1 /*
2  * Surface2.0/SUR40/PixelSense input driver
3  *
4  * Copyright (c) 2014 by Florian 'floe' Echtler <floe@butterbrot.org>
5  *
6  * Derived from the USB Skeleton driver 1.1,
7  * Copyright (c) 2003 Greg Kroah-Hartman (greg@kroah.com)
8  *
9  * and from the Apple USB BCM5974 multitouch driver,
10  * Copyright (c) 2008 Henrik Rydberg (rydberg@euromail.se)
11  *
12  * and from the generic hid-multitouch driver,
13  * Copyright (c) 2010-2012 Stephane Chatty <chatty@enac.fr>
14  *
15  * and from the v4l2-pci-skeleton driver,
16  * Copyright (c) Copyright 2014 Cisco Systems, Inc.
17  *
18  * This program is free software; you can redistribute it and/or
19  * modify it under the terms of the GNU General Public License as
20  * published by the Free Software Foundation; either version 2 of
21  * the License, or (at your option) any later version.
22  */
23 
24 #include <linux/kernel.h>
25 #include <linux/errno.h>
26 #include <linux/delay.h>
27 #include <linux/init.h>
28 #include <linux/slab.h>
29 #include <linux/module.h>
30 #include <linux/completion.h>
31 #include <linux/uaccess.h>
32 #include <linux/usb.h>
33 #include <linux/printk.h>
34 #include <linux/input-polldev.h>
35 #include <linux/input/mt.h>
36 #include <linux/usb/input.h>
37 #include <linux/videodev2.h>
38 #include <media/v4l2-device.h>
39 #include <media/v4l2-dev.h>
40 #include <media/v4l2-ioctl.h>
41 #include <media/videobuf2-dma-sg.h>
42 
43 /* read 512 bytes from endpoint 0x86 -> get header + blobs */
44 struct sur40_header {
45 
46 	__le16 type;       /* always 0x0001 */
47 	__le16 count;      /* count of blobs (if 0: continue prev. packet) */
48 
49 	__le32 packet_id;  /* unique ID for all packets in one frame */
50 
51 	__le32 timestamp;  /* milliseconds (inc. by 16 or 17 each frame) */
52 	__le32 unknown;    /* "epoch?" always 02/03 00 00 00 */
53 
54 } __packed;
55 
56 struct sur40_blob {
57 
58 	__le16 blob_id;
59 
60 	u8 action;         /* 0x02 = enter/exit, 0x03 = update (?) */
61 	u8 unknown;        /* always 0x01 or 0x02 (no idea what this is?) */
62 
63 	__le16 bb_pos_x;   /* upper left corner of bounding box */
64 	__le16 bb_pos_y;
65 
66 	__le16 bb_size_x;  /* size of bounding box */
67 	__le16 bb_size_y;
68 
69 	__le16 pos_x;      /* finger tip position */
70 	__le16 pos_y;
71 
72 	__le16 ctr_x;      /* centroid position */
73 	__le16 ctr_y;
74 
75 	__le16 axis_x;     /* somehow related to major/minor axis, mostly: */
76 	__le16 axis_y;     /* axis_x == bb_size_y && axis_y == bb_size_x */
77 
78 	__le32 angle;      /* orientation in radians relative to x axis -
79 	                      actually an IEEE754 float, don't use in kernel */
80 
81 	__le32 area;       /* size in pixels/pressure (?) */
82 
83 	u8 padding[32];
84 
85 } __packed;
86 
87 /* combined header/blob data */
88 struct sur40_data {
89 	struct sur40_header header;
90 	struct sur40_blob   blobs[];
91 } __packed;
92 
93 /* read 512 bytes from endpoint 0x82 -> get header below
94  * continue reading 16k blocks until header.size bytes read */
95 struct sur40_image_header {
96 	__le32 magic;     /* "SUBF" */
97 	__le32 packet_id;
98 	__le32 size;      /* always 0x0007e900 = 960x540 */
99 	__le32 timestamp; /* milliseconds (increases by 16 or 17 each frame) */
100 	__le32 unknown;   /* "epoch?" always 02/03 00 00 00 */
101 } __packed;
102 
103 /* version information */
104 #define DRIVER_SHORT   "sur40"
105 #define DRIVER_LONG    "Samsung SUR40"
106 #define DRIVER_AUTHOR  "Florian 'floe' Echtler <floe@butterbrot.org>"
107 #define DRIVER_DESC    "Surface2.0/SUR40/PixelSense input driver"
108 
109 /* vendor and device IDs */
110 #define ID_MICROSOFT 0x045e
