text: /*
   * Gadget Function Driver for MTP
   *
   * Copyright (C) 2010 Google, Inc.
   * Author: Mike Lockwood <lockwood@android.com>
   *
   * This software is licensed under the terms of the GNU General Public
   * License version 2, as published by the Free Software Foundation, and
   * may be copied, distributed, and modified under those terms.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   */
  
  /* #define DEBUG */
  /* #define VERBOSE_DEBUG */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/poll.h>
  #include <linux/delay.h>
  #include <linux/wait.h>
  #include <linux/err.h>
  #include <linux/interrupt.h>
  
  #include <linux/seq_file.h>
  #include <linux/debugfs.h>
  #include <linux/types.h>
  #include <linux/file.h>
  #include <linux/device.h>
  #include <linux/miscdevice.h>
  #include <linux/ipc_logging.h>
  
  #include <linux/usb.h>
  #include <linux/usb_usual.h>
  #include <linux/usb/ch9.h>
  #include <linux/usb/f_mtp.h>
  #include <linux/configfs.h>
  #include <linux/usb/composite.h>
  
  #include "configfs.h"
  
  #define NUM_PAGES	10 /* # of pages for ipc logging */
  
  #ifdef CONFIG_DYNAMIC_DEBUG
  #define mtp_log(fmt, ...) do { \
  	ipc_log_string(_mtp_ipc_log, "%s: " fmt,  __func__, ##__VA_ARGS__); \
  	dynamic_pr_debug("%s: " fmt, __func__, ##__VA_ARGS__); \
  } while (0)
  #else
  #define mtp_log(fmt, ...) \
  	ipc_log_string(_mtp_ipc_log, "%s: " fmt,  __func__, ##__VA_ARGS__)
  #endif
  
  #define MTP_RX_BUFFER_INIT_SIZE    1048576
  #define MTP_TX_BUFFER_INIT_SIZE    1048576
  #define MTP_BULK_BUFFER_SIZE       16384
  #define INTR_BUFFER_SIZE           28
  #define MAX_INST_NAME_LEN          40
  #define MTP_MAX_FILE_SIZE          0xFFFFFFFFL
  
  /* String IDs */
  #define INTERFACE_STRING_INDEX	0
  
  /* values for mtp_dev.state */
  #define STATE_OFFLINE               0   /* initial state, disconnected */
  #define STATE_READY                 1   /* ready for userspace calls */
  #define STATE_BUSY                  2   /* processing userspace calls */
  #define STATE_CANCELED              3   /* transaction canceled by host */
  #define STATE_ERROR                 4   /* error from completion routine */
  
  /* number of tx and rx requests to allocate */
  #define MTP_TX_REQ_MAX 8
  #define RX_REQ_MAX 2
  #define INTR_REQ_MAX 5
  
  /* ID for Microsoft MTP OS String */
  #define MTP_OS_STRING_ID   0xEE
  
  /* MTP class reqeusts */
  #define MTP_REQ_CANCEL              0x64
  #define MTP_REQ_GET_EXT_EVENT_DATA  0x65
  #define MTP_REQ_RESET               0x66
  #define MTP_REQ_GET_DEVICE_STATUS   0x67
  
  /* constants for device status */
  #define MTP_RESPONSE_OK             0x2001
  #define MTP_RESPONSE_DEVICE_BUSY    0x2019
  #define DRIVER_NAME "mtp"
  
  #define MAX_ITERATION		100
  
  unsigned int mtp_rx_req_len = MTP_RX_BUFFER_INIT_SIZE;
  module_param(mtp_rx_req_len, uint, 0644);
  
  unsigned int mtp_tx_req_len = MTP_TX_BUFFER_INIT_SIZE;
  module_param(mtp_tx_req_len, uint, 0644);
  
  unsigned int mtp_tx_reqs = MTP_TX_REQ_MAX;
  module_param(mtp_tx_reqs, uint, 0644);
  
  static const char mtp_shortname[] = DRIVER_NAME "_usb";
  
  struct mtp_dev {
  	struct usb_function function;
  	struct usb_composite_dev *cdev;
  	spinlock_t lock;
  
  	struct usb_ep *ep_in;
  	struct usb_ep *ep_out;
  	struct usb_ep *ep_intr;
  
  	int state;
  
  	/* synchronize access to our device file */
  	atomic_t open_excl;
  	/* to enforce only one ioctl at a time */
  	atomic_t ioctl_excl;
  
  	struct list_head tx_idle;
  	struct list_head intr_idle;
  
  	wait_queue_head_t read_wq;
  	wait_queue_head_t write_wq;
  	wait_queue_head_t intr_wq;
  	struct usb_request *rx_req[RX_REQ_MAX];
  	int rx_done;
  
  	/* for processing MTP_SEND_FILE, MTP_RECEIVE_FILE and
  	 * MTP_SEND_FILE_WITH_HEADER ioctls on a work queue
  	 */
  	struct workqueue_struct *wq;
  	struct work_struct send_file_work;
  	struct work_struct receive_file_work;
  	struct file *xfer_file;
  	loff_t xfer_file_offset;
  	int64_t xfer_file_length;
  	unsigned xfer_send_header;
  	uint16_t xfer_command;
  	uint32_t xfer_transaction_id;
  	int xfer_result;
  	struct {
  		unsigned long vfs_rbytes;
  		unsigned long vfs_wbytes;
  		unsigned int vfs_rtime;
  		unsigned int vfs_wtime;
  	} perf[MAX_ITERATION];
  	unsigned int dbg_read_index;
  	unsigned int dbg_write_index;
  	unsigned int mtp_rx_req_len;
  	unsigned int mtp_tx_req_len;
  	unsigned int mtp_tx_reqs;
  	struct mutex  read_mutex;
  };
  
  static void *_mtp_ipc_log;
  
  static struct usb_interface_descriptor mtp_interface_desc = {
  	.bLength                = USB_DT_INTERFACE_SIZE,
  	.bDescriptorType        = USB_DT_INTERFACE,
  	.bInterfaceNumber       = 0,
  	.bNumEndpoints          = 3,
  	.bInterfaceClass        = USB_CLASS_VENDOR_SPEC,
  	.bInterfaceSubClass     = USB_SUBCLASS_VENDOR_SPEC,
  	.bInterfaceProtocol     = 0,
  };
  
  static struct usb_interface_descriptor ptp_interface_desc = {
  	.bLength                = USB_DT_INTERFACE_SIZE,
  	.bDescriptorType        = USB_DT_INTERFACE,
  	.bInterfaceNumber       = 0,
  	.bNumEndpoints          = 3,
  	.bInterfaceClass        = USB_CLASS_STILL_IMAGE,
  	.bInterfaceSubClass     = 1,
  	.bInterfaceProtocol     = 1,
  };
  
  static struct usb_endpoint_descriptor mtp_ss_in_desc = {
  	.bLength                = USB_DT_ENDPOINT_SIZE,
  	.bDescriptorType        = USB_DT_ENDPOINT,
  	.bEndpointAddress       = USB_DIR_IN,
  	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
  	.wMaxPacketSize         = __constant_cpu_to_le16(1024),
  };
  
  static struct usb_ss_ep_comp_descriptor mtp_ss_in_comp_desc = {
  	.bLength                = sizeof(mtp_ss_in_comp_desc),
  	.bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
  	/* .bMaxBurst           = DYNAMIC, */
  };
  
  static struct usb_endpoint_descriptor mtp_ss_out_desc = {
  	.bLength                = USB_DT_ENDPOINT_SIZE,
  	.bDescriptorType        = USB_DT_ENDPOINT,
  	.bEndpointAddress       = USB_DIR_OUT,
  	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
  	.wMaxPacketSize         = __constant_cpu_to_le16(1024),
  };
  
  static struct usb_ss_ep_comp_descriptor mtp_ss_out_comp_desc = {
  	.bLength                = sizeof(mtp_ss_out_comp_desc),
  	.bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
  	/* .bMaxBurst           = DYNAMIC, */
  };
  
  static struct usb_endpoint_descriptor mtp_highspeed_in_desc = {
  	.bLength                = USB_DT_ENDPOINT_SIZE,
  	.bDescriptorType        = USB_DT_ENDPOINT,
  	.bEndpointAddress       = USB_DIR_IN,
  	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
  	.wMaxPacketSize         = __constant_cpu_to_le16(512),
  };
  
  static struct usb_endpoint_descriptor mtp_highspeed_out_desc = {
  	.bLength                = USB_DT_ENDPOINT_SIZE,
  	.bDescriptorType        = USB_DT_ENDPOINT,
  	.bEndpointAddress       = USB_DIR_OUT,
  	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
  	.wMaxPacketSize         = __constant_cpu_to_le16(512),
  };
  
  static struct usb_endpoint_descriptor mtp_fullspeed_in_desc = {
  	.bLength                = USB_DT_ENDPOINT_SIZE,
  	.bDescriptorType        = USB_DT_ENDPOINT,
  	.bEndpointAddress       = USB_DIR_IN,
  	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
  };
  
