--- /dev/null
+/**
+ * drivers/usb/class/usbtmc.c - USB Test & Measurment class driver
+ *
+ * Copyright (C) 2007 Stefan Kopp, Gechingen, Germany
+ * Copyright (C) 2008 Novell, Inc.
+ * Copyright (C) 2008 Greg Kroah-Hartman <gregkh@suse.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * The GNU General Public License is available at
+ * http://www.gnu.org/copyleft/gpl.html.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/kref.h>
+#include <linux/mutex.h>
+#include <linux/usb.h>
+#include <linux/usb/tmc.h>
+
+
+#define USBTMC_MINOR_BASE      176
+
+/*
+ * Size of driver internal IO buffer. Must be multiple of 4 and at least as
+ * large as wMaxPacketSize (which is usually 512 bytes).
+ */
+#define USBTMC_SIZE_IOBUFFER   2048
+
+/* Default USB timeout (in milliseconds) */
+#define USBTMC_TIMEOUT         10
+
+/*
+ * Maximum number of read cycles to empty bulk in endpoint during CLEAR and
+ * ABORT_BULK_IN requests. Ends the loop if (for whatever reason) a short
+ * packet is never read.
+ */
+#define USBTMC_MAX_READS_TO_CLEAR_BULK_IN      100
+
+static struct usb_device_id usbtmc_devices[] = {
+       { USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, 3, 0), },
+       { 0, } /* terminating entry */
+};
+
+/*
+ * This structure is the capabilities for the device
+ * See section 4.2.1.8 of the USBTMC specification for details.
+ */
+struct usbtmc_dev_capabilities {
+       __u8 interface_capabilities;
+       __u8 device_capabilities;
+       __u8 usb488_interface_capabilities;
+       __u8 usb488_device_capabilities;
+};
+
+/* This structure holds private data for each USBTMC device. One copy is
+ * allocated for each USBTMC device in the driver's probe function.
+ */
+struct usbtmc_device_data {
+       const struct usb_device_id *id;
+       struct usb_device *usb_dev;
+       struct usb_interface *intf;
+
+       unsigned int bulk_in;
+       unsigned int bulk_out;
+
+       u8 bTag;
+       u8 bTag_last_write;     /* needed for abort */
+       u8 bTag_last_read;      /* needed for abort */
+
+       /* attributes from the USB TMC spec for this device */
+       u8 TermChar;
+       bool TermCharEnabled;
+       bool auto_abort;
+
+       struct usbtmc_dev_capabilities  capabilities;
+       struct kref kref;
+       struct mutex io_mutex;  /* only one i/o function running at a time */
+};
+#define to_usbtmc_data(d) container_of(d, struct usbtmc_device_data, kref)
+
+/* Forward declarations */
+static struct usb_driver usbtmc_driver;
+
+static void usbtmc_delete(struct kref *kref)
+{
+       struct usbtmc_device_data *data = to_usbtmc_data(kref);
+
+       usb_put_dev(data->usb_dev);
+       kfree(data);
+}
+
+static int usbtmc_open(struct inode *inode, struct file *filp)
+{
+       struct usb_interface *intf;
+       struct usbtmc_device_data *data;
+       int retval = -ENODEV;
+
+       intf = usb_find_interface(&usbtmc_driver, iminor(inode));
+       if (!intf) {
+               printk(KERN_ERR KBUILD_MODNAME
+                      ": can not find device for minor %d", iminor(inode));
+               goto exit;
+       }
+
+       data = usb_get_intfdata(intf);
+       kref_get(&data->kref);
+
+       /* Store pointer in file structure's private data field */
+       filp->private_data = data;
+
+exit:
+       return retval;
+}
+
+static int usbtmc_release(struct inode *inode, struct file *file)
+{
+       struct usbtmc_device_data *data = file->private_data;
+
+       kref_put(&data->kref, usbtmc_delete);
+       return 0;
+}
+
+static int usbtmc_ioctl_abort_bulk_in(struct usbtmc_device_data *data)
+{
+       char *buffer;
+       struct device *dev;
+       int rv;
+       int n;
+       int actual;
+       struct usb_host_interface *current_setting;
+       int max_size;
+
+       dev = &data->intf->dev;
+       buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       rv = usb_control_msg(data->usb_dev,
+                            usb_rcvctrlpipe(data->usb_dev, 0),
+                            USBTMC_REQUEST_INITIATE_ABORT_BULK_IN,
+                            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
+                            data->bTag_last_read, data->bulk_in,
+                            buffer, 2, USBTMC_TIMEOUT);
+
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+
+       dev_dbg(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
+
+       if (buffer[0] == USBTMC_STATUS_FAILED) {
+               rv = 0;
+               goto exit;
+       }
+
+       if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+               dev_err(dev, "INITIATE_ABORT_BULK_IN returned %x\n",
+                       buffer[0]);
+               rv = -EPERM;
+               goto exit;
+       }
+
+       max_size = 0;
+       current_setting = data->intf->cur_altsetting;
+       for (n = 0; n < current_setting->desc.bNumEndpoints; n++)
+               if (current_setting->endpoint[n].desc.bEndpointAddress ==
+                       data->bulk_in)
+                       max_size = le16_to_cpu(current_setting->endpoint[n].
