[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) {
		pr_err("%s - error, can't find device for minor %d\n",
			__func__, subminor);
		retval = -ENODEV;
		goto exit;
	}

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

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

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

	/* save our object in the file's private structure */
	file->private_data = dev;

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))
			dev_err(&dev->interface->dev,
				"%s - nonzero write bulk status received: %d\n",
				__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) {
		dev_err(&dev->interface->dev,
			"%s - failed submitting read urb, error %d\n",
			__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))
			dev_err(&dev->interface->dev,
				"%s - nonzero write bulk status received: %d\n",
				__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) {
		dev_err(&dev->interface->dev,
			"%s - failed submitting write urb, error %d\n",
			__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) {
		dev_err(&interface->dev, "Out of memory\n");
		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) {
				dev_err(&interface->dev,
					"Could not allocate bulk_in_buffer\n");
				goto error;
			}
			dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
			if (!dev->bulk_in_urb) {
				dev_err(&interface->dev,
					"Could not allocate bulk_in_urb\n");
				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)) {
		dev_err(&interface->dev,
			"Could not find both bulk-in and bulk-out endpoints\n");
		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 */
		dev_err(&interface->dev,
			"Not able to get a minor for this device.\n");
		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) {
4212cd74 GKH	96	pr_err("%s - error, can't find device for minor %d\n",
4212cd74 GKH	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
e28dbb06 ML	108	retval = usb_autopm_get_interface(interface);
e28dbb06 ML	109	if (retval)
e8cebb9c CS	110	goto exit;
	111
	112	/* increment our usage count for the device */
	113	kref_get(&dev->kref);
1da177e4 LT	114
	115	/* save our object in the file's private structure */
	116	file->private_data = dev;
	117
	118	exit:
	119	return retval;
	120	}
	121
	122	static int skel_release(struct inode inode, struct file file)
	123	{
	124	struct usb_skel *dev;
	125
e53e841d	126	dev = file->private_data;
1da177e4 LT	127	if (dev == NULL)
	128	return -ENODEV;
	129
01d883d4 AS	130	/* allow the device to be autosuspended */
01d883d4 AS	131	mutex_lock(&dev->io_mutex);
e28dbb06	132	if (dev->interface)
01d883d4 AS	133	usb_autopm_put_interface(dev->interface);
	134	mutex_unlock(&dev->io_mutex);
	135
1da177e4 LT	136	/* decrement the count on our device */
	137	kref_put(&dev->kref, skel_delete);
	138	return 0;
	139	}
	140
403dfb58 ON	141	static int skel_flush(struct file *file, fl_owner_t id)
	142	{
	143	struct usb_skel *dev;
	144	int res;
	145
e53e841d	146	dev = file->private_data;
403dfb58 ON	147	if (dev == NULL)
	148	return -ENODEV;
	149
	150	/* wait for io to stop */
	151	mutex_lock(&dev->io_mutex);
	152	skel_draw_down(dev);
	153
	154	/* read out errors, leave subsequent opens a clean slate */