  static struct usb_endpoint_descriptor mtp_fullspeed_out_desc = {
  	.bLength                = USB_DT_ENDPOINT_SIZE,
  	.bDescriptorType        = USB_DT_ENDPOINT,
  	.bEndpointAddress       = USB_DIR_OUT,
  	.bmAttributes           = USB_ENDPOINT_XFER_BULK,
  };
  
  static struct usb_endpoint_descriptor mtp_intr_desc = {
  	.bLength                = USB_DT_ENDPOINT_SIZE,
  	.bDescriptorType        = USB_DT_ENDPOINT,
  	.bEndpointAddress       = USB_DIR_IN,
  	.bmAttributes           = USB_ENDPOINT_XFER_INT,
  	.wMaxPacketSize         = __constant_cpu_to_le16(INTR_BUFFER_SIZE),
  	.bInterval              = 6,
  };
  
  static struct usb_ss_ep_comp_descriptor mtp_intr_ss_comp_desc = {
  	.bLength                = sizeof(mtp_intr_ss_comp_desc),
  	.bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
  	.wBytesPerInterval      = cpu_to_le16(INTR_BUFFER_SIZE),
  };
  
  static struct usb_descriptor_header *fs_mtp_descs[] = {
  	(struct usb_descriptor_header *) &mtp_interface_desc,
  	(struct usb_descriptor_header *) &mtp_fullspeed_in_desc,
  	(struct usb_descriptor_header *) &mtp_fullspeed_out_desc,
  	(struct usb_descriptor_header *) &mtp_intr_desc,
  	NULL,
  };
  
  static struct usb_descriptor_header *hs_mtp_descs[] = {
  	(struct usb_descriptor_header *) &mtp_interface_desc,
  	(struct usb_descriptor_header *) &mtp_highspeed_in_desc,
  	(struct usb_descriptor_header *) &mtp_highspeed_out_desc,
  	(struct usb_descriptor_header *) &mtp_intr_desc,
  	NULL,
  };
  
  static struct usb_descriptor_header *ss_mtp_descs[] = {
  	(struct usb_descriptor_header *) &mtp_interface_desc,
  	(struct usb_descriptor_header *) &mtp_ss_in_desc,
  	(struct usb_descriptor_header *) &mtp_ss_in_comp_desc,
  	(struct usb_descriptor_header *) &mtp_ss_out_desc,
  	(struct usb_descriptor_header *) &mtp_ss_out_comp_desc,
  	(struct usb_descriptor_header *) &mtp_intr_desc,
  	(struct usb_descriptor_header *) &mtp_intr_ss_comp_desc,
  	NULL,
  };
  
  static struct usb_descriptor_header *fs_ptp_descs[] = {
  	(struct usb_descriptor_header *) &ptp_interface_desc,
  	(struct usb_descriptor_header *) &mtp_fullspeed_in_desc,
  	(struct usb_descriptor_header *) &mtp_fullspeed_out_desc,
  	(struct usb_descriptor_header *) &mtp_intr_desc,
  	NULL,
  };
  
  static struct usb_descriptor_header *hs_ptp_descs[] = {
  	(struct usb_descriptor_header *) &ptp_interface_desc,
  	(struct usb_descriptor_header *) &mtp_highspeed_in_desc,
  	(struct usb_descriptor_header *) &mtp_highspeed_out_desc,
  	(struct usb_descriptor_header *) &mtp_intr_desc,
  	NULL,
  };
  
  static struct usb_descriptor_header *ss_ptp_descs[] = {
  	(struct usb_descriptor_header *) &ptp_interface_desc,
  	(struct usb_descriptor_header *) &mtp_ss_in_desc,
  	(struct usb_descriptor_header *) &mtp_ss_in_comp_desc,
  	(struct usb_descriptor_header *) &mtp_ss_out_desc,
  	(struct usb_descriptor_header *) &mtp_ss_out_comp_desc,
  	(struct usb_descriptor_header *) &mtp_intr_desc,
  	(struct usb_descriptor_header *) &mtp_intr_ss_comp_desc,
  	NULL,
  };
  
  static struct usb_string mtp_string_defs[] = {
  	/* Naming interface "MTP" so libmtp will recognize us */
  	[INTERFACE_STRING_INDEX].s	= "MTP",
  	{  },	/* end of list */
  };
  
  static struct usb_gadget_strings mtp_string_table = {
  	.language		= 0x0409,	/* en-US */
  	.strings		= mtp_string_defs,
  };
  
  static struct usb_gadget_strings *mtp_strings[] = {
  	&mtp_string_table,
  	NULL,
  };
  
  /* Microsoft MTP OS String */
  static u8 mtp_os_string[] = {
  	18, /* sizeof(mtp_os_string) */
  	USB_DT_STRING,
  	/* Signature field: "MSFT100" */
  	'M', 0, 'S', 0, 'F', 0, 'T', 0, '1', 0, '0', 0, '0', 0,
  	/* vendor code */
  	1,
  	/* padding */
  	0
  };
  
  /* Microsoft Extended Configuration Descriptor Header Section */
  struct mtp_ext_config_desc_header {
  	__le32	dwLength;
  	__u16	bcdVersion;
  	__le16	wIndex;
  	__u8	bCount;
  	__u8	reserved[7];
  };
  
  /* Microsoft Extended Configuration Descriptor Function Section */
  struct mtp_ext_config_desc_function {
  	__u8	bFirstInterfaceNumber;
  	__u8	bInterfaceCount;
  	__u8	compatibleID[8];
  	__u8	subCompatibleID[8];
  	__u8	reserved[6];
  };
  
  /* MTP Extended Configuration Descriptor */
  struct mtp_ext_config_desc {
  	struct mtp_ext_config_desc_header	header;
  	struct mtp_ext_config_desc_function    function;
  };
  
  static struct mtp_ext_config_desc mtp_ext_config_desc = {
  	.header = {
  		.dwLength = __constant_cpu_to_le32(sizeof(mtp_ext_config_desc)),
  		.bcdVersion = __constant_cpu_to_le16(0x0100),
  		.wIndex = __constant_cpu_to_le16(4),
  		.bCount = 1,
  	},
  	.function = {
  		.bFirstInterfaceNumber = 0,
  		.bInterfaceCount = 1,
  		.compatibleID = { 'M', 'T', 'P' },
  	},
  };
  
  struct mtp_device_status {
  	__le16	wLength;
  	__le16	wCode;
  };
  
  struct mtp_data_header {
  	/* length of packet, including this header */
  	__le32	length;
  	/* container type (2 for data packet) */
  	__le16	type;
  	/* MTP command code */
  	__le16	command;
  	/* MTP transaction ID */
  	__le32	transaction_id;
  };
  
  struct mtp_instance {
  	struct usb_function_instance func_inst;
  	const char *name;
  	struct mtp_dev *dev;
  	char mtp_ext_compat_id[16];
  	struct usb_os_desc mtp_os_desc;
  };
  
  /* temporary variable used between mtp_open() and mtp_gadget_bind() */
  static struct mtp_dev *_mtp_dev;
  
  static inline struct mtp_dev *func_to_mtp(struct usb_function *f)
  {
  	return container_of(f, struct mtp_dev, function);
  }
  
  static struct usb_request *mtp_request_new(struct usb_ep *ep, int buffer_size)
  {
  	struct usb_request *req = usb_ep_alloc_request(ep, GFP_KERNEL);
  
  	if (!req)
  		return NULL;
  
  	/* now allocate buffers for the requests */
  	req->buf = kmalloc(buffer_size, GFP_KERNEL);
  	if (!req->buf) {
  		usb_ep_free_request(ep, req);
  		return NULL;
  	}
  
  	return req;
  }
  
  static void mtp_request_free(struct usb_request *req, struct usb_ep *ep)
  {
  	if (req) {
  		kfree(req->buf);
  		usb_ep_free_request(ep, req);
  	}
  }
  
  static inline int mtp_lock(atomic_t *excl)
  {
  	if (atomic_inc_return(excl) == 1) {
  		return 0;
  	} else {
  		atomic_dec(excl);
  		return -1;
  	}
  }
  
  static inline void mtp_unlock(atomic_t *excl)
  {
  	atomic_dec(excl);
  }
  
  /* add a request to the tail of a list */
  static void mtp_req_put(struct mtp_dev *dev, struct list_head *head,
  		struct usb_request *req)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&dev->lock, flags);
  	list_add_tail(&req->list, head);
  	spin_unlock_irqrestore(&dev->lock, flags);
  }
  
