1 /*
2  * v4l2-dv-timings - dv-timings helper functions
3  *
4  * Copyright 2013 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
5  *
6  * This program is free software; you may redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; version 2 of the License.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
11  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
12  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
13  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
14  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
15  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
16  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
17  * SOFTWARE.
18  *
19  */
20 
21 #include <linux/module.h>
22 #include <linux/types.h>
23 #include <linux/kernel.h>
24 #include <linux/errno.h>
25 #include <linux/videodev2.h>
26 #include <linux/v4l2-dv-timings.h>
27 #include <media/v4l2-dv-timings.h>
28 #include <linux/math64.h>
29 
30 MODULE_AUTHOR("Hans Verkuil");
31 MODULE_DESCRIPTION("V4L2 DV Timings Helper Functions");
32 MODULE_LICENSE("GPL");
33 
34 const struct v4l2_dv_timings v4l2_dv_timings_presets[] = {
35 	V4L2_DV_BT_CEA_640X480P59_94,
36 	V4L2_DV_BT_CEA_720X480I59_94,
37 	V4L2_DV_BT_CEA_720X480P59_94,
38 	V4L2_DV_BT_CEA_720X576I50,
39 	V4L2_DV_BT_CEA_720X576P50,
40 	V4L2_DV_BT_CEA_1280X720P24,
41 	V4L2_DV_BT_CEA_1280X720P25,
42 	V4L2_DV_BT_CEA_1280X720P30,
43 	V4L2_DV_BT_CEA_1280X720P50,
44 	V4L2_DV_BT_CEA_1280X720P60,
45 	V4L2_DV_BT_CEA_1920X1080P24,
46 	V4L2_DV_BT_CEA_1920X1080P25,
47 	V4L2_DV_BT_CEA_1920X1080P30,
48 	V4L2_DV_BT_CEA_1920X1080I50,
49 	V4L2_DV_BT_CEA_1920X1080P50,
50 	V4L2_DV_BT_CEA_1920X1080I60,
51 	V4L2_DV_BT_CEA_1920X1080P60,
52 	V4L2_DV_BT_DMT_640X350P85,
53 	V4L2_DV_BT_DMT_640X400P85,
54 	V4L2_DV_BT_DMT_720X400P85,
55 	V4L2_DV_BT_DMT_640X480P72,
56 	V4L2_DV_BT_DMT_640X480P75,
57 	V4L2_DV_BT_DMT_640X480P85,
58 	V4L2_DV_BT_DMT_800X600P56,
59 	V4L2_DV_BT_DMT_800X600P60,
60 	V4L2_DV_BT_DMT_800X600P72,
61 	V4L2_DV_BT_DMT_800X600P75,
62 	V4L2_DV_BT_DMT_800X600P85,
63 	V4L2_DV_BT_DMT_800X600P120_RB,
64 	V4L2_DV_BT_DMT_848X480P60,
65 	V4L2_DV_BT_DMT_1024X768I43,
66 	V4L2_DV_BT_DMT_1024X768P60,
67 	V4L2_DV_BT_DMT_1024X768P70,
68 	V4L2_DV_BT_DMT_1024X768P75,
69 	V4L2_DV_BT_DMT_1024X768P85,
70 	V4L2_DV_BT_DMT_1024X768P120_RB,
71 	V4L2_DV_BT_DMT_1152X864P75,
72 	V4L2_DV_BT_DMT_1280X768P60_RB,
73 	V4L2_DV_BT_DMT_1280X768P60,
74 	V4L2_DV_BT_DMT_1280X768P75,
75 	V4L2_DV_BT_DMT_1280X768P85,
76 	V4L2_DV_BT_DMT_1280X768P120_RB,
77 	V4L2_DV_BT_DMT_1280X800P60_RB,
