root/drivers/gpib/ni_usb/ni_usb_gpib.c
// SPDX-License-Identifier: GPL-2.0

/***************************************************************************
 * driver for National Instruments usb to gpib adapters
 *    copyright            : (C) 2004 by Frank Mori Hess
 ***************************************************************************/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#define dev_fmt pr_fmt
#define DRV_NAME KBUILD_MODNAME

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include "ni_usb_gpib.h"
#include "gpibP.h"
#include "nec7210.h"
#include "tnt4882_registers.h"

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("GPIB driver for National Instruments USB devices");

#define MAX_NUM_NI_USB_INTERFACES 128
static struct usb_interface *ni_usb_driver_interfaces[MAX_NUM_NI_USB_INTERFACES];

static int ni_usb_parse_status_block(const u8 *buffer, struct ni_usb_status_block *status);
static int ni_usb_set_interrupt_monitor(struct gpib_board *board, unsigned int monitored_bits);
static void ni_usb_stop(struct ni_usb_priv *ni_priv);

static DEFINE_MUTEX(ni_usb_hotplug_lock);

// calculates a reasonable timeout in that can be passed to usb functions
static inline unsigned long ni_usb_timeout_msecs(unsigned int usec)
{
        if (usec == 0)
                return 0;
        return 2000 + usec / 500;
};

// returns timeout code byte for use in ni-usb-b instructions
static unsigned short ni_usb_timeout_code(unsigned int usec)
{
        if (usec == 0)
                return 0xf0;
        else if (usec <= 10)
                return 0xf1;
        else if (usec <= 30)
                return 0xf2;
        else if (usec <= 100)
                return 0xf3;
        else if (usec <= 300)
                return 0xf4;
        else if (usec <= 1000)
                return 0xf5;
        else if (usec <= 3000)
                return 0xf6;
        else if (usec <= 10000)
                return 0xf7;
        else if (usec <= 30000)
                return 0xf8;
        else if (usec <= 100000)
                return 0xf9;
        else if (usec <= 300000)
                return 0xfa;
        else if (usec <= 1000000)
                return 0xfb;
        else if (usec <= 3000000)
                return 0xfc;
        else if (usec <= 10000000)
                return 0xfd;
        else if (usec <= 30000000)
                return 0xfe;
        else if (usec <= 100000000)
                return 0xff;
        else if  (usec <= 300000000)
                return 0x01;
        /*
         * NI driver actually uses 0xff for timeout T1000s, which is a bug in their code.
         * I've verified on a usb-b that a code of 0x2 is correct for a 1000 sec timeout
         */
        else if (usec <= 1000000000)
                return 0x02;
        pr_err("bug? usec is greater than 1e9\n");
        return 0xf0;
}

static void ni_usb_bulk_complete(struct urb *urb)
{
        struct ni_usb_urb_ctx *context = urb->context;

        complete(&context->complete);
}

static void ni_usb_timeout_handler(struct timer_list *t)
{
        struct ni_usb_priv *ni_priv = timer_container_of(ni_priv, t,
                                                         bulk_timer);
        struct ni_usb_urb_ctx *context = &ni_priv->context;

        context->timed_out = 1;
        complete(&context->complete);
};

// I'm using nonblocking loosely here, it only means -EAGAIN can be returned in certain cases
static int ni_usb_nonblocking_send_bulk_msg(struct ni_usb_priv *ni_priv, void *data,
                                            int data_length, int *actual_data_length,
                                            int timeout_msecs)
{
        struct usb_device *usb_dev;
        int retval;
        unsigned int out_pipe;
        struct ni_usb_urb_ctx *context = &ni_priv->context;

        *actual_data_length = 0;
        mutex_lock(&ni_priv->bulk_transfer_lock);
        if (!ni_priv->bus_interface) {
                mutex_unlock(&ni_priv->bulk_transfer_lock);
                return -ENODEV;
        }
        if (ni_priv->bulk_urb) {
                mutex_unlock(&ni_priv->bulk_transfer_lock);
                return -EAGAIN;
        }
        ni_priv->bulk_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!ni_priv->bulk_urb) {
                mutex_unlock(&ni_priv->bulk_transfer_lock);
                return -ENOMEM;
        }
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        out_pipe = usb_sndbulkpipe(usb_dev, ni_priv->bulk_out_endpoint);
        init_completion(&context->complete);
        context->timed_out = 0;
        usb_fill_bulk_urb(ni_priv->bulk_urb, usb_dev, out_pipe, data, data_length,
                          &ni_usb_bulk_complete, context);

        if (timeout_msecs)
                mod_timer(&ni_priv->bulk_timer, jiffies + msecs_to_jiffies(timeout_msecs));

        retval = usb_submit_urb(ni_priv->bulk_urb, GFP_KERNEL);
        if (retval) {
                timer_delete_sync(&ni_priv->bulk_timer);
                usb_free_urb(ni_priv->bulk_urb);
                ni_priv->bulk_urb = NULL;
                dev_err(&usb_dev->dev, "failed to submit bulk out urb, retval=%i\n",
                        retval);
                mutex_unlock(&ni_priv->bulk_transfer_lock);
                return retval;
        }
        mutex_unlock(&ni_priv->bulk_transfer_lock);
        wait_for_completion(&context->complete);    // wait for ni_usb_bulk_complete
        if (context->timed_out) {
                usb_kill_urb(ni_priv->bulk_urb);
                dev_err(&usb_dev->dev, "killed urb due to timeout\n");
                retval = -ETIMEDOUT;
        } else {
                retval = ni_priv->bulk_urb->status;
        }

        timer_delete_sync(&ni_priv->bulk_timer);
        *actual_data_length = ni_priv->bulk_urb->actual_length;
        mutex_lock(&ni_priv->bulk_transfer_lock);
        usb_free_urb(ni_priv->bulk_urb);
        ni_priv->bulk_urb = NULL;
        mutex_unlock(&ni_priv->bulk_transfer_lock);
        return retval;
}

static int ni_usb_send_bulk_msg(struct ni_usb_priv *ni_priv, void *data, int data_length,
                                int *actual_data_length, int timeout_msecs)
{
        int retval;
        int timeout_msecs_remaining = timeout_msecs;

        retval = ni_usb_nonblocking_send_bulk_msg(ni_priv, data, data_length, actual_data_length,
                                                  timeout_msecs_remaining);
        while (retval == -EAGAIN && (timeout_msecs == 0 || timeout_msecs_remaining > 0)) {
                usleep_range(1000, 1500);
                retval = ni_usb_nonblocking_send_bulk_msg(ni_priv, data, data_length,
                                                          actual_data_length,
                                                          timeout_msecs_remaining);
                if (timeout_msecs != 0)
                        --timeout_msecs_remaining;
        }
        if (timeout_msecs != 0 && timeout_msecs_remaining <= 0)
                return -ETIMEDOUT;
        return retval;
}

// I'm using nonblocking loosely here, it only means -EAGAIN can be returned in certain cases
static int ni_usb_nonblocking_receive_bulk_msg(struct ni_usb_priv *ni_priv,
                                               void *data, int data_length,
                                               int *actual_data_length, int timeout_msecs,
                                               int interruptible)
{
        struct usb_device *usb_dev;
        int retval;
        unsigned int in_pipe;
        struct ni_usb_urb_ctx *context = &ni_priv->context;

        *actual_data_length = 0;
        mutex_lock(&ni_priv->bulk_transfer_lock);
        if (!ni_priv->bus_interface) {
                mutex_unlock(&ni_priv->bulk_transfer_lock);
                return -ENODEV;
        }
        if (ni_priv->bulk_urb) {
                mutex_unlock(&ni_priv->bulk_transfer_lock);
                return -EAGAIN;
        }
        ni_priv->bulk_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!ni_priv->bulk_urb) {
                mutex_unlock(&ni_priv->bulk_transfer_lock);
                return -ENOMEM;
        }
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        in_pipe = usb_rcvbulkpipe(usb_dev, ni_priv->bulk_in_endpoint);
        init_completion(&context->complete);
        context->timed_out = 0;
        usb_fill_bulk_urb(ni_priv->bulk_urb, usb_dev, in_pipe, data, data_length,
                          &ni_usb_bulk_complete, context);

        if (timeout_msecs)
                mod_timer(&ni_priv->bulk_timer, jiffies + msecs_to_jiffies(timeout_msecs));

        retval = usb_submit_urb(ni_priv->bulk_urb, GFP_KERNEL);
        if (retval) {
                timer_delete_sync(&ni_priv->bulk_timer);
                usb_free_urb(ni_priv->bulk_urb);
                ni_priv->bulk_urb = NULL;
                dev_err(&usb_dev->dev, "failed to submit bulk in urb, retval=%i\n", retval);
                mutex_unlock(&ni_priv->bulk_transfer_lock);
                return retval;
        }
        mutex_unlock(&ni_priv->bulk_transfer_lock);
        if (interruptible) {
                if (wait_for_completion_interruptible(&context->complete)) {
                        /*
                         * If we got interrupted by a signal while
                         * waiting for the usb gpib to respond, we
                         * should send a stop command so it will
                         * finish up with whatever it was doing and
                         * send its response now.
                         */
                        ni_usb_stop(ni_priv);
                        retval = -ERESTARTSYS;
                        /*
                         * now do an uninterruptible wait, it shouldn't take long
                         * for the board to respond now.
                         */
                        wait_for_completion(&context->complete);
                }
        } else {
                wait_for_completion(&context->complete);
        }
        if (context->timed_out) {
                usb_kill_urb(ni_priv->bulk_urb);
                dev_err(&usb_dev->dev, "killed urb due to timeout\n");
                retval = -ETIMEDOUT;
        } else {
                if (ni_priv->bulk_urb->status)
                        retval = ni_priv->bulk_urb->status;
        }
        timer_delete_sync(&ni_priv->bulk_timer);
        *actual_data_length = ni_priv->bulk_urb->actual_length;
        mutex_lock(&ni_priv->bulk_transfer_lock);
        usb_free_urb(ni_priv->bulk_urb);
        ni_priv->bulk_urb = NULL;
        mutex_unlock(&ni_priv->bulk_transfer_lock);
        return retval;
}

static int ni_usb_receive_bulk_msg(struct ni_usb_priv *ni_priv, void *data,
                                   int data_length, int *actual_data_length, int timeout_msecs,
                                   int interruptible)
{
        int retval;
        int timeout_msecs_remaining = timeout_msecs;

        retval = ni_usb_nonblocking_receive_bulk_msg(ni_priv, data, data_length,
                                                     actual_data_length, timeout_msecs_remaining,
                                                     interruptible);
        while (retval == -EAGAIN && (timeout_msecs == 0 || timeout_msecs_remaining > 0)) {
                usleep_range(1000, 1500);
                retval = ni_usb_nonblocking_receive_bulk_msg(ni_priv, data, data_length,
                                                             actual_data_length,
                                                             timeout_msecs_remaining,
                                                             interruptible);
                if (timeout_msecs != 0)
                        --timeout_msecs_remaining;
        }
        if (timeout_msecs && timeout_msecs_remaining <= 0)
                return -ETIMEDOUT;
        return retval;
}

static int ni_usb_receive_control_msg(struct ni_usb_priv *ni_priv, __u8 request,
                                      __u8 requesttype, __u16 value, __u16 index,
                                      void *data, __u16 size, int timeout_msecs)
{
        struct usb_device *usb_dev;
        int retval;
        unsigned int in_pipe;

        mutex_lock(&ni_priv->control_transfer_lock);
        if (!ni_priv->bus_interface) {
                mutex_unlock(&ni_priv->control_transfer_lock);
                return -ENODEV;
        }
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        in_pipe = usb_rcvctrlpipe(usb_dev, 0);
        retval = usb_control_msg(usb_dev, in_pipe, request, requesttype, value, index, data,
                                 size, timeout_msecs);
        mutex_unlock(&ni_priv->control_transfer_lock);
        return retval;
}

static void ni_usb_soft_update_status(struct gpib_board *board, unsigned int ni_usb_ibsta,
                                      unsigned int clear_mask)
{
        static const unsigned int ni_usb_ibsta_mask = SRQI | ATN | CIC | REM | LACS | TACS | LOK;

