_EXT_STATUS_RX_CHECK_RSP:
   dev_dbg(dev, "%s ========== Port %u CHECK_RSP Sequence = %02x =============\n",
    __func__, edge_serial->rxPort, byte3);
   /* Port->RxCheckRsp = true; */
   return;
  }
 }

 if (code == IOSP_STATUS_OPEN_RSP) {
  edge_port->txCredits = GET_TX_BUFFER_SIZE(byte3);
  edge_port->maxTxCredits = edge_port->txCredits;
  dev_dbg(dev, "%s - Port %u Open Response Initial MSR = %02x TxBufferSize = %d\n",
   __func__, edge_serial->rxPort, byte2, edge_port->txCredits);
  handle_new_msr(edge_port, byte2);

  /* send the current line settings to the port so we are
   in sync with any further termios calls */
  tty = tty_port_tty_get(&edge_port->port->port);
  if (tty) {
   change_port_settings(tty,
    edge_port, &tty->termios);
   tty_kref_put(tty);
  }

  /* we have completed the open */
  edge_port->openPending = false;
  edge_port->open = true;
  wake_up(&edge_port->wait_open);
  return;
 }

 /* If port is closed, silently discard all rcvd status. We can
 * have cases where buffered status is received AFTER the close
 * port command is sent to the Edgeport.
 */
 if (!edge_port->open || edge_port->closePending)
  return;

 switch (code) {
 /* Not currently sent by Edgeport */
 case IOSP_STATUS_LSR:
  dev_dbg(dev, "%s - Port %u LSR Status = %02x\n",
   __func__, edge_serial->rxPort, byte2);
  handle_new_lsr(edge_port, false, byte2, 0);
  break;

 case IOSP_STATUS_LSR_DATA:
  dev_dbg(dev, "%s - Port %u LSR Status = %02x, Data = %02x\n",
   __func__, edge_serial->rxPort, byte2, byte3);
  /* byte2 is LSR Register */
  /* byte3 is broken data byte */
  handle_new_lsr(edge_port, true, byte2, byte3);
  break;
 /*
 * case IOSP_EXT_4_STATUS:
 * dev_dbg(dev, "%s - Port %u LSR Status = %02x Data = %02x\n",
 * __func__, edge_serial->rxPort, byte2, byte3);
 * break;
 */
 case IOSP_STATUS_MSR:
  dev_dbg(dev, "%s - Port %u MSR Status = %02x\n",
   __func__, edge_serial->rxPort, byte2);
  /*
 * Process this new modem status and generate appropriate
 * events, etc, based on the new status. This routine
 * also saves the MSR in Port->ShadowMsr.
 */
  handle_new_msr(edge_port, byte2);
  break;

 default:
  dev_dbg(dev, "%s - Unrecognized IOSP status code %u\n", __func__, code);
  break;
 }
}


/*****************************************************************************
 * edge_tty_recv
 * this function passes data on to the tty flip buffer
 *****************************************************************************/
static void edge_tty_recv(struct usb_serial_port *port, unsigned char *data,
  int length)
{
 int cnt;

 cnt = tty_insert_flip_string(&port->port, data, length);
 if (cnt < length) {
  dev_err(&port->dev, "%s - dropping data, %d bytes lost\n",
    __func__, length - cnt);
 }
 data += cnt;
 length -= cnt;

 tty_flip_buffer_push(&port->port);
}


/*****************************************************************************
 * handle_new_msr
 * this function handles any change to the msr register for a port.
 *****************************************************************************/
static void handle_new_msr(struct edgeport_port *edge_port, __u8 newMsr)
{
 struct  async_icount *icount;

 if (newMsr & (EDGEPORT_MSR_DELTA_CTS | EDGEPORT_MSR_DELTA_DSR |
   EDGEPORT_MSR_DELTA_RI | EDGEPORT_MSR_DELTA_CD)) {
  icount = &edge_port->port->icount;

  /* update input line counters */
  if (newMsr & EDGEPORT_MSR_DELTA_CTS)
   icount->cts++;
  if (newMsr & EDGEPORT_MSR_DELTA_DSR)
   icount->dsr++;
  if (newMsr & EDGEPORT_MSR_DELTA_CD)
   icount->dcd++;
  if (newMsr & EDGEPORT_MSR_DELTA_RI)
   icount->rng++;
  wake_up_interruptible(&edge_port->port->port.delta_msr_wait);
 }

 /* Save the new modem status */
 edge_port->shadowMSR = newMsr & 0xf0;
}


/*****************************************************************************
 * handle_new_lsr
 * this function handles any change to the lsr register for a port.
 *****************************************************************************/
static void handle_new_lsr(struct edgeport_port *edge_port, __u8 lsrData,
       __u8 lsr, __u8 data)
{
 __u8 newLsr = (__u8) (lsr & (__u8)
  (LSR_OVER_ERR | LSR_PAR_ERR | LSR_FRM_ERR | LSR_BREAK));
 struct async_icount *icount;

 edge_port->shadowLSR = lsr;

 if (newLsr & LSR_BREAK) {
  /*
 * Parity and Framing errors only count if they
 * occur exclusive of a break being
 * received.
 */
  newLsr &= (__u8)(LSR_OVER_ERR | LSR_BREAK);
 }

 /* Place LSR data byte into Rx buffer */
 if (lsrData)
  edge_tty_recv(edge_port->port, &data, 1);

 /* update input line counters */
 icount = &edge_port->port->icount;
 if (newLsr & LSR_BREAK)
  icount->brk++;
 if (newLsr & LSR_OVER_ERR)
  icount->overrun++;
 if (newLsr & LSR_PAR_ERR)
  icount->parity++;
 if (newLsr & LSR_FRM_ERR)
  icount->frame++;
}


/****************************************************************************
 * sram_write
 * writes a number of bytes to the Edgeport device's sram starting at the
 * given address.
 * If successful returns the number of bytes written, otherwise it returns
 * a negative error number of the problem.
 ****************************************************************************/
static int sram_write(struct usb_serial *serial, __u16 extAddr, __u16 addr,
     __u16 length, const __u8 *data)
{
 int result;
 __u16 current_length;
 unsigned char *transfer_buffer;

 dev_dbg(&serial->dev->dev, "%s - %x, %x, %d\n", __func__, extAddr, addr, length);

 transfer_buffer =  kmalloc(64, GFP_KERNEL);
 if (!transfer_buffer)
  return -ENOMEM;

 /* need to split these writes up into 64 byte chunks */
 result = 0;
 while (length > 0) {
  if (length > 64)
   current_length = 64;
  else
   current_length = length;

/* dev_dbg(&serial->dev->dev, "%s - writing %x, %x, %d\n", __func__, extAddr, addr, current_length); */
  memcpy(transfer_buffer, data, current_length);
  result = usb_control_msg(serial->dev,
     usb_sndctrlpipe(serial->dev, 0),
     USB_REQUEST_ION_WRITE_RAM,
     0x40, addr, extAddr, transfer_buffer,
     current_length, 300);
  if (result < 0)
   break;
  length -= current_length;
  addr += current_length;
  data += current_length;
 }

 kfree(transfer_buffer);
 return result;
}


/****************************************************************************
 * rom_write
 * writes a number of bytes to the Edgeport device's ROM starting at the
 * given address.
--> --------------------

--> maximum size reached

--> --------------------