Staging: add frontier tranzport and alphatrack drivers

Adds the tranzport and alphatrack drivers to the staging tree.

Cc: David Taht <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/Kconfig

···
 
 source "drivers/staging/mimio/Kconfig"
 
+source "drivers/staging/frontier/Kconfig"
+
 endif # !STAGING_EXCLUDE_BUILD
 endif # STAGING

drivers/staging/Makefile

···
 obj-$(CONFIG_RTL8187SE)		+= rtl8187se/
 obj-$(CONFIG_USB_RSPI)		+= rspiusb/
 obj-$(CONFIG_INPUT_MIMIO)	+= mimio/
+obj-$(CONFIG_TRANZPORT)		+= frontier/

drivers/staging/frontier/Kconfig

···
+config TRANZPORT
+	tristate "Frontier Tranzport and Alphatrack support"
+	depends on USB
+	default N
+	---help---
+	  Enable support for the Frontier Tranzport and Alphatrack devices.

drivers/staging/frontier/Makefile

···
+obj-$(CONFIG_TRANZPORT)		+= tranzport.o
+obj-$(CONFIG_TRANZPORT)		+= alphatrack.o

drivers/staging/frontier/README

···
+This directory contains the USB Tranzport and Alphatrack Kernel drivers for Linux.
+
+At present the tranzport does reads/writes of 8 byte cmds to /dev/tranzport0 to control
+the lights and screen and wheel
+
+At present the alphatrack accepts reads/writes of 12 byte cmds to /dev/tranzport0 to control
+the lights and screen and fader.
+
+Both drivers also have some sysfs hooks that are non-functional at the moment.
+
+The API is currently closely tied to the ardour revision and WILL change.
+
+A sysfs interface is PERFECT for simple userspace apps to do fun things with the
+lights and screen. It's fairly lousy for handling input events and very lousy
+for watching the state of the shuttle wheel.
+
+A linux input events interface is great for the input events and shuttle wheel. It's
+theoretically OK on LEDs. A Fader can be mapped to an absolute mouse device.
+But there is no LCD support at all.
+
+In the end this is going to be driven by a midi layer, which handles all those
+cases via a defined API, but - among other things - is slow, doesn't do
+flow control, and is a LOT of extra work. Frankly, I'd like to keep the
+core driver simple because the only realtime work really required is
+the bottom half interrupt handler and the output overlapping.
+
+Exposing some sort of clean aio api to userspace would be perfect. What that
+API looks like? Gah. beats me.

drivers/staging/frontier/TODO

···
+TODO:
+	- checkpatch.pl clean
+	- sparse clean
+	- fix userspace interface to be sane
+	- possibly just port to userspace with libusb
+	- review by the USB developer community
+
+Please send any patches for this driver to Greg Kroah-Hartman <[e-mail]>
+and David Taht <[e-mail]>.