+                                               desc.wMaxPacketSize);
+
+       if (max_size == 0) {
+               dev_err(dev, "Couldn't get wMaxPacketSize\n");
+               rv = -EPERM;
+               goto exit;
+       }
+
+       dev_dbg(&data->intf->dev, "wMaxPacketSize is %d\n", max_size);
+
+       n = 0;
+
+       do {
+               dev_dbg(dev, "Reading from bulk in EP\n");
+
+               rv = usb_bulk_msg(data->usb_dev,
+                                 usb_rcvbulkpipe(data->usb_dev,
+                                                 data->bulk_in),
+                                 buffer, USBTMC_SIZE_IOBUFFER,
+                                 &actual, USBTMC_TIMEOUT);
+
+               n++;
+
+               if (rv < 0) {
+                       dev_err(dev, "usb_bulk_msg returned %d\n", rv);
+                       goto exit;
+               }
+       } while ((actual == max_size) &&
+                (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
+
+       if (actual == max_size) {
+               dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
+                       USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
+               rv = -EPERM;
+               goto exit;
+       }
+
+       n = 0;
+
+usbtmc_abort_bulk_in_status:
+       rv = usb_control_msg(data->usb_dev,
+                            usb_rcvctrlpipe(data->usb_dev, 0),
+                            USBTMC_REQUEST_CHECK_ABORT_BULK_IN_STATUS,
+                            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
+                            0, data->bulk_in, buffer, 0x08,
+                            USBTMC_TIMEOUT);
+
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+
+       dev_dbg(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
+
+       if (buffer[0] == USBTMC_STATUS_SUCCESS) {
+               rv = 0;
+               goto exit;
+       }
+
+       if (buffer[0] != USBTMC_STATUS_PENDING) {
+               dev_err(dev, "INITIATE_ABORT_BULK_IN returned %x\n", buffer[0]);
+               rv = -EPERM;
+               goto exit;
+       }
+
+       if (buffer[1] == 1)
+               do {
+                       dev_dbg(dev, "Reading from bulk in EP\n");
+
+                       rv = usb_bulk_msg(data->usb_dev,
+                                         usb_rcvbulkpipe(data->usb_dev,
+                                                         data->bulk_in),
+                                         buffer, USBTMC_SIZE_IOBUFFER,
+                                         &actual, USBTMC_TIMEOUT);
+
+                       n++;
+
+                       if (rv < 0) {
+                               dev_err(dev, "usb_bulk_msg returned %d\n", rv);
+                               goto exit;
+                       }
+               } while ((actual = max_size) &&
+                        (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
+
+       if (actual == max_size) {
+               dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
+                       USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
+               rv = -EPERM;
+               goto exit;
+       }
+
+       goto usbtmc_abort_bulk_in_status;
+
+exit:
+       kfree(buffer);
+       return rv;
+
+}
+
+static int usbtmc_ioctl_abort_bulk_out(struct usbtmc_device_data *data)
+{
+       struct device *dev;
+       u8 *buffer;
+       int rv;
+       int n;
+
+       dev = &data->intf->dev;
+
+       buffer = kmalloc(8, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       rv = usb_control_msg(data->usb_dev,
+                            usb_rcvctrlpipe(data->usb_dev, 0),
+                            USBTMC_REQUEST_INITIATE_ABORT_BULK_OUT,
+                            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
+                            data->bTag_last_write, data->bulk_out,
+                            buffer, 2, USBTMC_TIMEOUT);
+
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+
+       dev_dbg(dev, "INITIATE_ABORT_BULK_OUT returned %x\n", buffer[0]);
+
+       if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+               dev_err(dev, "INITIATE_ABORT_BULK_OUT returned %x\n",
+                       buffer[0]);
+               rv = -EPERM;
+               goto exit;
+       }
+
+       n = 0;
+
+usbtmc_abort_bulk_out_check_status:
+       rv = usb_control_msg(data->usb_dev,
