Initial import

1 files changed, 876 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/sur40.c b/drivers/input/touchscreen/sur40.c
new file mode 100644
index 000000000..a24eba5ea
--- /dev/null
+++ b/drivers/input/touchscreen/sur40.c
@@ -0,0 +1,876 @@
+/*
+ * Surface2.0/SUR40/PixelSense input driver
+ *
+ * Copyright (c) 2014 by Florian 'floe' Echtler <floe@butterbrot.org>
+ *
+ * Derived from the USB Skeleton driver 1.1,
+ * Copyright (c) 2003 Greg Kroah-Hartman (greg@kroah.com)
+ *
+ * and from the Apple USB BCM5974 multitouch driver,
+ * Copyright (c) 2008 Henrik Rydberg (rydberg@euromail.se)
+ *
+ * and from the generic hid-multitouch driver,
+ * Copyright (c) 2010-2012 Stephane Chatty <chatty@enac.fr>
+ *
+ * and from the v4l2-pci-skeleton driver,
+ * Copyright (c) Copyright 2014 Cisco Systems, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/completion.h>
+#include <linux/uaccess.h>
+#include <linux/usb.h>
+#include <linux/printk.h>
+#include <linux/input-polldev.h>
+#include <linux/input/mt.h>
+#include <linux/usb/input.h>
+#include <linux/videodev2.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-dev.h>
+#include <media/v4l2-ioctl.h>
+#include <media/videobuf2-dma-sg.h>
+
+/* read 512 bytes from endpoint 0x86 -> get header + blobs */
+struct sur40_header {
+
+	__le16 type;       /* always 0x0001 */
+	__le16 count;      /* count of blobs (if 0: continue prev. packet) */
+
+	__le32 packet_id;  /* unique ID for all packets in one frame */
+
+	__le32 timestamp;  /* milliseconds (inc. by 16 or 17 each frame) */
+	__le32 unknown;    /* "epoch?" always 02/03 00 00 00 */
+
+} __packed;
+
+struct sur40_blob {
+
+	__le16 blob_id;
+
+	u8 action;         /* 0x02 = enter/exit, 0x03 = update (?) */
+	u8 unknown;        /* always 0x01 or 0x02 (no idea what this is?) */
+
+	__le16 bb_pos_x;   /* upper left corner of bounding box */
+	__le16 bb_pos_y;
+
+	__le16 bb_size_x;  /* size of bounding box */
+	__le16 bb_size_y;
+
+	__le16 pos_x;      /* finger tip position */
+	__le16 pos_y;
+
+	__le16 ctr_x;      /* centroid position */
+	__le16 ctr_y;
+
+	__le16 axis_x;     /* somehow related to major/minor axis, mostly: */
+	__le16 axis_y;     /* axis_x == bb_size_y && axis_y == bb_size_x */
+
+	__le32 angle;      /* orientation in radians relative to x axis -
+	                      actually an IEEE754 float, don't use in kernel */
+
+	__le32 area;       /* size in pixels/pressure (?) */
+
+	u8 padding[32];
+
+} __packed;
+
+/* combined header/blob data */
+struct sur40_data {
+	struct sur40_header header;
+	struct sur40_blob   blobs[];
+} __packed;
+
+/* read 512 bytes from endpoint 0x82 -> get header below
+ * continue reading 16k blocks until header.size bytes read */
+struct sur40_image_header {
+	__le32 magic;     /* "SUBF" */
+	__le32 packet_id;
+	__le32 size;      /* always 0x0007e900 = 960x540 */
+	__le32 timestamp; /* milliseconds (increases by 16 or 17 each frame) */
+	__le32 unknown;   /* "epoch?" always 02/03 00 00 00 */
+} __packed;
+
+/* version information */
+#define DRIVER_SHORT   "sur40"
+#define DRIVER_LONG    "Samsung SUR40"
+#define DRIVER_AUTHOR  "Florian 'floe' Echtler <floe@butterbrot.org>"
+#define DRIVER_DESC    "Surface2.0/SUR40/PixelSense input driver"
+
+/* vendor and device IDs */
+#define ID_MICROSOFT 0x045e