  /* remove a request from the head of a list */
  static struct usb_request
  *mtp_req_get(struct mtp_dev *dev, struct list_head *head)
  {
  	unsigned long flags;
  	struct usb_request *req;
  
  	spin_lock_irqsave(&dev->lock, flags);
  	if (list_empty(head)) {
  		req = 0;
  	} else {
  		req = list_first_entry(head, struct usb_request, list);
  		list_del(&req->list);
  	}
  	spin_unlock_irqrestore(&dev->lock, flags);
  	return req;
  }
  
  static void mtp_complete_in(struct usb_ep *ep, struct usb_request *req)
  {
  	struct mtp_dev *dev = _mtp_dev;
  
  	if (req->status != 0 && dev->state != STATE_OFFLINE)
  		dev->state = STATE_ERROR;
  
  	mtp_req_put(dev, &dev->tx_idle, req);
  
  	wake_up(&dev->write_wq);
  }
  
  static void mtp_complete_out(struct usb_ep *ep, struct usb_request *req)
  {
  	struct mtp_dev *dev = _mtp_dev;
  
  	dev->rx_done = 1;
  	if (req->status != 0 && dev->state != STATE_OFFLINE)
  		dev->state = STATE_ERROR;
  
  	wake_up(&dev->read_wq);
  }
  
  static void mtp_complete_intr(struct usb_ep *ep, struct usb_request *req)
  {
  	struct mtp_dev *dev = _mtp_dev;
  
  	if (req->status != 0 && dev->state != STATE_OFFLINE)
  		dev->state = STATE_ERROR;
  
  	mtp_req_put(dev, &dev->intr_idle, req);
  
  	wake_up(&dev->intr_wq);
  }
  
  static int mtp_create_bulk_endpoints(struct mtp_dev *dev,
  				struct usb_endpoint_descriptor *in_desc,
  				struct usb_endpoint_descriptor *out_desc,
  				struct usb_endpoint_descriptor *intr_desc)
  {
  	struct usb_composite_dev *cdev = dev->cdev;
  	struct usb_request *req;
  	struct usb_ep *ep;
  	size_t extra_buf_alloc = cdev->gadget->extra_buf_alloc;
  	int i;
  
  	mtp_log("dev: %pK\n", dev);
  
  	ep = usb_ep_autoconfig(cdev->gadget, in_desc);
  	if (!ep) {
  		mtp_log("usb_ep_autoconfig for ep_in failed\n");
  		return -ENODEV;
  	}
  	mtp_log("usb_ep_autoconfig for ep_in got %s\n", ep->name);
  	ep->driver_data = dev;		/* claim the endpoint */
  	dev->ep_in = ep;
  
  	ep = usb_ep_autoconfig(cdev->gadget, out_desc);
  	if (!ep) {
  		mtp_log("usb_ep_autoconfig for ep_out failed\n");
  		return -ENODEV;
  	}
  	mtp_log("usb_ep_autoconfig for mtp ep_out got %s\n", ep->name);
  	ep->driver_data = dev;		/* claim the endpoint */
  	dev->ep_out = ep;
  
  	ep = usb_ep_autoconfig(cdev->gadget, intr_desc);
  	if (!ep) {
  		mtp_log("usb_ep_autoconfig for ep_intr failed\n");
  		return -ENODEV;
  	}
  	mtp_log("usb_ep_autoconfig for mtp ep_intr got %s\n", ep->name);
  	ep->driver_data = dev;		/* claim the endpoint */
  	dev->ep_intr = ep;
  
  retry_tx_alloc:
  	/* now allocate requests for our endpoints */
  	for (i = 0; i < dev->mtp_tx_reqs; i++) {
  		req = mtp_request_new(dev->ep_in,
  				dev->mtp_tx_req_len + extra_buf_alloc);
  		if (!req) {
  			if (dev->mtp_tx_req_len <= MTP_BULK_BUFFER_SIZE)
  				goto fail;
  			while ((req = mtp_req_get(dev, &dev->tx_idle)))
  				mtp_request_free(req, dev->ep_in);
  			dev->mtp_tx_req_len = MTP_BULK_BUFFER_SIZE;
  			dev->mtp_tx_reqs = MTP_TX_REQ_MAX;
  			goto retry_tx_alloc;
  		}
  		req->complete = mtp_complete_in;
  		mtp_req_put(dev, &dev->tx_idle, req);
  	}
  
  	/*
  	 * The RX buffer should be aligned to EP max packet for
  	 * some controllers.  At bind time, we don't know the
  	 * operational speed.  Hence assuming super speed max
  	 * packet size.
  	 */
  	if (dev->mtp_rx_req_len % 1024)
  		dev->mtp_rx_req_len = MTP_BULK_BUFFER_SIZE;
  
  retry_rx_alloc:
  	for (i = 0; i < RX_REQ_MAX; i++) {
  		req = mtp_request_new(dev->ep_out, dev->mtp_rx_req_len);
  		if (!req) {
  			if (dev->mtp_rx_req_len <= MTP_BULK_BUFFER_SIZE)
  				goto fail;
  			for (--i; i >= 0; i--)
  				mtp_request_free(dev->rx_req[i], dev->ep_out);
  			dev->mtp_rx_req_len = MTP_BULK_BUFFER_SIZE;
  			goto retry_rx_alloc;
  		}
  		req->complete = mtp_complete_out;
  		dev->rx_req[i] = req;
  	}
  	for (i = 0; i < INTR_REQ_MAX; i++) {
  		req = mtp_request_new(dev->ep_intr,
  				INTR_BUFFER_SIZE + extra_buf_alloc);
  		if (!req)
  			goto fail;
  		req->complete = mtp_complete_intr;
  		mtp_req_put(dev, &dev->intr_idle, req);
  	}
  
  	return 0;
  
  fail:
  	pr_err("mtp_bind() could not allocate requests\n");
  	return -1;
  }
  
  static ssize_t mtp_read(struct file *fp, char __user *buf,
  	size_t count, loff_t *pos)
  {
  	struct mtp_dev *dev = fp->private_data;
  	struct usb_composite_dev *cdev = dev->cdev;
  	struct usb_request *req;
  	ssize_t r = count;
  	unsigned xfer;
  	int ret = 0;
  	size_t len = 0;
  
  	mtp_log("(%zu) state:%d\n", count, dev->state);
  
  	/* we will block until we're online */
  	mtp_log("waiting for online state\n");
  	ret = wait_event_interruptible(dev->read_wq,
  		dev->state != STATE_OFFLINE);
  	if (ret < 0) {
  		r = ret;
  		goto done;
  	}
  
  	len = ALIGN(count, dev->ep_out->maxpacket);
  	if (len > dev->mtp_rx_req_len)
  		return -EINVAL;
  
  	spin_lock_irq(&dev->lock);
  	if (dev->state == STATE_OFFLINE) {
  		spin_unlock_irq(&dev->lock);
  		return -ENODEV;
  	}
  
  	if (dev->ep_out->desc) {
  		if (!cdev) {
  			spin_unlock_irq(&dev->lock);
  			return -ENODEV;
  		}
  
  		len = usb_ep_align_maybe(cdev->gadget, dev->ep_out, count);
  		if (len > MTP_BULK_BUFFER_SIZE) {
  			spin_unlock_irq(&dev->lock);
  			return -EINVAL;
  		}
  	}
  
  	if (dev->state == STATE_CANCELED) {
  		/* report cancelation to userspace */
  		dev->state = STATE_READY;
  		spin_unlock_irq(&dev->lock);
  		return -ECANCELED;
  	}
  	dev->state = STATE_BUSY;
  	spin_unlock_irq(&dev->lock);
  
  	mutex_lock(&dev->read_mutex);
  	if (dev->state == STATE_OFFLINE) {
  		r = -EIO;
  		mutex_unlock(&dev->read_mutex);
  		goto done;
  	}
  requeue_req:
  	/* queue a request */
  	req = dev->rx_req[0];
  	req->length = len;
  	dev->rx_done = 0;
  	mutex_unlock(&dev->read_mutex);
  	ret = usb_ep_queue(dev->ep_out, req, GFP_KERNEL);
  	if (ret < 0) {
  		r = -EIO;
  		goto done;
  	} else {
  		mtp_log("rx %pK queue\n", req);
  	}
  
