xref: /openbmc/qemu/hw/display/edid-generate.c (revision 6a094d62) 
1 /*
2  * QEMU EDID generator.
3  *
4  * This work is licensed under the terms of the GNU GPL, version 2 or later.
5  * See the COPYING file in the top-level directory.
6  */
7 #include "qemu/osdep.h"
8 #include "qemu/bswap.h"
9 #include "hw/display/edid.h"
10 
11 static const struct edid_mode {
12     uint32_t xres;
13     uint32_t yres;
14     uint32_t byte;
15     uint32_t xtra3;
16     uint32_t bit;
17     uint32_t dta;
18 } modes[] = {
19     /* dea/dta extension timings (all @ 50 Hz) */
20     { .xres = 5120,   .yres = 2160,   .dta = 125 },
21     { .xres = 4096,   .yres = 2160,   .dta = 101 },
22     { .xres = 3840,   .yres = 2160,   .dta =  96 },
23     { .xres = 2560,   .yres = 1080,   .dta =  89 },
24     { .xres = 2048,   .yres = 1152 },
25     { .xres = 1920,   .yres = 1080,   .dta =  31 },
26 
27     /* dea/dta extension timings (all @ 60 Hz) */
28     { .xres = 3840,   .yres = 2160,   .dta =  97 },
29 
30     /* additional standard timings 3 (all @ 60Hz) */
31     { .xres = 1920,   .yres = 1200,   .xtra3 = 10,   .bit = 0 },
32     { .xres = 1600,   .yres = 1200,   .xtra3 =  9,   .bit = 2 },
33     { .xres = 1680,   .yres = 1050,   .xtra3 =  9,   .bit = 5 },
34     { .xres = 1440,   .yres =  900,   .xtra3 =  8,   .bit = 5 },
35     { .xres = 1280,   .yres = 1024,   .xtra3 =  7,   .bit = 1 },
36     { .xres = 1280,   .yres =  960,   .xtra3 =  7,   .bit = 3 },
37     { .xres = 1280,   .yres =  768,   .xtra3 =  7,   .bit = 6 },
38 
39     { .xres = 1920,   .yres = 1440,   .xtra3 = 11,   .bit = 5 },
40     { .xres = 1856,   .yres = 1392,   .xtra3 = 10,   .bit = 3 },
41     { .xres = 1792,   .yres = 1344,   .xtra3 = 10,   .bit = 5 },
42     { .xres = 1440,   .yres = 1050,   .xtra3 =  8,   .bit = 1 },
43     { .xres = 1360,   .yres =  768,   .xtra3 =  8,   .bit = 7 },
44 
45     /* established timings (all @ 60Hz) */
46     { .xres = 1024,   .yres =  768,   .byte  = 36,   .bit = 3 },
47     { .xres =  800,   .yres =  600,   .byte  = 35,   .bit = 0 },
48     { .xres =  640,   .yres =  480,   .byte  = 35,   .bit = 5 },
49 };
50 
51 typedef struct Timings {
52     uint32_t xfront;
53     uint32_t xsync;
54     uint32_t xblank;
55 
56     uint32_t yfront;
57     uint32_t ysync;
58     uint32_t yblank;
59 
60     uint64_t clock;
61 } Timings;
62 
63 static void generate_timings(Timings *timings, uint32_t refresh_rate,
64                              uint32_t xres, uint32_t yres)
65 {
66     /* pull some realistic looking timings out of thin air */
67     timings->xfront = xres * 25 / 100;
68     timings->xsync  = xres *  3 / 100;
69     timings->xblank = xres * 35 / 100;
70 
71     timings->yfront = yres *  5 / 1000;
72     timings->ysync  = yres *  5 / 1000;
73     timings->yblank = yres * 35 / 1000;
74 
75     timings->clock  = ((uint64_t)refresh_rate *
76                        (xres + timings->xblank) *
77                        (yres + timings->yblank)) / 10000000;
78 }
79 
80 static void edid_ext_dta(uint8_t *dta)
81 {
82     dta[0] = 0x02;
83     dta[1] = 0x03;
84     dta[2] = 0x05;
85     dta[3] = 0x00;
86 
87     /* video data block */
88     dta[4] = 0x40;
89 }
90 
91 static void edid_ext_dta_mode(uint8_t *dta, uint8_t nr)
92 {
93     dta[dta[2]] = nr;
94     dta[2]++;
95     dta[4]++;
96 }
97 
98 static int edid_std_mode(uint8_t *mode, uint32_t xres, uint32_t yres)
99 {
100     uint32_t aspect;
101 
102     if (xres == 0 || yres == 0) {
103         mode[0] = 0x01;
