text: /*
   * hdm_usb.c - Hardware dependent module for USB
   *
   * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
   *
   * 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.
   *
   * This file is licensed under GPLv2.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  #include <linux/module.h>
  #include <linux/fs.h>
  #include <linux/usb.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <linux/cdev.h>
  #include <linux/device.h>
  #include <linux/list.h>
  #include <linux/completion.h>
  #include <linux/mutex.h>
  #include <linux/spinlock.h>
  #include <linux/interrupt.h>
  #include <linux/workqueue.h>
  #include <linux/sysfs.h>
  #include <linux/dma-mapping.h>
  #include <linux/etherdevice.h>
  #include <linux/uaccess.h>
  #include "mostcore.h"
  
  #define USB_MTU			512
  #define NO_ISOCHRONOUS_URB	0
  #define AV_PACKETS_PER_XACT	2
  #define BUF_CHAIN_SIZE		0xFFFF
  #define MAX_NUM_ENDPOINTS	30
  #define MAX_SUFFIX_LEN		10
  #define MAX_STRING_LEN		80
  #define MAX_BUF_SIZE		0xFFFF
  
  #define USB_VENDOR_ID_SMSC	0x0424  /* VID: SMSC */
  #define USB_DEV_ID_BRDG		0xC001  /* PID: USB Bridge */
  #define USB_DEV_ID_OS81118	0xCF18  /* PID: USB OS81118 */
  #define USB_DEV_ID_OS81119	0xCF19  /* PID: USB OS81119 */
  #define USB_DEV_ID_OS81210	0xCF30  /* PID: USB OS81210 */
  /* DRCI Addresses */
  #define DRCI_REG_NI_STATE	0x0100
  #define DRCI_REG_PACKET_BW	0x0101
  #define DRCI_REG_NODE_ADDR	0x0102
  #define DRCI_REG_NODE_POS	0x0103
  #define DRCI_REG_MEP_FILTER	0x0140
  #define DRCI_REG_HASH_TBL0	0x0141
  #define DRCI_REG_HASH_TBL1	0x0142
  #define DRCI_REG_HASH_TBL2	0x0143
  #define DRCI_REG_HASH_TBL3	0x0144
  #define DRCI_REG_HW_ADDR_HI	0x0145
  #define DRCI_REG_HW_ADDR_MI	0x0146
  #define DRCI_REG_HW_ADDR_LO	0x0147
  #define DRCI_REG_BASE		0x1100
  #define DRCI_COMMAND		0x02
  #define DRCI_READ_REQ		0xA0
  #define DRCI_WRITE_REQ		0xA1
  
  /**
   * struct most_dci_obj - Direct Communication Interface
   * @kobj:position in sysfs
   * @usb_device: pointer to the usb device
   * @reg_addr: register address for arbitrary DCI access
   */
  struct most_dci_obj {
  	struct kobject kobj;
  	struct usb_device *usb_device;
  	u16 reg_addr;
  };
  
  #define to_dci_obj(p) container_of(p, struct most_dci_obj, kobj)
  
  struct most_dev;
  
  struct clear_hold_work {
  	struct work_struct ws;
  	struct most_dev *mdev;
  	unsigned int channel;
  	int pipe;
  };
  
  #define to_clear_hold_work(w) container_of(w, struct clear_hold_work, ws)
  
  /**
   * struct most_dev - holds all usb interface specific stuff
   * @parent: parent object in sysfs
   * @usb_device: pointer to usb device
   * @iface: hardware interface
   * @cap: channel capabilities
   * @conf: channel configuration
   * @dci: direct communication interface of hardware
   * @ep_address: endpoint address table
   * @description: device description
   * @suffix: suffix for channel name
   * @channel_lock: synchronize channel access
   * @padding_active: indicates channel uses padding
   * @is_channel_healthy: health status table of each channel
   * @busy_urbs: list of anchored items
   * @io_mutex: synchronize I/O with disconnect
   * @link_stat_timer: timer for link status reports
   * @poll_work_obj: work for polling link status
   */
  struct most_dev {
  	struct kobject *parent;
  	struct usb_device *usb_device;
  	struct most_interface iface;
  	struct most_channel_capability *cap;
  	struct most_channel_config *conf;
  	struct most_dci_obj *dci;
  	u8 *ep_address;
  	char description[MAX_STRING_LEN];
  	char suffix[MAX_NUM_ENDPOINTS][MAX_SUFFIX_LEN];
  	spinlock_t channel_lock[MAX_NUM_ENDPOINTS]; /* sync channel access */
  	bool padding_active[MAX_NUM_ENDPOINTS];
  	bool is_channel_healthy[MAX_NUM_ENDPOINTS];
  	struct clear_hold_work clear_work[MAX_NUM_ENDPOINTS];
  	struct usb_anchor *busy_urbs;
  	struct mutex io_mutex;
  	struct timer_list link_stat_timer;
  	struct work_struct poll_work_obj;
  	void (*on_netinfo)(struct most_interface *, unsigned char,
  			   unsigned char *);
  };
  
  #define to_mdev(d) container_of(d, struct most_dev, iface)
  #define to_mdev_from_work(w) container_of(w, struct most_dev, poll_work_obj)
  
  static void wq_clear_halt(struct work_struct *wq_obj);
  static void wq_netinfo(struct work_struct *wq_obj);
  