+#define ID_SUR40     0x0775
+
+/* sensor resolution */
+#define SENSOR_RES_X 1920
+#define SENSOR_RES_Y 1080
+
+/* touch data endpoint */
+#define TOUCH_ENDPOINT 0x86
+
+/* video data endpoint */
+#define VIDEO_ENDPOINT 0x82
+
+/* video header fields */
+#define VIDEO_HEADER_MAGIC 0x46425553
+#define VIDEO_PACKET_SIZE  16384
+
+/* polling interval (ms) */
+#define POLL_INTERVAL 10
+
+/* maximum number of contacts FIXME: this is a guess? */
+#define MAX_CONTACTS 64
+
+/* control commands */
+#define SUR40_GET_VERSION 0xb0 /* 12 bytes string    */
+#define SUR40_UNKNOWN1    0xb3 /*  5 bytes           */
+#define SUR40_UNKNOWN2    0xc1 /* 24 bytes           */
+
+#define SUR40_GET_STATE   0xc5 /*  4 bytes state (?) */
+#define SUR40_GET_SENSORS 0xb1 /*  8 bytes sensors   */
+
+/* master device state */
+struct sur40_state {
+
+	struct usb_device *usbdev;
+	struct device *dev;
+	struct input_polled_dev *input;
+
+	struct v4l2_device v4l2;
+	struct video_device vdev;
+	struct mutex lock;
+
+	struct vb2_queue queue;
+	struct vb2_alloc_ctx *alloc_ctx;
+	struct list_head buf_list;
+	spinlock_t qlock;
+	int sequence;
+
+	struct sur40_data *bulk_in_buffer;
+	size_t bulk_in_size;
+	u8 bulk_in_epaddr;
+
+	char phys[64];
+};
+
+struct sur40_buffer {
+	struct vb2_buffer vb;
+	struct list_head list;
+};
+
+/* forward declarations */
+static const struct video_device sur40_video_device;
+static const struct v4l2_pix_format sur40_video_format;
+static const struct vb2_queue sur40_queue;
+static void sur40_process_video(struct sur40_state *sur40);
+
+/*
+ * Note: an earlier, non-public version of this driver used USB_RECIP_ENDPOINT
+ * here by mistake which is very likely to have corrupted the firmware EEPROM
+ * on two separate SUR40 devices. Thanks to Alan Stern who spotted this bug.
+ * Should you ever run into a similar problem, the background story to this
+ * incident and instructions on how to fix the corrupted EEPROM are available
+ * at https://floe.butterbrot.org/matrix/hacking/surface/brick.html
+*/
+
+/* command wrapper */
+static int sur40_command(struct sur40_state *dev,
+			 u8 command, u16 index, void *buffer, u16 size)
+{
+	return usb_control_msg(dev->usbdev, usb_rcvctrlpipe(dev->usbdev, 0),
+			       command,
+			       USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
+			       0x00, index, buffer, size, 1000);
+}
+
+/* Initialization routine, called from sur40_open */
+static int sur40_init(struct sur40_state *dev)
+{
+	int result;
+	u8 buffer[24];
+
+	/* stupidly replay the original MS driver init sequence */
+	result = sur40_command(dev, SUR40_GET_VERSION, 0x00, buffer, 12);
+	if (result < 0)
+		return result;
+
+	result = sur40_command(dev, SUR40_GET_VERSION, 0x01, buffer, 12);
+	if (result < 0)
+		return result;
+
+	result = sur40_command(dev, SUR40_GET_VERSION, 0x02, buffer, 12);
+	if (result < 0)
+		return result;
+
+	result = sur40_command(dev, SUR40_UNKNOWN2,    0x00, buffer, 24);
+	if (result < 0)
+		return result;
+
+	result = sur40_command(dev, SUR40_UNKNOWN1,    0x00, buffer,  5);
+	if (result < 0)
+		return result;
+
+	result = sur40_command(dev, SUR40_GET_VERSION, 0x03, buffer, 12);
+
+	/*
+	 * Discard the result buffer - no known data inside except
+	 * some version strings, maybe extract these sometime...