	155	spin_lock_irq(&dev->err_lock);
	156	res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
	157	dev->errors = 0;
	158	spin_unlock_irq(&dev->err_lock);
	159
	160	mutex_unlock(&dev->io_mutex);
	161
	162	return res;
	163	}
	164
e7389cc9 ON	165	static void skel_read_bulk_callback(struct urb *urb)
	166	{
	167	struct usb_skel *dev;
	168
	169	dev = urb->context;
	170
	171	spin_lock(&dev->err_lock);
	172	/* sync/async unlink faults aren't errors */
	173	if (urb->status) {
3ae9da1c	174	if (!(urb->status == -ENOENT \|\|
e7389cc9 ON	175	urb->status == -ECONNRESET \|\|
e7389cc9 ON	176	urb->status == -ESHUTDOWN))
4212cd74 GKH	177	dev_err(&dev->interface->dev,
	178	"%s - nonzero write bulk status received: %d\n",
	179	__func__, urb->status);
e7389cc9 ON	180
	181	dev->errors = urb->status;
	182	} else {
	183	dev->bulk_in_filled = urb->actual_length;
	184	}
	185	dev->ongoing_read = 0;
	186	spin_unlock(&dev->err_lock);
	187
	188	complete(&dev->bulk_in_completion);
	189	}
	190
	191	static int skel_do_read_io(struct usb_skel *dev, size_t count)
	192	{
	193	int rv;
	194
	195	/* prepare a read */
	196	usb_fill_bulk_urb(dev->bulk_in_urb,
	197	dev->udev,
	198	usb_rcvbulkpipe(dev->udev,
	199	dev->bulk_in_endpointAddr),
	200	dev->bulk_in_buffer,
	201	min(dev->bulk_in_size, count),
	202	skel_read_bulk_callback,
	203	dev);
	204	/* tell everybody to leave the URB alone */
	205	spin_lock_irq(&dev->err_lock);
	206	dev->ongoing_read = 1;
	207	spin_unlock_irq(&dev->err_lock);
	208
	209	/* do it */
	210	rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
	211	if (rv < 0) {
4212cd74 GKH	212	dev_err(&dev->interface->dev,
4212cd74 GKH	213	"%s - failed submitting read urb, error %d\n",
e7389cc9 ON	214	__func__, rv);
	215	dev->bulk_in_filled = 0;
	216	rv = (rv == -ENOMEM) ? rv : -EIO;
	217	spin_lock_irq(&dev->err_lock);
	218	dev->ongoing_read = 0;
	219	spin_unlock_irq(&dev->err_lock);
	220	}
	221
	222	return rv;
	223	}
	224
3ae9da1c GKH	225	static ssize_t skel_read(struct file file, char buffer, size_t count,
3ae9da1c GKH	226	loff_t *ppos)
1da177e4 LT	227	{
1da177e4 LT	228	struct usb_skel *dev;
e7389cc9 ON	229	int rv;
e7389cc9 ON	230	bool ongoing_io;
1da177e4	231
e53e841d	232	dev = file->private_data;
121e287c	233
e7389cc9 ON	234	/* if we cannot read at all, return EOF */
	235	if (!dev->bulk_in_urb \|\| !count)
	236	return 0;
	237
	238	/* no concurrent readers */
	239	rv = mutex_lock_interruptible(&dev->io_mutex);
	240	if (rv < 0)
	241	return rv;
	242
121e287c	243	if (!dev->interface) { /* disconnect() was called */
e7389cc9	244	rv = -ENODEV;
121e287c AS	245	goto exit;
	246	}
	247
e7389cc9 ON	248	/* if IO is under way, we must not touch things */
	249	retry:
	250	spin_lock_irq(&dev->err_lock);
	251	ongoing_io = dev->ongoing_read;
	252	spin_unlock_irq(&dev->err_lock);
	253
	254	if (ongoing_io) {
8cd01664 ON	255	/* nonblocking IO shall not wait */
	256	if (file->f_flags & O_NONBLOCK) {
	257	rv = -EAGAIN;
	258	goto exit;
	259	}
e7389cc9 ON	260	/*
	261	* IO may take forever
	262	* hence wait in an interruptible state
	263	*/
	264	rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
	265	if (rv < 0)
	266	goto exit;
	267	/*
	268	* by waiting we also semiprocessed the urb