111 #define ID_SUR40     0x0775
112 
113 /* sensor resolution */
114 #define SENSOR_RES_X 1920
115 #define SENSOR_RES_Y 1080
116 
117 /* touch data endpoint */
118 #define TOUCH_ENDPOINT 0x86
119 
120 /* video data endpoint */
121 #define VIDEO_ENDPOINT 0x82
122 
123 /* video header fields */
124 #define VIDEO_HEADER_MAGIC 0x46425553
125 #define VIDEO_PACKET_SIZE  16384
126 
127 /* polling interval (ms) */
128 #define POLL_INTERVAL 10
129 
130 /* maximum number of contacts FIXME: this is a guess? */
131 #define MAX_CONTACTS 64
132 
133 /* control commands */
134 #define SUR40_GET_VERSION 0xb0 /* 12 bytes string    */
135 #define SUR40_UNKNOWN1    0xb3 /*  5 bytes           */
136 #define SUR40_UNKNOWN2    0xc1 /* 24 bytes           */
137 
138 #define SUR40_GET_STATE   0xc5 /*  4 bytes state (?) */
139 #define SUR40_GET_SENSORS 0xb1 /*  8 bytes sensors   */
140 
141 /* master device state */
142 struct sur40_state {
143 
144 	struct usb_device *usbdev;
145 	struct device *dev;
146 	struct input_polled_dev *input;
147 
148 	struct v4l2_device v4l2;
149 	struct video_device vdev;
150 	struct mutex lock;
151 
152 	struct vb2_queue queue;
153 	struct vb2_alloc_ctx *alloc_ctx;
154 	struct list_head buf_list;
155 	spinlock_t qlock;
156 	int sequence;
157 
158 	struct sur40_data *bulk_in_buffer;
159 	size_t bulk_in_size;
160 	u8 bulk_in_epaddr;
161 
162 	char phys[64];
163 };
164 
165 struct sur40_buffer {
166 	struct vb2_buffer vb;
167 	struct list_head list;
168 };
169 
170 /* forward declarations */
171 static const struct video_device sur40_video_device;
172 static const struct v4l2_pix_format sur40_video_format;
173 static const struct vb2_queue sur40_queue;
174 static void sur40_process_video(struct sur40_state *sur40);
175 
176 /*
177  * Note: an earlier, non-public version of this driver used USB_RECIP_ENDPOINT
178  * here by mistake which is very likely to have corrupted the firmware EEPROM
179  * on two separate SUR40 devices. Thanks to Alan Stern who spotted this bug.
180  * Should you ever run into a similar problem, the background story to this
181  * incident and instructions on how to fix the corrupted EEPROM are available
182  * at https://floe.butterbrot.org/matrix/hacking/surface/brick.html
183 */
184 
185 /* command wrapper */
186 static int sur40_command(struct sur40_state *dev,
187 			 u8 command, u16 index, void *buffer, u16 size)
188 {
189 	return usb_control_msg(dev->usbdev, usb_rcvctrlpipe(dev->usbdev, 0),
190 			       command,
191 			       USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
192 			       0x00, index, buffer, size, 1000);
193 }
194 
195 /* Initialization routine, called from sur40_open */
196 static int sur40_init(struct sur40_state *dev)
197 {
198 	int result;
199 	u8 buffer[24];
200 
201 	/* stupidly replay the original MS driver init sequence */
202 	result = sur40_command(dev, SUR40_GET_VERSION, 0x00, buffer, 12);
203 	if (result < 0)
204 		return result;
205 
206 	result = sur40_command(dev, SUR40_GET_VERSION, 0x01, buffer, 12);
207 	if (result < 0)
208 		return result;
209 
210 	result = sur40_command(dev, SUR40_GET_VERSION, 0x02, buffer, 12);
211 	if (result < 0)
212 		return result;
213 
214 	result = sur40_command(dev, SUR40_UNKNOWN2,    0x00, buffer, 24);
215 	if (result < 0)
216 		return result;
217 
218 	result = sur40_command(dev, SUR40_UNKNOWN1,    0x00, buffer,  5);
219 	if (result < 0)
220 		return result;
221 
222 	result = sur40_command(dev, SUR40_GET_VERSION, 0x03, buffer, 12);
223 
224 	/*
225 	 * Discard the result buffer - no known data inside except
226 	 * some version strings, maybe extract these sometime...
