xref: /openbmc/qemu/hw/display/edid-generate.c (revision b21e2380) 
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, const Timings *timings,
259                              uint32_t xres, uint32_t yres,
260                              uint32_t xmm, uint32_t ymm)
261 {
262     stw_le_p(desc, timings->clock);
263 
264     desc[2] = xres   & 0xff;
265     desc[3] = timings->xblank & 0xff;
266     desc[4] = (((xres   & 0xf00) >> 4) |
267                ((timings->xblank & 0xf00) >> 8));
268 
269     desc[5] = yres   & 0xff;
270     desc[6] = timings->yblank & 0xff;
271     desc[7] = (((yres   & 0xf00) >> 4) |
272                ((timings->yblank & 0xf00) >> 8));
273 
274     desc[8] = timings->xfront & 0xff;
275     desc[9] = timings->xsync  & 0xff;
276 
277     desc[10] = (((timings->yfront & 0x00f) << 4) |
278                 ((timings->ysync  & 0x00f) << 0));
279     desc[11] = (((timings->xfront & 0x300) >> 2) |
280                 ((timings->xsync  & 0x300) >> 4) |
281                 ((timings->yfront & 0x030) >> 2) |
282                 ((timings->ysync  & 0x030) >> 4));
283 
284     desc[12] = xmm & 0xff;
285     desc[13] = ymm & 0xff;
286     desc[14] = (((xmm & 0xf00) >> 4) |
287                 ((ymm & 0xf00) >> 8));
288 
289     desc[17] = 0x18;
290 }
291 
292 static uint32_t edid_to_10bit(float value)
293 {
294     return (uint32_t)(value * 1024 + 0.5);
295 }
296 
297 static void edid_colorspace(uint8_t *edid,
298                             float rx, float ry,
299                             float gx, float gy,
300                             float bx, float by,
301                             float wx, float wy)
302 {
303     uint32_t red_x   = edid_to_10bit(rx);
304     uint32_t red_y   = edid_to_10bit(ry);
305     uint32_t green_x = edid_to_10bit(gx);
306     uint32_t green_y = edid_to_10bit(gy);
307     uint32_t blue_x  = edid_to_10bit(bx);
308     uint32_t blue_y  = edid_to_10bit(by);
309     uint32_t white_x = edid_to_10bit(wx);
310     uint32_t white_y = edid_to_10bit(wy);
311 
312     edid[25] = (((red_x   & 0x03) << 6) |
313                 ((red_y   & 0x03) << 4) |
314                 ((green_x & 0x03) << 2) |
315                 ((green_y & 0x03) << 0));
316     edid[26] = (((blue_x  & 0x03) << 6) |
317                 ((blue_y  & 0x03) << 4) |
318                 ((white_x & 0x03) << 2) |
319                 ((white_y & 0x03) << 0));
320     edid[27] = red_x   >> 2;
321     edid[28] = red_y   >> 2;
322     edid[29] = green_x >> 2;
323     edid[30] = green_y >> 2;
324     edid[31] = blue_x  >> 2;
325     edid[32] = blue_y  >> 2;
326     edid[33] = white_x >> 2;
327     edid[34] = white_y >> 2;
328 }
329 
330 static uint32_t qemu_edid_dpi_from_mm(uint32_t mm, uint32_t res)
331 {
332     return res * 254 / 10 / mm;
333 }
334 
335 uint32_t qemu_edid_dpi_to_mm(uint32_t dpi, uint32_t res)
336 {
337     return res * 254 / 10 / dpi;
338 }
339 
340 static void init_displayid(uint8_t *did)
341 {
342     did[0] = 0x70; /* display id extension */
343     did[1] = 0x13; /* version 1.3 */
344     did[2] = 4;    /* length */
345     did[3] = 0x03; /* product type (0x03 == standalone display device) */
346     edid_checksum(did + 1, did[2] + 4);
347 }
348 
349 static void qemu_displayid_generate(uint8_t *did, const Timings *timings,
350                                     uint32_t xres, uint32_t yres,
351                                     uint32_t xmm, uint32_t ymm)