104         mode[1] = 0x01;
105         return 0;
106 
107     } else if (xres * 10 == yres * 16) {
108         aspect = 0;
109     } else if (xres * 3 == yres * 4) {
110         aspect = 1;
111     } else if (xres * 4 == yres * 5) {
112         aspect = 2;
113     } else if (xres * 9 == yres * 16) {
114         aspect = 3;
115     } else {
116         return -1;
117     }
118 
119     if ((xres / 8) - 31 > 255) {
120         return -1;
121     }
122 
123     mode[0] = (xres / 8) - 31;
124     mode[1] = ((aspect << 6) | (60 - 60));
125     return 0;
126 }
127 
128 static void edid_fill_modes(uint8_t *edid, uint8_t *xtra3, uint8_t *dta,
129                             uint32_t maxx, uint32_t maxy)
130 {
131     const struct edid_mode *mode;
132     int std = 38;
133     int rc, i;
134 
135     for (i = 0; i < ARRAY_SIZE(modes); i++) {
136         mode = modes + i;
137 
138         if ((maxx && mode->xres > maxx) ||
139             (maxy && mode->yres > maxy)) {
140             continue;
141         }
142 
143         if (mode->byte) {
144             edid[mode->byte] |= (1 << mode->bit);
145         } else if (std < 54) {
146             rc = edid_std_mode(edid + std, mode->xres, mode->yres);
147             if (rc == 0) {
148                 std += 2;
149             }
150         } else if (mode->xtra3 && xtra3) {
151             xtra3[mode->xtra3] |= (1 << mode->bit);
152         }
153 
154         if (dta && mode->dta) {
155             edid_ext_dta_mode(dta, mode->dta);
156         }
157     }
158 
159     while (std < 54) {
160         edid_std_mode(edid + std, 0, 0);
161         std += 2;
162     }
163 }
164 
165 static void edid_checksum(uint8_t *edid, size_t len)
166 {
167     uint32_t sum = 0;
168     int i;
169 
170     for (i = 0; i < len; i++) {
171         sum += edid[i];
172     }
173     sum &= 0xff;
174     if (sum) {
175         edid[len] = 0x100 - sum;
176     }
177 }
178 
179 static uint8_t *edid_desc_next(uint8_t *edid, uint8_t *dta, uint8_t *desc)
180 {
181     if (desc == NULL) {
182         return NULL;
183     }
184     if (desc + 18 + 18 < edid + 127) {
185         return desc + 18;
186     }
187     if (dta) {
188         if (desc < edid + 127) {
189             return dta + dta[2];
190         }
191         if (desc + 18 + 18 < dta + 127) {
192             return desc + 18;
193         }
194     }
195     return NULL;
196 }
197 
198 static void edid_desc_type(uint8_t *desc, uint8_t type)
199 {
200     desc[0] = 0;
201     desc[1] = 0;
202     desc[2] = 0;
203     desc[3] = type;
204     desc[4] = 0;
205 }
206 
207 static void edid_desc_text(uint8_t *desc, uint8_t type,
208                            const char *text)
209 {
210     size_t len;
211 
212     edid_desc_type(desc, type);
213     memset(desc + 5, ' ', 13);
214 
215     len = strlen(text);
216     if (len > 12) {
217         len = 12;
218     }
219     memcpy(desc + 5, text, len);
220     desc[5 + len] = '\n';
221 }
222 
223 static void edid_desc_ranges(uint8_t *desc)
224 {
225     edid_desc_type(desc, 0xfd);
226 
227     /* vertical (50 -> 125 Hz) */
228     desc[5] =  50;
229     desc[6] = 125;
230 
231     /* horizontal (30 -> 160 kHz) */
232     desc[7] =  30;
233     desc[8] = 160;
234 
235     /* max dot clock (2550 MHz) */
236     desc[9] = 2550 / 10;
237 
238     /* no extended timing information */
239     desc[10] = 0x01;
240 
241     /* padding */
242     desc[11] = '\n';
243     memset(desc + 12, ' ', 6);
244 }
245 
