Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 2595 insertions, 0 deletions

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
new file mode 100644
index 000000000..311007b1d
--- /dev/null
+++ b/drivers/usb/class/usbtmc.c
@@ -0,0 +1,2595 @@
+// 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>
+ * Copyright (C) 2018 IVI Foundation, Inc.
+ */
+
+#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>
+
+/* Increment API VERSION when changing tmc.h with new flags or ioctls
+ * or when changing a significant behavior of the driver.
+ */
+#define USBTMC_API_VERSION (3)
+
+#define USBTMC_HEADER_SIZE	12
+#define USBTMC_MINOR_BASE	176
+
+/* Minimum USB timeout (in milliseconds) */
+#define USBTMC_MIN_TIMEOUT	100
+/* Default USB timeout (in milliseconds) */
+#define USBTMC_TIMEOUT		5000
+
+/* Max number of urbs used in write transfers */
+#define MAX_URBS_IN_FLIGHT	16
+/* I/O buffer size used in generic read/write functions */
+#define USBTMC_BUFSIZE		(4096)
+
+/*
+ * 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 */
+
+	/* packet size of IN bulk */
+	u16            wMaxPacketSize;
+
+	/* 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;
+
+	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;
+	atomic_t       closing;
+	u8             bmTransferAttributes; /* member of DEV_DEP_MSG_IN */
+
+	u8             eom_val;
+	u8             term_char;
+	bool           term_char_enabled;
+	bool           auto_abort;
+
+	spinlock_t     err_lock; /* lock for errors */
+
+	struct usb_anchor submitted;
+
+	/* data for generic_write */
+	struct semaphore limit_write_sem;
+	u32 out_transfer_size;
+	int out_status;
+
+	/* data for generic_read */
+	u32 in_transfer_size;
+	int in_status;
+	int in_urbs_used;
+	struct usb_anchor in_anchor;
+	wait_queue_head_t wait_bulk_in;
+};
+
+/* Forward declarations */
+static struct usb_driver usbtmc_driver;
+static void usbtmc_draw_down(struct usbtmc_file_data *file_data);
+
+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;
+
+	spin_lock_init(&file_data->err_lock);
+	sema_init(&file_data->limit_write_sem, MAX_URBS_IN_FLIGHT);
+	init_usb_anchor(&file_data->submitted);
+	init_usb_anchor(&file_data->in_anchor);
+	init_waitqueue_head(&file_data->wait_bulk_in);
+
+	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;
+
+	atomic_set(&file_data->closing, 0);
+
+	file_data->timeout = USBTMC_TIMEOUT;
+	file_data->term_char = '\n';
+	file_data->term_char_enabled = 0;
+	file_data->auto_abort = 0;
+	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;
+}
+
+/*
+ * usbtmc_flush - called before file handle is closed
+ */
+static int usbtmc_flush(struct file *file, fl_owner_t id)
+{
+	struct usbtmc_file_data *file_data;
+	struct usbtmc_device_data *data;
+
+	file_data = file->private_data;
+	if (file_data == NULL)
+		return -ENODEV;
+
+	atomic_set(&file_data->closing, 1);
+	data = file_data->data;
+
+	/* wait for io to stop */
+	mutex_lock(&data->io_mutex);
+
+	usbtmc_draw_down(file_data);
+
+	spin_lock_irq(&file_data->err_lock);
+	file_data->in_status = 0;
+	file_data->in_transfer_size = 0;
+	file_data->in_urbs_used = 0;
+	file_data->out_status = 0;
+	file_data->out_transfer_size = 0;
+	spin_unlock_irq(&file_data->err_lock);
+
+	wake_up_interruptible_all(&data->waitq);
+	mutex_unlock(&data->io_mutex);
+
+	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_tag(struct usbtmc_device_data *data,
+					  u8 tag)
+{
+	u8 *buffer;
+	struct device *dev;
+	int rv;
+	int n;
+	int actual;
+
+	dev = &data->intf->dev;
+	buffer = kmalloc(USBTMC_BUFSIZE, 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,
+			     tag, data->bulk_in,
+			     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_IN returned %x with tag %02x\n",
+		buffer[0], buffer[1]);
+
+	if (buffer[0] == USBTMC_STATUS_FAILED) {
+		/* No transfer in progress and the Bulk-OUT FIFO is empty. */
+		rv = 0;
+		goto exit;
+	}
+
+	if (buffer[0] == USBTMC_STATUS_TRANSFER_NOT_IN_PROGRESS) {
+		/* The device returns this status if either:
+		 * - There is a transfer in progress, but the specified bTag
+		 *   does not match.
+		 * - There is no transfer in progress, but the Bulk-OUT FIFO
+		 *   is not empty.