352 {
353     did[0] = 0x70; /* display id extension */
354     did[1] = 0x13; /* version 1.3 */
355     did[2] = 23;   /* length */
356     did[3] = 0x03; /* product type (0x03 == standalone display device) */
357 
358     did[5] = 0x03; /* Detailed Timings Data Block */
359     did[6] = 0x00; /* revision */
360     did[7] = 0x14; /* block length */
361 
362     did[8]  = timings->clock  & 0xff;
363     did[9]  = (timings->clock & 0xff00) >> 8;
364     did[10] = (timings->clock & 0xff0000) >> 16;
365 
366     did[11] = 0x88; /* leave aspect ratio undefined */
367 
368     stw_le_p(did + 12, 0xffff & (xres - 1));
369     stw_le_p(did + 14, 0xffff & (timings->xblank - 1));
370     stw_le_p(did + 16, 0xffff & (timings->xfront - 1));
371     stw_le_p(did + 18, 0xffff & (timings->xsync - 1));
372 
373     stw_le_p(did + 20, 0xffff & (yres - 1));
374     stw_le_p(did + 22, 0xffff & (timings->yblank - 1));
375     stw_le_p(did + 24, 0xffff & (timings->yfront - 1));
376     stw_le_p(did + 26, 0xffff & (timings->ysync - 1));
377 
378     edid_checksum(did + 1, did[2] + 4);
379 }
380 
381 void qemu_edid_generate(uint8_t *edid, size_t size,
382                         qemu_edid_info *info)
383 {
384     Timings timings;
385     uint8_t *desc = edid + 54;
386     uint8_t *xtra3 = NULL;
387     uint8_t *dta = NULL;
388     uint8_t *did = NULL;
389     uint32_t width_mm, height_mm;
390     uint32_t refresh_rate = info->refresh_rate ? info->refresh_rate : 75000;
391     uint32_t dpi = 100; /* if no width_mm/height_mm */
392     uint32_t large_screen = 0;
393 
394     /* =============== set defaults  =============== */
395 
396     if (!info->vendor || strlen(info->vendor) != 3) {
397         info->vendor = "RHT";
398     }
399     if (!info->name) {
400         info->name = "QEMU Monitor";
401     }
402     if (!info->prefx) {
403         info->prefx = 1280;
404     }
405     if (!info->prefy) {
406         info->prefy = 800;
407     }
408     if (info->width_mm && info->height_mm) {
409         width_mm = info->width_mm;
410         height_mm = info->height_mm;
411         dpi = qemu_edid_dpi_from_mm(width_mm, info->prefx);
412     } else {
413         width_mm = qemu_edid_dpi_to_mm(dpi, info->prefx);
414         height_mm = qemu_edid_dpi_to_mm(dpi, info->prefy);
415     }
416 
417     generate_timings(&timings, refresh_rate, info->prefx, info->prefy);
418     if (info->prefx >= 4096 || info->prefy >= 4096 || timings.clock >= 65536) {
419         large_screen = 1;
420     }
421 
422     /* =============== extensions  =============== */
423 
424     if (size >= 256) {
425         dta = edid + 128;
426         edid[126]++;
427         edid_ext_dta(dta);
428     }
429 
430     if (size >= 384 && large_screen) {
431         did = edid + 256;
432         edid[126]++;
433         init_displayid(did);
434     }
435 
436     /* =============== header information =============== */
437 
438     /* fixed */
439     edid[0] = 0x00;
440     edid[1] = 0xff;
441     edid[2] = 0xff;
442     edid[3] = 0xff;
443     edid[4] = 0xff;
444     edid[5] = 0xff;
445     edid[6] = 0xff;
446     edid[7] = 0x00;
447 
448     /* manufacturer id, product code, serial number */
449     uint16_t vendor_id = ((((info->vendor[0] - '@') & 0x1f) << 10) |
450                           (((info->vendor[1] - '@') & 0x1f) <<  5) |
451                           (((info->vendor[2] - '@') & 0x1f) <<  0));