	269	* we must finish now
	270	*/
	271	dev->bulk_in_copied = 0;
	272	dev->processed_urb = 1;
	273	}
	274
	275	if (!dev->processed_urb) {
	276	/*
	277	* the URB hasn't been processed
	278	* do it now
	279	*/
	280	wait_for_completion(&dev->bulk_in_completion);
	281	dev->bulk_in_copied = 0;
	282	dev->processed_urb = 1;
1da177e4 LT	283	}
1da177e4 LT	284
e7389cc9	285	/* errors must be reported */
3ae9da1c GKH	286	rv = dev->errors;
3ae9da1c GKH	287	if (rv < 0) {
e7389cc9 ON	288	/* any error is reported once */
	289	dev->errors = 0;
	290	/* to preserve notifications about reset */
	291	rv = (rv == -EPIPE) ? rv : -EIO;
	292	/* no data to deliver */
	293	dev->bulk_in_filled = 0;
	294	/* report it */
	295	goto exit;
	296	}
	297
	298	/*
	299	* if the buffer is filled we may satisfy the read
	300	* else we need to start IO
	301	*/
	302
	303	if (dev->bulk_in_filled) {
	304	/* we had read data */
	305	size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
	306	size_t chunk = min(available, count);
	307
	308	if (!available) {
	309	/*
	310	* all data has been used
	311	* actual IO needs to be done
	312	*/
	313	rv = skel_do_read_io(dev, count);
	314	if (rv < 0)
	315	goto exit;
	316	else
	317	goto retry;
	318	}
	319	/*
	320	* data is available
	321	* chunk tells us how much shall be copied
	322	*/
	323
	324	if (copy_to_user(buffer,
	325	dev->bulk_in_buffer + dev->bulk_in_copied,
	326	chunk))
	327	rv = -EFAULT;
	328	else
	329	rv = chunk;
	330
	331	dev->bulk_in_copied += chunk;
	332
	333	/*
	334	* if we are asked for more than we have,
	335	* we start IO but don't wait
	336	*/
	337	if (available < count)
	338	skel_do_read_io(dev, count - chunk);
	339	} else {
	340	/* no data in the buffer */
	341	rv = skel_do_read_io(dev, count);
	342	if (rv < 0)
	343	goto exit;
4de84057	344	else if (!(file->f_flags & O_NONBLOCK))
e7389cc9	345	goto retry;
8cd01664	346	rv = -EAGAIN;
e7389cc9	347	}
121e287c AS	348	exit:
121e287c AS	349	mutex_unlock(&dev->io_mutex);
e7389cc9	350	return rv;
1da177e4 LT	351	}
1da177e4 LT	352
7d12e780	353	static void skel_write_bulk_callback(struct urb *urb)
1da177e4 LT	354	{
	355	struct usb_skel *dev;
	356
cdc97792	357	dev = urb->context;
1da177e4 LT	358
1da177e4 LT	359	/* sync/async unlink faults aren't errors */
403dfb58	360	if (urb->status) {
3ae9da1c	361	if (!(urb->status == -ENOENT \|\|
403dfb58 ON	362	urb->status == -ECONNRESET \|\|
403dfb58 ON	363	urb->status == -ESHUTDOWN))
4212cd74 GKH	364	dev_err(&dev->interface->dev,
	365	"%s - nonzero write bulk status received: %d\n",
	366	__func__, urb->status);
403dfb58 ON	367
	368	spin_lock(&dev->err_lock);
	369	dev->errors = urb->status;
	370	spin_unlock(&dev->err_lock);
1da177e4 LT	371	}
	372
	373	/* free up our allocated buffer */
997ea58e DM	374	usb_free_coherent(urb->dev, urb->transfer_buffer_length,
997ea58e DM	375	urb->transfer_buffer, urb->transfer_dma);
ff906518	376	up(&dev->limit_sem);
1da177e4 LT	377	}
1da177e4 LT	378
3ae9da1c GKH	379	static ssize_t skel_write(struct file file, const char user_buffer,
3ae9da1c GKH	380	size_t count, loff_t *ppos)
1da177e4 LT	381	{
	382	struct usb_skel *dev;
	383	int retval = 0;
	384	struct urb *urb = NULL;
	385	char *buf = NULL;