+		 */
+		rv = -ENOMSG;
+		goto exit;
+	}
+
+	if (buffer[0] != USBTMC_STATUS_SUCCESS) {
+		dev_err(dev, "INITIATE_ABORT_BULK_IN returned %x\n",
+			buffer[0]);
+		rv = -EPERM;
+		goto exit;
+	}
+
+	n = 0;
+
+usbtmc_abort_bulk_in_status:
+	dev_dbg(dev, "Reading from bulk in EP\n");
+
+	/* Data must be present. So use low timeout 300 ms */
+	actual = 0;
+	rv = usb_bulk_msg(data->usb_dev,
+			  usb_rcvbulkpipe(data->usb_dev,
+					  data->bulk_in),
+			  buffer, USBTMC_BUFSIZE,
+			  &actual, 300);
+
+	print_hex_dump_debug("usbtmc ", DUMP_PREFIX_NONE, 16, 1,
+			     buffer, actual, true);
+
+	n++;
+
+	if (rv < 0) {
+		dev_err(dev, "usb_bulk_msg returned %d\n", rv);
+		if (rv != -ETIMEDOUT)
+			goto exit;
+	}
+
+	if (actual == USBTMC_BUFSIZE)
+		goto usbtmc_abort_bulk_in_status;
+
+	if (n >= USBTMC_MAX_READS_TO_CLEAR_BULK_IN) {
+		dev_err(dev, "Couldn't clear device buffer within %d cycles\n",
+			USBTMC_MAX_READS_TO_CLEAR_BULK_IN);
+		rv = -EPERM;
+		goto exit;
+	}
+
+	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,
+			     USB_CTRL_GET_TIMEOUT);
+
+	if (rv < 0) {
+		dev_err(dev, "usb_control_msg returned %d\n", rv);
+		goto exit;
+	}
+
+	dev_dbg(dev, "CHECK_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, "CHECK_ABORT_BULK_IN returned %x\n", buffer[0]);
+		rv = -EPERM;
+		goto exit;
+	}
+
+	if ((buffer[1] & 1) > 0) {
+		/* The device has 1 or more queued packets the Host can read */
+		goto usbtmc_abort_bulk_in_status;
+	}
+
+	/* The Host must send CHECK_ABORT_BULK_IN_STATUS at a later time. */
+	rv = -EAGAIN;
+exit:
+	kfree(buffer);
+	return rv;
+}
+
+static int usbtmc_ioctl_abort_bulk_in(struct usbtmc_device_data *data)
+{
+	return usbtmc_ioctl_abort_bulk_in_tag(data, data->bTag_last_read);
+}
+
+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 usbtmc_get_stb(struct usbtmc_file_data *file_data, __u8 *stb)
+{
+	struct usbtmc_device_data *data = file_data->data;
+	struct device *dev = &data->intf->dev;
+	u8 *buffer;
+	u8 tag;
+	int rv;
+
+	dev_dbg(dev, "Enter ioctl_read_stb iin_ep_present: %d\n",
+		data->iin_ep_present);
+
+	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, USB_CTRL_GET_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];
+	}
+
+	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_read_stb(struct usbtmc_file_data *file_data,
+				void __user *arg)
+{
+	int srq_asserted = 0;
+	__u8 stb;
+	int rv;
+
+	rv = usbtmc_get_stb(file_data, &stb);
+
+	if (rv > 0) {
+		srq_asserted = atomic_xchg(&file_data->srq_asserted,
+					srq_asserted);
+		if (srq_asserted)
+			stb |= 0x40; /* Set RQS bit */
+
+		rv = put_user(stb, (__u8 __user *)arg);
+	}
+	return rv;
+
+}
+
+static int usbtmc_ioctl_get_srq_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 stb = 0;
+	int rv;
+
+	spin_lock_irq(&data->dev_lock);
+	srq_asserted  = atomic_xchg(&file_data->srq_asserted, srq_asserted);
+
+	if (srq_asserted) {
+		stb = file_data->srq_byte;
+		spin_unlock_irq(&data->dev_lock);
+		rv = put_user(stb, (__u8 __user *)arg);
+	} else {
+		spin_unlock_irq(&data->dev_lock);
+		rv = -ENOMSG;
+	}
+
+	dev_dbg(dev, "stb:0x%02x with srq received %d\n", (unsigned int)stb, rv);
+
+	return rv;
+}
+
+static int usbtmc488_ioctl_wait_srq(struct usbtmc_file_data *file_data,
+				    __u32 __user *arg)
+{
+	struct usbtmc_device_data *data = file_data->data;
+	struct device *dev = &data->intf->dev;
+	int rv;
+	u32 timeout;
+	unsigned long expire;
+
+	if (!data->iin_ep_present) {
+		dev_dbg(dev, "no interrupt endpoint present\n");
+		return -EFAULT;
+	}
+
+	if (get_user(timeout, arg))
+		return -EFAULT;
+
+	expire = msecs_to_jiffies(timeout);
+
+	mutex_unlock(&data->io_mutex);
+
+	rv = wait_event_interruptible_timeout(
+			data->waitq,
+			atomic_read(&file_data->srq_asserted) != 0 ||
+			atomic_read(&file_data->closing),
+			expire);
+
+	mutex_lock(&data->io_mutex);
+
+	/* Note! disconnect or close could be called in the meantime */
+	if (atomic_read(&file_data->closing) || data->zombie)
+		rv = -ENODEV;
+
+	if (rv < 0) {
+		/* dev can be invalid now! */
+		pr_debug("%s - wait interrupted %d\n", __func__, rv);
+		return rv;
+	}
+
+	if (rv == 0) {
+		dev_dbg(dev, "%s - wait timed out\n", __func__);
+		return -ETIMEDOUT;
+	}
+
+	dev_dbg(dev, "%s - srq asserted\n", __func__);
+	return 0;
+}
+
+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, USB_CTRL_GET_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;
+}
+
+static struct urb *usbtmc_create_urb(void)
+{
+	const size_t bufsize = USBTMC_BUFSIZE;
+	u8 *dmabuf = NULL;
+	struct urb *urb = usb_alloc_urb(0, GFP_KERNEL);
+
+	if (!urb)
+		return NULL;
+
+	dmabuf = kmalloc(bufsize, GFP_KERNEL);
+	if (!dmabuf) {
+		usb_free_urb(urb);
+		return NULL;
+	}
+
+	urb->transfer_buffer = dmabuf;
+	urb->transfer_buffer_length = bufsize;
+	urb->transfer_flags |= URB_FREE_BUFFER;
+	return urb;
+}
+
+static void usbtmc_read_bulk_cb(struct urb *urb)
+{
+	struct usbtmc_file_data *file_data = urb->context;
+	int status = urb->status;
+	unsigned long flags;
+
+	/* sync/async unlink faults aren't errors */
+	if (status) {