        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        unsigned int need_monitoring_bits = ni_usb_ibsta_monitor_mask;
        unsigned long flags;

        board->status &= ~clear_mask;
        board->status &= ~ni_usb_ibsta_mask;
        board->status |= ni_usb_ibsta & ni_usb_ibsta_mask;
        if (ni_usb_ibsta & DCAS)
                push_gpib_event(board, EVENT_DEV_CLR);
        if (ni_usb_ibsta & DTAS)
                push_gpib_event(board, EVENT_DEV_TRG);

        spin_lock_irqsave(&board->spinlock, flags);
/* remove set status bits from monitored set why ?***/
        ni_priv->monitored_ibsta_bits &= ~ni_usb_ibsta;
        need_monitoring_bits &= ~ni_priv->monitored_ibsta_bits; /* mm - monitored set */
        spin_unlock_irqrestore(&board->spinlock, flags);
        dev_dbg(&usb_dev->dev, "need_monitoring_bits=0x%x\n", need_monitoring_bits);

        if (need_monitoring_bits & ~ni_usb_ibsta)
                ni_usb_set_interrupt_monitor(board, ni_usb_ibsta_monitor_mask);
        else if (need_monitoring_bits & ni_usb_ibsta)
                wake_up_interruptible(&board->wait);

        dev_dbg(&usb_dev->dev, "ibsta=0x%x\n", ni_usb_ibsta);
}

static int ni_usb_parse_status_block(const u8 *buffer, struct ni_usb_status_block *status)
{
        u16 count;

        status->id = buffer[0];
        status->ibsta = (buffer[1] << 8) | buffer[2];
        status->error_code = buffer[3];
        count = buffer[4] | (buffer[5] << 8);
        count = ~count;
        count++;
        status->count = count;
        return 8;
};

static void ni_usb_dump_raw_block(const u8 *raw_data, int length)
{
        print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 8, 1, raw_data, length, true);
}

static int ni_usb_parse_register_read_block(const u8 *raw_data, unsigned int *results,
                                            int num_results)
{
        int i = 0;
        int j;
        int unexpected = 0;
        static const int results_per_chunk = 3;

        for (j = 0; j < num_results;) {
                int k;

                if (raw_data[i++] != NIUSB_REGISTER_READ_DATA_START_ID) {
                        pr_err("parse error: wrong start id\n");
                        unexpected = 1;
                }
                for (k = 0; k < results_per_chunk && j < num_results; ++k)
                        results[j++] = raw_data[i++];
        }
        while (i % 4)
                i++;
        if (raw_data[i++] != NIUSB_REGISTER_READ_DATA_END_ID) {
                pr_err("parse error: wrong end id\n");
                unexpected = 1;
        }
        if (raw_data[i++] % results_per_chunk != num_results % results_per_chunk) {
                pr_err("parse error: wrong count=%i for NIUSB_REGISTER_READ_DATA_END\n",
                       (int)raw_data[i - 1]);
                unexpected = 1;
        }
        while (i % 4) {
                if (raw_data[i++] != 0) {
                        pr_err("unexpected data: raw_data[%i]=0x%x, expected 0\n",
                               i - 1, (int)raw_data[i - 1]);
                        unexpected = 1;
                }
        }
        if (unexpected)
                ni_usb_dump_raw_block(raw_data, i);
        return i;
}

static int ni_usb_parse_termination_block(const u8 *buffer)
{
        int i = 0;

        if (buffer[i++] != NIUSB_TERM_ID ||
            buffer[i++] != 0x0 ||
            buffer[i++] != 0x0 ||
            buffer[i++] != 0x0) {
                pr_err("received unexpected termination block\n");
                pr_err(" expected: 0x%x 0x%x 0x%x 0x%x\n", NIUSB_TERM_ID, 0x0, 0x0, 0x0);
                pr_err(" received: 0x%x 0x%x 0x%x 0x%x\n",
                       buffer[i - 4], buffer[i - 3], buffer[i - 2], buffer[i - 1]);
        }
        return i;
};

static int parse_board_ibrd_readback(const u8 *raw_data, struct ni_usb_status_block *status,
                                     u8 *parsed_data, int parsed_data_length,
                                     int *actual_bytes_read)
{
        static const int ibrd_data_block_length = 0xf;
        static const int ibrd_extended_data_block_length = 0x1e;
        int data_block_length = 0;
        int i = 0;
        int j = 0;
        int k;
        int num_data_blocks = 0;
        struct ni_usb_status_block register_write_status;
        int unexpected = 0;

        while (raw_data[i] == NIUSB_IBRD_DATA_ID || raw_data[i] == NIUSB_IBRD_EXTENDED_DATA_ID) {
                if (raw_data[i] == NIUSB_IBRD_DATA_ID) {
                        data_block_length = ibrd_data_block_length;
                } else if (raw_data[i] == NIUSB_IBRD_EXTENDED_DATA_ID) {
                        data_block_length = ibrd_extended_data_block_length;
                        if (raw_data[++i] !=  0)        {
                                pr_err("unexpected data: raw_data[%i]=0x%x, expected 0\n",
                                       i, (int)raw_data[i]);
                                unexpected = 1;
                        }
                } else {
                        pr_err("Unexpected NIUSB_IBRD ID\n");
                        return -EINVAL;
                }
                ++i;
                for (k = 0; k < data_block_length; k++) {
                        if (j < parsed_data_length)
                                parsed_data[j++] = raw_data[i++];
                        else
                                ++i;
                }
                ++num_data_blocks;
        }
        i += ni_usb_parse_status_block(&raw_data[i], status);
        if (status->id != NIUSB_IBRD_STATUS_ID) {
                pr_err("bug: status->id=%i, != ibrd_status_id\n", status->id);
                return -EIO;
        }
        i++;
        if (num_data_blocks) {
                *actual_bytes_read = (num_data_blocks - 1) * data_block_length + raw_data[i++];
        } else {
                ++i;
                *actual_bytes_read = 0;
        }
        if (*actual_bytes_read > j)
                pr_err("bug: discarded data. actual_bytes_read=%i, j=%i\n", *actual_bytes_read, j);
        for (k = 0; k < 2; k++)
                if (raw_data[i++] != 0) {
                        pr_err("unexpected data: raw_data[%i]=0x%x, expected 0\n",
                               i - 1, (int)raw_data[i - 1]);
                        unexpected = 1;
                }
        i += ni_usb_parse_status_block(&raw_data[i], &register_write_status);
        if (register_write_status.id != NIUSB_REG_WRITE_ID) {
                pr_err("unexpected data: register write status id=0x%x, expected 0x%x\n",
                       register_write_status.id, NIUSB_REG_WRITE_ID);
                unexpected = 1;
        }
        if (raw_data[i++] != 2) {
                pr_err("unexpected data: register write count=%i, expected 2\n",
                       (int)raw_data[i - 1]);
                unexpected = 1;
        }
        for (k = 0; k < 3; k++)
                if (raw_data[i++] != 0) {
                        pr_err("unexpected data: raw_data[%i]=0x%x, expected 0\n",
                               i - 1, (int)raw_data[i - 1]);
                        unexpected = 1;
                }
        i += ni_usb_parse_termination_block(&raw_data[i]);
        if (unexpected)
                ni_usb_dump_raw_block(raw_data, i);
        return i;
}

static  int ni_usb_parse_reg_write_status_block(const u8 *raw_data,
                                                struct ni_usb_status_block *status,
                                                int *writes_completed)
{
        int i = 0;

        i += ni_usb_parse_status_block(raw_data, status);
        *writes_completed = raw_data[i++];
        while (i % 4)
                i++;
        return i;
}

static int ni_usb_write_registers(struct ni_usb_priv *ni_priv,
                                  const struct ni_usb_register *writes, int num_writes,
                                  unsigned int *ibsta)
{
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        int retval;
        u8 *out_data, *in_data;
        int out_data_length;
        static const int in_data_length = 0x20;
        int bytes_written = 0, bytes_read = 0;
        int i = 0;
        int j;
        struct ni_usb_status_block status;
        static const int bytes_per_write = 3;
        int reg_writes_completed;

        out_data_length = num_writes * bytes_per_write + 0x10;
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return -ENOMEM;
        i += ni_usb_bulk_register_write_header(&out_data[i], num_writes);
        for (j = 0; j < num_writes; j++)
                i += ni_usb_bulk_register_write(&out_data[i], writes[j]);
        while (i % 4)
                out_data[i++] = 0x00;
        i += ni_usb_bulk_termination(&out_data[i]);

        mutex_lock(&ni_priv->addressed_transfer_lock);

        retval = ni_usb_send_bulk_msg(ni_priv, out_data, i, &bytes_written, 1000);
        kfree(out_data);
        if (retval) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, bytes_written=%i, i=%i\n",
                        retval, bytes_written, i);
                return retval;
        }

        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                return -ENOMEM;
        }
        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length, &bytes_read, 1000, 0);
        if (retval || bytes_read != 16) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, bytes_read=%i\n",
                        retval, bytes_read);
                ni_usb_dump_raw_block(in_data, bytes_read);
                kfree(in_data);
                return retval ?: -EINVAL;
        }

        mutex_unlock(&ni_priv->addressed_transfer_lock);

        ni_usb_parse_reg_write_status_block(in_data, &status, &reg_writes_completed);
        // FIXME parse extra 09 status bits and termination
        kfree(in_data);
        if (status.id != NIUSB_REG_WRITE_ID) {
                dev_err(&usb_dev->dev, "parse error, id=0x%x != NIUSB_REG_WRITE_ID\n", status.id);
                return -EIO;
        }
        if (status.error_code) {
                dev_err(&usb_dev->dev, "nonzero error code 0x%x\n", status.error_code);
                return -EIO;
        }
        if (reg_writes_completed != num_writes) {
                dev_err(&usb_dev->dev, "reg_writes_completed=%i, num_writes=%i\n",
                        reg_writes_completed, num_writes);
                return -EIO;
        }
        if (ibsta)
                *ibsta = status.ibsta;
        return 0;
}

// interface functions
static int ni_usb_read(struct gpib_board *board, u8 *buffer, size_t length,
                       int *end, size_t *bytes_read)
{
        int retval, parse_retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        u8 *out_data, *in_data;
        static const int out_data_length = 0x20;
        int in_data_length;
        int usb_bytes_written = 0, usb_bytes_read = 0;
        int i = 0;
        int complement_count;
        int actual_length;
        struct ni_usb_status_block status;
        static const int max_read_length = 0xffff;
        struct ni_usb_register reg;