c8dd7709	386	size_t writesize = min(count, (size_t)MAX_TRANSFER);
1da177e4	387
e53e841d	388	dev = file->private_data;
1da177e4 LT	389
	390	/* verify that we actually have some data to write */
	391	if (count == 0)
	392	goto exit;
	393
3ae9da1c GKH	394	/*
	395	* limit the number of URBs in flight to stop a user from using up all
	396	* RAM
	397	*/
4de84057	398	if (!(file->f_flags & O_NONBLOCK)) {
79819986 ON	399	if (down_interruptible(&dev->limit_sem)) {
	400	retval = -ERESTARTSYS;
	401	goto exit;
	402	}
	403	} else {
	404	if (down_trylock(&dev->limit_sem)) {
	405	retval = -EAGAIN;
	406	goto exit;
	407	}
c8dd7709	408	}
ff906518	409
403dfb58	410	spin_lock_irq(&dev->err_lock);
3ae9da1c GKH	411	retval = dev->errors;
3ae9da1c GKH	412	if (retval < 0) {
403dfb58 ON	413	/* any error is reported once */
	414	dev->errors = 0;
	415	/* to preserve notifications about reset */
	416	retval = (retval == -EPIPE) ? retval : -EIO;
	417	}
	418	spin_unlock_irq(&dev->err_lock);
	419	if (retval < 0)
	420	goto error;
	421
1da177e4 LT	422	/* create a urb, and a buffer for it, and copy the data to the urb */
	423	urb = usb_alloc_urb(0, GFP_KERNEL);
	424	if (!urb) {
	425	retval = -ENOMEM;
	426	goto error;
	427	}
	428
997ea58e DM	429	buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
997ea58e DM	430	&urb->transfer_dma);
1da177e4 LT	431	if (!buf) {
	432	retval = -ENOMEM;
	433	goto error;
	434	}
	435
ff906518	436	if (copy_from_user(buf, user_buffer, writesize)) {
1da177e4 LT	437	retval = -EFAULT;
	438	goto error;
	439	}
	440
ba35e02b ON	441	/* this lock makes sure we don't submit URBs to gone devices */
	442	mutex_lock(&dev->io_mutex);
	443	if (!dev->interface) { /* disconnect() was called */
	444	mutex_unlock(&dev->io_mutex);
	445	retval = -ENODEV;
	446	goto error;
	447	}
	448
1da177e4 LT	449	/* initialize the urb properly */
	450	usb_fill_bulk_urb(urb, dev->udev,
	451	usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
ff906518	452	buf, writesize, skel_write_bulk_callback, dev);
1da177e4	453	urb->transfer_flags \|= URB_NO_TRANSFER_DMA_MAP;
403dfb58	454	usb_anchor_urb(urb, &dev->submitted);
1da177e4 LT	455
	456	/* send the data out the bulk port */
	457	retval = usb_submit_urb(urb, GFP_KERNEL);
ba35e02b	458	mutex_unlock(&dev->io_mutex);
1da177e4	459	if (retval) {
4212cd74 GKH	460	dev_err(&dev->interface->dev,
	461	"%s - failed submitting write urb, error %d\n",
	462	__func__, retval);
403dfb58	463	goto error_unanchor;
1da177e4 LT	464	}
1da177e4 LT	465
3ae9da1c GKH	466	/*
	467	* release our reference to this urb, the USB core will eventually free
	468	* it entirely
	469	*/
1da177e4 LT	470	usb_free_urb(urb);
1da177e4 LT	471
ba35e02b	472
ff906518	473	return writesize;
1da177e4	474
403dfb58 ON	475	error_unanchor:
403dfb58 ON	476	usb_unanchor_urb(urb);
1da177e4	477	error:
121e287c	478	if (urb) {
997ea58e	479	usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
121e287c AS	480	usb_free_urb(urb);
121e287c AS	481	}
ff906518	482	up(&dev->limit_sem);
121e287c AS	483
121e287c AS	484	exit:
1da177e4 LT	485	return retval;
	486	}
	487
066202dd	488	static const struct file_operations skel_fops = {
1da177e4 LT	489	.owner = THIS_MODULE,
	490	.read = skel_read,