+	 */
+
+	return result;
+}
+
+/*
+ * Callback routines from input_polled_dev
+ */
+
+/* Enable the device, polling will now start. */
+static void sur40_open(struct input_polled_dev *polldev)
+{
+	struct sur40_state *sur40 = polldev->private;
+
+	dev_dbg(sur40->dev, "open\n");
+	sur40_init(sur40);
+}
+
+/* Disable device, polling has stopped. */
+static void sur40_close(struct input_polled_dev *polldev)
+{
+	struct sur40_state *sur40 = polldev->private;
+
+	dev_dbg(sur40->dev, "close\n");
+	/*
+	 * There is no known way to stop the device, so we simply
+	 * stop polling.
+	 */
+}
+
+/*
+ * This function is called when a whole contact has been processed,
+ * so that it can assign it to a slot and store the data there.
+ */
+static void sur40_report_blob(struct sur40_blob *blob, struct input_dev *input)
+{
+	int wide, major, minor;
+
+	int bb_size_x = le16_to_cpu(blob->bb_size_x);
+	int bb_size_y = le16_to_cpu(blob->bb_size_y);
+
+	int pos_x = le16_to_cpu(blob->pos_x);
+	int pos_y = le16_to_cpu(blob->pos_y);
+
+	int ctr_x = le16_to_cpu(blob->ctr_x);
+	int ctr_y = le16_to_cpu(blob->ctr_y);
+
+	int slotnum = input_mt_get_slot_by_key(input, blob->blob_id);
+	if (slotnum < 0 || slotnum >= MAX_CONTACTS)
+		return;
+
+	input_mt_slot(input, slotnum);
+	input_mt_report_slot_state(input, MT_TOOL_FINGER, 1);
+	wide = (bb_size_x > bb_size_y);
+	major = max(bb_size_x, bb_size_y);
+	minor = min(bb_size_x, bb_size_y);
+
+	input_report_abs(input, ABS_MT_POSITION_X, pos_x);
+	input_report_abs(input, ABS_MT_POSITION_Y, pos_y);
+	input_report_abs(input, ABS_MT_TOOL_X, ctr_x);
+	input_report_abs(input, ABS_MT_TOOL_Y, ctr_y);
+
+	/* TODO: use a better orientation measure */
+	input_report_abs(input, ABS_MT_ORIENTATION, wide);
+	input_report_abs(input, ABS_MT_TOUCH_MAJOR, major);
+	input_report_abs(input, ABS_MT_TOUCH_MINOR, minor);
+}
+
+/* core function: poll for new input data */
+static void sur40_poll(struct input_polled_dev *polldev)
+{
+	struct sur40_state *sur40 = polldev->private;
+	struct input_dev *input = polldev->input;
+	int result, bulk_read, need_blobs, packet_blobs, i;
+	u32 uninitialized_var(packet_id);
+
+	struct sur40_header *header = &sur40->bulk_in_buffer->header;
+	struct sur40_blob *inblob = &sur40->bulk_in_buffer->blobs[0];
+
+	dev_dbg(sur40->dev, "poll\n");
+
+	need_blobs = -1;
+
+	do {
+
+		/* perform a blocking bulk read to get data from the device */
+		result = usb_bulk_msg(sur40->usbdev,
+			usb_rcvbulkpipe(sur40->usbdev, sur40->bulk_in_epaddr),
+			sur40->bulk_in_buffer, sur40->bulk_in_size,
+			&bulk_read, 1000);
+
+		dev_dbg(sur40->dev, "received %d bytes\n", bulk_read);
+
+		if (result < 0) {
+			dev_err(sur40->dev, "error in usb_bulk_read\n");
+			return;
+		}
+
+		result = bulk_read - sizeof(struct sur40_header);
+
+		if (result % sizeof(struct sur40_blob) != 0) {
+			dev_err(sur40->dev, "transfer size mismatch\n");
+			return;
+		}
+
+		/* first packet? */
+		if (need_blobs == -1) {
+			need_blobs = le16_to_cpu(header->count);
+			dev_dbg(sur40->dev, "need %d blobs\n", need_blobs);
+			packet_id = le32_to_cpu(header->packet_id);
+		}
+
+		/*
+		 * Sanity check. when video data is also being retrieved, the
+		 * packet ID will usually increase in the middle of a series
+		 * instead of at the end.
