xref: /openbmc/linux/drivers/video/fbdev/udlfb.c (revision e9b7b8b3)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * udlfb.c -- Framebuffer driver for DisplayLink USB controller
4  *
5  * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
6  * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
7  * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
8  *
9  * Layout is based on skeletonfb by James Simmons and Geert Uytterhoeven,
10  * usb-skeleton by GregKH.
11  *
12  * Device-specific portions based on information from Displaylink, with work
13  * from Florian Echtler, Henrik Bjerregaard Pedersen, and others.
14  */
15 
16 #include <linux/module.h>
17 #include <linux/kernel.h>
18 #include <linux/init.h>
19 #include <linux/usb.h>
20 #include <linux/uaccess.h>
21 #include <linux/mm.h>
22 #include <linux/fb.h>
23 #include <linux/vmalloc.h>
24 #include <linux/slab.h>
25 #include <linux/delay.h>
26 #include <asm/unaligned.h>
27 #include <video/udlfb.h>
28 #include "edid.h"
29 
30 #define OUT_EP_NUM	1	/* The endpoint number we will use */
31 
32 static const struct fb_fix_screeninfo dlfb_fix = {
33 	.id =           "udlfb",
34 	.type =         FB_TYPE_PACKED_PIXELS,
35 	.visual =       FB_VISUAL_TRUECOLOR,
36 	.xpanstep =     0,
37 	.ypanstep =     0,
38 	.ywrapstep =    0,
39 	.accel =        FB_ACCEL_NONE,
40 };
41 
42 static const u32 udlfb_info_flags = FBINFO_READS_FAST |
43 		FBINFO_VIRTFB |
44 		FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_FILLRECT |
45 		FBINFO_HWACCEL_COPYAREA | FBINFO_MISC_ALWAYS_SETPAR;
46 
47 /*
48  * There are many DisplayLink-based graphics products, all with unique PIDs.
49  * So we match on DisplayLink's VID + Vendor-Defined Interface Class (0xff)
50  * We also require a match on SubClass (0x00) and Protocol (0x00),
51  * which is compatible with all known USB 2.0 era graphics chips and firmware,
52  * but allows DisplayLink to increment those for any future incompatible chips
53  */
54 static const struct usb_device_id id_table[] = {
55 	{.idVendor = 0x17e9,
56 	 .bInterfaceClass = 0xff,
57 	 .bInterfaceSubClass = 0x00,
58 	 .bInterfaceProtocol = 0x00,
59 	 .match_flags = USB_DEVICE_ID_MATCH_VENDOR |
60 		USB_DEVICE_ID_MATCH_INT_CLASS |
61 		USB_DEVICE_ID_MATCH_INT_SUBCLASS |
62 		USB_DEVICE_ID_MATCH_INT_PROTOCOL,
63 	},
64 	{},
65 };
66 MODULE_DEVICE_TABLE(usb, id_table);
67 
68 /* module options */
69 static bool console = true; /* Allow fbcon to open framebuffer */
70 static bool fb_defio = true;  /* Detect mmap writes using page faults */
71 static bool shadow = true; /* Optionally disable shadow framebuffer */
72 static int pixel_limit; /* Optionally force a pixel resolution limit */
73 
74 struct dlfb_deferred_free {
75 	struct list_head list;
76 	void *mem;
77 };
78 
79 static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len);
80 
81 /* dlfb keeps a list of urbs for efficient bulk transfers */
82 static void dlfb_urb_completion(struct urb *urb);
83 static struct urb *dlfb_get_urb(struct dlfb_data *dlfb);
84 static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb * urb, size_t len);
85 static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size);
86 static void dlfb_free_urb_list(struct dlfb_data *dlfb);
87 
88 /*
89  * All DisplayLink bulk operations start with 0xAF, followed by specific code
90  * All operations are written to buffers which then later get sent to device
91  */
92 static char *dlfb_set_register(char *buf, u8 reg, u8 val)
93 {
94 	*buf++ = 0xAF;
95 	*buf++ = 0x20;
96 	*buf++ = reg;
97 	*buf++ = val;
98 	return buf;
99 }
100 
101 static char *dlfb_vidreg_lock(char *buf)
102 {
103 	return dlfb_set_register(buf, 0xFF, 0x00);
104 }
105 
106 static char *dlfb_vidreg_unlock(char *buf)
107 {
108 	return dlfb_set_register(buf, 0xFF, 0xFF);
109 }
110 
111 /*
112  * Map FB_BLANK_* to DisplayLink register
113  * DLReg FB_BLANK_*
114  * ----- -----------------------------
115  *  0x00 FB_BLANK_UNBLANK (0)
116  *  0x01 FB_BLANK (1)
117  *  0x03 FB_BLANK_VSYNC_SUSPEND (2)
118  *  0x05 FB_BLANK_HSYNC_SUSPEND (3)
119  *  0x07 FB_BLANK_POWERDOWN (4) Note: requires modeset to come back
120  */
121 static char *dlfb_blanking(char *buf, int fb_blank)
122 {
123 	u8 reg;
124 
125 	switch (fb_blank) {
126 	case FB_BLANK_POWERDOWN:
127 		reg = 0x07;
128 		break;
129 	case FB_BLANK_HSYNC_SUSPEND:
130 		reg = 0x05;
131 		break;
132 	case FB_BLANK_VSYNC_SUSPEND:
133 		reg = 0x03;
134 		break;
135 	case FB_BLANK_NORMAL:
136 		reg = 0x01;
137 		break;
138 	default:
139 		reg = 0x00;
140 	}
141 
142 	buf = dlfb_set_register(buf, 0x1F, reg);
143 
144 	return buf;
145 }
146 
147 static char *dlfb_set_color_depth(char *buf, u8 selection)
148 {
149 	return dlfb_set_register(buf, 0x00, selection);
150 }
151 
152 static char *dlfb_set_base16bpp(char *wrptr, u32 base)
153 {
154 	/* the base pointer is 16 bits wide, 0x20 is hi byte. */
155 	wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
156 	wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
157 	return dlfb_set_register(wrptr, 0x22, base);
158 }
159 
160 /*
161  * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
162  * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
163  */
164 static char *dlfb_set_base8bpp(char *wrptr, u32 base)
165 {
166 	wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
167 	wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
168 	return dlfb_set_register(wrptr, 0x28, base);
169 }
170 
171 static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
172 {
173 	wrptr = dlfb_set_register(wrptr, reg, value >> 8);
174 	return dlfb_set_register(wrptr, reg+1, value);
175 }
176 
177 /*
178  * This is kind of weird because the controller takes some
179  * register values in a different byte order than other registers.
180  */
181 static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
182 {
183 	wrptr = dlfb_set_register(wrptr, reg, value);
184 	return dlfb_set_register(wrptr, reg+1, value >> 8);
185 }
186 
187 /*
188  * LFSR is linear feedback shift register. The reason we have this is
189  * because the display controller needs to minimize the clock depth of
190  * various counters used in the display path. So this code reverses the
191  * provided value into the lfsr16 value by counting backwards to get
192  * the value that needs to be set in the hardware comparator to get the
193  * same actual count. This makes sense once you read above a couple of
194  * times and think about it from a hardware perspective.
195  */
196 static u16 dlfb_lfsr16(u16 actual_count)
197 {
198 	u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
199 
200 	while (actual_count--) {
201 		lv =	 ((lv << 1) |
202 			(((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
203 			& 0xFFFF;
204 	}
205 
206 	return (u16) lv;
207 }
208 
209 /*
210  * This does LFSR conversion on the value that is to be written.
211  * See LFSR explanation above for more detail.
212  */
213 static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
214 {
215 	return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
216 }
217 
218 /*
219  * This takes a standard fbdev screeninfo struct and all of its monitor mode
220  * details and converts them into the DisplayLink equivalent register commands.
221  */
222 static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
223 {
224 	u16 xds, yds;
225 	u16 xde, yde;
226 	u16 yec;
227 
228 	/* x display start */
229 	xds = var->left_margin + var->hsync_len;
230 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
231 	/* x display end */
232 	xde = xds + var->xres;
233 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);
234 
235 	/* y display start */
236 	yds = var->upper_margin + var->vsync_len;
237 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
238 	/* y display end */
239 	yde = yds + var->yres;
240 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);
241 
242 	/* x end count is active + blanking - 1 */
243 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
244 			xde + var->right_margin - 1);
245 
246 	/* libdlo hardcodes hsync start to 1 */
247 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);
248 
249 	/* hsync end is width of sync pulse + 1 */
250 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);
251 
252 	/* hpixels is active pixels */
253 	wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);
254 
255 	/* yendcount is vertical active + vertical blanking */
256 	yec = var->yres + var->upper_margin + var->lower_margin +
257 			var->vsync_len;
258 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);
259 
260 	/* libdlo hardcodes vsync start to 0 */
261 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);
262 
263 	/* vsync end is width of vsync pulse */
264 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);
265 
266 	/* vpixels is active pixels */
267 	wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);
268 
269 	/* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
270 	wrptr = dlfb_set_register_16be(wrptr, 0x1B,
271 			200*1000*1000/var->pixclock);
272 
273 	return wrptr;
274 }
275 
276 /*
277  * This takes a standard fbdev screeninfo struct that was fetched or prepared
278  * and then generates the appropriate command sequence that then drives the
279  * display controller.