	491	.write = skel_write,
	492	.open = skel_open,
	493	.release = skel_release,
403dfb58	494	.flush = skel_flush,
6038f373	495	.llseek = noop_llseek,
1da177e4 LT	496	};
1da177e4 LT	497
c0704541	498	/*
1da177e4	499	* usb class driver info in order to get a minor number from the usb core,
595b14cb	500	* and to have the device registered with the driver core
1da177e4 LT	501	*/
1da177e4 LT	502	static struct usb_class_driver skel_class = {
d6e5bcf4	503	.name = "skel%d",
1da177e4	504	.fops = &skel_fops,
1da177e4 LT	505	.minor_base = USB_SKEL_MINOR_BASE,
	506	};
	507
3ae9da1c GKH	508	static int skel_probe(struct usb_interface *interface,
3ae9da1c GKH	509	const struct usb_device_id *id)
1da177e4	510	{
c0704541	511	struct usb_skel *dev;
1da177e4 LT	512	struct usb_host_interface *iface_desc;
	513	struct usb_endpoint_descriptor *endpoint;
	514	size_t buffer_size;
	515	int i;
	516	int retval = -ENOMEM;
	517
	518	/* allocate memory for our device state and initialize it */
ff906518	519	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
c0704541	520	if (!dev) {
4212cd74	521	dev_err(&interface->dev, "Out of memory\n");
1da177e4 LT	522	goto error;
1da177e4 LT	523	}
1da177e4	524	kref_init(&dev->kref);
ff906518	525	sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
121e287c	526	mutex_init(&dev->io_mutex);
403dfb58 ON	527	spin_lock_init(&dev->err_lock);
403dfb58 ON	528	init_usb_anchor(&dev->submitted);
e7389cc9	529	init_completion(&dev->bulk_in_completion);
1da177e4 LT	530
	531	dev->udev = usb_get_dev(interface_to_usbdev(interface));
	532	dev->interface = interface;
	533
	534	/* set up the endpoint information */
	535	/* use only the first bulk-in and bulk-out endpoints */
	536	iface_desc = interface->cur_altsetting;
	537	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
	538	endpoint = &iface_desc->endpoint[i].desc;
	539
	540	if (!dev->bulk_in_endpointAddr &&
c0704541	541	usb_endpoint_is_bulk_in(endpoint)) {
1da177e4	542	/* we found a bulk in endpoint */
29cc8897	543	buffer_size = usb_endpoint_maxp(endpoint);
1da177e4 LT	544	dev->bulk_in_size = buffer_size;
	545	dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
	546	dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
	547	if (!dev->bulk_in_buffer) {
4212cd74 GKH	548	dev_err(&interface->dev,
4212cd74 GKH	549	"Could not allocate bulk_in_buffer\n");
1da177e4 LT	550	goto error;
1da177e4 LT	551	}
e7389cc9 ON	552	dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
e7389cc9 ON	553	if (!dev->bulk_in_urb) {
4212cd74 GKH	554	dev_err(&interface->dev,
4212cd74 GKH	555	"Could not allocate bulk_in_urb\n");
e7389cc9 ON	556	goto error;
e7389cc9 ON	557	}
1da177e4 LT	558	}
	559
	560	if (!dev->bulk_out_endpointAddr &&
c0704541	561	usb_endpoint_is_bulk_out(endpoint)) {
1da177e4 LT	562	/* we found a bulk out endpoint */
	563	dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
	564	}
	565	}
	566	if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
4212cd74 GKH	567	dev_err(&interface->dev,
4212cd74 GKH	568	"Could not find both bulk-in and bulk-out endpoints\n");
1da177e4 LT	569	goto error;
	570	}
	571
	572	/* save our data pointer in this interface device */
	573	usb_set_intfdata(interface, dev);
	574