  	/* wait for a request to complete */
  	ret = wait_event_interruptible(dev->read_wq,
  				dev->rx_done || dev->state != STATE_BUSY);
  	if (dev->state == STATE_CANCELED) {
  		r = -ECANCELED;
  		if (!dev->rx_done)
  			usb_ep_dequeue(dev->ep_out, req);
  		spin_lock_irq(&dev->lock);
  		dev->state = STATE_CANCELED;
  		spin_unlock_irq(&dev->lock);
  		goto done;
  	}
  	if (ret < 0) {
  		r = ret;
  		usb_ep_dequeue(dev->ep_out, req);
  		goto done;
  	}
  	mutex_lock(&dev->read_mutex);
  	if (dev->state == STATE_BUSY) {
  		/* If we got a 0-len packet, throw it back and try again. */
  		if (req->actual == 0)
  			goto requeue_req;
  
  		mtp_log("rx %pK %d\n", req, req->actual);
  		xfer = (req->actual < count) ? req->actual : count;
  		r = xfer;
  		if (copy_to_user(buf, req->buf, xfer))
  			r = -EFAULT;
  	} else
  		r = -EIO;
  
  	mutex_unlock(&dev->read_mutex);
  done:
  	spin_lock_irq(&dev->lock);
  	if (dev->state == STATE_CANCELED)
  		r = -ECANCELED;
  	else if (dev->state != STATE_OFFLINE)
  		dev->state = STATE_READY;
  	spin_unlock_irq(&dev->lock);
  
  	mtp_log("returning %zd state:%d\n", r, dev->state);
  	return r;
  }
  
  static ssize_t mtp_write(struct file *fp, const char __user *buf,
  	size_t count, loff_t *pos)
  {
  	struct mtp_dev *dev = fp->private_data;
  	struct usb_request *req = 0;
  	ssize_t r = count;
  	unsigned xfer;
  	int sendZLP = 0;
  	int ret;
  
  	mtp_log("(%zu) state:%d\n", count, dev->state);
  
  	spin_lock_irq(&dev->lock);
  	if (dev->state == STATE_CANCELED) {
  		/* report cancelation to userspace */
  		dev->state = STATE_READY;
  		spin_unlock_irq(&dev->lock);
  		return -ECANCELED;
  	}
  	if (dev->state == STATE_OFFLINE) {
  		spin_unlock_irq(&dev->lock);
  		return -ENODEV;
  	}
  	dev->state = STATE_BUSY;
  	spin_unlock_irq(&dev->lock);
  
  	/* we need to send a zero length packet to signal the end of transfer
  	 * if the transfer size is aligned to a packet boundary.
  	 */
  	if ((count & (dev->ep_in->maxpacket - 1)) == 0)
  		sendZLP = 1;
  
  	while (count > 0 || sendZLP) {
  		/* so we exit after sending ZLP */
  		if (count == 0)
  			sendZLP = 0;
  
  		if (dev->state != STATE_BUSY) {
  			mtp_log("dev->error\n");
  			r = -EIO;
  			break;
  		}
  
  		/* get an idle tx request to use */
  		req = 0;
  		ret = wait_event_interruptible(dev->write_wq,
  			((req = mtp_req_get(dev, &dev->tx_idle))
  				|| dev->state != STATE_BUSY));
  		if (!req) {
  			mtp_log("request NULL ret:%d state:%d\n",
  				ret, dev->state);
  			r = ret;
  			break;
  		}
  
  		if (count > dev->mtp_tx_req_len)
  			xfer = dev->mtp_tx_req_len;
  		else
  			xfer = count;
  		if (xfer && copy_from_user(req->buf, buf, xfer)) {
  			r = -EFAULT;
  			break;
  		}
  
  		req->length = xfer;
  		ret = usb_ep_queue(dev->ep_in, req, GFP_KERNEL);
  		if (ret < 0) {
  			mtp_log("xfer error %d\n", ret);
  			r = -EIO;
  			break;
  		}
  
  		buf += xfer;
  		count -= xfer;
  
  		/* zero this so we don't try to free it on error exit */
  		req = 0;
  	}
  
  	if (req)
  		mtp_req_put(dev, &dev->tx_idle, req);
  
  	spin_lock_irq(&dev->lock);
  	if (dev->state == STATE_CANCELED)
  		r = -ECANCELED;
  	else if (dev->state != STATE_OFFLINE)
  		dev->state = STATE_READY;
  	spin_unlock_irq(&dev->lock);
  
  	mtp_log("returning %zd state:%d\n", r, dev->state);
  	return r;
  }
  
  /* read from a local file and write to USB */
  static void send_file_work(struct work_struct *data)
  {
  	struct mtp_dev *dev = container_of(data, struct mtp_dev,
  						send_file_work);
  	struct usb_request *req = 0;
  	struct mtp_data_header *header;
  	struct file *filp;
  	loff_t offset;
  	int64_t count;
  	int xfer, ret, hdr_size;
  	int r = 0;
  	int sendZLP = 0;
  	ktime_t start_time;
  
  	/* read our parameters */
  	smp_rmb();
  	filp = dev->xfer_file;
  	offset = dev->xfer_file_offset;
  	count = dev->xfer_file_length;
  
  	if (count < 0) {
  		dev->xfer_result = -EINVAL;
  		return;
  	}
  
  	mtp_log("(%lld %lld)\n", offset, count);
  
  	if (dev->xfer_send_header) {
  		hdr_size = sizeof(struct mtp_data_header);
  		count += hdr_size;
  	} else {
  		hdr_size = 0;
  	}
  
  	/* we need to send a zero length packet to signal the end of transfer
  	 * if the transfer size is aligned to a packet boundary.
  	 */
  	if ((count & (dev->ep_in->maxpacket - 1)) == 0)
  		sendZLP = 1;
  
  	while (count > 0 || sendZLP) {
  		/* so we exit after sending ZLP */
  		if (count == 0)
  			sendZLP = 0;
  
  		/* get an idle tx request to use */
  		req = 0;
  		ret = wait_event_interruptible(dev->write_wq,
  			(req = mtp_req_get(dev, &dev->tx_idle))
  			|| dev->state != STATE_BUSY);
  		if (dev->state == STATE_CANCELED) {
  			r = -ECANCELED;
  			break;
  		}
  		if (!req) {
  			mtp_log("request NULL ret:%d state:%d\n",
  				ret, dev->state);
  			r = ret;
  			break;
  		}
  
  		if (count > dev->mtp_tx_req_len)
  			xfer = dev->mtp_tx_req_len;
  		else
  			xfer = count;
  
  		if (hdr_size) {
  			/* prepend MTP data header */
  			header = (struct mtp_data_header *)req->buf;
  			/*
                           * set file size with header according to
                           * MTP Specification v1.0
                           */
  			header->length = (count > MTP_MAX_FILE_SIZE) ?
  				MTP_MAX_FILE_SIZE : __cpu_to_le32(count);
  			header->type = __cpu_to_le16(2); /* data packet */
  			header->command = __cpu_to_le16(dev->xfer_command);
  			header->transaction_id =
  					__cpu_to_le32(dev->xfer_transaction_id);
  		}
  		start_time = ktime_get();
  		ret = vfs_read(filp, req->buf + hdr_size, xfer - hdr_size,
  								&offset);
  		if (ret < 0) {
  			r = ret;
  			break;
  		}
  
  		xfer = ret + hdr_size;
  		dev->perf[dev->dbg_read_index].vfs_rtime =
  			ktime_to_us(ktime_sub(ktime_get(), start_time));
  		dev->perf[dev->dbg_read_index].vfs_rbytes = xfer;
  		dev->dbg_read_index = (dev->dbg_read_index + 1) % MAX_ITERATION;
  		hdr_size = 0;
  
  		req->length = xfer;
  		ret = usb_ep_queue(dev->ep_in, req, GFP_KERNEL);
  		if (ret < 0) {
  			mtp_log("xfer error %d\n", ret);
  			if (dev->state != STATE_OFFLINE)
  				dev->state = STATE_ERROR;
  			r = -EIO;
  			break;
  		}
  
  		count -= xfer;
  
  		/* zero this so we don't try to free it on error exit */
  		req = 0;
  	}
  
  	if (req)
  		mtp_req_put(dev, &dev->tx_idle, req);
  
  	mtp_log("returning %d state:%d\n", r, dev->state);
  	/* write the result */
  	dev->xfer_result = r;
  	smp_wmb();
  }
  
  /* read from USB and write to a local file */
  static void receive_file_work(struct work_struct *data)
  {
  	struct mtp_dev *dev = container_of(data, struct mtp_dev,
  						receive_file_work);
  	struct usb_request *read_req = NULL, *write_req = NULL;
  	struct file *filp;
  	loff_t offset;
  	int64_t count;
  	int ret, cur_buf = 0;
  	int r = 0;
  	ktime_t start_time;
  
  	/* read our parameters */
  	smp_rmb();
  	filp = dev->xfer_file;
  	offset = dev->xfer_file_offset;
  	count = dev->xfer_file_length;
  
  	if (count < 0) {
  		dev->xfer_result = -EINVAL;
  		return;
  	}
  
  	mtp_log("(%lld)\n", count);
  	if (!IS_ALIGNED(count, dev->ep_out->maxpacket))
  		mtp_log("- count(%lld) not multiple of mtu(%d)\n",
  						count, dev->ep_out->maxpacket);
  
  	while (count > 0 || write_req) {
  		if (count > 0) {
  			mutex_lock(&dev->read_mutex);
  			if (dev->state == STATE_OFFLINE) {
  				r = -EIO;
  				mutex_unlock(&dev->read_mutex);
  				break;
  			}
  			/* queue a request */
  			read_req = dev->rx_req[cur_buf];
  			cur_buf = (cur_buf + 1) % RX_REQ_MAX;
  