+		if (!(/* status == -ENOENT || */
+			status == -ECONNRESET ||
+			status == -EREMOTEIO || /* Short packet */
+			status == -ESHUTDOWN))
+			dev_err(&file_data->data->intf->dev,
+			"%s - nonzero read bulk status received: %d\n",
+			__func__, status);
+
+		spin_lock_irqsave(&file_data->err_lock, flags);
+		if (!file_data->in_status)
+			file_data->in_status = status;
+		spin_unlock_irqrestore(&file_data->err_lock, flags);
+	}
+
+	spin_lock_irqsave(&file_data->err_lock, flags);
+	file_data->in_transfer_size += urb->actual_length;
+	dev_dbg(&file_data->data->intf->dev,
+		"%s - total size: %u current: %d status: %d\n",
+		__func__, file_data->in_transfer_size,
+		urb->actual_length, status);
+	spin_unlock_irqrestore(&file_data->err_lock, flags);
+	usb_anchor_urb(urb, &file_data->in_anchor);
+
+	wake_up_interruptible(&file_data->wait_bulk_in);
+	wake_up_interruptible(&file_data->data->waitq);
+}
+
+static inline bool usbtmc_do_transfer(struct usbtmc_file_data *file_data)
+{
+	bool data_or_error;
+
+	spin_lock_irq(&file_data->err_lock);
+	data_or_error = !usb_anchor_empty(&file_data->in_anchor)
+			|| file_data->in_status;
+	spin_unlock_irq(&file_data->err_lock);
+	dev_dbg(&file_data->data->intf->dev, "%s: returns %d\n", __func__,
+		data_or_error);
+	return data_or_error;
+}
+
+static ssize_t usbtmc_generic_read(struct usbtmc_file_data *file_data,
+				   void __user *user_buffer,
+				   u32 transfer_size,
+				   u32 *transferred,
+				   u32 flags)
+{
+	struct usbtmc_device_data *data = file_data->data;
+	struct device *dev = &data->intf->dev;
+	u32 done = 0;
+	u32 remaining;
+	const u32 bufsize = USBTMC_BUFSIZE;
+	int retval = 0;
+	u32 max_transfer_size;
+	unsigned long expire;
+	int bufcount = 1;
+	int again = 0;
+
+	/* mutex already locked */
+
+	*transferred = done;
+
+	max_transfer_size = transfer_size;
+
+	if (flags & USBTMC_FLAG_IGNORE_TRAILER) {
+		/* The device may send extra alignment bytes (up to
+		 * wMaxPacketSize – 1) to avoid sending a zero-length
+		 * packet
+		 */
+		remaining = transfer_size;
+		if ((max_transfer_size % data->wMaxPacketSize) == 0)
+			max_transfer_size += (data->wMaxPacketSize - 1);
+	} else {
+		/* round down to bufsize to avoid truncated data left */
+		if (max_transfer_size > bufsize) {
+			max_transfer_size =
+				roundup(max_transfer_size + 1 - bufsize,
+					bufsize);
+		}
+		remaining = max_transfer_size;
+	}
+
+	spin_lock_irq(&file_data->err_lock);
+
+	if (file_data->in_status) {
+		/* return the very first error */
+		retval = file_data->in_status;
+		spin_unlock_irq(&file_data->err_lock);
+		goto error;
+	}
+
+	if (flags & USBTMC_FLAG_ASYNC) {
+		if (usb_anchor_empty(&file_data->in_anchor))
+			again = 1;
+
+		if (file_data->in_urbs_used == 0) {
+			file_data->in_transfer_size = 0;
+			file_data->in_status = 0;
+		}
+	} else {
+		file_data->in_transfer_size = 0;
+		file_data->in_status = 0;
+	}
+
+	if (max_transfer_size == 0) {
+		bufcount = 0;
+	} else {
+		bufcount = roundup(max_transfer_size, bufsize) / bufsize;
+		if (bufcount > file_data->in_urbs_used)
+			bufcount -= file_data->in_urbs_used;
+		else
+			bufcount = 0;
+
+		if (bufcount + file_data->in_urbs_used > MAX_URBS_IN_FLIGHT) {
+			bufcount = MAX_URBS_IN_FLIGHT -
+					file_data->in_urbs_used;
+		}
+	}
+	spin_unlock_irq(&file_data->err_lock);
+
+	dev_dbg(dev, "%s: requested=%u flags=0x%X size=%u bufs=%d used=%d\n",
+		__func__, transfer_size, flags,
+		max_transfer_size, bufcount, file_data->in_urbs_used);
+
+	while (bufcount > 0) {
+		u8 *dmabuf = NULL;
+		struct urb *urb = usbtmc_create_urb();
+
+		if (!urb) {
+			retval = -ENOMEM;
+			goto error;
+		}
+
+		dmabuf = urb->transfer_buffer;
+
+		usb_fill_bulk_urb(urb, data->usb_dev,
+			usb_rcvbulkpipe(data->usb_dev, data->bulk_in),
+			dmabuf, bufsize,
+			usbtmc_read_bulk_cb, file_data);
+
+		usb_anchor_urb(urb, &file_data->submitted);
+		retval = usb_submit_urb(urb, GFP_KERNEL);
+		/* urb is anchored. We can release our reference. */
+		usb_free_urb(urb);
+		if (unlikely(retval)) {
+			usb_unanchor_urb(urb);
+			goto error;
+		}
+		file_data->in_urbs_used++;
+		bufcount--;
+	}
+
+	if (again) {
+		dev_dbg(dev, "%s: ret=again\n", __func__);
+		return -EAGAIN;
+	}
+
+	if (user_buffer == NULL)
+		return -EINVAL;
+
+	expire = msecs_to_jiffies(file_data->timeout);
+
+	while (max_transfer_size > 0) {
+		u32 this_part;
+		struct urb *urb = NULL;
+
+		if (!(flags & USBTMC_FLAG_ASYNC)) {
+			dev_dbg(dev, "%s: before wait time %lu\n",
+				__func__, expire);
+			retval = wait_event_interruptible_timeout(
+				file_data->wait_bulk_in,
+				usbtmc_do_transfer(file_data),
+				expire);
+
+			dev_dbg(dev, "%s: wait returned %d\n",
+				__func__, retval);
+
+			if (retval <= 0) {
+				if (retval == 0)
+					retval = -ETIMEDOUT;
+				goto error;
+			}
+		}
+
+		urb = usb_get_from_anchor(&file_data->in_anchor);
+		if (!urb) {
+			if (!(flags & USBTMC_FLAG_ASYNC)) {
+				/* synchronous case: must not happen */
+				retval = -EFAULT;
+				goto error;
+			}
+
+			/* asynchronous case: ready, do not block or wait */