227 	 */
228 
229 	return result;
230 }
231 
232 /*
233  * Callback routines from input_polled_dev
234  */
235 
236 /* Enable the device, polling will now start. */
237 static void sur40_open(struct input_polled_dev *polldev)
238 {
239 	struct sur40_state *sur40 = polldev->private;
240 
241 	dev_dbg(sur40->dev, "open\n");
242 	sur40_init(sur40);
243 }
244 
245 /* Disable device, polling has stopped. */
246 static void sur40_close(struct input_polled_dev *polldev)
247 {
248 	struct sur40_state *sur40 = polldev->private;
249 
250 	dev_dbg(sur40->dev, "close\n");
251 	/*
252 	 * There is no known way to stop the device, so we simply
253 	 * stop polling.
254 	 */
255 }
256 
257 /*
258  * This function is called when a whole contact has been processed,
259  * so that it can assign it to a slot and store the data there.
260  */
261 static void sur40_report_blob(struct sur40_blob *blob, struct input_dev *input)
262 {
263 	int wide, major, minor;
264 
265 	int bb_size_x = le16_to_cpu(blob->bb_size_x);
266 	int bb_size_y = le16_to_cpu(blob->bb_size_y);
267 
268 	int pos_x = le16_to_cpu(blob->pos_x);
269 	int pos_y = le16_to_cpu(blob->pos_y);
270 
271 	int ctr_x = le16_to_cpu(blob->ctr_x);
272 	int ctr_y = le16_to_cpu(blob->ctr_y);
273 
274 	int slotnum = input_mt_get_slot_by_key(input, blob->blob_id);
275 	if (slotnum < 0 || slotnum >= MAX_CONTACTS)
276 		return;
277 
278 	input_mt_slot(input, slotnum);
279 	input_mt_report_slot_state(input, MT_TOOL_FINGER, 1);
280 	wide = (bb_size_x > bb_size_y);
281 	major = max(bb_size_x, bb_size_y);
282 	minor = min(bb_size_x, bb_size_y);
283 
284 	input_report_abs(input, ABS_MT_POSITION_X, pos_x);
285 	input_report_abs(input, ABS_MT_POSITION_Y, pos_y);
286 	input_report_abs(input, ABS_MT_TOOL_X, ctr_x);
287 	input_report_abs(input, ABS_MT_TOOL_Y, ctr_y);
288 
289 	/* TODO: use a better orientation measure */
290 	input_report_abs(input, ABS_MT_ORIENTATION, wide);
291 	input_report_abs(input, ABS_MT_TOUCH_MAJOR, major);
292 	input_report_abs(input, ABS_MT_TOUCH_MINOR, minor);
293 }
294 
295 /* core function: poll for new input data */
296 static void sur40_poll(struct input_polled_dev *polldev)
297 {
298 	struct sur40_state *sur40 = polldev->private;
299 	struct input_dev *input = polldev->input;
300 	int result, bulk_read, need_blobs, packet_blobs, i;
301 	u32 uninitialized_var(packet_id);
302 
303 	struct sur40_header *header = &sur40->bulk_in_buffer->header;
304 	struct sur40_blob *inblob = &sur40->bulk_in_buffer->blobs[0];
305 
306 	dev_dbg(sur40->dev, "poll\n");
307 
308 	need_blobs = -1;
309 
310 	do {
311 
312 		/* perform a blocking bulk read to get data from the device */
313 		result = usb_bulk_msg(sur40->usbdev,
314 			usb_rcvbulkpipe(sur40->usbdev, sur40->bulk_in_epaddr),
315 			sur40->bulk_in_buffer, sur40->bulk_in_size,
316 			&bulk_read, 1000);
317 
318 		dev_dbg(sur40->dev, "received %d bytes\n", bulk_read);
319 
320 		if (result < 0) {
321 			dev_err(sur40->dev, "error in usb_bulk_read\n");
322 			return;
323 		}
324 
325 		result = bulk_read - sizeof(struct sur40_header);
326 
327 		if (result % sizeof(struct sur40_blob) != 0) {
328 			dev_err(sur40->dev, "transfer size mismatch\n");
329 			return;
330 		}
331 
332 		/* first packet? */
333 		if (need_blobs == -1) {
334 			need_blobs = le16_to_cpu(header->count);
335 			dev_dbg(sur40->dev, "need %d blobs\n", need_blobs);
336 			packet_id = le32_to_cpu(header->packet_id);
337 		}
338 
339 		/*
340 		 * Sanity check. when video data is also being retrieved, the
341 		 * packet ID will usually increase in the middle of a series
342 		 * instead of at the end.