+		 */
+		if (packet_id != header->packet_id)
+			dev_warn(sur40->dev, "packet ID mismatch\n");
+
+		packet_blobs = result / sizeof(struct sur40_blob);
+		dev_dbg(sur40->dev, "received %d blobs\n", packet_blobs);
+
+		/* packets always contain at least 4 blobs, even if empty */
+		if (packet_blobs > need_blobs)
+			packet_blobs = need_blobs;
+
+		for (i = 0; i < packet_blobs; i++) {
+			need_blobs--;
+			dev_dbg(sur40->dev, "processing blob\n");
+			sur40_report_blob(&(inblob[i]), input);
+		}
+
+	} while (need_blobs > 0);
+
+	input_mt_sync_frame(input);
+	input_sync(input);
+
+	sur40_process_video(sur40);
+}
+
+/* deal with video data */
+static void sur40_process_video(struct sur40_state *sur40)
+{
+
+	struct sur40_image_header *img = (void *)(sur40->bulk_in_buffer);
+	struct sur40_buffer *new_buf;
+	struct usb_sg_request sgr;
+	struct sg_table *sgt;
+	int result, bulk_read;
+
+	if (!vb2_start_streaming_called(&sur40->queue))
+		return;
+
+	/* get a new buffer from the list */
+	spin_lock(&sur40->qlock);
+	if (list_empty(&sur40->buf_list)) {
+		dev_dbg(sur40->dev, "buffer queue empty\n");
+		spin_unlock(&sur40->qlock);
+		return;
+	}
+	new_buf = list_entry(sur40->buf_list.next, struct sur40_buffer, list);
+	list_del(&new_buf->list);
+	spin_unlock(&sur40->qlock);
+
+	/* retrieve data via bulk read */
+	result = usb_bulk_msg(sur40->usbdev,
+			usb_rcvbulkpipe(sur40->usbdev, VIDEO_ENDPOINT),
+			sur40->bulk_in_buffer, sur40->bulk_in_size,
+			&bulk_read, 1000);
+
+	if (result < 0) {
+		dev_err(sur40->dev, "error in usb_bulk_read\n");
+		goto err_poll;
+	}
+
+	if (bulk_read != sizeof(struct sur40_image_header)) {
+		dev_err(sur40->dev, "received %d bytes (%zd expected)\n",
+			bulk_read, sizeof(struct sur40_image_header));
+		goto err_poll;
+	}
+
+	if (le32_to_cpu(img->magic) != VIDEO_HEADER_MAGIC) {
+		dev_err(sur40->dev, "image magic mismatch\n");
+		goto err_poll;
+	}
+
+	if (le32_to_cpu(img->size) != sur40_video_format.sizeimage) {
+		dev_err(sur40->dev, "image size mismatch\n");
+		goto err_poll;
+	}
+
+	sgt = vb2_dma_sg_plane_desc(&new_buf->vb, 0);
+
+	result = usb_sg_init(&sgr, sur40->usbdev,
+		usb_rcvbulkpipe(sur40->usbdev, VIDEO_ENDPOINT), 0,
+		sgt->sgl, sgt->nents, sur40_video_format.sizeimage, 0);
+	if (result < 0) {
+		dev_err(sur40->dev, "error %d in usb_sg_init\n", result);
+		goto err_poll;
+	}
+
+	usb_sg_wait(&sgr);
+	if (sgr.status < 0) {
+		dev_err(sur40->dev, "error %d in usb_sg_wait\n", sgr.status);
+		goto err_poll;
+	}
+
+	/* mark as finished */
+	v4l2_get_timestamp(&new_buf->vb.v4l2_buf.timestamp);
+	new_buf->vb.v4l2_buf.sequence = sur40->sequence++;
+	new_buf->vb.v4l2_buf.field = V4L2_FIELD_NONE;
+	vb2_buffer_done(&new_buf->vb, VB2_BUF_STATE_DONE);
+	return;
+
+err_poll:
+	vb2_buffer_done(&new_buf->vb, VB2_BUF_STATE_ERROR);
+}
+
+/* Initialize input device parameters. */
+static void sur40_input_setup(struct input_dev *input_dev)
+{
+	__set_bit(EV_KEY, input_dev->evbit);
+	__set_bit(EV_ABS, input_dev->evbit);
+
+	input_set_abs_params(input_dev, ABS_MT_POSITION_X,
+			     0, SENSOR_RES_X, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_POSITION_Y,
+			     0, SENSOR_RES_Y, 0, 0);
+
+	input_set_abs_params(input_dev, ABS_MT_TOOL_X,
