Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1723 insertions, 0 deletions

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
new file mode 100644
index 000000000..5c98f5612
--- /dev/null
+++ b/drivers/usb/class/usbtmc.c
@@ -0,0 +1,1723 @@
+// SPDX-License-Identifier: GPL-2.0+
+/**
+ * drivers/usb/class/usbtmc.c - USB Test & Measurement class driver
+ *
+ * Copyright (C) 2007 Stefan Kopp, Gechingen, Germany
+ * Copyright (C) 2008 Novell, Inc.
+ * Copyright (C) 2008 Greg Kroah-Hartman <gregkh@suse.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/kref.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/mutex.h>
+#include <linux/usb.h>
+#include <linux/compat.h>
+#include <linux/usb/tmc.h>
+
+
+#define USBTMC_HEADER_SIZE	12
+#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
+
+/* Minimum USB timeout (in milliseconds) */
+#define USBTMC_MIN_TIMEOUT	100
+/* Default USB timeout (in milliseconds) */
+#define USBTMC_TIMEOUT		5000
+
+/*
+ * 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 const struct usb_device_id usbtmc_devices[] = {
+	{ USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, 3, 0), },
+	{ USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, 3, 1), },
+	{ 0, } /* terminating entry */
+};
+MODULE_DEVICE_TABLE(usb, usbtmc_devices);
+
+/*
+ * This structure is the capabilities for the device
+ * See section 4.2.1.8 of the USBTMC specification,
+ * and section 4.2.2 of the USBTMC usb488 subclass
+ * 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;
+	struct list_head file_list;
+
+	unsigned int bulk_in;
+	unsigned int bulk_out;
+
+	u8 bTag;
+	u8 bTag_last_write;	/* needed for abort */
+	u8 bTag_last_read;	/* needed for abort */
+
+	/* data for interrupt in endpoint handling */
+	u8             bNotify1;
+	u8             bNotify2;
+	u16            ifnum;
+	u8             iin_bTag;
+	u8            *iin_buffer;
+	atomic_t       iin_data_valid;
+	unsigned int   iin_ep;
+	int            iin_ep_present;
+	int            iin_interval;
+	struct urb    *iin_urb;
+	u16            iin_wMaxPacketSize;
+
+	/* coalesced usb488_caps from usbtmc_dev_capabilities */
+	__u8 usb488_caps;
+
+	/* attributes from the USB TMC spec for this device */
+	u8 TermChar;
+	bool TermCharEnabled;
+	bool auto_abort;
+
+	bool zombie; /* fd of disconnected device */
+
+	struct usbtmc_dev_capabilities	capabilities;
+	struct kref kref;
+	struct mutex io_mutex;	/* only one i/o function running at a time */
+	wait_queue_head_t waitq;
+	struct fasync_struct *fasync;
+	spinlock_t dev_lock; /* lock for file_list */
+};
+#define to_usbtmc_data(d) container_of(d, struct usbtmc_device_data, kref)
+
+/*
+ * This structure holds private data for each USBTMC file handle.
+ */
+struct usbtmc_file_data {
+	struct usbtmc_device_data *data;
+	struct list_head file_elem;
+
+	u32            timeout;
+	u8             srq_byte;
+	atomic_t       srq_asserted;
+	u8             eom_val;
+	u8             term_char;
+	bool           term_char_enabled;
+};
+
+/* 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;
+	struct usbtmc_file_data *file_data;
+
+	intf = usb_find_interface(&usbtmc_driver, iminor(inode));
+	if (!intf) {
+		pr_err("can not find device for minor %d", iminor(inode));
+		return -ENODEV;
+	}
+
+	file_data = kzalloc(sizeof(*file_data), GFP_KERNEL);
+	if (!file_data)
+		return -ENOMEM;
+
+	data = usb_get_intfdata(intf);
+	/* Protect reference to data from file structure until release */
+	kref_get(&data->kref);
+
+	mutex_lock(&data->io_mutex);
+	file_data->data = data;
+
+	/* copy default values from device settings */
+	file_data->timeout = USBTMC_TIMEOUT;
+	file_data->term_char = data->TermChar;
+	file_data->term_char_enabled = data->TermCharEnabled;