343 		 */
344 		if (packet_id != header->packet_id)
345 			dev_warn(sur40->dev, "packet ID mismatch\n");
346 
347 		packet_blobs = result / sizeof(struct sur40_blob);
348 		dev_dbg(sur40->dev, "received %d blobs\n", packet_blobs);
349 
350 		/* packets always contain at least 4 blobs, even if empty */
351 		if (packet_blobs > need_blobs)
352 			packet_blobs = need_blobs;
353 
354 		for (i = 0; i < packet_blobs; i++) {
355 			need_blobs--;
356 			dev_dbg(sur40->dev, "processing blob\n");
357 			sur40_report_blob(&(inblob[i]), input);
358 		}
359 
360 	} while (need_blobs > 0);
361 
362 	input_mt_sync_frame(input);
363 	input_sync(input);
364 
365 	sur40_process_video(sur40);
366 }
367 
368 /* deal with video data */
369 static void sur40_process_video(struct sur40_state *sur40)
370 {
371 
372 	struct sur40_image_header *img = (void *)(sur40->bulk_in_buffer);
373 	struct sur40_buffer *new_buf;
374 	struct usb_sg_request sgr;
375 	struct sg_table *sgt;
376 	int result, bulk_read;
377 
378 	if (!vb2_start_streaming_called(&sur40->queue))
379 		return;
380 
381 	/* get a new buffer from the list */
382 	spin_lock(&sur40->qlock);
383 	if (list_empty(&sur40->buf_list)) {
384 		dev_dbg(sur40->dev, "buffer queue empty\n");
385 		spin_unlock(&sur40->qlock);
386 		return;
387 	}
388 	new_buf = list_entry(sur40->buf_list.next, struct sur40_buffer, list);
389 	list_del(&new_buf->list);
390 	spin_unlock(&sur40->qlock);
391 
392 	/* retrieve data via bulk read */
393 	result = usb_bulk_msg(sur40->usbdev,
394 			usb_rcvbulkpipe(sur40->usbdev, VIDEO_ENDPOINT),
395 			sur40->bulk_in_buffer, sur40->bulk_in_size,
396 			&bulk_read, 1000);
397 
398 	if (result < 0) {
399 		dev_err(sur40->dev, "error in usb_bulk_read\n");
400 		goto err_poll;
401 	}
402 
403 	if (bulk_read != sizeof(struct sur40_image_header)) {
404 		dev_err(sur40->dev, "received %d bytes (%zd expected)\n",
405 			bulk_read, sizeof(struct sur40_image_header));
406 		goto err_poll;
407 	}
408 
409 	if (le32_to_cpu(img->magic) != VIDEO_HEADER_MAGIC) {
410 		dev_err(sur40->dev, "image magic mismatch\n");
411 		goto err_poll;
412 	}
413 
414 	if (le32_to_cpu(img->size) != sur40_video_format.sizeimage) {
415 		dev_err(sur40->dev, "image size mismatch\n");
416 		goto err_poll;
417 	}
418 
419 	sgt = vb2_dma_sg_plane_desc(&new_buf->vb, 0);
420 
421 	result = usb_sg_init(&sgr, sur40->usbdev,
422 		usb_rcvbulkpipe(sur40->usbdev, VIDEO_ENDPOINT), 0,
423 		sgt->sgl, sgt->nents, sur40_video_format.sizeimage, 0);
424 	if (result < 0) {
425 		dev_err(sur40->dev, "error %d in usb_sg_init\n", result);
426 		goto err_poll;
427 	}
428 
429 	usb_sg_wait(&sgr);
430 	if (sgr.status < 0) {
431 		dev_err(sur40->dev, "error %d in usb_sg_wait\n", sgr.status);
432 		goto err_poll;
433 	}
434 
435 	/* mark as finished */
436 	v4l2_get_timestamp(&new_buf->vb.v4l2_buf.timestamp);
437 	new_buf->vb.v4l2_buf.sequence = sur40->sequence++;
438 	new_buf->vb.v4l2_buf.field = V4L2_FIELD_NONE;
439 	vb2_buffer_done(&new_buf->vb, VB2_BUF_STATE_DONE);
440 	return;
441 
442 err_poll:
443 	vb2_buffer_done(&new_buf->vb, VB2_BUF_STATE_ERROR);
444 }
445 
446 /* Initialize input device parameters. */
447 static void sur40_input_setup(struct input_dev *input_dev)
448 {
449 	__set_bit(EV_KEY, input_dev->evbit);
450 	__set_bit(EV_ABS, input_dev->evbit);
451 
452 	input_set_abs_params(input_dev, ABS_MT_POSITION_X,
453 			     0, SENSOR_RES_X, 0, 0);
454 	input_set_abs_params(input_dev, ABS_MT_POSITION_Y,
455 			     0, SENSOR_RES_Y, 0, 0);
456 
457 	input_set_abs_params(input_dev, ABS_MT_TOOL_X,