  /**
   * drci_rd_reg - read a DCI register
   * @dev: usb device
   * @reg: register address
   * @buf: buffer to store data
   *
   * This is reads data from INIC's direct register communication interface
   */
  static inline int drci_rd_reg(struct usb_device *dev, u16 reg, u16 *buf)
  {
  	int retval;
  	__le16 *dma_buf = kzalloc(sizeof(*dma_buf), GFP_KERNEL);
  	u8 req_type = USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE;
  
  	if (!dma_buf)
  		return -ENOMEM;
  
  	retval = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
  				 DRCI_READ_REQ, req_type,
  				 0x0000,
  				 reg, dma_buf, sizeof(*dma_buf), 5 * HZ);
  	*buf = le16_to_cpu(*dma_buf);
  	kfree(dma_buf);
  
  	return retval;
  }
  
  /**
   * drci_wr_reg - write a DCI register
   * @dev: usb device
   * @reg: register address
   * @data: data to write
   *
   * This is writes data to INIC's direct register communication interface
   */
  static inline int drci_wr_reg(struct usb_device *dev, u16 reg, u16 data)
  {
  	return usb_control_msg(dev,
  			       usb_sndctrlpipe(dev, 0),
  			       DRCI_WRITE_REQ,
  			       USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
  			       data,
  			       reg,
  			       NULL,
  			       0,
  			       5 * HZ);
  }
  
  static inline int start_sync_ep(struct usb_device *usb_dev, u16 ep)
  {
  	return drci_wr_reg(usb_dev, DRCI_REG_BASE + DRCI_COMMAND + ep * 16, 1);
  }
  
  /**
   * get_stream_frame_size - calculate frame size of current configuration
   * @cfg: channel configuration
   */
  static unsigned int get_stream_frame_size(struct most_channel_config *cfg)
  {
  	unsigned int frame_size = 0;
  	unsigned int sub_size = cfg->subbuffer_size;
  
  	if (!sub_size) {
  		pr_warn("Misconfig: Subbuffer size zero.\n");
  		return frame_size;
  	}
  	switch (cfg->data_type) {
  	case MOST_CH_ISOC:
  		frame_size = AV_PACKETS_PER_XACT * sub_size;
  		break;
  	case MOST_CH_SYNC:
  		if (cfg->packets_per_xact == 0) {
  			pr_warn("Misconfig: Packets per XACT zero\n");
  			frame_size = 0;
  		} else if (cfg->packets_per_xact == 0xFF) {
  			frame_size = (USB_MTU / sub_size) * sub_size;
  		} else {
  			frame_size = cfg->packets_per_xact * sub_size;
  		}
  		break;
  	default:
  		pr_warn("Query frame size of non-streaming channel\n");
  		break;
  	}
  	return frame_size;
  }
  
  /**
   * hdm_poison_channel - mark buffers of this channel as invalid
   * @iface: pointer to the interface
   * @channel: channel ID
   *
   * This unlinks all URBs submitted to the HCD,
   * calls the associated completion function of the core and removes
   * them from the list.
   *
   * Returns 0 on success or error code otherwise.
   */
  static int hdm_poison_channel(struct most_interface *iface, int channel)
  {
  	struct most_dev *mdev = to_mdev(iface);
  	unsigned long flags;
  	spinlock_t *lock; /* temp. lock */
  
  	if (unlikely(!iface)) {
  		dev_warn(&mdev->usb_device->dev, "Poison: Bad interface.\n");
  		return -EIO;
  	}
  	if (unlikely(channel < 0 || channel >= iface->num_channels)) {
  		dev_warn(&mdev->usb_device->dev, "Channel ID out of range.\n");
  		return -ECHRNG;
  	}
  
  	lock = mdev->channel_lock + channel;
  	spin_lock_irqsave(lock, flags);
  	mdev->is_channel_healthy[channel] = false;
  	spin_unlock_irqrestore(lock, flags);
  
  	cancel_work_sync(&mdev->clear_work[channel].ws);
  
  	mutex_lock(&mdev->io_mutex);
  	usb_kill_anchored_urbs(&mdev->busy_urbs[channel]);
  	if (mdev->padding_active[channel])
  		mdev->padding_active[channel] = false;
  
  	if (mdev->conf[channel].data_type == MOST_CH_ASYNC) {
  		del_timer_sync(&mdev->link_stat_timer);
  		cancel_work_sync(&mdev->poll_work_obj);
  	}
  	mutex_unlock(&mdev->io_mutex);
  	return 0;
  }
  
  /**
   * hdm_add_padding - add padding bytes
   * @mdev: most device
   * @channel: channel ID
   * @mbo: buffer object
   *
   * This inserts the INIC hardware specific padding bytes into a streaming
   * channel's buffer
   */
  static int hdm_add_padding(struct most_dev *mdev, int channel, struct mbo *mbo)
  {
  	struct most_channel_config *conf = &mdev->conf[channel];
  	unsigned int frame_size = get_stream_frame_size(conf);
  	unsigned int j, num_frames;
  
  	if (!frame_size)
  		return -EIO;
  	num_frames = mbo->buffer_length / frame_size;
  
  	if (num_frames < 1) {
  		dev_err(&mdev->usb_device->dev,
  			"Missed minimal transfer unit.\n");
  		return -EIO;
  	}
  
  	for (j = num_frames - 1; j > 0; j--)
  		memmove(mbo->virt_address + j * USB_MTU,
  			mbo->virt_address + j * frame_size,
  			frame_size);
  	mbo->buffer_length = num_frames * USB_MTU;
  	return 0;
  }
  
  /**
   * hdm_remove_padding - remove padding bytes
   * @mdev: most device
   * @channel: channel ID
   * @mbo: buffer object
   *
   * This takes the INIC hardware specific padding bytes off a streaming
   * channel's buffer.
   */
  static int hdm_remove_padding(struct most_dev *mdev, int channel,
  			      struct mbo *mbo)
  {
  	struct most_channel_config *const conf = &mdev->conf[channel];
  	unsigned int frame_size = get_stream_frame_size(conf);
  	unsigned int j, num_frames;
  
  	if (!frame_size)
  		return -EIO;
  	num_frames = mbo->processed_length / USB_MTU;
  
  	for (j = 1; j < num_frames; j++)
  		memmove(mbo->virt_address + frame_size * j,
  			mbo->virt_address + USB_MTU * j,
  			frame_size);
  