+			*transferred = done;
+			dev_dbg(dev, "%s: (async) done=%u ret=0\n",
+				__func__, done);
+			return 0;
+		}
+
+		file_data->in_urbs_used--;
+
+		if (max_transfer_size > urb->actual_length)
+			max_transfer_size -= urb->actual_length;
+		else
+			max_transfer_size = 0;
+
+		if (remaining > urb->actual_length)
+			this_part = urb->actual_length;
+		else
+			this_part = remaining;
+
+		print_hex_dump_debug("usbtmc ", DUMP_PREFIX_NONE, 16, 1,
+			urb->transfer_buffer, urb->actual_length, true);
+
+		if (copy_to_user(user_buffer + done,
+				 urb->transfer_buffer, this_part)) {
+			usb_free_urb(urb);
+			retval = -EFAULT;
+			goto error;
+		}
+
+		remaining -= this_part;
+		done += this_part;
+
+		spin_lock_irq(&file_data->err_lock);
+		if (urb->status) {
+			/* return the very first error */
+			retval = file_data->in_status;
+			spin_unlock_irq(&file_data->err_lock);
+			usb_free_urb(urb);
+			goto error;
+		}
+		spin_unlock_irq(&file_data->err_lock);
+
+		if (urb->actual_length < bufsize) {
+			/* short packet or ZLP received => ready */
+			usb_free_urb(urb);
+			retval = 1;
+			break;
+		}
+
+		if (!(flags & USBTMC_FLAG_ASYNC) &&
+		    max_transfer_size > (bufsize * file_data->in_urbs_used)) {
+			/* resubmit, since other buffers still not enough */
+			usb_anchor_urb(urb, &file_data->submitted);
+			retval = usb_submit_urb(urb, GFP_KERNEL);
+			if (unlikely(retval)) {
+				usb_unanchor_urb(urb);
+				usb_free_urb(urb);
+				goto error;
+			}
+			file_data->in_urbs_used++;
+		}
+		usb_free_urb(urb);
+		retval = 0;
+	}
+
+error:
+	*transferred = done;
+
+	dev_dbg(dev, "%s: before kill\n", __func__);
+	/* Attention: killing urbs can take long time (2 ms) */
+	usb_kill_anchored_urbs(&file_data->submitted);
+	dev_dbg(dev, "%s: after kill\n", __func__);
+	usb_scuttle_anchored_urbs(&file_data->in_anchor);
+	file_data->in_urbs_used = 0;
+	file_data->in_status = 0; /* no spinlock needed here */
+	dev_dbg(dev, "%s: done=%u ret=%d\n", __func__, done, retval);
+
+	return retval;
+}
+
+static ssize_t usbtmc_ioctl_generic_read(struct usbtmc_file_data *file_data,
+					 void __user *arg)
+{
+	struct usbtmc_message msg;
+	ssize_t retval = 0;
+
+	/* mutex already locked */
+
+	if (copy_from_user(&msg, arg, sizeof(struct usbtmc_message)))
+		return -EFAULT;
+
+	retval = usbtmc_generic_read(file_data, msg.message,
+				     msg.transfer_size, &msg.transferred,
+				     msg.flags);
+
+	if (put_user(msg.transferred,
+		     &((struct usbtmc_message __user *)arg)->transferred))
+		return -EFAULT;
+
+	return retval;
+}
+
+static void usbtmc_write_bulk_cb(struct urb *urb)
+{
+	struct usbtmc_file_data *file_data = urb->context;
+	int wakeup = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&file_data->err_lock, flags);
+	file_data->out_transfer_size += urb->actual_length;
+
+	/* sync/async unlink faults aren't errors */
+	if (urb->status) {
+		if (!(urb->status == -ENOENT ||
+			urb->status == -ECONNRESET ||
+			urb->status == -ESHUTDOWN))
+			dev_err(&file_data->data->intf->dev,
+				"%s - nonzero write bulk status received: %d\n",
+				__func__, urb->status);
+
+		if (!file_data->out_status) {
+			file_data->out_status = urb->status;
+			wakeup = 1;
+		}
+	}
+	spin_unlock_irqrestore(&file_data->err_lock, flags);
+
+	dev_dbg(&file_data->data->intf->dev,
+		"%s - write bulk total size: %u\n",
+		__func__, file_data->out_transfer_size);
+
+	up(&file_data->limit_write_sem);
+	if (usb_anchor_empty(&file_data->submitted) || wakeup)
+		wake_up_interruptible(&file_data->data->waitq);
+}
+
+static ssize_t usbtmc_generic_write(struct usbtmc_file_data *file_data,
+				    const void __user *user_buffer,
+				    u32 transfer_size,
+				    u32 *transferred,
+				    u32 flags)
+{
+	struct usbtmc_device_data *data = file_data->data;
+	struct device *dev;
+	u32 done = 0;
+	u32 remaining;
+	unsigned long expire;
+	const u32 bufsize = USBTMC_BUFSIZE;
+	struct urb *urb = NULL;
+	int retval = 0;
+	u32 timeout;
+
+	*transferred = 0;
+
+	/* Get pointer to private data structure */
+	dev = &data->intf->dev;
+
+	dev_dbg(dev, "%s: size=%u flags=0x%X sema=%u\n",
+		__func__, transfer_size, flags,
+		file_data->limit_write_sem.count);
+
+	if (flags & USBTMC_FLAG_APPEND) {
+		spin_lock_irq(&file_data->err_lock);
+		retval = file_data->out_status;
+		spin_unlock_irq(&file_data->err_lock);
+		if (retval < 0)
+			return retval;
+	} else {
+		spin_lock_irq(&file_data->err_lock);
+		file_data->out_transfer_size = 0;
+		file_data->out_status = 0;
+		spin_unlock_irq(&file_data->err_lock);
+	}
+
+	remaining = transfer_size;
+	if (remaining > INT_MAX)
+		remaining = INT_MAX;
+
+	timeout = file_data->timeout;
+	expire = msecs_to_jiffies(timeout);
+
+	while (remaining > 0) {
+		u32 this_part, aligned;
+		u8 *buffer = NULL;
+
+		if (flags & USBTMC_FLAG_ASYNC) {
+			if (down_trylock(&file_data->limit_write_sem)) {
+				retval = (done)?(0):(-EAGAIN);
+				goto exit;
+			}
+		} else {
+			retval = down_timeout(&file_data->limit_write_sem,
+					      expire);
+			if (retval < 0) {
+				retval = -ETIMEDOUT;