246 /* additional standard timings 3 */
247 static void edid_desc_xtra3_std(uint8_t *desc)
248 {
249     edid_desc_type(desc, 0xf7);
250     desc[5] = 10;
251 }
252 
253 static void edid_desc_dummy(uint8_t *desc)
254 {
255     edid_desc_type(desc, 0x10);
256 }
257 
258 static void edid_desc_timing(uint8_t *desc, uint32_t refresh_rate,
259                              uint32_t xres, uint32_t yres,
260                              uint32_t xmm, uint32_t ymm)
261 {
262     Timings timings;
263     generate_timings(&timings, refresh_rate, xres, yres);
264     stl_le_p(desc, timings.clock);
265 
266     desc[2] = xres   & 0xff;
267     desc[3] = timings.xblank & 0xff;
268     desc[4] = (((xres   & 0xf00) >> 4) |
269                ((timings.xblank & 0xf00) >> 8));
270 
271     desc[5] = yres   & 0xff;
272     desc[6] = timings.yblank & 0xff;
273     desc[7] = (((yres   & 0xf00) >> 4) |
274                ((timings.yblank & 0xf00) >> 8));
275 
276     desc[8] = timings.xfront & 0xff;
277     desc[9] = timings.xsync  & 0xff;
278 
279     desc[10] = (((timings.yfront & 0x00f) << 4) |
280                 ((timings.ysync  & 0x00f) << 0));
281     desc[11] = (((timings.xfront & 0x300) >> 2) |
282                 ((timings.xsync  & 0x300) >> 4) |
283                 ((timings.yfront & 0x030) >> 2) |
284                 ((timings.ysync  & 0x030) >> 4));
285 
286     desc[12] = xmm & 0xff;
287     desc[13] = ymm & 0xff;
288     desc[14] = (((xmm & 0xf00) >> 4) |
289                 ((ymm & 0xf00) >> 8));
290 
291     desc[17] = 0x18;
292 }
293 
294 static uint32_t edid_to_10bit(float value)
295 {
296     return (uint32_t)(value * 1024 + 0.5);
297 }
298 
299 static void edid_colorspace(uint8_t *edid,
300                             float rx, float ry,
301                             float gx, float gy,
302                             float bx, float by,
303                             float wx, float wy)
304 {
305     uint32_t red_x   = edid_to_10bit(rx);
306     uint32_t red_y   = edid_to_10bit(ry);
307     uint32_t green_x = edid_to_10bit(gx);
308     uint32_t green_y = edid_to_10bit(gy);
309     uint32_t blue_x  = edid_to_10bit(bx);
310     uint32_t blue_y  = edid_to_10bit(by);
311     uint32_t white_x = edid_to_10bit(wx);
312     uint32_t white_y = edid_to_10bit(wy);
313 
314     edid[25] = (((red_x   & 0x03) << 6) |
315                 ((red_y   & 0x03) << 4) |
316                 ((green_x & 0x03) << 2) |
317                 ((green_y & 0x03) << 0));
318     edid[26] = (((blue_x  & 0x03) << 6) |
319                 ((blue_y  & 0x03) << 4) |
320                 ((white_x & 0x03) << 2) |
321                 ((white_y & 0x03) << 0));
322     edid[27] = red_x   >> 2;
323     edid[28] = red_y   >> 2;
324     edid[29] = green_x >> 2;
325     edid[30] = green_y >> 2;
326     edid[31] = blue_x  >> 2;
327     edid[32] = blue_y  >> 2;
328     edid[33] = white_x >> 2;
329     edid[34] = white_y >> 2;
330 }
331 
332 static uint32_t qemu_edid_dpi_from_mm(uint32_t mm, uint32_t res)
333 {
334     return res * 254 / 10 / mm;
335 }
336 
337 uint32_t qemu_edid_dpi_to_mm(uint32_t dpi, uint32_t res)
338 {
339     return res * 254 / 10 / dpi;
340 }
341 
342 static void init_displayid(uint8_t *did)
343 {
344     did[0] = 0x70; /* display id extension */
345     did[1] = 0x13; /* version 1.3 */
346     did[2] = 4;    /* length */
347     did[3] = 0x03; /* product type (0x03 == standalone display device) */
348     edid_checksum(did + 1, did[2] + 4);
349 }
350 