+			     0, SENSOR_RES_X, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_TOOL_Y,
+			     0, SENSOR_RES_Y, 0, 0);
+
+	/* max value unknown, but major/minor axis
+	 * can never be larger than screen */
+	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR,
+			     0, SENSOR_RES_X, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_TOUCH_MINOR,
+			     0, SENSOR_RES_Y, 0, 0);
+
+	input_set_abs_params(input_dev, ABS_MT_ORIENTATION, 0, 1, 0, 0);
+
+	input_mt_init_slots(input_dev, MAX_CONTACTS,
+			    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+}
+
+/* Check candidate USB interface. */
+static int sur40_probe(struct usb_interface *interface,
+		       const struct usb_device_id *id)
+{
+	struct usb_device *usbdev = interface_to_usbdev(interface);
+	struct sur40_state *sur40;
+	struct usb_host_interface *iface_desc;
+	struct usb_endpoint_descriptor *endpoint;
+	struct input_polled_dev *poll_dev;
+	int error;
+
+	/* Check if we really have the right interface. */
+	iface_desc = &interface->altsetting[0];
+	if (iface_desc->desc.bInterfaceClass != 0xFF)
+		return -ENODEV;
+
+	/* Use endpoint #4 (0x86). */
+	endpoint = &iface_desc->endpoint[4].desc;
+	if (endpoint->bEndpointAddress != TOUCH_ENDPOINT)
+		return -ENODEV;
+
+	/* Allocate memory for our device state and initialize it. */
+	sur40 = kzalloc(sizeof(struct sur40_state), GFP_KERNEL);
+	if (!sur40)
+		return -ENOMEM;
+
+	poll_dev = input_allocate_polled_device();
+	if (!poll_dev) {
+		error = -ENOMEM;
+		goto err_free_dev;
+	}
+
+	/* initialize locks/lists */
+	INIT_LIST_HEAD(&sur40->buf_list);
+	spin_lock_init(&sur40->qlock);
+	mutex_init(&sur40->lock);
+
+	/* Set up polled input device control structure */
+	poll_dev->private = sur40;
+	poll_dev->poll_interval = POLL_INTERVAL;
+	poll_dev->open = sur40_open;
+	poll_dev->poll = sur40_poll;
+	poll_dev->close = sur40_close;
+
+	/* Set up regular input device structure */
+	sur40_input_setup(poll_dev->input);
+
+	poll_dev->input->name = DRIVER_LONG;
+	usb_to_input_id(usbdev, &poll_dev->input->id);
+	usb_make_path(usbdev, sur40->phys, sizeof(sur40->phys));
+	strlcat(sur40->phys, "/input0", sizeof(sur40->phys));
+	poll_dev->input->phys = sur40->phys;
+	poll_dev->input->dev.parent = &interface->dev;
+
+	sur40->usbdev = usbdev;
+	sur40->dev = &interface->dev;
+	sur40->input = poll_dev;
+
+	/* use the bulk-in endpoint tested above */
+	sur40->bulk_in_size = usb_endpoint_maxp(endpoint);
+	sur40->bulk_in_epaddr = endpoint->bEndpointAddress;
+	sur40->bulk_in_buffer = kmalloc(sur40->bulk_in_size, GFP_KERNEL);
+	if (!sur40->bulk_in_buffer) {
+		dev_err(&interface->dev, "Unable to allocate input buffer.");
+		error = -ENOMEM;
+		goto err_free_polldev;
+	}
+
+	/* register the polled input device */
+	error = input_register_polled_device(poll_dev);
+	if (error) {
+		dev_err(&interface->dev,
+			"Unable to register polled input device.");
+		goto err_free_buffer;
+	}
+
+	/* register the video master device */
+	snprintf(sur40->v4l2.name, sizeof(sur40->v4l2.name), "%s", DRIVER_LONG);
+	error = v4l2_device_register(sur40->dev, &sur40->v4l2);
+	if (error) {
+		dev_err(&interface->dev,
+			"Unable to register video master device.");
+		goto err_unreg_v4l2;
+	}
+
+	/* initialize the lock and subdevice */