+				goto error;
+			}
+		}
+
+		spin_lock_irq(&file_data->err_lock);
+		retval = file_data->out_status;
+		spin_unlock_irq(&file_data->err_lock);
+		if (retval < 0) {
+			up(&file_data->limit_write_sem);
+			goto error;
+		}
+
+		/* prepare next urb to send */
+		urb = usbtmc_create_urb();
+		if (!urb) {
+			retval = -ENOMEM;
+			up(&file_data->limit_write_sem);
+			goto error;
+		}
+		buffer = urb->transfer_buffer;
+
+		if (remaining > bufsize)
+			this_part = bufsize;
+		else
+			this_part = remaining;
+
+		if (copy_from_user(buffer, user_buffer + done, this_part)) {
+			retval = -EFAULT;
+			up(&file_data->limit_write_sem);
+			goto error;
+		}
+
+		print_hex_dump_debug("usbtmc ", DUMP_PREFIX_NONE,
+			16, 1, buffer, this_part, true);
+
+		/* fill bulk with 32 bit alignment to meet USBTMC specification
+		 * (size + 3 & ~3) rounds up and simplifies user code
+		 */
+		aligned = (this_part + 3) & ~3;
+		dev_dbg(dev, "write(size:%u align:%u done:%u)\n",
+			(unsigned int)this_part,
+			(unsigned int)aligned,
+			(unsigned int)done);
+
+		usb_fill_bulk_urb(urb, data->usb_dev,
+			usb_sndbulkpipe(data->usb_dev, data->bulk_out),
+			urb->transfer_buffer, aligned,
+			usbtmc_write_bulk_cb, file_data);
+
+		usb_anchor_urb(urb, &file_data->submitted);
+		retval = usb_submit_urb(urb, GFP_KERNEL);
+		if (unlikely(retval)) {
+			usb_unanchor_urb(urb);
+			up(&file_data->limit_write_sem);
+			goto error;
+		}
+
+		usb_free_urb(urb);
+		urb = NULL; /* urb will be finally released by usb driver */
+
+		remaining -= this_part;
+		done += this_part;
+	}
+
+	/* All urbs are on the fly */
+	if (!(flags & USBTMC_FLAG_ASYNC)) {
+		if (!usb_wait_anchor_empty_timeout(&file_data->submitted,
+						   timeout)) {
+			retval = -ETIMEDOUT;
+			goto error;
+		}
+	}
+
+	retval = 0;
+	goto exit;
+
+error:
+	usb_kill_anchored_urbs(&file_data->submitted);
+exit:
+	usb_free_urb(urb);
+
+	spin_lock_irq(&file_data->err_lock);
+	if (!(flags & USBTMC_FLAG_ASYNC))
+		done = file_data->out_transfer_size;
+	if (!retval && file_data->out_status)
+		retval = file_data->out_status;
+	spin_unlock_irq(&file_data->err_lock);
+
+	*transferred = done;
+
+	dev_dbg(dev, "%s: done=%u, retval=%d, urbstat=%d\n",
+		__func__, done, retval, file_data->out_status);
+
+	return retval;
+}
+
+static ssize_t usbtmc_ioctl_generic_write(struct usbtmc_file_data *file_data,
+					  void __user *arg)
+{
+	struct usbtmc_message msg;
+	ssize_t retval = 0;
+
+	/* mutex already locked */
+
+	if (copy_from_user(&msg, arg, sizeof(struct usbtmc_message)))
+		return -EFAULT;
+
+	retval = usbtmc_generic_write(file_data, msg.message,
+				      msg.transfer_size, &msg.transferred,
+				      msg.flags);
+
+	if (put_user(msg.transferred,
+		     &((struct usbtmc_message __user *)arg)->transferred))
+		return -EFAULT;
+
+	return retval;
+}
+
+/*
+ * Get the generic write result
+ */
+static ssize_t usbtmc_ioctl_write_result(struct usbtmc_file_data *file_data,
+				void __user *arg)
+{
+	u32 transferred;
+	int retval;
+
+	spin_lock_irq(&file_data->err_lock);
+	transferred = file_data->out_transfer_size;
+	retval = file_data->out_status;
+	spin_unlock_irq(&file_data->err_lock);
+
+	if (put_user(transferred, (__u32 __user *)arg))
+		return -EFAULT;
+
+	return retval;
+}
+
+/*
+ * 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,
+				       u32 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, "%s returned %d\n",
+			__func__, retval);
+
+	return retval;
+}
+
+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;
+	const u32 bufsize = USBTMC_BUFSIZE;
+	u32 n_characters;
+	u8 *buffer;
+	int actual;
+	u32 done = 0;
+	u32 remaining;
+	int retval;
+
+	/* Get pointer to private data structure */
+	file_data = filp->private_data;
+	data = file_data->data;
+	dev = &data->intf->dev;
+
+	buffer = kmalloc(bufsize, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	mutex_lock(&data->io_mutex);
+	if (data->zombie) {
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	if (count > INT_MAX)
+		count = INT_MAX;
+
+	dev_dbg(dev, "%s(count:%zu)\n", __func__, count);
+
+	retval = send_request_dev_dep_msg_in(file_data, count);
+
+	if (retval < 0) {
+		if (file_data->auto_abort)
+			usbtmc_ioctl_abort_bulk_out(data);
+		goto exit;
+	}
+
+	/* Loop until we have fetched everything we requested */
+	remaining = count;
+	actual = 0;
+
+	/* Send bulk URB */
+	retval = usb_bulk_msg(data->usb_dev,
+			      usb_rcvbulkpipe(data->usb_dev,
+					      data->bulk_in),
+			      buffer, bufsize, &actual,
+			      file_data->timeout);
+
+	dev_dbg(dev, "%s: bulk_msg retval(%u), actual(%d)\n",
+		__func__, retval, actual);
+
+	/* Store bTag (in case we need to abort) */
+	data->bTag_last_read = data->bTag;
+
+	if (retval < 0) {
+		if (file_data->auto_abort)
+			usbtmc_ioctl_abort_bulk_in(data);
+		goto exit;
+	}
+
+	/* 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 (file_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 (file_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 (file_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);