78 	V4L2_DV_BT_DMT_1280X800P60,
79 	V4L2_DV_BT_DMT_1280X800P75,
80 	V4L2_DV_BT_DMT_1280X800P85,
81 	V4L2_DV_BT_DMT_1280X800P120_RB,
82 	V4L2_DV_BT_DMT_1280X960P60,
83 	V4L2_DV_BT_DMT_1280X960P85,
84 	V4L2_DV_BT_DMT_1280X960P120_RB,
85 	V4L2_DV_BT_DMT_1280X1024P60,
86 	V4L2_DV_BT_DMT_1280X1024P75,
87 	V4L2_DV_BT_DMT_1280X1024P85,
88 	V4L2_DV_BT_DMT_1280X1024P120_RB,
89 	V4L2_DV_BT_DMT_1360X768P60,
90 	V4L2_DV_BT_DMT_1360X768P120_RB,
91 	V4L2_DV_BT_DMT_1366X768P60,
92 	V4L2_DV_BT_DMT_1366X768P60_RB,
93 	V4L2_DV_BT_DMT_1400X1050P60_RB,
94 	V4L2_DV_BT_DMT_1400X1050P60,
95 	V4L2_DV_BT_DMT_1400X1050P75,
96 	V4L2_DV_BT_DMT_1400X1050P85,
97 	V4L2_DV_BT_DMT_1400X1050P120_RB,
98 	V4L2_DV_BT_DMT_1440X900P60_RB,
99 	V4L2_DV_BT_DMT_1440X900P60,
100 	V4L2_DV_BT_DMT_1440X900P75,
101 	V4L2_DV_BT_DMT_1440X900P85,
102 	V4L2_DV_BT_DMT_1440X900P120_RB,
103 	V4L2_DV_BT_DMT_1600X900P60_RB,
104 	V4L2_DV_BT_DMT_1600X1200P60,
105 	V4L2_DV_BT_DMT_1600X1200P65,
106 	V4L2_DV_BT_DMT_1600X1200P70,
107 	V4L2_DV_BT_DMT_1600X1200P75,
108 	V4L2_DV_BT_DMT_1600X1200P85,
109 	V4L2_DV_BT_DMT_1600X1200P120_RB,
110 	V4L2_DV_BT_DMT_1680X1050P60_RB,
111 	V4L2_DV_BT_DMT_1680X1050P60,
112 	V4L2_DV_BT_DMT_1680X1050P75,
113 	V4L2_DV_BT_DMT_1680X1050P85,
114 	V4L2_DV_BT_DMT_1680X1050P120_RB,
115 	V4L2_DV_BT_DMT_1792X1344P60,
116 	V4L2_DV_BT_DMT_1792X1344P75,
117 	V4L2_DV_BT_DMT_1792X1344P120_RB,
118 	V4L2_DV_BT_DMT_1856X1392P60,
119 	V4L2_DV_BT_DMT_1856X1392P75,
120 	V4L2_DV_BT_DMT_1856X1392P120_RB,
121 	V4L2_DV_BT_DMT_1920X1200P60_RB,
122 	V4L2_DV_BT_DMT_1920X1200P60,
123 	V4L2_DV_BT_DMT_1920X1200P75,
124 	V4L2_DV_BT_DMT_1920X1200P85,
125 	V4L2_DV_BT_DMT_1920X1200P120_RB,
126 	V4L2_DV_BT_DMT_1920X1440P60,
127 	V4L2_DV_BT_DMT_1920X1440P75,
128 	V4L2_DV_BT_DMT_1920X1440P120_RB,
129 	V4L2_DV_BT_DMT_2048X1152P60_RB,
130 	V4L2_DV_BT_DMT_2560X1600P60_RB,
131 	V4L2_DV_BT_DMT_2560X1600P60,
132 	V4L2_DV_BT_DMT_2560X1600P75,
133 	V4L2_DV_BT_DMT_2560X1600P85,
134 	V4L2_DV_BT_DMT_2560X1600P120_RB,
135 	V4L2_DV_BT_CEA_3840X2160P24,
136 	V4L2_DV_BT_CEA_3840X2160P25,
137 	V4L2_DV_BT_CEA_3840X2160P30,
138 	V4L2_DV_BT_CEA_3840X2160P50,
139 	V4L2_DV_BT_CEA_3840X2160P60,
140 	V4L2_DV_BT_CEA_4096X2160P24,
141 	V4L2_DV_BT_CEA_4096X2160P25,
142 	V4L2_DV_BT_CEA_4096X2160P30,
143 	V4L2_DV_BT_CEA_4096X2160P50,
144 	V4L2_DV_BT_DMT_4096X2160P59_94_RB,
145 	V4L2_DV_BT_CEA_4096X2160P60,
146 	{ }
147 };
148 EXPORT_SYMBOL_GPL(v4l2_dv_timings_presets);
149 
150 bool v4l2_valid_dv_timings(const struct v4l2_dv_timings *t,
151 			   const struct v4l2_dv_timings_cap *dvcap,
152 			   v4l2_check_dv_timings_fnc fnc,