drivers/staging/frontier/alphatrack.c

···
+/*
+ * Frontier Designs Alphatrack driver
+ *
+ * Copyright (C) 2007 Michael Taht ([e-mail])
+ *
+ * Based on the usbled driver and ldusb drivers by
+ *
+ * Copyright (C) 2004 Greg Kroah-Hartman ([e-mail])
+ * Copyright (C) 2005 Michael Hund <[e-mail]>
+ *
+ * The ldusb driver was, in turn, derived from Lego USB Tower driver
+ * Copyright (C) 2003 David Glance <[e-mail]>
+ *		 2001-2004 Juergen Stuber <[e-mail]>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License as
+ *	published by the Free Software Foundation, version 2.
+ *
+ */
+
+/**
+ * This driver uses a ring buffer for time critical reading of
+ * interrupt in reports and provides read and write methods for
+ * raw interrupt reports.
+ */
+
+/* Note: this currently uses a dumb ringbuffer for reads and writes.
+ * A more optimal driver would cache and kill off outstanding urbs that are
+ * now invalid, and ignore ones that already were in the queue but valid
+ * as we only have 30 commands for the alphatrack. In particular this is
+ * key for getting lights to flash in time as otherwise many commands
+ * can be buffered up before the light change makes it to the interface.
+*/
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include <linux/mutex.h>
+#include <linux/version.h>
+
+#include <asm/uaccess.h>
+#include <linux/input.h>
+#include <linux/usb.h>
+#include <linux/poll.h>
+
+#include "surface_sysfs.h"
+
+/* make this work on older kernel versions */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 19)
+#include "frontier_compat.h"
+#endif /* older kernel versions */
+
+#include "alphatrack.h"
+
+#define VENDOR_ID	0x165b
+#define PRODUCT_ID	0xfad1
+
+#ifdef CONFIG_USB_DYNAMIC_MINORS
+#define USB_ALPHATRACK_MINOR_BASE	0
+#else
+// FIXME 176 - is another driver's minor - apply for that
+// #define USB_ALPHATRACK_MINOR_BASE	177
+#define USB_ALPHATRACK_MINOR_BASE	176
+#endif
+
+/* table of devices that work with this driver */
+static struct usb_device_id usb_alphatrack_table [] = {
+	{ USB_DEVICE(VENDOR_ID, PRODUCT_ID) },
+	{ }					/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, usb_alphatrack_table);
+MODULE_VERSION("0.40");
+MODULE_AUTHOR("Mike Taht <[e-mail]>");
+MODULE_DESCRIPTION("Alphatrack USB Driver");
+MODULE_LICENSE("GPL");
+MODULE_SUPPORTED_DEVICE("Frontier Designs Alphatrack Control Surface");
+
+/* These aren't done yet */
+
+#define ALPHATRACK_HAVE_SYSFS 0
+#define SUPPRESS_EXTRA_ONLINE_EVENTS 0
+#define BUFFERED_WRITES 0
+#define SUPPRESS_EXTRA_OFFLINE_EVENTS 0
+#define COMPRESS_FADER_EVENTS 0
+
+#define BUFFERED_READS 1
+#define RING_BUFFER_SIZE 512
+#define WRITE_BUFFER_SIZE 34
+#define ALPHATRACK_USB_TIMEOUT 10
+#define OUTPUT_CMD_SIZE 8
+#define INPUT_CMD_SIZE 12
+
+
+static int debug = 0;
+
+/* Use our own dbg macro */
+#define dbg_info(dev, format, arg...) do { if (debug) dev_info(dev , format , ## arg); } while (0)
+
+#if 0
+#define alphatrack_ocmd_info(dev, cmd, format, arg...) do { if (debug) ocmd_info(dev , cmd , format, ## arg); } while (0)
+
+#define alphatrack_icmd_info(dev, cmd, format, arg...) do { if (debug) icmd_info(dev , cmd, format, ## arg); } while (0)
+#else
+#define alphatrack_ocmd_info(dev, cmd, format, arg...)
+
+#define alphatrack_icmd_info(dev, cmd, format, arg...)
+
+#endif
+
+/* Module parameters */
+
+module_param(debug, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug enabled or not");
+
+/* All interrupt in transfers are collected in a ring buffer to
+ * avoid racing conditions and get better performance of the driver.
+ */
+
+static int ring_buffer_size = RING_BUFFER_SIZE;
+
+module_param(ring_buffer_size, int,  S_IRUGO);
+MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size");
+
+/* The write_buffer can one day contain more than one interrupt out transfer.
+ */
+
+static int write_buffer_size = WRITE_BUFFER_SIZE;
+module_param(write_buffer_size, int,  S_IRUGO);
+MODULE_PARM_DESC(write_buffer_size, "Write buffer size");
+
+/*
+ * Increase the interval for debugging purposes.
+ * or set to 1 to use the standard interval from the endpoint descriptors.
+ */
+
+static int min_interrupt_in_interval = ALPHATRACK_USB_TIMEOUT;
+module_param(min_interrupt_in_interval, int, 0);
+MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");
+
+static int min_interrupt_out_interval = ALPHATRACK_USB_TIMEOUT;
+module_param(min_interrupt_out_interval, int, 0);
+MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");
+
+
+
+/* Structure to hold all of our device specific stuff */
+
+struct usb_alphatrack {
+	struct semaphore	sem;		/* locks this structure */
+	struct usb_interface*	intf;		/* save off the usb interface pointer */
+	int			open_count;	/* number of times this port has been opened */
+
+	struct alphatrack_icmd	(*ring_buffer)[RING_BUFFER_SIZE]; /* just make c happy */
+	struct alphatrack_ocmd	(*write_buffer)[WRITE_BUFFER_SIZE]; /* just make c happy */
+	unsigned int		ring_head;
+	unsigned int		ring_tail;
+
+	wait_queue_head_t	read_wait;
+	wait_queue_head_t	write_wait;
+
+	unsigned char*		interrupt_in_buffer;
+	unsigned char*		oldi_buffer;
+	struct usb_endpoint_descriptor* interrupt_in_endpoint;
+	struct urb*		interrupt_in_urb;
+	int			interrupt_in_interval;
+	size_t			interrupt_in_endpoint_size;
+	int			interrupt_in_running;
+	int			interrupt_in_done;
+
+	char*			interrupt_out_buffer;
+	struct usb_endpoint_descriptor* interrupt_out_endpoint;
+	struct urb*		interrupt_out_urb;
+	int			interrupt_out_interval;
+	size_t			interrupt_out_endpoint_size;
+	int			interrupt_out_busy;
+
+	atomic_t writes_pending;
+	int event; /* alternate interface to events */
+	int fader; /* 10 bits */
+	int lights; /* 23 bits */
+	unsigned char dump_state; /* 0 if disabled 1 if enabled */
+	unsigned char enable; /* 0 if disabled 1 if enabled */
+	unsigned char offline; /* if the device is out of range or asleep */
+	unsigned char verbose; /* be verbose in error reporting */
+	unsigned char  last_cmd[OUTPUT_CMD_SIZE];
+	unsigned char  screen[32];
+};
+
+/* prevent races between open() and disconnect() */
+static DEFINE_MUTEX(disconnect_mutex);
+
+/* forward declaration */
+
+static struct usb_driver usb_alphatrack_driver;
+
+static void icmd_info(struct usb_alphatrack *dev, char *cmd, char *str, char *a) {
+/*
+if (dev->verbose) {
+} else {
+}
+*/
+}
+
+static void ocmd_info(struct usb_alphatrack *dev, char *cmd, char *str, char* a) {
+/*
+if (dev->verbose) {
+} else {
+}
+*/
+}
+
+
+/**
+ *	usb_alphatrack_abort_transfers
+ *      aborts transfers and frees associated data structures
+ */
+static void usb_alphatrack_abort_transfers(struct usb_alphatrack *dev)
+{
+	/* shutdown transfer */
+	if (dev->interrupt_in_running) {
+		dev->interrupt_in_running = 0;
+		if (dev->intf)
+			usb_kill_urb(dev->interrupt_in_urb);
+	}
+	if (dev->interrupt_out_busy)
+		if (dev->intf)
+			usb_kill_urb(dev->interrupt_out_urb);
+}
+
+#if ALPHATRACK_HAVE_SYSFS
+/* lots and lots and lots of sysfs stuff */
+/* Currently borked, probably useless */
+#include "alphatrack_sysfs.c"
+#endif
+
+/**
+ *	usb_alphatrack_delete
+ */
+static void usb_alphatrack_delete(struct usb_alphatrack *dev)
+{
+	usb_alphatrack_abort_transfers(dev);
+	usb_free_urb(dev->interrupt_in_urb);
+	usb_free_urb(dev->interrupt_out_urb);
+	kfree(dev->ring_buffer);
+	kfree(dev->interrupt_in_buffer);
+	kfree(dev->interrupt_out_buffer);
+	kfree(dev); // fixme oldi_buffer
+}
+
+/**
+ *	usb_alphatrack_interrupt_in_callback
+ */
+
+static void usb_alphatrack_interrupt_in_callback(struct urb *urb)
+{
+	struct usb_alphatrack *dev = urb->context;
+	unsigned int next_ring_head;
+	int retval = -1;
+	int *iptr;
+
+	if (urb->status) {
+		if (urb->status == -ENOENT ||
+		    urb->status == -ECONNRESET ||
+		    urb->status == -ESHUTDOWN) {
+			goto exit;
+		} else {
+			dbg_info(&dev->intf->dev, "%s: nonzero status received: %d\n",
+				 __FUNCTION__, urb->status);
+			goto resubmit; /* maybe we can recover */
+		}
+	}
+
+	if (urb->actual_length != INPUT_CMD_SIZE) {
+		dev_warn(&dev->intf->dev,
+			 "Urb length was %d bytes!! Do something intelligent \n", urb->actual_length);
+	} else {
+		 alphatrack_ocmd_info(&dev->intf->dev,&(*dev->ring_buffer)[dev->ring_tail].cmd,"%s", "bla");
+		 if(memcmp(dev->interrupt_in_buffer,dev->oldi_buffer,INPUT_CMD_SIZE)==0) {
+						goto resubmit;
+		}
+		memcpy(dev->oldi_buffer,dev->interrupt_in_buffer,INPUT_CMD_SIZE);
+
+#if SUPPRESS_EXTRA_OFFLINE_EVENTS
+	if(dev->offline == 2 && dev->interrupt_in_buffer[1] == 0xff) { goto resubmit; }
+		if(dev->offline == 1 && dev->interrupt_in_buffer[1] == 0xff) { dev->offline = 2; goto resubmit; }
+/* Always pass one offline event up the stack */
+		if(dev->offline > 0 && dev->interrupt_in_buffer[1] != 0xff) { dev->offline = 0; }
+		if(dev->offline == 0 && dev->interrupt_in_buffer[1] == 0xff) { dev->offline = 1; }
+#endif
+		dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n", __FUNCTION__,dev->ring_head,dev->ring_tail);
+		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
+
+		if (next_ring_head != dev->ring_tail) {
+			memcpy(&((*dev->ring_buffer)[dev->ring_head]),
+						 dev->interrupt_in_buffer, urb->actual_length);
+			dev->ring_head = next_ring_head;
+			retval = 0;
+			memset(dev->interrupt_in_buffer, 0, urb->actual_length);
+		} else {
+			dev_warn(&dev->intf->dev,
+				 "Ring buffer overflow, %d bytes dropped\n",
+				 urb->actual_length);
+			memset(dev->interrupt_in_buffer, 0, urb->actual_length);
+		}
+	}
+
+resubmit:
+	/* resubmit if we're still running */
+	if (dev->interrupt_in_running && dev->intf) {
+		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
+		if (retval)
+			dev_err(&dev->intf->dev,
+				"usb_submit_urb failed (%d)\n", retval);
+	}
+
+exit:
+	dev->interrupt_in_done = 1;
+	wake_up_interruptible(&dev->read_wait);
+}
+
+/**
+ *	usb_alphatrack_interrupt_out_callback
+ */
+static void usb_alphatrack_interrupt_out_callback(struct urb *urb)
+{
+	struct usb_alphatrack *dev = urb->context;
+
+	/* sync/async unlink faults aren't errors */
+	if (urb->status && !(urb->status == -ENOENT ||
+			     urb->status == -ECONNRESET ||
+			     urb->status == -ESHUTDOWN))
+		dbg_info(&dev->intf->dev,
+			 "%s - nonzero write interrupt status received: %d\n",
+			 __FUNCTION__, urb->status);
+	atomic_dec(&dev->writes_pending);
+	dev->interrupt_out_busy = 0;
+	wake_up_interruptible(&dev->write_wait);
+}
+
+/**
+ *	usb_alphatrack_open
+ */
+static int usb_alphatrack_open(struct inode *inode, struct file *file)
+{
+	struct usb_alphatrack *dev;
+	int subminor;
+	int retval = 0;
+	struct usb_interface *interface;
+
+	nonseekable_open(inode, file);
+	subminor = iminor(inode);
+
+	mutex_lock(&disconnect_mutex);
+
+	interface = usb_find_interface(&usb_alphatrack_driver, subminor);
+
+	if (!interface) {
+		err("%s - error, can't find device for minor %d\n",
+		     __FUNCTION__, subminor);
+		retval = -ENODEV;
+		goto unlock_disconnect_exit;
+	}
+
+	dev = usb_get_intfdata(interface);
+
+	if (!dev) {
+		retval = -ENODEV;
+		goto unlock_disconnect_exit;
+	}
+
+	/* lock this device */
+	if (down_interruptible(&dev->sem)) {
+		retval = -ERESTARTSYS;
+		goto unlock_disconnect_exit;
+	}
+
+	/* allow opening only once */
+	if (dev->open_count) {
+		retval = -EBUSY;
+		goto unlock_exit;
+	}
+	dev->open_count = 1;
+
+	/* initialize in direction */
+	dev->ring_head = 0;
+	dev->ring_tail = 0;
+	usb_fill_int_urb(dev->interrupt_in_urb,
+			 interface_to_usbdev(interface),
+			 usb_rcvintpipe(interface_to_usbdev(interface),
+					dev->interrupt_in_endpoint->bEndpointAddress),
+			 dev->interrupt_in_buffer,
+			 dev->interrupt_in_endpoint_size,
+			 usb_alphatrack_interrupt_in_callback,
+			 dev,
+			 dev->interrupt_in_interval);
+
+	dev->interrupt_in_running = 1;
+	dev->interrupt_in_done = 0;
+	dev->enable = 1;
+	dev->offline = 0;
+
+	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
+	if (retval) {
+		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
+		dev->interrupt_in_running = 0;
+		dev->open_count = 0;
+		goto unlock_exit;
+	}
+
+	/* save device in the file's private structure */
+	file->private_data = dev;
+
+
+unlock_exit:
+	up(&dev->sem);
+
+unlock_disconnect_exit:
+	mutex_unlock(&disconnect_mutex);
+
+	return retval;
+}
+
+/**
+ *	usb_alphatrack_release
+ */
+static int usb_alphatrack_release(struct inode *inode, struct file *file)
+{
+	struct usb_alphatrack *dev;
+	int retval = 0;
+