+                            usb_rcvctrlpipe(data->usb_dev, 0),
+                            USBTMC_REQUEST_CHECK_ABORT_BULK_OUT_STATUS,
+                            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
+                            0, data->bulk_out, buffer, 0x08,
+                            USBTMC_TIMEOUT);
+       n++;
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+
+       dev_dbg(dev, "CHECK_ABORT_BULK_OUT returned %x\n", buffer[0]);
+
+       if (buffer[0] == USBTMC_STATUS_SUCCESS)
+               goto usbtmc_abort_bulk_out_clear_halt;
+
+       if ((buffer[0] == USBTMC_STATUS_PENDING) &&
+           (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN))
+               goto usbtmc_abort_bulk_out_check_status;
+
+       rv = -EPERM;
+       goto exit;
+
+usbtmc_abort_bulk_out_clear_halt:
+       rv = usb_control_msg(data->usb_dev,
+                            usb_sndctrlpipe(data->usb_dev, 0),
+                            USB_REQ_CLEAR_FEATURE,
+                            USB_DIR_OUT | USB_TYPE_STANDARD |
+                            USB_RECIP_ENDPOINT,
+                            USB_ENDPOINT_HALT, data->bulk_out, buffer,
+                            0, USBTMC_TIMEOUT);
+
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+       rv = 0;
+
+exit:
+       kfree(buffer);
+       return rv;
+}
+
+static ssize_t usbtmc_read(struct file *filp, char __user *buf,
+                          size_t count, loff_t *f_pos)
+{
+       struct usbtmc_device_data *data;
+       struct device *dev;
+       unsigned long int n_characters;
+       u8 *buffer;
+       int actual;
+       int done;
+       int remaining;
+       int retval;
+       int this_part;
+
+       /* Get pointer to private data structure */
+       data = filp->private_data;
+       dev = &data->intf->dev;
+
+       buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       mutex_lock(&data->io_mutex);
+
+       remaining = count;
+       done = 0;
+
+       while (remaining > 0) {
+               if (remaining > USBTMC_SIZE_IOBUFFER - 12 - 3)
+                       this_part = USBTMC_SIZE_IOBUFFER - 12 - 3;
+               else
+                       this_part = remaining;
+
+               /* Setup IO buffer for DEV_DEP_MSG_IN message
+                * Refer to class specs for details
+                */
+               buffer[0] = 2;
+               buffer[1] = data->bTag;
+               buffer[2] = ~(data->bTag);
+               buffer[3] = 0; /* Reserved */
+               buffer[4] = (this_part - 12 - 3) & 255;
+               buffer[5] = ((this_part - 12 - 3) >> 8) & 255;
+               buffer[6] = ((this_part - 12 - 3) >> 16) & 255;
+               buffer[7] = ((this_part - 12 - 3) >> 24) & 255;
+               buffer[8] = data->TermCharEnabled * 2;
+               /* Use term character? */
+               buffer[9] = data->TermChar;
+               buffer[10] = 0; /* Reserved */
+               buffer[11] = 0; /* Reserved */
+
+               /* Send bulk URB */
+               retval = usb_bulk_msg(data->usb_dev,
+                                     usb_sndbulkpipe(data->usb_dev,
+                                                     data->bulk_out),
+                                     buffer, 12, &actual, USBTMC_TIMEOUT);
+
+               /* Store bTag (in case we need to abort) */
+               data->bTag_last_write = data->bTag;
+
+               /* Increment bTag -- and increment again if zero */
+               data->bTag++;
+               if (!data->bTag)
+                       (data->bTag)++;
+
+               if (retval < 0) {
+                       dev_err(dev, "usb_bulk_msg returned %d\n", retval);
+                       if (data->auto_abort)
+                               usbtmc_ioctl_abort_bulk_out(data);
+                       goto exit;
+               }
+
+               /* Send bulk URB */
+               retval = usb_bulk_msg(data->usb_dev,
+                                     usb_rcvbulkpipe(data->usb_dev,
+                                                     data->bulk_in),
+                                     buffer, USBTMC_SIZE_IOBUFFER, &actual,
+                                     USBTMC_TIMEOUT);
+
+               /* Store bTag (in case we need to abort) */
+               data->bTag_last_read = data->bTag;
+
+               if (retval < 0) {
+                       dev_err(dev, "Unable to read data, error %d\n", retval);