153 			   void *fnc_handle)
154 {
155 	const struct v4l2_bt_timings *bt = &t->bt;
156 	const struct v4l2_bt_timings_cap *cap = &dvcap->bt;
157 	u32 caps = cap->capabilities;
158 
159 	if (t->type != V4L2_DV_BT_656_1120)
160 		return false;
161 	if (t->type != dvcap->type ||
162 	    bt->height < cap->min_height ||
163 	    bt->height > cap->max_height ||
164 	    bt->width < cap->min_width ||
165 	    bt->width > cap->max_width ||
166 	    bt->pixelclock < cap->min_pixelclock ||
167 	    bt->pixelclock > cap->max_pixelclock ||
168 	    (cap->standards && bt->standards &&
169 	     !(bt->standards & cap->standards)) ||
170 	    (bt->interlaced && !(caps & V4L2_DV_BT_CAP_INTERLACED)) ||
171 	    (!bt->interlaced && !(caps & V4L2_DV_BT_CAP_PROGRESSIVE)))
172 		return false;
173 	return fnc == NULL || fnc(t, fnc_handle);
174 }
175 EXPORT_SYMBOL_GPL(v4l2_valid_dv_timings);
176 
177 int v4l2_enum_dv_timings_cap(struct v4l2_enum_dv_timings *t,
178 			     const struct v4l2_dv_timings_cap *cap,
179 			     v4l2_check_dv_timings_fnc fnc,
180 			     void *fnc_handle)
181 {
182 	u32 i, idx;
183 
184 	memset(t->reserved, 0, sizeof(t->reserved));
185 	for (i = idx = 0; v4l2_dv_timings_presets[i].bt.width; i++) {
186 		if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
187 					  fnc, fnc_handle) &&
188 		    idx++ == t->index) {
189 			t->timings = v4l2_dv_timings_presets[i];
190 			return 0;
191 		}
192 	}
193 	return -EINVAL;
194 }
195 EXPORT_SYMBOL_GPL(v4l2_enum_dv_timings_cap);
196 
197 bool v4l2_find_dv_timings_cap(struct v4l2_dv_timings *t,
198 			      const struct v4l2_dv_timings_cap *cap,
199 			      unsigned pclock_delta,
200 			      v4l2_check_dv_timings_fnc fnc,
201 			      void *fnc_handle)
202 {
203 	int i;
204 
205 	if (!v4l2_valid_dv_timings(t, cap, fnc, fnc_handle))
206 		return false;
207 
208 	for (i = 0; i < v4l2_dv_timings_presets[i].bt.width; i++) {
209 		if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
210 					  fnc, fnc_handle) &&
211 		    v4l2_match_dv_timings(t, v4l2_dv_timings_presets + i,
212 					  pclock_delta)) {
213 			*t = v4l2_dv_timings_presets[i];
214 			return true;
215 		}
216 	}
217 	return false;
218 }
219 EXPORT_SYMBOL_GPL(v4l2_find_dv_timings_cap);
220 
221 /**
222  * v4l2_match_dv_timings - check if two timings match
223  * @t1 - compare this v4l2_dv_timings struct...
224  * @t2 - with this struct.
225  * @pclock_delta - the allowed pixelclock deviation.
226  *
227  * Compare t1 with t2 with a given margin of error for the pixelclock.