+	dev = file->private_data;
+
+	if (dev == NULL) {
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	if (down_interruptible(&dev->sem)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	if (dev->open_count != 1) {
+		retval = -ENODEV;
+		goto unlock_exit;
+	}
+
+	if (dev->intf == NULL) {
+		/* the device was unplugged before the file was released */
+		up(&dev->sem);
+		/* unlock here as usb_alphatrack_delete frees dev */
+		usb_alphatrack_delete(dev);
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	/* wait until write transfer is finished */
+	if (dev->interrupt_out_busy)
+		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
+	usb_alphatrack_abort_transfers(dev);
+	dev->open_count = 0;
+
+unlock_exit:
+	up(&dev->sem);
+
+exit:
+	return retval;
+}
+
+/**
+ *	usb_alphatrack_poll
+ */
+static unsigned int usb_alphatrack_poll(struct file *file, poll_table *wait)
+{
+	struct usb_alphatrack *dev;
+	unsigned int mask = 0;
+
+	dev = file->private_data;
+
+	poll_wait(file, &dev->read_wait, wait);
+	poll_wait(file, &dev->write_wait, wait);
+
+	if (dev->ring_head != dev->ring_tail)
+		mask |= POLLIN | POLLRDNORM;
+	if (!dev->interrupt_out_busy)
+		mask |= POLLOUT | POLLWRNORM;
+
+	return mask;
+}
+
+/**
+ *	usb_alphatrack_read
+ */
+static ssize_t usb_alphatrack_read(struct file *file, char __user *buffer, size_t count,
+			   loff_t *ppos)
+{
+	struct usb_alphatrack *dev;
+	int retval = 0;
+
+	int c = 0;
+
+	dev = file->private_data;
+
+	/* verify that we actually have some data to read */
+	if (count == 0)
+		goto exit;
+
+	/* lock this object */
+	if (down_interruptible(&dev->sem)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	/* verify that the device wasn't unplugged */
+	if (dev->intf == NULL) {
+		retval = -ENODEV;
+		err("No device or device unplugged %d\n", retval);
+		goto unlock_exit;
+	}
+
+	while (dev->ring_head == dev->ring_tail) {
+					if (file->f_flags & O_NONBLOCK) {
+									retval = -EAGAIN;
+									goto unlock_exit;
+					}
+					dev->interrupt_in_done = 0 ;
+					retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
+					if (retval < 0) {
+									goto unlock_exit;
+					}
+	}
+
+	alphatrack_ocmd_info(&dev->intf->dev, &(*dev->ring_buffer)[dev->ring_tail].cmd, "%s", ": copying to userspace");
+
+	   c = 0;
+	   while((c < count) && (dev->ring_tail != dev->ring_head)) {
+						 if (copy_to_user(&buffer[c], &(*dev->ring_buffer)[dev->ring_tail], INPUT_CMD_SIZE)) {
+										 retval = -EFAULT;
+										 goto unlock_exit;
+						 }
+						 dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
+						 c+=INPUT_CMD_SIZE;
+						 dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n", __FUNCTION__,dev->ring_head,dev->ring_tail);
+	   }
+	   retval = c;
+
+unlock_exit:
+	/* unlock the device */
+	up(&dev->sem);
+
+exit:
+	return retval;
+}
+
+/**
+ *	usb_alphatrack_write
+ */
+static ssize_t usb_alphatrack_write(struct file *file, const char __user *buffer,
+			    size_t count, loff_t *ppos)
+{
+	struct usb_alphatrack *dev;
+	size_t bytes_to_write;
+	int retval = 0;
+
+	dev = file->private_data;
+
+	/* verify that we actually have some data to write */
+	if (count == 0)
+		goto exit;
+
+	/* lock this object */
+	if (down_interruptible(&dev->sem)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	/* verify that the device wasn't unplugged */
+	if (dev->intf == NULL) {
+		retval = -ENODEV;
+		err("No device or device unplugged %d\n", retval);
+		goto unlock_exit;
+	}
+
+	/* wait until previous transfer is finished */
+	if (dev->interrupt_out_busy) {
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto unlock_exit;
+		}
+		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
+		if (retval < 0) {
+			goto unlock_exit;
+		}
+	}
+
+	/* write the data into interrupt_out_buffer from userspace */
+  /* FIXME - if you write more than 12 bytes this breaks */
+	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
+	if (bytes_to_write < count)
+		dev_warn(&dev->intf->dev, "Write buffer overflow, %zd bytes dropped\n",count-bytes_to_write);
+
+	dbg_info(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n", __FUNCTION__, count, bytes_to_write);
+
+	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
+		retval = -EFAULT;
+		goto unlock_exit;
+	}
+
+	if (dev->interrupt_out_endpoint == NULL) {
+		err("Endpoint should not be be null! \n");
+		goto unlock_exit;
+	}
+
+	/* send off the urb */
+	usb_fill_int_urb(dev->interrupt_out_urb,
+			 interface_to_usbdev(dev->intf),
+			 usb_sndintpipe(interface_to_usbdev(dev->intf),
+					dev->interrupt_out_endpoint->bEndpointAddress),
+			 dev->interrupt_out_buffer,
+			 bytes_to_write,
+			 usb_alphatrack_interrupt_out_callback,
+			 dev,
+			 dev->interrupt_out_interval);
+	dev->interrupt_out_busy = 1;
+	atomic_inc(&dev->writes_pending);
+	wmb();
+
+	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
+	if (retval) {
+		dev->interrupt_out_busy = 0;
+		err("Couldn't submit interrupt_out_urb %d\n", retval);
+		atomic_dec(&dev->writes_pending);
+		goto unlock_exit;
+	}
+	retval = bytes_to_write;
+
+unlock_exit:
+	/* unlock the device */
+	up(&dev->sem);
+
+exit:
+	return retval;
+}
+
+/* file operations needed when we register this driver */
+static const struct file_operations usb_alphatrack_fops = {
+	.owner =	THIS_MODULE,
+	.read  =	usb_alphatrack_read,
+	.write =	usb_alphatrack_write,
+	.open =		usb_alphatrack_open,
+	.release =	usb_alphatrack_release,
+	.poll =		usb_alphatrack_poll,
+};
+
+/*
+ * usb class driver info in order to get a minor number from the usb core,
+ * and to have the device registered with the driver core
+ */
+
+static struct usb_class_driver usb_alphatrack_class = {
+	.name =		"alphatrack%d",
+	.fops =		&usb_alphatrack_fops,
+	.minor_base =	USB_ALPHATRACK_MINOR_BASE,
+};
+
+
+/**
+ *	usb_alphatrack_probe
+ *
+ *	Called by the usb core when a new device is connected that it thinks
+ *	this driver might be interested in.
+ */
+static int usb_alphatrack_probe(struct usb_interface *intf, const struct usb_device_id *id)
+{
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct usb_alphatrack *dev = NULL;
+	struct usb_host_interface *iface_desc;
+	struct usb_endpoint_descriptor *endpoint;
+	int i;
+	int true_size;
+	int retval = -ENOMEM;
+
+	/* allocate memory for our device state and intialize it */
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (dev == NULL) {
+		dev_err(&intf->dev, "Out of memory\n");
+		goto exit;
+	}
+	init_MUTEX(&dev->sem);
+	dev->intf = intf;
+	init_waitqueue_head(&dev->read_wait);
+	init_waitqueue_head(&dev->write_wait);
+
+	iface_desc = intf->cur_altsetting;
+
+	/* set up the endpoint information */
+	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
+		endpoint = &iface_desc->endpoint[i].desc;
+
+		if (usb_endpoint_is_int_in(endpoint))
+			dev->interrupt_in_endpoint = endpoint;
+
+		if (usb_endpoint_is_int_out(endpoint))
+			dev->interrupt_out_endpoint = endpoint;
+	}
+	if (dev->interrupt_in_endpoint == NULL) {
+		dev_err(&intf->dev, "Interrupt in endpoint not found\n");
+		goto error;
+	}
+	if (dev->interrupt_out_endpoint == NULL)
+		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");
+
+	dev->interrupt_in_endpoint_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
+
+	if (dev->interrupt_in_endpoint_size != 64)
+	    dev_warn(&intf->dev, "Interrupt in endpoint size is not 64!\n");
+
+	if(ring_buffer_size == 0) { ring_buffer_size = RING_BUFFER_SIZE; }
+
+	true_size = min(ring_buffer_size,RING_BUFFER_SIZE);
+
+	/* FIXME - there are more usb_alloc routines for dma correctness. Needed? */
+
+//	dev->ring_buffer = kmalloc((true_size*sizeof(struct alphatrack_icmd))+12, GFP_KERNEL);
+	dev->ring_buffer = kmalloc((true_size*sizeof(struct alphatrack_icmd)), GFP_KERNEL);
+
+	if (!dev->ring_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate input ring_buffer of size %d\n",true_size);
+		goto error;
+	}
+
+	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
+
+	if (!dev->interrupt_in_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
+		goto error;
+	}
+	dev->oldi_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
+	if (!dev->oldi_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate old buffer\n");
+		goto error;
+	}
+	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->interrupt_in_urb) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
+		goto error;
+	}
+
+	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize) :
+									 udev->descriptor.bMaxPacketSize0;
+
+	if (dev->interrupt_out_endpoint_size !=64)
+		dev_warn(&intf->dev, "Interrupt out endpoint size is not 64!)\n");
+
+	if(write_buffer_size == 0) { write_buffer_size = WRITE_BUFFER_SIZE; }
+	true_size = min(write_buffer_size,WRITE_BUFFER_SIZE);
+
+	dev->interrupt_out_buffer = kmalloc(true_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
+
+	if (!dev->interrupt_out_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_out_buffer\n");
+		goto error;
+	}
+
+	dev->write_buffer = kmalloc(sizeof(struct alphatrack_ocmd)*true_size, GFP_KERNEL);
+
+	if (!dev->write_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate write_buffer \n");
+		goto error;
+	}
+
+	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->interrupt_out_urb) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
+		goto error;
+	}
+	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
+	if (dev->interrupt_out_endpoint)
+		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
+
+	/* we can register the device now, as it is ready */
+	usb_set_intfdata(intf, dev);
+
+	atomic_set(&dev->writes_pending,0);
+	retval = usb_register_dev(intf, &usb_alphatrack_class);
+	if (retval) {
+		/* something prevented us from registering this driver */
+		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
+		usb_set_intfdata(intf, NULL);
+		goto error;
+	}
+
+	/* let the user know what node this device is now attached to */
+	dev_info(&intf->dev, "Alphatrack Device #%d now attached to major %d minor %d\n",
+		(intf->minor - USB_ALPHATRACK_MINOR_BASE), USB_MAJOR, intf->minor);
+
+#if ALPHATRACK_HAVE_SYSFS
+	if((retval = device_create_file(&intf->dev, &dev_attr_event))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_dump_state))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_enable))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_offline))) goto error;
+
+  /* exercise sysfs */
+
+	set_lights("32767"); // turn on all the lights
+	set_fader0("1023"); // Move fader to max
+	set_screen("INITIALIZING               ALPHATRACK...");
+	set_lights("0");
+	set_fader0("0");
+	set_screen("                                        ");
+
+#endif
+
+exit:
+	return retval;
+
+error:
+	usb_alphatrack_delete(dev);
+
+	return retval;
+}
+
+/**
+ *	usb_alphatrack_disconnect
+ *
+ *	Called by the usb core when the device is removed from the system.
+ */
+static void usb_alphatrack_disconnect(struct usb_interface *intf)
+{
+	struct usb_alphatrack *dev;
+	int minor;
+
+	mutex_lock(&disconnect_mutex);
+
+	dev = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, NULL);
+
+	down(&dev->sem);
+
+	minor = intf->minor;
+
+	/* give back our minor */
+	usb_deregister_dev(intf, &usb_alphatrack_class);
+
+	/* if the device is not opened, then we clean up right now */
+	if (!dev->open_count) {
+		up(&dev->sem);
+		usb_alphatrack_delete(dev);
+	} else {
+		dev->intf = NULL;
+		up(&dev->sem);
+	}
+
+	atomic_set(&dev->writes_pending,0);
+	mutex_unlock(&disconnect_mutex);
+
+	dev_info(&intf->dev, "Alphatrack Surface #%d now disconnected\n",
+		 (minor - USB_ALPHATRACK_MINOR_BASE));
+}
+
+/* usb specific object needed to register this driver with the usb subsystem */
+static struct usb_driver usb_alphatrack_driver = {
+	.name =		"alphatrack",
+	.probe =	usb_alphatrack_probe,
+	.disconnect =	usb_alphatrack_disconnect,
+	.id_table =	usb_alphatrack_table,
+};
+
+/**
+ *	usb_alphatrack_init
+ */
+static int __init usb_alphatrack_init(void)
+{
+	int retval;
+
+	/* register this driver with the USB subsystem */
+	retval = usb_register(&usb_alphatrack_driver);
+	if (retval)
+		err("usb_register failed for the "__FILE__" driver. Error number %d\n", retval);
+
+	return retval;
+}
+
+/**
+ *	usb_alphatrack_exit
+ */
+static void __exit usb_alphatrack_exit(void)
+{
+	/* deregister this driver with the USB subsystem */
+	usb_deregister(&usb_alphatrack_driver);
+}
+
+module_init(usb_alphatrack_init);
+module_exit(usb_alphatrack_exit);
+