+                       if (data->auto_abort)
+                               usbtmc_ioctl_abort_bulk_in(data);
+                       goto exit;
+               }
+
+               /* How many characters did the instrument send? */
+               n_characters = buffer[4] +
+                              (buffer[5] << 8) +
+                              (buffer[6] << 16) +
+                              (buffer[7] << 24);
+
+               /* Copy buffer to user space */
+               if (copy_to_user(buf + done, &buffer[12], n_characters)) {
+                       /* There must have been an addressing problem */
+                       retval = -EFAULT;
+                       goto exit;
+               }
+
+               done += n_characters;
+               if (n_characters < USBTMC_SIZE_IOBUFFER)
+                       remaining = 0;
+       }
+
+       /* Update file position value */
+       *f_pos = *f_pos + done;
+       retval = done;
+
+exit:
+       mutex_unlock(&data->io_mutex);
+       kfree(buffer);
+       return retval;
+}
+
+static ssize_t usbtmc_write(struct file *filp, const char __user *buf,
+                           size_t count, loff_t *f_pos)
+{
+       struct usbtmc_device_data *data;
+       u8 *buffer;
+       int retval;
+       int actual;
+       unsigned long int n_bytes;
+       int n;
+       int remaining;
+       int done;
+       int this_part;
+
+       data = filp->private_data;
+
+       buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       mutex_lock(&data->io_mutex);
+
+       remaining = count;
+       done = 0;
+
+       while (remaining > 0) {
+               if (remaining > USBTMC_SIZE_IOBUFFER - 12) {
+                       this_part = USBTMC_SIZE_IOBUFFER - 12;
+                       buffer[8] = 0;
+               } else {
+                       this_part = remaining;
+                       buffer[8] = 1;
+               }
+
+               /* Setup IO buffer for DEV_DEP_MSG_OUT message */
+               buffer[0] = 1;
+               buffer[1] = data->bTag;
+               buffer[2] = ~(data->bTag);
+               buffer[3] = 0; /* Reserved */
+               buffer[4] = this_part & 255;
+               buffer[5] = (this_part >> 8) & 255;
+               buffer[6] = (this_part >> 16) & 255;
+               buffer[7] = (this_part >> 24) & 255;
+               /* buffer[8] is set above... */
+               buffer[9] = 0; /* Reserved */
+               buffer[10] = 0; /* Reserved */
+               buffer[11] = 0; /* Reserved */
+
+               if (copy_from_user(&buffer[12], buf + done, this_part)) {
+                       retval = -EFAULT;
+                       goto exit;
+               }
+
+               n_bytes = 12 + this_part;
+               if (this_part % 4)
+                       n_bytes += 4 - this_part % 4;
+                       for (n = 12 + this_part; n < n_bytes; n++)
+                               buffer[n] = 0;
+
+               retval = usb_bulk_msg(data->usb_dev,
+                                     usb_sndbulkpipe(data->usb_dev,
+                                                     data->bulk_out),
+                                     buffer, n_bytes, &actual, USBTMC_TIMEOUT);
+
+               data->bTag_last_write = data->bTag;
+               data->bTag++;
+
+               if (!data->bTag)
+                       data->bTag++;
+
+               if (retval < 0) {
+                       dev_err(&data->intf->dev,
+                               "Unable to send data, error %d\n", retval);
+                       if (data->auto_abort)
+                               usbtmc_ioctl_abort_bulk_out(data);
+                       goto exit;
+               }
+
+               remaining -= this_part;
+               done += this_part;
+       }
+
+       retval = count;
+exit:
+       mutex_unlock(&data->io_mutex);
+       kfree(buffer);
+       return retval;
+}
+
+static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)
+{
+       struct usb_host_interface *current_setting;
+       struct usb_endpoint_descriptor *desc;
+       struct device *dev;
+       u8 *buffer;
+       int rv;
+       int n;
+       int actual;
+       int max_size;
+
+       dev = &data->intf->dev;
+
+       dev_dbg(dev, "Sending INITIATE_CLEAR request\n");
+
+       buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       rv = usb_control_msg(data->usb_dev,