  	mbo->processed_length = frame_size * num_frames;
  	return 0;
  }
  
  /**
   * hdm_write_completion - completion function for submitted Tx URBs
   * @urb: the URB that has been completed
   *
   * This checks the status of the completed URB. In case the URB has been
   * unlinked before, it is immediately freed. On any other error the MBO
   * transfer flag is set. On success it frees allocated resources and calls
   * the completion function.
   *
   * Context: interrupt!
   */
  static void hdm_write_completion(struct urb *urb)
  {
  	struct mbo *mbo = urb->context;
  	struct most_dev *mdev = to_mdev(mbo->ifp);
  	unsigned int channel = mbo->hdm_channel_id;
  	struct device *dev = &mdev->usb_device->dev;
  	spinlock_t *lock = mdev->channel_lock + channel;
  	unsigned long flags;
  
  	spin_lock_irqsave(lock, flags);
  
  	mbo->processed_length = 0;
  	mbo->status = MBO_E_INVAL;
  	if (likely(mdev->is_channel_healthy[channel])) {
  		switch (urb->status) {
  		case 0:
  		case -ESHUTDOWN:
  			mbo->processed_length = urb->actual_length;
  			mbo->status = MBO_SUCCESS;
  			break;
  		case -EPIPE:
  			dev_warn(dev, "Broken OUT pipe detected\n");
  			mdev->is_channel_healthy[channel] = false;
  			mdev->clear_work[channel].pipe = urb->pipe;
  			schedule_work(&mdev->clear_work[channel].ws);
  			break;
  		case -ENODEV:
  		case -EPROTO:
  			mbo->status = MBO_E_CLOSE;
  			break;
  		}
  	}
  
  	spin_unlock_irqrestore(lock, flags);
  
  	if (likely(mbo->complete))
  		mbo->complete(mbo);
  	usb_free_urb(urb);
  }
  
  /**
   * hdm_read_completion - completion function for submitted Rx URBs
   * @urb: the URB that has been completed
   *
   * This checks the status of the completed URB. In case the URB has been
   * unlinked before it is immediately freed. On any other error the MBO transfer
   * flag is set. On success it frees allocated resources, removes
   * padding bytes -if necessary- and calls the completion function.
   *
   * Context: interrupt!
   *
   * **************************************************************************
   *                   Error codes returned by in urb->status
   *                   or in iso_frame_desc[n].status (for ISO)
   * *************************************************************************
   *
   * USB device drivers may only test urb status values in completion handlers.
   * This is because otherwise there would be a race between HCDs updating
   * these values on one CPU, and device drivers testing them on another CPU.
   *
   * A transfer's actual_length may be positive even when an error has been
   * reported.  That's because transfers often involve several packets, so that
   * one or more packets could finish before an error stops further endpoint I/O.
   *
   * For isochronous URBs, the urb status value is non-zero only if the URB is
   * unlinked, the device is removed, the host controller is disabled or the total
   * transferred length is less than the requested length and the URB_SHORT_NOT_OK
   * flag is set.  Completion handlers for isochronous URBs should only see
   * urb->status set to zero, -ENOENT, -ECONNRESET, -ESHUTDOWN, or -EREMOTEIO.
   * Individual frame descriptor status fields may report more status codes.
   *
   *
   * 0			Transfer completed successfully
   *
   * -ENOENT		URB was synchronously unlinked by usb_unlink_urb
   *
   * -EINPROGRESS		URB still pending, no results yet
   *			(That is, if drivers see this it's a bug.)
   *
   * -EPROTO (*, **)	a) bitstuff error
   *			b) no response packet received within the
   *			   prescribed bus turn-around time
   *			c) unknown USB error
   *
   * -EILSEQ (*, **)	a) CRC mismatch
   *			b) no response packet received within the
   *			   prescribed bus turn-around time
   *			c) unknown USB error
   *
   *			Note that often the controller hardware does not
   *			distinguish among cases a), b), and c), so a
   *			driver cannot tell whether there was a protocol
   *			error, a failure to respond (often caused by
   *			device disconnect), or some other fault.
   *
   * -ETIME (**)		No response packet received within the prescribed
   *			bus turn-around time.  This error may instead be
   *			reported as -EPROTO or -EILSEQ.
   *
   * -ETIMEDOUT		Synchronous USB message functions use this code
   *			to indicate timeout expired before the transfer
   *			completed, and no other error was reported by HC.
   *
   * -EPIPE (**)		Endpoint stalled.  For non-control endpoints,
   *			reset this status with usb_clear_halt().
   *
   * -ECOMM		During an IN transfer, the host controller
   *			received data from an endpoint faster than it
   *			could be written to system memory
   *
   * -ENOSR		During an OUT transfer, the host controller
   *			could not retrieve data from system memory fast
   *			enough to keep up with the USB data rate
   *
   * -EOVERFLOW (*)	The amount of data returned by the endpoint was
   *			greater than either the max packet size of the
   *			endpoint or the remaining buffer size.  "Babble".
   *
   * -EREMOTEIO		The data read from the endpoint did not fill the
   *			specified buffer, and URB_SHORT_NOT_OK was set in
   *			urb->transfer_flags.
   *
   * -ENODEV		Device was removed.  Often preceded by a burst of
   *			other errors, since the hub driver doesn't detect
   *			device removal events immediately.
   *
   * -EXDEV		ISO transfer only partially completed
   *			(only set in iso_frame_desc[n].status, not urb->status)
   *
   * -EINVAL		ISO madness, if this happens: Log off and go home
   *
   * -ECONNRESET		URB was asynchronously unlinked by usb_unlink_urb
   *
   * -ESHUTDOWN		The device or host controller has been disabled due
   *			to some problem that could not be worked around,
   *			such as a physical disconnect.
   *
   *
   * (*) Error codes like -EPROTO, -EILSEQ and -EOVERFLOW normally indicate
   * hardware problems such as bad devices (including firmware) or cables.
   *
   * (**) This is also one of several codes that different kinds of host
   * controller use to indicate a transfer has failed because of device
   * disconnect.  In the interval before the hub driver starts disconnect
   * processing, devices may receive such fault reports for every request.
   *
   * See <https://www.kernel.org/doc/Documentation/driver-api/usb/error-codes.rst>
   */
  static void hdm_read_completion(struct urb *urb)
  {
  	struct mbo *mbo = urb->context;
  	struct most_dev *mdev = to_mdev(mbo->ifp);
  	unsigned int channel = mbo->hdm_channel_id;
  	struct device *dev = &mdev->usb_device->dev;
  	spinlock_t *lock = mdev->channel_lock + channel;
  	unsigned long flags;
  
