[PATCH RFC] drivers: most: add USB adapter driver

* [PATCH RFC] drivers: most: add USB adapter driver
@ 2020-05-11  9:51 Christian Gromm
  2020-05-11 11:47 ` Greg KH
  2020-05-11 14:25 ` Randy Dunlap
  0 siblings, 2 replies; 6+ messages in thread
From: Christian Gromm @ 2020-05-11  9:51 UTC (permalink / raw)
  To: gregkh; +Cc: Christian Gromm, driverdev-devel, linux-usb

This patch adds the MOST USB adapter driver to the stable branch. This is
a follow-up to commit <b276527>.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
---
 drivers/most/Kconfig          |    6 +
 drivers/most/Makefile         |    2 +
 drivers/most/usb/Kconfig      |   14 +
 drivers/most/usb/Makefile     |    4 +
 drivers/most/usb/usb.c        | 1262 +++++++++++++++++++++++++++++++++++++++++
 drivers/staging/most/Kconfig  |    2 -
 drivers/staging/most/Makefile |    1 -
 7 files changed, 1288 insertions(+), 3 deletions(-)
 create mode 100644 drivers/most/usb/Kconfig
 create mode 100644 drivers/most/usb/Makefile
 create mode 100644 drivers/most/usb/usb.c

diff --git a/drivers/most/Kconfig b/drivers/most/Kconfig
index 58d7999..400ed52 100644
--- a/drivers/most/Kconfig
+++ b/drivers/most/Kconfig
@@ -13,3 +13,9 @@ menuconfig MOST
 	  module will be called most_core.
 