458 			     0, SENSOR_RES_X, 0, 0);
459 	input_set_abs_params(input_dev, ABS_MT_TOOL_Y,
460 			     0, SENSOR_RES_Y, 0, 0);
461 
462 	/* max value unknown, but major/minor axis
463 	 * can never be larger than screen */
464 	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR,
465 			     0, SENSOR_RES_X, 0, 0);
466 	input_set_abs_params(input_dev, ABS_MT_TOUCH_MINOR,
467 			     0, SENSOR_RES_Y, 0, 0);
468 
469 	input_set_abs_params(input_dev, ABS_MT_ORIENTATION, 0, 1, 0, 0);
470 
471 	input_mt_init_slots(input_dev, MAX_CONTACTS,
472 			    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
473 }
474 
475 /* Check candidate USB interface. */
476 static int sur40_probe(struct usb_interface *interface,
477 		       const struct usb_device_id *id)
478 {
479 	struct usb_device *usbdev = interface_to_usbdev(interface);
480 	struct sur40_state *sur40;
481 	struct usb_host_interface *iface_desc;
482 	struct usb_endpoint_descriptor *endpoint;
483 	struct input_polled_dev *poll_dev;
484 	int error;
485 
486 	/* Check if we really have the right interface. */
487 	iface_desc = &interface->altsetting[0];
488 	if (iface_desc->desc.bInterfaceClass != 0xFF)
489 		return -ENODEV;
490 
491 	/* Use endpoint #4 (0x86). */
492 	endpoint = &iface_desc->endpoint[4].desc;
493 	if (endpoint->bEndpointAddress != TOUCH_ENDPOINT)
494 		return -ENODEV;
495 
496 	/* Allocate memory for our device state and initialize it. */
497 	sur40 = kzalloc(sizeof(struct sur40_state), GFP_KERNEL);
498 	if (!sur40)
499 		return -ENOMEM;
500 
501 	poll_dev = input_allocate_polled_device();
502 	if (!poll_dev) {
503 		error = -ENOMEM;
504 		goto err_free_dev;
505 	}
506 
507 	/* initialize locks/lists */
508 	INIT_LIST_HEAD(&sur40->buf_list);
509 	spin_lock_init(&sur40->qlock);
510 	mutex_init(&sur40->lock);
511 
512 	/* Set up polled input device control structure */
513 	poll_dev->private = sur40;
514 	poll_dev->poll_interval = POLL_INTERVAL;
515 	poll_dev->open = sur40_open;
516 	poll_dev->poll = sur40_poll;
517 	poll_dev->close = sur40_close;
518 
519 	/* Set up regular input device structure */
520 	sur40_input_setup(poll_dev->input);
521 
522 	poll_dev->input->name = DRIVER_LONG;
523 	usb_to_input_id(usbdev, &poll_dev->input->id);
524 	usb_make_path(usbdev, sur40->phys, sizeof(sur40->phys));
525 	strlcat(sur40->phys, "/input0", sizeof(sur40->phys));
526 	poll_dev->input->phys = sur40->phys;
527 	poll_dev->input->dev.parent = &interface->dev;
528 
529 	sur40->usbdev = usbdev;
530 	sur40->dev = &interface->dev;
531 	sur40->input = poll_dev;
532 
533 	/* use the bulk-in endpoint tested above */
534 	sur40->bulk_in_size = usb_endpoint_maxp(endpoint);
535 	sur40->bulk_in_epaddr = endpoint->bEndpointAddress;
536 	sur40->bulk_in_buffer = kmalloc(sur40->bulk_in_size, GFP_KERNEL);
537 	if (!sur40->bulk_in_buffer) {
538 		dev_err(&interface->dev, "Unable to allocate input buffer.");
539 		error = -ENOMEM;
540 		goto err_free_polldev;
541 	}
542 
543 	/* register the polled input device */
544 	error = input_register_polled_device(poll_dev);
545 	if (error) {
546 		dev_err(&interface->dev,
547 			"Unable to register polled input device.");
548 		goto err_free_buffer;
549 	}
550 
551 	/* register the video master device */
552 	snprintf(sur40->v4l2.name, sizeof(sur40->v4l2.name), "%s", DRIVER_LONG);
553 	error = v4l2_device_register(sur40->dev, &sur40->v4l2);
554 	if (error) {
555 		dev_err(&interface->dev,
556 			"Unable to register video master device.");
557 		goto err_unreg_v4l2;
558 	}
559 
560 	/* initialize the lock and subdevice */