+	file_data->eom_val = 1;
+
+	INIT_LIST_HEAD(&file_data->file_elem);
+	spin_lock_irq(&data->dev_lock);
+	list_add_tail(&file_data->file_elem, &data->file_list);
+	spin_unlock_irq(&data->dev_lock);
+	mutex_unlock(&data->io_mutex);
+
+	/* Store pointer in file structure's private data field */
+	filp->private_data = file_data;
+
+	return 0;
+}
+
+static int usbtmc_release(struct inode *inode, struct file *file)
+{
+	struct usbtmc_file_data *file_data = file->private_data;
+
+	/* prevent IO _AND_ usbtmc_interrupt */
+	mutex_lock(&file_data->data->io_mutex);
+	spin_lock_irq(&file_data->data->dev_lock);
+
+	list_del(&file_data->file_elem);
+
+	spin_unlock_irq(&file_data->data->dev_lock);
+	mutex_unlock(&file_data->data->io_mutex);
+
+	kref_put(&file_data->data->kref, usbtmc_delete);
+	file_data->data = NULL;
+	kfree(file_data);
+	return 0;
+}
+
+static int usbtmc_ioctl_abort_bulk_in(struct usbtmc_device_data *data)
+{
+	u8 *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 = usb_endpoint_maxp(&current_setting->endpoint[n].desc);
+
+	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_tag(struct usbtmc_device_data *data,
+					   u8 tag)
+{
+	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,
+			     tag, data->bulk_out,
+			     buffer, 2, USB_CTRL_GET_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:
+	/* do not stress device with subsequent requests */
+	msleep(50);
+	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,
+			     USB_CTRL_GET_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_clear_halt(data->usb_dev,
+			    usb_sndbulkpipe(data->usb_dev, data->bulk_out));
+
+	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_abort_bulk_out(struct usbtmc_device_data *data)
+{
+	return usbtmc_ioctl_abort_bulk_out_tag(data, data->bTag_last_write);
+}
+
+static int usbtmc488_ioctl_read_stb(struct usbtmc_file_data *file_data,
+				void __user *arg)
+{
+	struct usbtmc_device_data *data = file_data->data;
+	struct device *dev = &data->intf->dev;
+	int srq_asserted = 0;
+	u8 *buffer;
+	u8 tag;
+	__u8 stb;
+	int rv;
+
+	dev_dbg(dev, "Enter ioctl_read_stb iin_ep_present: %d\n",
+		data->iin_ep_present);
+
+	spin_lock_irq(&data->dev_lock);
+	srq_asserted = atomic_xchg(&file_data->srq_asserted, srq_asserted);
+	if (srq_asserted) {
+		/* a STB with SRQ is already received */
+		stb = file_data->srq_byte;
+		spin_unlock_irq(&data->dev_lock);
+		rv = put_user(stb, (__u8 __user *)arg);
+		dev_dbg(dev, "stb:0x%02x with srq received %d\n",
+			(unsigned int)stb, rv);
+		return rv;
+	}
+	spin_unlock_irq(&data->dev_lock);
+
+	buffer = kmalloc(8, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	atomic_set(&data->iin_data_valid, 0);
+
+	rv = usb_control_msg(data->usb_dev,
+			usb_rcvctrlpipe(data->usb_dev, 0),
+			USBTMC488_REQUEST_READ_STATUS_BYTE,
+			USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+			data->iin_bTag,
+			data->ifnum,
+			buffer, 0x03, USBTMC_TIMEOUT);
+	if (rv < 0) {
+		dev_err(dev, "stb usb_control_msg returned %d\n", rv);
+		goto exit;
+	}
+
+	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+		dev_err(dev, "control status returned %x\n", buffer[0]);
+		rv = -EIO;
+		goto exit;
+	}
+
+	if (data->iin_ep_present) {
+		rv = wait_event_interruptible_timeout(
+			data->waitq,
+			atomic_read(&data->iin_data_valid) != 0,
+			file_data->timeout);
+		if (rv < 0) {
+			dev_dbg(dev, "wait interrupted %d\n", rv);
+			goto exit;
+		}
+
+		if (rv == 0) {
+			dev_dbg(dev, "wait timed out\n");
+			rv = -ETIMEDOUT;
+			goto exit;
+		}
+
+		tag = data->bNotify1 & 0x7f;
+		if (tag != data->iin_bTag) {
+			dev_err(dev, "expected bTag %x got %x\n",
+				data->iin_bTag, tag);
+		}
+
+		stb = data->bNotify2;