280  */
281 static int dlfb_set_video_mode(struct dlfb_data *dlfb,
282 				struct fb_var_screeninfo *var)
283 {
284 	char *buf;
285 	char *wrptr;
286 	int retval;
287 	int writesize;
288 	struct urb *urb;
289 
290 	if (!atomic_read(&dlfb->usb_active))
291 		return -EPERM;
292 
293 	urb = dlfb_get_urb(dlfb);
294 	if (!urb)
295 		return -ENOMEM;
296 
297 	buf = (char *) urb->transfer_buffer;
298 
299 	/*
300 	* This first section has to do with setting the base address on the
301 	* controller * associated with the display. There are 2 base
302 	* pointers, currently, we only * use the 16 bpp segment.
303 	*/
304 	wrptr = dlfb_vidreg_lock(buf);
305 	wrptr = dlfb_set_color_depth(wrptr, 0x00);
306 	/* set base for 16bpp segment to 0 */
307 	wrptr = dlfb_set_base16bpp(wrptr, 0);
308 	/* set base for 8bpp segment to end of fb */
309 	wrptr = dlfb_set_base8bpp(wrptr, dlfb->info->fix.smem_len);
310 
311 	wrptr = dlfb_set_vid_cmds(wrptr, var);
312 	wrptr = dlfb_blanking(wrptr, FB_BLANK_UNBLANK);
313 	wrptr = dlfb_vidreg_unlock(wrptr);
314 
315 	writesize = wrptr - buf;
316 
317 	retval = dlfb_submit_urb(dlfb, urb, writesize);
318 
319 	dlfb->blank_mode = FB_BLANK_UNBLANK;
320 
321 	return retval;
322 }
323 
324 static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
325 {
326 	unsigned long start = vma->vm_start;
327 	unsigned long size = vma->vm_end - vma->vm_start;
328 	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
329 	unsigned long page, pos;
330 
331 	if (info->fbdefio)
332 		return fb_deferred_io_mmap(info, vma);
333 
334 	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
335 		return -EINVAL;
336 	if (size > info->fix.smem_len)
337 		return -EINVAL;
338 	if (offset > info->fix.smem_len - size)
339 		return -EINVAL;
340 
341 	pos = (unsigned long)info->fix.smem_start + offset;
342 
343 	dev_dbg(info->dev, "mmap() framebuffer addr:%lu size:%lu\n",
344 		pos, size);
345 
346 	while (size > 0) {
347 		page = vmalloc_to_pfn((void *)pos);
348 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
349 			return -EAGAIN;
350 
351 		start += PAGE_SIZE;
352 		pos += PAGE_SIZE;
353 		if (size > PAGE_SIZE)
354 			size -= PAGE_SIZE;
355 		else
356 			size = 0;
357 	}
358 
359 	return 0;
360 }
361 
362 /*
363  * Trims identical data from front and back of line
364  * Sets new front buffer address and width
365  * And returns byte count of identical pixels
366  * Assumes CPU natural alignment (unsigned long)
367  * for back and front buffer ptrs and width
368  */
369 static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
370 {
371 	int j, k;
372 	const unsigned long *back = (const unsigned long *) bback;
373 	const unsigned long *front = (const unsigned long *) *bfront;
374 	const int width = *width_bytes / sizeof(unsigned long);
375 	int identical;
376 	int start = width;
377 	int end = width;
378 
379 	for (j = 0; j < width; j++) {
380 		if (back[j] != front[j]) {
381 			start = j;
382 			break;
383 		}
384 	}
385 
386 	for (k = width - 1; k > j; k--) {
387 		if (back[k] != front[k]) {
388 			end = k+1;
389 			break;
390 		}
391 	}
392 
393 	identical = start + (width - end);
394 	*bfront = (u8 *) &front[start];
395 	*width_bytes = (end - start) * sizeof(unsigned long);
396 
397 	return identical * sizeof(unsigned long);
398 }
399 
400 /*
401  * Render a command stream for an encoded horizontal line segment of pixels.
402  *
403  * A command buffer holds several commands.
404  * It always begins with a fresh command header
405  * (the protocol doesn't require this, but we enforce it to allow
406  * multiple buffers to be potentially encoded and sent in parallel).
407  * A single command encodes one contiguous horizontal line of pixels
408  *
409  * The function relies on the client to do all allocation, so that
410  * rendering can be done directly to output buffers (e.g. USB URBs).
411  * The function fills the supplied command buffer, providing information
412  * on where it left off, so the client may call in again with additional
413  * buffers if the line will take several buffers to complete.
414  *
415  * A single command can transmit a maximum of 256 pixels,
416  * regardless of the compression ratio (protocol design limit).
417  * To the hardware, 0 for a size byte means 256
418  *
419  * Rather than 256 pixel commands which are either rl or raw encoded,
420  * the rlx command simply assumes alternating raw and rl spans within one cmd.
421  * This has a slightly larger header overhead, but produces more even results.
422  * It also processes all data (read and write) in a single pass.
423  * Performance benchmarks of common cases show it having just slightly better
424  * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
425  * But for very rl friendly data, will compress not quite as well.
426  */
427 static void dlfb_compress_hline(
428 	const uint16_t **pixel_start_ptr,
429 	const uint16_t *const pixel_end,
430 	uint32_t *device_address_ptr,
431 	uint8_t **command_buffer_ptr,
432 	const uint8_t *const cmd_buffer_end,
433 	unsigned long back_buffer_offset,
434 	int *ident_ptr)
435 {
436 	const uint16_t *pixel = *pixel_start_ptr;
437 	uint32_t dev_addr  = *device_address_ptr;
438 	uint8_t *cmd = *command_buffer_ptr;
439 
440 	while ((pixel_end > pixel) &&
441 	       (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
442 		uint8_t *raw_pixels_count_byte = NULL;
443 		uint8_t *cmd_pixels_count_byte = NULL;
444 		const uint16_t *raw_pixel_start = NULL;
445 		const uint16_t *cmd_pixel_start, *cmd_pixel_end = NULL;
446 
447 		if (back_buffer_offset &&
448 		    *pixel == *(u16 *)((u8 *)pixel + back_buffer_offset)) {
449 			pixel++;
450 			dev_addr += BPP;
451 			(*ident_ptr)++;
452 			continue;
453 		}
454 
455 		*cmd++ = 0xAF;
456 		*cmd++ = 0x6B;
457 		*cmd++ = dev_addr >> 16;
458 		*cmd++ = dev_addr >> 8;
459 		*cmd++ = dev_addr;
460 
461 		cmd_pixels_count_byte = cmd++; /*  we'll know this later */
462 		cmd_pixel_start = pixel;
463 
464 		raw_pixels_count_byte = cmd++; /*  we'll know this later */
465 		raw_pixel_start = pixel;
466 
467 		cmd_pixel_end = pixel + min3(MAX_CMD_PIXELS + 1UL,
468 					(unsigned long)(pixel_end - pixel),
469 					(unsigned long)(cmd_buffer_end - 1 - cmd) / BPP);
470 
471 		if (back_buffer_offset) {
472 			/* note: the framebuffer may change under us, so we must test for underflow */
473 			while (cmd_pixel_end - 1 > pixel &&
474 			       *(cmd_pixel_end - 1) == *(u16 *)((u8 *)(cmd_pixel_end - 1) + back_buffer_offset))
475 				cmd_pixel_end--;
476 		}
477 
478 		while (pixel < cmd_pixel_end) {
479 			const uint16_t * const repeating_pixel = pixel;
480 			u16 pixel_value = *pixel;
481 
482 			put_unaligned_be16(pixel_value, cmd);
483 			if (back_buffer_offset)
484 				*(u16 *)((u8 *)pixel + back_buffer_offset) = pixel_value;
485 			cmd += 2;
486 			pixel++;
487 
488 			if (unlikely((pixel < cmd_pixel_end) &&
489 				     (*pixel == pixel_value))) {
490 				/* go back and fill in raw pixel count */
491 				*raw_pixels_count_byte = ((repeating_pixel -
492 						raw_pixel_start) + 1) & 0xFF;
493 
494 				do {
495 					if (back_buffer_offset)
496 						*(u16 *)((u8 *)pixel + back_buffer_offset) = pixel_value;
497 					pixel++;
498 				} while ((pixel < cmd_pixel_end) &&
499 					 (*pixel == pixel_value));
500 
501 				/* immediately after raw data is repeat byte */
502 				*cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
503 
504 				/* Then start another raw pixel span */
505 				raw_pixel_start = pixel;
506 				raw_pixels_count_byte = cmd++;
507 			}
508 		}
509 
510 		if (pixel > raw_pixel_start) {
511 			/* finalize last RAW span */
512 			*raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
513 		} else {
514 			/* undo unused byte */
515 			cmd--;
516 		}
517 
518 		*cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
519 		dev_addr += (u8 *)pixel - (u8 *)cmd_pixel_start;
520 	}
521 
522 	if (cmd_buffer_end - MIN_RLX_CMD_BYTES <= cmd) {
523 		/* Fill leftover bytes with no-ops */
524 		if (cmd_buffer_end > cmd)
525 			memset(cmd, 0xAF, cmd_buffer_end - cmd);
526 		cmd = (uint8_t *) cmd_buffer_end;
527 	}
528 
529 	*command_buffer_ptr = cmd;
530 	*pixel_start_ptr = pixel;
531 	*device_address_ptr = dev_addr;
532 }
533 
534 /*
535  * There are 3 copies of every pixel: The front buffer that the fbdev
536  * client renders to, the actual framebuffer across the USB bus in hardware
537  * (that we can only write to, slowly, and can never read), and (optionally)
538  * our shadow copy that tracks what's been sent to that hardware buffer.