  	spin_lock_irqsave(lock, flags);
  
  	mbo->processed_length = 0;
  	mbo->status = MBO_E_INVAL;
  	if (likely(mdev->is_channel_healthy[channel])) {
  		switch (urb->status) {
  		case 0:
  		case -ESHUTDOWN:
  			mbo->processed_length = urb->actual_length;
  			mbo->status = MBO_SUCCESS;
  			if (mdev->padding_active[channel] &&
  			    hdm_remove_padding(mdev, channel, mbo)) {
  				mbo->processed_length = 0;
  				mbo->status = MBO_E_INVAL;
  			}
  			break;
  		case -EPIPE:
  			dev_warn(dev, "Broken IN pipe detected\n");
  			mdev->is_channel_healthy[channel] = false;
  			mdev->clear_work[channel].pipe = urb->pipe;
  			schedule_work(&mdev->clear_work[channel].ws);
  			break;
  		case -ENODEV:
  		case -EPROTO:
  			mbo->status = MBO_E_CLOSE;
  			break;
  		case -EOVERFLOW:
  			dev_warn(dev, "Babble on IN pipe detected\n");
  			break;
  		}
  	}
  
  	spin_unlock_irqrestore(lock, flags);
  
  	if (likely(mbo->complete))
  		mbo->complete(mbo);
  	usb_free_urb(urb);
  }
  
  /**
   * hdm_enqueue - receive a buffer to be used for data transfer
   * @iface: interface to enqueue to
   * @channel: ID of the channel
   * @mbo: pointer to the buffer object
   *
   * This allocates a new URB and fills it according to the channel
   * that is being used for transmission of data. Before the URB is
   * submitted it is stored in the private anchor list.
   *
   * Returns 0 on success. On any error the URB is freed and a error code
   * is returned.
   *
   * Context: Could in _some_ cases be interrupt!
   */
  static int hdm_enqueue(struct most_interface *iface, int channel,
  		       struct mbo *mbo)
  {
  	struct most_dev *mdev;
  	struct most_channel_config *conf;
  	struct device *dev;
  	int retval = 0;
  	struct urb *urb;
  	unsigned long length;
  	void *virt_address;
  
  	if (unlikely(!iface || !mbo))
  		return -EIO;
  	if (unlikely(iface->num_channels <= channel || channel < 0))
  		return -ECHRNG;
  
  	mdev = to_mdev(iface);
  	conf = &mdev->conf[channel];
  	dev = &mdev->usb_device->dev;
  
  	if (!mdev->usb_device)
  		return -ENODEV;
  
  	urb = usb_alloc_urb(NO_ISOCHRONOUS_URB, GFP_ATOMIC);
  	if (!urb)
  		return -ENOMEM;
  
  	if ((conf->direction & MOST_CH_TX) && mdev->padding_active[channel] &&
  	    hdm_add_padding(mdev, channel, mbo)) {
  		retval = -EIO;
  		goto _error;
  	}
  
  	urb->transfer_dma = mbo->bus_address;
  	virt_address = mbo->virt_address;
  	length = mbo->buffer_length;
  
  	if (conf->direction & MOST_CH_TX) {
  		usb_fill_bulk_urb(urb, mdev->usb_device,
  				  usb_sndbulkpipe(mdev->usb_device,
  						  mdev->ep_address[channel]),
  				  virt_address,
  				  length,
  				  hdm_write_completion,
  				  mbo);
  		if (conf->data_type != MOST_CH_ISOC)
  			urb->transfer_flags |= URB_ZERO_PACKET;
  	} else {
  		usb_fill_bulk_urb(urb, mdev->usb_device,
  				  usb_rcvbulkpipe(mdev->usb_device,
  						  mdev->ep_address[channel]),
  				  virt_address,
  				  length + conf->extra_len,
  				  hdm_read_completion,
  				  mbo);
  	}
  	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
  
  	usb_anchor_urb(urb, &mdev->busy_urbs[channel]);
  
  	retval = usb_submit_urb(urb, GFP_KERNEL);
  	if (retval) {
  		dev_err(dev, "URB submit failed with error %d.\n", retval);
  		goto _error_1;
  	}
  	return 0;
  
  _error_1:
  	usb_unanchor_urb(urb);
  _error:
  	usb_free_urb(urb);
  	return retval;
  }
  
  /**
   * hdm_configure_channel - receive channel configuration from core
   * @iface: interface
   * @channel: channel ID
   * @conf: structure that holds the configuration information
   *
   * The attached network interface controller (NIC) supports a padding mode
   * to avoid short packets on USB, hence increasing the performance due to a
   * lower interrupt load. This mode is default for synchronous data and can
   * be switched on for isochronous data. In case padding is active the
   * driver needs to know the frame size of the payload in order to calculate
   * the number of bytes it needs to pad when transmitting or to cut off when
   * receiving data.
   *
   */
  static int hdm_configure_channel(struct most_interface *iface, int channel,
  				 struct most_channel_config *conf)
  {
  	unsigned int num_frames;
  	unsigned int frame_size;
  	struct most_dev *mdev = to_mdev(iface);
  	struct device *dev = &mdev->usb_device->dev;
  
  	mdev->is_channel_healthy[channel] = true;
  	mdev->clear_work[channel].channel = channel;
  	mdev->clear_work[channel].mdev = mdev;
  	INIT_WORK(&mdev->clear_work[channel].ws, wq_clear_halt);
  