228  */
229 bool v4l2_match_dv_timings(const struct v4l2_dv_timings *t1,
230 			   const struct v4l2_dv_timings *t2,
231 			   unsigned pclock_delta)
232 {
233 	if (t1->type != t2->type || t1->type != V4L2_DV_BT_656_1120)
234 		return false;
235 	if (t1->bt.width == t2->bt.width &&
236 	    t1->bt.height == t2->bt.height &&
237 	    t1->bt.interlaced == t2->bt.interlaced &&
238 	    t1->bt.polarities == t2->bt.polarities &&
239 	    t1->bt.pixelclock >= t2->bt.pixelclock - pclock_delta &&
240 	    t1->bt.pixelclock <= t2->bt.pixelclock + pclock_delta &&
241 	    t1->bt.hfrontporch == t2->bt.hfrontporch &&
242 	    t1->bt.vfrontporch == t2->bt.vfrontporch &&
243 	    t1->bt.vsync == t2->bt.vsync &&
244 	    t1->bt.vbackporch == t2->bt.vbackporch &&
245 	    (!t1->bt.interlaced ||
246 		(t1->bt.il_vfrontporch == t2->bt.il_vfrontporch &&
247 		 t1->bt.il_vsync == t2->bt.il_vsync &&
248 		 t1->bt.il_vbackporch == t2->bt.il_vbackporch)))
249 		return true;
250 	return false;
251 }
252 EXPORT_SYMBOL_GPL(v4l2_match_dv_timings);
253 
254 void v4l2_print_dv_timings(const char *dev_prefix, const char *prefix,
255 			   const struct v4l2_dv_timings *t, bool detailed)
256 {
257 	const struct v4l2_bt_timings *bt = &t->bt;
258 	u32 htot, vtot;
259 
260 	if (t->type != V4L2_DV_BT_656_1120)
261 		return;
262 
263 	htot = V4L2_DV_BT_FRAME_WIDTH(bt);
264 	vtot = V4L2_DV_BT_FRAME_HEIGHT(bt);
265 	if (bt->interlaced)
266 		vtot /= 2;
267 
268 	if (prefix == NULL)
269 		prefix = "";
270 
271 	pr_info("%s: %s%ux%u%s%u (%ux%u)\n", dev_prefix, prefix,
272 		bt->width, bt->height, bt->interlaced ? "i" : "p",
273 		(htot * vtot) > 0 ? ((u32)bt->pixelclock / (htot * vtot)) : 0,
274 		htot, vtot);
275 
276 	if (!detailed)
277 		return;
278 
279 	pr_info("%s: horizontal: fp = %u, %ssync = %u, bp = %u\n",
280 			dev_prefix, bt->hfrontporch,
281 			(bt->polarities & V4L2_DV_HSYNC_POS_POL) ? "+" : "-",
282 			bt->hsync, bt->hbackporch);
283 	pr_info("%s: vertical: fp = %u, %ssync = %u, bp = %u\n",
284 			dev_prefix, bt->vfrontporch,
285 			(bt->polarities & V4L2_DV_VSYNC_POS_POL) ? "+" : "-",
286 			bt->vsync, bt->vbackporch);
287 	if (bt->interlaced)
288 		pr_info("%s: vertical bottom field: fp = %u, %ssync = %u, bp = %u\n",
289 			dev_prefix, bt->il_vfrontporch,
290 			(bt->polarities & V4L2_DV_VSYNC_POS_POL) ? "+" : "-",
291 			bt->il_vsync, bt->il_vbackporch);
292 	pr_info("%s: pixelclock: %llu\n", dev_prefix, bt->pixelclock);
293 	pr_info("%s: flags (0x%x):%s%s%s%s%s\n", dev_prefix, bt->flags,
294 			(bt->flags & V4L2_DV_FL_REDUCED_BLANKING) ?
295 			" REDUCED_BLANKING" : "",
296 			(bt->flags & V4L2_DV_FL_CAN_REDUCE_FPS) ?
297 			" CAN_REDUCE_FPS" : "",
298 			(bt->flags & V4L2_DV_FL_REDUCED_FPS) ?
299 			" REDUCED_FPS" : "",
300 			(bt->flags & V4L2_DV_FL_HALF_LINE) ?
301 			" HALF_LINE" : "",
302 			(bt->flags & V4L2_DV_FL_IS_CE_VIDEO) ?