        *bytes_read = 0;
        if (!ni_priv->bus_interface)
                return -ENODEV;
        if (length > max_read_length)
                return -EINVAL;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return -ENOMEM;
        out_data[i++] = 0x0a;
        out_data[i++] = ni_priv->eos_mode >> 8;
        out_data[i++] = ni_priv->eos_char;
        out_data[i++] = ni_usb_timeout_code(board->usec_timeout);
        complement_count = length - 1;
        complement_count = ~complement_count;
        out_data[i++] = complement_count & 0xff;
        out_data[i++] = (complement_count >> 8) & 0xff;
        out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        i += ni_usb_bulk_register_write_header(&out_data[i], 2);
        reg.device = NIUSB_SUBDEV_TNT4882;
        reg.address = nec7210_to_tnt4882_offset(AUXMR);
        reg.value = AUX_HLDI;
        i += ni_usb_bulk_register_write(&out_data[i], reg);
        reg.value = AUX_CLEAR_END;
        i += ni_usb_bulk_register_write(&out_data[i], reg);
        while (i % 4)   // pad with zeros to 4-byte boundary
                out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);

        mutex_lock(&ni_priv->addressed_transfer_lock);

        retval = ni_usb_send_bulk_msg(ni_priv, out_data, i, &usb_bytes_written, 1000);
        kfree(out_data);
        if (retval || usb_bytes_written != i) {
                if (retval == 0)
                        retval = -EIO;
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, usb_bytes_written=%i, i=%i\n",
                        retval, usb_bytes_written, i);
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                return retval;
        }

        in_data_length = (length / 30 + 1) * 0x20 + 0x20;
        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                return -ENOMEM;
        }
        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length, &usb_bytes_read,
                                         ni_usb_timeout_msecs(board->usec_timeout), 1);

        mutex_unlock(&ni_priv->addressed_transfer_lock);

        if (retval == -ERESTARTSYS) {
        } else if (retval) {
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, usb_bytes_read=%i\n",
                        retval, usb_bytes_read);
                kfree(in_data);
                return retval;
        }
        parse_retval = parse_board_ibrd_readback(in_data, &status, buffer, length, &actual_length);
        if (parse_retval != usb_bytes_read) {
                if (parse_retval >= 0)
                        parse_retval = -EIO;
                dev_err(&usb_dev->dev, "retval=%i usb_bytes_read=%i\n",
                        parse_retval, usb_bytes_read);
                kfree(in_data);
                return parse_retval;
        }
        if (actual_length != length - status.count) {
                dev_err(&usb_dev->dev, "actual_length=%i expected=%li\n",
                        actual_length, (long)(length - status.count));
                ni_usb_dump_raw_block(in_data, usb_bytes_read);
        }
        kfree(in_data);
        switch (status.error_code) {
        case NIUSB_NO_ERROR:
                retval = 0;
                break;
        case NIUSB_ABORTED_ERROR:
                /*
                 * this is expected if ni_usb_receive_bulk_msg got
                 * interrupted by a signal and returned -ERESTARTSYS
                 */
                break;
        case NIUSB_ATN_STATE_ERROR:
                if (status.ibsta & DCAS) {
                        retval = -EINTR;
                } else {
                        retval = -EIO;
                        dev_dbg(&usb_dev->dev, "read when ATN set stat: 0x%06x\n", status.ibsta);
                }
                break;
        case NIUSB_ADDRESSING_ERROR:
                retval = -EIO;
                break;
        case NIUSB_TIMEOUT_ERROR:
                retval = -ETIMEDOUT;
                break;
        case NIUSB_EOSMODE_ERROR:
                dev_err(&usb_dev->dev, "driver bug, we should have been able to avoid NIUSB_EOSMODE_ERROR.\n");
                retval = -EINVAL;
                break;
        default:
                dev_err(&usb_dev->dev, "unknown error code=%i\n",  status.error_code);
                retval = -EIO;
                break;
        }
        ni_usb_soft_update_status(board, status.ibsta, 0);
        if (status.ibsta & END)
                *end = 1;
        else
                *end = 0;
        *bytes_read = actual_length;
        return retval;
}

static int ni_usb_write(struct gpib_board *board, u8 *buffer, size_t length,
                        int send_eoi, size_t *bytes_written)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        u8 *out_data, *in_data;
        int out_data_length;
        static const int in_data_length = 0x10;
        int usb_bytes_written = 0, usb_bytes_read = 0;
        int i = 0, j;
        int complement_count;
        struct ni_usb_status_block status;
        static const int max_write_length = 0xffff;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        if (length > max_write_length)
                return -EINVAL;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        out_data_length = length + 0x10;
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return -ENOMEM;
        out_data[i++] = 0x0d;
        complement_count = length - 1;
        complement_count = ~complement_count;
        out_data[i++] = complement_count & 0xff;
        out_data[i++] = (complement_count >> 8) & 0xff;
        out_data[i++] = ni_usb_timeout_code(board->usec_timeout);
        out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        if (send_eoi)
                out_data[i++] = 0x8;
        else
                out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        for (j = 0; j < length; j++)
                out_data[i++] = buffer[j];
        while (i % 4)   // pad with zeros to 4-byte boundary
                out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);

        mutex_lock(&ni_priv->addressed_transfer_lock);

        retval = ni_usb_send_bulk_msg(ni_priv, out_data, i, &usb_bytes_written,
                                      ni_usb_timeout_msecs(board->usec_timeout));
        kfree(out_data);
        if (retval || usb_bytes_written != i)   {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, usb_bytes_written=%i, i=%i\n",
                        retval, usb_bytes_written, i);
                return retval;
        }

        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                return -ENOMEM;
        }
        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length, &usb_bytes_read,
                                         ni_usb_timeout_msecs(board->usec_timeout), 1);

        mutex_unlock(&ni_priv->addressed_transfer_lock);

        if ((retval && retval != -ERESTARTSYS) || usb_bytes_read != 12) {
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, usb_bytes_read=%i\n",
                        retval, usb_bytes_read);
                kfree(in_data);
                return retval;
        }
        ni_usb_parse_status_block(in_data, &status);
        kfree(in_data);
        switch  (status.error_code) {
        case NIUSB_NO_ERROR:
                retval = 0;
                break;
        case NIUSB_ABORTED_ERROR:
                /*
                 * this is expected if ni_usb_receive_bulk_msg got
                 * interrupted by a signal and returned -ERESTARTSYS
                 */
                break;
        case NIUSB_ADDRESSING_ERROR:
                dev_err(&usb_dev->dev, "Addressing error retval %d error code=%i\n",
                        retval, status.error_code);
                retval = -ENXIO;
                break;
        case NIUSB_NO_LISTENER_ERROR:
                retval = -ECOMM;
                break;
        case NIUSB_TIMEOUT_ERROR:
                retval = -ETIMEDOUT;
                break;
        default:
                dev_err(&usb_dev->dev, "unknown error code=%i\n", status.error_code);
                retval = -EPIPE;
                break;
        }
        ni_usb_soft_update_status(board, status.ibsta, 0);
        *bytes_written = length - status.count;
        return retval;
}

static int ni_usb_command_chunk(struct gpib_board *board, u8 *buffer, size_t length,
                                size_t *command_bytes_written)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        u8 *out_data, *in_data;
        int out_data_length;
        static const int in_data_length = 0x10;
        int bytes_written = 0, bytes_read = 0;
        int i = 0, j;
        unsigned int complement_count;
        struct ni_usb_status_block status;
        // usb-b gives error 4 if you try to send more than 16 command bytes at once
        static const int max_command_length = 0x10;

        *command_bytes_written = 0;
        if (!ni_priv->bus_interface)
                return -ENODEV;
        if (length > max_command_length)
                length = max_command_length;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        out_data_length = length + 0x10;
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return -ENOMEM;
        out_data[i++] = 0x0c;
        complement_count = length - 1;
        complement_count = ~complement_count;
        out_data[i++] = complement_count;
        out_data[i++] = 0x0;
        out_data[i++] = ni_usb_timeout_code(board->usec_timeout);
        for (j = 0; j < length; j++)
                out_data[i++] = buffer[j];
        while (i % 4)   // pad with zeros to 4-byte boundary
                out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);

        mutex_lock(&ni_priv->addressed_transfer_lock);

        retval = ni_usb_send_bulk_msg(ni_priv, out_data, i, &bytes_written,
                                      ni_usb_timeout_msecs(board->usec_timeout));
        kfree(out_data);
        if (retval || bytes_written != i) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, bytes_written=%i, i=%i\n",
                        retval, bytes_written, i);
                return retval;
        }

        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                return -ENOMEM;
        }

        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length, &bytes_read,
                                         ni_usb_timeout_msecs(board->usec_timeout), 1);

        mutex_unlock(&ni_priv->addressed_transfer_lock);

        if ((retval && retval != -ERESTARTSYS) || bytes_read != 12) {
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, bytes_read=%i\n",
                        retval, bytes_read);
                kfree(in_data);
                return retval;
        }
        ni_usb_parse_status_block(in_data, &status);
        kfree(in_data);
        *command_bytes_written = length - status.count;
        switch (status.error_code) {
        case NIUSB_NO_ERROR:
                break;
        case NIUSB_ABORTED_ERROR:
                /*
                 * this is expected if ni_usb_receive_bulk_msg got
                 * interrupted by a signal and returned -ERESTARTSYS
                 */
                break;
        case NIUSB_NO_BUS_ERROR:
                return -ENOTCONN;
        case NIUSB_EOSMODE_ERROR:
                dev_err(&usb_dev->dev, "got eosmode error. Driver bug?\n");
                return -EIO;
        case NIUSB_TIMEOUT_ERROR:
                return -ETIMEDOUT;
        default:
                dev_err(&usb_dev->dev, "unknown error code=%i\n", status.error_code);
                return -EIO;
        }
        ni_usb_soft_update_status(board, status.ibsta, 0);
        return 0;
}

static int ni_usb_command(struct gpib_board *board, u8 *buffer, size_t length,
                          size_t *bytes_written)
{
        size_t count;
        int retval;

        *bytes_written = 0;
        while (*bytes_written < length) {
                retval = ni_usb_command_chunk(board, buffer + *bytes_written,
                                              length - *bytes_written, &count);
                *bytes_written += count;
                if (retval < 0)
                        return retval;
        }
        return 0;
}

static int ni_usb_take_control(struct gpib_board *board, int synchronous)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        u8 *out_data, *in_data;
        static const int out_data_length = 0x10;
        static const int  in_data_length = 0x10;
        int bytes_written = 0, bytes_read = 0;
        int i = 0;
        struct ni_usb_status_block status;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return -ENOMEM;
        out_data[i++] = NIUSB_IBCAC_ID;
        if (synchronous)
                out_data[i++] = 0x1;
        else
                out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);

        mutex_lock(&ni_priv->addressed_transfer_lock);

        retval = ni_usb_send_bulk_msg(ni_priv, out_data, i, &bytes_written, 1000);
        kfree(out_data);
        if (retval || bytes_written != i) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, bytes_written=%i, i=%i\n",
                        retval, bytes_written, i);
                return retval;
        }