drivers/staging/frontier/alphatrack.h

···
+#define show_set_bit(a) show_set_mbit(alphatrack,a)
+#define show_set_cmd(a) show_set_mcmd(alphatrack,a)
+#define show_set_int(a) show_set_mint(alphatrack,a)
+#define show_set_char(a) show_set_mchar(alphatrack,a)
+#define show_set_light(a) show_set_ebit(alphatrack,LightID,lights,a)
+#define show_set_button(a) show_set_ebit(alphatrack,ButtonID,button,a)
+
+struct alphatrack_icmd {
+    unsigned char cmd[12];
+};
+
+struct alphatrack_ocmd {
+    unsigned char cmd[8];
+};
+
+enum LightID {
+        LIGHT_EQ = 0,
+        LIGHT_OUT,
+        LIGHT_F2,
+        LIGHT_SEND,
+        LIGHT_IN,
+        LIGHT_F1,
+        LIGHT_PAN,
+        LIGHT_UNDEF1,
+        LIGHT_UNDEF2,
+        LIGHT_SHIFT,
+        LIGHT_TRACKMUTE,
+        LIGHT_TRACKSOLO,
+        LIGHT_TRACKREC,
+        LIGHT_READ,
+        LIGHT_WRITE,
+        LIGHT_ANYSOLO,
+        LIGHT_AUTO,
+        LIGHT_F4,
+        LIGHT_RECORD,
+        LIGHT_WINDOW,
+        LIGHT_PLUGIN,
+        LIGHT_F3,
+        LIGHT_LOOP
+};
+
+static const char *Lightname[] = { "eq",
+"out",
+"f2",
+"send",
+"in",
+"f1",
+"pan",
+"undef1",
+"undef2",
+"shift",
+"mute",
+"tracksolo",
+"trackrec",
+"read",
+"write",
+"anysolo",
+"auto",
+"f4",
+"record",
+"window",
+"plugin",
+"f3",
+"loop",
+NULL };
+
+#define BUTTONMASK_BATTERY     0x00004000
+#define BUTTONMASK_BACKLIGHT   0x00008000
+#define BUTTONMASK_FASTFORWARD 0x04000000
+#define BUTTONMASK_TRACKMUTE   0x00040000
+#define BUTTONMASK_TRACKSOLO   0x00800000
+#define BUTTONMASK_TRACKLEFT   0x80000000
+#define BUTTONMASK_RECORD      0x02000000
+#define BUTTONMASK_SHIFT       0x20000000
+#define BUTTONMASK_PUNCH       0x00800000
+#define BUTTONMASK_TRACKRIGHT  0x00020000
+#define BUTTONMASK_REWIND      0x01000000
+#define BUTTONMASK_STOP        0x10000000
+#define BUTTONMASK_LOOP        0x00010000
+#define BUTTONMASK_TRACKREC    0x00001000
+#define BUTTONMASK_PLAY        0x08000000
+#define BUTTONMASK_TOUCH1      0x00000008
+#define BUTTONMASK_TOUCH2      0x00000010
+#define BUTTONMASK_TOUCH3      0x00000020
+
+#define BUTTONMASK_PRESS1      0x00000009
+#define BUTTONMASK_PRESS2      0x00008010
+#define BUTTONMASK_PRESS3      0x00002020
+
+// last 3 bytes are the slider position
+// 40 is the actual slider moving, the most sig bits, and 3 lsb
+
+#define BUTTONMASK_FLIP         0x40000000
+#define BUTTONMASK_F1           0x00100000
+#define BUTTONMASK_F2           0x00400000
+#define BUTTONMASK_F3           0x00200000
+#define BUTTONMASK_F4           0x00080000
+#define BUTTONMASK_PAN          0x00000200
+#define BUTTONMASK_SEND         0x00000800
+#define BUTTONMASK_EQ           0x00004000
+#define BUTTONMASK_PLUGIN       0x00000400
+#define BUTTONMASK_AUTO         0x00000100
+
+
+// #define BUTTONMASK_FOOTSWITCH FIXME
+
+// Lookup. name. midi out. midi in.
+
+struct buttonmap_t {
+	u32 mask;
+	short midi_in;
+	short midi_out;
+	char *name;
+//  	void (*function) (buttonmap_t *);
+  	void (*function) (void);
+};
+

drivers/staging/frontier/alphatrack_sysfs.c

···
+/* This was an attempt - ultimately proved pointless - at making a full fledged sysfs interface to the alphatrack */
+/* won't even compile at present */
+
+char *alphatrack_sys_margs;
+spinlock_t alphatrack_sys_margs_lock;
+
+struct alphatrack_attr {
+        struct attribute attr;
+        ssize_t (*show)(struct device *, char *);
+        ssize_t (*store)(struct device *, const char *, size_t);
+};
+
+#define ALPHATRACK_ATTR(name, mode, show, store) \
+static struct alphatrack_attr alphatrack_attr_##name = __ATTR(name, mode, show, store)
+
+/* now a great deal of callback code generation */
+
+// FOREACH_LIGHT(show_set_light)
+// FOREACH_BUTTON(show_set_button)
+
+show_set_light(LIGHT_RECORD); show_set_light(LIGHT_EQ); show_set_light(LIGHT_OUT);
+show_set_light(LIGHT_F2); show_set_light(LIGHT_SEND);   show_set_light(LIGHT_IN);
+show_set_light(LIGHT_F1); show_set_light(LIGHT_PAN);    show_set_light(LIGHT_UNDEF1);
+show_set_light(LIGHT_UNDEF2); show_set_light(LIGHT_SHIFT); show_set_light(LIGHT_TRACKMUTE);
+show_set_light(LIGHT_TRACKSOLO); show_set_light(LIGHT_TRACKREC); show_set_light(LIGHT_READ);
+show_set_light(LIGHT_WRITE); show_set_light(LIGHT_ANYSOLO); show_set_light(LIGHT_AUTO);
+show_set_light(LIGHT_F4); show_set_light(LIGHT_RECORD); show_set_light(LIGHT_WINDOW);
+show_set_light(LIGHT_PLUGIN); show_set_light(LIGHT_F3); show_set_light(LIGHT_LOOP);
+
+show_set_opt(enable); show_set_opt(offline); show_set_opt(compress_fader); show_set_opt(dump_state);
+show_set_int(fader); show_set_int(event);
+
+
+static ssize_t show_lights(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct usb_alphatrack *t = usb_get_intfdata(intf);
+	return sprintf(buf, "%d\n", t->lights);
+}
+
+static ssize_t set_lights(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct usb_alphatrack *t = usb_get_intfdata(intf);
+	int temp = simple_strtoul(buf, NULL, 10);
+	t->lights = temp;
+	return count;
+}
+
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_lights, set_lights);
+
+
+ALPHATRACK_ATTR(LightRecord, 0200, NULL,          LightRecord_store);
+
+static struct attribute *alphatrack_attrs[] = {
+        &alphatrack_attr_LightRecord.attr,
+        NULL,
+};
+
+static ssize_t alphatrack_attr_show(struct kobject *kobj, struct attribute *attr,
+                              char *buf)
+{
+        struct device *sdp = container_of(kobj, struct device, kobj);
+        struct alphatrack_attr *a = container_of(attr, struct alphatrack_attr, attr);
+        return a->show ? a->show(sdp, buf) : 0;
+}
+
+static ssize_t alphatrack_attr_store(struct kobject *kobj, struct attribute *attr,
+                               const char *buf, size_t len)
+{
+        struct device *sdp = container_of(kobj, struct device, kobj);
+        struct alphatrack_attr *a = container_of(attr, struct alphatrack_attr, attr);
+        return a->store ? a->store(sdp, buf, len) : len;
+}
+
+static struct sysfs_ops alphatrack_attr_ops = {
+        .show  = alphatrack_attr_show,
+        .store = alphatrack_attr_store,
+};
+
+static struct kobj_type alphatrack_ktype = {
+        .default_attrs = alphatrack_attrs,
+        .sysfs_ops     = &alphatrack_attr_ops,
+};
+
+static struct kset alphatrack_kset = {
+        .subsys = &fs_subsys,
+        .kobj   = {.name = "alphatrack"},
+        .ktype  = &alphatrack_ktype,
+};
+
+
+static struct attribute *lights_attrs[] = {
+        &tune_attr_demote_secs.attr,
+        NULL,
+};
+
+
+static struct attribute_group leds_group = {
+        .name = "leds",
+        .attrs = lights_attrs,
+};
+
+static struct attribute_group faders_group = {
+        .name = "faders",
+        .attrs = faders_attrs,
+};
+
+static struct attribute_group lcds_group = {
+        .name = "lcds",
+        .attrs = lcds_attrs,
+};
+
+static struct attribute_group wheels_group = {
+        .name = "wheels",
+        .attrs = wheels_attrs,
+};
+
+static struct attribute_group touchsurfaces_group = {
+        .name = "touchsurfaces",
+        .attrs = touchsurfaces_attrs,
+};
+
+static struct attribute_group buttons_group = {
+        .name = "buttons",
+        .attrs = buttons_attrs,
+};
+
+
+int alphatrack_sys_fs_add(struct device *sdp)
+{
+        int error;
+
+        sdp->kobj.kset = &alphatrack_kset;
+        sdp->kobj.ktype = &alphatrack_ktype;
+
+//        error = kobject_set_name(&sdp->kobj, "%s", sdp->sd_table_name);
+        error = kobject_set_name(&sdp->kobj, "%s", "alphatrack");
+        if (error)
+                goto fail;
+
+        error = kobject_register(&sdp->kobj);
+        if (error)
+                goto fail;
+
+        error = sysfs_create_group(&sdp->kobj, &lcds_group);
+        if (error)
+                goto fail_reg;
+
+        error = sysfs_create_group(&sdp->kobj, &leds_group);
+        if (error)
+                goto fail_leds;
+
+        error = sysfs_create_group(&sdp->kobj, &wheels_group);
+        if (error)
+                goto fail_wheels;
+
+      error = sysfs_create_group(&sdp->kobj, &faders_group);
+        if (error)
+                goto fail_lcds;
+
+        error = sysfs_create_group(&sdp->kobj, &buttons_group);
+        if (error)
+                goto fail_faders;
+
+        error = sysfs_create_group(&sdp->kobj, &touchsurfaces_group);
+        if (error)
+                goto fail_buttons;
+
+        return 0;
+
+
+fail_buttons:
+        sysfs_remove_group(&sdp->kobj, &buttons_group);
+fail_faders:
+        sysfs_remove_group(&sdp->kobj, &faders_group);
+fail_wheels:
+        sysfs_remove_group(&sdp->kobj, &wheels_group);
+fail_lcds:
+        sysfs_remove_group(&sdp->kobj, &lcds_group);
+fail_leds:
+        sysfs_remove_group(&sdp->kobj, &leds_group);
+
+
+
+fail_reg:
+        kobject_unregister(&sdp->kobj);
+fail:
+        fs_err(sdp, "error %d adding sysfs files", error);
+        return error;
+}
+
+// int sysfs_create_link(struct kobject *kobj,
+//			  struct kobject *target,
+//			  char *name);
+
+void alphatrack_sys_fs_del(struct device *sdp)
+{
+        sysfs_remove_group(&sdp->kobj, &touchsurfaces_group);
+        sysfs_remove_group(&sdp->kobj, &buttons_group);
+        sysfs_remove_group(&sdp->kobj, &faders_group);
+        sysfs_remove_group(&sdp->kobj, &lcds_group);
+        sysfs_remove_group(&sdp->kobj, &wheels_group);
+        sysfs_remove_group(&sdp->kobj, &leds_group)
+//void sysfs_remove_link(struct kobject *kobj, char *name);
+					kobject_unregister(&sdp->kobj);
+}
+
+int alphatrack_sys_init(void)
+{
+        alphatrack_sys_margs = NULL;
+        spin_lock_init(&alphatrack_sys_margs_lock);
+        return kset_register(&alphatrack_kset);
+}
+
+void alphatrack_sys_uninit(void)
+{
+        kfree(alphatrack_sys_margs);
+        kset_unregister(&alphatrack_kset);
+}
+
+
+//decl_subsys(char *name, struct kobj_type *type,
+//                struct kset_hotplug_ops *hotplug_ops);
+
+/* End of all the crazy sysfs stuff */
+
+#define SYSEX_INQUIRE signed char *SYSEX_INQUIRE[] = { 0xf0,0x7e,0x00,0x06,0x01,0x17 };
+
+#define COMMAND(NAME,CONT_NAME)  { BUTTONMASK_##NAME, ((0x90 << 8) | CONT_NAME), ((0x90 << 8) | CONT_NAME), #NAME, NAME ## _set }
+#define ROTARY(NAME,CONT_NAME)  { FADER_##NAME, ((0xb0 << 8) | CONT_NAME), ((0xb0 << 8) | CONT_NAME), #NAME, NAME ## _set }
+#define SPOSITION(NAME,CONT_NAME)  { BUTTON_##NAME ((0xe9 << 8) | CONT_NAME), #NAME, NAME ## _set }
+#define ENDCOMMAND { 0,NULL,0,NULL,NULL}
+
+/* Now that we've generated all our callbacks */
+
+static struct buttonmap_t buttonmap[] =
+     {
+       COMMAND (REWIND,0x5b),
+       COMMAND (FASTFORWARD,0x5c),
+       COMMAND (STOP,0x5d),
+       COMMAND (PLAY,0x5e),
+       COMMAND (RECORD,0x5f),
+       COMMAND (SHIFT,0x46),
+       COMMAND (TRACKLEFT,0x57),
+       COMMAND (TRACKRIGHT,0x58),
+       COMMAND (LOOP,0x56),
+       COMMAND (FLIP,0x32),
+       COMMAND (MUTE,0x10),
+       COMMAND (F1,0x36),
+       COMMAND (F2,0x37),
+       COMMAND (F3,0x38),
+       COMMAND (F4,0x39),
+       COMMAND (SOLO,0x08),
+       COMMAND (ANY,0x73),
+       COMMAND (PAN,0x2a),
+       COMMAND (SEND,0x29),
+       COMMAND (EQ,0x2c),
+       COMMAND (PLUGIN,0x2b),
+       COMMAND (AUTO,0x4a),
+       COMMAND (TRACKREC,0x00),
+       COMMAND (FOOTSWITCH1,0x67),
+       COMMAND (KNOBTOUCH1,0x78),
+       COMMAND (KNOBPUSH1,0x20),
+       ROTARY  (KNOBTURN1,0x10),
+       COMMAND (KNOBTOUCH2,0x79),
+       COMMAND (KNOBPUSH2,0x21),
+       ROTARY  (KNOBTURN2,0x11),
+       COMMAND (KNOBTOUCH3,0x7a),
+       COMMAND (KNOBPUSH3,0x22),
+       ROTARY  (KNOBTURN3,0x12),
+       COMMAND (FADERTOUCH1,0x68),
+       COMMAND (STRIPTOUCH1,0x74),
+       COMMAND (STRIPTOUCH2,0x6b),
+       SPOSITION (STRIPPOS1,0x00),
+       ENDCOMMAND
+     };
+
+