	575	/* we can register the device now, as it is ready */
	576	retval = usb_register_dev(interface, &skel_class);
	577	if (retval) {
	578	/* something prevented us from registering this driver */
4212cd74 GKH	579	dev_err(&interface->dev,
4212cd74 GKH	580	"Not able to get a minor for this device.\n");
1da177e4 LT	581	usb_set_intfdata(interface, NULL);
	582	goto error;
	583	}
	584
	585	/* let the user know what node this device is now attached to */
a5f5ea23 MK	586	dev_info(&interface->dev,
	587	"USB Skeleton device now attached to USBSkel-%d",
	588	interface->minor);
1da177e4 LT	589	return 0;
	590
	591	error:
	592	if (dev)
ba35e02b	593	/* this frees allocated memory */
1da177e4 LT	594	kref_put(&dev->kref, skel_delete);
	595	return retval;
	596	}
	597
	598	static void skel_disconnect(struct usb_interface *interface)
	599	{
	600	struct usb_skel *dev;
	601	int minor = interface->minor;
	602
1da177e4	603	dev = usb_get_intfdata(interface);
52a74999	604	usb_set_intfdata(interface, NULL);
1da177e4 LT	605
	606	/* give back our minor */
	607	usb_deregister_dev(interface, &skel_class);
	608
121e287c AS	609	/* prevent more I/O from starting */
	610	mutex_lock(&dev->io_mutex);
	611	dev->interface = NULL;
	612	mutex_unlock(&dev->io_mutex);
	613
e73c7247 ON	614	usb_kill_anchored_urbs(&dev->submitted);
e73c7247 ON	615
1da177e4 LT	616	/* decrement our usage count */
	617	kref_put(&dev->kref, skel_delete);
	618
a5f5ea23	619	dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
1da177e4 LT	620	}
1da177e4 LT	621
403dfb58 ON	622	static void skel_draw_down(struct usb_skel *dev)
	623	{
	624	int time;
	625
	626	time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
	627	if (!time)
	628	usb_kill_anchored_urbs(&dev->submitted);
e7389cc9	629	usb_kill_urb(dev->bulk_in_urb);
403dfb58 ON	630	}
403dfb58 ON	631
758f7e16 ON	632	static int skel_suspend(struct usb_interface *intf, pm_message_t message)
	633	{
	634	struct usb_skel *dev = usb_get_intfdata(intf);
	635
	636	if (!dev)
	637	return 0;
	638	skel_draw_down(dev);
	639	return 0;
	640	}
	641
3ae9da1c	642	static int skel_resume(struct usb_interface *intf)
758f7e16 ON	643	{
	644	return 0;
	645	}
	646
87d093e2 ON	647	static int skel_pre_reset(struct usb_interface *intf)
	648	{
	649	struct usb_skel *dev = usb_get_intfdata(intf);
	650
	651	mutex_lock(&dev->io_mutex);
	652	skel_draw_down(dev);
	653
	654	return 0;
	655	}
	656
	657	static int skel_post_reset(struct usb_interface *intf)
	658	{
	659	struct usb_skel *dev = usb_get_intfdata(intf);
	660
	661	/* we are sure no URBs are active - no locking needed */
	662	dev->errors = -EPIPE;
	663	mutex_unlock(&dev->io_mutex);
	664
	665	return 0;
	666	}
	667
1da177e4	668	static struct usb_driver skel_driver = {
1da177e4 LT	669	.name = "skeleton",
	670	.probe = skel_probe,
	671	.disconnect = skel_disconnect,
758f7e16 ON	672	.suspend = skel_suspend,
758f7e16 ON	673	.resume = skel_resume,
87d093e2 ON	674	.pre_reset = skel_pre_reset,
87d093e2 ON	675	.post_reset = skel_post_reset,
1da177e4	676	.id_table = skel_table,
ba35e02b	677	.supports_autosuspend = 1,
1da177e4 LT	678	};
1da177e4 LT	679
65db4305	680	module_usb_driver(skel_driver);
1da177e4 LT	681
1da177e4 LT	682	MODULE_LICENSE("GPL");