+	} else {
+		stb = buffer[2];
+	}
+
+	rv = put_user(stb, (__u8 __user *)arg);
+	dev_dbg(dev, "stb:0x%02x received %d\n", (unsigned int)stb, rv);
+
+ exit:
+	/* bump interrupt bTag */
+	data->iin_bTag += 1;
+	if (data->iin_bTag > 127)
+		/* 1 is for SRQ see USBTMC-USB488 subclass spec section 4.3.1 */
+		data->iin_bTag = 2;
+
+	kfree(buffer);
+	return rv;
+}
+
+static int usbtmc488_ioctl_simple(struct usbtmc_device_data *data,
+				void __user *arg, unsigned int cmd)
+{
+	struct device *dev = &data->intf->dev;
+	__u8 val;
+	u8 *buffer;
+	u16 wValue;
+	int rv;
+
+	if (!(data->usb488_caps & USBTMC488_CAPABILITY_SIMPLE))
+		return -EINVAL;
+
+	buffer = kmalloc(8, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	if (cmd == USBTMC488_REQUEST_REN_CONTROL) {
+		rv = copy_from_user(&val, arg, sizeof(val));
+		if (rv) {
+			rv = -EFAULT;
+			goto exit;
+		}
+		wValue = val ? 1 : 0;
+	} else {
+		wValue = 0;
+	}
+
+	rv = usb_control_msg(data->usb_dev,
+			usb_rcvctrlpipe(data->usb_dev, 0),
+			cmd,
+			USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+			wValue,
+			data->ifnum,
+			buffer, 0x01, USBTMC_TIMEOUT);
+	if (rv < 0) {
+		dev_err(dev, "simple usb_control_msg failed %d\n", rv);
+		goto exit;
+	} else if (rv != 1) {
+		dev_warn(dev, "simple usb_control_msg returned %d\n", rv);
+		rv = -EIO;
+		goto exit;
+	}
+
+	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+		dev_err(dev, "simple control status returned %x\n", buffer[0]);
+		rv = -EIO;
+		goto exit;
+	}
+	rv = 0;
+
+ exit:
+	kfree(buffer);
+	return rv;
+}
+
+/*
+ * Sends a TRIGGER Bulk-OUT command message
+ * See the USBTMC-USB488 specification, Table 2.
+ *
+ * Also updates bTag_last_write.
+ */
+static int usbtmc488_ioctl_trigger(struct usbtmc_file_data *file_data)
+{
+	struct usbtmc_device_data *data = file_data->data;
+	int retval;
+	u8 *buffer;
+	int actual;
+
+	buffer = kzalloc(USBTMC_HEADER_SIZE, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	buffer[0] = 128;
+	buffer[1] = data->bTag;
+	buffer[2] = ~data->bTag;
+
+	retval = usb_bulk_msg(data->usb_dev,
+			      usb_sndbulkpipe(data->usb_dev,
+					      data->bulk_out),
+			      buffer, USBTMC_HEADER_SIZE,
+			      &actual, file_data->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++;
+
+	kfree(buffer);
+	if (retval < 0) {
+		dev_err(&data->intf->dev, "%s returned %d\n",
+			__func__, retval);
+		return retval;
+	}
+
+	return 0;
+}
+
+/*
+ * Sends a REQUEST_DEV_DEP_MSG_IN message on the Bulk-OUT endpoint.
+ * @transfer_size: number of bytes to request from the device.
+ *
+ * See the USBTMC specification, Table 4.
+ *
+ * Also updates bTag_last_write.
+ */
+static int send_request_dev_dep_msg_in(struct usbtmc_file_data *file_data,
+				       size_t transfer_size)
+{
+	struct usbtmc_device_data *data = file_data->data;
+	int retval;
+	u8 *buffer;
+	int actual;
+
+	buffer = kmalloc(USBTMC_HEADER_SIZE, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+	/* Setup IO buffer for REQUEST_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] = transfer_size >> 0;
+	buffer[5] = transfer_size >> 8;
+	buffer[6] = transfer_size >> 16;
+	buffer[7] = transfer_size >> 24;
+	buffer[8] = file_data->term_char_enabled * 2;
+	/* Use term character? */
+	buffer[9] = file_data->term_char;
+	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, USBTMC_HEADER_SIZE,
+			      &actual, file_data->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++;
+
+	kfree(buffer);
+	if (retval < 0) {
+		dev_err(&data->intf->dev, "usb_bulk_msg in send_request_dev_dep_msg_in() returned %d\n", retval);
+		return retval;
+	}
+
+	return 0;
+}
+
+static ssize_t usbtmc_read(struct file *filp, char __user *buf,
+			   size_t count, loff_t *f_pos)