+
+	file_data->bmTransferAttributes = buffer[8];
+
+	dev_dbg(dev, "Bulk-IN header: N_characters(%u), bTransAttr(%u)\n",
+		n_characters, buffer[8]);
+
+	if (n_characters > remaining) {
+		dev_err(dev, "Device wants to return more data than requested: %u > %zu\n",
+			n_characters, count);
+		if (file_data->auto_abort)
+			usbtmc_ioctl_abort_bulk_in(data);
+		goto exit;
+	}
+
+	print_hex_dump_debug("usbtmc ", DUMP_PREFIX_NONE,
+			     16, 1, buffer, actual, true);
+
+	remaining = n_characters;
+
+	/* Remove the USBTMC header */
+	actual -= USBTMC_HEADER_SIZE;
+
+	/* Remove padding if it exists */
+	if (actual > remaining)
+		actual = remaining;
+
+	remaining -= actual;
+
+	/* Copy buffer to user space */
+	if (copy_to_user(buf, &buffer[USBTMC_HEADER_SIZE], actual)) {
+		/* There must have been an addressing problem */
+		retval = -EFAULT;
+		goto exit;
+	}
+
+	if ((actual + USBTMC_HEADER_SIZE) == bufsize) {
+		retval = usbtmc_generic_read(file_data, buf + actual,
+					     remaining,
+					     &done,
+					     USBTMC_FLAG_IGNORE_TRAILER);
+		if (retval < 0)
+			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;
+	struct urb *urb = NULL;
+	ssize_t retval = 0;
+	u8 *buffer;
+	u32 remaining, done;
+	u32 transfersize, aligned, buflen;
+
+	file_data = filp->private_data;
+	data = file_data->data;
+
+	mutex_lock(&data->io_mutex);
+
+	if (data->zombie) {
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	done = 0;
+
+	spin_lock_irq(&file_data->err_lock);
+	file_data->out_transfer_size = 0;
+	file_data->out_status = 0;
+	spin_unlock_irq(&file_data->err_lock);
+
+	if (!count)
+		goto exit;
+
+	if (down_trylock(&file_data->limit_write_sem)) {
+		/* previous calls were async */
+		retval = -EBUSY;
+		goto exit;
+	}
+
+	urb = usbtmc_create_urb();
+	if (!urb) {
+		retval = -ENOMEM;
+		up(&file_data->limit_write_sem);
+		goto exit;
+	}
+
+	buffer = urb->transfer_buffer;
+	buflen = urb->transfer_buffer_length;
+
+	if (count > INT_MAX) {
+		transfersize = INT_MAX;
+		buffer[8] = 0;
+	} else {
+		transfersize = count;
+		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] = transfersize >> 0;
+	buffer[5] = transfersize >> 8;
+	buffer[6] = transfersize >> 16;
+	buffer[7] = transfersize >> 24;
+	/* buffer[8] is set above... */
+	buffer[9] = 0; /* Reserved */
+	buffer[10] = 0; /* Reserved */
+	buffer[11] = 0; /* Reserved */
+
+	remaining = transfersize;
+
+	if (transfersize + USBTMC_HEADER_SIZE > buflen) {
+		transfersize = buflen - USBTMC_HEADER_SIZE;
+		aligned = buflen;
+	} else {
+		aligned = (transfersize + (USBTMC_HEADER_SIZE + 3)) & ~3;
+	}
+
+	if (copy_from_user(&buffer[USBTMC_HEADER_SIZE], buf, transfersize)) {
+		retval = -EFAULT;
+		up(&file_data->limit_write_sem);
+		goto exit;
+	}
+
+	dev_dbg(&data->intf->dev, "%s(size:%u align:%u)\n", __func__,
+		(unsigned int)transfersize, (unsigned int)aligned);
+
+	print_hex_dump_debug("usbtmc ", DUMP_PREFIX_NONE,
+			     16, 1, buffer, aligned, true);
+
+	usb_fill_bulk_urb(urb, data->usb_dev,
+		usb_sndbulkpipe(data->usb_dev, data->bulk_out),
+		urb->transfer_buffer, aligned,
+		usbtmc_write_bulk_cb, file_data);
+
+	usb_anchor_urb(urb, &file_data->submitted);
+	retval = usb_submit_urb(urb, GFP_KERNEL);
+	if (unlikely(retval)) {
+		usb_unanchor_urb(urb);
+		up(&file_data->limit_write_sem);
+		goto exit;
+	}
+
+	remaining -= transfersize;
+
+	data->bTag_last_write = data->bTag;
+	data->bTag++;
+
+	if (!data->bTag)
+		data->bTag++;
+
+	/* call generic_write even when remaining = 0 */
+	retval = usbtmc_generic_write(file_data, buf + transfersize, remaining,
+				      &done, USBTMC_FLAG_APPEND);
+	/* truncate alignment bytes */
+	if (done > remaining)
+		done = remaining;
+
+	/*add size of first urb*/
+	done += transfersize;
+
+	if (retval < 0) {
+		usb_kill_anchored_urbs(&file_data->submitted);
+
+		dev_err(&data->intf->dev,
+			"Unable to send data, error %d\n", (int)retval);
+		if (file_data->auto_abort)
+			usbtmc_ioctl_abort_bulk_out(data);
+		goto exit;
+	}
+
+	retval = done;
+exit:
+	usb_free_urb(urb);
+	mutex_unlock(&data->io_mutex);
+	return retval;
+}
+
+static int usbtmc_ioctl_clear(struct usbtmc_device_data *data)
+{
+	struct device *dev;
+	u8 *buffer;
+	int rv;
+	int n;
+	int actual = 0;
+
+	dev = &data->intf->dev;
+
+	dev_dbg(dev, "Sending INITIATE_CLEAR request\n");
+
+	buffer = kmalloc(USBTMC_BUFSIZE, 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, USB_CTRL_GET_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;
+	}
+
+	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, USB_CTRL_GET_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) != 0) {
+		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_BUFSIZE,
+					  &actual, USB_CTRL_GET_TIMEOUT);
+
+			print_hex_dump_debug("usbtmc ", DUMP_PREFIX_NONE,
+					     16, 1, buffer, actual, true);
+
+			n++;
+
+			if (rv < 0) {
+				dev_err(dev, "usb_control_msg returned %d\n",
+					rv);
+				goto exit;
+			}
+		} while ((actual == USBTMC_BUFSIZE) &&
+			  (n < USBTMC_MAX_READS_TO_CLEAR_BULK_IN));
+	} else {