452     uint16_t model_nr = 0x1234;
453     uint32_t serial_nr = info->serial ? atoi(info->serial) : 0;
454     stw_be_p(edid +  8, vendor_id);
455     stw_le_p(edid + 10, model_nr);
456     stl_le_p(edid + 12, serial_nr);
457 
458     /* manufacture week and year */
459     edid[16] = 42;
460     edid[17] = 2014 - 1990;
461 
462     /* edid version */
463     edid[18] = 1;
464     edid[19] = 4;
465 
466 
467     /* =============== basic display parameters =============== */
468 
469     /* video input: digital, 8bpc, displayport */
470     edid[20] = 0xa5;
471 
472     /* screen size: undefined */
473     edid[21] = width_mm / 10;
474     edid[22] = height_mm / 10;
475 
476     /* display gamma: 2.2 */
477     edid[23] = 220 - 100;
478 
479     /* supported features bitmap: std sRGB, preferred timing */
480     edid[24] = 0x06;
481 
482 
483     /* =============== chromaticity coordinates =============== */
484 
485     /* standard sRGB colorspace */
486     edid_colorspace(edid,
487                     0.6400, 0.3300,   /* red   */
488                     0.3000, 0.6000,   /* green */
489                     0.1500, 0.0600,   /* blue  */
490                     0.3127, 0.3290);  /* white point  */
491 
492     /* =============== established timing bitmap =============== */
493     /* =============== standard timing information =============== */
494 
495     /* both filled by edid_fill_modes() */
496 
497 
498     /* =============== descriptor blocks =============== */
499 
500     if (!large_screen) {
501         /* The DTD section has only 12 bits to store the resolution */
502         edid_desc_timing(desc, &timings, info->prefx, info->prefy,
503                          width_mm, height_mm);
504         desc = edid_desc_next(edid, dta, desc);
505     }
506 
507     xtra3 = desc;
508     edid_desc_xtra3_std(xtra3);
509     desc = edid_desc_next(edid, dta, desc);
510     edid_fill_modes(edid, xtra3, dta, info->maxx, info->maxy);
511     /*
512      * dta video data block is finished at thus point,
513      * so dta descriptor offsets don't move any more.
514      */
515 
516     edid_desc_ranges(desc);
517     desc = edid_desc_next(edid, dta, desc);
518 
519     if (desc && info->name) {
520         edid_desc_text(desc, 0xfc, info->name);
521         desc = edid_desc_next(edid, dta, desc);
522     }
523 
524     if (desc && info->serial) {
525         edid_desc_text(desc, 0xff, info->serial);
526         desc = edid_desc_next(edid, dta, desc);
527     }
528 
529     while (desc) {
530         edid_desc_dummy(desc);
531         desc = edid_desc_next(edid, dta, desc);
532     }
533 
534     /* =============== display id extensions =============== */
535 
536     if (did && large_screen) {
537         qemu_displayid_generate(did, &timings, info->prefx, info->prefy,
538                                 width_mm, height_mm);
539     }
540 
541     /* =============== finish up =============== */
542 
543     edid_checksum(edid, 127);
544     if (dta) {
545         edid_checksum(dta, 127);
546     }
547     if (did) {
548         edid_checksum(did, 127);
549     }
550 }
551 
552 size_t qemu_edid_size(uint8_t *edid)
553 {
554     uint32_t exts;
555 
556     if (edid[0] != 0x00 ||
557         edid[1] != 0xff) {
558         /* doesn't look like a valid edid block */
559         return 0;
560     }
561 
562     exts = edid[126];
563     return 128 * (exts + 1);
564 }
565