[deliverable/linux.git] / drivers / usb / usb-skeleton.c

/*
 * USB Skeleton driver - 2.2
 *
 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
 *
 *	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 is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
 * but has been rewritten to be easier to read and use.
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kref.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/mutex.h>


/* Define these values to match your devices */
#define USB_SKEL_VENDOR_ID	0xfff0
#define USB_SKEL_PRODUCT_ID	0xfff0

/* table of devices that work with this driver */
static const struct usb_device_id skel_table[] = {
	{ USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
	{ }					/* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, skel_table);


/* Get a minor range for your devices from the usb maintainer */
#define USB_SKEL_MINOR_BASE	192

/* our private defines. if this grows any larger, use your own .h file */
#define MAX_TRANSFER		(PAGE_SIZE - 512)
/* MAX_TRANSFER is chosen so that the VM is not stressed by
   allocations > PAGE_SIZE and the number of packets in a page
   is an integer 512 is the largest possible packet on EHCI */
#define WRITES_IN_FLIGHT	8
/* arbitrarily chosen */

/* Structure to hold all of our device specific stuff */
struct usb_skel {
	struct usb_device	*udev;			/* the usb device for this device */
	struct usb_interface	*interface;		/* the interface for this device */
	struct semaphore	limit_sem;		/* limiting the number of writes in progress */
	struct usb_anchor	submitted;		/* in case we need to retract our submissions */
	struct urb		*bulk_in_urb;		/* the urb to read data with */
	unsigned char           *bulk_in_buffer;	/* the buffer to receive data */
	size_t			bulk_in_size;		/* the size of the receive buffer */
	size_t			bulk_in_filled;		/* number of bytes in the buffer */
	size_t			bulk_in_copied;		/* already copied to user space */
	__u8			bulk_in_endpointAddr;	/* the address of the bulk in endpoint */
	__u8			bulk_out_endpointAddr;	/* the address of the bulk out endpoint */
	int			errors;			/* the last request tanked */
	bool			ongoing_read;		/* a read is going on */
	bool			processed_urb;		/* indicates we haven't processed the urb */
	spinlock_t		err_lock;		/* lock for errors */
	struct kref		kref;
	struct mutex		io_mutex;		/* synchronize I/O with disconnect */
	struct completion	bulk_in_completion;	/* to wait for an ongoing read */
};
#define to_skel_dev(d) container_of(d, struct usb_skel, kref)

static struct usb_driver skel_driver;
static void skel_draw_down(struct usb_skel *dev);

static void skel_delete(struct kref *kref)
{
	struct usb_skel *dev = to_skel_dev(kref);

	usb_free_urb(dev->bulk_in_urb);
	usb_put_dev(dev->udev);
	kfree(dev->bulk_in_buffer);
	kfree(dev);
}

static int skel_open(struct inode *inode, struct file *file)
{
	struct usb_skel *dev;
	struct usb_interface *interface;
	int subminor;
	int retval = 0;

	subminor = iminor(inode);

	interface = usb_find_interface(&skel_driver, subminor);
	if (!interface) {
		err("%s - error, can't find device for minor %d",
		     __func__, subminor);
		retval = -ENODEV;
		goto exit;
	}

	dev = usb_get_intfdata(interface);
	if (!dev) {
		retval = -ENODEV;
		goto exit;
	}

	/* increment our usage count for the device */
	kref_get(&dev->kref);

	/* lock the device to allow correctly handling errors
	 * in resumption */
	mutex_lock(&dev->io_mutex);

	retval = usb_autopm_get_interface(interface);
	if (retval)
		goto out_err;

	/* save our object in the file's private structure */
	file->private_data = dev;
	mutex_unlock(&dev->io_mutex);

exit:
	return retval;
}

static int skel_release(struct inode *inode, struct file *file)
{
	struct usb_skel *dev;

	dev = file->private_data;
	if (dev == NULL)
		return -ENODEV;

	/* allow the device to be autosuspended */
	mutex_lock(&dev->io_mutex);
	if (dev->interface)
		usb_autopm_put_interface(dev->interface);
	mutex_unlock(&dev->io_mutex);

	/* decrement the count on our device */
	kref_put(&dev->kref, skel_delete);
	return 0;
}

static int skel_flush(struct file *file, fl_owner_t id)
{
	struct usb_skel *dev;
	int res;

	dev = file->private_data;
	if (dev == NULL)
		return -ENODEV;

	/* wait for io to stop */
	mutex_lock(&dev->io_mutex);
	skel_draw_down(dev);

	/* read out errors, leave subsequent opens a clean slate */
	spin_lock_irq(&dev->err_lock);
	res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
	dev->errors = 0;
	spin_unlock_irq(&dev->err_lock);

	mutex_unlock(&dev->io_mutex);

	return res;
}

static void skel_read_bulk_callback(struct urb *urb)
{
	struct usb_skel *dev;

	dev = urb->context;

	spin_lock(&dev->err_lock);
	/* sync/async unlink faults aren't errors */
	if (urb->status) {
		if (!(urb->status == -ENOENT ||
		    urb->status == -ECONNRESET ||
		    urb->status == -ESHUTDOWN))
			err("%s - nonzero write bulk status received: %d",
			    __func__, urb->status);

		dev->errors = urb->status;
	} else {
		dev->bulk_in_filled = urb->actual_length;
	}
	dev->ongoing_read = 0;
	spin_unlock(&dev->err_lock);

	complete(&dev->bulk_in_completion);
}

static int skel_do_read_io(struct usb_skel *dev, size_t count)
{
	int rv;