+{
+	struct usbtmc_file_data *file_data;
+	struct usbtmc_device_data *data;
+	struct device *dev;
+	u32 n_characters;
+	u8 *buffer;
+	int actual;
+	size_t done;
+	size_t remaining;
+	int retval;
+	size_t this_part;
+
+	/* Get pointer to private data structure */
+	file_data = filp->private_data;
+	data = file_data->data;
+	dev = &data->intf->dev;
+
+	buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	mutex_lock(&data->io_mutex);
+	if (data->zombie) {
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	dev_dbg(dev, "usb_bulk_msg_in: count(%zu)\n", count);
+
+	retval = send_request_dev_dep_msg_in(file_data, count);
+
+	if (retval < 0) {
+		if (data->auto_abort)
+			usbtmc_ioctl_abort_bulk_out(data);
+		goto exit;
+	}
+
+	/* Loop until we have fetched everything we requested */
+	remaining = count;
+	this_part = remaining;
+	done = 0;
+
+	while (remaining > 0) {
+		/* Send bulk URB */
+		retval = usb_bulk_msg(data->usb_dev,
+				      usb_rcvbulkpipe(data->usb_dev,
+						      data->bulk_in),
+				      buffer, USBTMC_SIZE_IOBUFFER, &actual,
+				      file_data->timeout);
+
+		dev_dbg(dev, "usb_bulk_msg: retval(%u), done(%zu), remaining(%zu), actual(%d)\n", retval, done, remaining, actual);
+
+		/* Store bTag (in case we need to abort) */
+		data->bTag_last_read = data->bTag;
+
+		if (retval < 0) {
+			dev_dbg(dev, "Unable to read data, error %d\n", retval);
+			if (data->auto_abort)
+				usbtmc_ioctl_abort_bulk_in(data);
+			goto exit;
+		}
+
+		/* Parse header in first packet */
+		if (done == 0) {
+			/* Sanity checks for the header */
+			if (actual < USBTMC_HEADER_SIZE) {
+				dev_err(dev, "Device sent too small first packet: %u < %u\n", actual, USBTMC_HEADER_SIZE);
+				if (data->auto_abort)
+					usbtmc_ioctl_abort_bulk_in(data);
+				goto exit;
+			}
+
+			if (buffer[0] != 2) {
+				dev_err(dev, "Device sent reply with wrong MsgID: %u != 2\n", buffer[0]);
+				if (data->auto_abort)
+					usbtmc_ioctl_abort_bulk_in(data);
+				goto exit;
+			}
+
+			if (buffer[1] != data->bTag_last_write) {
+				dev_err(dev, "Device sent reply with wrong bTag: %u != %u\n", buffer[1], data->bTag_last_write);
+				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);
+
+			if (n_characters > this_part) {
+				dev_err(dev, "Device wants to return more data than requested: %u > %zu\n", n_characters, count);
+				if (data->auto_abort)
+					usbtmc_ioctl_abort_bulk_in(data);
+				goto exit;
+			}
+
+			/* Remove the USBTMC header */
+			actual -= USBTMC_HEADER_SIZE;
+
+			/* Check if the message is smaller than requested */
+			if (remaining > n_characters)
+				remaining = n_characters;
+			/* Remove padding if it exists */
+			if (actual > remaining)
+				actual = remaining;
+
+			dev_dbg(dev, "Bulk-IN header: N_characters(%u), bTransAttr(%u)\n", n_characters, buffer[8]);
+
+			remaining -= actual;
+
+			/* Terminate if end-of-message bit received from device */
+			if ((buffer[8] & 0x01) && (actual >= n_characters))
+				remaining = 0;
+
+			dev_dbg(dev, "Bulk-IN header: remaining(%zu), buf(%p), buffer(%p) done(%zu)\n", remaining,buf,buffer,done);
+
+
+			/* Copy buffer to user space */
+			if (copy_to_user(buf + done, &buffer[USBTMC_HEADER_SIZE], actual)) {
+				/* There must have been an addressing problem */
+				retval = -EFAULT;
+				goto exit;
+			}
+			done += actual;
+		}
+		else  {
+			if (actual > remaining)
+				actual = remaining;
+
+			remaining -= actual;
+
+			dev_dbg(dev, "Bulk-IN header cont: actual(%u), done(%zu), remaining(%zu), buf(%p), buffer(%p)\n", actual, done, remaining,buf,buffer);
+
+			/* Copy buffer to user space */
+			if (copy_to_user(buf + done, buffer, actual)) {
+				/* There must have been an addressing problem */