+                            usb_rcvctrlpipe(data->usb_dev, 0),
+                            USBTMC_REQUEST_INITIATE_CLEAR,
+                            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+                            0, 0, buffer, 1, USBTMC_TIMEOUT);
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+
+       dev_dbg(dev, "INITIATE_CLEAR returned %x\n", buffer[0]);
+
+       if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+               dev_err(dev, "INITIATE_CLEAR returned %x\n", buffer[0]);
+               rv = -EPERM;
+               goto exit;
+       }
+
+       max_size = 0;
+       current_setting = data->intf->cur_altsetting;
+       for (n = 0; n < current_setting->desc.bNumEndpoints; n++) {
+               desc = ¤t_setting->endpoint[n].desc;
+               if (desc->bEndpointAddress == data->bulk_in)
+                       max_size = le16_to_cpu(desc->wMaxPacketSize);
+       }
+
+       if (max_size == 0) {
+               dev_err(dev, "Couldn't get wMaxPacketSize\n");
+               rv = -EPERM;
+               goto exit;
+       }
+
+       dev_dbg(dev, "wMaxPacketSize is %d\n", max_size);
+
+       n = 0;
+
+usbtmc_clear_check_status:
+
+       dev_dbg(dev, "Sending CHECK_CLEAR_STATUS request\n");
+
+       rv = usb_control_msg(data->usb_dev,
+                            usb_rcvctrlpipe(data->usb_dev, 0),
+                            USBTMC_REQUEST_CHECK_CLEAR_STATUS,
+                            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+                            0, 0, buffer, 2, USBTMC_TIMEOUT);
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+
+       dev_dbg(dev, "CHECK_CLEAR_STATUS returned %x\n", buffer[0]);
+
+       if (buffer[0] == USBTMC_STATUS_SUCCESS)
+               goto usbtmc_clear_bulk_out_halt;
+
+       if (buffer[0] != USBTMC_STATUS_PENDING) {
+               dev_err(dev, "CHECK_CLEAR_STATUS returned %x\n", buffer[0]);
+               rv = -EPERM;
+               goto exit;
+       }
+
+       if (buffer[1] == 1)
+               do {
+                       dev_dbg(dev, "Reading from bulk in EP\n");
+
+                       rv = usb_bulk_msg(data->usb_dev,
+                                         usb_rcvbulkpipe(data->usb_dev,
+                                                         data->bulk_in),
+                                         buffer, USBTMC_SIZE_IOBUFFER,
+                                         &actual, USBTMC_TIMEOUT);
+                       n++;
+
+                       if (rv < 0) {
+                               dev_err(dev, "usb_control_msg returned %d\n",
+                                       rv);
+                               goto exit;
+                       }
+               } while ((actual == max_size) &&
+                         (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
+
+       if (actual == max_size) {
+               dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
+                       USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
+               rv = -EPERM;
+               goto exit;
+       }
+
+       goto usbtmc_clear_check_status;
+
+usbtmc_clear_bulk_out_halt:
+
+       rv = usb_control_msg(data->usb_dev,
+                            usb_sndctrlpipe(data->usb_dev, 0),
+                            USB_REQ_CLEAR_FEATURE,
+                            USB_DIR_OUT | USB_TYPE_STANDARD |
+                            USB_RECIP_ENDPOINT,
+                            USB_ENDPOINT_HALT,
+                            data->bulk_out, buffer, 0,
+                            USBTMC_TIMEOUT);
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+       rv = 0;
+
+exit:
+       kfree(buffer);
+       return rv;
+}
+
+static int usbtmc_ioctl_clear_out_halt(struct usbtmc_device_data *data)
+{
+       u8 *buffer;
+       int rv;
+
+       buffer = kmalloc(2, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       rv = usb_control_msg(data->usb_dev,
+                            usb_sndctrlpipe(data->usb_dev, 0),
+                            USB_REQ_CLEAR_FEATURE,
+                            USB_DIR_OUT | USB_TYPE_STANDARD |
+                            USB_RECIP_ENDPOINT,
+                            USB_ENDPOINT_HALT, data->bulk_out,
+                            buffer, 0, USBTMC_TIMEOUT);
+
+       if (rv < 0) {
+               dev_err(&data->usb_dev->dev, "usb_control_msg returned %d\n",
+                       rv);