	/* prepare a read */
	usb_fill_bulk_urb(dev->bulk_in_urb,
			dev->udev,
			usb_rcvbulkpipe(dev->udev,
				dev->bulk_in_endpointAddr),
			dev->bulk_in_buffer,
			min(dev->bulk_in_size, count),
			skel_read_bulk_callback,
			dev);
	/* tell everybody to leave the URB alone */
	spin_lock_irq(&dev->err_lock);
	dev->ongoing_read = 1;
	spin_unlock_irq(&dev->err_lock);

	/* do it */
	rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
	if (rv < 0) {
		err("%s - failed submitting read urb, error %d",
			__func__, rv);
		dev->bulk_in_filled = 0;
		rv = (rv == -ENOMEM) ? rv : -EIO;
		spin_lock_irq(&dev->err_lock);
		dev->ongoing_read = 0;
		spin_unlock_irq(&dev->err_lock);
	}

	return rv;
}

static ssize_t skel_read(struct file *file, char *buffer, size_t count,
			 loff_t *ppos)
{
	struct usb_skel *dev;
	int rv;
	bool ongoing_io;

	dev = file->private_data;

	/* if we cannot read at all, return EOF */
	if (!dev->bulk_in_urb || !count)
		return 0;

	/* no concurrent readers */
	rv = mutex_lock_interruptible(&dev->io_mutex);
	if (rv < 0)
		return rv;

	if (!dev->interface) {		/* disconnect() was called */
		rv = -ENODEV;
		goto exit;
	}

	/* if IO is under way, we must not touch things */
retry:
	spin_lock_irq(&dev->err_lock);
	ongoing_io = dev->ongoing_read;
	spin_unlock_irq(&dev->err_lock);

	if (ongoing_io) {
		/* nonblocking IO shall not wait */
		if (file->f_flags & O_NONBLOCK) {
			rv = -EAGAIN;
			goto exit;
		}
		/*
		 * IO may take forever
		 * hence wait in an interruptible state
		 */
		rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
		if (rv < 0)
			goto exit;
		/*
		 * by waiting we also semiprocessed the urb
		 * we must finish now
		 */
		dev->bulk_in_copied = 0;
		dev->processed_urb = 1;
	}

	if (!dev->processed_urb) {
		/*
		 * the URB hasn't been processed
		 * do it now
		 */
		wait_for_completion(&dev->bulk_in_completion);
		dev->bulk_in_copied = 0;
		dev->processed_urb = 1;
	}

	/* errors must be reported */
	rv = dev->errors;
	if (rv < 0) {
		/* any error is reported once */
		dev->errors = 0;
		/* to preserve notifications about reset */
		rv = (rv == -EPIPE) ? rv : -EIO;
		/* no data to deliver */
		dev->bulk_in_filled = 0;
		/* report it */
		goto exit;
	}

	/*
	 * if the buffer is filled we may satisfy the read
	 * else we need to start IO
	 */

	if (dev->bulk_in_filled) {
		/* we had read data */
		size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
		size_t chunk = min(available, count);

		if (!available) {
			/*
			 * all data has been used
			 * actual IO needs to be done
			 */
			rv = skel_do_read_io(dev, count);
			if (rv < 0)
				goto exit;
			else
				goto retry;
		}
		/*
		 * data is available
		 * chunk tells us how much shall be copied
		 */

		if (copy_to_user(buffer,
				 dev->bulk_in_buffer + dev->bulk_in_copied,
				 chunk))
			rv = -EFAULT;
		else
			rv = chunk;

		dev->bulk_in_copied += chunk;

		/*
		 * if we are asked for more than we have,
		 * we start IO but don't wait
		 */
		if (available < count)
			skel_do_read_io(dev, count - chunk);
	} else {
		/* no data in the buffer */
		rv = skel_do_read_io(dev, count);
		if (rv < 0)
			goto exit;
		else if (!(file->f_flags & O_NONBLOCK))
			goto retry;
		rv = -EAGAIN;
	}
exit:
	mutex_unlock(&dev->io_mutex);
	return rv;
}

static void skel_write_bulk_callback(struct urb *urb)
{
	struct usb_skel *dev;

	dev = urb->context;

	/* sync/async unlink faults aren't errors */
	if (urb->status) {
		if (!(urb->status == -ENOENT ||
		    urb->status == -ECONNRESET ||
		    urb->status == -ESHUTDOWN))
			err("%s - nonzero write bulk status received: %d",
			    __func__, urb->status);

		spin_lock(&dev->err_lock);
		dev->errors = urb->status;
		spin_unlock(&dev->err_lock);
	}

	/* free up our allocated buffer */
	usb_free_coherent(urb->dev, urb->transfer_buffer_length,
			  urb->transfer_buffer, urb->transfer_dma);
	up(&dev->limit_sem);
}

static ssize_t skel_write(struct file *file, const char *user_buffer,
			  size_t count, loff_t *ppos)
{
	struct usb_skel *dev;
	int retval = 0;
	struct urb *urb = NULL;
	char *buf = NULL;
	size_t writesize = min(count, (size_t)MAX_TRANSFER);

	dev = file->private_data;

	/* verify that we actually have some data to write */
	if (count == 0)
		goto exit;