351 static void qemu_displayid_generate(uint8_t *did, uint32_t refresh_rate,
352                                     uint32_t xres, uint32_t yres,
353                                     uint32_t xmm, uint32_t ymm)
354 {
355     Timings timings;
356     generate_timings(&timings, refresh_rate, xres, yres);
357 
358     did[0] = 0x70; /* display id extension */
359     did[1] = 0x13; /* version 1.3 */
360     did[2] = 23;   /* length */
361     did[3] = 0x03; /* product type (0x03 == standalone display device) */
362 
363     did[5] = 0x03; /* Detailed Timings Data Block */
364     did[6] = 0x00; /* revision */
365     did[7] = 0x14; /* block length */
366 
367     did[8]  = timings.clock  & 0xff;
368     did[9]  = (timings.clock & 0xff00) >> 8;
369     did[10] = (timings.clock & 0xff0000) >> 16;
370 
371     did[11] = 0x88; /* leave aspect ratio undefined */
372 
373     stw_le_p(did + 12, 0xffff & (xres - 1));
374     stw_le_p(did + 14, 0xffff & (timings.xblank - 1));
375     stw_le_p(did + 16, 0xffff & (timings.xfront - 1));
376     stw_le_p(did + 18, 0xffff & (timings.xsync - 1));
377 
378     stw_le_p(did + 20, 0xffff & (yres - 1));
379     stw_le_p(did + 22, 0xffff & (timings.yblank - 1));
380     stw_le_p(did + 24, 0xffff & (timings.yfront - 1));
381     stw_le_p(did + 26, 0xffff & (timings.ysync - 1));
382 
383     edid_checksum(did + 1, did[2] + 4);
384 }
385 
386 void qemu_edid_generate(uint8_t *edid, size_t size,
387                         qemu_edid_info *info)
388 {
389     uint8_t *desc = edid + 54;
390     uint8_t *xtra3 = NULL;
391     uint8_t *dta = NULL;
392     uint8_t *did = NULL;
393     uint32_t width_mm, height_mm;
394     uint32_t refresh_rate = info->refresh_rate ? info->refresh_rate : 75000;
395     uint32_t dpi = 100; /* if no width_mm/height_mm */
396     uint32_t large_screen = 0;
397 
398     /* =============== set defaults  =============== */
399 
400     if (!info->vendor || strlen(info->vendor) != 3) {
401         info->vendor = "RHT";
402     }
403     if (!info->name) {
404         info->name = "QEMU Monitor";
405     }
406     if (!info->prefx) {
407         info->prefx = 1280;
408     }
409     if (!info->prefy) {
410         info->prefy = 800;
411     }
412     if (info->prefx >= 4096 || info->prefy >= 4096) {
413         large_screen = 1;
414     }
415     if (info->width_mm && info->height_mm) {
416         width_mm = info->width_mm;
417         height_mm = info->height_mm;
418         dpi = qemu_edid_dpi_from_mm(width_mm, info->prefx);
419     } else {
420         width_mm = qemu_edid_dpi_to_mm(dpi, info->prefx);
421         height_mm = qemu_edid_dpi_to_mm(dpi, info->prefy);
422     }
423 
424     /* =============== extensions  =============== */
425 
426     if (size >= 256) {
427         dta = edid + 128;
428         edid[126]++;
429         edid_ext_dta(dta);
430     }
431 
432     if (size >= 384 && large_screen) {
433         did = edid + 256;
434         edid[126]++;
435         init_displayid(did);
436     }
437 
438     /* =============== header information =============== */
439 
440     /* fixed */
441     edid[0] = 0x00;
442     edid[1] = 0xff;
443     edid[2] = 0xff;
444     edid[3] = 0xff;
445     edid[4] = 0xff;
446     edid[5] = 0xff;
447     edid[6] = 0xff;
448     edid[7] = 0x00;
449 
450     /* manufacturer id, product code, serial number */
451     uint16_t vendor_id = ((((info->vendor[0] - '@') & 0x1f) << 10) |
452                           (((info->vendor[1] - '@') & 0x1f) <<  5) |