561 	sur40->queue = sur40_queue;
562 	sur40->queue.drv_priv = sur40;
563 	sur40->queue.lock = &sur40->lock;
564 
565 	/* initialize the queue */
566 	error = vb2_queue_init(&sur40->queue);
567 	if (error)
568 		goto err_unreg_v4l2;
569 
570 	sur40->alloc_ctx = vb2_dma_sg_init_ctx(sur40->dev);
571 	if (IS_ERR(sur40->alloc_ctx)) {
572 		dev_err(sur40->dev, "Can't allocate buffer context");
573 		goto err_unreg_v4l2;
574 	}
575 
576 	sur40->vdev = sur40_video_device;
577 	sur40->vdev.v4l2_dev = &sur40->v4l2;
578 	sur40->vdev.lock = &sur40->lock;
579 	sur40->vdev.queue = &sur40->queue;
580 	video_set_drvdata(&sur40->vdev, sur40);
581 
582 	error = video_register_device(&sur40->vdev, VFL_TYPE_GRABBER, -1);
583 	if (error) {
584 		dev_err(&interface->dev,
585 			"Unable to register video subdevice.");
586 		goto err_unreg_video;
587 	}
588 
589 	/* we can register the device now, as it is ready */
590 	usb_set_intfdata(interface, sur40);
591 	dev_dbg(&interface->dev, "%s is now attached\n", DRIVER_DESC);
592 
593 	return 0;
594 
595 err_unreg_video:
596 	video_unregister_device(&sur40->vdev);
597 err_unreg_v4l2:
598 	v4l2_device_unregister(&sur40->v4l2);
599 err_free_buffer:
600 	kfree(sur40->bulk_in_buffer);
601 err_free_polldev:
602 	input_free_polled_device(sur40->input);
603 err_free_dev:
604 	kfree(sur40);
605 
606 	return error;
607 }
608 
609 /* Unregister device & clean up. */
610 static void sur40_disconnect(struct usb_interface *interface)
611 {
612 	struct sur40_state *sur40 = usb_get_intfdata(interface);
613 
614 	video_unregister_device(&sur40->vdev);
615 	v4l2_device_unregister(&sur40->v4l2);
616 	vb2_dma_sg_cleanup_ctx(sur40->alloc_ctx);
617 
618 	input_unregister_polled_device(sur40->input);
619 	input_free_polled_device(sur40->input);
620 	kfree(sur40->bulk_in_buffer);
621 	kfree(sur40);
622 
623 	usb_set_intfdata(interface, NULL);
624 	dev_dbg(&interface->dev, "%s is now disconnected\n", DRIVER_DESC);
625 }
626 
627 /*
628  * Setup the constraints of the queue: besides setting the number of planes
629  * per buffer and the size and allocation context of each plane, it also
630  * checks if sufficient buffers have been allocated. Usually 3 is a good
631  * minimum number: many DMA engines need a minimum of 2 buffers in the
632  * queue and you need to have another available for userspace processing.
633  */
634 static int sur40_queue_setup(struct vb2_queue *q, const struct v4l2_format *fmt,
635 		       unsigned int *nbuffers, unsigned int *nplanes,
636 		       unsigned int sizes[], void *alloc_ctxs[])
637 {
638 	struct sur40_state *sur40 = vb2_get_drv_priv(q);
639 
640 	if (q->num_buffers + *nbuffers < 3)
641 		*nbuffers = 3 - q->num_buffers;
642 
643 	if (fmt && fmt->fmt.pix.sizeimage < sur40_video_format.sizeimage)
644 		return -EINVAL;
645 
646 	*nplanes = 1;
647 	sizes[0] = fmt ? fmt->fmt.pix.sizeimage : sur40_video_format.sizeimage;
648 	alloc_ctxs[0] = sur40->alloc_ctx;
649 
650 	return 0;
651 }
652 
653 /*
654  * Prepare the buffer for queueing to the DMA engine: check and set the
655  * payload size.
656  */
657 static int sur40_buffer_prepare(struct vb2_buffer *vb)
658 {
659 	struct sur40_state *sur40 = vb2_get_drv_priv(vb->vb2_queue);
660 	unsigned long size = sur40_video_format.sizeimage;
661 
662 	if (vb2_plane_size(vb, 0) < size) {
663 		dev_err(&sur40->usbdev->dev, "buffer too small (%lu < %lu)\n",
664 			 vb2_plane_size(vb, 0), size);
665 		return -EINVAL;
666 	}
667 
668 	vb2_set_plane_payload(vb, 0, size);
669 	return 0;
670 }
671 
672 /*
673  * Queue this buffer to the DMA engine.