	/*
	 * limit the number of URBs in flight to stop a user from using up all
	 * RAM
	 */
	if (!(file->f_flags & O_NONBLOCK)) {
		if (down_interruptible(&dev->limit_sem)) {
			retval = -ERESTARTSYS;
			goto exit;
		}
	} else {
		if (down_trylock(&dev->limit_sem)) {
			retval = -EAGAIN;
			goto exit;
		}
	}

	spin_lock_irq(&dev->err_lock);
	retval = dev->errors;
	if (retval < 0) {
		/* any error is reported once */
		dev->errors = 0;
		/* to preserve notifications about reset */
		retval = (retval == -EPIPE) ? retval : -EIO;
	}
	spin_unlock_irq(&dev->err_lock);
	if (retval < 0)
		goto error;

	/* create a urb, and a buffer for it, and copy the data to the urb */
	urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!urb) {
		retval = -ENOMEM;
		goto error;
	}

	buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
				 &urb->transfer_dma);
	if (!buf) {
		retval = -ENOMEM;
		goto error;
	}

	if (copy_from_user(buf, user_buffer, writesize)) {
		retval = -EFAULT;
		goto error;
	}

	/* this lock makes sure we don't submit URBs to gone devices */
	mutex_lock(&dev->io_mutex);
	if (!dev->interface) {		/* disconnect() was called */
		mutex_unlock(&dev->io_mutex);
		retval = -ENODEV;
		goto error;
	}

	/* initialize the urb properly */
	usb_fill_bulk_urb(urb, dev->udev,
			  usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
			  buf, writesize, skel_write_bulk_callback, dev);
	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
	usb_anchor_urb(urb, &dev->submitted);

	/* send the data out the bulk port */
	retval = usb_submit_urb(urb, GFP_KERNEL);
	mutex_unlock(&dev->io_mutex);
	if (retval) {
		err("%s - failed submitting write urb, error %d", __func__,
		    retval);
		goto error_unanchor;
	}

	/*
	 * release our reference to this urb, the USB core will eventually free
	 * it entirely
	 */
	usb_free_urb(urb);


	return writesize;

error_unanchor:
	usb_unanchor_urb(urb);
error:
	if (urb) {
		usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
		usb_free_urb(urb);
	}
	up(&dev->limit_sem);

exit:
	return retval;
}

static const struct file_operations skel_fops = {
	.owner =	THIS_MODULE,
	.read =		skel_read,
	.write =	skel_write,
	.open =		skel_open,
	.release =	skel_release,
	.flush =	skel_flush,
	.llseek =	noop_llseek,
};

/*
 * 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 skel_class = {
	.name =		"skel%d",
	.fops =		&skel_fops,
	.minor_base =	USB_SKEL_MINOR_BASE,
};

static int skel_probe(struct usb_interface *interface,
		      const struct usb_device_id *id)
{
	struct usb_skel *dev;
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	size_t buffer_size;
	int i;
	int retval = -ENOMEM;

	/* allocate memory for our device state and initialize it */
	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev) {
		err("Out of memory");
		goto error;
	}
	kref_init(&dev->kref);
	sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
	mutex_init(&dev->io_mutex);
	spin_lock_init(&dev->err_lock);
	init_usb_anchor(&dev->submitted);
	init_completion(&dev->bulk_in_completion);

	dev->udev = usb_get_dev(interface_to_usbdev(interface));
	dev->interface = interface;

	/* set up the endpoint information */
	/* use only the first bulk-in and bulk-out endpoints */
	iface_desc = interface->cur_altsetting;
	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
		endpoint = &iface_desc->endpoint[i].desc;

		if (!dev->bulk_in_endpointAddr &&
		    usb_endpoint_is_bulk_in(endpoint)) {
			/* we found a bulk in endpoint */
			buffer_size = usb_endpoint_maxp(endpoint);
			dev->bulk_in_size = buffer_size;
			dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
			dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
			if (!dev->bulk_in_buffer) {
				err("Could not allocate bulk_in_buffer");
				goto error;
			}
			dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
			if (!dev->bulk_in_urb) {
				err("Could not allocate bulk_in_urb");
				goto error;
			}
		}

		if (!dev->bulk_out_endpointAddr &&
		    usb_endpoint_is_bulk_out(endpoint)) {
			/* we found a bulk out endpoint */
			dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
		}
	}
	if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
		err("Could not find both bulk-in and bulk-out endpoints");
		goto error;
	}

	/* save our data pointer in this interface device */
	usb_set_intfdata(interface, dev);

	/* we can register the device now, as it is ready */
	retval = usb_register_dev(interface, &skel_class);
	if (retval) {
		/* something prevented us from registering this driver */
		err("Not able to get a minor for this device.");
		usb_set_intfdata(interface, NULL);
		goto error;
	}

	/* let the user know what node this device is now attached to */
	dev_info(&interface->dev,
		 "USB Skeleton device now attached to USBSkel-%d",
		 interface->minor);
	return 0;

error:
	if (dev)
		/* this frees allocated memory */
		kref_put(&dev->kref, skel_delete);
	return retval;
}

static void skel_disconnect(struct usb_interface *interface)
{
	struct usb_skel *dev;
	int minor = interface->minor;

	dev = usb_get_intfdata(interface);
	usb_set_intfdata(interface, NULL);

	/* give back our minor */
	usb_deregister_dev(interface, &skel_class);

	/* prevent more I/O from starting */
	mutex_lock(&dev->io_mutex);
	dev->interface = NULL;
	mutex_unlock(&dev->io_mutex);

	usb_kill_anchored_urbs(&dev->submitted);