  	if (unlikely(!iface || !conf)) {
  		dev_err(dev, "Bad interface or config pointer.\n");
  		return -EINVAL;
  	}
  	if (unlikely(channel < 0 || channel >= iface->num_channels)) {
  		dev_err(dev, "Channel ID out of range.\n");
  		return -EINVAL;
  	}
  	if (!conf->num_buffers || !conf->buffer_size) {
  		dev_err(dev, "Misconfig: buffer size or #buffers zero.\n");
  		return -EINVAL;
  	}
  
  	if (conf->data_type != MOST_CH_SYNC &&
  	    !(conf->data_type == MOST_CH_ISOC &&
  	      conf->packets_per_xact != 0xFF)) {
  		mdev->padding_active[channel] = false;
  		/*
  		 * Since the NIC's padding mode is not going to be
  		 * used, we can skip the frame size calculations and
  		 * move directly on to exit.
  		 */
  		goto exit;
  	}
  
  	mdev->padding_active[channel] = true;
  
  	frame_size = get_stream_frame_size(conf);
  	if (frame_size == 0 || frame_size > USB_MTU) {
  		dev_warn(dev, "Misconfig: frame size wrong\n");
  		return -EINVAL;
  	}
  
  	num_frames = conf->buffer_size / frame_size;
  
  	if (conf->buffer_size % frame_size) {
  		u16 old_size = conf->buffer_size;
  
  		conf->buffer_size = num_frames * frame_size;
  		dev_warn(dev, "%s: fixed buffer size (%d -> %d)\n",
  			 mdev->suffix[channel], old_size, conf->buffer_size);
  	}
  
  	/* calculate extra length to comply w/ HW padding */
  	conf->extra_len = num_frames * (USB_MTU - frame_size);
  
  exit:
  	mdev->conf[channel] = *conf;
  	if (conf->data_type == MOST_CH_ASYNC) {
  		u16 ep = mdev->ep_address[channel];
  
  		if (start_sync_ep(mdev->usb_device, ep) < 0)
  			dev_warn(dev, "sync for ep%02x failed", ep);
  	}
  	return 0;
  }
  
  /**
   * hdm_request_netinfo - request network information
   * @iface: pointer to interface
   * @channel: channel ID
   *
   * This is used as trigger to set up the link status timer that
   * polls for the NI state of the INIC every 2 seconds.
   *
   */
  static void hdm_request_netinfo(struct most_interface *iface, int channel,
  				void (*on_netinfo)(struct most_interface *,
  						   unsigned char,
  						   unsigned char *))
  {
  	struct most_dev *mdev;
  
  	BUG_ON(!iface);
  	mdev = to_mdev(iface);
  	mdev->on_netinfo = on_netinfo;
  	if (!on_netinfo)
  		return;
  
  	mdev->link_stat_timer.expires = jiffies + HZ;
  	mod_timer(&mdev->link_stat_timer, mdev->link_stat_timer.expires);
  }
  
  /**
   * link_stat_timer_handler - schedule work obtaining mac address and link status
   * @data: pointer to USB device instance
   *
   * The handler runs in interrupt context. That's why we need to defer the
   * tasks to a work queue.
   */
  static void link_stat_timer_handler(struct timer_list *t)
  {
  	struct most_dev *mdev = from_timer(mdev, t, link_stat_timer);
  
  	schedule_work(&mdev->poll_work_obj);
  	mdev->link_stat_timer.expires = jiffies + (2 * HZ);
  	add_timer(&mdev->link_stat_timer);
  }
  
  /**
   * wq_netinfo - work queue function to deliver latest networking information
   * @wq_obj: object that holds data for our deferred work to do
   *
   * This retrieves the network interface status of the USB INIC
   */
  static void wq_netinfo(struct work_struct *wq_obj)
  {
  	struct most_dev *mdev = to_mdev_from_work(wq_obj);
  	struct usb_device *usb_device = mdev->usb_device;
  	struct device *dev = &usb_device->dev;
  	u16 hi, mi, lo, link;
  	u8 hw_addr[6];
  
  	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_HI, &hi) < 0) {
  		dev_err(dev, "Vendor request 'hw_addr_hi' failed\n");
  		return;
  	}
  
  	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_MI, &mi) < 0) {
  		dev_err(dev, "Vendor request 'hw_addr_mid' failed\n");
  		return;
  	}
  
  	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_LO, &lo) < 0) {
  		dev_err(dev, "Vendor request 'hw_addr_low' failed\n");
  		return;
  	}
  
  	if (drci_rd_reg(usb_device, DRCI_REG_NI_STATE, &link) < 0) {
  		dev_err(dev, "Vendor request 'link status' failed\n");
  		return;
  	}
  
  	hw_addr[0] = hi >> 8;
  	hw_addr[1] = hi;
  	hw_addr[2] = mi >> 8;
  	hw_addr[3] = mi;
  	hw_addr[4] = lo >> 8;
  	hw_addr[5] = lo;
  
  	if (mdev->on_netinfo)
  		mdev->on_netinfo(&mdev->iface, link, hw_addr);
  }
  
  /**
   * wq_clear_halt - work queue function
   * @wq_obj: work_struct object to execute
   *
   * This sends a clear_halt to the given USB pipe.
   */
  static void wq_clear_halt(struct work_struct *wq_obj)
  {
  	struct clear_hold_work *clear_work = to_clear_hold_work(wq_obj);
  	struct most_dev *mdev = clear_work->mdev;
  	unsigned int channel = clear_work->channel;
  	int pipe = clear_work->pipe;
  
  	mutex_lock(&mdev->io_mutex);
  	most_stop_enqueue(&mdev->iface, channel);
  	usb_kill_anchored_urbs(&mdev->busy_urbs[channel]);
  	if (usb_clear_halt(mdev->usb_device, pipe))
  		dev_warn(&mdev->usb_device->dev, "Failed to reset endpoint.\n");
  
  	mdev->is_channel_healthy[channel] = true;
  	most_resume_enqueue(&mdev->iface, channel);
  	mutex_unlock(&mdev->io_mutex);
  }
  
  /**
   * hdm_usb_fops - file operation table for USB driver
   */
  static const struct file_operations hdm_usb_fops = {
  	.owner = THIS_MODULE,
  };
  