  			/* some h/w expects size to be aligned to ep's MTU */
  			read_req->length = dev->mtp_rx_req_len;
  
  			dev->rx_done = 0;
  			mutex_unlock(&dev->read_mutex);
  			ret = usb_ep_queue(dev->ep_out, read_req, GFP_KERNEL);
  			if (ret < 0) {
  				r = -EIO;
  				if (dev->state != STATE_OFFLINE)
  					dev->state = STATE_ERROR;
  				break;
  			}
  		}
  
  		if (write_req) {
  			mtp_log("rx %pK %d\n", write_req, write_req->actual);
  			start_time = ktime_get();
  			mutex_lock(&dev->read_mutex);
  			if (dev->state == STATE_OFFLINE) {
  				r = -EIO;
  				mutex_unlock(&dev->read_mutex);
  				break;
  			}
  			ret = vfs_write(filp, write_req->buf, write_req->actual,
  				&offset);
  			mtp_log("vfs_write %d\n", ret);
  			if (ret != write_req->actual) {
  				r = -EIO;
  				mutex_unlock(&dev->read_mutex);
  				if (dev->state != STATE_OFFLINE)
  					dev->state = STATE_ERROR;
  				break;
  			}
  			mutex_unlock(&dev->read_mutex);
  			dev->perf[dev->dbg_write_index].vfs_wtime =
  				ktime_to_us(ktime_sub(ktime_get(), start_time));
  			dev->perf[dev->dbg_write_index].vfs_wbytes = ret;
  			dev->dbg_write_index =
  				(dev->dbg_write_index + 1) % MAX_ITERATION;
  			write_req = NULL;
  		}
  
  		if (read_req) {
  			/* wait for our last read to complete */
  			ret = wait_event_interruptible(dev->read_wq,
  				dev->rx_done || dev->state != STATE_BUSY);
  			if (dev->state == STATE_CANCELED
  					|| dev->state == STATE_OFFLINE) {
  				if (dev->state == STATE_OFFLINE)
  					r = -EIO;
  				else
  					r = -ECANCELED;
  				if (!dev->rx_done)
  					usb_ep_dequeue(dev->ep_out, read_req);
  				break;
  			}
  
  			if (read_req->status) {
  				r = read_req->status;
  				break;
  			}
  
  			mutex_lock(&dev->read_mutex);
  			if (dev->state == STATE_OFFLINE) {
  				r = -EIO;
  				mutex_unlock(&dev->read_mutex);
  				break;
  			}
  			/* Check if we aligned the size due to MTU constraint */
  			if (count < read_req->length)
  				read_req->actual = (read_req->actual > count ?
  						count : read_req->actual);
  			/* if xfer_file_length is 0xFFFFFFFF, then we read until
  			 * we get a zero length packet
  			 */
  			if (count != 0xFFFFFFFF)
  				count -= read_req->actual;
  			if (read_req->actual < read_req->length) {
  				/*
  				 * short packet is used to signal EOF for
  				 * sizes > 4 gig
  				 */
  				mtp_log("got short packet\n");
  				count = 0;
  			}
  
  			write_req = read_req;
  			read_req = NULL;
  			mutex_unlock(&dev->read_mutex);
  		}
  	}
  
  	mtp_log("returning %d\n", r);
  	/* write the result */
  	dev->xfer_result = r;
  	smp_wmb();
  }
  
  static int mtp_send_event(struct mtp_dev *dev, struct mtp_event *event)
  {
  	struct usb_request *req = NULL;
  	int ret;
  	int length = event->length;
  
  	mtp_log("(%zu)\n", event->length);
  
  	if (length < 0 || length > INTR_BUFFER_SIZE)
  		return -EINVAL;
  	if (dev->state == STATE_OFFLINE)
  		return -ENODEV;
  
  	ret = wait_event_interruptible_timeout(dev->intr_wq,
  			(req = mtp_req_get(dev, &dev->intr_idle)),
  			msecs_to_jiffies(1000));
  	if (!req)
  		return -ETIME;
  
  	if (copy_from_user(req->buf, (void __user *)event->data, length)) {
  		mtp_req_put(dev, &dev->intr_idle, req);
  		return -EFAULT;
  	}
  	req->length = length;
  	ret = usb_ep_queue(dev->ep_intr, req, GFP_KERNEL);
  	if (ret)
  		mtp_req_put(dev, &dev->intr_idle, req);
  
  	return ret;
  }
  
  static long mtp_send_receive_ioctl(struct file *fp, unsigned int code,
  	struct mtp_file_range *mfr)
  {
  	struct mtp_dev *dev = fp->private_data;
  	struct file *filp = NULL;
  	struct work_struct *work;
  	int ret = -EINVAL;
  
  	if (mtp_lock(&dev->ioctl_excl)) {
  		mtp_log("ioctl returning EBUSY state:%d\n", dev->state);
  		return -EBUSY;
  	}
  
  	spin_lock_irq(&dev->lock);
  	if (dev->state == STATE_CANCELED) {
  		/* report cancellation to userspace */
  		dev->state = STATE_READY;
  		spin_unlock_irq(&dev->lock);
  		ret = -ECANCELED;
  		goto out;
  	}
  	if (dev->state == STATE_OFFLINE) {
  		spin_unlock_irq(&dev->lock);
  		ret = -ENODEV;
  		goto out;
  	}
  	dev->state = STATE_BUSY;
  	spin_unlock_irq(&dev->lock);
  
  	/* hold a reference to the file while we are working with it */
  	filp = fget(mfr->fd);
  	if (!filp) {
  		ret = -EBADF;
  		goto fail;
  	}
  
  	/* write the parameters */
  	dev->xfer_file = filp;
  	dev->xfer_file_offset = mfr->offset;
  	dev->xfer_file_length = mfr->length;
  	/* make sure write is done before parameters are read */
  	smp_wmb();
  
  	if (code == MTP_SEND_FILE_WITH_HEADER) {
  		work = &dev->send_file_work;
  		dev->xfer_send_header = 1;
  		dev->xfer_command = mfr->command;
  		dev->xfer_transaction_id = mfr->transaction_id;
  	} else if (code == MTP_SEND_FILE) {
  		work = &dev->send_file_work;
  		dev->xfer_send_header = 0;
  	} else {
  		work = &dev->receive_file_work;
  	}
  
  	/* We do the file transfer on a work queue so it will run
  	 * in kernel context, which is necessary for vfs_read and
  	 * vfs_write to use our buffers in the kernel address space.
  	 */
  	queue_work(dev->wq, work);
  	/* wait for operation to complete */
  	flush_workqueue(dev->wq);
  	fput(filp);
  
  	/* read the result */
  	smp_rmb();
  	ret = dev->xfer_result;
  
  fail:
  	spin_lock_irq(&dev->lock);
  	if (dev->state == STATE_CANCELED)
  		ret = -ECANCELED;
  	else if (dev->state != STATE_OFFLINE)
  		dev->state = STATE_READY;
  	spin_unlock_irq(&dev->lock);
  out:
  	mtp_unlock(&dev->ioctl_excl);
  	mtp_log("ioctl returning %d\n", ret);
  	return ret;
  }
  
  static long mtp_ioctl(struct file *fp, unsigned int code, unsigned long value)
  {
  	struct mtp_dev *dev = fp->private_data;
  	struct mtp_file_range	mfr;
  	struct mtp_event	event;
  	int ret = -EINVAL;
  
  	switch (code) {
  	case MTP_SEND_FILE:
  	case MTP_RECEIVE_FILE:
  	case MTP_SEND_FILE_WITH_HEADER:
  		if (copy_from_user(&mfr, (void __user *)value, sizeof(mfr))) {
  			ret = -EFAULT;
  			goto fail;
  		}
  		ret = mtp_send_receive_ioctl(fp, code, &mfr);
  	break;
  	case MTP_SEND_EVENT:
  		if (mtp_lock(&dev->ioctl_excl))
  			return -EBUSY;
  		/* return here so we don't change dev->state below,
  		 * which would interfere with bulk transfer state.
  		 */
  		if (copy_from_user(&event, (void __user *)value, sizeof(event)))
  			ret = -EFAULT;
  		else
  			ret = mtp_send_event(dev, &event);
  		mtp_unlock(&dev->ioctl_excl);
  	break;
  	default:
  		mtp_log("unknown ioctl code: %d\n", code);
  	}
  fail:
  	return ret;
  }
  