drivers/staging/frontier/frontier_compat.h

···
+/* USB defines for older kernels */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 19)
+
+/**
+ * usb_endpoint_dir_out - check if the endpoint has OUT direction
+ * @epd: endpoint to be checked
+ *
+ * Returns true if the endpoint is of type OUT, otherwise it returns false.
+ */
+
+static inline int usb_endpoint_dir_out(const struct usb_endpoint_descriptor *epd)
+{
+       return ((epd->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT);
+}
+
+static inline int usb_endpoint_dir_in(const struct usb_endpoint_descriptor *epd)
+{
+       return ((epd->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_IN);
+}
+
+
+/**
+ * usb_endpoint_xfer_int - check if the endpoint has interrupt transfer type
+ * @epd: endpoint to be checked
+ *
+ * Returns true if the endpoint is of type interrupt, otherwise it returns
+ * false.
+ */
+static inline int usb_endpoint_xfer_int(const struct usb_endpoint_descriptor *epd)
+{
+       return ((epd->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
+               USB_ENDPOINT_XFER_INT);
+}
+
+
+/**
+ * usb_endpoint_is_int_in - check if the endpoint is interrupt IN
+ * @epd: endpoint to be checked
+ *
+ * Returns true if the endpoint has interrupt transfer type and IN direction,
+ * otherwise it returns false.
+ */
+
+static inline int usb_endpoint_is_int_in(const struct usb_endpoint_descriptor *epd)
+{
+       return (usb_endpoint_xfer_int(epd) && usb_endpoint_dir_in(epd));
+}
+
+/**
+ * usb_endpoint_is_int_out - check if the endpoint is interrupt OUT
+ * @epd: endpoint to be checked
+ *
+ * Returns true if the endpoint has interrupt transfer type and OUT direction,
+ * otherwise it returns false.
+ */
+
+static inline int usb_endpoint_is_int_out(const struct usb_endpoint_descriptor *epd)
+{
+       return (usb_endpoint_xfer_int(epd) && usb_endpoint_dir_out(epd));
+}
+
+#endif /* older kernel versions */

drivers/staging/frontier/surface_sysfs.h

···
+/* If you are going to abuse the preprocessor, why not ABUSE the preprocessor?
+   I stuck this header in a separate file so I don't have to look at it */
+
+// FIXME Need locking or atomic ops
+
+#define show_set_mbit(dname,value,bit)																			\
+static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)		\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+	int temp = (1 && (t->value & (1 << bit)));					\
+	return sprintf(buf, "%d\n", temp);			\
+}									\
+static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)	\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+	int temp = simple_strtoul(buf, NULL, 10);			\
+	if(temp > 0) { long b = 1 << bit; t->value |= b; } \
+	else { long b = ~(1 << bit); t->value &= b ;				 \
+	return count;							\
+}									\
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_##value, set_##value);
+
+#define show_set_ebit(dname,enumname,value,bit)																			\
+static ssize_t show_##bit(struct device *dev, struct device_attribute *attr, char *buf)		\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+  enum enumname l = bit; \
+  int temp = t->value & (1 << l);						\
+	return sprintf(buf, "%d\n", temp);			\
+}									\
+static ssize_t set_##bit(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)	\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+	int temp = simple_strtoul(buf, NULL, 10);			\
+  enum enumname l = bit;\
+	long b  = 1 << l; \
+	if(temp > 0) { t->value |= b; }	\
+	else { t->value &= ~b ;				\
+	return count;							\
+}									\
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_##value, set_##value);
+
+// FIXME FOR CORRECTLY SETTING HEX from a string
+#define show_set_mcmd(dname,value)																			\
+static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)		\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+  int count = 0;\
+	int i; \
+	for (i = 0,i<sizeof(dname); i++) count += snprintf(buf, "%02x",t->dname[i]); \
+  return(count);\
+}									\
+static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)	\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+	int temp = simple_strtoul(buf, NULL, 10);			\
+	t->value = temp;						\
+	return count;							\
+}									\
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_##value, set_##value);
+
+#define show_set_mint(dname,value)				\
+static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)		\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+	return sprintf(buf, "%d\n", t->value);			\
+}									\
+static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)	\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+	int temp = simple_strtoul(buf, NULL, 10);			\
+	t->value = temp;						\
+	return count;							\
+}									\
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_##value, set_##value);
+
+#define show_set_mchar(dname,value)																				\
+static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)		\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+	return sprintf(buf, "%c\n", t->value);			\
+}									\
+static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)	\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_##dname *t = usb_get_intfdata(intf);			\
+	int temp = simple_strtoul(buf, NULL, 10);			\
+	t->value = temp;						\
+	return count;							\
+}									\
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_##value, set_##value);