303 			" CE_VIDEO" : "");
304 	pr_info("%s: standards (0x%x):%s%s%s%s\n", dev_prefix, bt->standards,
305 			(bt->standards & V4L2_DV_BT_STD_CEA861) ?  " CEA" : "",
306 			(bt->standards & V4L2_DV_BT_STD_DMT) ?  " DMT" : "",
307 			(bt->standards & V4L2_DV_BT_STD_CVT) ?  " CVT" : "",
308 			(bt->standards & V4L2_DV_BT_STD_GTF) ?  " GTF" : "");
309 }
310 EXPORT_SYMBOL_GPL(v4l2_print_dv_timings);
311 
312 /*
313  * CVT defines
314  * Based on Coordinated Video Timings Standard
315  * version 1.1 September 10, 2003
316  */
317 
318 #define CVT_PXL_CLK_GRAN	250000	/* pixel clock granularity */
319 
320 /* Normal blanking */
321 #define CVT_MIN_V_BPORCH	7	/* lines */
322 #define CVT_MIN_V_PORCH_RND	3	/* lines */
323 #define CVT_MIN_VSYNC_BP	550	/* min time of vsync + back porch (us) */
324 #define CVT_HSYNC_PERCENT       8       /* nominal hsync as percentage of line */
325 
326 /* Normal blanking for CVT uses GTF to calculate horizontal blanking */
327 #define CVT_CELL_GRAN		8	/* character cell granularity */
328 #define CVT_M			600	/* blanking formula gradient */
329 #define CVT_C			40	/* blanking formula offset */
330 #define CVT_K			128	/* blanking formula scaling factor */
331 #define CVT_J			20	/* blanking formula scaling factor */
332 #define CVT_C_PRIME (((CVT_C - CVT_J) * CVT_K / 256) + CVT_J)
333 #define CVT_M_PRIME (CVT_K * CVT_M / 256)
334 
335 /* Reduced Blanking */
336 #define CVT_RB_MIN_V_BPORCH    7       /* lines  */
337 #define CVT_RB_V_FPORCH        3       /* lines  */
338 #define CVT_RB_MIN_V_BLANK   460     /* us     */
339 #define CVT_RB_H_SYNC         32       /* pixels */
340 #define CVT_RB_H_BPORCH       80       /* pixels */
341 #define CVT_RB_H_BLANK       160       /* pixels */
342 
343 /** v4l2_detect_cvt - detect if the given timings follow the CVT standard
344  * @frame_height - the total height of the frame (including blanking) in lines.
345  * @hfreq - the horizontal frequency in Hz.
346  * @vsync - the height of the vertical sync in lines.
347  * @polarities - the horizontal and vertical polarities (same as struct
348  *		v4l2_bt_timings polarities).
349  * @interlaced - if this flag is true, it indicates interlaced format
350  * @fmt - the resulting timings.
351  *
352  * This function will attempt to detect if the given values correspond to a
353  * valid CVT format. If so, then it will return true, and fmt will be filled
354  * in with the found CVT timings.
355  *
356  * TODO: VESA defined a new version 2 of their reduced blanking
357  * formula. Support for that is currently missing in this CVT
358  * detection function.
359  */
360 bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
361 		u32 polarities, bool interlaced, struct v4l2_dv_timings *fmt)
362 {
363 	int  v_fp, v_bp, h_fp, h_bp, hsync;
364 	int  frame_width, image_height, image_width;
365 	bool reduced_blanking;
366 	unsigned pix_clk;
367 
368 	if (vsync < 4 || vsync > 7)
369 		return false;
370 
371 	if (polarities == V4L2_DV_VSYNC_POS_POL)
372 		reduced_blanking = false;
373 	else if (polarities == V4L2_DV_HSYNC_POS_POL)
374 		reduced_blanking = true;
375 	else
376 		return false;
377 
378 	if (hfreq == 0)
379 		return false;
380 
381 	/* Vertical */
382 	if (reduced_blanking) {
383 		v_fp = CVT_RB_V_FPORCH;
384 		v_bp = (CVT_RB_MIN_V_BLANK * hfreq) / 1000000 + 1;
385 		v_bp -= vsync + v_fp;
386 
387 		if (v_bp < CVT_RB_MIN_V_BPORCH)
388 			v_bp = CVT_RB_MIN_V_BPORCH;
389 	} else {
390 		v_fp = CVT_MIN_V_PORCH_RND;
391 		v_bp = (CVT_MIN_VSYNC_BP * hfreq) / 1000000 + 1 - vsync;
392 
393 		if (v_bp < CVT_MIN_V_BPORCH)
394 			v_bp = CVT_MIN_V_BPORCH;
395 	}
396 
397 	if (interlaced)
398 		image_height = (frame_height - 2 * v_fp - 2 * vsync - 2 * v_bp) & ~0x1;
399 	else
400 		image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;
401 
402 	if (image_height < 0)
403 		return false;
404 
405 	/* Aspect ratio based on vsync */
406 	switch (vsync) {
407 	case 4:
408 		image_width = (image_height * 4) / 3;
409 		break;
410 	case 5:
411 		image_width = (image_height * 16) / 9;
412 		break;
413 	case 6:
414 		image_width = (image_height * 16) / 10;
415 		break;
416 	case 7:
417 		/* special case */
418 		if (image_height == 1024)
419 			image_width = (image_height * 5) / 4;
420 		else if (image_height == 768)
421 			image_width = (image_height * 15) / 9;
422 		else
423 			return false;
424 		break;
425 	default:
426 		return false;
427 	}
428 
429 	image_width = image_width & ~7;
430 
431 	/* Horizontal */
432 	if (reduced_blanking) {
433 		pix_clk = (image_width + CVT_RB_H_BLANK) * hfreq;
434 		pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;
435 
436 		h_bp = CVT_RB_H_BPORCH;
437 		hsync = CVT_RB_H_SYNC;
438 		h_fp = CVT_RB_H_BLANK - h_bp - hsync;
439 
440 		frame_width = image_width + CVT_RB_H_BLANK;
441 	} else {
442 		unsigned ideal_duty_cycle_per_myriad =
443 			100 * CVT_C_PRIME - (CVT_M_PRIME * 100000) / hfreq;
444 		int h_blank;
445 
446 		if (ideal_duty_cycle_per_myriad < 2000)
447 			ideal_duty_cycle_per_myriad = 2000;
448 
449 		h_blank = image_width * ideal_duty_cycle_per_myriad /
450 					(10000 - ideal_duty_cycle_per_myriad);
451 		h_blank = (h_blank / (2 * CVT_CELL_GRAN)) * 2 * CVT_CELL_GRAN;
452 
453 		pix_clk = (image_width + h_blank) * hfreq;
454 		pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;
455 
456 		h_bp = h_blank / 2;
457 		frame_width = image_width + h_blank;
458 
459 		hsync = frame_width * CVT_HSYNC_PERCENT / 100;
460 		hsync = (hsync / CVT_CELL_GRAN) * CVT_CELL_GRAN;
461 		h_fp = h_blank - hsync - h_bp;
462 	}
463 
464 	fmt->type = V4L2_DV_BT_656_1120;
465 	fmt->bt.polarities = polarities;
466 	fmt->bt.width = image_width;
467 	fmt->bt.height = image_height;
468 	fmt->bt.hfrontporch = h_fp;
469 	fmt->bt.vfrontporch = v_fp;
470 	fmt->bt.hsync = hsync;
471 	fmt->bt.vsync = vsync;
472 	fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
473 
474 	if (!interlaced) {
475 		fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
476 		fmt->bt.interlaced = V4L2_DV_PROGRESSIVE;
477 	} else {
478 		fmt->bt.vbackporch = (frame_height - image_height - 2 * v_fp -
479 				      2 * vsync) / 2;
480 		fmt->bt.il_vbackporch = frame_height - image_height - 2 * v_fp -
481 					2 * vsync - fmt->bt.vbackporch;
482 		fmt->bt.il_vfrontporch = v_fp;
483 		fmt->bt.il_vsync = vsync;
484 		fmt->bt.flags |= V4L2_DV_FL_HALF_LINE;
485 		fmt->bt.interlaced = V4L2_DV_INTERLACED;
486 	}
487 
488 	fmt->bt.pixelclock = pix_clk;
489 	fmt->bt.standards = V4L2_DV_BT_STD_CVT;
490 
491 	if (reduced_blanking)
492 		fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
493 
494 	return true;
495 }
496 EXPORT_SYMBOL_GPL(v4l2_detect_cvt);
497 
498 /*
499  * GTF defines
500  * Based on Generalized Timing Formula Standard
501  * Version 1.1 September 2, 1999
502  */
503 
504 #define GTF_PXL_CLK_GRAN	250000	/* pixel clock granularity */
505 
506 #define GTF_MIN_VSYNC_BP	550	/* min time of vsync + back porch (us) */
507 #define GTF_V_FP		1	/* vertical front porch (lines) */
508 #define GTF_CELL_GRAN		8	/* character cell granularity */
509 
510 /* Default */
511 #define GTF_D_M			600	/* blanking formula gradient */
512 #define GTF_D_C			40	/* blanking formula offset */
513 #define GTF_D_K			128	/* blanking formula scaling factor */
514 #define GTF_D_J			20	/* blanking formula scaling factor */
515 #define GTF_D_C_PRIME ((((GTF_D_C - GTF_D_J) * GTF_D_K) / 256) + GTF_D_J)
516 #define GTF_D_M_PRIME ((GTF_D_K * GTF_D_M) / 256)
517 
518 /* Secondary */
519 #define GTF_S_M			3600	/* blanking formula gradient */
520 #define GTF_S_C			40	/* blanking formula offset */
521 #define GTF_S_K			128	/* blanking formula scaling factor */
522 #define GTF_S_J			35	/* blanking formula scaling factor */
523 #define GTF_S_C_PRIME ((((GTF_S_C - GTF_S_J) * GTF_S_K) / 256) + GTF_S_J)
524 #define GTF_S_M_PRIME ((GTF_S_K * GTF_S_M) / 256)
525 
526 /** v4l2_detect_gtf - detect if the given timings follow the GTF standard
527  * @frame_height - the total height of the frame (including blanking) in lines.