539  */
540 static int dlfb_render_hline(struct dlfb_data *dlfb, struct urb **urb_ptr,
541 			      const char *front, char **urb_buf_ptr,
542 			      u32 byte_offset, u32 byte_width,
543 			      int *ident_ptr, int *sent_ptr)
544 {
545 	const u8 *line_start, *line_end, *next_pixel;
546 	u32 dev_addr = dlfb->base16 + byte_offset;
547 	struct urb *urb = *urb_ptr;
548 	u8 *cmd = *urb_buf_ptr;
549 	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
550 	unsigned long back_buffer_offset = 0;
551 
552 	line_start = (u8 *) (front + byte_offset);
553 	next_pixel = line_start;
554 	line_end = next_pixel + byte_width;
555 
556 	if (dlfb->backing_buffer) {
557 		int offset;
558 		const u8 *back_start = (u8 *) (dlfb->backing_buffer
559 						+ byte_offset);
560 
561 		back_buffer_offset = (unsigned long)back_start - (unsigned long)line_start;
562 
563 		*ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
564 			&byte_width);
565 
566 		offset = next_pixel - line_start;
567 		line_end = next_pixel + byte_width;
568 		dev_addr += offset;
569 		back_start += offset;
570 		line_start += offset;
571 	}
572 
573 	while (next_pixel < line_end) {
574 
575 		dlfb_compress_hline((const uint16_t **) &next_pixel,
576 			     (const uint16_t *) line_end, &dev_addr,
577 			(u8 **) &cmd, (u8 *) cmd_end, back_buffer_offset,
578 			ident_ptr);
579 
580 		if (cmd >= cmd_end) {
581 			int len = cmd - (u8 *) urb->transfer_buffer;
582 			if (dlfb_submit_urb(dlfb, urb, len))
583 				return 1; /* lost pixels is set */
584 			*sent_ptr += len;
585 			urb = dlfb_get_urb(dlfb);
586 			if (!urb)
587 				return 1; /* lost_pixels is set */
588 			*urb_ptr = urb;
589 			cmd = urb->transfer_buffer;
590 			cmd_end = &cmd[urb->transfer_buffer_length];
591 		}
592 	}
593 
594 	*urb_buf_ptr = cmd;
595 
596 	return 0;
597 }
598 
599 static int dlfb_handle_damage(struct dlfb_data *dlfb, int x, int y, int width, int height)
600 {
601 	int i, ret;
602 	char *cmd;
603 	cycles_t start_cycles, end_cycles;
604 	int bytes_sent = 0;
605 	int bytes_identical = 0;
606 	struct urb *urb;
607 	int aligned_x;
608 
609 	start_cycles = get_cycles();
610 
611 	mutex_lock(&dlfb->render_mutex);
612 
613 	aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
614 	width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
615 	x = aligned_x;
616 
617 	if ((width <= 0) ||
618 	    (x + width > dlfb->info->var.xres) ||
619 	    (y + height > dlfb->info->var.yres)) {
620 		ret = -EINVAL;
621 		goto unlock_ret;
622 	}
623 
624 	if (!atomic_read(&dlfb->usb_active)) {
625 		ret = 0;
626 		goto unlock_ret;
627 	}
628 
629 	urb = dlfb_get_urb(dlfb);
630 	if (!urb) {
631 		ret = 0;
632 		goto unlock_ret;
633 	}
634 	cmd = urb->transfer_buffer;
635 
636 	for (i = y; i < y + height ; i++) {
637 		const int line_offset = dlfb->info->fix.line_length * i;
638 		const int byte_offset = line_offset + (x * BPP);
639 
640 		if (dlfb_render_hline(dlfb, &urb,
641 				      (char *) dlfb->info->fix.smem_start,
642 				      &cmd, byte_offset, width * BPP,
643 				      &bytes_identical, &bytes_sent))
644 			goto error;
645 	}
646 
647 	if (cmd > (char *) urb->transfer_buffer) {
648 		int len;
649 		if (cmd < (char *) urb->transfer_buffer + urb->transfer_buffer_length)
650 			*cmd++ = 0xAF;
651 		/* Send partial buffer remaining before exiting */
652 		len = cmd - (char *) urb->transfer_buffer;
653 		dlfb_submit_urb(dlfb, urb, len);
654 		bytes_sent += len;
655 	} else
656 		dlfb_urb_completion(urb);
657 
658 error:
659 	atomic_add(bytes_sent, &dlfb->bytes_sent);
660 	atomic_add(bytes_identical, &dlfb->bytes_identical);
661 	atomic_add(width*height*2, &dlfb->bytes_rendered);
662 	end_cycles = get_cycles();
663 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
664 		    >> 10)), /* Kcycles */
665 		   &dlfb->cpu_kcycles_used);
666 
667 	ret = 0;
668 
669 unlock_ret:
670 	mutex_unlock(&dlfb->render_mutex);
671 	return ret;
672 }
673 
674 static void dlfb_init_damage(struct dlfb_data *dlfb)
675 {
676 	dlfb->damage_x = INT_MAX;
677 	dlfb->damage_x2 = 0;
678 	dlfb->damage_y = INT_MAX;
679 	dlfb->damage_y2 = 0;
680 }
681 
682 static void dlfb_damage_work(struct work_struct *w)
683 {
684 	struct dlfb_data *dlfb = container_of(w, struct dlfb_data, damage_work);
685 	int x, x2, y, y2;
686 
687 	spin_lock_irq(&dlfb->damage_lock);
688 	x = dlfb->damage_x;
689 	x2 = dlfb->damage_x2;
690 	y = dlfb->damage_y;
691 	y2 = dlfb->damage_y2;
692 	dlfb_init_damage(dlfb);
693 	spin_unlock_irq(&dlfb->damage_lock);
694 
695 	if (x < x2 && y < y2)
696 		dlfb_handle_damage(dlfb, x, y, x2 - x, y2 - y);
697 }
698 
699 static void dlfb_offload_damage(struct dlfb_data *dlfb, int x, int y, int width, int height)
700 {
701 	unsigned long flags;
702 	int x2 = x + width;
703 	int y2 = y + height;
704 
705 	if (x >= x2 || y >= y2)
706 		return;
707 
708 	spin_lock_irqsave(&dlfb->damage_lock, flags);
709 	dlfb->damage_x = min(x, dlfb->damage_x);
710 	dlfb->damage_x2 = max(x2, dlfb->damage_x2);
711 	dlfb->damage_y = min(y, dlfb->damage_y);
712 	dlfb->damage_y2 = max(y2, dlfb->damage_y2);
713 	spin_unlock_irqrestore(&dlfb->damage_lock, flags);
714 
715 	schedule_work(&dlfb->damage_work);
716 }
717 
718 /*
719  * Path triggered by usermode clients who write to filesystem
720  * e.g. cat filename > /dev/fb1
721  * Not used by X Windows or text-mode console. But useful for testing.
722  * Slow because of extra copy and we must assume all pixels dirty.
723  */
724 static ssize_t dlfb_ops_write(struct fb_info *info, const char __user *buf,
725 			  size_t count, loff_t *ppos)
726 {
727 	ssize_t result;
728 	struct dlfb_data *dlfb = info->par;
729 	u32 offset = (u32) *ppos;
730 
731 	result = fb_sys_write(info, buf, count, ppos);
732 
733 	if (result > 0) {
734 		int start = max((int)(offset / info->fix.line_length), 0);
735 		int lines = min((u32)((result / info->fix.line_length) + 1),
736 				(u32)info->var.yres);
737 
738 		dlfb_handle_damage(dlfb, 0, start, info->var.xres,
739 			lines);
740 	}
741 
742 	return result;
743 }
744 
745 /* hardware has native COPY command (see libdlo), but not worth it for fbcon */
746 static void dlfb_ops_copyarea(struct fb_info *info,
747 				const struct fb_copyarea *area)
748 {
749 
750 	struct dlfb_data *dlfb = info->par;
751 
752 	sys_copyarea(info, area);
753 
754 	dlfb_offload_damage(dlfb, area->dx, area->dy,
755 			area->width, area->height);
756 }
757 
758 static void dlfb_ops_imageblit(struct fb_info *info,
759 				const struct fb_image *image)
760 {
761 	struct dlfb_data *dlfb = info->par;
762 
763 	sys_imageblit(info, image);
764 
765 	dlfb_offload_damage(dlfb, image->dx, image->dy,
766 			image->width, image->height);
767 }
768 
769 static void dlfb_ops_fillrect(struct fb_info *info,
770 			  const struct fb_fillrect *rect)
771 {
772 	struct dlfb_data *dlfb = info->par;
773 
774 	sys_fillrect(info, rect);
775 
776 	dlfb_offload_damage(dlfb, rect->dx, rect->dy, rect->width,
777 			      rect->height);
778 }
779 
780 /*
781  * NOTE: fb_defio.c is holding info->fbdefio.mutex
782  *   Touching ANY framebuffer memory that triggers a page fault
783  *   in fb_defio will cause a deadlock, when it also tries to
784  *   grab the same mutex.