+				retval = -EFAULT;
+				goto exit;
+			}
+			done += actual;
+		}
+	}
+
+	/* 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_file_data *file_data;
+	struct usbtmc_device_data *data;
+	u8 *buffer;
+	int retval;
+	int actual;
+	unsigned long int n_bytes;
+	int remaining;
+	int done;
+	int this_part;
+
+	file_data = filp->private_data;
+	data = file_data->data;
+
+	buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	mutex_lock(&data->io_mutex);
+	if (data->zombie) {
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	remaining = count;
+	done = 0;
+
+	while (remaining > 0) {
+		if (remaining > USBTMC_SIZE_IOBUFFER - USBTMC_HEADER_SIZE) {
+			this_part = USBTMC_SIZE_IOBUFFER - USBTMC_HEADER_SIZE;
+			buffer[8] = 0;
+		} else {
+			this_part = remaining;
+			buffer[8] = file_data->eom_val;
+		}
+
+		/* 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 >> 0;
+		buffer[5] = this_part >> 8;
+		buffer[6] = this_part >> 16;
+		buffer[7] = this_part >> 24;
+		/* buffer[8] is set above... */
+		buffer[9] = 0; /* Reserved */
+		buffer[10] = 0; /* Reserved */
+		buffer[11] = 0; /* Reserved */
+
+		if (copy_from_user(&buffer[USBTMC_HEADER_SIZE], buf + done, this_part)) {
+			retval = -EFAULT;
+			goto exit;
+		}
+
+		n_bytes = roundup(USBTMC_HEADER_SIZE + this_part, 4);
+		memset(buffer + USBTMC_HEADER_SIZE + this_part, 0, n_bytes - (USBTMC_HEADER_SIZE + this_part));
+
+		do {
+			retval = usb_bulk_msg(data->usb_dev,
+					      usb_sndbulkpipe(data->usb_dev,
+							      data->bulk_out),
+					      buffer, n_bytes,
+					      &actual, file_data->timeout);
+			if (retval != 0)
+				break;
+			n_bytes -= actual;
+		} while (n_bytes);
+
+		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 = 0;
+	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 = usb_endpoint_maxp(desc);
+	}
+
+	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");
+
+			actual = 0;
+			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_clear_halt(data->usb_dev,
+			    usb_sndbulkpipe(data->usb_dev, data->bulk_out));
+	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)
+{
+	int rv;
+
+	rv = usb_clear_halt(data->usb_dev,
+			    usb_sndbulkpipe(data->usb_dev, data->bulk_out));
+
+	if (rv < 0) {
+		dev_err(&data->usb_dev->dev, "usb_control_msg returned %d\n",
+			rv);
+		return rv;
+	}
+	return 0;
+}
+
+static int usbtmc_ioctl_clear_in_halt(struct usbtmc_device_data *data)
+{
+	int rv;
+
+	rv = usb_clear_halt(data->usb_dev,
+			    usb_rcvbulkpipe(data->usb_dev, data->bulk_in));
+
+	if (rv < 0) {
+		dev_err(&data->usb_dev->dev, "usb_control_msg returned %d\n",
+			rv);
+		return rv;
+	}
+	return 0;
+}
+
+static int get_capabilities(struct usbtmc_device_data *data)
+{
+	struct device *dev = &data->usb_dev->dev;
+	char *buffer;
+	int rv = 0;
+
+	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);
+		goto err_out;
+	}
+
+	dev_dbg(dev, "GET_CAPABILITIES returned %x\n", buffer[0]);
+	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+		dev_err(dev, "GET_CAPABILITIES returned %x\n", buffer[0]);
+		rv = -EPERM;
+		goto err_out;
+	}
+	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]);
+
+	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];
+	data->usb488_caps = (buffer[14] & 0x07) | ((buffer[15] & 0x0f) << 4);
+	rv = 0;
+
+err_out:
+	kfree(buffer);
+	return rv;
+}
+
+#define capability_attribute(name)					\
+static ssize_t name##_show(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_RO(name)
+
+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 const struct attribute_group capability_attr_grp = {
+	.attrs = capability_attrs,
+};
+