+		/* do not stress device with subsequent requests */
+		msleep(50);
+		n++;
+	}
+
+	if (n >= USBTMC_MAX_READS_TO_CLEAR_BULK_IN) {
+		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_clear_halt 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, "%s returned %d\n", __func__, rv);
+	return rv;
+}
+
+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, "%s returned %d\n", __func__, rv);
+	return rv;
+}
+
+static int usbtmc_ioctl_cancel_io(struct usbtmc_file_data *file_data)
+{
+	spin_lock_irq(&file_data->err_lock);
+	file_data->in_status = -ECANCELED;
+	file_data->out_status = -ECANCELED;
+	spin_unlock_irq(&file_data->err_lock);
+	usb_kill_anchored_urbs(&file_data->submitted);
+	return 0;
+}
+
+static int usbtmc_ioctl_cleanup_io(struct usbtmc_file_data *file_data)
+{
+	usb_kill_anchored_urbs(&file_data->submitted);
+	usb_scuttle_anchored_urbs(&file_data->in_anchor);
+	spin_lock_irq(&file_data->err_lock);
+	file_data->in_status = 0;
+	file_data->in_transfer_size = 0;
+	file_data->out_status = 0;
+	file_data->out_transfer_size = 0;
+	spin_unlock_irq(&file_data->err_lock);
+
+	file_data->in_urbs_used = 0;
+	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, USB_CTRL_GET_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 *usbtmc_attrs[] = {
+	&dev_attr_interface_capabilities.attr,
+	&dev_attr_device_capabilities.attr,
+	&dev_attr_usb488_interface_capabilities.attr,
+	&dev_attr_usb488_device_capabilities.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(usbtmc);
+
+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, USB_CTRL_GET_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 int usbtmc_ioctl_request(struct usbtmc_device_data *data,
+				void __user *arg)
+{
+	struct device *dev = &data->intf->dev;
+	struct usbtmc_ctrlrequest request;
+	u8 *buffer = NULL;
+	int rv;
+	unsigned int is_in, pipe;
+	unsigned long res;
+
+	res = copy_from_user(&request, arg, sizeof(struct usbtmc_ctrlrequest));
+	if (res)
+		return -EFAULT;
+
+	if (request.req.wLength > USBTMC_BUFSIZE)
+		return -EMSGSIZE;
+	if (request.req.wLength == 0)	/* Length-0 requests are never IN */
+		request.req.bRequestType &= ~USB_DIR_IN;
+
+	is_in = request.req.bRequestType & USB_DIR_IN;
+
+	if (request.req.wLength) {
+		buffer = kmalloc(request.req.wLength, GFP_KERNEL);
+		if (!buffer)
+			return -ENOMEM;
+
+		if (!is_in) {
+			/* Send control data to device */
+			res = copy_from_user(buffer, request.data,
+					     request.req.wLength);
+			if (res) {
+				rv = -EFAULT;
+				goto exit;
+			}
+		}
+	}
+
+	if (is_in)
+		pipe = usb_rcvctrlpipe(data->usb_dev, 0);
+	else
+		pipe = usb_sndctrlpipe(data->usb_dev, 0);
+	rv = usb_control_msg(data->usb_dev,
+			pipe,
+			request.req.bRequest,
+			request.req.bRequestType,
+			request.req.wValue,
+			request.req.wIndex,
+			buffer, request.req.wLength, USB_CTRL_GET_TIMEOUT);
+
+	if (rv < 0) {
+		dev_err(dev, "%s failed %d\n", __func__, rv);
+		goto exit;
+	}
+
+	if (rv && is_in) {
+		/* Read control data from device */
+		res = copy_to_user(request.data, buffer, rv);
+		if (res)
+			rv = -EFAULT;
+	}
+
+ 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;
+	__u8 tmp_byte;
+
+	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_CTRL_REQUEST:
+		retval = usbtmc_ioctl_request(data, (void __user *)arg);
+		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 USBTMC_IOCTL_WRITE:
+		retval = usbtmc_ioctl_generic_write(file_data,
+						    (void __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_READ:
+		retval = usbtmc_ioctl_generic_read(file_data,
+						   (void __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_WRITE_RESULT:
+		retval = usbtmc_ioctl_write_result(file_data,
+						   (void __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_API_VERSION:
+		retval = put_user(USBTMC_API_VERSION,
+				  (__u32 __user *)arg);
+		break;
+
+	case USBTMC488_IOCTL_GET_CAPS:
+		retval = put_user(data->usb488_caps,
+				  (unsigned char __user *)arg);
+		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;
+
+	case USBTMC488_IOCTL_WAIT_SRQ:
+		retval = usbtmc488_ioctl_wait_srq(file_data,
+						  (__u32 __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_MSG_IN_ATTR:
+		retval = put_user(file_data->bmTransferAttributes,
+				  (__u8 __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_AUTO_ABORT:
+		retval = get_user(tmp_byte, (unsigned char __user *)arg);
+		if (retval == 0)
+			file_data->auto_abort = !!tmp_byte;
+		break;
+
+	case USBTMC_IOCTL_GET_STB:
+		retval = usbtmc_get_stb(file_data, &tmp_byte);
+		if (retval > 0)
+			retval = put_user(tmp_byte, (__u8 __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_GET_SRQ_STB:
+		retval = usbtmc_ioctl_get_srq_stb(file_data,
+						  (void __user *)arg);
+		break;
+
+	case USBTMC_IOCTL_CANCEL_IO:
+		retval = usbtmc_ioctl_cancel_io(file_data);
+		break;
+
+	case USBTMC_IOCTL_CLEANUP_IO:
+		retval = usbtmc_ioctl_cleanup_io(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);
+
+	/* Note that EPOLLPRI is now assigned to SRQ, and
+	 * EPOLLIN|EPOLLRDNORM to normal read data.