785  */
786 static void dlfb_dpy_deferred_io(struct fb_info *info, struct list_head *pagereflist)
787 {
788 	struct fb_deferred_io_pageref *pageref;
789 	struct dlfb_data *dlfb = info->par;
790 	struct urb *urb;
791 	char *cmd;
792 	cycles_t start_cycles, end_cycles;
793 	int bytes_sent = 0;
794 	int bytes_identical = 0;
795 	int bytes_rendered = 0;
796 
797 	mutex_lock(&dlfb->render_mutex);
798 
799 	if (!fb_defio)
800 		goto unlock_ret;
801 
802 	if (!atomic_read(&dlfb->usb_active))
803 		goto unlock_ret;
804 
805 	start_cycles = get_cycles();
806 
807 	urb = dlfb_get_urb(dlfb);
808 	if (!urb)
809 		goto unlock_ret;
810 
811 	cmd = urb->transfer_buffer;
812 
813 	/* walk the written page list and render each to device */
814 	list_for_each_entry(pageref, pagereflist, list) {
815 		if (dlfb_render_hline(dlfb, &urb, (char *) info->fix.smem_start,
816 				      &cmd, pageref->offset, PAGE_SIZE,
817 				      &bytes_identical, &bytes_sent))
818 			goto error;
819 		bytes_rendered += PAGE_SIZE;
820 	}
821 
822 	if (cmd > (char *) urb->transfer_buffer) {
823 		int len;
824 		if (cmd < (char *) urb->transfer_buffer + urb->transfer_buffer_length)
825 			*cmd++ = 0xAF;
826 		/* Send partial buffer remaining before exiting */
827 		len = cmd - (char *) urb->transfer_buffer;
828 		dlfb_submit_urb(dlfb, urb, len);
829 		bytes_sent += len;
830 	} else
831 		dlfb_urb_completion(urb);
832 
833 error:
834 	atomic_add(bytes_sent, &dlfb->bytes_sent);
835 	atomic_add(bytes_identical, &dlfb->bytes_identical);
836 	atomic_add(bytes_rendered, &dlfb->bytes_rendered);
837 	end_cycles = get_cycles();
838 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
839 		    >> 10)), /* Kcycles */
840 		   &dlfb->cpu_kcycles_used);
841 unlock_ret:
842 	mutex_unlock(&dlfb->render_mutex);
843 }
844 
845 static int dlfb_get_edid(struct dlfb_data *dlfb, char *edid, int len)
846 {
847 	int i, ret;
848 	char *rbuf;
849 
850 	rbuf = kmalloc(2, GFP_KERNEL);
851 	if (!rbuf)
852 		return 0;
853 
854 	for (i = 0; i < len; i++) {
855 		ret = usb_control_msg(dlfb->udev,
856 				      usb_rcvctrlpipe(dlfb->udev, 0), 0x02,
857 				      (0x80 | (0x02 << 5)), i << 8, 0xA1,
858 				      rbuf, 2, USB_CTRL_GET_TIMEOUT);
859 		if (ret < 2) {
860 			dev_err(&dlfb->udev->dev,
861 				"Read EDID byte %d failed: %d\n", i, ret);
862 			i--;
863 			break;
864 		}
865 		edid[i] = rbuf[1];
866 	}
867 
868 	kfree(rbuf);
869 
870 	return i;
871 }
872 
873 static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
874 				unsigned long arg)
875 {
876 
877 	struct dlfb_data *dlfb = info->par;
878 
879 	if (!atomic_read(&dlfb->usb_active))
880 		return 0;
881 
882 	/* TODO: Update X server to get this from sysfs instead */
883 	if (cmd == DLFB_IOCTL_RETURN_EDID) {
884 		void __user *edid = (void __user *)arg;
885 		if (copy_to_user(edid, dlfb->edid, dlfb->edid_size))
886 			return -EFAULT;
887 		return 0;
888 	}
889 
890 	/* TODO: Help propose a standard fb.h ioctl to report mmap damage */
891 	if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
892 		struct dloarea area;
893 
894 		if (copy_from_user(&area, (void __user *)arg,
895 				  sizeof(struct dloarea)))
896 			return -EFAULT;
897 
898 		/*
899 		 * If we have a damage-aware client, turn fb_defio "off"
900 		 * To avoid perf imact of unnecessary page fault handling.
901 		 * Done by resetting the delay for this fb_info to a very
902 		 * long period. Pages will become writable and stay that way.
903 		 * Reset to normal value when all clients have closed this fb.
904 		 */
905 		if (info->fbdefio)
906 			info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
907 
908 		if (area.x < 0)
909 			area.x = 0;
910 
911 		if (area.x > info->var.xres)
912 			area.x = info->var.xres;
913 
914 		if (area.y < 0)
915 			area.y = 0;
916 
917 		if (area.y > info->var.yres)
918 			area.y = info->var.yres;
919 
920 		dlfb_handle_damage(dlfb, area.x, area.y, area.w, area.h);
921 	}
922 
923 	return 0;
924 }
925 
926 /* taken from vesafb */
927 static int
928 dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
929 	       unsigned blue, unsigned transp, struct fb_info *info)
930 {
931 	int err = 0;
932 
933 	if (regno >= info->cmap.len)
934 		return 1;
935 
936 	if (regno < 16) {
937 		if (info->var.red.offset == 10) {
938 			/* 1:5:5:5 */
939 			((u32 *) (info->pseudo_palette))[regno] =
940 			    ((red & 0xf800) >> 1) |
941 			    ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
942 		} else {
943 			/* 0:5:6:5 */
944 			((u32 *) (info->pseudo_palette))[regno] =
945 			    ((red & 0xf800)) |
946 			    ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
947 		}
948 	}
949 
950 	return err;
951 }
952 
953 /*
954  * It's common for several clients to have framebuffer open simultaneously.
955  * e.g. both fbcon and X. Makes things interesting.
956  * Assumes caller is holding info->lock (for open and release at least)
957  */
958 static int dlfb_ops_open(struct fb_info *info, int user)
959 {
960 	struct dlfb_data *dlfb = info->par;
961 
962 	/*
963 	 * fbcon aggressively connects to first framebuffer it finds,
964 	 * preventing other clients (X) from working properly. Usually
965 	 * not what the user wants. Fail by default with option to enable.