528  * @hfreq - the horizontal frequency in Hz.
529  * @vsync - the height of the vertical sync in lines.
530  * @polarities - the horizontal and vertical polarities (same as struct
531  *		v4l2_bt_timings polarities).
532  * @interlaced - if this flag is true, it indicates interlaced format
533  * @aspect - preferred aspect ratio. GTF has no method of determining the
534  *		aspect ratio in order to derive the image width from the
535  *		image height, so it has to be passed explicitly. Usually
536  *		the native screen aspect ratio is used for this. If it
537  *		is not filled in correctly, then 16:9 will be assumed.
538  * @fmt - the resulting timings.
539  *
540  * This function will attempt to detect if the given values correspond to a
541  * valid GTF format. If so, then it will return true, and fmt will be filled
542  * in with the found GTF timings.
543  */
544 bool v4l2_detect_gtf(unsigned frame_height,
545 		unsigned hfreq,
546 		unsigned vsync,
547 		u32 polarities,
548 		bool interlaced,
549 		struct v4l2_fract aspect,
550 		struct v4l2_dv_timings *fmt)
551 {
552 	int pix_clk;
553 	int  v_fp, v_bp, h_fp, hsync;
554 	int frame_width, image_height, image_width;
555 	bool default_gtf;
556 	int h_blank;
557 
558 	if (vsync != 3)
559 		return false;
560 
561 	if (polarities == V4L2_DV_VSYNC_POS_POL)
562 		default_gtf = true;
563 	else if (polarities == V4L2_DV_HSYNC_POS_POL)
564 		default_gtf = false;
565 	else
566 		return false;
567 
568 	if (hfreq == 0)
569 		return false;
570 
571 	/* Vertical */
572 	v_fp = GTF_V_FP;
573 	v_bp = (GTF_MIN_VSYNC_BP * hfreq + 500000) / 1000000 - vsync;
574 	if (interlaced)
575 		image_height = (frame_height - 2 * v_fp - 2 * vsync - 2 * v_bp) & ~0x1;
576 	else
577 		image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;
578 
579 	if (image_height < 0)
580 		return false;
581 
582 	if (aspect.numerator == 0 || aspect.denominator == 0) {
583 		aspect.numerator = 16;
584 		aspect.denominator = 9;
585 	}
586 	image_width = ((image_height * aspect.numerator) / aspect.denominator);
587 	image_width = (image_width + GTF_CELL_GRAN/2) & ~(GTF_CELL_GRAN - 1);
588 
589 	/* Horizontal */
590 	if (default_gtf) {
591 		u64 num;
592 		u32 den;
593 
594 		num = ((image_width * GTF_D_C_PRIME * (u64)hfreq) -
595 		      ((u64)image_width * GTF_D_M_PRIME * 1000));
596 		den = (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000) *
597 		      (2 * GTF_CELL_GRAN);
598 		h_blank = div_u64((num + (den >> 1)), den);
599 		h_blank *= (2 * GTF_CELL_GRAN);
600 	} else {
601 		u64 num;
602 		u32 den;
603 
604 		num = ((image_width * GTF_S_C_PRIME * (u64)hfreq) -
605 		      ((u64)image_width * GTF_S_M_PRIME * 1000));
606 		den = (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000) *
607 		      (2 * GTF_CELL_GRAN);
608 		h_blank = div_u64((num + (den >> 1)), den);
609 		h_blank *= (2 * GTF_CELL_GRAN);
610 	}
611 
612 	frame_width = image_width + h_blank;
613 
614 	pix_clk = (image_width + h_blank) * hfreq;
615 	pix_clk = pix_clk / GTF_PXL_CLK_GRAN * GTF_PXL_CLK_GRAN;