+               goto exit;
+       }
+       rv = 0;
+
+exit:
+       kfree(buffer);
+       return rv;
+}
+
+static int usbtmc_ioctl_clear_in_halt(struct usbtmc_device_data *data)
+{
+       u8 *buffer;
+       int rv;
+
+       buffer = kmalloc(2, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       rv = usb_control_msg(data->usb_dev, usb_sndctrlpipe(data->usb_dev, 0),
+                            USB_REQ_CLEAR_FEATURE,
+                            USB_DIR_OUT | USB_TYPE_STANDARD |
+                            USB_RECIP_ENDPOINT,
+                            USB_ENDPOINT_HALT, data->bulk_in, buffer, 0,
+                            USBTMC_TIMEOUT);
+
+       if (rv < 0) {
+               dev_err(&data->usb_dev->dev, "usb_control_msg returned %d\n",
+                       rv);
+               goto exit;
+       }
+       rv = 0;
+
+exit:
+       kfree(buffer);
+       return rv;
+}
+
+static int get_capabilities(struct usbtmc_device_data *data)
+{
+       struct device *dev = &data->usb_dev->dev;
+       char *buffer;
+       int rv;
+
+       buffer = kmalloc(0x18, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       rv = usb_control_msg(data->usb_dev, usb_rcvctrlpipe(data->usb_dev, 0),
+                            USBTMC_REQUEST_GET_CAPABILITIES,
+                            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+                            0, 0, buffer, 0x18, USBTMC_TIMEOUT);
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               return rv;
+       }
+
+       dev_dbg(dev, "GET_CAPABILITIES returned %x\n", buffer[0]);
+       dev_dbg(dev, "Interface capabilities are %x\n", buffer[4]);
+       dev_dbg(dev, "Device capabilities are %x\n", buffer[5]);
+       dev_dbg(dev, "USB488 interface capabilities are %x\n", buffer[14]);
+       dev_dbg(dev, "USB488 device capabilities are %x\n", buffer[15]);
+       if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+               dev_err(dev, "GET_CAPABILITIES returned %x\n", buffer[0]);
+               return -EPERM;
+       }
+
+       data->capabilities.interface_capabilities = buffer[4];
+       data->capabilities.device_capabilities = buffer[5];
+       data->capabilities.usb488_interface_capabilities = buffer[14];
+       data->capabilities.usb488_device_capabilities = buffer[15];
+
+       kfree(buffer);
+       return 0;
+}
+
+#define capability_attribute(name)                                     \
+static ssize_t show_##name(struct device *dev,                         \
+                          struct device_attribute *attr, char *buf)    \
+{                                                                      \
+       struct usb_interface *intf = to_usb_interface(dev);             \
+       struct usbtmc_device_data *data = usb_get_intfdata(intf);       \
+                                                                       \
+       return sprintf(buf, "%d\n", data->capabilities.name);           \
+}                                                                      \
+static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
+
+capability_attribute(interface_capabilities);
+capability_attribute(device_capabilities);
+capability_attribute(usb488_interface_capabilities);
+capability_attribute(usb488_device_capabilities);
+
+static struct attribute *capability_attrs[] = {
+       &dev_attr_interface_capabilities.attr,
+       &dev_attr_device_capabilities.attr,
+       &dev_attr_usb488_interface_capabilities.attr,
+       &dev_attr_usb488_device_capabilities.attr,
+       NULL,
+};
+
+static struct attribute_group capability_attr_grp = {
+       .attrs = capability_attrs,
+};
+
+static ssize_t show_TermChar(struct device *dev,
+                            struct device_attribute *attr, char *buf)
+{
+       struct usb_interface *intf = to_usb_interface(dev);
+       struct usbtmc_device_data *data = usb_get_intfdata(intf);
+
+       return sprintf(buf, "%c\n", data->TermChar);
+}
+
+static ssize_t store_TermChar(struct device *dev,
+                             struct device_attribute *attr,
+                             const char *buf, size_t count)
+{
+       struct usb_interface *intf = to_usb_interface(dev);
+       struct usbtmc_device_data *data = usb_get_intfdata(intf);
+
+       if (count < 1)
+               return -EINVAL;
+       data->TermChar = buf[0];
+       return count;
+}
+static DEVICE_ATTR(TermChar, S_IRUGO, show_TermChar, store_TermChar);