drivers/staging/frontier/tranzport.c

···
+/*
+ * Frontier Designs Tranzport driver
+ *
+ * Copyright (C) 2007 Michael Taht ([e-mail])
+ *
+ * Based on the usbled driver and ldusb drivers by
+ *
+ * Copyright (C) 2004 Greg Kroah-Hartman ([e-mail])
+ * Copyright (C) 2005 Michael Hund <[e-mail]>
+ *
+ * The ldusb driver was, in turn, derived from Lego USB Tower driver
+ * Copyright (C) 2003 David Glance <[e-mail]>
+ *		 2001-2004 Juergen Stuber <[e-mail]>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License as
+ *	published by the Free Software Foundation, version 2.
+ *
+ */
+
+/**
+ * This driver uses a ring buffer for time critical reading of
+ * interrupt in reports and provides read and write methods for
+ * raw interrupt reports.
+ */
+
+/* Note: this currently uses a dumb ringbuffer for reads and writes.
+ * A more optimal driver would cache and kill off outstanding urbs that are
+ * now invalid, and ignore ones that already were in the queue but valid
+ * as we only have 17 commands for the tranzport. In particular this is
+ * key for getting lights to flash in time as otherwise many commands
+ * can be buffered up before the light change makes it to the interface.
+*/
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/version.h>
+
+#include <asm/uaccess.h>
+#include <linux/input.h>
+#include <linux/usb.h>
+#include <linux/poll.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 19)
+#include frontier_compat.h
+#endif
+
+/* Define these values to match your devices */
+#define VENDOR_ID   0x165b
+#define PRODUCT_ID	0x8101
+
+#ifdef CONFIG_USB_DYNAMIC_MINORS
+#define USB_TRANZPORT_MINOR_BASE	0
+#else
+// FIXME 176 - is the ldusb driver's minor - apply for a minor soon
+#define USB_TRANZPORT_MINOR_BASE	177
+#endif
+
+/* table of devices that work with this driver */
+static struct usb_device_id usb_tranzport_table [] = {
+	{ USB_DEVICE(VENDOR_ID, PRODUCT_ID) },
+	{ }					/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, usb_tranzport_table);
+MODULE_VERSION("0.33");
+MODULE_AUTHOR("Mike Taht <[e-mail]>");
+MODULE_DESCRIPTION("Tranzport USB Driver");
+MODULE_LICENSE("GPL");
+MODULE_SUPPORTED_DEVICE("Frontier Designs Tranzport Control Surface");
+
+/* These two aren't done yet */
+
+#define SUPPRESS_EXTRA_ONLINE_EVENTS 0
+#define BUFFERED_WRITES 0
+
+#define SUPPRESS_EXTRA_OFFLINE_EVENTS 1
+#define COMPRESS_WHEEL_EVENTS 1
+#define BUFFERED_READS 1
+#define RING_BUFFER_SIZE 1000
+#define WRITE_BUFFER_SIZE 34
+#define TRANZPORT_USB_TIMEOUT 10
+
+
+static int debug = 0;
+
+/* Use our own dbg macro */
+#define dbg_info(dev, format, arg...) do { if (debug) dev_info(dev , format , ## arg); } while (0)
+
+/* Module parameters */
+
+module_param(debug, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug enabled or not");
+
+/* All interrupt in transfers are collected in a ring buffer to
+ * avoid racing conditions and get better performance of the driver.
+ */
+
+static int ring_buffer_size = RING_BUFFER_SIZE;
+
+module_param(ring_buffer_size, int,  S_IRUGO);
+MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");
+
+/* The write_buffer can one day contain more than one interrupt out transfer.
+ */
+static int write_buffer_size = WRITE_BUFFER_SIZE;
+module_param(write_buffer_size, int,  S_IRUGO);
+MODULE_PARM_DESC(write_buffer_size, "Write buffer size");
+
+/*
+ * Increase the interval for debugging purposes.
+ * or set to 1 to use the standard interval from the endpoint descriptors.
+ */
+
+static int min_interrupt_in_interval = TRANZPORT_USB_TIMEOUT;
+module_param(min_interrupt_in_interval, int, 0);
+MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");
+
+static int min_interrupt_out_interval = TRANZPORT_USB_TIMEOUT;
+module_param(min_interrupt_out_interval, int, 0);
+MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");
+
+struct tranzport_cmd {
+    unsigned char cmd[8];
+};
+
+enum LightID {
+	LightRecord = 0,
+	LightTrackrec,
+	LightTrackmute,
+	LightTracksolo,
+	LightAnysolo,
+	LightLoop,
+	LightPunch
+	};
+
+static const char *Lightname[8] = { "LightRecord",
+																		"LightTracrec",
+																		"LightTrackmute",
+																		"LightTrackSolo",
+																		"LightAnySolo",
+																		"LightLoop",
+																		"LightPunch",
+																		NULL };
+
+
+/* Structure to hold all of our device specific stuff */
+
+struct usb_tranzport {
+	struct semaphore	sem;		/* locks this structure */
+	struct usb_interface*	intf;		/* save off the usb interface pointer */
+
+	int			open_count;	/* number of times this port has been opened */
+
+	struct tranzport_cmd	(*ring_buffer)[RING_BUFFER_SIZE]; /* just make c happy */
+	unsigned int		ring_head;
+	unsigned int		ring_tail;
+
+	wait_queue_head_t	read_wait;
+	wait_queue_head_t	write_wait;
+
+	unsigned char*		interrupt_in_buffer;
+	struct usb_endpoint_descriptor* interrupt_in_endpoint;
+	struct urb*		interrupt_in_urb;
+	int			interrupt_in_interval;
+	size_t	interrupt_in_endpoint_size;
+	int			interrupt_in_running;
+	int			interrupt_in_done;
+
+	char*			interrupt_out_buffer;
+	struct usb_endpoint_descriptor* interrupt_out_endpoint;
+	struct urb*		interrupt_out_urb;
+	int			interrupt_out_interval;
+	size_t	interrupt_out_endpoint_size;
+	int			interrupt_out_busy;
+
+	/* Sysfs and translation support */
+
+	int event; /* alternate interface to events */
+	int wheel; /* - for negative, 0 for none, + for positive */
+	unsigned char dump_state; /* 0 if disabled 1 if enabled */
+	unsigned char enable; /* 0 if disabled 1 if enabled */
+	unsigned char offline; /* if the device is out of range or asleep */
+	unsigned char compress_wheel; /* flag to compress wheel events */
+	unsigned char light; /* 7 bits used */
+	unsigned char last_cmd[8];
+	unsigned char last_input[8];
+	unsigned char screen[40]; // We'll also have cells
+
+};
+
+/* prevent races between open() and disconnect() */
+static DEFINE_MUTEX(disconnect_mutex);
+
+static struct usb_driver usb_tranzport_driver;
+
+/**
+ *	usb_tranzport_abort_transfers
+ *      aborts transfers and frees associated data structures
+ */
+static void usb_tranzport_abort_transfers(struct usb_tranzport *dev)
+{
+	/* shutdown transfer */
+	if (dev->interrupt_in_running) {
+		dev->interrupt_in_running = 0;
+		if (dev->intf)
+			usb_kill_urb(dev->interrupt_in_urb);
+	}
+	if (dev->interrupt_out_busy)
+		if (dev->intf)
+			usb_kill_urb(dev->interrupt_out_urb);
+}
+
+// FIXME ~light not good enough or correct - need atomic set_bit
+
+#define show_set_light(value)	\
+static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)		\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_tranzport *t = usb_get_intfdata(intf);		\
+	enum LightID light = value;					\
+	int temp = (1 && (t->light & (1 << light)));			\
+	return sprintf(buf, "%d\n", temp );				\
+}									\
+static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)	\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_tranzport *t = usb_get_intfdata(intf);		\
+	int temp = simple_strtoul(buf, NULL, 10);			\
+	enum LightID light = (temp << value) & (t->light << value);	\
+	t->light = (t->light & ~light) ;				\
+	return count;							\
+}									\
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_##value, set_##value);
+
+show_set_light(LightRecord);
+show_set_light(LightTrackrec);
+show_set_light(LightTrackmute);
+show_set_light(LightTracksolo);
+show_set_light(LightAnysolo);
+show_set_light(LightLoop);
+show_set_light(LightPunch);
+
+
+#define show_set_int(value)	\
+static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)		\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_tranzport *t = usb_get_intfdata(intf);			\
+									\
+	return sprintf(buf, "%d\n", t->value);			\
+}									\
+static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)	\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_tranzport *t = usb_get_intfdata(intf);			\
+	int temp = simple_strtoul(buf, NULL, 10);			\
+									\
+	t->value = temp;						\
+	return count;							\
+}									\
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_##value, set_##value);
+
+show_set_int(enable);
+show_set_int(offline);
+show_set_int(compress_wheel);
+show_set_int(dump_state);
+show_set_int(wheel);
+show_set_int(event);
+
+#define show_set_cmd(value)	\
+static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)		\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_tranzport *t = usb_get_intfdata(intf);			\
+									\
+	return sprintf(buf, "%d\n", t->value);			\
+}									\
+static ssize_t set_##value(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)	\
+{									\
+	struct usb_interface *intf = to_usb_interface(dev);		\
+	struct usb_tranzport *t = usb_get_intfdata(intf);			\
+	int temp = simple_strtoul(buf, NULL, 10);			\
+									\
+	t->value = temp;						\
+	return count;							\
+}									\
+static DEVICE_ATTR(value, S_IWUGO | S_IRUGO, show_##value, set_##value);
+
+
+
+
+/**
+ *	usb_tranzport_delete
+ */
+static void usb_tranzport_delete(struct usb_tranzport *dev)
+{
+	usb_tranzport_abort_transfers(dev);
+	/*  This is just too twisted to be correct */
+	if(dev->intf != NULL) {
+	device_remove_file(&dev->intf->dev, &dev_attr_LightRecord);
+	device_remove_file(&dev->intf->dev, &dev_attr_LightTrackrec);
+	device_remove_file(&dev->intf->dev, &dev_attr_LightTrackmute);
+	device_remove_file(&dev->intf->dev, &dev_attr_LightTracksolo);
+	device_remove_file(&dev->intf->dev, &dev_attr_LightTrackmute);
+	device_remove_file(&dev->intf->dev, &dev_attr_LightAnysolo);
+	device_remove_file(&dev->intf->dev, &dev_attr_LightLoop);
+	device_remove_file(&dev->intf->dev, &dev_attr_LightPunch);
+	device_remove_file(&dev->intf->dev, &dev_attr_wheel);
+	device_remove_file(&dev->intf->dev, &dev_attr_enable);
+	device_remove_file(&dev->intf->dev, &dev_attr_event);
+	device_remove_file(&dev->intf->dev, &dev_attr_offline);
+	device_remove_file(&dev->intf->dev, &dev_attr_compress_wheel);
+
+	device_remove_file(&dev->intf->dev, &dev_attr_dump_state);
+	}
+
+	/* free data structures */
+	usb_free_urb(dev->interrupt_in_urb);
+	usb_free_urb(dev->interrupt_out_urb);
+	kfree(dev->ring_buffer);
+	kfree(dev->interrupt_in_buffer);
+	kfree(dev->interrupt_out_buffer);