        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                return -ENOMEM;
        }
        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length, &bytes_read, 1000, 1);

        mutex_unlock(&ni_priv->addressed_transfer_lock);

        if ((retval && retval != -ERESTARTSYS) || bytes_read != 12) {
                if (retval == 0)
                        retval = -EIO;
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, bytes_read=%i\n",
                        retval, bytes_read);
                kfree(in_data);
                return retval;
        }
        ni_usb_parse_status_block(in_data, &status);
        kfree(in_data);
        ni_usb_soft_update_status(board, status.ibsta, 0);
        return retval;
}

static int ni_usb_go_to_standby(struct gpib_board *board)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        u8 *out_data, *in_data;
        static const int out_data_length = 0x10;
        static const int  in_data_length = 0x20;
        int bytes_written = 0, bytes_read = 0;
        int i = 0;
        struct ni_usb_status_block status;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return -ENOMEM;

        out_data[i++] = NIUSB_IBGTS_ID;
        out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);

        mutex_lock(&ni_priv->addressed_transfer_lock);

        retval = ni_usb_send_bulk_msg(ni_priv, out_data, i, &bytes_written, 1000);
        kfree(out_data);
        if (retval || bytes_written != i) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, bytes_written=%i, i=%i\n",
                        retval, bytes_written, i);
                return retval;
        }

        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                return -ENOMEM;
        }
        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length, &bytes_read, 1000, 0);

        mutex_unlock(&ni_priv->addressed_transfer_lock);

        if (retval || bytes_read != 12) {
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, bytes_read=%i\n",
                        retval, bytes_read);
                kfree(in_data);
                return retval;
        }
        ni_usb_parse_status_block(in_data, &status);
        kfree(in_data);
        if (status.id != NIUSB_IBGTS_ID)
                dev_err(&usb_dev->dev, "bug: status.id 0x%x != INUSB_IBGTS_ID\n", status.id);
        ni_usb_soft_update_status(board, status.ibsta, 0);
        return 0;
}

static int ni_usb_request_system_control(struct gpib_board *board, int request_control)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        int i = 0;
        struct ni_usb_register writes[4];
        unsigned int ibsta;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        if (request_control) {
                writes[i].device = NIUSB_SUBDEV_TNT4882;
                writes[i].address = CMDR;
                writes[i].value = SETSC;
                i++;
                writes[i].device = NIUSB_SUBDEV_TNT4882;
                writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
                writes[i].value = AUX_CIFC;
                i++;
        } else {
                writes[i].device = NIUSB_SUBDEV_TNT4882;
                writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
                writes[i].value = AUX_CREN;
                i++;
                writes[i].device = NIUSB_SUBDEV_TNT4882;
                writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
                writes[i].value = AUX_CIFC;
                i++;
                writes[i].device = NIUSB_SUBDEV_TNT4882;
                writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
                writes[i].value = AUX_DSC;
                i++;
                writes[i].device = NIUSB_SUBDEV_TNT4882;
                writes[i].address = CMDR;
                writes[i].value = CLRSC;
                i++;
        }
        retval = ni_usb_write_registers(ni_priv, writes, i, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return retval;
        }
        if (!request_control)
                ni_priv->ren_state = 0;
        ni_usb_soft_update_status(board, ibsta, 0);
        return 0;
}

// FIXME maybe the interface should have a "pulse interface clear" function that can return an error?
static void ni_usb_interface_clear(struct gpib_board *board, int assert)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        u8 *out_data, *in_data;
        static const int out_data_length = 0x10;
        static const int  in_data_length = 0x10;
        int bytes_written = 0, bytes_read = 0;
        int i = 0;
        struct ni_usb_status_block status;

        if (!ni_priv->bus_interface)
                return; // -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
// FIXME: we are going to pulse when assert is true, and ignore otherwise
        if (assert == 0)
                return;
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return;
        out_data[i++] = NIUSB_IBSIC_ID;
        out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);
        retval = ni_usb_send_bulk_msg(ni_priv, out_data, i, &bytes_written, 1000);
        kfree(out_data);
        if (retval || bytes_written != i) {
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, bytes_written=%i, i=%i\n",
                        retval, bytes_written, i);
                return;
        }
        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data)
                return;

        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length, &bytes_read, 1000, 0);
        if (retval || bytes_read != 12) {
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, bytes_read=%i\n",
                        retval, bytes_read);
                kfree(in_data);
                return;
        }
        ni_usb_parse_status_block(in_data, &status);
        kfree(in_data);
        ni_usb_soft_update_status(board, status.ibsta, 0);
}

static void ni_usb_remote_enable(struct gpib_board *board, int enable)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        struct ni_usb_register reg;
        unsigned int ibsta;

        if (!ni_priv->bus_interface)
                return; // -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        reg.device = NIUSB_SUBDEV_TNT4882;
        reg.address = nec7210_to_tnt4882_offset(AUXMR);
        if (enable)
                reg.value = AUX_SREN;
        else
                reg.value = AUX_CREN;
        retval = ni_usb_write_registers(ni_priv, &reg, 1, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return; //retval;
        }
        ni_priv->ren_state = enable;
        ni_usb_soft_update_status(board, ibsta, 0);
        return;// 0;
}

static int ni_usb_enable_eos(struct gpib_board *board, u8 eos_byte, int compare_8_bits)
{
        struct ni_usb_priv *ni_priv = board->private_data;

        ni_priv->eos_char = eos_byte;
        ni_priv->eos_mode |= REOS;
        if (compare_8_bits)
                ni_priv->eos_mode |= BIN;
        else
                ni_priv->eos_mode &= ~BIN;
        return 0;
}

static void ni_usb_disable_eos(struct gpib_board *board)
{
        struct ni_usb_priv *ni_priv = board->private_data;
        /*
         * adapter gets unhappy if you don't zero all the bits
         * for the eos mode and eos char (returns error 4 on reads).
         */
        ni_priv->eos_mode = 0;
        ni_priv->eos_char = 0;
}

static unsigned int ni_usb_update_status(struct gpib_board *board, unsigned int clear_mask)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        static const int buffer_length = 8;
        u8 *buffer;
        struct ni_usb_status_block status;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        buffer = kmalloc(buffer_length, GFP_KERNEL);
        if (!buffer)
                return board->status;

        retval = ni_usb_receive_control_msg(ni_priv, NI_USB_WAIT_REQUEST, USB_DIR_IN |
                                            USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                            0x200, 0x0, buffer, buffer_length, 1000);
        if (retval != buffer_length) {
                dev_err(&usb_dev->dev, "usb_control_msg returned %i\n", retval);
                kfree(buffer);
                return board->status;
        }
        ni_usb_parse_status_block(buffer, &status);
        kfree(buffer);
        ni_usb_soft_update_status(board, status.ibsta, clear_mask);
        return board->status;
}

// tells ni-usb to immediately stop an ongoing i/o operation
static void ni_usb_stop(struct ni_usb_priv *ni_priv)
{
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        int retval;
        static const int buffer_length = 8;
        u8 *buffer;
        struct ni_usb_status_block status;

        buffer = kmalloc(buffer_length, GFP_KERNEL);
        if (!buffer)
                return;

        retval = ni_usb_receive_control_msg(ni_priv, NI_USB_STOP_REQUEST, USB_DIR_IN |
                                            USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                            0x0, 0x0, buffer, buffer_length, 1000);
        if (retval != buffer_length) {
                dev_err(&usb_dev->dev, "usb_control_msg returned %i\n", retval);
                kfree(buffer);
                return;
        }
        ni_usb_parse_status_block(buffer, &status);
        kfree(buffer);
}

static int ni_usb_primary_address(struct gpib_board *board, unsigned int address)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        int i = 0;
        struct ni_usb_register writes[2];
        unsigned int ibsta;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(ADR);
        writes[i].value = address;
        i++;
        writes[i].device = NIUSB_SUBDEV_UNKNOWN2;
        writes[i].address = 0x0;
        writes[i].value = address;
        i++;
        retval = ni_usb_write_registers(ni_priv, writes, i, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return retval;
        }
        ni_usb_soft_update_status(board, ibsta, 0);
        return 0;
}

static int ni_usb_write_sad(struct ni_usb_register *writes, int address, int enable)
{
        unsigned int adr_bits, admr_bits;
        int i = 0;

        adr_bits = HR_ARS;
        admr_bits = HR_TRM0 | HR_TRM1;
        if (enable) {
                adr_bits |= address;
                admr_bits |= HR_ADM1;
        } else {
                adr_bits |= HR_DT | HR_DL;
                admr_bits |= HR_ADM0;
        }
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(ADR);
        writes[i].value = adr_bits;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(ADMR);
        writes[i].value = admr_bits;
        i++;
        writes[i].device = NIUSB_SUBDEV_UNKNOWN2;
        writes[i].address = 0x1;
        writes[i].value = enable ? MSA(address) : 0x0;
        i++;
        return i;
}

static int ni_usb_secondary_address(struct gpib_board *board, unsigned int address, int enable)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        int i = 0;
        struct ni_usb_register writes[3];
        unsigned int ibsta;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        i += ni_usb_write_sad(writes, address, enable);
        retval = ni_usb_write_registers(ni_priv, writes, i, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return retval;
        }
        ni_usb_soft_update_status(board, ibsta, 0);
        return 0;
}

static int ni_usb_parallel_poll(struct gpib_board *board, u8 *result)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        u8 *out_data, *in_data;
        static const int out_data_length = 0x10;
        static const int  in_data_length = 0x20;
        int bytes_written = 0, bytes_read = 0;
        int i = 0;
        int j = 0;
        struct ni_usb_status_block status;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return -ENOMEM;

        out_data[i++] = NIUSB_IBRPP_ID;
        out_data[i++] = 0xf0;   // FIXME: this should be the parallel poll timeout code
        out_data[i++] = 0x0;
        out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);
        /*FIXME: 1000 should use parallel poll timeout (not supported yet)*/
        retval = ni_usb_send_bulk_msg(ni_priv, out_data, i, &bytes_written, 1000);

        kfree(out_data);
        if (retval || bytes_written != i) {
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, bytes_written=%i, i=%i\n",
                        retval, bytes_written, i);
                return retval;
        }
        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data)
                return -ENOMEM;