966 	 */
967 	if ((user == 0) && (!console))
968 		return -EBUSY;
969 
970 	/* If the USB device is gone, we don't accept new opens */
971 	if (dlfb->virtualized)
972 		return -ENODEV;
973 
974 	dlfb->fb_count++;
975 
976 	if (fb_defio && (info->fbdefio == NULL)) {
977 		/* enable defio at last moment if not disabled by client */
978 
979 		struct fb_deferred_io *fbdefio;
980 
981 		fbdefio = kzalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
982 
983 		if (fbdefio) {
984 			fbdefio->delay = DL_DEFIO_WRITE_DELAY;
985 			fbdefio->sort_pagereflist = true;
986 			fbdefio->deferred_io = dlfb_dpy_deferred_io;
987 		}
988 
989 		info->fbdefio = fbdefio;
990 		fb_deferred_io_init(info);
991 	}
992 
993 	dev_dbg(info->dev, "open, user=%d fb_info=%p count=%d\n",
994 		user, info, dlfb->fb_count);
995 
996 	return 0;
997 }
998 
999 static void dlfb_ops_destroy(struct fb_info *info)
1000 {
1001 	struct dlfb_data *dlfb = info->par;
1002 
1003 	cancel_work_sync(&dlfb->damage_work);
1004 
1005 	mutex_destroy(&dlfb->render_mutex);
1006 
1007 	if (info->cmap.len != 0)
1008 		fb_dealloc_cmap(&info->cmap);
1009 	if (info->monspecs.modedb)
1010 		fb_destroy_modedb(info->monspecs.modedb);
1011 	vfree(info->screen_buffer);
1012 
1013 	fb_destroy_modelist(&info->modelist);
1014 
1015 	while (!list_empty(&dlfb->deferred_free)) {
1016 		struct dlfb_deferred_free *d = list_entry(dlfb->deferred_free.next, struct dlfb_deferred_free, list);
1017 		list_del(&d->list);
1018 		vfree(d->mem);
1019 		kfree(d);
1020 	}
1021 	vfree(dlfb->backing_buffer);
1022 	kfree(dlfb->edid);
1023 	dlfb_free_urb_list(dlfb);
1024 	usb_put_dev(dlfb->udev);
1025 	kfree(dlfb);
1026 
1027 	/* Assume info structure is freed after this point */
1028 	framebuffer_release(info);
1029 }
1030 
1031 /*
1032  * Assumes caller is holding info->lock mutex (for open and release at least)
1033  */
1034 static int dlfb_ops_release(struct fb_info *info, int user)
1035 {
1036 	struct dlfb_data *dlfb = info->par;
1037 
1038 	dlfb->fb_count--;
1039 
1040 	if ((dlfb->fb_count == 0) && (info->fbdefio)) {
1041 		fb_deferred_io_cleanup(info);
1042 		kfree(info->fbdefio);
1043 		info->fbdefio = NULL;
1044 	}
1045 
1046 	dev_dbg(info->dev, "release, user=%d count=%d\n", user, dlfb->fb_count);
1047 
1048 	return 0;
1049 }
1050 
1051 /*
1052  * Check whether a video mode is supported by the DisplayLink chip
1053  * We start from monitor's modes, so don't need to filter that here
1054  */
1055 static int dlfb_is_valid_mode(struct fb_videomode *mode, struct dlfb_data *dlfb)
1056 {
1057 	if (mode->xres * mode->yres > dlfb->sku_pixel_limit)
1058 		return 0;
1059 
1060 	return 1;
1061 }
1062 
1063 static void dlfb_var_color_format(struct fb_var_screeninfo *var)
1064 {
1065 	const struct fb_bitfield red = { 11, 5, 0 };
1066 	const struct fb_bitfield green = { 5, 6, 0 };
1067 	const struct fb_bitfield blue = { 0, 5, 0 };
1068 
1069 	var->bits_per_pixel = 16;
1070 	var->red = red;
1071 	var->green = green;
1072 	var->blue = blue;
1073 }
1074 
1075 static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
1076 				struct fb_info *info)
1077 {
1078 	struct fb_videomode mode;
1079 	struct dlfb_data *dlfb = info->par;
1080 
1081 	/* set device-specific elements of var unrelated to mode */
1082 	dlfb_var_color_format(var);
1083 
1084 	fb_var_to_videomode(&mode, var);
1085 
1086 	if (!dlfb_is_valid_mode(&mode, dlfb))
1087 		return -EINVAL;
1088 
1089 	return 0;
1090 }
1091 
1092 static int dlfb_ops_set_par(struct fb_info *info)
1093 {
1094 	struct dlfb_data *dlfb = info->par;
1095 	int result;
1096 	u16 *pix_framebuffer;
1097 	int i;
1098 	struct fb_var_screeninfo fvs;
1099 	u32 line_length = info->var.xres * (info->var.bits_per_pixel / 8);
1100 
1101 	/* clear the activate field because it causes spurious miscompares */
1102 	fvs = info->var;
1103 	fvs.activate = 0;
1104 	fvs.vmode &= ~FB_VMODE_SMOOTH_XPAN;
1105 
1106 	if (!memcmp(&dlfb->current_mode, &fvs, sizeof(struct fb_var_screeninfo)))
1107 		return 0;
1108 
1109 	result = dlfb_realloc_framebuffer(dlfb, info, info->var.yres * line_length);
1110 	if (result)
1111 		return result;
1112 
1113 	result = dlfb_set_video_mode(dlfb, &info->var);
1114 
1115 	if (result)
1116 		return result;
1117 
1118 	dlfb->current_mode = fvs;
1119 	info->fix.line_length = line_length;
1120 
1121 	if (dlfb->fb_count == 0) {
1122 
1123 		/* paint greenscreen */
1124 
1125 		pix_framebuffer = (u16 *)info->screen_buffer;
1126 		for (i = 0; i < info->fix.smem_len / 2; i++)
1127 			pix_framebuffer[i] = 0x37e6;
1128 	}
1129 
1130 	dlfb_handle_damage(dlfb, 0, 0, info->var.xres, info->var.yres);
1131 
1132 	return 0;
1133 }
1134 
1135 /* To fonzi the jukebox (e.g. make blanking changes take effect) */
1136 static char *dlfb_dummy_render(char *buf)
1137 {
1138 	*buf++ = 0xAF;
1139 	*buf++ = 0x6A; /* copy */
1140 	*buf++ = 0x00; /* from address*/
1141 	*buf++ = 0x00;
1142 	*buf++ = 0x00;
1143 	*buf++ = 0x01; /* one pixel */
1144 	*buf++ = 0x00; /* to address */
1145 	*buf++ = 0x00;
1146 	*buf++ = 0x00;
1147 	return buf;
1148 }
1149 
1150 /*
1151  * In order to come back from full DPMS off, we need to set the mode again
1152  */
1153 static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
1154 {
1155 	struct dlfb_data *dlfb = info->par;
1156 	char *bufptr;
1157 	struct urb *urb;
1158 
1159 	dev_dbg(info->dev, "blank, mode %d --> %d\n",
1160 		dlfb->blank_mode, blank_mode);
1161 
1162 	if ((dlfb->blank_mode == FB_BLANK_POWERDOWN) &&
1163 	    (blank_mode != FB_BLANK_POWERDOWN)) {
1164 
1165 		/* returning from powerdown requires a fresh modeset */
1166 		dlfb_set_video_mode(dlfb, &info->var);
1167 	}
1168 
1169 	urb = dlfb_get_urb(dlfb);
1170 	if (!urb)
1171 		return 0;
1172 
1173 	bufptr = (char *) urb->transfer_buffer;
1174 	bufptr = dlfb_vidreg_lock(bufptr);
1175 	bufptr = dlfb_blanking(bufptr, blank_mode);
1176 	bufptr = dlfb_vidreg_unlock(bufptr);
1177 
1178 	/* seems like a render op is needed to have blank change take effect */
1179 	bufptr = dlfb_dummy_render(bufptr);
1180 
1181 	dlfb_submit_urb(dlfb, urb, bufptr -
1182 			(char *) urb->transfer_buffer);
1183 
1184 	dlfb->blank_mode = blank_mode;
1185 
1186 	return 0;
1187 }
1188 
1189 static const struct fb_ops dlfb_ops = {
1190 	.owner = THIS_MODULE,
1191 	.fb_read = fb_sys_read,
1192 	.fb_write = dlfb_ops_write,
1193 	.fb_setcolreg = dlfb_ops_setcolreg,
1194 	.fb_fillrect = dlfb_ops_fillrect,
1195 	.fb_copyarea = dlfb_ops_copyarea,
1196 	.fb_imageblit = dlfb_ops_imageblit,
1197 	.fb_mmap = dlfb_ops_mmap,
1198 	.fb_ioctl = dlfb_ops_ioctl,
1199 	.fb_open = dlfb_ops_open,
1200 	.fb_release = dlfb_ops_release,
1201 	.fb_blank = dlfb_ops_blank,
1202 	.fb_check_var = dlfb_ops_check_var,
1203 	.fb_set_par = dlfb_ops_set_par,
1204 	.fb_destroy = dlfb_ops_destroy,
1205 };
1206 
1207 
1208 static void dlfb_deferred_vfree(struct dlfb_data *dlfb, void *mem)
1209 {
1210 	struct dlfb_deferred_free *d = kmalloc(sizeof(struct dlfb_deferred_free), GFP_KERNEL);
1211 	if (!d)
1212 		return;
1213 	d->mem = mem;
1214 	list_add(&d->list, &dlfb->deferred_free);
1215 }
1216 
1217 /*
1218  * Assumes &info->lock held by caller
1219  * Assumes no active clients have framebuffer open
1220  */
1221 static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len)
1222 {
1223 	u32 old_len = info->fix.smem_len;
1224 	const void *old_fb = info->screen_buffer;
1225 	unsigned char *new_fb;
1226 	unsigned char *new_back = NULL;
1227 
1228 	new_len = PAGE_ALIGN(new_len);
1229 
1230 	if (new_len > old_len) {
1231 		/*
1232 		 * Alloc system memory for virtual framebuffer
1233 		 */
1234 		new_fb = vmalloc(new_len);
1235 		if (!new_fb) {
1236 			dev_err(info->dev, "Virtual framebuffer alloc failed\n");
1237 			return -ENOMEM;
1238 		}
1239 		memset(new_fb, 0xff, new_len);
1240 
1241 		if (info->screen_buffer) {
1242 			memcpy(new_fb, old_fb, old_len);
1243 			dlfb_deferred_vfree(dlfb, info->screen_buffer);
1244 		}
1245 
1246 		info->screen_buffer = new_fb;
1247 		info->fix.smem_len = new_len;
1248 		info->fix.smem_start = (unsigned long) new_fb;
1249 		info->flags = udlfb_info_flags;
1250 
1251 		/*
1252 		 * Second framebuffer copy to mirror the framebuffer state
1253 		 * on the physical USB device. We can function without this.