  /*
   * 32 bit userspace calling into 64 bit kernel. handle ioctl code
   * and userspace pointer
   */
  #ifdef CONFIG_COMPAT
  static long compat_mtp_ioctl(struct file *fp, unsigned int code,
  	unsigned long value)
  {
  	struct mtp_dev *dev = fp->private_data;
  	struct mtp_file_range	mfr;
  	struct __compat_mtp_file_range	cmfr;
  	struct mtp_event	event;
  	struct __compat_mtp_event cevent;
  	unsigned int cmd;
  	bool send_file = false;
  	int ret = -EINVAL;
  
  	switch (code) {
  	case COMPAT_MTP_SEND_FILE:
  		cmd = MTP_SEND_FILE;
  		send_file = true;
  		break;
  	case COMPAT_MTP_RECEIVE_FILE:
  		cmd = MTP_RECEIVE_FILE;
  		send_file = true;
  		break;
  	case COMPAT_MTP_SEND_FILE_WITH_HEADER:
  		cmd = MTP_SEND_FILE_WITH_HEADER;
  		send_file = true;
  		break;
  	case COMPAT_MTP_SEND_EVENT:
  		cmd = MTP_SEND_EVENT;
  		break;
  	default:
  		mtp_log("unknown compat_ioctl code: %d\n", code);
  		ret = -ENOIOCTLCMD;
  		goto fail;
  	}
  
  	if (send_file) {
  		if (copy_from_user(&cmfr, (void __user *)value, sizeof(cmfr))) {
  			ret = -EFAULT;
  			goto fail;
  		}
  		mfr.fd = cmfr.fd;
  		mfr.offset = cmfr.offset;
  		mfr.length = cmfr.length;
  		mfr.command = cmfr.command;
  		mfr.transaction_id = cmfr.transaction_id;
  		ret = mtp_send_receive_ioctl(fp, cmd, &mfr);
  	} else {
  		if (mtp_lock(&dev->ioctl_excl))
  			return -EBUSY;
  		/* return here so we don't change dev->state below,
  		 * which would interfere with bulk transfer state.
  		 */
  		if (copy_from_user(&cevent, (void __user *)value,
  			sizeof(cevent))) {
  			ret = -EFAULT;
  			goto fail;
  		}
  		event.length = cevent.length;
  		event.data = compat_ptr(cevent.data);
  		ret = mtp_send_event(dev, &event);
  		mtp_unlock(&dev->ioctl_excl);
  	}
  fail:
  	return ret;
  }
  #endif
  
  static int mtp_open(struct inode *ip, struct file *fp)
  {
  	printk(KERN_INFO "mtp_open\n");
  	if (mtp_lock(&_mtp_dev->open_excl)) {
  		pr_err("%s mtp_release not called returning EBUSY\n", __func__);
  		return -EBUSY;
  	}
  
  	/* clear any error condition */
  	if (_mtp_dev->state != STATE_OFFLINE)
  		_mtp_dev->state = STATE_READY;
  
  	fp->private_data = _mtp_dev;
  	return 0;
  }
  
  static int mtp_release(struct inode *ip, struct file *fp)
  {
  	printk(KERN_INFO "mtp_release\n");
  
  	mtp_unlock(&_mtp_dev->open_excl);
  	return 0;
  }
  
  /* file operations for /dev/mtp_usb */
  static const struct file_operations mtp_fops = {
  	.owner = THIS_MODULE,
  	.read = mtp_read,
  	.write = mtp_write,
  	.unlocked_ioctl = mtp_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl = compat_mtp_ioctl,
  #endif
  	.open = mtp_open,
  	.release = mtp_release,
  };
  
  static struct miscdevice mtp_device = {
  	.minor = MISC_DYNAMIC_MINOR,
  	.name = mtp_shortname,
  	.fops = &mtp_fops,
  };
  
  static int mtp_ctrlrequest(struct usb_composite_dev *cdev,
  				const struct usb_ctrlrequest *ctrl)
  {
  	struct mtp_dev *dev = _mtp_dev;
  	int	value = -EOPNOTSUPP;
  	u16	w_index = le16_to_cpu(ctrl->wIndex);
  	u16	w_value = le16_to_cpu(ctrl->wValue);
  	u16	w_length = le16_to_cpu(ctrl->wLength);
  	unsigned long	flags;
  
  	mtp_log("%02x.%02x v%04x i%04x l%u\n",
  			ctrl->bRequestType, ctrl->bRequest,
  			w_value, w_index, w_length);
  
  	/* Handle MTP OS string */
  	if (ctrl->bRequestType ==
  			(USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE)
  			&& ctrl->bRequest == USB_REQ_GET_DESCRIPTOR
  			&& (w_value >> 8) == USB_DT_STRING
  			&& (w_value & 0xFF) == MTP_OS_STRING_ID) {
  		value = (w_length < sizeof(mtp_os_string)
  				? w_length : sizeof(mtp_os_string));
  		memcpy(cdev->req->buf, mtp_os_string, value);
  	} else if ((ctrl->bRequestType & USB_TYPE_MASK) == USB_TYPE_VENDOR) {
  		/* Handle MTP OS descriptor */
  		mtp_log("vendor request: %d index: %d value: %d length: %d\n",
  			ctrl->bRequest, w_index, w_value, w_length);
  
  		if (ctrl->bRequest == 1
  				&& (ctrl->bRequestType & USB_DIR_IN)
  				&& (w_index == 4 || w_index == 5)) {
  			value = (w_length < sizeof(mtp_ext_config_desc) ?
  					w_length : sizeof(mtp_ext_config_desc));
  			memcpy(cdev->req->buf, &mtp_ext_config_desc, value);
  
  			/* update compatibleID if PTP */
  			if (dev->function.fs_descriptors == fs_ptp_descs) {
  				struct mtp_ext_config_desc *d = cdev->req->buf;
  
  				d->function.compatibleID[0] = 'P';
  			}
  		}
  	} else if ((ctrl->bRequestType & USB_TYPE_MASK) == USB_TYPE_CLASS) {
  		mtp_log("class request: %d index: %d value: %d length: %d\n",
  			ctrl->bRequest, w_index, w_value, w_length);
  
  		if (ctrl->bRequest == MTP_REQ_CANCEL && w_index == 0
  				&& w_value == 0) {
  			mtp_log("MTP_REQ_CANCEL\n");
  
  			spin_lock_irqsave(&dev->lock, flags);
  			if (dev->state == STATE_BUSY) {
  				dev->state = STATE_CANCELED;
  				wake_up(&dev->read_wq);
  				wake_up(&dev->write_wq);
  			}
  			spin_unlock_irqrestore(&dev->lock, flags);
  
  			/* We need to queue a request to read the remaining
  			 *  bytes, but we don't actually need to look at
  			 * the contents.
  			 */
  			value = w_length;
  		} else if (ctrl->bRequest == MTP_REQ_GET_DEVICE_STATUS
  				&& w_index == 0 && w_value == 0) {
  			struct mtp_device_status *status = cdev->req->buf;
  
  			status->wLength =
  				__constant_cpu_to_le16(sizeof(*status));
  
  			mtp_log("MTP_REQ_GET_DEVICE_STATUS\n");
  			spin_lock_irqsave(&dev->lock, flags);
  			/* device status is "busy" until we report
  			 * the cancelation to userspace
  			 */
  			if (dev->state == STATE_CANCELED)
  				status->wCode =
  					__cpu_to_le16(MTP_RESPONSE_DEVICE_BUSY);
  			else
  				status->wCode =
  					__cpu_to_le16(MTP_RESPONSE_OK);
  			spin_unlock_irqrestore(&dev->lock, flags);
  			value = sizeof(*status);
  		}
  	}
  
  	/* respond with data transfer or status phase? */
  	if (value >= 0) {
  		int rc;
  
  		cdev->req->zero = value < w_length;
  		cdev->req->length = value;
  		rc = usb_ep_queue(cdev->gadget->ep0, cdev->req, GFP_ATOMIC);
  		if (rc < 0)
  			pr_err("%s: response queue error\n", __func__);
  	}
  	return value;
  }
  
  static int
  mtp_function_bind(struct usb_configuration *c, struct usb_function *f)
  {
  	struct usb_composite_dev *cdev = c->cdev;
  	struct mtp_dev	*dev = func_to_mtp(f);
  	int			id;
  	int			ret;
  	struct mtp_instance *fi_mtp;
  
  	dev->cdev = cdev;
  
  	mtp_log("dev: %pK\n", dev);
  	/* ChipIdea controller supports 16K request length for IN endpoint */
  	if (cdev->gadget->is_chipidea && mtp_tx_req_len > 16384) {
  		mtp_log("Truncating Tx Req length to 16K for ChipIdea\n");
  		mtp_tx_req_len = 16384;
  	}
  
  	dev->mtp_rx_req_len = mtp_rx_req_len;
  	dev->mtp_tx_req_len = mtp_tx_req_len;
  	dev->mtp_tx_reqs = mtp_tx_reqs;
  	/* allocate interface ID(s) */
  	id = usb_interface_id(c, f);
  	if (id < 0)
  		return id;
  	mtp_interface_desc.bInterfaceNumber = id;
  
  	if (mtp_string_defs[INTERFACE_STRING_INDEX].id == 0) {
  		ret = usb_string_id(c->cdev);
  		if (ret < 0)
  			return ret;
  		mtp_string_defs[INTERFACE_STRING_INDEX].id = ret;
  		mtp_interface_desc.iInterface = ret;
  	}
  
  	fi_mtp = container_of(f->fi, struct mtp_instance, func_inst);
  
  	if (cdev->use_os_string) {
  		f->os_desc_table = kzalloc(sizeof(*f->os_desc_table),
  					GFP_KERNEL);
  		if (!f->os_desc_table)
  			return -ENOMEM;
  		f->os_desc_n = 1;
  		f->os_desc_table[0].os_desc = &fi_mtp->mtp_os_desc;
  	}
  