        /*FIXME: should use parallel poll timeout (not supported yet)*/
        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length,
                                         &bytes_read, 1000, 1);

        if (retval && retval != -ERESTARTSYS)   {
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, bytes_read=%i\n",
                        retval, bytes_read);
                kfree(in_data);
                return retval;
        }
        j += ni_usb_parse_status_block(in_data, &status);
        *result = in_data[j++];
        kfree(in_data);
        ni_usb_soft_update_status(board, status.ibsta, 0);
        return retval;
}

static void ni_usb_parallel_poll_configure(struct gpib_board *board, u8 config)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        int i = 0;
        struct ni_usb_register writes[1];
        unsigned int ibsta;

        if (!ni_priv->bus_interface)
                return; // -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[i].value = PPR | config;
        i++;
        retval = ni_usb_write_registers(ni_priv, writes, i, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return;// retval;
        }
        ni_usb_soft_update_status(board, ibsta, 0);
        return;// 0;
}

static void ni_usb_parallel_poll_response(struct gpib_board *board, int ist)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        int i = 0;
        struct ni_usb_register writes[1];
        unsigned int ibsta;

        if (!ni_priv->bus_interface)
                return; // -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        if (ist)
                writes[i].value = AUX_SPPF;
        else
                writes[i].value = AUX_CPPF;
        i++;
        retval = ni_usb_write_registers(ni_priv, writes, i, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return;// retval;
        }
        ni_usb_soft_update_status(board, ibsta, 0);
        return;// 0;
}

static void ni_usb_serial_poll_response(struct gpib_board *board, u8 status)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        int i = 0;
        struct ni_usb_register writes[1];
        unsigned int ibsta;

        if (!ni_priv->bus_interface)
                return; // -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(SPMR);
        writes[i].value = status;
        i++;
        retval = ni_usb_write_registers(ni_priv, writes, i, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return;// retval;
        }
        ni_usb_soft_update_status(board, ibsta, 0);
        return;// 0;
}

static u8 ni_usb_serial_poll_status(struct gpib_board *board)
{
        return 0;
}

static void ni_usb_return_to_local(struct gpib_board *board)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        int i = 0;
        struct ni_usb_register writes[1];
        unsigned int ibsta;

        if (!ni_priv->bus_interface)
                return; // -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[i].value = AUX_RTL;
        i++;
        retval = ni_usb_write_registers(ni_priv, writes, i, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return;// retval;
        }
        ni_usb_soft_update_status(board, ibsta, 0);
        return;// 0;
}

static int ni_usb_line_status(const struct gpib_board *board)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        u8 *out_data, *in_data;
        static const int out_data_length = 0x20;
        static const int  in_data_length = 0x20;
        int bytes_written = 0, bytes_read = 0;
        int i = 0;
        unsigned int bsr_bits;
        int line_status = VALID_ALL;
        // NI windows driver reads 0xd(HSSEL), 0xc (ARD0), 0x1f (BSR)

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data)
                return -ENOMEM;

        /* line status gets called during ibwait */
        retval = mutex_trylock(&ni_priv->addressed_transfer_lock);

        if (retval == 0) {
                kfree(out_data);
                return -EBUSY;
        }
        i += ni_usb_bulk_register_read_header(&out_data[i], 1);
        i += ni_usb_bulk_register_read(&out_data[i], NIUSB_SUBDEV_TNT4882, BSR);
        while (i % 4)
                out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);
        retval = ni_usb_nonblocking_send_bulk_msg(ni_priv, out_data, i, &bytes_written, 1000);
        kfree(out_data);
        if (retval || bytes_written != i) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                if (retval != -EAGAIN)
                        dev_err(&usb_dev->dev, "send_bulk_msg returned %i, bytes_written=%i, i=%i\n",
                                retval, bytes_written, i);
                return retval;
        }

        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data) {
                mutex_unlock(&ni_priv->addressed_transfer_lock);
                return -ENOMEM;
        }
        retval = ni_usb_nonblocking_receive_bulk_msg(ni_priv, in_data, in_data_length,
                                                     &bytes_read, 1000, 0);

        mutex_unlock(&ni_priv->addressed_transfer_lock);

        if (retval) {
                if (retval != -EAGAIN)
                        dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, bytes_read=%i\n",
                                retval, bytes_read);
                kfree(in_data);
                return retval;
        }

        ni_usb_parse_register_read_block(in_data, &bsr_bits, 1);
        kfree(in_data);
        if (bsr_bits & BCSR_REN_BIT)
                line_status |= BUS_REN;
        if (bsr_bits & BCSR_IFC_BIT)
                line_status |= BUS_IFC;
        if (bsr_bits & BCSR_SRQ_BIT)
                line_status |= BUS_SRQ;
        if (bsr_bits & BCSR_EOI_BIT)
                line_status |= BUS_EOI;
        if (bsr_bits & BCSR_NRFD_BIT)
                line_status |= BUS_NRFD;
        if (bsr_bits & BCSR_NDAC_BIT)
                line_status |= BUS_NDAC;
        if (bsr_bits & BCSR_DAV_BIT)
                line_status |= BUS_DAV;
        if (bsr_bits & BCSR_ATN_BIT)
                line_status |= BUS_ATN;
        return line_status;
}

static int ni_usb_setup_t1_delay(struct ni_usb_register *reg, unsigned int nano_sec,
                                 unsigned int *actual_ns)
{
        int i = 0;

        *actual_ns = 2000;

        reg[i].device = NIUSB_SUBDEV_TNT4882;
        reg[i].address = nec7210_to_tnt4882_offset(AUXMR);
        if (nano_sec <= 1100)   {
                reg[i].value = AUXRI | USTD | SISB;
                *actual_ns = 1100;
        } else {
                reg[i].value = AUXRI | SISB;
        }
        i++;
        reg[i].device = NIUSB_SUBDEV_TNT4882;
        reg[i].address = nec7210_to_tnt4882_offset(AUXMR);
        if (nano_sec <= 500)    {
                reg[i].value = AUXRB | HR_TRI;
                *actual_ns = 500;
        } else {
                reg[i].value = AUXRB;
        }
        i++;
        reg[i].device = NIUSB_SUBDEV_TNT4882;
        reg[i].address = KEYREG;
        if (nano_sec <= 350) {
                reg[i].value = MSTD;
                *actual_ns = 350;
        } else {
                reg[i].value = 0x0;
        }
        i++;
        return i;
}

static int ni_usb_t1_delay(struct gpib_board *board, unsigned int nano_sec)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        struct ni_usb_register writes[3];
        unsigned int ibsta;
        unsigned int actual_ns;
        int i;

        if (!ni_priv->bus_interface)
                return -ENODEV;
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        i = ni_usb_setup_t1_delay(writes, nano_sec, &actual_ns);
        retval = ni_usb_write_registers(ni_priv, writes, i, &ibsta);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return retval;
        }
        board->t1_nano_sec = actual_ns;
        ni_usb_soft_update_status(board, ibsta, 0);
        return actual_ns;
}

static int ni_usb_allocate_private(struct gpib_board *board)
{
        struct ni_usb_priv *ni_priv;

        board->private_data = kzalloc_obj(struct ni_usb_priv);
        if (!board->private_data)
                return -ENOMEM;
        ni_priv = board->private_data;
        mutex_init(&ni_priv->bulk_transfer_lock);
        mutex_init(&ni_priv->control_transfer_lock);
        mutex_init(&ni_priv->interrupt_transfer_lock);
        mutex_init(&ni_priv->addressed_transfer_lock);
        return 0;
}

static void ni_usb_free_private(struct ni_usb_priv *ni_priv)
{
        usb_free_urb(ni_priv->interrupt_urb);
        kfree(ni_priv);
}

#define NUM_INIT_WRITES 26
static int ni_usb_setup_init(struct gpib_board *board, struct ni_usb_register *writes)
{
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        unsigned int mask, actual_ns;
        int i = 0;

        writes[i].device = NIUSB_SUBDEV_UNKNOWN3;
        writes[i].address = 0x10;
        writes[i].value = 0x0;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = CMDR;
        writes[i].value = SOFT_RESET;
        i++;
        writes[i].device =  NIUSB_SUBDEV_TNT4882;
        writes[i].address =  nec7210_to_tnt4882_offset(AUXMR);
        mask = AUXRA | HR_HLDA;
        if (ni_priv->eos_mode & BIN)
                mask |= HR_BIN;
        writes[i].value = mask;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = AUXCR;
        writes[i].value = mask;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = HSSEL;
        writes[i].value = TNT_ONE_CHIP_BIT;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[i].value = AUX_CR;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = IMR0;
        writes[i].value = TNT_IMR0_ALWAYS_BITS;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(IMR1);
        writes[i].value = 0x0;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address =  nec7210_to_tnt4882_offset(IMR2);
        writes[i].value = 0x0;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = IMR3;
        writes[i].value = 0x0;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[i].value = AUX_HLDI;
        i++;

        i += ni_usb_setup_t1_delay(&writes[i], board->t1_nano_sec, &actual_ns);

        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[i].value = AUXRG | NTNL_BIT;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = CMDR;
        if (board->master)
                mask = SETSC; // set system controller
        else
                mask = CLRSC; // clear system controller
        writes[i].value = mask;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[i].value = AUX_CIFC;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(ADR);
        writes[i].value = board->pad;
        i++;
        writes[i].device = NIUSB_SUBDEV_UNKNOWN2;
        writes[i].address = 0x0;
        writes[i].value = board->pad;
        i++;

        i += ni_usb_write_sad(&writes[i], board->sad, board->sad >= 0);

        writes[i].device = NIUSB_SUBDEV_UNKNOWN2;
        writes[i].address = 0x2; // could this be a timeout ?
        writes[i].value = 0xfd;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = 0xf; // undocumented address
        writes[i].value = 0x11;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[i].value = AUX_PON;
        i++;
        writes[i].device = NIUSB_SUBDEV_TNT4882;
        writes[i].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[i].value = AUX_CPPF;
        i++;
        if (i > NUM_INIT_WRITES) {
                dev_err(&usb_dev->dev, "bug!, buffer overrun, i=%i\n", i);
                return -EINVAL;
        }
        return i;
}

static int ni_usb_init(struct gpib_board *board)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        struct ni_usb_register *writes;
        unsigned int ibsta;
        int writes_len;

        writes = kmalloc_objs(*writes, NUM_INIT_WRITES);
        if (!writes)
                return -ENOMEM;

        writes_len = ni_usb_setup_init(board, writes);
        if (writes_len < 0) {
                kfree(writes);
                return writes_len;
        }

        retval = ni_usb_write_registers(ni_priv, writes, writes_len, &ibsta);
        kfree(writes);
        if (retval) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return retval;
        }
        ni_usb_soft_update_status(board, ibsta, 0);
        return 0;
}

static void ni_usb_interrupt_complete(struct urb *urb)
{
        struct gpib_board *board = urb->context;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        int retval;
        struct ni_usb_status_block status;
        unsigned long flags;

        switch (urb->status) {
                /* success */
        case 0:
                break;
                /* unlinked, don't resubmit */
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                return;
        default: /* other error, resubmit */
                retval = usb_submit_urb(ni_priv->interrupt_urb, GFP_ATOMIC);
                if (retval)
                        dev_err(&usb_dev->dev, "failed to resubmit interrupt urb\n");
                return;
        }

        ni_usb_parse_status_block(urb->transfer_buffer, &status);

        spin_lock_irqsave(&board->spinlock, flags);
        ni_priv->monitored_ibsta_bits &= ~status.ibsta;
        spin_unlock_irqrestore(&board->spinlock, flags);

        wake_up_interruptible(&board->wait);

        retval = usb_submit_urb(ni_priv->interrupt_urb, GFP_ATOMIC);
        if (retval)
                dev_err(&usb_dev->dev, "failed to resubmit interrupt urb\n");
}

static int ni_usb_set_interrupt_monitor(struct gpib_board *board, unsigned int monitored_bits)
{
        int retval;
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        static const int buffer_length = 8;
        u8 *buffer;
        struct ni_usb_status_block status;
        unsigned long flags;

        buffer = kmalloc(buffer_length, GFP_KERNEL);
        if (!buffer)
                return -ENOMEM;