1254 		 * But with imperfect damage info we may send pixels over USB
1255 		 * that were, in fact, unchanged - wasting limited USB bandwidth
1256 		 */
1257 		if (shadow)
1258 			new_back = vzalloc(new_len);
1259 		if (!new_back)
1260 			dev_info(info->dev,
1261 				 "No shadow/backing buffer allocated\n");
1262 		else {
1263 			dlfb_deferred_vfree(dlfb, dlfb->backing_buffer);
1264 			dlfb->backing_buffer = new_back;
1265 		}
1266 	}
1267 	return 0;
1268 }
1269 
1270 /*
1271  * 1) Get EDID from hw, or use sw default
1272  * 2) Parse into various fb_info structs
1273  * 3) Allocate virtual framebuffer memory to back highest res mode
1274  *
1275  * Parses EDID into three places used by various parts of fbdev:
1276  * fb_var_screeninfo contains the timing of the monitor's preferred mode
1277  * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
1278  * fb_info.modelist is a linked list of all monitor & VESA modes which work
1279  *
1280  * If EDID is not readable/valid, then modelist is all VESA modes,
1281  * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
1282  * Returns 0 if successful
1283  */
1284 static int dlfb_setup_modes(struct dlfb_data *dlfb,
1285 			   struct fb_info *info,
1286 			   char *default_edid, size_t default_edid_size)
1287 {
1288 	char *edid;
1289 	int i, result = 0, tries = 3;
1290 	struct device *dev = info->device;
1291 	struct fb_videomode *mode;
1292 	const struct fb_videomode *default_vmode = NULL;
1293 
1294 	if (info->dev) {
1295 		/* only use mutex if info has been registered */
1296 		mutex_lock(&info->lock);
1297 		/* parent device is used otherwise */
1298 		dev = info->dev;
1299 	}
1300 
1301 	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
1302 	if (!edid) {
1303 		result = -ENOMEM;
1304 		goto error;
1305 	}
1306 
1307 	fb_destroy_modelist(&info->modelist);
1308 	memset(&info->monspecs, 0, sizeof(info->monspecs));
1309 
1310 	/*
1311 	 * Try to (re)read EDID from hardware first
1312 	 * EDID data may return, but not parse as valid
1313 	 * Try again a few times, in case of e.g. analog cable noise
1314 	 */
1315 	while (tries--) {
1316 
1317 		i = dlfb_get_edid(dlfb, edid, EDID_LENGTH);
1318 
1319 		if (i >= EDID_LENGTH)
1320 			fb_edid_to_monspecs(edid, &info->monspecs);
1321 
1322 		if (info->monspecs.modedb_len > 0) {
1323 			dlfb->edid = edid;
1324 			dlfb->edid_size = i;
1325 			break;
1326 		}
1327 	}
1328 
1329 	/* If that fails, use a previously returned EDID if available */
1330 	if (info->monspecs.modedb_len == 0) {
1331 		dev_err(dev, "Unable to get valid EDID from device/display\n");
1332 
1333 		if (dlfb->edid) {
1334 			fb_edid_to_monspecs(dlfb->edid, &info->monspecs);
1335 			if (info->monspecs.modedb_len > 0)
1336 				dev_err(dev, "Using previously queried EDID\n");
1337 		}
1338 	}
1339 
1340 	/* If that fails, use the default EDID we were handed */
1341 	if (info->monspecs.modedb_len == 0) {
1342 		if (default_edid_size >= EDID_LENGTH) {
1343 			fb_edid_to_monspecs(default_edid, &info->monspecs);
1344 			if (info->monspecs.modedb_len > 0) {
1345 				memcpy(edid, default_edid, default_edid_size);
1346 				dlfb->edid = edid;
1347 				dlfb->edid_size = default_edid_size;
1348 				dev_err(dev, "Using default/backup EDID\n");
1349 			}
1350 		}
1351 	}
1352 
1353 	/* If we've got modes, let's pick a best default mode */
1354 	if (info->monspecs.modedb_len > 0) {
1355 
1356 		for (i = 0; i < info->monspecs.modedb_len; i++) {
1357 			mode = &info->monspecs.modedb[i];
1358 			if (dlfb_is_valid_mode(mode, dlfb)) {
1359 				fb_add_videomode(mode, &info->modelist);
1360 			} else {
1361 				dev_dbg(dev, "Specified mode %dx%d too big\n",
1362 					mode->xres, mode->yres);
1363 				if (i == 0)
1364 					/* if we've removed top/best mode */
1365 					info->monspecs.misc
1366 						&= ~FB_MISC_1ST_DETAIL;
1367 			}
1368 		}
1369 
1370 		default_vmode = fb_find_best_display(&info->monspecs,
1371 						     &info->modelist);
1372 	}
1373 
1374 	/* If everything else has failed, fall back to safe default mode */
1375 	if (default_vmode == NULL) {
1376 
1377 		struct fb_videomode fb_vmode = {0};
1378 
1379 		/*
1380 		 * Add the standard VESA modes to our modelist
1381 		 * Since we don't have EDID, there may be modes that
1382 		 * overspec monitor and/or are incorrect aspect ratio, etc.
1383 		 * But at least the user has a chance to choose
1384 		 */
1385 		for (i = 0; i < VESA_MODEDB_SIZE; i++) {
1386 			mode = (struct fb_videomode *)&vesa_modes[i];
1387 			if (dlfb_is_valid_mode(mode, dlfb))
1388 				fb_add_videomode(mode, &info->modelist);
1389 			else
1390 				dev_dbg(dev, "VESA mode %dx%d too big\n",
1391 					mode->xres, mode->yres);
1392 		}
1393 
1394 		/*
1395 		 * default to resolution safe for projectors
1396 		 * (since they are most common case without EDID)
1397 		 */
1398 		fb_vmode.xres = 800;
1399 		fb_vmode.yres = 600;
1400 		fb_vmode.refresh = 60;
1401 		default_vmode = fb_find_nearest_mode(&fb_vmode,
1402 						     &info->modelist);
1403 	}
1404 
1405 	/* If we have good mode and no active clients*/
1406 	if ((default_vmode != NULL) && (dlfb->fb_count == 0)) {
1407 
1408 		fb_videomode_to_var(&info->var, default_vmode);
1409 		dlfb_var_color_format(&info->var);
1410 
1411 		/*
1412 		 * with mode size info, we can now alloc our framebuffer.
1413 		 */
1414 		memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
1415 	} else
1416 		result = -EINVAL;
1417 
1418 error:
1419 	if (edid && (dlfb->edid != edid))
1420 		kfree(edid);
1421 
1422 	if (info->dev)
1423 		mutex_unlock(&info->lock);
1424 
1425 	return result;
1426 }
1427 
1428 static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
1429 				   struct device_attribute *a, char *buf) {
1430 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1431 	struct dlfb_data *dlfb = fb_info->par;
1432 	return sysfs_emit(buf, "%u\n",
1433 			atomic_read(&dlfb->bytes_rendered));
1434 }
1435 
1436 static ssize_t metrics_bytes_identical_show(struct device *fbdev,
1437 				   struct device_attribute *a, char *buf) {
1438 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1439 	struct dlfb_data *dlfb = fb_info->par;
1440 	return sysfs_emit(buf, "%u\n",
1441 			atomic_read(&dlfb->bytes_identical));
1442 }
1443 
1444 static ssize_t metrics_bytes_sent_show(struct device *fbdev,
1445 				   struct device_attribute *a, char *buf) {
1446 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1447 	struct dlfb_data *dlfb = fb_info->par;
1448 	return sysfs_emit(buf, "%u\n",
1449 			atomic_read(&dlfb->bytes_sent));
1450 }
1451 
1452 static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
1453 				   struct device_attribute *a, char *buf) {
1454 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1455 	struct dlfb_data *dlfb = fb_info->par;
1456 	return sysfs_emit(buf, "%u\n",
1457 			atomic_read(&dlfb->cpu_kcycles_used));
1458 }
1459 
1460 static ssize_t edid_show(
1461 			struct file *filp,
1462 			struct kobject *kobj, struct bin_attribute *a,
1463 			 char *buf, loff_t off, size_t count) {
1464 	struct device *fbdev = kobj_to_dev(kobj);
1465 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1466 	struct dlfb_data *dlfb = fb_info->par;
1467 
1468 	if (dlfb->edid == NULL)
1469 		return 0;
1470 
1471 	if ((off >= dlfb->edid_size) || (count > dlfb->edid_size))
1472 		return 0;
1473 
1474 	if (off + count > dlfb->edid_size)
1475 		count = dlfb->edid_size - off;
1476 
1477 	memcpy(buf, dlfb->edid, count);
1478 
1479 	return count;
1480 }
1481 
1482 static ssize_t edid_store(
1483 			struct file *filp,
1484 			struct kobject *kobj, struct bin_attribute *a,
1485 			char *src, loff_t src_off, size_t src_size) {
1486 	struct device *fbdev = kobj_to_dev(kobj);
1487 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1488 	struct dlfb_data *dlfb = fb_info->par;
1489 	int ret;
1490 
1491 	/* We only support write of entire EDID at once, no offset*/
1492 	if ((src_size != EDID_LENGTH) || (src_off != 0))
1493 		return -EINVAL;
1494 
1495 	ret = dlfb_setup_modes(dlfb, fb_info, src, src_size);
1496 	if (ret)
1497 		return ret;
1498 
1499 	if (!dlfb->edid || memcmp(src, dlfb->edid, src_size))
1500 		return -EINVAL;
1501 
1502 	ret = dlfb_ops_set_par(fb_info);
1503 	if (ret)
1504 		return ret;
1505 
1506 	return src_size;
1507 }
1508 
1509 static ssize_t metrics_reset_store(struct device *fbdev,
1510 			   struct device_attribute *attr,
1511 			   const char *buf, size_t count)
1512 {
1513 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1514 	struct dlfb_data *dlfb = fb_info->par;
1515 
1516 	atomic_set(&dlfb->bytes_rendered, 0);
1517 	atomic_set(&dlfb->bytes_identical, 0);
1518 	atomic_set(&dlfb->bytes_sent, 0);
1519 	atomic_set(&dlfb->cpu_kcycles_used, 0);
1520 
1521 	return count;
1522 }
1523 
1524 static const struct bin_attribute edid_attr = {
1525 	.attr.name = "edid",
1526 	.attr.mode = 0666,
1527 	.size = EDID_LENGTH,
1528 	.read = edid_show,
1529 	.write = edid_store
1530 };
1531 
1532 static const struct device_attribute fb_device_attrs[] = {
1533 	__ATTR_RO(metrics_bytes_rendered),
1534 	__ATTR_RO(metrics_bytes_identical),
1535 	__ATTR_RO(metrics_bytes_sent),
1536 	__ATTR_RO(metrics_cpu_kcycles_used),
1537 	__ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
1538 };
1539 
1540 /*
1541  * This is necessary before we can communicate with the display controller.
