USB: add USB test and measurement class driver

This driver was originaly written by Stefan Kopp, but massively
reworked by Greg for submission.

Thanks to Felipe Balbi <me@felipebalbi.com> for lots of work in cleaning
up this driver.

Thanks to Oliver Neukum <oliver@neukum.org> for reviewing previous
versions and pointing out problems.


Cc: Stefan Kopp <stefan_kopp@agilent.com>
Cc: Marcel Janssen <korgull@home.nl>
Cc: Felipe Balbi <me@felipebalbi.com>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 1098 insertions, 0 deletions

diff --git a/drivers/usb/class/Kconfig b/drivers/usb/class/Kconfig
index 66f17ed88cb..2519e320098 100644
--- a/drivers/usb/class/Kconfig
+++ b/drivers/usb/class/Kconfig
@@ -40,3 +40,13 @@ config USB_WDM
 	  To compile this driver as a module, choose M here: the
 	  module will be called cdc-wdm.
 
+config USB_TMC
+	tristate "USB Test and Measurement Class support"
+	depends on USB
+	help
+	  Say Y here if you want to connect a USB device that follows
+	  the USB.org specification for USB Test and Measurement devices
+	  to your computer's USB port.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called usbtmc.
diff --git a/drivers/usb/class/Makefile b/drivers/usb/class/Makefile
index 535d59a3060..32e85277b5c 100644
--- a/drivers/usb/class/Makefile
+++ b/drivers/usb/class/Makefile
@@ -6,3 +6,4 @@
 obj-$(CONFIG_USB_ACM)		+= cdc-acm.o
 obj-$(CONFIG_USB_PRINTER)	+= usblp.o
 obj-$(CONFIG_USB_WDM)		+= cdc-wdm.o
+obj-$(CONFIG_USB_TMC)		+= usbtmc.o
diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
new file mode 100644
index 00000000000..543811f6e6e
--- /dev/null
+++ b/drivers/usb/class/usbtmc.c
@@ -0,0 +1,1087 @@
+/**
+ * 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 = &current_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");