        spin_lock_irqsave(&board->spinlock, flags);
        ni_priv->monitored_ibsta_bits = ni_usb_ibsta_monitor_mask & monitored_bits;
        spin_unlock_irqrestore(&board->spinlock, flags);
        retval = ni_usb_receive_control_msg(ni_priv, NI_USB_WAIT_REQUEST, USB_DIR_IN |
                                            USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                            0x300, ni_usb_ibsta_monitor_mask & monitored_bits,
                                            buffer, buffer_length, 1000);
        if (retval != buffer_length) {
                dev_err(&usb_dev->dev, "usb_control_msg returned %i\n", retval);
                kfree(buffer);
                return -1;
        }
        ni_usb_parse_status_block(buffer, &status);
        kfree(buffer);
        return 0;
}

static int ni_usb_setup_urbs(struct gpib_board *board)
{
        struct ni_usb_priv *ni_priv = board->private_data;
        struct usb_device *usb_dev;
        int int_pipe;
        int retval;

        if (ni_priv->interrupt_in_endpoint < 0)
                return 0;

        mutex_lock(&ni_priv->interrupt_transfer_lock);
        if (!ni_priv->bus_interface) {
                mutex_unlock(&ni_priv->interrupt_transfer_lock);
                return -ENODEV;
        }
        ni_priv->interrupt_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!ni_priv->interrupt_urb) {
                mutex_unlock(&ni_priv->interrupt_transfer_lock);
                return -ENOMEM;
        }
        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        int_pipe = usb_rcvintpipe(usb_dev, ni_priv->interrupt_in_endpoint);
        usb_fill_int_urb(ni_priv->interrupt_urb, usb_dev, int_pipe, ni_priv->interrupt_buffer,
                         sizeof(ni_priv->interrupt_buffer), &ni_usb_interrupt_complete, board, 1);
        retval = usb_submit_urb(ni_priv->interrupt_urb, GFP_KERNEL);
        mutex_unlock(&ni_priv->interrupt_transfer_lock);
        if (retval) {
                dev_err(&usb_dev->dev, "failed to submit first interrupt urb, retval=%i\n", retval);
                return retval;
        }
        return 0;
}

static void ni_usb_cleanup_urbs(struct ni_usb_priv *ni_priv)
{
        if (ni_priv && ni_priv->bus_interface) {
                if (ni_priv->interrupt_urb)
                        usb_kill_urb(ni_priv->interrupt_urb);
                if (ni_priv->bulk_urb)
                        usb_kill_urb(ni_priv->bulk_urb);
        }
}

static int ni_usb_b_read_serial_number(struct ni_usb_priv *ni_priv)
{
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        int retval;
        u8 *out_data;
        u8 *in_data;
        static const int out_data_length = 0x20;
        static const int  in_data_length = 0x20;
        int bytes_written = 0, bytes_read = 0;
        int i = 0;
        static const int num_reads = 4;
        unsigned int results[4];
        int j;
        unsigned int serial_number;

        in_data = kmalloc(in_data_length, GFP_KERNEL);
        if (!in_data)
                return -ENOMEM;

        out_data = kmalloc(out_data_length, GFP_KERNEL);
        if (!out_data) {
                kfree(in_data);
                return -ENOMEM;
        }
        i += ni_usb_bulk_register_read_header(&out_data[i], num_reads);
        i += ni_usb_bulk_register_read(&out_data[i], NIUSB_SUBDEV_UNKNOWN3, SERIAL_NUMBER_1_REG);
        i += ni_usb_bulk_register_read(&out_data[i], NIUSB_SUBDEV_UNKNOWN3, SERIAL_NUMBER_2_REG);
        i += ni_usb_bulk_register_read(&out_data[i], NIUSB_SUBDEV_UNKNOWN3, SERIAL_NUMBER_3_REG);
        i += ni_usb_bulk_register_read(&out_data[i], NIUSB_SUBDEV_UNKNOWN3, SERIAL_NUMBER_4_REG);
        while (i % 4)
                out_data[i++] = 0x0;
        i += ni_usb_bulk_termination(&out_data[i]);
        retval = ni_usb_send_bulk_msg(ni_priv, out_data, out_data_length, &bytes_written, 1000);
        if (retval) {
                dev_err(&usb_dev->dev, "send_bulk_msg returned %i, bytes_written=%i, i=%li\n",
                        retval, bytes_written, (long)out_data_length);
                goto serial_out;
        }
        retval = ni_usb_receive_bulk_msg(ni_priv, in_data, in_data_length, &bytes_read, 1000, 0);
        if (retval) {
                dev_err(&usb_dev->dev, "receive_bulk_msg returned %i, bytes_read=%i\n",
                        retval, bytes_read);
                ni_usb_dump_raw_block(in_data, bytes_read);
                goto serial_out;
        }
        if (ARRAY_SIZE(results) < num_reads) {
                dev_err(&usb_dev->dev, "serial number eetup bug\n");
                retval = -EINVAL;
                goto serial_out;
        }
        ni_usb_parse_register_read_block(in_data, results, num_reads);
        serial_number = 0;
        for (j = 0; j < num_reads; ++j)
                serial_number |= (results[j] & 0xff) << (8 * j);
        dev_dbg(&usb_dev->dev, "board serial number is 0x%x\n", serial_number);
        retval = 0;
serial_out:
        kfree(in_data);
        kfree(out_data);
        return retval;
}

static int ni_usb_hs_wait_for_ready(struct ni_usb_priv *ni_priv)
{
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        static const int buffer_size = 0x10;
        static const int timeout = 50;
        static const int msec_sleep_duration = 100;
        int i;  int retval;
        int j;
        int unexpected = 0;
        unsigned int serial_number;
        u8 *buffer;

        buffer = kmalloc(buffer_size, GFP_KERNEL);
        if (!buffer)
                return -ENOMEM;

        retval = ni_usb_receive_control_msg(ni_priv, NI_USB_SERIAL_NUMBER_REQUEST,
                                            USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                            0x0, 0x0, buffer, buffer_size, 1000);
        if (retval < 0) {
                dev_err(&usb_dev->dev, "usb_control_msg request 0x%x returned %i\n",
                        NI_USB_SERIAL_NUMBER_REQUEST, retval);
                goto ready_out;
        }
        j = 0;
        if (buffer[j] != NI_USB_SERIAL_NUMBER_REQUEST) {
                dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x%x\n",
                        j, (int)buffer[j], NI_USB_SERIAL_NUMBER_REQUEST);
                unexpected = 1;
        }
        if (unexpected)
                ni_usb_dump_raw_block(buffer, retval);
        // NI-USB-HS+ pads the serial with 0x0 to make 16 bytes
        if (retval != 5 && retval != 16) {
                dev_err(&usb_dev->dev, "received unexpected number of bytes = %i, expected 5 or 16\n",
                        retval);
                ni_usb_dump_raw_block(buffer, retval);
        }
        serial_number = 0;
        serial_number |= buffer[++j];
        serial_number |= (buffer[++j] << 8);
        serial_number |= (buffer[++j] << 16);
        serial_number |= (buffer[++j] << 24);
        dev_dbg(&usb_dev->dev, "board serial number is 0x%x\n", serial_number);
        for (i = 0; i < timeout; ++i) {
                int ready = 0;

                retval = ni_usb_receive_control_msg(ni_priv, NI_USB_POLL_READY_REQUEST,
                                                    USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                                    0x0, 0x0, buffer, buffer_size, 100);
                if (retval < 0) {
                        dev_err(&usb_dev->dev, "usb_control_msg request 0x%x returned %i\n",
                                NI_USB_POLL_READY_REQUEST, retval);
                        goto ready_out;
                }
                j = 0;
                unexpected = 0;
                if (buffer[j] != NI_USB_POLL_READY_REQUEST) { // [0]
                        dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x%x\n",
                                j, (int)buffer[j], NI_USB_POLL_READY_REQUEST);
                        unexpected = 1;
                }
                ++j;
                if (buffer[j] != 0x1 && buffer[j] != 0x0) { // [1] HS+ sends 0x0
                        dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x1 or 0x0\n",
                                j, (int)buffer[j]);
                        unexpected = 1;
                }
                if (buffer[++j] != 0x0) { // [2]
                        dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x%x\n",
                                j, (int)buffer[j], 0x0);
                        unexpected = 1;
                }
                ++j;
                /*
                 * MC usb-488 (and sometimes NI-USB-HS?) sends 0x8 here; MC usb-488A sends 0x7 here
                 * NI-USB-HS+ sends 0x0
                 */
                if (buffer[j] != 0x1 && buffer[j] != 0x8 && buffer[j] != 0x7 && buffer[j] != 0x0) {
                        // [3]
                        dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x0, 0x1, 0x7 or 0x8\n",
                                j, (int)buffer[j]);
                        unexpected = 1;
                }
                ++j;
                // NI-USB-HS+ sends 0 here
                if (buffer[j] != 0x30 && buffer[j] != 0x0) { // [4]
                        dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x0 or 0x30\n",
                                j, (int)buffer[j]);
                        unexpected = 1;
                }
                ++j;
                // MC usb-488 (and sometimes NI-USB-HS?) and NI-USB-HS+ sends 0x0 here
                if (buffer[j] != 0x1 && buffer[j] != 0x0) { // [5]
                        dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x1 or 0x0\n",
                                j, (int)buffer[j]);
                        unexpected = 1;
                }
                if (buffer[++j] != 0x0) { // [6]
                        ready = 1;
                        // NI-USB-HS+ sends 0xf or 0x19 here
                        if (buffer[j] != 0x2 && buffer[j] != 0xe && buffer[j] != 0xf &&
                            buffer[j] != 0x16 && buffer[j] != 0x19) {
                                dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x2, 0xe, 0xf, 0x16 or 0x19\n",
                                        j, (int)buffer[j]);
                                unexpected = 1;
                        }
                }
                if (buffer[++j] != 0x0) { // [7]
                        ready = 1;
                        // MC usb-488 sends 0x5 here; MC usb-488A sends 0x6 here
                        if (buffer[j] != 0x3 && buffer[j] != 0x5 && buffer[j] != 0x6 &&
                            buffer[j] != 0x8)   {
                                dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x3 or 0x5, 0x6 or 0x08\n",
                                        j, (int)buffer[j]);
                                unexpected = 1;
                        }
                }
                ++j;
                if (buffer[j] != 0x0 && buffer[j] != 0x2) { // [8] MC usb-488 sends 0x2 here
                        dev_err(&usb_dev->dev, " unexpected data: buffer[%i]=0x%x, expected 0x0 or 0x2\n",
                                j, (int)buffer[j]);
                        unexpected = 1;
                }
                ++j;
                // MC usb-488A and NI-USB-HS sends 0x3 here; NI-USB-HS+ sends 0x30 here
                if (buffer[j] != 0x0 && buffer[j] != 0x3 && buffer[j] != 0x30) { // [9]
                        dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x0, 0x3 or 0x30\n",
                                j, (int)buffer[j]);
                        unexpected = 1;
                }
                if (buffer[++j] != 0x0) { // [10] MC usb-488 sends 0x7 here, new HS+ sends 0x59
                        ready = 1;
                        if (buffer[j] != 0x96 && buffer[j] != 0x7 && buffer[j] != 0x6e &&
                            buffer[j] != 0x59) {
                                dev_err(&usb_dev->dev, "unexpected data: buffer[%i]=0x%x, expected 0x96, 0x07, 0x6e or 0x59\n",
                                        j, (int)buffer[j]);
                                unexpected = 1;
                        }
                }
                if (unexpected)
                        ni_usb_dump_raw_block(buffer, retval);
                if (ready)
                        break;
                retval = msleep_interruptible(msec_sleep_duration);
                if (retval) {
                        retval = -ERESTARTSYS;
                        goto ready_out;
                }
        }
        retval = 0;

ready_out:
        kfree(buffer);
        dev_dbg(&usb_dev->dev, "exit retval=%d\n", retval);
        return retval;
}