	/* decrement our usage count */
	kref_put(&dev->kref, skel_delete);

	dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
}

static void skel_draw_down(struct usb_skel *dev)
{
	int time;

	time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
	if (!time)
		usb_kill_anchored_urbs(&dev->submitted);
	usb_kill_urb(dev->bulk_in_urb);
}

static int skel_suspend(struct usb_interface *intf, pm_message_t message)
{
	struct usb_skel *dev = usb_get_intfdata(intf);

	if (!dev)
		return 0;
	skel_draw_down(dev);
	return 0;
}

static int skel_resume(struct usb_interface *intf)
{
	return 0;
}

static int skel_pre_reset(struct usb_interface *intf)
{
	struct usb_skel *dev = usb_get_intfdata(intf);

	mutex_lock(&dev->io_mutex);
	skel_draw_down(dev);

	return 0;
}

static int skel_post_reset(struct usb_interface *intf)
{
	struct usb_skel *dev = usb_get_intfdata(intf);

	/* we are sure no URBs are active - no locking needed */
	dev->errors = -EPIPE;
	mutex_unlock(&dev->io_mutex);

	return 0;
}

static struct usb_driver skel_driver = {
	.name =		"skeleton",
	.probe =	skel_probe,
	.disconnect =	skel_disconnect,
	.suspend =	skel_suspend,
	.resume =	skel_resume,
	.pre_reset =	skel_pre_reset,
	.post_reset =	skel_post_reset,
	.id_table =	skel_table,
	.supports_autosuspend = 1,
};

module_usb_driver(skel_driver);

MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4	1	/*
c0704541	2	* USB Skeleton driver - 2.2
1da177e4 LT	3	*
	4	* Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License as
	8	* published by the Free Software Foundation, version 2.
	9	*
c0704541	10	* This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
121e287c	11	* but has been rewritten to be easier to read and use.
1da177e4 LT	12	*
	13	*/
	14
1da177e4 LT	15	#include <linux/kernel.h>
	16	#include <linux/errno.h>
	17	#include <linux/init.h>
	18	#include <linux/slab.h>
	19	#include <linux/module.h>
	20	#include <linux/kref.h>
3ae9da1c	21	#include <linux/uaccess.h>
1da177e4	22	#include <linux/usb.h>
121e287c	23	#include <linux/mutex.h>
1da177e4 LT	24
	25
	26	/* Define these values to match your devices */
	27	#define USB_SKEL_VENDOR_ID 0xfff0
	28	#define USB_SKEL_PRODUCT_ID 0xfff0
	29
	30	/* table of devices that work with this driver */
1bd4f29d	31	static const struct usb_device_id skel_table[] = {
1da177e4 LT	32	{ USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
	33	{ } /* Terminating entry */
	34	};
c0704541	35	MODULE_DEVICE_TABLE(usb, skel_table);
1da177e4 LT	36
	37
	38	/* Get a minor range for your devices from the usb maintainer */
	39	#define USB_SKEL_MINOR_BASE 192
	40
ff906518	41	/* our private defines. if this grows any larger, use your own .h file */
c0704541	42	#define MAX_TRANSFER (PAGE_SIZE - 512)
ba35e02b ON	43	/* MAX_TRANSFER is chosen so that the VM is not stressed by
	44	allocations > PAGE_SIZE and the number of packets in a page
	45	is an integer 512 is the largest possible packet on EHCI */
ff906518	46	#define WRITES_IN_FLIGHT 8
ba35e02b	47	/* arbitrarily chosen */
ff906518	48
1da177e4 LT	49	/* Structure to hold all of our device specific stuff */
1da177e4 LT	50	struct usb_skel {
ba35e02b ON	51	struct usb_device udev; / the usb device for this device */
ba35e02b ON	52	struct usb_interface interface; / the interface for this device */
ff906518	53	struct semaphore limit_sem; /* limiting the number of writes in progress */
403dfb58	54	struct usb_anchor submitted; /* in case we need to retract our submissions */
e7389cc9	55	struct urb bulk_in_urb; / the urb to read data with */
c0704541	56	unsigned char bulk_in_buffer; / the buffer to receive data */
1da177e4	57	size_t bulk_in_size; /* the size of the receive buffer */
e7389cc9 ON	58	size_t bulk_in_filled; /* number of bytes in the buffer */
e7389cc9 ON	59	size_t bulk_in_copied; /* already copied to user space */
1da177e4 LT	60	__u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
1da177e4 LT	61	__u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
403dfb58	62	int errors; /* the last request tanked */
e7389cc9 ON	63	bool ongoing_read; /* a read is going on */
e7389cc9 ON	64	bool processed_urb; /* indicates we haven't processed the urb */
403dfb58	65	spinlock_t err_lock; /* lock for errors */
1da177e4	66	struct kref kref;
121e287c	67	struct mutex io_mutex; /* synchronize I/O with disconnect */
e7389cc9	68	struct completion bulk_in_completion; /* to wait for an ongoing read */
1da177e4 LT	69	};
	70	#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
	71
	72	static struct usb_driver skel_driver;
403dfb58	73	static void skel_draw_down(struct usb_skel *dev);
1da177e4 LT	74
1da177e4 LT	75	static void skel_delete(struct kref *kref)
c0704541	76	{
1da177e4 LT	77	struct usb_skel *dev = to_skel_dev(kref);
1da177e4 LT	78
e7389cc9	79	usb_free_urb(dev->bulk_in_urb);
1da177e4	80	usb_put_dev(dev->udev);
c0704541 LFC	81	kfree(dev->bulk_in_buffer);
c0704541 LFC	82	kfree(dev);
1da177e4 LT	83	}
	84
	85	static int skel_open(struct inode inode, struct file file)
	86	{
	87	struct usb_skel *dev;
	88	struct usb_interface *interface;
	89	int subminor;
	90	int retval = 0;
	91
	92	subminor = iminor(inode);
	93
	94	interface = usb_find_interface(&skel_driver, subminor);
	95	if (!interface) {
3ae9da1c	96	err("%s - error, can't find device for minor %d",
441b62c1	97	__func__, subminor);
1da177e4 LT	98	retval = -ENODEV;
	99	goto exit;
	100	}
	101
	102	dev = usb_get_intfdata(interface);
	103	if (!dev) {
	104	retval = -ENODEV;
	105	goto exit;
	106	}
	107
5b064708 ON	108	/* increment our usage count for the device */
	109	kref_get(&dev->kref);
	110
758f7e16 ON	111	/* lock the device to allow correctly handling errors
	112	* in resumption */
	113	mutex_lock(&dev->io_mutex);
	114
e28dbb06 ML	115	retval = usb_autopm_get_interface(interface);
	116	if (retval)
	117	goto out_err;
1da177e4 LT	118
	119	/* save our object in the file's private structure */
	120	file->private_data = dev;
f7294055	121	mutex_unlock(&dev->io_mutex);
1da177e4 LT	122
	123	exit:
	124	return retval;
	125	}
	126
	127	static int skel_release(struct inode inode, struct file file)
	128	{
	129	struct usb_skel *dev;
	130
e53e841d	131	dev = file->private_data;
1da177e4 LT	132	if (dev == NULL)
	133	return -ENODEV;
	134
01d883d4 AS	135	/* allow the device to be autosuspended */
01d883d4 AS	136	mutex_lock(&dev->io_mutex);
e28dbb06	137	if (dev->interface)
01d883d4 AS	138	usb_autopm_put_interface(dev->interface);
	139	mutex_unlock(&dev->io_mutex);
	140
1da177e4 LT	141	/* decrement the count on our device */
	142	kref_put(&dev->kref, skel_delete);
	143	return 0;
	144	}
	145