674  */
675 static void sur40_buffer_queue(struct vb2_buffer *vb)
676 {
677 	struct sur40_state *sur40 = vb2_get_drv_priv(vb->vb2_queue);
678 	struct sur40_buffer *buf = (struct sur40_buffer *)vb;
679 
680 	spin_lock(&sur40->qlock);
681 	list_add_tail(&buf->list, &sur40->buf_list);
682 	spin_unlock(&sur40->qlock);
683 }
684 
685 static void return_all_buffers(struct sur40_state *sur40,
686 			       enum vb2_buffer_state state)
687 {
688 	struct sur40_buffer *buf, *node;
689 
690 	spin_lock(&sur40->qlock);
691 	list_for_each_entry_safe(buf, node, &sur40->buf_list, list) {
692 		vb2_buffer_done(&buf->vb, state);
693 		list_del(&buf->list);
694 	}
695 	spin_unlock(&sur40->qlock);
696 }
697 
698 /*
699  * Start streaming. First check if the minimum number of buffers have been
700  * queued. If not, then return -ENOBUFS and the vb2 framework will call
701  * this function again the next time a buffer has been queued until enough
702  * buffers are available to actually start the DMA engine.
703  */
704 static int sur40_start_streaming(struct vb2_queue *vq, unsigned int count)
705 {
706 	struct sur40_state *sur40 = vb2_get_drv_priv(vq);
707 
708 	sur40->sequence = 0;
709 	return 0;
710 }
711 
712 /*
713  * Stop the DMA engine. Any remaining buffers in the DMA queue are dequeued
714  * and passed on to the vb2 framework marked as STATE_ERROR.
715  */
716 static void sur40_stop_streaming(struct vb2_queue *vq)
717 {
718 	struct sur40_state *sur40 = vb2_get_drv_priv(vq);
719 
720 	/* Release all active buffers */
721 	return_all_buffers(sur40, VB2_BUF_STATE_ERROR);
722 }
723 
724 /* V4L ioctl */
725 static int sur40_vidioc_querycap(struct file *file, void *priv,
726 				 struct v4l2_capability *cap)
727 {
728 	struct sur40_state *sur40 = video_drvdata(file);
729 
730 	strlcpy(cap->driver, DRIVER_SHORT, sizeof(cap->driver));
731 	strlcpy(cap->card, DRIVER_LONG, sizeof(cap->card));
732 	usb_make_path(sur40->usbdev, cap->bus_info, sizeof(cap->bus_info));
733 	cap->device_caps = V4L2_CAP_VIDEO_CAPTURE |
734 		V4L2_CAP_READWRITE |
735 		V4L2_CAP_STREAMING;
736 	cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
737 	return 0;
738 }
739 
740 static int sur40_vidioc_enum_input(struct file *file, void *priv,
741 				   struct v4l2_input *i)
742 {
743 	if (i->index != 0)
744 		return -EINVAL;
745 	i->type = V4L2_INPUT_TYPE_CAMERA;
746 	i->std = V4L2_STD_UNKNOWN;
747 	strlcpy(i->name, "In-Cell Sensor", sizeof(i->name));
748 	i->capabilities = 0;
749 	return 0;
750 }
751 
752 static int sur40_vidioc_s_input(struct file *file, void *priv, unsigned int i)
753 {
754 	return (i == 0) ? 0 : -EINVAL;
755 }
756 
757 static int sur40_vidioc_g_input(struct file *file, void *priv, unsigned int *i)
758 {
759 	*i = 0;
760 	return 0;
761 }
762 
763 static int sur40_vidioc_fmt(struct file *file, void *priv,
764 			    struct v4l2_format *f)
765 {
766 	f->fmt.pix = sur40_video_format;
767 	return 0;
768 }
769 
770 static int sur40_vidioc_enum_fmt(struct file *file, void *priv,
771 				 struct v4l2_fmtdesc *f)
772 {
773 	if (f->index != 0)
774 		return -EINVAL;
775 	strlcpy(f->description, "8-bit greyscale", sizeof(f->description));
776 	f->pixelformat = V4L2_PIX_FMT_GREY;
777 	f->flags = 0;
778 	return 0;
779 }
780 
781 static const struct usb_device_id sur40_table[] = {
782 	{ USB_DEVICE(ID_MICROSOFT, ID_SUR40) },  /* Samsung SUR40 */
783 	{ }                                      /* terminating null entry */
784 };
785 MODULE_DEVICE_TABLE(usb, sur40_table);
786 
787 /* V4L2 structures */
788 static const struct vb2_ops sur40_queue_ops = {
789 	.queue_setup		= sur40_queue_setup,
790 	.buf_prepare		= sur40_buffer_prepare,
791 	.buf_queue		= sur40_buffer_queue,
792 	.start_streaming	= sur40_start_streaming,
793 	.stop_streaming		= sur40_stop_streaming,
794 	.wait_prepare		= vb2_ops_wait_prepare,
795 	.wait_finish		= vb2_ops_wait_finish,
796 };
797 
798 static const struct vb2_queue sur40_queue = {
799 	.type = V4L2_BUF_TYPE_VIDEO_CAPTURE,
800 	/*
801 	 * VB2_USERPTR in currently not enabled: passing a user pointer to
802 	 * dma-sg will result in segment sizes that are not a multiple of
803 	 * 512 bytes, which is required by the host controller.