+	kfree(dev);
+}
+
+/**
+ *	usb_tranzport_interrupt_in_callback
+ */
+
+static void usb_tranzport_interrupt_in_callback(struct urb *urb)
+{
+	struct usb_tranzport *dev = urb->context;
+	unsigned int next_ring_head;
+	int retval = -1;
+
+	if (urb->status) {
+		if (urb->status == -ENOENT ||
+		    urb->status == -ECONNRESET ||
+		    urb->status == -ESHUTDOWN) {
+			goto exit;
+		} else {
+			dbg_info(&dev->intf->dev, "%s: nonzero status received: %d\n",
+				 __FUNCTION__, urb->status);
+			goto resubmit; /* maybe we can recover */
+		}
+	}
+
+	if (urb->actual_length != 8) {
+		dev_warn(&dev->intf->dev,
+			 "Urb length was %d bytes!! Do something intelligent \n", urb->actual_length);
+	} else {
+		dbg_info(&dev->intf->dev, "%s: received: %02x%02x%02x%02x%02x%02x%02x%02x\n",
+			 __FUNCTION__, dev->interrupt_in_buffer[0],dev->interrupt_in_buffer[1],dev->interrupt_in_buffer[2],dev->interrupt_in_buffer[3],dev->interrupt_in_buffer[4],dev->interrupt_in_buffer[5],dev->interrupt_in_buffer[6],dev->interrupt_in_buffer[7]);
+#if SUPPRESS_EXTRA_OFFLINE_EVENTS
+		if(dev->offline == 2 && dev->interrupt_in_buffer[1] == 0xff) { goto resubmit; }
+		if(dev->offline == 1 && dev->interrupt_in_buffer[1] == 0xff) { dev->offline = 2; goto resubmit; }
+
+/* Always pass one offline event up the stack */
+		if(dev->offline > 0 && dev->interrupt_in_buffer[1] != 0xff) { dev->offline = 0; }
+		if(dev->offline == 0 && dev->interrupt_in_buffer[1] == 0xff) { dev->offline = 1; }
+
+#endif
+		dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n", __FUNCTION__,dev->ring_head,dev->ring_tail);
+
+		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
+
+		if (next_ring_head != dev->ring_tail) {
+			memcpy(&((*dev->ring_buffer)[dev->ring_head]), dev->interrupt_in_buffer, urb->actual_length);
+			dev->ring_head = next_ring_head;
+			retval = 0;
+			memset(dev->interrupt_in_buffer, 0, urb->actual_length);
+		} else {
+			dev_warn(&dev->intf->dev,
+				 "Ring buffer overflow, %d bytes dropped\n",
+				 urb->actual_length);
+			memset(dev->interrupt_in_buffer, 0, urb->actual_length);
+		}
+	}
+
+resubmit:
+	/* resubmit if we're still running */
+	if (dev->interrupt_in_running && dev->intf) {
+		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
+		if (retval)
+			dev_err(&dev->intf->dev,
+				"usb_submit_urb failed (%d)\n", retval);
+	}
+
+exit:
+	dev->interrupt_in_done = 1;
+	wake_up_interruptible(&dev->read_wait);
+}
+
+/**
+ *	usb_tranzport_interrupt_out_callback
+ */
+static void usb_tranzport_interrupt_out_callback(struct urb *urb)
+{
+	struct usb_tranzport *dev = urb->context;
+
+	/* sync/async unlink faults aren't errors */
+	if (urb->status && !(urb->status == -ENOENT ||
+			     urb->status == -ECONNRESET ||
+			     urb->status == -ESHUTDOWN))
+		dbg_info(&dev->intf->dev,
+			 "%s - nonzero write interrupt status received: %d\n",
+			 __FUNCTION__, urb->status);
+
+	dev->interrupt_out_busy = 0;
+	wake_up_interruptible(&dev->write_wait);
+}
+
+/**
+ *	usb_tranzport_open
+ */
+static int usb_tranzport_open(struct inode *inode, struct file *file)
+{
+	struct usb_tranzport *dev;
+	int subminor;
+	int retval = 0;
+	struct usb_interface *interface;
+
+	nonseekable_open(inode, file);
+	subminor = iminor(inode);
+
+	mutex_lock(&disconnect_mutex);
+
+	interface = usb_find_interface(&usb_tranzport_driver, subminor);
+
+	if (!interface) {
+		err("%s - error, can't find device for minor %d\n",
+		     __FUNCTION__, subminor);
+		retval = -ENODEV;
+		goto unlock_disconnect_exit;
+	}
+
+	dev = usb_get_intfdata(interface);
+
+	if (!dev) {
+		retval = -ENODEV;
+		goto unlock_disconnect_exit;
+	}
+
+	/* lock this device */
+	if (down_interruptible(&dev->sem)) {
+		retval = -ERESTARTSYS;
+		goto unlock_disconnect_exit;
+	}
+
+	/* allow opening only once */
+	if (dev->open_count) {
+		retval = -EBUSY;
+		goto unlock_exit;
+	}
+	dev->open_count = 1;
+
+	/* initialize in direction */
+	dev->ring_head = 0;
+	dev->ring_tail = 0;
+	usb_fill_int_urb(dev->interrupt_in_urb,
+			 interface_to_usbdev(interface),
+			 usb_rcvintpipe(interface_to_usbdev(interface),
+					dev->interrupt_in_endpoint->bEndpointAddress),
+			 dev->interrupt_in_buffer,
+			 dev->interrupt_in_endpoint_size,
+			 usb_tranzport_interrupt_in_callback,
+			 dev,
+			 dev->interrupt_in_interval);
+
+	dev->interrupt_in_running = 1;
+	dev->interrupt_in_done = 0;
+	dev->enable = 1;
+	dev->offline = 0;
+	dev->compress_wheel = 1;
+
+	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
+	if (retval) {
+		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
+		dev->interrupt_in_running = 0;
+		dev->open_count = 0;
+		goto unlock_exit;
+	}
+
+	/* save device in the file's private structure */
+	file->private_data = dev;
+
+
+unlock_exit:
+	up(&dev->sem);
+
+unlock_disconnect_exit:
+	mutex_unlock(&disconnect_mutex);
+
+	return retval;
+}
+
+/**
+ *	usb_tranzport_release
+ */
+static int usb_tranzport_release(struct inode *inode, struct file *file)
+{
+	struct usb_tranzport *dev;
+	int retval = 0;
+
+	dev = file->private_data;
+
+	if (dev == NULL) {
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	if (down_interruptible(&dev->sem)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	if (dev->open_count != 1) {
+		retval = -ENODEV;
+		goto unlock_exit;
+	}
+
+	if (dev->intf == NULL) {
+		/* the device was unplugged before the file was released */
+		up(&dev->sem);
+		/* unlock here as usb_tranzport_delete frees dev */
+		usb_tranzport_delete(dev);
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	/* wait until write transfer is finished */
+	if (dev->interrupt_out_busy)
+		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
+	usb_tranzport_abort_transfers(dev);
+	dev->open_count = 0;
+
+unlock_exit:
+	up(&dev->sem);
+
+exit:
+	return retval;
+}
+
+/**
+ *	usb_tranzport_poll
+ */
+static unsigned int usb_tranzport_poll(struct file *file, poll_table *wait)
+{
+	struct usb_tranzport *dev;
+	unsigned int mask = 0;
+
+	dev = file->private_data;
+
+	poll_wait(file, &dev->read_wait, wait);
+	poll_wait(file, &dev->write_wait, wait);
+
+	if (dev->ring_head != dev->ring_tail)
+		mask |= POLLIN | POLLRDNORM;
+	if (!dev->interrupt_out_busy)
+		mask |= POLLOUT | POLLWRNORM;
+
+	return mask;
+}
+
+/**
+ *	usb_tranzport_read
+ */
+static ssize_t usb_tranzport_read(struct file *file, char __user *buffer, size_t count,
+			   loff_t *ppos)
+{
+	struct usb_tranzport *dev;
+	size_t bytes_to_read;
+	int retval = 0;
+
+#if BUFFERED_READS
+	int c = 0;
+#endif
+
+#if COMPRESS_WHEEL_EVENTS
+	signed char oldwheel;
+	signed char newwheel;
+	int cancompress = 1;
+	int next_tail;
+#endif
+
+/* do I have such a thing as a null event? */
+
+	dev = file->private_data;
+
+	/* verify that we actually have some data to read */
+	if (count == 0)
+		goto exit;
+
+	/* lock this object */
+	if (down_interruptible(&dev->sem)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	/* verify that the device wasn't unplugged */
+	if (dev->intf == NULL) {
+		retval = -ENODEV;
+		err("No device or device unplugged %d\n", retval);
+		goto unlock_exit;
+	}
+
+	while (dev->ring_head == dev->ring_tail) {
+
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto unlock_exit;
+		}
+		// atomic_cmp_exchange(&dev->interrupt_in_done,0,0);
+		dev->interrupt_in_done = 0 ; /* tiny race - FIXME: make atomic? */
+		retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
+		if (retval < 0) {
+			goto unlock_exit;
+		}
+	}
+
+	dbg_info(&dev->intf->dev, "%s: copying to userspace: %02x%02x%02x%02x%02x%02x%02x%02x\n",
+			 __FUNCTION__, (*dev->ring_buffer)[dev->ring_tail].cmd[0],(*dev->ring_buffer)[dev->ring_tail].cmd[1],(*dev->ring_buffer)[dev->ring_tail].cmd[2],(*dev->ring_buffer)[dev->ring_tail].cmd[3],(*dev->ring_buffer)[dev->ring_tail].cmd[4],(*dev->ring_buffer)[dev->ring_tail].cmd[5],(*dev->ring_buffer)[dev->ring_tail].cmd[6],(*dev->ring_buffer)[dev->ring_tail].cmd[7]);
+
+#if BUFFERED_READS
+	   c = 0;
+	   while((c < count) && (dev->ring_tail != dev->ring_head)) {
+
+/* This started off in the lower level service routine, and I moved it here. Then my brain died. Not done yet. */
+#if COMPRESS_WHEEL_EVENTS
+		next_tail = (dev->ring_tail+1) % ring_buffer_size;
+		if(dev->compress_wheel) cancompress = 1;
+		while(dev->ring_head != next_tail && cancompress == 1 ) {
+			newwheel = (*dev->ring_buffer)[next_tail].cmd[6];
+			oldwheel = (*dev->ring_buffer)[dev->ring_tail].cmd[6];
+			// if both are wheel events, and no buttons have changes (FIXME, do I have to check?),
+			// and we are the same sign, we can compress +- 7F
+			// FIXME: saner check for overflow! - max of +- 7F
+			// FIXME the math is wrong for going in reverse, actually, as the midi spec doesn't allow signed chars
+
+	dbg_info(&dev->intf->dev, "%s: trying to compress: %02x%02x%02x%02x%02x %02x %02x %02x\n",
+			 __FUNCTION__, (*dev->ring_buffer)[dev->ring_tail].cmd[0],(*dev->ring_buffer)[dev->ring_tail].cmd[1],(*dev->ring_buffer)[dev->ring_tail].cmd[2],(*dev->ring_buffer)[dev->ring_tail].cmd[3],(*dev->ring_buffer)[dev->ring_tail].cmd[4],(*dev->ring_buffer)[dev->ring_tail].cmd[5],(*dev->ring_buffer)[dev->ring_tail].cmd[6],(*dev->ring_buffer)[dev->ring_tail].cmd[7]);
+
+
+			if(((*dev->ring_buffer)[dev->ring_tail].cmd[6] != 0 &&
+			    (*dev->ring_buffer)[next_tail].cmd[6] != 0 ) &&
+				((newwheel > 0 && oldwheel > 0) ||
+				(newwheel < 0 && oldwheel < 0)) &&
+				((*dev->ring_buffer)[dev->ring_tail].cmd[2] == (*dev->ring_buffer)[next_tail].cmd[2]) &&
+				((*dev->ring_buffer)[dev->ring_tail].cmd[3] == (*dev->ring_buffer)[next_tail].cmd[3]) &&
+				((*dev->ring_buffer)[dev->ring_tail].cmd[4] == (*dev->ring_buffer)[next_tail].cmd[4]) &&
+				((*dev->ring_buffer)[dev->ring_tail].cmd[5] == (*dev->ring_buffer)[next_tail].cmd[5]))
+ {
+	dbg_info(&dev->intf->dev, "%s: should compress: %02x%02x%02x%02x%02x%02x%02x%02x\n",
+			 __FUNCTION__, (*dev->ring_buffer)[dev->ring_tail].cmd[0],(*dev->ring_buffer)[dev->ring_tail].cmd[1],(*dev->ring_buffer)[dev->ring_tail].cmd[2],(*dev->ring_buffer)[dev->ring_tail].cmd[3],(*dev->ring_buffer)[dev->ring_tail].cmd[4],(*dev->ring_buffer)[dev->ring_tail].cmd[5],(*dev->ring_buffer)[dev->ring_tail].cmd[6],(*dev->ring_buffer)[dev->ring_tail].cmd[7]);
+