/*
 * This does some extra init for HS+ models, as observed on Windows.  One of the
 * control requests causes the LED to stop blinking.
 * I'm not sure what the other 2 requests do.  None of these requests are actually required
 * for the adapter to work, maybe they do some init for the analyzer interface
 * (which we don't use).
 */
static int ni_usb_hs_plus_extra_init(struct ni_usb_priv *ni_priv)
{
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        int retval;
        u8 *buffer;
        static const int buffer_size = 16;
        int transfer_size;

        buffer = kmalloc(buffer_size, GFP_KERNEL);
        if (!buffer)
                return -ENOMEM;
        do {
                transfer_size = 16;

                retval = ni_usb_receive_control_msg(ni_priv, NI_USB_HS_PLUS_0x48_REQUEST,
                                                    USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                                    0x0, 0x0, buffer, transfer_size, 1000);
                if (retval < 0) {
                        dev_err(&usb_dev->dev, "usb_control_msg request 0x%x returned %i\n",
                                NI_USB_HS_PLUS_0x48_REQUEST, retval);
                        break;
                }
                // expected response data: 48 f3 30 00 00 00 00 00 00 00 00 00 00 00 00 00
                if (buffer[0] != NI_USB_HS_PLUS_0x48_REQUEST)
                        dev_err(&usb_dev->dev, "unexpected data: buffer[0]=0x%x, expected 0x%x\n",
                                (int)buffer[0], NI_USB_HS_PLUS_0x48_REQUEST);

                transfer_size = 2;

                retval = ni_usb_receive_control_msg(ni_priv, NI_USB_HS_PLUS_LED_REQUEST,
                                                    USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                                    0x1, 0x0, buffer, transfer_size, 1000);
                if (retval < 0) {
                        dev_err(&usb_dev->dev, "usb_control_msg request 0x%x returned %i\n",
                                NI_USB_HS_PLUS_LED_REQUEST, retval);
                        break;
                }
                // expected response data: 4b 00
                if (buffer[0] != NI_USB_HS_PLUS_LED_REQUEST)
                        dev_err(&usb_dev->dev, "unexpected data: buffer[0]=0x%x, expected 0x%x\n",
                                (int)buffer[0], NI_USB_HS_PLUS_LED_REQUEST);

                transfer_size = 9;

                retval = ni_usb_receive_control_msg(ni_priv, NI_USB_HS_PLUS_0xf8_REQUEST,
                                                    USB_DIR_IN | USB_TYPE_VENDOR |
                                                    USB_RECIP_INTERFACE,
                                                    0x0, 0x1, buffer, transfer_size, 1000);
                if (retval < 0) {
                        dev_err(&usb_dev->dev, "usb_control_msg request 0x%x returned %i\n",
                                NI_USB_HS_PLUS_0xf8_REQUEST, retval);
                        break;
                }
                // expected response data: f8 01 00 00 00 01 00 00 00
                if (buffer[0] != NI_USB_HS_PLUS_0xf8_REQUEST)
                        dev_err(&usb_dev->dev, "unexpected data: buffer[0]=0x%x, expected 0x%x\n",
                                (int)buffer[0], NI_USB_HS_PLUS_0xf8_REQUEST);
        } while (0);

        // cleanup
        kfree(buffer);
        return retval;
}

static inline int ni_usb_device_match(struct usb_interface *interface,
                                      const struct gpib_board_config *config)
{
        if (gpib_match_device_path(&interface->dev, config->device_path) == 0)
                return 0;
        return 1;
}

static int ni_usb_attach(struct gpib_board *board, const struct gpib_board_config *config)
{
        int retval;
        int i, index;
        struct ni_usb_priv *ni_priv;
        int product_id;
        struct usb_device *usb_dev;

        mutex_lock(&ni_usb_hotplug_lock);
        retval = ni_usb_allocate_private(board);
        if (retval) {
                mutex_unlock(&ni_usb_hotplug_lock);
                return retval;
        }
        ni_priv = board->private_data;
        for (i = 0; i < MAX_NUM_NI_USB_INTERFACES; i++) {
                if (ni_usb_driver_interfaces[i] &&
                    !usb_get_intfdata(ni_usb_driver_interfaces[i]) &&
                    ni_usb_device_match(ni_usb_driver_interfaces[i], config)) {
                        ni_priv->bus_interface = ni_usb_driver_interfaces[i];
                        usb_set_intfdata(ni_usb_driver_interfaces[i], board);
                        usb_dev = interface_to_usbdev(ni_priv->bus_interface);
                        index = i;
                        break;
                }
        }
        if (i == MAX_NUM_NI_USB_INTERFACES) {
                mutex_unlock(&ni_usb_hotplug_lock);
                dev_err(board->gpib_dev, "No supported adapters found, have you loaded its firmware?\n");
                return -ENODEV;
        }
        if (usb_reset_configuration(interface_to_usbdev(ni_priv->bus_interface)))
                dev_err(&usb_dev->dev, "usb_reset_configuration() failed.\n");

        product_id = le16_to_cpu(usb_dev->descriptor.idProduct);
        ni_priv->product_id = product_id;

        timer_setup(&ni_priv->bulk_timer, ni_usb_timeout_handler, 0);

        switch (product_id) {
        case USB_DEVICE_ID_NI_USB_B:
                ni_priv->bulk_out_endpoint = NIUSB_B_BULK_OUT_ENDPOINT;
                ni_priv->bulk_in_endpoint = NIUSB_B_BULK_IN_ENDPOINT;
                ni_priv->interrupt_in_endpoint = NIUSB_B_INTERRUPT_IN_ENDPOINT;
                ni_usb_b_read_serial_number(ni_priv);
                break;
        case USB_DEVICE_ID_NI_USB_HS:
        case USB_DEVICE_ID_MC_USB_488:
        case USB_DEVICE_ID_KUSB_488A:
                ni_priv->bulk_out_endpoint = NIUSB_HS_BULK_OUT_ENDPOINT;
                ni_priv->bulk_in_endpoint = NIUSB_HS_BULK_IN_ENDPOINT;
                ni_priv->interrupt_in_endpoint = NIUSB_HS_INTERRUPT_IN_ENDPOINT;
                retval = ni_usb_hs_wait_for_ready(ni_priv);
                if (retval < 0) {
                        mutex_unlock(&ni_usb_hotplug_lock);
                        return retval;
                }
                break;
        case USB_DEVICE_ID_NI_USB_HS_PLUS:
                ni_priv->bulk_out_endpoint = NIUSB_HS_PLUS_BULK_OUT_ENDPOINT;
                ni_priv->bulk_in_endpoint = NIUSB_HS_PLUS_BULK_IN_ENDPOINT;
                ni_priv->interrupt_in_endpoint = NIUSB_HS_PLUS_INTERRUPT_IN_ENDPOINT;
                retval = ni_usb_hs_wait_for_ready(ni_priv);
                if (retval < 0) {
                        mutex_unlock(&ni_usb_hotplug_lock);
                        return retval;
                }
                retval = ni_usb_hs_plus_extra_init(ni_priv);
                if (retval < 0) {
                        mutex_unlock(&ni_usb_hotplug_lock);
                        return retval;
                }
                break;
        default:
                mutex_unlock(&ni_usb_hotplug_lock);
                dev_err(&usb_dev->dev, "\tDriver bug: unknown endpoints for usb device id %x\n",
                        product_id);
                return -EINVAL;
        }

        retval = ni_usb_setup_urbs(board);
        if (retval < 0) {
                mutex_unlock(&ni_usb_hotplug_lock);
                return retval;
        }
        retval = ni_usb_set_interrupt_monitor(board, 0);
        if (retval < 0) {
                mutex_unlock(&ni_usb_hotplug_lock);
                return retval;
        }

        board->t1_nano_sec = 500;

        retval = ni_usb_init(board);
        if (retval < 0) {
                mutex_unlock(&ni_usb_hotplug_lock);
                return retval;
        }
        retval = ni_usb_set_interrupt_monitor(board, ni_usb_ibsta_monitor_mask);
        if (retval < 0)         {
                mutex_unlock(&ni_usb_hotplug_lock);
                return retval;
        }

        mutex_unlock(&ni_usb_hotplug_lock);
        dev_info(&usb_dev->dev,
                 "bus %d dev num %d attached to gpib%d, intf %i\n",
                 usb_dev->bus->busnum, usb_dev->devnum, board->minor, index);
        return retval;
}

static int ni_usb_shutdown_hardware(struct ni_usb_priv *ni_priv)
{
        struct usb_device *usb_dev = interface_to_usbdev(ni_priv->bus_interface);
        int retval;
        struct ni_usb_register writes[2];
        static const int writes_length = ARRAY_SIZE(writes);
        unsigned int ibsta;

        writes[0].device = NIUSB_SUBDEV_TNT4882;
        writes[0].address = nec7210_to_tnt4882_offset(AUXMR);
        writes[0].value = AUX_CR;
        writes[1].device = NIUSB_SUBDEV_UNKNOWN3;
        writes[1].address = 0x10;
        writes[1].value = 0x0;
        retval = ni_usb_write_registers(ni_priv, writes, writes_length, &ibsta);
        if (retval) {
                dev_err(&usb_dev->dev, "register write failed, retval=%i\n", retval);
                return retval;
        }
        return 0;
}

static void ni_usb_detach(struct gpib_board *board)
{
        struct ni_usb_priv *ni_priv;

        mutex_lock(&ni_usb_hotplug_lock);
        /*
         * under windows, software unplug does chip_reset nec7210 aux command,
         * then writes 0x0 to address 0x10 of device 3
         */
        ni_priv = board->private_data;
        if (ni_priv) {
                if (ni_priv->bus_interface) {
                        ni_usb_set_interrupt_monitor(board, 0);
                        ni_usb_shutdown_hardware(ni_priv);
                        usb_set_intfdata(ni_priv->bus_interface, NULL);
                }
                mutex_lock(&ni_priv->bulk_transfer_lock);
                mutex_lock(&ni_priv->control_transfer_lock);
                mutex_lock(&ni_priv->interrupt_transfer_lock);
                ni_usb_cleanup_urbs(ni_priv);
                ni_usb_free_private(ni_priv);
        }
        mutex_unlock(&ni_usb_hotplug_lock);
}

static struct gpib_interface ni_usb_gpib_interface = {
        .name = "ni_usb_b",
        .attach = ni_usb_attach,
        .detach = ni_usb_detach,
        .read = ni_usb_read,
        .write = ni_usb_write,
        .command = ni_usb_command,
        .take_control = ni_usb_take_control,
        .go_to_standby = ni_usb_go_to_standby,
        .request_system_control = ni_usb_request_system_control,
        .interface_clear = ni_usb_interface_clear,
        .remote_enable = ni_usb_remote_enable,
        .enable_eos = ni_usb_enable_eos,
        .disable_eos = ni_usb_disable_eos,
        .parallel_poll = ni_usb_parallel_poll,
        .parallel_poll_configure = ni_usb_parallel_poll_configure,
        .parallel_poll_response = ni_usb_parallel_poll_response,
        .local_parallel_poll_mode = NULL, // XXX
        .line_status = ni_usb_line_status,
        .update_status = ni_usb_update_status,
        .primary_address = ni_usb_primary_address,
        .secondary_address = ni_usb_secondary_address,
        .serial_poll_response = ni_usb_serial_poll_response,
        .serial_poll_status = ni_usb_serial_poll_status,
        .t1_delay = ni_usb_t1_delay,
        .return_to_local = ni_usb_return_to_local,
        .skip_check_for_command_acceptors = 1
};