+	sur40->queue = sur40_queue;
+	sur40->queue.drv_priv = sur40;
+	sur40->queue.lock = &sur40->lock;
+
+	/* initialize the queue */
+	error = vb2_queue_init(&sur40->queue);
+	if (error)
+		goto err_unreg_v4l2;
+
+	sur40->alloc_ctx = vb2_dma_sg_init_ctx(sur40->dev);
+	if (IS_ERR(sur40->alloc_ctx)) {
+		dev_err(sur40->dev, "Can't allocate buffer context");
+		goto err_unreg_v4l2;
+	}
+
+	sur40->vdev = sur40_video_device;
+	sur40->vdev.v4l2_dev = &sur40->v4l2;
+	sur40->vdev.lock = &sur40->lock;
+	sur40->vdev.queue = &sur40->queue;
+	video_set_drvdata(&sur40->vdev, sur40);
+
+	error = video_register_device(&sur40->vdev, VFL_TYPE_GRABBER, -1);
+	if (error) {
+		dev_err(&interface->dev,
+			"Unable to register video subdevice.");
+		goto err_unreg_video;
+	}
+
+	/* we can register the device now, as it is ready */
+	usb_set_intfdata(interface, sur40);
+	dev_dbg(&interface->dev, "%s is now attached\n", DRIVER_DESC);
+
+	return 0;
+
+err_unreg_video:
+	video_unregister_device(&sur40->vdev);
+err_unreg_v4l2:
+	v4l2_device_unregister(&sur40->v4l2);
+err_free_buffer:
+	kfree(sur40->bulk_in_buffer);
+err_free_polldev:
+	input_free_polled_device(sur40->input);
+err_free_dev:
+	kfree(sur40);
+
+	return error;
+}
+
+/* Unregister device & clean up. */
+static void sur40_disconnect(struct usb_interface *interface)
+{
+	struct sur40_state *sur40 = usb_get_intfdata(interface);
+
+	video_unregister_device(&sur40->vdev);
+	v4l2_device_unregister(&sur40->v4l2);
+	vb2_dma_sg_cleanup_ctx(sur40->alloc_ctx);
+
+	input_unregister_polled_device(sur40->input);
+	input_free_polled_device(sur40->input);
+	kfree(sur40->bulk_in_buffer);
+	kfree(sur40);
+
+	usb_set_intfdata(interface, NULL);
+	dev_dbg(&interface->dev, "%s is now disconnected\n", DRIVER_DESC);
+}
+
+/*
+ * Setup the constraints of the queue: besides setting the number of planes
+ * per buffer and the size and allocation context of each plane, it also
+ * checks if sufficient buffers have been allocated. Usually 3 is a good
+ * minimum number: many DMA engines need a minimum of 2 buffers in the
+ * queue and you need to have another available for userspace processing.
+ */
+static int sur40_queue_setup(struct vb2_queue *q, const struct v4l2_format *fmt,
+		       unsigned int *nbuffers, unsigned int *nplanes,
+		       unsigned int sizes[], void *alloc_ctxs[])
+{
+	struct sur40_state *sur40 = vb2_get_drv_priv(q);
+
+	if (q->num_buffers + *nbuffers < 3)
+		*nbuffers = 3 - q->num_buffers;
+
+	if (fmt && fmt->fmt.pix.sizeimage < sur40_video_format.sizeimage)
+		return -EINVAL;
+
+	*nplanes = 1;
+	sizes[0] = fmt ? fmt->fmt.pix.sizeimage : sur40_video_format.sizeimage;
+	alloc_ctxs[0] = sur40->alloc_ctx;
+
+	return 0;
+}
+
+/*
+ * Prepare the buffer for queueing to the DMA engine: check and set the
+ * payload size.
+ */
+static int sur40_buffer_prepare(struct vb2_buffer *vb)
+{
+	struct sur40_state *sur40 = vb2_get_drv_priv(vb->vb2_queue);
+	unsigned long size = sur40_video_format.sizeimage;
+
+	if (vb2_plane_size(vb, 0) < size) {
+		dev_err(&sur40->usbdev->dev, "buffer too small (%lu < %lu)\n",
+			 vb2_plane_size(vb, 0), size);
+		return -EINVAL;
+	}
+
+	vb2_set_plane_payload(vb, 0, size);
+	return 0;
+}
+
+/*
+ * Queue this buffer to the DMA engine.