453                           (((info->vendor[2] - '@') & 0x1f) <<  0));
454     uint16_t model_nr = 0x1234;
455     uint32_t serial_nr = info->serial ? atoi(info->serial) : 0;
456     stw_be_p(edid +  8, vendor_id);
457     stw_le_p(edid + 10, model_nr);
458     stl_le_p(edid + 12, serial_nr);
459 
460     /* manufacture week and year */
461     edid[16] = 42;
462     edid[17] = 2014 - 1990;
463 
464     /* edid version */
465     edid[18] = 1;
466     edid[19] = 4;
467 
468 
469     /* =============== basic display parameters =============== */
470 
471     /* video input: digital, 8bpc, displayport */
472     edid[20] = 0xa5;
473 
474     /* screen size: undefined */
475     edid[21] = width_mm / 10;
476     edid[22] = height_mm / 10;
477 
478     /* display gamma: 2.2 */
479     edid[23] = 220 - 100;
480 
481     /* supported features bitmap: std sRGB, preferred timing */
482     edid[24] = 0x06;
483 
484 
485     /* =============== chromaticity coordinates =============== */
486 
487     /* standard sRGB colorspace */
488     edid_colorspace(edid,
489                     0.6400, 0.3300,   /* red   */
490                     0.3000, 0.6000,   /* green */
491                     0.1500, 0.0600,   /* blue  */
492                     0.3127, 0.3290);  /* white point  */
493 
494     /* =============== established timing bitmap =============== */
495     /* =============== standard timing information =============== */
496 
497     /* both filled by edid_fill_modes() */
498 
499 
500     /* =============== descriptor blocks =============== */
501 
502     if (!large_screen) {
503         /* The DTD section has only 12 bits to store the resolution */
504         edid_desc_timing(desc, refresh_rate, info->prefx, info->prefy,
505                          width_mm, height_mm);
506         desc = edid_desc_next(edid, dta, desc);
507     }
508 
509     xtra3 = desc;
510     edid_desc_xtra3_std(xtra3);
511     desc = edid_desc_next(edid, dta, desc);
512     edid_fill_modes(edid, xtra3, dta, info->maxx, info->maxy);
513     /*
514      * dta video data block is finished at thus point,
515      * so dta descriptor offsets don't move any more.
516      */
517 
518     edid_desc_ranges(desc);
519     desc = edid_desc_next(edid, dta, desc);
520 
521     if (desc && info->name) {
522         edid_desc_text(desc, 0xfc, info->name);
523         desc = edid_desc_next(edid, dta, desc);
524     }
525 
526     if (desc && info->serial) {
527         edid_desc_text(desc, 0xff, info->serial);
528         desc = edid_desc_next(edid, dta, desc);
529     }
530 
531     while (desc) {
532         edid_desc_dummy(desc);
533         desc = edid_desc_next(edid, dta, desc);
534     }
535 
536     /* =============== display id extensions =============== */
537 
538     if (did && large_screen) {
539         qemu_displayid_generate(did, refresh_rate, info->prefx, info->prefy,
540                                 width_mm, height_mm);
541     }
542 
543     /* =============== finish up =============== */
544 
545     edid_checksum(edid, 127);
546     if (dta) {
547         edid_checksum(dta, 127);
548     }
549     if (did) {
550         edid_checksum(did, 127);
551     }
552 }
553 
554 size_t qemu_edid_size(uint8_t *edid)
555 {
556     uint32_t exts;
557 
558     if (edid[0] != 0x00 ||
559         edid[1] != 0xff) {
560         /* doesn't look like a valid edid block */
561         return 0;
562     }
563 
564     exts = edid[126];
565     return 128 * (exts + 1);
566 }
567