+static ssize_t TermChar_show(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 TermChar_store(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_RW(TermChar);
+
+#define data_attribute(name)						\
+static ssize_t name##_show(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 name##_store(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_RW(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 const 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;
+}
+
+/*
+ * Get the usb timeout value
+ */
+static int usbtmc_ioctl_get_timeout(struct usbtmc_file_data *file_data,
+				void __user *arg)
+{
+	u32 timeout;
+
+	timeout = file_data->timeout;
+
+	return put_user(timeout, (__u32 __user *)arg);
+}
+
+/*
+ * Set the usb timeout value
+ */
+static int usbtmc_ioctl_set_timeout(struct usbtmc_file_data *file_data,
+				void __user *arg)
+{
+	u32 timeout;
+
+	if (get_user(timeout, (__u32 __user *)arg))
+		return -EFAULT;
+
+	/* Note that timeout = 0 means
+	 * MAX_SCHEDULE_TIMEOUT in usb_control_msg
+	 */
+	if (timeout < USBTMC_MIN_TIMEOUT)
+		return -EINVAL;
+
+	file_data->timeout = timeout;
+
+	return 0;
+}
+
+/*
+ * enables/disables sending EOM on write
+ */
+static int usbtmc_ioctl_eom_enable(struct usbtmc_file_data *file_data,
+				void __user *arg)
+{
+	u8 eom_enable;
+
+	if (copy_from_user(&eom_enable, arg, sizeof(eom_enable)))
+		return -EFAULT;
+
+	if (eom_enable > 1)
+		return -EINVAL;
+
+	file_data->eom_val = eom_enable;
+
+	return 0;
+}
+
+/*
+ * Configure termination character for read()
+ */
+static int usbtmc_ioctl_config_termc(struct usbtmc_file_data *file_data,
+				void __user *arg)
+{
+	struct usbtmc_termchar termc;
+
+	if (copy_from_user(&termc, arg, sizeof(termc)))
+		return -EFAULT;
+
+	if ((termc.term_char_enabled > 1) ||
+		(termc.term_char_enabled &&
+		!(file_data->data->capabilities.device_capabilities & 1)))
+		return -EINVAL;
+
+	file_data->term_char = termc.term_char;
+	file_data->term_char_enabled = termc.term_char_enabled;
+
+	return 0;
+}
+
+static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct usbtmc_file_data *file_data;
+	struct usbtmc_device_data *data;
+	int retval = -EBADRQC;
+
+	file_data = file->private_data;
+	data = file_data->data;
+
+	mutex_lock(&data->io_mutex);
+	if (data->zombie) {
+		retval = -ENODEV;
+		goto skip_io_on_zombie;
+	}
+
+	switch (cmd) {
+	case USBTMC_IOCTL_CLEAR_OUT_HALT:
+		retval = usbtmc_ioctl_clear_out_halt(data);
+		break;
+
+	case USBTMC_IOCTL_CLEAR_IN_HALT:
+		retval = usbtmc_ioctl_clear_in_halt(data);
+		break;
+
+	case USBTMC_IOCTL_INDICATOR_PULSE:
+		retval = usbtmc_ioctl_indicator_pulse(data);
+		break;
+
+	case USBTMC_IOCTL_CLEAR:
+		retval = usbtmc_ioctl_clear(data);
+		break;
+
+	case USBTMC_IOCTL_ABORT_BULK_OUT:
+		retval = usbtmc_ioctl_abort_bulk_out(data);
+		break;
+
+	case USBTMC_IOCTL_ABORT_BULK_IN:
+		retval = usbtmc_ioctl_abort_bulk_in(data);
+		break;
+
+	case USBTMC_IOCTL_GET_TIMEOUT:
+		retval = usbtmc_ioctl_get_timeout(file_data,
+						  (void __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_SET_TIMEOUT:
+		retval = usbtmc_ioctl_set_timeout(file_data,
+						  (void __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_EOM_ENABLE:
+		retval = usbtmc_ioctl_eom_enable(file_data,
+						 (void __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_CONFIG_TERMCHAR:
+		retval = usbtmc_ioctl_config_termc(file_data,
+						   (void __user *)arg);
+		break;
+
+	case USBTMC488_IOCTL_GET_CAPS:
+		retval = copy_to_user((void __user *)arg,
+				&data->usb488_caps,
+				sizeof(data->usb488_caps));
+		if (retval)
+			retval = -EFAULT;
+		break;
+
+	case USBTMC488_IOCTL_READ_STB:
+		retval = usbtmc488_ioctl_read_stb(file_data,
+						  (void __user *)arg);
+		break;
+
+	case USBTMC488_IOCTL_REN_CONTROL:
+		retval = usbtmc488_ioctl_simple(data, (void __user *)arg,
+						USBTMC488_REQUEST_REN_CONTROL);
+		break;
+
+	case USBTMC488_IOCTL_GOTO_LOCAL:
+		retval = usbtmc488_ioctl_simple(data, (void __user *)arg,
+						USBTMC488_REQUEST_GOTO_LOCAL);
+		break;
+
+	case USBTMC488_IOCTL_LOCAL_LOCKOUT:
+		retval = usbtmc488_ioctl_simple(data, (void __user *)arg,
+						USBTMC488_REQUEST_LOCAL_LOCKOUT);
+		break;
+
+	case USBTMC488_IOCTL_TRIGGER:
+		retval = usbtmc488_ioctl_trigger(file_data);
+		break;
+	}
+
+skip_io_on_zombie:
+	mutex_unlock(&data->io_mutex);
+	return retval;
+}
+
+static int usbtmc_fasync(int fd, struct file *file, int on)
+{
+	struct usbtmc_file_data *file_data = file->private_data;
+
+	return fasync_helper(fd, file, on, &file_data->data->fasync);
+}
+
+static __poll_t usbtmc_poll(struct file *file, poll_table *wait)
+{
+	struct usbtmc_file_data *file_data = file->private_data;
+	struct usbtmc_device_data *data = file_data->data;
+	__poll_t mask;
+
+	mutex_lock(&data->io_mutex);
+
+	if (data->zombie) {
+		mask = EPOLLHUP | EPOLLERR;
+		goto no_poll;
+	}
+
+	poll_wait(file, &data->waitq, wait);
+
+	mask = (atomic_read(&file_data->srq_asserted)) ? EPOLLPRI : 0;
+
+no_poll:
+	mutex_unlock(&data->io_mutex);
+	return mask;
+}
+
+static const struct file_operations fops = {
+	.owner		= THIS_MODULE,
+	.read		= usbtmc_read,
+	.write		= usbtmc_write,
+	.open		= usbtmc_open,
+	.release	= usbtmc_release,
+	.unlocked_ioctl	= usbtmc_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= usbtmc_ioctl,
+#endif
+	.fasync         = usbtmc_fasync,
+	.poll           = usbtmc_poll,
+	.llseek		= default_llseek,
+};
+
+static struct usb_class_driver usbtmc_class = {
+	.name =		"usbtmc%d",
+	.fops =		&fops,
+	.minor_base =	USBTMC_MINOR_BASE,
+};
+
+static void usbtmc_interrupt(struct urb *urb)
+{
+	struct usbtmc_device_data *data = urb->context;
+	struct device *dev = &data->intf->dev;
+	int status = urb->status;
+	int rv;
+
+	dev_dbg(&data->intf->dev, "int status: %d len %d\n",
+		status, urb->actual_length);
+
+	switch (status) {
+	case 0: /* SUCCESS */
+		/* check for valid STB notification */
+		if (data->iin_buffer[0] > 0x81) {
+			data->bNotify1 = data->iin_buffer[0];
+			data->bNotify2 = data->iin_buffer[1];
+			atomic_set(&data->iin_data_valid, 1);
+			wake_up_interruptible(&data->waitq);
+			goto exit;
+		}
+		/* check for SRQ notification */
+		if (data->iin_buffer[0] == 0x81) {
+			unsigned long flags;
+			struct list_head *elem;
+
+			if (data->fasync)
+				kill_fasync(&data->fasync,
+					SIGIO, POLL_PRI);
+
+			spin_lock_irqsave(&data->dev_lock, flags);
+			list_for_each(elem, &data->file_list) {
+				struct usbtmc_file_data *file_data;
+
+				file_data = list_entry(elem,
+						       struct usbtmc_file_data,
+						       file_elem);
+				file_data->srq_byte = data->iin_buffer[1];
+				atomic_set(&file_data->srq_asserted, 1);
+			}
+			spin_unlock_irqrestore(&data->dev_lock, flags);
+
+			dev_dbg(dev, "srq received bTag %x stb %x\n",
+				(unsigned int)data->iin_buffer[0],
+				(unsigned int)data->iin_buffer[1]);
+			wake_up_interruptible_all(&data->waitq);
+			goto exit;
+		}
+		dev_warn(dev, "invalid notification: %x\n",
+			 data->iin_buffer[0]);
+		break;
+	case -EOVERFLOW:
+		dev_err(dev, "overflow with length %d, actual length is %d\n",
+			data->iin_wMaxPacketSize, urb->actual_length);
+		/* fall through */
+	default:
+		/* urb terminated, clean up */
+		dev_dbg(dev, "urb terminated, status: %d\n", status);
+		return;
+	}
+exit:
+	rv = usb_submit_urb(urb, GFP_ATOMIC);
+	if (rv)
+		dev_err(dev, "usb_submit_urb failed: %d\n", rv);
+}
+
+static void usbtmc_free_int(struct usbtmc_device_data *data)
+{
+	if (!data->iin_ep_present || !data->iin_urb)