403dfb58 ON	146	static int skel_flush(struct file *file, fl_owner_t id)
	147	{
	148	struct usb_skel *dev;
	149	int res;
	150
e53e841d	151	dev = file->private_data;
403dfb58 ON	152	if (dev == NULL)
	153	return -ENODEV;
	154
	155	/* wait for io to stop */
	156	mutex_lock(&dev->io_mutex);
	157	skel_draw_down(dev);
	158
	159	/* read out errors, leave subsequent opens a clean slate */
	160	spin_lock_irq(&dev->err_lock);
	161	res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
	162	dev->errors = 0;
	163	spin_unlock_irq(&dev->err_lock);
	164
	165	mutex_unlock(&dev->io_mutex);
	166
	167	return res;
	168	}
	169
e7389cc9 ON	170	static void skel_read_bulk_callback(struct urb *urb)
	171	{
	172	struct usb_skel *dev;
	173
	174	dev = urb->context;
	175
	176	spin_lock(&dev->err_lock);
	177	/* sync/async unlink faults aren't errors */
	178	if (urb->status) {
3ae9da1c	179	if (!(urb->status == -ENOENT \|\|
e7389cc9 ON	180	urb->status == -ECONNRESET \|\|
	181	urb->status == -ESHUTDOWN))
	182	err("%s - nonzero write bulk status received: %d",
	183	__func__, urb->status);
	184
	185	dev->errors = urb->status;
	186	} else {
	187	dev->bulk_in_filled = urb->actual_length;
	188	}
	189	dev->ongoing_read = 0;
	190	spin_unlock(&dev->err_lock);
	191
	192	complete(&dev->bulk_in_completion);
	193	}
	194
	195	static int skel_do_read_io(struct usb_skel *dev, size_t count)
	196	{
	197	int rv;
	198
	199	/* prepare a read */
	200	usb_fill_bulk_urb(dev->bulk_in_urb,
	201	dev->udev,
	202	usb_rcvbulkpipe(dev->udev,
	203	dev->bulk_in_endpointAddr),
	204	dev->bulk_in_buffer,
	205	min(dev->bulk_in_size, count),
	206	skel_read_bulk_callback,
	207	dev);
	208	/* tell everybody to leave the URB alone */
	209	spin_lock_irq(&dev->err_lock);
	210	dev->ongoing_read = 1;
	211	spin_unlock_irq(&dev->err_lock);
	212
	213	/* do it */
	214	rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
	215	if (rv < 0) {
	216	err("%s - failed submitting read urb, error %d",
	217	__func__, rv);
	218	dev->bulk_in_filled = 0;
	219	rv = (rv == -ENOMEM) ? rv : -EIO;
	220	spin_lock_irq(&dev->err_lock);
	221	dev->ongoing_read = 0;
	222	spin_unlock_irq(&dev->err_lock);
	223	}
	224
	225	return rv;
	226	}
	227
3ae9da1c GKH	228	static ssize_t skel_read(struct file file, char buffer, size_t count,
3ae9da1c GKH	229	loff_t *ppos)
1da177e4 LT	230	{
1da177e4 LT	231	struct usb_skel *dev;
e7389cc9 ON	232	int rv;
e7389cc9 ON	233	bool ongoing_io;
1da177e4	234
e53e841d	235	dev = file->private_data;
121e287c	236
e7389cc9 ON	237	/* if we cannot read at all, return EOF */
	238	if (!dev->bulk_in_urb \|\| !count)
	239	return 0;
	240
	241	/* no concurrent readers */
	242	rv = mutex_lock_interruptible(&dev->io_mutex);
	243	if (rv < 0)
	244	return rv;
	245
121e287c	246	if (!dev->interface) { /* disconnect() was called */
e7389cc9	247	rv = -ENODEV;
121e287c AS	248	goto exit;
	249	}
	250
e7389cc9 ON	251	/* if IO is under way, we must not touch things */
	252	retry:
	253	spin_lock_irq(&dev->err_lock);
	254	ongoing_io = dev->ongoing_read;
	255	spin_unlock_irq(&dev->err_lock);
	256
	257	if (ongoing_io) {
8cd01664 ON	258	/* nonblocking IO shall not wait */
	259	if (file->f_flags & O_NONBLOCK) {
	260	rv = -EAGAIN;
	261	goto exit;
	262	}
e7389cc9 ON	263	/*
	264	* IO may take forever
	265	* hence wait in an interruptible state
	266	*/
	267	rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
	268	if (rv < 0)
	269	goto exit;
	270	/*
	271	* by waiting we also semiprocessed the urb
	272	* we must finish now
	273	*/
	274	dev->bulk_in_copied = 0;
	275	dev->processed_urb = 1;
	276	}
	277
	278	if (!dev->processed_urb) {
	279	/*
	280	* the URB hasn't been processed
	281	* do it now
	282	*/
	283	wait_for_completion(&dev->bulk_in_completion);
	284	dev->bulk_in_copied = 0;
	285	dev->processed_urb = 1;
1da177e4 LT	286	}
1da177e4 LT	287
e7389cc9	288	/* errors must be reported */
3ae9da1c GKH	289	rv = dev->errors;
3ae9da1c GKH	290	if (rv < 0) {
e7389cc9 ON	291	/* any error is reported once */
	292	dev->errors = 0;
	293	/* to preserve notifications about reset */
	294	rv = (rv == -EPIPE) ? rv : -EIO;
	295	/* no data to deliver */
	296	dev->bulk_in_filled = 0;
	297	/* report it */
	298	goto exit;
	299	}
	300
	301	/*
	302	* if the buffer is filled we may satisfy the read
	303	* else we need to start IO
	304	*/
	305
	306	if (dev->bulk_in_filled) {
	307	/* we had read data */
	308	size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
	309	size_t chunk = min(available, count);
	310
	311	if (!available) {
	312	/*
	313	* all data has been used
	314	* actual IO needs to be done
	315	*/
	316	rv = skel_do_read_io(dev, count);
	317	if (rv < 0)
	318	goto exit;
	319	else
	320	goto retry;
	321	}
	322	/*
	323	* data is available
	324	* chunk tells us how much shall be copied
	325	*/
	326
	327	if (copy_to_user(buffer,
	328	dev->bulk_in_buffer + dev->bulk_in_copied,
	329	chunk))
	330	rv = -EFAULT;
	331	else
	332	rv = chunk;
	333
	334	dev->bulk_in_copied += chunk;
	335
	336	/*
	337	* if we are asked for more than we have,
	338	* we start IO but don't wait
	339	*/
	340	if (available < count)
	341	skel_do_read_io(dev, count - chunk);
	342	} else {
	343	/* no data in the buffer */
	344	rv = skel_do_read_io(dev, count);
	345	if (rv < 0)
	346	goto exit;
4de84057	347	else if (!(file->f_flags & O_NONBLOCK))