  	/* allocate endpoints */
  	ret = mtp_create_bulk_endpoints(dev, &mtp_fullspeed_in_desc,
  			&mtp_fullspeed_out_desc, &mtp_intr_desc);
  	if (ret)
  		return ret;
  
  	/* support high speed hardware */
  	if (gadget_is_dualspeed(c->cdev->gadget)) {
  		mtp_highspeed_in_desc.bEndpointAddress =
  			mtp_fullspeed_in_desc.bEndpointAddress;
  		mtp_highspeed_out_desc.bEndpointAddress =
  			mtp_fullspeed_out_desc.bEndpointAddress;
  	}
  	/* support super speed hardware */
  	if (gadget_is_superspeed(c->cdev->gadget)) {
  		unsigned max_burst;
  
  		/* Calculate bMaxBurst, we know packet size is 1024 */
  		max_burst = min_t(unsigned, MTP_BULK_BUFFER_SIZE / 1024, 15);
  		mtp_ss_in_desc.bEndpointAddress =
  			mtp_fullspeed_in_desc.bEndpointAddress;
  		mtp_ss_in_comp_desc.bMaxBurst = max_burst;
  		mtp_ss_out_desc.bEndpointAddress =
  			mtp_fullspeed_out_desc.bEndpointAddress;
  		mtp_ss_out_comp_desc.bMaxBurst = max_burst;
  	}
  
  	fi_mtp->func_inst.f = &dev->function;
  	mtp_log("%s speed %s: IN/%s, OUT/%s\n",
  		gadget_is_superspeed(c->cdev->gadget) ? "super" :
  		(gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full"),
  		f->name, dev->ep_in->name, dev->ep_out->name);
  	return 0;
  }
  
  static void
  mtp_function_unbind(struct usb_configuration *c, struct usb_function *f)
  {
  	struct mtp_dev	*dev = func_to_mtp(f);
  	struct mtp_instance *fi_mtp;
  	struct usb_request *req;
  	int i;
  	fi_mtp = container_of(f->fi, struct mtp_instance, func_inst);
  	mtp_string_defs[INTERFACE_STRING_INDEX].id = 0;
  	mtp_log("dev: %pK\n", dev);
  	mutex_lock(&dev->read_mutex);
  	while ((req = mtp_req_get(dev, &dev->tx_idle)))
  		mtp_request_free(req, dev->ep_in);
  	for (i = 0; i < RX_REQ_MAX; i++)
  		mtp_request_free(dev->rx_req[i], dev->ep_out);
  	while ((req = mtp_req_get(dev, &dev->intr_idle)))
  		mtp_request_free(req, dev->ep_intr);
  	mutex_unlock(&dev->read_mutex);
  	spin_lock_irq(&dev->lock);
  	dev->state = STATE_OFFLINE;
  	dev->cdev = NULL;
  	spin_unlock_irq(&dev->lock);
  	kfree(f->os_desc_table);
  	f->os_desc_n = 0;
  	fi_mtp->func_inst.f = NULL;
  }
  
  static int mtp_function_set_alt(struct usb_function *f,
  		unsigned intf, unsigned alt)
  {
  	struct mtp_dev	*dev = func_to_mtp(f);
  	struct usb_composite_dev *cdev = f->config->cdev;
  	int ret;
  
  	mtp_log("%d alt: %d\n", intf, alt);
  
  	ret = config_ep_by_speed(cdev->gadget, f, dev->ep_in);
  	if (ret)
  		return ret;
  
  	ret = usb_ep_enable(dev->ep_in);
  	if (ret)
  		return ret;
  
  	ret = config_ep_by_speed(cdev->gadget, f, dev->ep_out);
  	if (ret)
  		return ret;
  
  	ret = usb_ep_enable(dev->ep_out);
  	if (ret) {
  		usb_ep_disable(dev->ep_in);
  		return ret;
  	}
  
  	ret = config_ep_by_speed(cdev->gadget, f, dev->ep_intr);
  	if (ret)
  		return ret;
  
  	ret = usb_ep_enable(dev->ep_intr);
  	if (ret) {
  		usb_ep_disable(dev->ep_out);
  		usb_ep_disable(dev->ep_in);
  		return ret;
  	}
  	dev->state = STATE_READY;
  
  	/* readers may be blocked waiting for us to go online */
  	wake_up(&dev->read_wq);
  	return 0;
  }
  
  static void mtp_function_disable(struct usb_function *f)
  {
  	struct mtp_dev	*dev = func_to_mtp(f);
  
  	mtp_log("\n");
  	spin_lock_irq(&dev->lock);
  	dev->state = STATE_OFFLINE;
  	spin_unlock_irq(&dev->lock);
  	usb_ep_disable(dev->ep_in);
  	usb_ep_disable(dev->ep_out);
  	usb_ep_disable(dev->ep_intr);
  
  	/* readers may be blocked waiting for us to go online */
  	wake_up(&dev->read_wq);
  
  	mtp_log("%s disabled\n", dev->function.name);
  }
  
  static int debug_mtp_read_stats(struct seq_file *s, void *unused)
  {
  	struct mtp_dev *dev = _mtp_dev;
  	int i;
  	unsigned long flags;
  	unsigned int min, max = 0, sum = 0, iteration = 0;
  
  	seq_puts(s, "\n=======================\n");
  	seq_puts(s, "USB MTP OUT related VFS write stats:\n");
  	seq_puts(s, "\n=======================\n");
  	spin_lock_irqsave(&dev->lock, flags);
  	min = dev->perf[0].vfs_wtime;
  	for (i = 0; i < MAX_ITERATION; i++) {
  		seq_printf(s, "vfs write: bytes:%ld\t\t time:%d\n",
  				dev->perf[i].vfs_wbytes,
  				dev->perf[i].vfs_wtime);
  		if (dev->perf[i].vfs_wbytes == dev->mtp_rx_req_len) {
  			sum += dev->perf[i].vfs_wtime;
  			if (min > dev->perf[i].vfs_wtime)
  				min = dev->perf[i].vfs_wtime;
  			if (max < dev->perf[i].vfs_wtime)
  				max = dev->perf[i].vfs_wtime;
  			iteration++;
  		}
  	}
  
  	seq_printf(s, "vfs_write(time in usec) min:%d\t max:%d\t avg:%d\n",
  				min, max, (iteration ? (sum / iteration) : 0));
  	min = max = sum = iteration = 0;
  	seq_puts(s, "\n=======================\n");
  	seq_puts(s, "USB MTP IN related VFS read stats:\n");
  	seq_puts(s, "\n=======================\n");
  
  	min = dev->perf[0].vfs_rtime;
  	for (i = 0; i < MAX_ITERATION; i++) {
  		seq_printf(s, "vfs read: bytes:%ld\t\t time:%d\n",
  				dev->perf[i].vfs_rbytes,
  				dev->perf[i].vfs_rtime);
  		if (dev->perf[i].vfs_rbytes == dev->mtp_tx_req_len) {
  			sum += dev->perf[i].vfs_rtime;
  			if (min > dev->perf[i].vfs_rtime)
  				min = dev->perf[i].vfs_rtime;
  			if (max < dev->perf[i].vfs_rtime)
  				max = dev->perf[i].vfs_rtime;
  			iteration++;
  		}
  	}
  
  	seq_printf(s, "vfs_read(time in usec) min:%d\t max:%d\t avg:%d\n",
  				min, max, (iteration ? (sum / iteration) : 0));
  	spin_unlock_irqrestore(&dev->lock, flags);
  	return 0;
  }
  
  static ssize_t debug_mtp_reset_stats(struct file *file, const char __user *buf,
  				 size_t count, loff_t *ppos)
  {
  	int clear_stats;
  	unsigned long flags;
  	struct mtp_dev *dev = _mtp_dev;
  
  	if (buf == NULL) {
  		pr_err("[%s] EINVAL\n", __func__);
  		goto done;
  	}
  
  	if (kstrtoint(buf, 0, &clear_stats) || clear_stats != 0) {
  		pr_err("Wrong value. To clear stats, enter value as 0.\n");
  		goto done;
  	}
  
  	spin_lock_irqsave(&dev->lock, flags);
  	memset(&dev->perf[0], 0, MAX_ITERATION * sizeof(dev->perf[0]));
  	dev->dbg_read_index = 0;
  	dev->dbg_write_index = 0;
  	spin_unlock_irqrestore(&dev->lock, flags);
  done:
  	return count;
  }
  
  static int debug_mtp_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, debug_mtp_read_stats, inode->i_private);
  }
  
  static const struct file_operations debug_mtp_ops = {
  	.open = debug_mtp_open,
  	.read = seq_read,
  	.write = debug_mtp_reset_stats,
  };
  
  struct dentry *dent_mtp;
  static void mtp_debugfs_init(void)
  {
  	struct dentry *dent_mtp_status;
  
  	dent_mtp = debugfs_create_dir("usb_mtp", 0);
  	if (!dent_mtp || IS_ERR(dent_mtp))
  		return;
  
  	dent_mtp_status = debugfs_create_file("status", 0644, dent_mtp,
  						0, &debug_mtp_ops);
  	if (!dent_mtp_status || IS_ERR(dent_mtp_status)) {
  		debugfs_remove(dent_mtp);
  		dent_mtp = NULL;
  		return;
  	}
  }
  
  static void mtp_debugfs_remove(void)
  {
  	debugfs_remove_recursive(dent_mtp);
  }
  
  static int __mtp_setup(struct mtp_instance *fi_mtp)
  {
  	struct mtp_dev *dev;
  	int ret;
  