+ */
+static void sur40_buffer_queue(struct vb2_buffer *vb)
+{
+	struct sur40_state *sur40 = vb2_get_drv_priv(vb->vb2_queue);
+	struct sur40_buffer *buf = (struct sur40_buffer *)vb;
+
+	spin_lock(&sur40->qlock);
+	list_add_tail(&buf->list, &sur40->buf_list);
+	spin_unlock(&sur40->qlock);
+}
+
+static void return_all_buffers(struct sur40_state *sur40,
+			       enum vb2_buffer_state state)
+{
+	struct sur40_buffer *buf, *node;
+
+	spin_lock(&sur40->qlock);
+	list_for_each_entry_safe(buf, node, &sur40->buf_list, list) {
+		vb2_buffer_done(&buf->vb, state);
+		list_del(&buf->list);
+	}
+	spin_unlock(&sur40->qlock);
+}
+
+/*
+ * Start streaming. First check if the minimum number of buffers have been
+ * queued. If not, then return -ENOBUFS and the vb2 framework will call
+ * this function again the next time a buffer has been queued until enough
+ * buffers are available to actually start the DMA engine.
+ */
+static int sur40_start_streaming(struct vb2_queue *vq, unsigned int count)
+{
+	struct sur40_state *sur40 = vb2_get_drv_priv(vq);
+
+	sur40->sequence = 0;
+	return 0;
+}
+
+/*
+ * Stop the DMA engine. Any remaining buffers in the DMA queue are dequeued
+ * and passed on to the vb2 framework marked as STATE_ERROR.
+ */
+static void sur40_stop_streaming(struct vb2_queue *vq)
+{
+	struct sur40_state *sur40 = vb2_get_drv_priv(vq);
+
+	/* Release all active buffers */
+	return_all_buffers(sur40, VB2_BUF_STATE_ERROR);
+}
+
+/* V4L ioctl */
+static int sur40_vidioc_querycap(struct file *file, void *priv,
+				 struct v4l2_capability *cap)
+{
+	struct sur40_state *sur40 = video_drvdata(file);
+
+	strlcpy(cap->driver, DRIVER_SHORT, sizeof(cap->driver));
+	strlcpy(cap->card, DRIVER_LONG, sizeof(cap->card));
+	usb_make_path(sur40->usbdev, cap->bus_info, sizeof(cap->bus_info));
+	cap->device_caps = V4L2_CAP_VIDEO_CAPTURE |
+		V4L2_CAP_READWRITE |
+		V4L2_CAP_STREAMING;
+	cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
+	return 0;
+}
+
+static int sur40_vidioc_enum_input(struct file *file, void *priv,
+				   struct v4l2_input *i)
+{
+	if (i->index != 0)
+		return -EINVAL;
+	i->type = V4L2_INPUT_TYPE_CAMERA;
+	i->std = V4L2_STD_UNKNOWN;
+	strlcpy(i->name, "In-Cell Sensor", sizeof(i->name));
+	i->capabilities = 0;
+	return 0;
+}
+
+static int sur40_vidioc_s_input(struct file *file, void *priv, unsigned int i)
+{
+	return (i == 0) ? 0 : -EINVAL;
+}
+
+static int sur40_vidioc_g_input(struct file *file, void *priv, unsigned int *i)
+{
+	*i = 0;
+	return 0;
+}
+
+static int sur40_vidioc_fmt(struct file *file, void *priv,
+			    struct v4l2_format *f)
+{
+	f->fmt.pix = sur40_video_format;
+	return 0;
+}
+
+static int sur40_vidioc_enum_fmt(struct file *file, void *priv,
+				 struct v4l2_fmtdesc *f)
+{
+	if (f->index != 0)
+		return -EINVAL;
+	strlcpy(f->description, "8-bit greyscale", sizeof(f->description));
+	f->pixelformat = V4L2_PIX_FMT_GREY;
+	f->flags = 0;
+	return 0;
+}
+
+static const struct usb_device_id sur40_table[] = {
+	{ USB_DEVICE(ID_MICROSOFT, ID_SUR40) },  /* Samsung SUR40 */
+	{ }                                      /* terminating null entry */
+};
+MODULE_DEVICE_TABLE(usb, sur40_table);
+
+/* V4L2 structures */
+static const struct vb2_ops sur40_queue_ops = {
+	.queue_setup		= sur40_queue_setup,
+	.buf_prepare		= sur40_buffer_prepare,
+	.buf_queue		= sur40_buffer_queue,
+	.start_streaming	= sur40_start_streaming,
+	.stop_streaming		= sur40_stop_streaming,
+	.wait_prepare		= vb2_ops_wait_prepare,
+	.wait_finish		= vb2_ops_wait_finish,
+};
+
+static const struct vb2_queue sur40_queue = {
+	.type = V4L2_BUF_TYPE_VIDEO_CAPTURE,
+	/*
+	 * VB2_USERPTR in currently not enabled: passing a user pointer to
+	 * dma-sg will result in segment sizes that are not a multiple of
+	 * 512 bytes, which is required by the host controller.