  /**
   * usb_device_id - ID table for HCD device probing
   */
  static const struct usb_device_id usbid[] = {
  	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_BRDG), },
  	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81118), },
  	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81119), },
  	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81210), },
  	{ } /* Terminating entry */
  };
  
  #define MOST_DCI_RO_ATTR(_name) \
  	struct most_dci_attribute most_dci_attr_##_name = \
  		__ATTR(_name, 0444, show_value, NULL)
  
  #define MOST_DCI_ATTR(_name) \
  	struct most_dci_attribute most_dci_attr_##_name = \
  		__ATTR(_name, 0644, show_value, store_value)
  
  #define MOST_DCI_WO_ATTR(_name) \
  	struct most_dci_attribute most_dci_attr_##_name = \
  		__ATTR(_name, 0200, NULL, store_value)
  
  /**
   * struct most_dci_attribute - to access the attributes of a dci object
   * @attr: attributes of a dci object
   * @show: pointer to the show function
   * @store: pointer to the store function
   */
  struct most_dci_attribute {
  	struct attribute attr;
  	ssize_t (*show)(struct most_dci_obj *d,
  			struct most_dci_attribute *attr,
  			char *buf);
  	ssize_t (*store)(struct most_dci_obj *d,
  			 struct most_dci_attribute *attr,
  			 const char *buf,
  			 size_t count);
  };
  
  #define to_dci_attr(a) container_of(a, struct most_dci_attribute, attr)
  
  /**
   * dci_attr_show - show function for dci object
   * @kobj: pointer to kobject
   * @attr: pointer to attribute struct
   * @buf: buffer
   */
  static ssize_t dci_attr_show(struct kobject *kobj, struct attribute *attr,
  			     char *buf)
  {
  	struct most_dci_attribute *dci_attr = to_dci_attr(attr);
  	struct most_dci_obj *dci_obj = to_dci_obj(kobj);
  
  	if (!dci_attr->show)
  		return -EIO;
  
  	return dci_attr->show(dci_obj, dci_attr, buf);
  }
  
  /**
   * dci_attr_store - store function for dci object
   * @kobj: pointer to kobject
   * @attr: pointer to attribute struct
   * @buf: buffer
   * @len: length of buffer
   */
  static ssize_t dci_attr_store(struct kobject *kobj,
  			      struct attribute *attr,
  			      const char *buf,
  			      size_t len)
  {
  	struct most_dci_attribute *dci_attr = to_dci_attr(attr);
  	struct most_dci_obj *dci_obj = to_dci_obj(kobj);
  
  	if (!dci_attr->store)
  		return -EIO;
  
  	return dci_attr->store(dci_obj, dci_attr, buf, len);
  }
  
  static const struct sysfs_ops most_dci_sysfs_ops = {
  	.show = dci_attr_show,
  	.store = dci_attr_store,
  };
  
  /**
   * most_dci_release - release function for dci object
   * @kobj: pointer to kobject
   *
   * This frees the memory allocated for the dci object
   */
  static void most_dci_release(struct kobject *kobj)
  {
  	struct most_dci_obj *dci_obj = to_dci_obj(kobj);
  
  	kfree(dci_obj);
  }
  
  struct regs {
  	const char *name;
  	u16 reg;
  };
  
  static const struct regs ro_regs[] = {
  	{ "ni_state", DRCI_REG_NI_STATE },
  	{ "packet_bandwidth", DRCI_REG_PACKET_BW },
  	{ "node_address", DRCI_REG_NODE_ADDR },
  	{ "node_position", DRCI_REG_NODE_POS },
  };
  
  static const struct regs rw_regs[] = {
  	{ "mep_filter", DRCI_REG_MEP_FILTER },
  	{ "mep_hash0", DRCI_REG_HASH_TBL0 },
  	{ "mep_hash1", DRCI_REG_HASH_TBL1 },
  	{ "mep_hash2", DRCI_REG_HASH_TBL2 },
  	{ "mep_hash3", DRCI_REG_HASH_TBL3 },
  	{ "mep_eui48_hi", DRCI_REG_HW_ADDR_HI },
  	{ "mep_eui48_mi", DRCI_REG_HW_ADDR_MI },
  	{ "mep_eui48_lo", DRCI_REG_HW_ADDR_LO },
  };
  
  static int get_stat_reg_addr(const struct regs *regs, int size,
  			     const char *name, u16 *reg_addr)
  {
  	int i;
  
  	for (i = 0; i < size; i++) {
  		if (!strcmp(name, regs[i].name)) {
  			*reg_addr = regs[i].reg;
  			return 0;
  		}
  	}
  	return -EFAULT;
  }
  
  #define get_static_reg_addr(regs, name, reg_addr) \
  	get_stat_reg_addr(regs, ARRAY_SIZE(regs), name, reg_addr)
  
  static ssize_t show_value(struct most_dci_obj *dci_obj,
  			  struct most_dci_attribute *attr, char *buf)
  {
  	const char *name = attr->attr.name;
  	u16 val;
  	u16 reg_addr;
  	int err;
  
  	if (!strcmp(name, "arb_address"))
  		return snprintf(buf, PAGE_SIZE, "%04x\n", dci_obj->reg_addr);
  
  	if (!strcmp(name, "arb_value"))
  		reg_addr = dci_obj->reg_addr;
  	else if (get_static_reg_addr(ro_regs, name, &reg_addr) &&
  		 get_static_reg_addr(rw_regs, name, &reg_addr))
  		return -EFAULT;
  
  	err = drci_rd_reg(dci_obj->usb_device, reg_addr, &val);
  	if (err < 0)
  		return err;
  
  	return snprintf(buf, PAGE_SIZE, "%04x\n", val);
  }
  
  static ssize_t store_value(struct most_dci_obj *dci_obj,
  			   struct most_dci_attribute *attr,
  			   const char *buf, size_t count)
  {
  	u16 val;
  	u16 reg_addr;
  	const char *name = attr->attr.name;
  	struct usb_device *usb_dev = dci_obj->usb_device;
  	int err = kstrtou16(buf, 16, &val);
  