1542  */
1543 static int dlfb_select_std_channel(struct dlfb_data *dlfb)
1544 {
1545 	int ret;
1546 	static const u8 set_def_chn[] = {
1547 				0x57, 0xCD, 0xDC, 0xA7,
1548 				0x1C, 0x88, 0x5E, 0x15,
1549 				0x60, 0xFE, 0xC6, 0x97,
1550 				0x16, 0x3D, 0x47, 0xF2  };
1551 
1552 	ret = usb_control_msg_send(dlfb->udev, 0, NR_USB_REQUEST_CHANNEL,
1553 			(USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
1554 			&set_def_chn, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT,
1555 			GFP_KERNEL);
1556 
1557 	return ret;
1558 }
1559 
1560 static int dlfb_parse_vendor_descriptor(struct dlfb_data *dlfb,
1561 					struct usb_interface *intf)
1562 {
1563 	char *desc;
1564 	char *buf;
1565 	char *desc_end;
1566 	int total_len;
1567 
1568 	buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
1569 	if (!buf)
1570 		return false;
1571 	desc = buf;
1572 
1573 	total_len = usb_get_descriptor(interface_to_usbdev(intf),
1574 					0x5f, /* vendor specific */
1575 					0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
1576 
1577 	/* if not found, look in configuration descriptor */
1578 	if (total_len < 0) {
1579 		if (0 == usb_get_extra_descriptor(intf->cur_altsetting,
1580 			0x5f, &desc))
1581 			total_len = (int) desc[0];
1582 	}
1583 
1584 	if (total_len > 5) {
1585 		dev_info(&intf->dev,
1586 			 "vendor descriptor length: %d data: %11ph\n",
1587 			 total_len, desc);
1588 
1589 		if ((desc[0] != total_len) || /* descriptor length */
1590 		    (desc[1] != 0x5f) ||   /* vendor descriptor type */
1591 		    (desc[2] != 0x01) ||   /* version (2 bytes) */
1592 		    (desc[3] != 0x00) ||
1593 		    (desc[4] != total_len - 2)) /* length after type */
1594 			goto unrecognized;
1595 
1596 		desc_end = desc + total_len;
1597 		desc += 5; /* the fixed header we've already parsed */
1598 
1599 		while (desc < desc_end) {
1600 			u8 length;
1601 			u16 key;
1602 
1603 			key = *desc++;
1604 			key |= (u16)*desc++ << 8;
1605 			length = *desc++;
1606 
1607 			switch (key) {
1608 			case 0x0200: { /* max_area */
1609 				u32 max_area = *desc++;
1610 				max_area |= (u32)*desc++ << 8;
1611 				max_area |= (u32)*desc++ << 16;
1612 				max_area |= (u32)*desc++ << 24;
1613 				dev_warn(&intf->dev,
1614 					 "DL chip limited to %d pixel modes\n",
1615 					 max_area);
1616 				dlfb->sku_pixel_limit = max_area;
1617 				break;
1618 			}
1619 			default:
1620 				break;
1621 			}
1622 			desc += length;
1623 		}
1624 	} else {
1625 		dev_info(&intf->dev, "vendor descriptor not available (%d)\n",
1626 			 total_len);
1627 	}
1628 
1629 	goto success;
1630 
1631 unrecognized:
1632 	/* allow udlfb to load for now even if firmware unrecognized */
1633 	dev_err(&intf->dev, "Unrecognized vendor firmware descriptor\n");
1634 
1635 success:
1636 	kfree(buf);
1637 	return true;
1638 }
1639 
1640 static int dlfb_usb_probe(struct usb_interface *intf,
1641 			  const struct usb_device_id *id)
1642 {
1643 	int i;
1644 	const struct device_attribute *attr;
1645 	struct dlfb_data *dlfb;
1646 	struct fb_info *info;
1647 	int retval;
1648 	struct usb_device *usbdev = interface_to_usbdev(intf);
1649 	static u8 out_ep[] = {OUT_EP_NUM + USB_DIR_OUT, 0};
1650 
1651 	/* usb initialization */
1652 	dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL);
1653 	if (!dlfb) {
1654 		dev_err(&intf->dev, "%s: failed to allocate dlfb\n", __func__);
1655 		return -ENOMEM;
1656 	}
1657 
1658 	INIT_LIST_HEAD(&dlfb->deferred_free);
1659 
1660 	dlfb->udev = usb_get_dev(usbdev);
1661 	usb_set_intfdata(intf, dlfb);
1662 
1663 	if (!usb_check_bulk_endpoints(intf, out_ep)) {
1664 		dev_err(&intf->dev, "Invalid DisplayLink device!\n");
1665 		retval = -EINVAL;
1666 		goto error;
1667 	}
1668 
1669 	dev_dbg(&intf->dev, "console enable=%d\n", console);
1670 	dev_dbg(&intf->dev, "fb_defio enable=%d\n", fb_defio);
1671 	dev_dbg(&intf->dev, "shadow enable=%d\n", shadow);
1672 
1673 	dlfb->sku_pixel_limit = 2048 * 1152; /* default to maximum */
1674 
1675 	if (!dlfb_parse_vendor_descriptor(dlfb, intf)) {
1676 		dev_err(&intf->dev,
1677 			"firmware not recognized, incompatible device?\n");
1678 		retval = -ENODEV;
1679 		goto error;
1680 	}
1681 
1682 	if (pixel_limit) {
1683 		dev_warn(&intf->dev,
1684 			 "DL chip limit of %d overridden to %d\n",
1685 			 dlfb->sku_pixel_limit, pixel_limit);
1686 		dlfb->sku_pixel_limit = pixel_limit;
1687 	}
1688 
1689 
1690 	/* allocates framebuffer driver structure, not framebuffer memory */
1691 	info = framebuffer_alloc(0, &dlfb->udev->dev);
1692 	if (!info) {
1693 		retval = -ENOMEM;
1694 		goto error;
1695 	}
1696 
1697 	dlfb->info = info;
1698 	info->par = dlfb;
1699 	info->pseudo_palette = dlfb->pseudo_palette;
1700 	dlfb->ops = dlfb_ops;
1701 	info->fbops = &dlfb->ops;
1702 
1703 	mutex_init(&dlfb->render_mutex);
1704 	dlfb_init_damage(dlfb);
1705 	spin_lock_init(&dlfb->damage_lock);
1706 	INIT_WORK(&dlfb->damage_work, dlfb_damage_work);
1707 
1708 	INIT_LIST_HEAD(&info->modelist);
1709 
1710 	if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
1711 		retval = -ENOMEM;
1712 		dev_err(&intf->dev, "unable to allocate urb list\n");
1713 		goto error;
1714 	}
1715 
1716 	/* We don't register a new USB class. Our client interface is dlfbev */
1717 
1718 	retval = fb_alloc_cmap(&info->cmap, 256, 0);
1719 	if (retval < 0) {
1720 		dev_err(info->device, "cmap allocation failed: %d\n", retval);
1721 		goto error;
1722 	}
1723 
1724 	retval = dlfb_setup_modes(dlfb, info, NULL, 0);
1725 	if (retval != 0) {
1726 		dev_err(info->device,
1727 			"unable to find common mode for display and adapter\n");
1728 		goto error;
1729 	}
1730 
1731 	/* ready to begin using device */
1732 
1733 	atomic_set(&dlfb->usb_active, 1);
1734 	dlfb_select_std_channel(dlfb);
1735 
1736 	dlfb_ops_check_var(&info->var, info);
1737 	retval = dlfb_ops_set_par(info);
1738 	if (retval)
1739 		goto error;
1740 
1741 	retval = register_framebuffer(info);
1742 	if (retval < 0) {
1743 		dev_err(info->device, "unable to register framebuffer: %d\n",
1744 			retval);
1745 		goto error;
1746 	}
1747 
1748 	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
1749 		attr = &fb_device_attrs[i];
1750 		retval = device_create_file(info->dev, attr);
1751 		if (retval)
1752 			dev_warn(info->device,
1753 				 "failed to create '%s' attribute: %d\n",
1754 				 attr->attr.name, retval);
1755 	}
1756 
1757 	retval = device_create_bin_file(info->dev, &edid_attr);
1758 	if (retval)
1759 		dev_warn(info->device, "failed to create '%s' attribute: %d\n",
1760 			 edid_attr.attr.name, retval);
1761 
1762 	dev_info(info->device,
1763 		 "%s is DisplayLink USB device (%dx%d, %dK framebuffer memory)\n",
1764 		 dev_name(info->dev), info->var.xres, info->var.yres,
1765 		 ((dlfb->backing_buffer) ?