+	*/
+	.io_modes = VB2_MMAP | VB2_READ | VB2_DMABUF,
+	.buf_struct_size = sizeof(struct sur40_buffer),
+	.ops = &sur40_queue_ops,
+	.mem_ops = &vb2_dma_sg_memops,
+	.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC,
+	.min_buffers_needed = 3,
+};
+
+static const struct v4l2_file_operations sur40_video_fops = {
+	.owner = THIS_MODULE,
+	.open = v4l2_fh_open,
+	.release = vb2_fop_release,
+	.unlocked_ioctl = video_ioctl2,
+	.read = vb2_fop_read,
+	.mmap = vb2_fop_mmap,
+	.poll = vb2_fop_poll,
+};
+
+static const struct v4l2_ioctl_ops sur40_video_ioctl_ops = {
+
+	.vidioc_querycap	= sur40_vidioc_querycap,
+
+	.vidioc_enum_fmt_vid_cap = sur40_vidioc_enum_fmt,
+	.vidioc_try_fmt_vid_cap	= sur40_vidioc_fmt,
+	.vidioc_s_fmt_vid_cap	= sur40_vidioc_fmt,
+	.vidioc_g_fmt_vid_cap	= sur40_vidioc_fmt,
+
+	.vidioc_enum_input	= sur40_vidioc_enum_input,
+	.vidioc_g_input		= sur40_vidioc_g_input,
+	.vidioc_s_input		= sur40_vidioc_s_input,
+
+	.vidioc_reqbufs		= vb2_ioctl_reqbufs,
+	.vidioc_create_bufs	= vb2_ioctl_create_bufs,
+	.vidioc_querybuf	= vb2_ioctl_querybuf,
+	.vidioc_qbuf		= vb2_ioctl_qbuf,
+	.vidioc_dqbuf		= vb2_ioctl_dqbuf,
+	.vidioc_expbuf		= vb2_ioctl_expbuf,
+
+	.vidioc_streamon	= vb2_ioctl_streamon,
+	.vidioc_streamoff	= vb2_ioctl_streamoff,
+};
+
+static const struct video_device sur40_video_device = {
+	.name = DRIVER_LONG,
+	.fops = &sur40_video_fops,
+	.ioctl_ops = &sur40_video_ioctl_ops,
+	.release = video_device_release_empty,
+};
+
+static const struct v4l2_pix_format sur40_video_format = {
+	.pixelformat = V4L2_PIX_FMT_GREY,
+	.width  = SENSOR_RES_X / 2,
+	.height = SENSOR_RES_Y / 2,
+	.field = V4L2_FIELD_NONE,
+	.colorspace = V4L2_COLORSPACE_SRGB,
+	.bytesperline = SENSOR_RES_X / 2,
+	.sizeimage = (SENSOR_RES_X/2) * (SENSOR_RES_Y/2),
+};
+
+/* USB-specific object needed to register this driver with the USB subsystem. */
+static struct usb_driver sur40_driver = {
+	.name = DRIVER_SHORT,
+	.probe = sur40_probe,
+	.disconnect = sur40_disconnect,
+	.id_table = sur40_table,
+};
+
+module_usb_driver(sur40_driver);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");