+				newwheel += oldwheel;
+				if(oldwheel > 0 && !(newwheel > 0)) {
+					newwheel = 0x7f;
+					cancompress = 0;
+				}
+				if(oldwheel < 0 && !(newwheel < 0)) {
+					newwheel = 0x80;
+					cancompress = 0;
+				}
+
+				(*dev->ring_buffer)[next_tail].cmd[6] = newwheel;
+				dev->ring_tail = next_tail;
+				next_tail = (dev->ring_tail+1) % ring_buffer_size;
+			} else {
+				cancompress = 0;
+			}
+		}
+#endif /* COMPRESS_WHEEL_EVENTS */
+
+		if (copy_to_user(&buffer[c], &(*dev->ring_buffer)[dev->ring_tail], 8)) {
+			retval = -EFAULT;
+			goto unlock_exit;
+		}
+
+		dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
+		c+=8;
+		dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n", __FUNCTION__,dev->ring_head,dev->ring_tail);
+	   }
+	   retval = c;
+
+#else
+	if (copy_to_user(buffer, &(*dev->ring_buffer)[dev->ring_tail], 8)) {
+		retval = -EFAULT;
+		goto unlock_exit;
+	}
+
+	dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
+	dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n", __FUNCTION__,dev->ring_head,dev->ring_tail);
+
+	retval = 8;
+#endif /* BUFFERED_READS */
+
+unlock_exit:
+	/* unlock the device */
+	up(&dev->sem);
+
+exit:
+	return retval;
+}
+
+/**
+ *	usb_tranzport_write
+ */
+static ssize_t usb_tranzport_write(struct file *file, const char __user *buffer,
+			    size_t count, loff_t *ppos)
+{
+	struct usb_tranzport *dev;
+	size_t bytes_to_write;
+	int retval = 0;
+
+	dev = file->private_data;
+
+	/* verify that we actually have some data to write */
+	if (count == 0)
+		goto exit;
+
+	/* lock this object */
+	if (down_interruptible(&dev->sem)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	/* verify that the device wasn't unplugged */
+	if (dev->intf == NULL) {
+		retval = -ENODEV;
+		err("No device or device unplugged %d\n", retval);
+		goto unlock_exit;
+	}
+
+	/* wait until previous transfer is finished */
+	if (dev->interrupt_out_busy) {
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto unlock_exit;
+		}
+		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
+		if (retval < 0) {
+			goto unlock_exit;
+		}
+	}
+
+	/* write the data into interrupt_out_buffer from userspace */
+	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
+	if (bytes_to_write < count)
+		dev_warn(&dev->intf->dev, "Write buffer overflow, %zd bytes dropped\n",count-bytes_to_write);
+
+	dbg_info(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n", __FUNCTION__, count, bytes_to_write);
+
+	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
+		retval = -EFAULT;
+		goto unlock_exit;
+	}
+
+	if (dev->interrupt_out_endpoint == NULL) {
+		err("Endpoint should not be be null! \n");
+		goto unlock_exit;
+	}
+
+	/* send off the urb */
+	usb_fill_int_urb(dev->interrupt_out_urb,
+			 interface_to_usbdev(dev->intf),
+			 usb_sndintpipe(interface_to_usbdev(dev->intf),
+					dev->interrupt_out_endpoint->bEndpointAddress),
+			 dev->interrupt_out_buffer,
+			 bytes_to_write,
+			 usb_tranzport_interrupt_out_callback,
+			 dev,
+			 dev->interrupt_out_interval);
+
+	dev->interrupt_out_busy = 1;
+	wmb();
+
+	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
+	if (retval) {
+		dev->interrupt_out_busy = 0;
+		err("Couldn't submit interrupt_out_urb %d\n", retval);
+		goto unlock_exit;
+	}
+	retval = bytes_to_write;
+
+unlock_exit:
+	/* unlock the device */
+	up(&dev->sem);
+
+exit:
+	return retval;
+}
+
+/* file operations needed when we register this driver */
+static const struct file_operations usb_tranzport_fops = {
+	.owner =	THIS_MODULE,
+	.read  =	usb_tranzport_read,
+	.write =	usb_tranzport_write,
+	.open =		usb_tranzport_open,
+	.release =	usb_tranzport_release,
+	.poll =		usb_tranzport_poll,
+};
+
+/*
+ * usb class driver info in order to get a minor number from the usb core,
+ * and to have the device registered with the driver core
+ */
+static struct usb_class_driver usb_tranzport_class = {
+	.name =		"tranzport%d",
+	.fops =		&usb_tranzport_fops,
+	.minor_base =	USB_TRANZPORT_MINOR_BASE,
+};
+
+
+/**
+ *	usb_tranzport_probe
+ *
+ *	Called by the usb core when a new device is connected that it thinks
+ *	this driver might be interested in.
+ */
+static int usb_tranzport_probe(struct usb_interface *intf, const struct usb_device_id *id)
+{
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct usb_tranzport *dev = NULL;
+	struct usb_host_interface *iface_desc;
+	struct usb_endpoint_descriptor *endpoint;
+	int i;
+	int true_size;
+	int retval = -ENOMEM;
+
+	/* allocate memory for our device state and intialize it */
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (dev == NULL) {
+		dev_err(&intf->dev, "Out of memory\n");
+		goto exit;
+	}
+	init_MUTEX(&dev->sem);
+	dev->intf = intf;
+	init_waitqueue_head(&dev->read_wait);
+	init_waitqueue_head(&dev->write_wait);
+
+	iface_desc = intf->cur_altsetting;
+
+	/* set up the endpoint information */
+	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
+		endpoint = &iface_desc->endpoint[i].desc;
+
+		if (usb_endpoint_is_int_in(endpoint))
+			dev->interrupt_in_endpoint = endpoint;
+
+		if (usb_endpoint_is_int_out(endpoint))
+			dev->interrupt_out_endpoint = endpoint;
+	}
+	if (dev->interrupt_in_endpoint == NULL) {
+		dev_err(&intf->dev, "Interrupt in endpoint not found\n");
+		goto error;
+	}
+	if (dev->interrupt_out_endpoint == NULL)
+		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");
+
+
+	dev->interrupt_in_endpoint_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
+
+	if (dev->interrupt_in_endpoint_size != 8)
+	    dev_warn(&intf->dev, "Interrupt in endpoint size is not 8!\n");
+
+	if(ring_buffer_size == 0) { ring_buffer_size = RING_BUFFER_SIZE; }
+	true_size = min(ring_buffer_size,RING_BUFFER_SIZE);
+	/* FIXME - there are more usb_alloc routines for dma correctness. Needed? */
+
+	dev->ring_buffer = kmalloc((true_size*sizeof(struct tranzport_cmd))+8, GFP_KERNEL);
+
+	if (!dev->ring_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate ring_buffer of size %d\n",true_size);
+		goto error;
+	}
+	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
+	if (!dev->interrupt_in_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
+		goto error;
+	}
+	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->interrupt_in_urb) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
+		goto error;
+	}
+	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize) :
+									 udev->descriptor.bMaxPacketSize0;
+
+	if (dev->interrupt_out_endpoint_size !=8)
+		dev_warn(&intf->dev, "Interrupt out endpoint size is not 8!)\n");
+
+	dev->interrupt_out_buffer = kmalloc(write_buffer_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
+	if (!dev->interrupt_out_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_out_buffer\n");
+		goto error;
+	}
+	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->interrupt_out_urb) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
+		goto error;
+	}
+	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
+	if (dev->interrupt_out_endpoint)
+		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
+
+	/* we can register the device now, as it is ready */
+	usb_set_intfdata(intf, dev);
+
+	retval = usb_register_dev(intf, &usb_tranzport_class);
+	if (retval) {
+		/* something prevented us from registering this driver */
+		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
+		usb_set_intfdata(intf, NULL);
+		goto error;
+	}
+
+	if((retval = device_create_file(&intf->dev, &dev_attr_LightRecord))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_LightTrackrec))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_LightTrackmute))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_LightTracksolo))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_LightAnysolo))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_LightLoop))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_LightPunch))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_wheel))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_event))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_dump_state))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_compress_wheel))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_enable))) goto error;
+	if((retval = device_create_file(&intf->dev, &dev_attr_offline))) goto error;
+
+	/* let the user know what node this device is now attached to */
+	dev_info(&intf->dev, "Tranzport Device #%d now attached to major %d minor %d\n",
+		(intf->minor - USB_TRANZPORT_MINOR_BASE), USB_MAJOR, intf->minor);
+
+exit:
+	return retval;
+
+error:
+	usb_tranzport_delete(dev);
+
+	return retval;
+}
+
+/**
+ *	usb_tranzport_disconnect
+ *
+ *	Called by the usb core when the device is removed from the system.
+ */
+static void usb_tranzport_disconnect(struct usb_interface *intf)
+{
+	struct usb_tranzport *dev;
+	int minor;
+	mutex_lock(&disconnect_mutex);
+	dev = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, NULL);
+	down(&dev->sem);
+	minor = intf->minor;
+	/* give back our minor */
+	usb_deregister_dev(intf, &usb_tranzport_class);
+
+	/* if the device is not opened, then we clean up right now */
+	if (!dev->open_count) {
+		up(&dev->sem);
+		usb_tranzport_delete(dev);
+	} else {
+		dev->intf = NULL;
+		up(&dev->sem);
+	}
+
+	mutex_unlock(&disconnect_mutex);
+
+	dev_info(&intf->dev, "Tranzport Surface #%d now disconnected\n",
+		 (minor - USB_TRANZPORT_MINOR_BASE));
+}
+
+/* usb specific object needed to register this driver with the usb subsystem */
+static struct usb_driver usb_tranzport_driver = {
+	.name =		"tranzport",
+	.probe =	usb_tranzport_probe,
+	.disconnect =	usb_tranzport_disconnect,
+	.id_table =	usb_tranzport_table,
+};
+
+/**
+ *	usb_tranzport_init
+ */
+static int __init usb_tranzport_init(void)
+{
+	int retval;
+
+	/* register this driver with the USB subsystem */
+	retval = usb_register(&usb_tranzport_driver);
+	if (retval)
+		err("usb_register failed for the "__FILE__" driver. Error number %d\n", retval);
+
+	return retval;
+}
+
+/**
+ *	usb_tranzport_exit
+ */
+static void __exit usb_tranzport_exit(void)
+{
+	/* deregister this driver with the USB subsystem */
+	usb_deregister(&usb_tranzport_driver);
+}
+
+module_init(usb_tranzport_init);
+module_exit(usb_tranzport_exit);
+