+
+#define data_attribute(name)                                           \
+static ssize_t show_##name(struct device *dev,                         \
+                          struct device_attribute *attr, char *buf)    \
+{                                                                      \
+       struct usb_interface *intf = to_usb_interface(dev);             \
+       struct usbtmc_device_data *data = usb_get_intfdata(intf);       \
+                                                                       \
+       return sprintf(buf, "%d\n", data->name);                        \
+}                                                                      \
+static ssize_t store_##name(struct device *dev,                                \
+                           struct device_attribute *attr,              \
+                           const char *buf, size_t count)              \
+{                                                                      \
+       struct usb_interface *intf = to_usb_interface(dev);             \
+       struct usbtmc_device_data *data = usb_get_intfdata(intf);       \
+       ssize_t result;                                                 \
+       unsigned val;                                                   \
+                                                                       \
+       result = sscanf(buf, "%u\n", &val);                             \
+       if (result != 1)                                                \
+               result = -EINVAL;                                       \
+       data->name = val;                                               \
+       if (result < 0)                                                 \
+               return result;                                          \
+       else                                                            \
+               return count;                                           \
+}                                                                      \
+static DEVICE_ATTR(name, S_IRUGO, show_##name, store_##name)
+
+data_attribute(TermCharEnabled);
+data_attribute(auto_abort);
+
+static struct attribute *data_attrs[] = {
+       &dev_attr_TermChar.attr,
+       &dev_attr_TermCharEnabled.attr,
+       &dev_attr_auto_abort.attr,
+       NULL,
+};
+
+static struct attribute_group data_attr_grp = {
+       .attrs = data_attrs,
+};
+
+static int usbtmc_ioctl_indicator_pulse(struct usbtmc_device_data *data)
+{
+       struct device *dev;
+       u8 *buffer;
+       int rv;
+
+       dev = &data->intf->dev;
+
+       buffer = kmalloc(2, GFP_KERNEL);
+       if (!buffer)
+               return -ENOMEM;
+
+       rv = usb_control_msg(data->usb_dev,
+                            usb_rcvctrlpipe(data->usb_dev, 0),
+                            USBTMC_REQUEST_INDICATOR_PULSE,
+                            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+                            0, 0, buffer, 0x01, USBTMC_TIMEOUT);
+
+       if (rv < 0) {
+               dev_err(dev, "usb_control_msg returned %d\n", rv);
+               goto exit;
+       }
+
+       dev_dbg(dev, "INDICATOR_PULSE returned %x\n", buffer[0]);
+
+       if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+               dev_err(dev, "INDICATOR_PULSE returned %x\n", buffer[0]);
+               rv = -EPERM;
+               goto exit;
+       }
+       rv = 0;
+
+exit:
+       kfree(buffer);
+       return rv;
+}
+
+static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+       struct usbtmc_device_data *data;
+       int retval = -EBADRQC;
+
+       data = file->private_data;
+       mutex_lock(&data->io_mutex);
+
+       switch (cmd) {
+       case USBTMC_IOCTL_CLEAR_OUT_HALT:
+               retval = usbtmc_ioctl_clear_out_halt(data);
+
+       case USBTMC_IOCTL_CLEAR_IN_HALT:
+               retval = usbtmc_ioctl_clear_in_halt(data);
+
+       case USBTMC_IOCTL_INDICATOR_PULSE:
+               retval = usbtmc_ioctl_indicator_pulse(data);
+
+       case USBTMC_IOCTL_CLEAR:
+               retval = usbtmc_ioctl_clear(data);
+
+       case USBTMC_IOCTL_ABORT_BULK_OUT:
+               retval = usbtmc_ioctl_abort_bulk_out(data);
+
+       case USBTMC_IOCTL_ABORT_BULK_IN:
+               retval = usbtmc_ioctl_abort_bulk_in(data);
+       }
+
+       mutex_unlock(&data->io_mutex);
+       return retval;
+}
+
+static struct file_operations fops = {