e7389cc9	348	goto retry;
8cd01664	349	rv = -EAGAIN;
e7389cc9	350	}
121e287c AS	351	exit:
121e287c AS	352	mutex_unlock(&dev->io_mutex);
e7389cc9	353	return rv;
1da177e4 LT	354	}
1da177e4 LT	355
7d12e780	356	static void skel_write_bulk_callback(struct urb *urb)
1da177e4 LT	357	{
	358	struct usb_skel *dev;
	359
cdc97792	360	dev = urb->context;
1da177e4 LT	361
1da177e4 LT	362	/* sync/async unlink faults aren't errors */
403dfb58	363	if (urb->status) {
3ae9da1c	364	if (!(urb->status == -ENOENT \|\|
403dfb58 ON	365	urb->status == -ECONNRESET \|\|
	366	urb->status == -ESHUTDOWN))
	367	err("%s - nonzero write bulk status received: %d",
441b62c1	368	__func__, urb->status);
403dfb58 ON	369
	370	spin_lock(&dev->err_lock);
	371	dev->errors = urb->status;
	372	spin_unlock(&dev->err_lock);
1da177e4 LT	373	}
	374
	375	/* free up our allocated buffer */
997ea58e DM	376	usb_free_coherent(urb->dev, urb->transfer_buffer_length,
997ea58e DM	377	urb->transfer_buffer, urb->transfer_dma);
ff906518	378	up(&dev->limit_sem);
1da177e4 LT	379	}
1da177e4 LT	380
3ae9da1c GKH	381	static ssize_t skel_write(struct file file, const char user_buffer,
3ae9da1c GKH	382	size_t count, loff_t *ppos)
1da177e4 LT	383	{
	384	struct usb_skel *dev;
	385	int retval = 0;
	386	struct urb *urb = NULL;
	387	char *buf = NULL;
c8dd7709	388	size_t writesize = min(count, (size_t)MAX_TRANSFER);
1da177e4	389
e53e841d	390	dev = file->private_data;
1da177e4 LT	391
	392	/* verify that we actually have some data to write */
	393	if (count == 0)
	394	goto exit;
	395
3ae9da1c GKH	396	/*
	397	* limit the number of URBs in flight to stop a user from using up all
	398	* RAM
	399	*/
4de84057	400	if (!(file->f_flags & O_NONBLOCK)) {
79819986 ON	401	if (down_interruptible(&dev->limit_sem)) {
	402	retval = -ERESTARTSYS;
	403	goto exit;
	404	}
	405	} else {
	406	if (down_trylock(&dev->limit_sem)) {
	407	retval = -EAGAIN;
	408	goto exit;
	409	}
c8dd7709	410	}
ff906518	411
403dfb58	412	spin_lock_irq(&dev->err_lock);
3ae9da1c GKH	413	retval = dev->errors;
3ae9da1c GKH	414	if (retval < 0) {
403dfb58 ON	415	/* any error is reported once */
	416	dev->errors = 0;
	417	/* to preserve notifications about reset */
	418	retval = (retval == -EPIPE) ? retval : -EIO;
	419	}
	420	spin_unlock_irq(&dev->err_lock);
	421	if (retval < 0)
	422	goto error;
	423
1da177e4 LT	424	/* create a urb, and a buffer for it, and copy the data to the urb */
	425	urb = usb_alloc_urb(0, GFP_KERNEL);
	426	if (!urb) {
	427	retval = -ENOMEM;
	428	goto error;
	429	}
	430
997ea58e DM	431	buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
997ea58e DM	432	&urb->transfer_dma);
1da177e4 LT	433	if (!buf) {
	434	retval = -ENOMEM;
	435	goto error;
	436	}
	437
ff906518	438	if (copy_from_user(buf, user_buffer, writesize)) {
1da177e4 LT	439	retval = -EFAULT;
	440	goto error;
	441	}
	442
ba35e02b ON	443	/* this lock makes sure we don't submit URBs to gone devices */
	444	mutex_lock(&dev->io_mutex);
	445	if (!dev->interface) { /* disconnect() was called */
	446	mutex_unlock(&dev->io_mutex);
	447	retval = -ENODEV;
	448	goto error;
	449	}
	450
1da177e4 LT	451	/* initialize the urb properly */
	452	usb_fill_bulk_urb(urb, dev->udev,
	453	usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
ff906518	454	buf, writesize, skel_write_bulk_callback, dev);
1da177e4	455	urb->transfer_flags \|= URB_NO_TRANSFER_DMA_MAP;
403dfb58	456	usb_anchor_urb(urb, &dev->submitted);
1da177e4 LT	457
	458	/* send the data out the bulk port */
	459	retval = usb_submit_urb(urb, GFP_KERNEL);
ba35e02b	460	mutex_unlock(&dev->io_mutex);
1da177e4	461	if (retval) {
3ae9da1c GKH	462	err("%s - failed submitting write urb, error %d", __func__,
3ae9da1c GKH	463	retval);
403dfb58	464	goto error_unanchor;
1da177e4 LT	465	}
1da177e4 LT	466
3ae9da1c GKH	467	/*
	468	* release our reference to this urb, the USB core will eventually free
	469	* it entirely
	470	*/
1da177e4 LT	471	usb_free_urb(urb);
1da177e4 LT	472
ba35e02b	473
ff906518	474	return writesize;
1da177e4	475
403dfb58 ON	476	error_unanchor:
403dfb58 ON	477	usb_unanchor_urb(urb);
1da177e4	478	error:
121e287c	479	if (urb) {
997ea58e	480	usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
121e287c AS	481	usb_free_urb(urb);
121e287c AS	482	}
ff906518	483	up(&dev->limit_sem);
121e287c AS	484
121e287c AS	485	exit:
1da177e4 LT	486	return retval;
	487	}
	488
066202dd	489	static const struct file_operations skel_fops = {
1da177e4 LT	490	.owner = THIS_MODULE,
	491	.read = skel_read,
	492	.write = skel_write,
	493	.open = skel_open,
	494	.release = skel_release,
403dfb58	495	.flush = skel_flush,
6038f373	496	.llseek = noop_llseek,
1da177e4 LT	497	};
1da177e4 LT	498
c0704541	499	/*
1da177e4	500	* usb class driver info in order to get a minor number from the usb core,
595b14cb	501	* and to have the device registered with the driver core
1da177e4 LT	502	*/
1da177e4 LT	503	static struct usb_class_driver skel_class = {
d6e5bcf4	504	.name = "skel%d",
1da177e4	505	.fops = &skel_fops,
1da177e4 LT	506	.minor_base = USB_SKEL_MINOR_BASE,
	507	};
	508
3ae9da1c GKH	509	static int skel_probe(struct usb_interface *interface,
3ae9da1c GKH	510	const struct usb_device_id *id)
1da177e4	511	{
c0704541	512	struct usb_skel *dev;
1da177e4 LT	513	struct usb_host_interface *iface_desc;