616 
617 	hsync = (frame_width * 8 + 50) / 100;
618 	hsync = ((hsync + GTF_CELL_GRAN / 2) / GTF_CELL_GRAN) * GTF_CELL_GRAN;
619 
620 	h_fp = h_blank / 2 - hsync;
621 
622 	fmt->type = V4L2_DV_BT_656_1120;
623 	fmt->bt.polarities = polarities;
624 	fmt->bt.width = image_width;
625 	fmt->bt.height = image_height;
626 	fmt->bt.hfrontporch = h_fp;
627 	fmt->bt.vfrontporch = v_fp;
628 	fmt->bt.hsync = hsync;
629 	fmt->bt.vsync = vsync;
630 	fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
631 
632 	if (!interlaced) {
633 		fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
634 		fmt->bt.interlaced = V4L2_DV_PROGRESSIVE;
635 	} else {
636 		fmt->bt.vbackporch = (frame_height - image_height - 2 * v_fp -
637 				      2 * vsync) / 2;
638 		fmt->bt.il_vbackporch = frame_height - image_height - 2 * v_fp -
639 					2 * vsync - fmt->bt.vbackporch;
640 		fmt->bt.il_vfrontporch = v_fp;
641 		fmt->bt.il_vsync = vsync;
642 		fmt->bt.flags |= V4L2_DV_FL_HALF_LINE;
643 		fmt->bt.interlaced = V4L2_DV_INTERLACED;
644 	}
645 
646 	fmt->bt.pixelclock = pix_clk;
647 	fmt->bt.standards = V4L2_DV_BT_STD_GTF;
648 
649 	if (!default_gtf)
650 		fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
651 
652 	return true;
653 }
654 EXPORT_SYMBOL_GPL(v4l2_detect_gtf);
655 
656 /** v4l2_calc_aspect_ratio - calculate the aspect ratio based on bytes
657  *	0x15 and 0x16 from the EDID.
658  * @hor_landscape - byte 0x15 from the EDID.
659  * @vert_portrait - byte 0x16 from the EDID.
660  *
661  * Determines the aspect ratio from the EDID.
662  * See VESA Enhanced EDID standard, release A, rev 2, section 3.6.2:
663  * "Horizontal and Vertical Screen Size or Aspect Ratio"
664  */
665 struct v4l2_fract v4l2_calc_aspect_ratio(u8 hor_landscape, u8 vert_portrait)
666 {
667 	struct v4l2_fract aspect = { 16, 9 };
668 	u32 tmp;
669 	u8 ratio;
670 
671 	/* Nothing filled in, fallback to 16:9 */
672 	if (!hor_landscape && !vert_portrait)
673 		return aspect;
674 	/* Both filled in, so they are interpreted as the screen size in cm */
675 	if (hor_landscape && vert_portrait) {
676 		aspect.numerator = hor_landscape;
677 		aspect.denominator = vert_portrait;
678 		return aspect;
679 	}
680 	/* Only one is filled in, so interpret them as a ratio:
681 	   (val + 99) / 100 */
682 	ratio = hor_landscape | vert_portrait;
683 	/* Change some rounded values into the exact aspect ratio */
684 	if (ratio == 79) {
685 		aspect.numerator = 16;
686 		aspect.denominator = 9;
687 	} else if (ratio == 34) {
688 		aspect.numerator = 4;
689 		aspect.denominator = 3;
690 	} else if (ratio == 68) {
691 		aspect.numerator = 15;
692 		aspect.denominator = 9;
693 	} else {
694 		aspect.numerator = hor_landscape + 99;
695 		aspect.denominator = 100;
696 	}
697 	if (hor_landscape)
698 		return aspect;
699 	/* The aspect ratio is for portrait, so swap numerator and denominator */
700 	tmp = aspect.denominator;
701 	aspect.denominator = aspect.numerator;
702 	aspect.numerator = tmp;
703 	return aspect;
704 }
705 EXPORT_SYMBOL_GPL(v4l2_calc_aspect_ratio);
706