  	if (err)
  		return err;
  
  	if (!strcmp(name, "arb_address")) {
  		dci_obj->reg_addr = val;
  		return count;
  	}
  
  	if (!strcmp(name, "arb_value"))
  		err = drci_wr_reg(usb_dev, dci_obj->reg_addr, val);
  	else if (!strcmp(name, "sync_ep"))
  		err = start_sync_ep(usb_dev, val);
  	else if (!get_static_reg_addr(rw_regs, name, &reg_addr))
  		err = drci_wr_reg(usb_dev, reg_addr, val);
  	else
  		return -EFAULT;
  
  	if (err < 0)
  		return err;
  
  	return count;
  }
  
  static MOST_DCI_RO_ATTR(ni_state);
  static MOST_DCI_RO_ATTR(packet_bandwidth);
  static MOST_DCI_RO_ATTR(node_address);
  static MOST_DCI_RO_ATTR(node_position);
  static MOST_DCI_WO_ATTR(sync_ep);
  static MOST_DCI_ATTR(mep_filter);
  static MOST_DCI_ATTR(mep_hash0);
  static MOST_DCI_ATTR(mep_hash1);
  static MOST_DCI_ATTR(mep_hash2);
  static MOST_DCI_ATTR(mep_hash3);
  static MOST_DCI_ATTR(mep_eui48_hi);
  static MOST_DCI_ATTR(mep_eui48_mi);
  static MOST_DCI_ATTR(mep_eui48_lo);
  static MOST_DCI_ATTR(arb_address);
  static MOST_DCI_ATTR(arb_value);
  
  /**
   * most_dci_def_attrs - array of default attribute files of the dci object
   */
  static struct attribute *most_dci_def_attrs[] = {
  	&most_dci_attr_ni_state.attr,
  	&most_dci_attr_packet_bandwidth.attr,
  	&most_dci_attr_node_address.attr,
  	&most_dci_attr_node_position.attr,
  	&most_dci_attr_sync_ep.attr,
  	&most_dci_attr_mep_filter.attr,
  	&most_dci_attr_mep_hash0.attr,
  	&most_dci_attr_mep_hash1.attr,
  	&most_dci_attr_mep_hash2.attr,
  	&most_dci_attr_mep_hash3.attr,
  	&most_dci_attr_mep_eui48_hi.attr,
  	&most_dci_attr_mep_eui48_mi.attr,
  	&most_dci_attr_mep_eui48_lo.attr,
  	&most_dci_attr_arb_address.attr,
  	&most_dci_attr_arb_value.attr,
  	NULL,
  };
  
  /**
   * DCI ktype
   */
  static struct kobj_type most_dci_ktype = {
  	.sysfs_ops = &most_dci_sysfs_ops,
  	.release = most_dci_release,
  	.default_attrs = most_dci_def_attrs,
  };
  
  /**
   * create_most_dci_obj - allocates a dci object
   * @parent: parent kobject
   *
   * This creates a dci object and registers it with sysfs.
   * Returns a pointer to the object or NULL when something went wrong.
   */
  static struct
  most_dci_obj *create_most_dci_obj(struct kobject *parent)
  {
  	struct most_dci_obj *most_dci = kzalloc(sizeof(*most_dci), GFP_KERNEL);
  	int retval;
  
  	if (!most_dci)
  		return NULL;
  
  	retval = kobject_init_and_add(&most_dci->kobj, &most_dci_ktype, parent,
  				      "dci");
  	if (retval) {
  		kobject_put(&most_dci->kobj);
  		return NULL;
  	}
  	return most_dci;
  }
  
  /**
   * destroy_most_dci_obj - DCI object release function
   * @p: pointer to dci object
   */
  static void destroy_most_dci_obj(struct most_dci_obj *p)
  {
  	kobject_put(&p->kobj);
  }
  
  /**
   * hdm_probe - probe function of USB device driver
   * @interface: Interface of the attached USB device
   * @id: Pointer to the USB ID table.
   *
   * This allocates and initializes the device instance, adds the new
   * entry to the internal list, scans the USB descriptors and registers
   * the interface with the core.
   * Additionally, the DCI objects are created and the hardware is sync'd.
   *
   * Return 0 on success. In case of an error a negative number is returned.
   */
  static int
  hdm_probe(struct usb_interface *interface, const struct usb_device_id *id)
  {
  	struct usb_host_interface *usb_iface_desc = interface->cur_altsetting;
  	struct usb_device *usb_dev = interface_to_usbdev(interface);
  	struct device *dev = &usb_dev->dev;
  	struct most_dev *mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
  	unsigned int i;
  	unsigned int num_endpoints;
  	struct most_channel_capability *tmp_cap;
  	struct usb_endpoint_descriptor *ep_desc;
  	int ret = 0;
  
  	if (!mdev)
  		goto exit_ENOMEM;
  
  	usb_set_intfdata(interface, mdev);
  	num_endpoints = usb_iface_desc->desc.bNumEndpoints;
  	mutex_init(&mdev->io_mutex);
  	INIT_WORK(&mdev->poll_work_obj, wq_netinfo);
  	timer_setup(&mdev->link_stat_timer, link_stat_timer_handler, 0);
  
  	mdev->usb_device = usb_dev;
  	mdev->link_stat_timer.expires = jiffies + (2 * HZ);
  
  	mdev->iface.mod = hdm_usb_fops.owner;
  	mdev->iface.interface = ITYPE_USB;
  	mdev->iface.configure = hdm_configure_channel;
  	mdev->iface.request_netinfo = hdm_request_netinfo;
  	mdev->iface.enqueue = hdm_enqueue;
  	mdev->iface.poison_channel = hdm_poison_channel;
  	mdev->iface.description = mdev->description;
  	mdev->iface.num_channels = num_endpoints;
  