// Table with the USB-devices: just now only testing IDs
static struct usb_device_id ni_usb_driver_device_table[] = {
        {USB_DEVICE(USB_VENDOR_ID_NI, USB_DEVICE_ID_NI_USB_B)},
        {USB_DEVICE(USB_VENDOR_ID_NI, USB_DEVICE_ID_NI_USB_HS)},
        // gpib-usb-hs+ has a second interface for the analyzer, which we ignore
        {USB_DEVICE_INTERFACE_NUMBER(USB_VENDOR_ID_NI, USB_DEVICE_ID_NI_USB_HS_PLUS, 0)},
        {USB_DEVICE(USB_VENDOR_ID_NI, USB_DEVICE_ID_KUSB_488A)},
        {USB_DEVICE(USB_VENDOR_ID_NI, USB_DEVICE_ID_MC_USB_488)},
        {} /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, ni_usb_driver_device_table);

static int ni_usb_driver_probe(struct usb_interface *interface, const struct usb_device_id *id)
{
        struct usb_device *usb_dev = interface_to_usbdev(interface);
        int i;
        char *path;
        static const int path_length = 1024;

        mutex_lock(&ni_usb_hotplug_lock);
        usb_get_dev(usb_dev);
        for (i = 0; i < MAX_NUM_NI_USB_INTERFACES; i++) {
                if (!ni_usb_driver_interfaces[i]) {
                        ni_usb_driver_interfaces[i] = interface;
                        usb_set_intfdata(interface, NULL);
                        break;
                }
        }
        if (i == MAX_NUM_NI_USB_INTERFACES) {
                usb_put_dev(usb_dev);
                mutex_unlock(&ni_usb_hotplug_lock);
                dev_err(&usb_dev->dev, "ni_usb_driver_interfaces[] full\n");
                return -1;
        }
        path = kmalloc(path_length, GFP_KERNEL);
        if (!path) {
                usb_put_dev(usb_dev);
                mutex_unlock(&ni_usb_hotplug_lock);
                return -ENOMEM;
        }
        usb_make_path(usb_dev, path, path_length);
        dev_info(&usb_dev->dev, "probe succeeded for path: %s\n", path);
        kfree(path);
        mutex_unlock(&ni_usb_hotplug_lock);
        return 0;
}

static void ni_usb_driver_disconnect(struct usb_interface *interface)
{
        struct usb_device *usb_dev = interface_to_usbdev(interface);
        int i;

        mutex_lock(&ni_usb_hotplug_lock);
        for (i = 0; i < MAX_NUM_NI_USB_INTERFACES; i++) {
                if (ni_usb_driver_interfaces[i] == interface)   {
                        struct gpib_board *board = usb_get_intfdata(interface);

                        if (board) {
                                struct ni_usb_priv *ni_priv = board->private_data;

                                if (ni_priv) {
                                        mutex_lock(&ni_priv->bulk_transfer_lock);
                                        mutex_lock(&ni_priv->control_transfer_lock);
                                        mutex_lock(&ni_priv->interrupt_transfer_lock);
                                        ni_usb_cleanup_urbs(ni_priv);
                                        ni_priv->bus_interface = NULL;
                                        mutex_unlock(&ni_priv->interrupt_transfer_lock);
                                        mutex_unlock(&ni_priv->control_transfer_lock);
                                        mutex_unlock(&ni_priv->bulk_transfer_lock);
                                }
                        }
                        ni_usb_driver_interfaces[i] = NULL;
                        break;
                }
        }
        if (i == MAX_NUM_NI_USB_INTERFACES)
                dev_err(&usb_dev->dev, "unable to find interface  bug?\n");
        usb_put_dev(usb_dev);
        mutex_unlock(&ni_usb_hotplug_lock);
}

static int ni_usb_driver_suspend(struct usb_interface *interface, pm_message_t message)
{
        struct usb_device *usb_dev = interface_to_usbdev(interface);
        struct gpib_board *board;
        int i, retval;

        mutex_lock(&ni_usb_hotplug_lock);

        for (i = 0; i < MAX_NUM_NI_USB_INTERFACES; i++) {
                if (ni_usb_driver_interfaces[i] == interface) {
                        board = usb_get_intfdata(interface);
                        if (board)
                                break;
                }
        }
        if (i == MAX_NUM_NI_USB_INTERFACES) {
                mutex_unlock(&ni_usb_hotplug_lock);
                return 0;
        }

        struct ni_usb_priv *ni_priv = board->private_data;

        if (ni_priv) {
                ni_usb_set_interrupt_monitor(board, 0);
                retval = ni_usb_shutdown_hardware(ni_priv);
                if (retval) {
                        mutex_unlock(&ni_usb_hotplug_lock);
                        return retval;
                }
                if (ni_priv->interrupt_urb) {
                        mutex_lock(&ni_priv->interrupt_transfer_lock);
                        ni_usb_cleanup_urbs(ni_priv);
                        mutex_unlock(&ni_priv->interrupt_transfer_lock);
                }
                dev_dbg(&usb_dev->dev,
                        "bus %d dev num %d gpib%d, interface %i suspended\n",
                        usb_dev->bus->busnum, usb_dev->devnum, board->minor, i);
        }

        mutex_unlock(&ni_usb_hotplug_lock);
        return 0;
}

static int ni_usb_driver_resume(struct usb_interface *interface)
{
        struct usb_device *usb_dev = interface_to_usbdev(interface);

        struct gpib_board *board;
        int i, retval;

        mutex_lock(&ni_usb_hotplug_lock);

        for (i = 0; i < MAX_NUM_NI_USB_INTERFACES; i++) {
                if (ni_usb_driver_interfaces[i] == interface) {
                        board = usb_get_intfdata(interface);
                        if (board)
                                break;
                }
        }
        if (i == MAX_NUM_NI_USB_INTERFACES) {
                mutex_unlock(&ni_usb_hotplug_lock);
                return 0;
        }

        struct ni_usb_priv *ni_priv = board->private_data;

        if (ni_priv) {
                if (ni_priv->interrupt_urb) {
                        mutex_lock(&ni_priv->interrupt_transfer_lock);
                        retval = usb_submit_urb(ni_priv->interrupt_urb, GFP_KERNEL);
                        if (retval) {
                                dev_err(&usb_dev->dev, "resume failed to resubmit interrupt urb, retval=%i\n",
                                        retval);
                                mutex_unlock(&ni_priv->interrupt_transfer_lock);
                                mutex_unlock(&ni_usb_hotplug_lock);
                                return retval;
                        }
                        mutex_unlock(&ni_priv->interrupt_transfer_lock);
                } else {
                        dev_err(&usb_dev->dev, "bug! resume int urb not set up\n");
                        mutex_unlock(&ni_usb_hotplug_lock);
                        return -EINVAL;
                }

                switch (ni_priv->product_id) {
                case USB_DEVICE_ID_NI_USB_B:
                        ni_usb_b_read_serial_number(ni_priv);
                        break;
                case USB_DEVICE_ID_NI_USB_HS:
                case USB_DEVICE_ID_MC_USB_488:
                case USB_DEVICE_ID_KUSB_488A:
                        retval = ni_usb_hs_wait_for_ready(ni_priv);
                        if (retval < 0) {
                                mutex_unlock(&ni_usb_hotplug_lock);
                                return retval;
                        }
                        break;
                case USB_DEVICE_ID_NI_USB_HS_PLUS:
                        retval = ni_usb_hs_wait_for_ready(ni_priv);
                        if (retval < 0) {
                                mutex_unlock(&ni_usb_hotplug_lock);
                                return retval;
                        }
                        retval = ni_usb_hs_plus_extra_init(ni_priv);
                        if (retval < 0) {
                                mutex_unlock(&ni_usb_hotplug_lock);
                                return retval;
                        }
                        break;
                default:
                        mutex_unlock(&ni_usb_hotplug_lock);
                        dev_err(&usb_dev->dev, "\tDriver bug: unknown endpoints for usb device id\n");
                        return -EINVAL;
                }

                retval = ni_usb_set_interrupt_monitor(board, 0);
                if (retval < 0) {
                        mutex_unlock(&ni_usb_hotplug_lock);
                        return retval;
                }

                retval = ni_usb_init(board);
                if (retval < 0) {
                        mutex_unlock(&ni_usb_hotplug_lock);
                        return retval;
                }
                retval = ni_usb_set_interrupt_monitor(board, ni_usb_ibsta_monitor_mask);
                if (retval < 0)         {
                        mutex_unlock(&ni_usb_hotplug_lock);
                        return retval;
                }
                if (board->master)
                        ni_usb_interface_clear(board, 1); // this is a pulsed action
                if (ni_priv->ren_state)
                        ni_usb_remote_enable(board, 1);

                dev_dbg(&usb_dev->dev,
                        "bus %d dev num %d gpib%d, interface %i resumed\n",
                        usb_dev->bus->busnum, usb_dev->devnum, board->minor, i);
        }

        mutex_unlock(&ni_usb_hotplug_lock);
        return 0;
}

static struct usb_driver ni_usb_bus_driver = {
        .name = DRV_NAME,
        .probe = ni_usb_driver_probe,
        .disconnect = ni_usb_driver_disconnect,
        .suspend = ni_usb_driver_suspend,
        .resume = ni_usb_driver_resume,
        .id_table = ni_usb_driver_device_table,
};

static int __init ni_usb_init_module(void)
{
        int i;
        int ret;

        for (i = 0; i < MAX_NUM_NI_USB_INTERFACES; i++)
                ni_usb_driver_interfaces[i] = NULL;

        ret = usb_register(&ni_usb_bus_driver);
        if (ret) {
                pr_err("usb_register failed: error = %d\n", ret);
                return ret;
        }

        ret = gpib_register_driver(&ni_usb_gpib_interface, THIS_MODULE);
        if (ret) {
                pr_err("gpib_register_driver failed: error = %d\n", ret);
                return ret;
        }

        return 0;
}

static void __exit ni_usb_exit_module(void)
{
        gpib_unregister_driver(&ni_usb_gpib_interface);
        usb_deregister(&ni_usb_bus_driver);
}

module_init(ni_usb_init_module);
module_exit(ni_usb_exit_module);