+	 */
+	mask = 0;
+	if (atomic_read(&file_data->srq_asserted))
+		mask |= EPOLLPRI;
+
+	/* Note that the anchor submitted includes all urbs for BULK IN
+	 * and OUT. So EPOLLOUT is signaled when BULK OUT is empty and
+	 * all BULK IN urbs are completed and moved to in_anchor.
+	 */
+	if (usb_anchor_empty(&file_data->submitted))
+		mask |= (EPOLLOUT | EPOLLWRNORM);
+	if (!usb_anchor_empty(&file_data->in_anchor))
+		mask |= (EPOLLIN | EPOLLRDNORM);
+
+	spin_lock_irq(&file_data->err_lock);
+	if (file_data->in_status || file_data->out_status)
+		mask |= EPOLLERR;
+	spin_unlock_irq(&file_data->err_lock);
+
+	dev_dbg(&data->intf->dev, "poll mask = %x\n", mask);
+
+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,
+	.flush		= usbtmc_flush,
+	.unlocked_ioctl	= usbtmc_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+	.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);
+		fallthrough;
+	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);
+	data->iin_buffer = NULL;
+	usb_free_urb(data->iin_urb);
+	data->iin_urb = NULL;
+	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;
+	/*  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;
+	}
+
+	retcode = -EINVAL;
+	data->bulk_in = bulk_in->bEndpointAddress;
+	data->wMaxPacketSize = usb_endpoint_maxp(bulk_in);
+	if (!data->wMaxPacketSize)
+		goto err_put;
+	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");
+
+	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 = 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:
+	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);
+	struct list_head *elem;
+
+	usb_deregister_dev(intf, &usbtmc_class);
+	mutex_lock(&data->io_mutex);
+	data->zombie = 1;
+	wake_up_interruptible_all(&data->waitq);
+	list_for_each(elem, &data->file_list) {
+		struct usbtmc_file_data *file_data;
+
+		file_data = list_entry(elem,
+				       struct usbtmc_file_data,
+				       file_elem);
+		usb_kill_anchored_urbs(&file_data->submitted);
+		usb_scuttle_anchored_urbs(&file_data->in_anchor);
+	}
+	mutex_unlock(&data->io_mutex);
+	usbtmc_free_int(data);
+	kref_put(&data->kref, usbtmc_delete);
+}
+
+static void usbtmc_draw_down(struct usbtmc_file_data *file_data)
+{
+	int time;
+
+	time = usb_wait_anchor_empty_timeout(&file_data->submitted, 1000);
+	if (!time)
+		usb_kill_anchored_urbs(&file_data->submitted);
+	usb_scuttle_anchored_urbs(&file_data->in_anchor);
+}
+
+static int usbtmc_suspend(struct usb_interface *intf, pm_message_t message)
+{
+	struct usbtmc_device_data *data = usb_get_intfdata(intf);
+	struct list_head *elem;
+
+	if (!data)
+		return 0;
+
+	mutex_lock(&data->io_mutex);
+	list_for_each(elem, &data->file_list) {
+		struct usbtmc_file_data *file_data;
+
+		file_data = list_entry(elem,
+				       struct usbtmc_file_data,
+				       file_elem);
+		usbtmc_draw_down(file_data);
+	}
+
+	if (data->iin_ep_present && data->iin_urb)
+		usb_kill_urb(data->iin_urb);
+
+	mutex_unlock(&data->io_mutex);
+	return 0;
+}
+
+static int usbtmc_resume(struct usb_interface *intf)
+{
+	struct usbtmc_device_data *data = usb_get_intfdata(intf);
+	int retcode = 0;
+
+	if (data->iin_ep_present && data->iin_urb)
+		retcode = usb_submit_urb(data->iin_urb, GFP_KERNEL);
+	if (retcode)
+		dev_err(&intf->dev, "Failed to submit iin_urb\n");
+
+	return retcode;
+}
+
+static int usbtmc_pre_reset(struct usb_interface *intf)
+{
+	struct usbtmc_device_data *data  = usb_get_intfdata(intf);
+	struct list_head *elem;
+
+	if (!data)
+		return 0;
+
+	mutex_lock(&data->io_mutex);
+
+	list_for_each(elem, &data->file_list) {
+		struct usbtmc_file_data *file_data;
+
+		file_data = list_entry(elem,
+				       struct usbtmc_file_data,
+				       file_elem);
+		usbtmc_ioctl_cancel_io(file_data);
+	}
+
+	return 0;
+}
+
+static int usbtmc_post_reset(struct usb_interface *intf)
+{
+	struct usbtmc_device_data *data  = usb_get_intfdata(intf);
+
+	mutex_unlock(&data->io_mutex);
+
+	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,
+	.pre_reset	= usbtmc_pre_reset,
+	.post_reset	= usbtmc_post_reset,
+	.dev_groups	= usbtmc_groups,
+};
+
+module_usb_driver(usbtmc_driver);
+
+MODULE_LICENSE("GPL");