  	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
  
  	if (fi_mtp != NULL)
  		fi_mtp->dev = dev;
  
  	if (!dev)
  		return -ENOMEM;
  
  	spin_lock_init(&dev->lock);
  	init_waitqueue_head(&dev->read_wq);
  	init_waitqueue_head(&dev->write_wq);
  	init_waitqueue_head(&dev->intr_wq);
  	atomic_set(&dev->open_excl, 0);
  	atomic_set(&dev->ioctl_excl, 0);
  	INIT_LIST_HEAD(&dev->tx_idle);
  	INIT_LIST_HEAD(&dev->intr_idle);
  
  	dev->wq = create_singlethread_workqueue("f_mtp");
  	if (!dev->wq) {
  		ret = -ENOMEM;
  		goto err1;
  	}
  	INIT_WORK(&dev->send_file_work, send_file_work);
  	INIT_WORK(&dev->receive_file_work, receive_file_work);
  
  	_mtp_dev = dev;
  
  	ret = misc_register(&mtp_device);
  	if (ret)
  		goto err2;
  
  	mtp_debugfs_init();
  	return 0;
  
  err2:
  	destroy_workqueue(dev->wq);
  err1:
  	_mtp_dev = NULL;
  	kfree(dev);
  	printk(KERN_ERR "mtp gadget driver failed to initialize\n");
  	return ret;
  }
  
  static int mtp_setup_configfs(struct mtp_instance *fi_mtp)
  {
  	return __mtp_setup(fi_mtp);
  }
  
  
  static void mtp_cleanup(void)
  {
  	struct mtp_dev *dev = _mtp_dev;
  
  	if (!dev)
  		return;
  
  	mtp_debugfs_remove();
  	misc_deregister(&mtp_device);
  	destroy_workqueue(dev->wq);
  	_mtp_dev = NULL;
  	kfree(dev);
  }
  
  static struct mtp_instance *to_mtp_instance(struct config_item *item)
  {
  	return container_of(to_config_group(item), struct mtp_instance,
  		func_inst.group);
  }
  
  static void mtp_attr_release(struct config_item *item)
  {
  	struct mtp_instance *fi_mtp = to_mtp_instance(item);
  
  	usb_put_function_instance(&fi_mtp->func_inst);
  }
  
  static struct configfs_item_operations mtp_item_ops = {
  	.release        = mtp_attr_release,
  };
  
  static struct config_item_type mtp_func_type = {
  	.ct_item_ops    = &mtp_item_ops,
  	.ct_owner       = THIS_MODULE,
  };
  
  
  static struct mtp_instance *to_fi_mtp(struct usb_function_instance *fi)
  {
  	return container_of(fi, struct mtp_instance, func_inst);
  }
  
  static int mtp_set_inst_name(struct usb_function_instance *fi, const char *name)
  {
  	struct mtp_instance *fi_mtp;
  	char *ptr;
  	int name_len;
  
  	name_len = strlen(name) + 1;
  	if (name_len > MAX_INST_NAME_LEN)
  		return -ENAMETOOLONG;
  
  	ptr = kstrndup(name, name_len, GFP_KERNEL);
  	if (!ptr)
  		return -ENOMEM;
  
  	fi_mtp = to_fi_mtp(fi);
  	fi_mtp->name = ptr;
  
  	return 0;
  }
  
  static void mtp_free_inst(struct usb_function_instance *fi)
  {
  	struct mtp_instance *fi_mtp;
  
  	fi_mtp = to_fi_mtp(fi);
  	kfree(fi_mtp->name);
  	mtp_cleanup();
  	kfree(fi_mtp);
  }
  
  struct usb_function_instance *alloc_inst_mtp_ptp(bool mtp_config)
  {
  	struct mtp_instance *fi_mtp;
  	int ret = 0;
  	struct usb_os_desc *descs[1];
  	char *names[1];
  
  	fi_mtp = kzalloc(sizeof(*fi_mtp), GFP_KERNEL);
  	if (!fi_mtp)
  		return ERR_PTR(-ENOMEM);
  	fi_mtp->func_inst.set_inst_name = mtp_set_inst_name;
  	fi_mtp->func_inst.free_func_inst = mtp_free_inst;
  
  	fi_mtp->mtp_os_desc.ext_compat_id = fi_mtp->mtp_ext_compat_id;
  	INIT_LIST_HEAD(&fi_mtp->mtp_os_desc.ext_prop);
  	descs[0] = &fi_mtp->mtp_os_desc;
  	names[0] = "MTP";
  
  	if (mtp_config) {
  		ret = mtp_setup_configfs(fi_mtp);
  		if (ret) {
  			kfree(fi_mtp);
  			pr_err("Error setting MTP\n");
  			return ERR_PTR(ret);
  		}
  	} else
  		fi_mtp->dev = _mtp_dev;
  
  	config_group_init_type_name(&fi_mtp->func_inst.group,
  					"", &mtp_func_type);
  	usb_os_desc_prepare_interf_dir(&fi_mtp->func_inst.group, 1,
  					descs, names, THIS_MODULE);
  
  	mutex_init(&fi_mtp->dev->read_mutex);
  
  	return  &fi_mtp->func_inst;
  }
  EXPORT_SYMBOL_GPL(alloc_inst_mtp_ptp);
  
  static struct usb_function_instance *mtp_alloc_inst(void)
  {
  		return alloc_inst_mtp_ptp(true);
  }
  
  static int mtp_ctrlreq_configfs(struct usb_function *f,
  				const struct usb_ctrlrequest *ctrl)
  {
  	return mtp_ctrlrequest(f->config->cdev, ctrl);
  }
  
  static void mtp_free(struct usb_function *f)
  {
  	/*NO-OP: no function specific resource allocation in mtp_alloc*/
  }
  
  struct usb_function *function_alloc_mtp_ptp(struct usb_function_instance *fi,
  					bool mtp_config)
  {
  	struct mtp_instance *fi_mtp = to_fi_mtp(fi);
  	struct mtp_dev *dev;
  
  	/*
  	 * PTP piggybacks on MTP function so make sure we have
  	 * created MTP function before we associate this PTP
  	 * function with a gadget configuration.
  	 */
  	if (fi_mtp->dev == NULL) {
  		pr_err("Error: Create MTP function before linking"
  				" PTP function with a gadget configuration\n");
  		pr_err("\t1: Delete existing PTP function if any\n");
  		pr_err("\t2: Create MTP function\n");
  		pr_err("\t3: Create and symlink PTP function"
  				" with a gadget configuration\n");
  		return ERR_PTR(-EINVAL); /* Invalid Configuration */
  	}
  
  	dev = fi_mtp->dev;
  	dev->function.name = DRIVER_NAME;
  	dev->function.strings = mtp_strings;
  	if (mtp_config) {
  		dev->function.fs_descriptors = fs_mtp_descs;
  		dev->function.hs_descriptors = hs_mtp_descs;
  		dev->function.ss_descriptors = ss_mtp_descs;
  	} else {
  		dev->function.fs_descriptors = fs_ptp_descs;
  		dev->function.hs_descriptors = hs_ptp_descs;
  		dev->function.ss_descriptors = ss_ptp_descs;
  	}
  	dev->function.bind = mtp_function_bind;
  	dev->function.unbind = mtp_function_unbind;
  	dev->function.set_alt = mtp_function_set_alt;
  	dev->function.disable = mtp_function_disable;
  	dev->function.setup = mtp_ctrlreq_configfs;
  	dev->function.free_func = mtp_free;
  
  	return &dev->function;
  }
  EXPORT_SYMBOL_GPL(function_alloc_mtp_ptp);
  
  static struct usb_function *mtp_alloc(struct usb_function_instance *fi)
  {
  	return function_alloc_mtp_ptp(fi, true);
  }
  
  DECLARE_USB_FUNCTION(mtp, mtp_alloc_inst, mtp_alloc);
  
  static int mtp_init(void)
  {
  	_mtp_ipc_log = ipc_log_context_create(NUM_PAGES, "usb_mtp", 0);
  	if (IS_ERR_OR_NULL(_mtp_ipc_log))
  		_mtp_ipc_log =  NULL;
  
  	return usb_function_register(&mtpusb_func);
  }
  module_init(mtp_init);
  
  static void __exit mtp_exit(void)
  {
  	ipc_log_context_destroy(_mtp_ipc_log);
  	usb_function_unregister(&mtpusb_func);
  }
  module_exit(mtp_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("MTP function driver");
  