	514	struct usb_endpoint_descriptor *endpoint;
	515	size_t buffer_size;
	516	int i;
	517	int retval = -ENOMEM;
	518
	519	/* allocate memory for our device state and initialize it */
ff906518	520	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
c0704541	521	if (!dev) {
1da177e4 LT	522	err("Out of memory");
	523	goto error;
	524	}
1da177e4	525	kref_init(&dev->kref);
ff906518	526	sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
121e287c	527	mutex_init(&dev->io_mutex);
403dfb58 ON	528	spin_lock_init(&dev->err_lock);
403dfb58 ON	529	init_usb_anchor(&dev->submitted);
e7389cc9	530	init_completion(&dev->bulk_in_completion);
1da177e4 LT	531
	532	dev->udev = usb_get_dev(interface_to_usbdev(interface));
	533	dev->interface = interface;
	534
	535	/* set up the endpoint information */
	536	/* use only the first bulk-in and bulk-out endpoints */
	537	iface_desc = interface->cur_altsetting;
	538	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
	539	endpoint = &iface_desc->endpoint[i].desc;
	540
	541	if (!dev->bulk_in_endpointAddr &&
c0704541	542	usb_endpoint_is_bulk_in(endpoint)) {
1da177e4	543	/* we found a bulk in endpoint */
29cc8897	544	buffer_size = usb_endpoint_maxp(endpoint);
1da177e4 LT	545	dev->bulk_in_size = buffer_size;
	546	dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
	547	dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
	548	if (!dev->bulk_in_buffer) {
	549	err("Could not allocate bulk_in_buffer");
	550	goto error;
	551	}
e7389cc9 ON	552	dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
	553	if (!dev->bulk_in_urb) {
	554	err("Could not allocate bulk_in_urb");
	555	goto error;
	556	}
1da177e4 LT	557	}
	558
	559	if (!dev->bulk_out_endpointAddr &&
c0704541	560	usb_endpoint_is_bulk_out(endpoint)) {
1da177e4 LT	561	/* we found a bulk out endpoint */
	562	dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
	563	}
	564	}
	565	if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
	566	err("Could not find both bulk-in and bulk-out endpoints");
	567	goto error;
	568	}
	569
	570	/* save our data pointer in this interface device */
	571	usb_set_intfdata(interface, dev);
	572
	573	/* we can register the device now, as it is ready */
	574	retval = usb_register_dev(interface, &skel_class);
	575	if (retval) {
	576	/* something prevented us from registering this driver */
	577	err("Not able to get a minor for this device.");
	578	usb_set_intfdata(interface, NULL);
	579	goto error;
	580	}
	581
	582	/* let the user know what node this device is now attached to */
a5f5ea23 MK	583	dev_info(&interface->dev,
	584	"USB Skeleton device now attached to USBSkel-%d",
	585	interface->minor);
1da177e4 LT	586	return 0;
	587
	588	error:
	589	if (dev)
ba35e02b	590	/* this frees allocated memory */
1da177e4 LT	591	kref_put(&dev->kref, skel_delete);
	592	return retval;
	593	}
	594
	595	static void skel_disconnect(struct usb_interface *interface)
	596	{
	597	struct usb_skel *dev;
	598	int minor = interface->minor;
	599
1da177e4	600	dev = usb_get_intfdata(interface);
52a74999	601	usb_set_intfdata(interface, NULL);
1da177e4 LT	602
	603	/* give back our minor */
	604	usb_deregister_dev(interface, &skel_class);
	605
121e287c AS	606	/* prevent more I/O from starting */
	607	mutex_lock(&dev->io_mutex);
	608	dev->interface = NULL;
	609	mutex_unlock(&dev->io_mutex);
	610
e73c7247 ON	611	usb_kill_anchored_urbs(&dev->submitted);
e73c7247 ON	612
1da177e4 LT	613	/* decrement our usage count */
	614	kref_put(&dev->kref, skel_delete);
	615
a5f5ea23	616	dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
1da177e4 LT	617	}
1da177e4 LT	618
403dfb58 ON	619	static void skel_draw_down(struct usb_skel *dev)
	620	{
	621	int time;
	622
	623	time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
	624	if (!time)
	625	usb_kill_anchored_urbs(&dev->submitted);
e7389cc9	626	usb_kill_urb(dev->bulk_in_urb);
403dfb58 ON	627	}
403dfb58 ON	628
758f7e16 ON	629	static int skel_suspend(struct usb_interface *intf, pm_message_t message)
	630	{
	631	struct usb_skel *dev = usb_get_intfdata(intf);
	632
	633	if (!dev)
	634	return 0;
	635	skel_draw_down(dev);
	636	return 0;
	637	}
	638
3ae9da1c	639	static int skel_resume(struct usb_interface *intf)
758f7e16 ON	640	{
	641	return 0;
	642	}
	643
87d093e2 ON	644	static int skel_pre_reset(struct usb_interface *intf)
	645	{
	646	struct usb_skel *dev = usb_get_intfdata(intf);
	647
	648	mutex_lock(&dev->io_mutex);
	649	skel_draw_down(dev);
	650
	651	return 0;
	652	}
	653
	654	static int skel_post_reset(struct usb_interface *intf)
	655	{
	656	struct usb_skel *dev = usb_get_intfdata(intf);
	657
	658	/* we are sure no URBs are active - no locking needed */
	659	dev->errors = -EPIPE;
	660	mutex_unlock(&dev->io_mutex);
	661
	662	return 0;
	663	}
	664
1da177e4	665	static struct usb_driver skel_driver = {
1da177e4 LT	666	.name = "skeleton",
	667	.probe = skel_probe,
	668	.disconnect = skel_disconnect,
758f7e16 ON	669	.suspend = skel_suspend,
758f7e16 ON	670	.resume = skel_resume,
87d093e2 ON	671	.pre_reset = skel_pre_reset,
87d093e2 ON	672	.post_reset = skel_post_reset,
1da177e4	673	.id_table = skel_table,
ba35e02b	674	.supports_autosuspend = 1,
1da177e4 LT	675	};
1da177e4 LT	676
65db4305	677	module_usb_driver(skel_driver);
1da177e4 LT	678
1da177e4 LT	679	MODULE_LICENSE("GPL");