1766 		 info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
1767 	return 0;
1768 
1769 error:
1770 	if (dlfb->info) {
1771 		dlfb_ops_destroy(dlfb->info);
1772 	} else {
1773 		usb_put_dev(dlfb->udev);
1774 		kfree(dlfb);
1775 	}
1776 	return retval;
1777 }
1778 
1779 static void dlfb_usb_disconnect(struct usb_interface *intf)
1780 {
1781 	struct dlfb_data *dlfb;
1782 	struct fb_info *info;
1783 	int i;
1784 
1785 	dlfb = usb_get_intfdata(intf);
1786 	info = dlfb->info;
1787 
1788 	dev_dbg(&intf->dev, "USB disconnect starting\n");
1789 
1790 	/* we virtualize until all fb clients release. Then we free */
1791 	dlfb->virtualized = true;
1792 
1793 	/* When non-active we'll update virtual framebuffer, but no new urbs */
1794 	atomic_set(&dlfb->usb_active, 0);
1795 
1796 	/* this function will wait for all in-flight urbs to complete */
1797 	dlfb_free_urb_list(dlfb);
1798 
1799 	/* remove udlfb's sysfs interfaces */
1800 	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
1801 		device_remove_file(info->dev, &fb_device_attrs[i]);
1802 	device_remove_bin_file(info->dev, &edid_attr);
1803 
1804 	unregister_framebuffer(info);
1805 }
1806 
1807 static struct usb_driver dlfb_driver = {
1808 	.name = "udlfb",
1809 	.probe = dlfb_usb_probe,
1810 	.disconnect = dlfb_usb_disconnect,
1811 	.id_table = id_table,
1812 };
1813 
1814 module_usb_driver(dlfb_driver);
1815 
1816 static void dlfb_urb_completion(struct urb *urb)
1817 {
1818 	struct urb_node *unode = urb->context;
1819 	struct dlfb_data *dlfb = unode->dlfb;
1820 	unsigned long flags;
1821 
1822 	switch (urb->status) {
1823 	case 0:
1824 		/* success */
1825 		break;
1826 	case -ECONNRESET:
1827 	case -ENOENT:
1828 	case -ESHUTDOWN:
1829 		/* sync/async unlink faults aren't errors */
1830 		break;
1831 	default:
1832 		dev_err(&dlfb->udev->dev,
1833 			"%s - nonzero write bulk status received: %d\n",
1834 			__func__, urb->status);
1835 		atomic_set(&dlfb->lost_pixels, 1);
1836 		break;
1837 	}
1838 
1839 	urb->transfer_buffer_length = dlfb->urbs.size; /* reset to actual */
1840 
1841 	spin_lock_irqsave(&dlfb->urbs.lock, flags);
1842 	list_add_tail(&unode->entry, &dlfb->urbs.list);
1843 	dlfb->urbs.available++;
1844 	spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1845 
1846 	up(&dlfb->urbs.limit_sem);
1847 }
1848 
1849 static void dlfb_free_urb_list(struct dlfb_data *dlfb)
1850 {
1851 	int count = dlfb->urbs.count;
1852 	struct list_head *node;
1853 	struct urb_node *unode;
1854 	struct urb *urb;
1855 
1856 	/* keep waiting and freeing, until we've got 'em all */
1857 	while (count--) {
1858 		down(&dlfb->urbs.limit_sem);
1859 
1860 		spin_lock_irq(&dlfb->urbs.lock);
1861 
1862 		node = dlfb->urbs.list.next; /* have reserved one with sem */
1863 		list_del_init(node);
1864 
1865 		spin_unlock_irq(&dlfb->urbs.lock);
1866 
1867 		unode = list_entry(node, struct urb_node, entry);
1868 		urb = unode->urb;
1869 
1870 		/* Free each separately allocated piece */
1871 		usb_free_coherent(urb->dev, dlfb->urbs.size,
1872 				  urb->transfer_buffer, urb->transfer_dma);
1873 		usb_free_urb(urb);
1874 		kfree(node);
1875 	}
1876 
1877 	dlfb->urbs.count = 0;
1878 }
1879 
1880 static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size)
1881 {
1882 	struct urb *urb;
1883 	struct urb_node *unode;
1884 	char *buf;
1885 	size_t wanted_size = count * size;
1886 
1887 	spin_lock_init(&dlfb->urbs.lock);
1888 
1889 retry:
1890 	dlfb->urbs.size = size;
1891 	INIT_LIST_HEAD(&dlfb->urbs.list);
1892 
1893 	sema_init(&dlfb->urbs.limit_sem, 0);
1894 	dlfb->urbs.count = 0;
1895 	dlfb->urbs.available = 0;
1896 
1897 	while (dlfb->urbs.count * size < wanted_size) {
1898 		unode = kzalloc(sizeof(*unode), GFP_KERNEL);
1899 		if (!unode)
1900 			break;
1901 		unode->dlfb = dlfb;
1902 
1903 		urb = usb_alloc_urb(0, GFP_KERNEL);
1904 		if (!urb) {
1905 			kfree(unode);
1906 			break;
1907 		}
1908 		unode->urb = urb;
1909 
1910 		buf = usb_alloc_coherent(dlfb->udev, size, GFP_KERNEL,
1911 					 &urb->transfer_dma);
1912 		if (!buf) {
1913 			kfree(unode);
1914 			usb_free_urb(urb);
1915 			if (size > PAGE_SIZE) {
1916 				size /= 2;
1917 				dlfb_free_urb_list(dlfb);
1918 				goto retry;
1919 			}
1920 			break;
1921 		}
1922 
1923 		/* urb->transfer_buffer_length set to actual before submit */
1924 		usb_fill_bulk_urb(urb, dlfb->udev,
1925 			usb_sndbulkpipe(dlfb->udev, OUT_EP_NUM),
1926 			buf, size, dlfb_urb_completion, unode);
1927 		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
1928 
1929 		list_add_tail(&unode->entry, &dlfb->urbs.list);
1930 
1931 		up(&dlfb->urbs.limit_sem);
1932 		dlfb->urbs.count++;
1933 		dlfb->urbs.available++;
1934 	}
1935 
1936 	return dlfb->urbs.count;
1937 }
1938 
1939 static struct urb *dlfb_get_urb(struct dlfb_data *dlfb)
1940 {
1941 	int ret;
1942 	struct list_head *entry;
1943 	struct urb_node *unode;
1944 
1945 	/* Wait for an in-flight buffer to complete and get re-queued */
1946 	ret = down_timeout(&dlfb->urbs.limit_sem, GET_URB_TIMEOUT);
1947 	if (ret) {
1948 		atomic_set(&dlfb->lost_pixels, 1);
1949 		dev_warn(&dlfb->udev->dev,
1950 			 "wait for urb interrupted: %d available: %d\n",
1951 			 ret, dlfb->urbs.available);
1952 		return NULL;
1953 	}
1954 
1955 	spin_lock_irq(&dlfb->urbs.lock);
1956 
1957 	BUG_ON(list_empty(&dlfb->urbs.list)); /* reserved one with limit_sem */
1958 	entry = dlfb->urbs.list.next;
1959 	list_del_init(entry);
1960 	dlfb->urbs.available--;
1961 
1962 	spin_unlock_irq(&dlfb->urbs.lock);
1963 
1964 	unode = list_entry(entry, struct urb_node, entry);
1965 	return unode->urb;
1966 }
1967 
1968 static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb *urb, size_t len)
1969 {
1970 	int ret;
1971 
1972 	BUG_ON(len > dlfb->urbs.size);
1973 
1974 	urb->transfer_buffer_length = len; /* set to actual payload len */
1975 	ret = usb_submit_urb(urb, GFP_KERNEL);
1976 	if (ret) {
1977 		dlfb_urb_completion(urb); /* because no one else will */
1978 		atomic_set(&dlfb->lost_pixels, 1);
1979 		dev_err(&dlfb->udev->dev, "submit urb error: %d\n", ret);
1980 	}
1981 	return ret;
1982 }
1983 
1984 module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1985 MODULE_PARM_DESC(console, "Allow fbcon to open framebuffer");
1986 
1987 module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1988 MODULE_PARM_DESC(fb_defio, "Page fault detection of mmap writes");
1989 
1990 module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1991 MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf");
1992 
1993 module_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1994 MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
1995 
1996 MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
1997 	      "Jaya Kumar <jayakumar.lkml@gmail.com>, "
1998 	      "Bernie Thompson <bernie@plugable.com>");
1999 MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
2000 MODULE_LICENSE("GPL");
2001 
2002