+       .owner          = THIS_MODULE,
+       .read           = usbtmc_read,
+       .write          = usbtmc_write,
+       .open           = usbtmc_open,
+       .release        = usbtmc_release,
+       .unlocked_ioctl = usbtmc_ioctl,
+};
+
+static struct usb_class_driver usbtmc_class = {
+       .name =         "usbtmc%d",
+       .fops =         &fops,
+       .minor_base =   USBTMC_MINOR_BASE,
+};
+
+
+static int usbtmc_probe(struct usb_interface *intf,
+                       const struct usb_device_id *id)
+{
+       struct usbtmc_device_data *data;
+       struct usb_host_interface *iface_desc;
+       struct usb_endpoint_descriptor *endpoint;
+       int n;
+       int retcode;
+
+       dev_dbg(&intf->dev, "%s called\n", __func__);
+
+       data = kmalloc(sizeof(struct usbtmc_device_data), GFP_KERNEL);
+       if (!data) {
+               dev_err(&intf->dev, "Unable to allocate kernel memory\n");
+               return -ENOMEM;
+       }
+
+       data->intf = intf;
+       data->id = id;
+       data->usb_dev = usb_get_dev(interface_to_usbdev(intf));
+       usb_set_intfdata(intf, data);
+       kref_init(&data->kref);
+       mutex_init(&data->io_mutex);
+
+       /* Initialize USBTMC bTag and other fields */
+       data->bTag      = 1;
+       data->TermCharEnabled = 0;
+       data->TermChar = '\n';
+
+       /* USBTMC devices have only one setting, so use that */
+       iface_desc = data->intf->cur_altsetting;
+
+       /* Find bulk in endpoint */
+       for (n = 0; n < iface_desc->desc.bNumEndpoints; n++) {
+               endpoint = &iface_desc->endpoint[n].desc;
+
+               if (usb_endpoint_is_bulk_in(endpoint)) {
+                       data->bulk_in = endpoint->bEndpointAddress;
+                       dev_dbg(&intf->dev, "Found bulk in endpoint at %u\n",
+                               data->bulk_in);
+                       break;
+               }
+       }
+
+       /* Find bulk out endpoint */
+       for (n = 0; n < iface_desc->desc.bNumEndpoints; n++) {
+               endpoint = &iface_desc->endpoint[n].desc;
+
+               if (usb_endpoint_is_bulk_out(endpoint)) {
+                       data->bulk_out = endpoint->bEndpointAddress;
+                       dev_dbg(&intf->dev, "Found Bulk out endpoint at %u\n",
+                               data->bulk_out);
+                       break;
+               }
+       }
+
+       retcode = get_capabilities(data);
+       if (retcode)
+               dev_err(&intf->dev, "can't read capabilities\n");
+       else
+               retcode = sysfs_create_group(&intf->dev.kobj,
+                                            &capability_attr_grp);
+
+       retcode = sysfs_create_group(&intf->dev.kobj, &data_attr_grp);
+
+       retcode = usb_register_dev(intf, &usbtmc_class);
+       if (retcode) {
+               dev_err(&intf->dev, "Not able to get a minor"
+                       " (base %u, slice default): %d\n", USBTMC_MINOR_BASE,
+                       retcode);
+               goto error_register;
+       }
+       dev_dbg(&intf->dev, "Using minor number %d\n", intf->minor);
+
+       return 0;
+
+error_register:
+       sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
+       sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
+       kref_put(&data->kref, usbtmc_delete);
+       return retcode;
+}
+
+static void usbtmc_disconnect(struct usb_interface *intf)
+{
+       struct usbtmc_device_data *data;
+
+       dev_dbg(&intf->dev, "usbtmc_disconnect called\n");
+
+       data = usb_get_intfdata(intf);
+       usb_deregister_dev(intf, &usbtmc_class);
+       sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
+       sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
+       kref_put(&data->kref, usbtmc_delete);
+}
+
+static struct usb_driver usbtmc_driver = {
+       .name           = "usbtmc",
+       .id_table       = usbtmc_devices,
+       .probe          = usbtmc_probe,
+       .disconnect     = usbtmc_disconnect
+};
+
+static int __init usbtmc_init(void)
+{
+       int retcode;
+
+       retcode = usb_register(&usbtmc_driver);
+       if (retcode)
+               printk(KERN_ERR KBUILD_MODNAME": Unable to register driver\n");
+       return retcode;
+}
+module_init(usbtmc_init);
+
+static void __exit usbtmc_exit(void)
+{
+       usb_deregister(&usbtmc_driver);
+}
+module_exit(usbtmc_exit);
+
+MODULE_LICENSE("GPL");