 	  If in doubt, say N here.
+
+if MOST
+
+source "drivers/most/usb/Kconfig"
+
+endif
diff --git a/drivers/most/Makefile b/drivers/most/Makefile
index e810cd3..4daa370 100644
--- a/drivers/most/Makefile
+++ b/drivers/most/Makefile
@@ -2,3 +2,5 @@
 obj-$(CONFIG_MOST) += most_core.o
 most_core-y :=	core.o \
 		configfs.o
+
+obj-$(CONFIG_MOST_USB)	+= usb/
diff --git a/drivers/most/usb/Kconfig b/drivers/most/usb/Kconfig
new file mode 100644
index 0000000..a86f1f6
--- /dev/null
+++ b/drivers/most/usb/Kconfig
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# MOST USB configuration
+#
+
+config MOST_USB
+	tristate "USB"
+	depends on USB && NET
+	help
+	  Say Y here if you want to connect via USB to network tranceiver.
+	  This device driver depends on the networking AIM.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_usb.
diff --git a/drivers/most/usb/Makefile b/drivers/most/usb/Makefile
new file mode 100644
index 0000000..c2b2073
--- /dev/null
+++ b/drivers/most/usb/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_MOST_USB) += most_usb.o
+
+most_usb-objs := usb.o
diff --git a/drivers/most/usb/usb.c b/drivers/most/usb/usb.c
new file mode 100644
index 0000000..daa5e4b
--- /dev/null
+++ b/drivers/most/usb/usb.c
@@ -0,0 +1,1262 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * usb.c - Hardware dependent module for USB
+ *
+ * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#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 <linux/most.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 device dev;
+	struct usb_device *usb_device;
+	u16 reg_addr;
+};
+
+#define to_dci_obj(p) container_of(p, struct most_dci_obj, dev)
+
+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
+ * @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 device dev;
+	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 *most_iface,
+			   unsigned char link_state, unsigned char *addrs);
+};
+
+#define to_mdev(d) container_of(d, struct most_dev, iface)
+#define to_mdev_from_dev(d) container_of(d, struct most_dev, dev)
+#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 (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 -EINVAL;
+	num_frames = mbo->buffer_length / frame_size;
+
+	if (num_frames < 1) {
+		dev_err(&mdev->usb_device->dev,
+			"Missed minimal transfer unit.\n");
+		return -EINVAL;
+	}
+
+	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 -EINVAL;
+	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;
+	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(&mdev->usb_device->dev,
+				 "Broken pipe on ep%02x\n",
+				 mdev->ep_address[channel]);
+			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 pipe on ep%02x\n",
+				 mdev->ep_address[channel]);
+			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 ep%02x\n",
+				 mdev->ep_address[channel]);
+			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 = to_mdev(iface);
+	struct most_channel_config *conf;
+	int retval = 0;
+	struct urb *urb;
+	unsigned long length;
+	void *virt_address;
+
+	if (!mbo)
+		return -EINVAL;
+	if (iface->num_channels <= channel || channel < 0)
+		return -ECHRNG;
+
+	conf = &mdev->conf[channel];
+
+	mutex_lock(&mdev->io_mutex);
+	if (!mdev->usb_device) {
+		retval = -ENODEV;
+		goto unlock_io_mutex;
+	}
+
+	urb = usb_alloc_urb(NO_ISOCHRONOUS_URB, GFP_ATOMIC);
+	if (!urb) {
+		retval = -ENOMEM;
+		goto unlock_io_mutex;
+	}
+
+	if ((conf->direction & MOST_CH_TX) && mdev->padding_active[channel] &&
+	    hdm_add_padding(mdev, channel, mbo)) {
+		retval = -EINVAL;
+		goto err_free_urb;
+	}
+
+	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 &&
+		    conf->data_type != MOST_CH_SYNC)
+			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(&mdev->usb_device->dev,
+			"URB submit failed with error %d.\n", retval);
+		goto err_unanchor_urb;
+	}
+	goto unlock_io_mutex;
+
+err_unanchor_urb:
+	usb_unanchor_urb(urb);
+err_free_urb:
+	usb_free_urb(urb);
+unlock_io_mutex:
+	mutex_unlock(&mdev->io_mutex);
+	return retval;
+}
+
+static void *hdm_dma_alloc(struct mbo *mbo, u32 size)
+{
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+
+	return usb_alloc_coherent(mdev->usb_device, size, GFP_KERNEL,
+				  &mbo->bus_address);
+}
+
+static void hdm_dma_free(struct mbo *mbo, u32 size)
+{
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+
+	usb_free_coherent(mdev->usb_device, size, mbo->virt_address,
+			  mbo->bus_address);
+}
+
+/**
+ * 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 (!conf) {
+		dev_err(dev, "Bad config pointer.\n");
+		return -EINVAL;
+	}
+	if (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 = 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");
+
+	/* If the functional Stall condition has been set on an
+	 * asynchronous rx channel, we need to clear the tx channel
+	 * too, since the hardware runs its clean-up sequence on both
+	 * channels, as they are physically one on the network.
+	 *
+	 * The USB interface that exposes the asynchronous channels
+	 * contains always two endpoints, and two only.
+	 */
+	if (mdev->conf[channel].data_type == MOST_CH_ASYNC &&
+	    mdev->conf[channel].direction == MOST_CH_RX) {
+		int peer = 1 - channel;
+		int snd_pipe = usb_sndbulkpipe(mdev->usb_device,
+					       mdev->ep_address[peer]);
+		usb_clear_halt(mdev->usb_device, snd_pipe);
+	}
+	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 */
+};
+
+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 value_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	const char *name = attr->attr.name;
+	struct most_dci_obj *dci_obj = to_dci_obj(dev);
+	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 value_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	u16 val;
+	u16 reg_addr;
+	const char *name = attr->attr.name;
+	struct most_dci_obj *dci_obj = to_dci_obj(dev);
+	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 DEVICE_ATTR(ni_state, 0444, value_show, NULL);
+static DEVICE_ATTR(packet_bandwidth, 0444, value_show, NULL);
+static DEVICE_ATTR(node_address, 0444, value_show, NULL);