804 	*/
805 	.io_modes = VB2_MMAP | VB2_READ | VB2_DMABUF,
806 	.buf_struct_size = sizeof(struct sur40_buffer),
807 	.ops = &sur40_queue_ops,
808 	.mem_ops = &vb2_dma_sg_memops,
809 	.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC,
810 	.min_buffers_needed = 3,
811 };
812 
813 static const struct v4l2_file_operations sur40_video_fops = {
814 	.owner = THIS_MODULE,
815 	.open = v4l2_fh_open,
816 	.release = vb2_fop_release,
817 	.unlocked_ioctl = video_ioctl2,
818 	.read = vb2_fop_read,
819 	.mmap = vb2_fop_mmap,
820 	.poll = vb2_fop_poll,
821 };
822 
823 static const struct v4l2_ioctl_ops sur40_video_ioctl_ops = {
824 
825 	.vidioc_querycap	= sur40_vidioc_querycap,
826 
827 	.vidioc_enum_fmt_vid_cap = sur40_vidioc_enum_fmt,
828 	.vidioc_try_fmt_vid_cap	= sur40_vidioc_fmt,
829 	.vidioc_s_fmt_vid_cap	= sur40_vidioc_fmt,
830 	.vidioc_g_fmt_vid_cap	= sur40_vidioc_fmt,
831 
832 	.vidioc_enum_input	= sur40_vidioc_enum_input,
833 	.vidioc_g_input		= sur40_vidioc_g_input,
834 	.vidioc_s_input		= sur40_vidioc_s_input,
835 
836 	.vidioc_reqbufs		= vb2_ioctl_reqbufs,
837 	.vidioc_create_bufs	= vb2_ioctl_create_bufs,
838 	.vidioc_querybuf	= vb2_ioctl_querybuf,
839 	.vidioc_qbuf		= vb2_ioctl_qbuf,
840 	.vidioc_dqbuf		= vb2_ioctl_dqbuf,
841 	.vidioc_expbuf		= vb2_ioctl_expbuf,
842 
843 	.vidioc_streamon	= vb2_ioctl_streamon,
844 	.vidioc_streamoff	= vb2_ioctl_streamoff,
845 };
846 
847 static const struct video_device sur40_video_device = {
848 	.name = DRIVER_LONG,
849 	.fops = &sur40_video_fops,
850 	.ioctl_ops = &sur40_video_ioctl_ops,
851 	.release = video_device_release_empty,
852 };
853 
854 static const struct v4l2_pix_format sur40_video_format = {
855 	.pixelformat = V4L2_PIX_FMT_GREY,
856 	.width  = SENSOR_RES_X / 2,
857 	.height = SENSOR_RES_Y / 2,
858 	.field = V4L2_FIELD_NONE,
859 	.colorspace = V4L2_COLORSPACE_SRGB,
860 	.bytesperline = SENSOR_RES_X / 2,
861 	.sizeimage = (SENSOR_RES_X/2) * (SENSOR_RES_Y/2),
862 };
863 
864 /* USB-specific object needed to register this driver with the USB subsystem. */
865 static struct usb_driver sur40_driver = {
866 	.name = DRIVER_SHORT,
867 	.probe = sur40_probe,
868 	.disconnect = sur40_disconnect,
869 	.id_table = sur40_table,
870 };
871 
872 module_usb_driver(sur40_driver);
873 
874 MODULE_AUTHOR(DRIVER_AUTHOR);
875 MODULE_DESCRIPTION(DRIVER_DESC);
876 MODULE_LICENSE("GPL");
877