+		return;
+	usb_kill_urb(data->iin_urb);
+	kfree(data->iin_buffer);
+	usb_free_urb(data->iin_urb);
+	kref_put(&data->kref, usbtmc_delete);
+}
+
+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 *bulk_in, *bulk_out, *int_in;
+	int retcode;
+
+	dev_dbg(&intf->dev, "%s called\n", __func__);
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		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);
+	init_waitqueue_head(&data->waitq);
+	atomic_set(&data->iin_data_valid, 0);
+	INIT_LIST_HEAD(&data->file_list);
+	spin_lock_init(&data->dev_lock);
+
+	data->zombie = 0;
+
+	/* Initialize USBTMC bTag and other fields */
+	data->bTag	= 1;
+	data->TermCharEnabled = 0;
+	data->TermChar = '\n';
+	/*  2 <= bTag <= 127   USBTMC-USB488 subclass specification 4.3.1 */
+	data->iin_bTag = 2;
+
+	/* USBTMC devices have only one setting, so use that */
+	iface_desc = data->intf->cur_altsetting;
+	data->ifnum = iface_desc->desc.bInterfaceNumber;
+
+	/* Find bulk endpoints */
+	retcode = usb_find_common_endpoints(iface_desc,
+			&bulk_in, &bulk_out, NULL, NULL);
+	if (retcode) {
+		dev_err(&intf->dev, "bulk endpoints not found\n");
+		goto err_put;
+	}
+
+	data->bulk_in = bulk_in->bEndpointAddress;
+	dev_dbg(&intf->dev, "Found bulk in endpoint at %u\n", data->bulk_in);
+
+	data->bulk_out = bulk_out->bEndpointAddress;
+	dev_dbg(&intf->dev, "Found Bulk out endpoint at %u\n", data->bulk_out);
+
+	/* Find int endpoint */
+	retcode = usb_find_int_in_endpoint(iface_desc, &int_in);
+	if (!retcode) {
+		data->iin_ep_present = 1;
+		data->iin_ep = int_in->bEndpointAddress;
+		data->iin_wMaxPacketSize = usb_endpoint_maxp(int_in);
+		data->iin_interval = int_in->bInterval;
+		dev_dbg(&intf->dev, "Found Int in endpoint at %u\n",
+				data->iin_ep);
+	}
+
+	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);
+
+	if (data->iin_ep_present) {
+		/* allocate int urb */
+		data->iin_urb = usb_alloc_urb(0, GFP_KERNEL);
+		if (!data->iin_urb) {
+			retcode = -ENOMEM;
+			goto error_register;
+		}
+
+		/* Protect interrupt in endpoint data until iin_urb is freed */
+		kref_get(&data->kref);
+
+		/* allocate buffer for interrupt in */
+		data->iin_buffer = kmalloc(data->iin_wMaxPacketSize,
+					GFP_KERNEL);
+		if (!data->iin_buffer) {
+			retcode = -ENOMEM;
+			goto error_register;
+		}
+
+		/* fill interrupt urb */
+		usb_fill_int_urb(data->iin_urb, data->usb_dev,
+				usb_rcvintpipe(data->usb_dev, data->iin_ep),
+				data->iin_buffer, data->iin_wMaxPacketSize,
+				usbtmc_interrupt,
+				data, data->iin_interval);
+
+		retcode = usb_submit_urb(data->iin_urb, GFP_KERNEL);
+		if (retcode) {
+			dev_err(&intf->dev, "Failed to submit iin_urb\n");
+			goto error_register;
+		}
+	}
+
+	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);
+	usbtmc_free_int(data);
+err_put:
+	kref_put(&data->kref, usbtmc_delete);
+	return retcode;
+}
+
+static void usbtmc_disconnect(struct usb_interface *intf)
+{
+	struct usbtmc_device_data *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);
+	mutex_lock(&data->io_mutex);
+	data->zombie = 1;
+	wake_up_interruptible_all(&data->waitq);
+	mutex_unlock(&data->io_mutex);
+	usbtmc_free_int(data);
+	kref_put(&data->kref, usbtmc_delete);
+}
+
+static int usbtmc_suspend(struct usb_interface *intf, pm_message_t message)
+{
+	/* this driver does not have pending URBs */
+	return 0;
+}
+
+static int usbtmc_resume(struct usb_interface *intf)
+{
+	return 0;
+}
+
+static struct usb_driver usbtmc_driver = {
+	.name		= "usbtmc",
+	.id_table	= usbtmc_devices,
+	.probe		= usbtmc_probe,
+	.disconnect	= usbtmc_disconnect,
+	.suspend	= usbtmc_suspend,
+	.resume		= usbtmc_resume,
+};
+
+module_usb_driver(usbtmc_driver);
+
+MODULE_LICENSE("GPL");