+static DEVICE_ATTR(node_position, 0444, value_show, NULL);
+static DEVICE_ATTR(sync_ep, 0200, NULL, value_store);
+static DEVICE_ATTR(mep_filter, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash0, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash1, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash2, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash3, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_hi, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_mi, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_lo, 0644, value_show, value_store);
+static DEVICE_ATTR(arb_address, 0644, value_show, value_store);
+static DEVICE_ATTR(arb_value, 0644, value_show, value_store);
+
+static struct attribute *dci_attrs[] = {
+	&dev_attr_ni_state.attr,
+	&dev_attr_packet_bandwidth.attr,
+	&dev_attr_node_address.attr,
+	&dev_attr_node_position.attr,
+	&dev_attr_sync_ep.attr,
+	&dev_attr_mep_filter.attr,
+	&dev_attr_mep_hash0.attr,
+	&dev_attr_mep_hash1.attr,
+	&dev_attr_mep_hash2.attr,
+	&dev_attr_mep_hash3.attr,
+	&dev_attr_mep_eui48_hi.attr,
+	&dev_attr_mep_eui48_mi.attr,
+	&dev_attr_mep_eui48_lo.attr,
+	&dev_attr_arb_address.attr,
+	&dev_attr_arb_value.attr,
+	NULL,
+};
+
+static struct attribute_group dci_attr_group = {
+	.attrs = dci_attrs,
+};
+
+static const struct attribute_group *dci_attr_groups[] = {
+	&dci_attr_group,
+	NULL,
+};
+
+static void release_dci(struct device *dev)
+{
+	struct most_dci_obj *dci = to_dci_obj(dev);
+
+	kfree(dci);
+}
+
+static void release_mdev(struct device *dev)
+{
+	struct most_dev *mdev = to_mdev_from_dev(dev);
+
+	kfree(mdev);
+}
+/**
+ * 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 err_out_of_memory;
+
+	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.dev = &mdev->dev;
+	mdev->iface.driver_dev = &interface->dev;
+	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.dma_alloc = hdm_dma_alloc;
+	mdev->iface.dma_free = hdm_dma_free;
+	mdev->iface.description = mdev->description;
+	mdev->iface.num_channels = num_endpoints;
+
+	snprintf(mdev->description, sizeof(mdev->description),
+		 "%d-%s:%d.%d",
+		 usb_dev->bus->busnum,
+		 usb_dev->devpath,
+		 usb_dev->config->desc.bConfigurationValue,
+		 usb_iface_desc->desc.bInterfaceNumber);
+
+	mdev->dev.init_name = mdev->description;
+	mdev->dev.parent = &interface->dev;
+	mdev->dev.release = release_mdev;
+	mdev->conf = kcalloc(num_endpoints, sizeof(*mdev->conf), GFP_KERNEL);
+	if (!mdev->conf)
+		goto err_free_mdev;
+
+	mdev->cap = kcalloc(num_endpoints, sizeof(*mdev->cap), GFP_KERNEL);
+	if (!mdev->cap)
+		goto err_free_conf;
+
+	mdev->iface.channel_vector = mdev->cap;
+	mdev->ep_address =
+		kcalloc(num_endpoints, sizeof(*mdev->ep_address), GFP_KERNEL);
+	if (!mdev->ep_address)
+		goto err_free_cap;
+
+	mdev->busy_urbs =
+		kcalloc(num_endpoints, sizeof(*mdev->busy_urbs), GFP_KERNEL);
+	if (!mdev->busy_urbs)
+		goto err_free_ep_address;
+
+	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);
+
+	ret = most_register_interface(&mdev->iface);
+	if (ret)
+		goto err_free_busy_urbs;
+
+	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) {
+		mdev->dci = kzalloc(sizeof(*mdev->dci), GFP_KERNEL);
+		if (!mdev->dci) {
+			mutex_unlock(&mdev->io_mutex);
+			most_deregister_interface(&mdev->iface);
+			ret = -ENOMEM;
+			goto err_free_busy_urbs;
+		}
+
+		mdev->dci->dev.init_name = "dci";
+		mdev->dci->dev.parent = get_device(mdev->iface.dev);
+		mdev->dci->dev.groups = dci_attr_groups;
+		mdev->dci->dev.release = release_dci;
+		if (device_register(&mdev->dci->dev)) {
+			mutex_unlock(&mdev->io_mutex);
+			most_deregister_interface(&mdev->iface);
+			ret = -ENOMEM;
+			goto err_free_dci;
+		}
+		mdev->dci->usb_device = mdev->usb_device;
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+err_free_dci:
+	put_device(&mdev->dci->dev);
+err_free_busy_urbs:
+	kfree(mdev->busy_urbs);
+err_free_ep_address:
+	kfree(mdev->ep_address);
+err_free_cap:
+	kfree(mdev->cap);
+err_free_conf:
+	kfree(mdev->conf);
+err_free_mdev:
+	put_device(&mdev->dev);
+err_out_of_memory:
+	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);
+
+	if (mdev->dci)
+		device_unregister(&mdev->dci->dev);
+	most_deregister_interface(&mdev->iface);
+
+	kfree(mdev->busy_urbs);
+	kfree(mdev->cap);
+	kfree(mdev->conf);
+	kfree(mdev->ep_address);
+	put_device(&mdev->dev);
+}
+
+static int hdm_suspend(struct usb_interface *interface, pm_message_t message)
+{
+	struct most_dev *mdev = usb_get_intfdata(interface);
+	int i;
+
+	mutex_lock(&mdev->io_mutex);
+	for (i = 0; i < mdev->iface.num_channels; i++) {
+		most_stop_enqueue(&mdev->iface, i);
+		usb_kill_anchored_urbs(&mdev->busy_urbs[i]);
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+}
+
+static int hdm_resume(struct usb_interface *interface)
+{
+	struct most_dev *mdev = usb_get_intfdata(interface);
+	int i;
+
+	mutex_lock(&mdev->io_mutex);
+	for (i = 0; i < mdev->iface.num_channels; i++)
+		most_resume_enqueue(&mdev->iface, i);
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+}
+
+static struct usb_driver hdm_usb = {
+	.name = "hdm_usb",
+	.id_table = usbid,
+	.probe = hdm_probe,
+	.disconnect = hdm_disconnect,
+	.resume = hdm_resume,
+	.suspend = hdm_suspend,
+};
+
+module_usb_driver(hdm_usb);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_DESCRIPTION("HDM_4_USB");
diff --git a/drivers/staging/most/Kconfig b/drivers/staging/most/Kconfig
index c5a99f7..c35fb34f 100644
--- a/drivers/staging/most/Kconfig
+++ b/drivers/staging/most/Kconfig
@@ -30,6 +30,4 @@ source "drivers/staging/most/dim2/Kconfig"
 
 source "drivers/staging/most/i2c/Kconfig"
 
-source "drivers/staging/most/usb/Kconfig"
-
 endif
diff --git a/drivers/staging/most/Makefile b/drivers/staging/most/Makefile
index a803a98..7c10b84 100644
--- a/drivers/staging/most/Makefile
+++ b/drivers/staging/most/Makefile
@@ -6,4 +6,3 @@ obj-$(CONFIG_MOST_SOUND)	+= sound/
 obj-$(CONFIG_MOST_VIDEO)	+= video/
 obj-$(CONFIG_MOST_DIM2)	+= dim2/
 obj-$(CONFIG_MOST_I2C)	+= i2c/
-obj-$(CONFIG_MOST_USB)	+= usb/
-- 
2.7.4

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