  	snprintf(mdev->description, sizeof(mdev->description),
  		 "usb_device %d-%s:%d.%d",
  		 usb_dev->bus->busnum,
  		 usb_dev->devpath,
  		 usb_dev->config->desc.bConfigurationValue,
  		 usb_iface_desc->desc.bInterfaceNumber);
  
  	mdev->conf = kcalloc(num_endpoints, sizeof(*mdev->conf), GFP_KERNEL);
  	if (!mdev->conf)
  		goto exit_free;
  
  	mdev->cap = kcalloc(num_endpoints, sizeof(*mdev->cap), GFP_KERNEL);
  	if (!mdev->cap)
  		goto exit_free1;
  
  	mdev->iface.channel_vector = mdev->cap;
  	mdev->iface.priv = NULL;
  
  	mdev->ep_address =
  		kcalloc(num_endpoints, sizeof(*mdev->ep_address), GFP_KERNEL);
  	if (!mdev->ep_address)
  		goto exit_free2;
  
  	mdev->busy_urbs =
  		kcalloc(num_endpoints, sizeof(*mdev->busy_urbs), GFP_KERNEL);
  	if (!mdev->busy_urbs)
  		goto exit_free3;
  
  	tmp_cap = mdev->cap;
  	for (i = 0; i < num_endpoints; i++) {
  		ep_desc = &usb_iface_desc->endpoint[i].desc;
  		mdev->ep_address[i] = ep_desc->bEndpointAddress;
  		mdev->padding_active[i] = false;
  		mdev->is_channel_healthy[i] = true;
  
  		snprintf(&mdev->suffix[i][0], MAX_SUFFIX_LEN, "ep%02x",
  			 mdev->ep_address[i]);
  
  		tmp_cap->name_suffix = &mdev->suffix[i][0];
  		tmp_cap->buffer_size_packet = MAX_BUF_SIZE;
  		tmp_cap->buffer_size_streaming = MAX_BUF_SIZE;
  		tmp_cap->num_buffers_packet = BUF_CHAIN_SIZE;
  		tmp_cap->num_buffers_streaming = BUF_CHAIN_SIZE;
  		tmp_cap->data_type = MOST_CH_CONTROL | MOST_CH_ASYNC |
  				     MOST_CH_ISOC | MOST_CH_SYNC;
  		if (usb_endpoint_dir_in(ep_desc))
  			tmp_cap->direction = MOST_CH_RX;
  		else
  			tmp_cap->direction = MOST_CH_TX;
  		tmp_cap++;
  		init_usb_anchor(&mdev->busy_urbs[i]);
  		spin_lock_init(&mdev->channel_lock[i]);
  	}
  	dev_notice(dev, "claimed gadget: Vendor=%4.4x ProdID=%4.4x Bus=%02x Device=%02x\n",
  		   le16_to_cpu(usb_dev->descriptor.idVendor),
  		   le16_to_cpu(usb_dev->descriptor.idProduct),
  		   usb_dev->bus->busnum,
  		   usb_dev->devnum);
  
  	dev_notice(dev, "device path: /sys/bus/usb/devices/%d-%s:%d.%d\n",
  		   usb_dev->bus->busnum,
  		   usb_dev->devpath,
  		   usb_dev->config->desc.bConfigurationValue,
  		   usb_iface_desc->desc.bInterfaceNumber);
  
  	mdev->parent = most_register_interface(&mdev->iface);
  	if (IS_ERR(mdev->parent)) {
  		ret = PTR_ERR(mdev->parent);
  		goto exit_free4;
  	}
  
  	mutex_lock(&mdev->io_mutex);
  	if (le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81118 ||
  	    le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81119 ||
  	    le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81210) {
  		/* this increments the reference count of the instance
  		 * object of the core
  		 */
  		mdev->dci = create_most_dci_obj(mdev->parent);
  		if (!mdev->dci) {
  			mutex_unlock(&mdev->io_mutex);
  			most_deregister_interface(&mdev->iface);
  			ret = -ENOMEM;
  			goto exit_free4;
  		}
  
  		kobject_uevent(&mdev->dci->kobj, KOBJ_ADD);
  		mdev->dci->usb_device = mdev->usb_device;
  	}
  	mutex_unlock(&mdev->io_mutex);
  	return 0;
  
  exit_free4:
  	kfree(mdev->busy_urbs);
  exit_free3:
  	kfree(mdev->ep_address);
  exit_free2:
  	kfree(mdev->cap);
  exit_free1:
  	kfree(mdev->conf);
  exit_free:
  	kfree(mdev);
  exit_ENOMEM:
  	if (ret == 0 || ret == -ENOMEM) {
  		ret = -ENOMEM;
  		dev_err(dev, "out of memory\n");
  	}
  	return ret;
  }
  
  /**
   * hdm_disconnect - disconnect function of USB device driver
   * @interface: Interface of the attached USB device
   *
   * This deregisters the interface with the core, removes the kernel timer
   * and frees resources.
   *
   * Context: hub kernel thread
   */
  static void hdm_disconnect(struct usb_interface *interface)
  {
  	struct most_dev *mdev = usb_get_intfdata(interface);
  
  	mutex_lock(&mdev->io_mutex);
  	usb_set_intfdata(interface, NULL);
  	mdev->usb_device = NULL;
  	mutex_unlock(&mdev->io_mutex);
  
  	del_timer_sync(&mdev->link_stat_timer);
  	cancel_work_sync(&mdev->poll_work_obj);
  
  	destroy_most_dci_obj(mdev->dci);
  	most_deregister_interface(&mdev->iface);
  
  	kfree(mdev->busy_urbs);
  	kfree(mdev->cap);
  	kfree(mdev->conf);
  	kfree(mdev->ep_address);
  	kfree(mdev);
  }
  
  static struct usb_driver hdm_usb = {
  	.name = "hdm_usb",
  	.id_table = usbid,
  	.probe = hdm_probe,
  	.disconnect = hdm_disconnect,
  };
  
  module_usb_driver(hdm_usb);
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
  MODULE_DESCRIPTION("HDM_4_USB");
  