xref: /openbmc/qemu/hw/display/edid-generate.c (revision 744c72a8) 
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     /* additional standard timings 3 (all @ 60Hz) */
28     { .xres = 1920,   .yres = 1200,   .xtra3 = 10,   .bit = 0 },
29     { .xres = 1600,   .yres = 1200,   .xtra3 =  9,   .bit = 2 },
30     { .xres = 1680,   .yres = 1050,   .xtra3 =  9,   .bit = 5 },
31     { .xres = 1440,   .yres =  900,   .xtra3 =  8,   .bit = 5 },
32     { .xres = 1280,   .yres = 1024,   .xtra3 =  7,   .bit = 1 },
33     { .xres = 1280,   .yres =  960,   .xtra3 =  7,   .bit = 3 },
34     { .xres = 1280,   .yres =  768,   .xtra3 =  7,   .bit = 6 },
35 
36     { .xres = 1920,   .yres = 1440,   .xtra3 = 11,   .bit = 5 },
37     { .xres = 1856,   .yres = 1392,   .xtra3 = 10,   .bit = 3 },
38     { .xres = 1792,   .yres = 1344,   .xtra3 = 10,   .bit = 5 },
39     { .xres = 1440,   .yres = 1050,   .xtra3 =  8,   .bit = 1 },
40     { .xres = 1360,   .yres =  768,   .xtra3 =  8,   .bit = 7 },
41 
42     /* established timings (all @ 60Hz) */
43     { .xres = 1024,   .yres =  768,   .byte  = 36,   .bit = 3 },
44     { .xres =  800,   .yres =  600,   .byte  = 35,   .bit = 0 },
45     { .xres =  640,   .yres =  480,   .byte  = 35,   .bit = 5 },
46 };
47 
48 typedef struct Timings {
49     uint32_t xfront;
50     uint32_t xsync;
51     uint32_t xblank;
52 
53     uint32_t yfront;
54     uint32_t ysync;
55     uint32_t yblank;
56 
57     uint64_t clock;
58 } Timings;
59 
60 static void generate_timings(Timings *timings, uint32_t refresh_rate,
61                              uint32_t xres, uint32_t yres)
62 {
63     /* pull some realistic looking timings out of thin air */
64     timings->xfront = xres * 25 / 100;
65     timings->xsync  = xres *  3 / 100;
66     timings->xblank = xres * 35 / 100;
67 
68     timings->yfront = yres *  5 / 1000;
69     timings->ysync  = yres *  5 / 1000;
70     timings->yblank = yres * 35 / 1000;
71 
72     timings->clock  = ((uint64_t)refresh_rate *
73                        (xres + timings->xblank) *
74                        (yres + timings->yblank)) / 10000000;
75 }
76 
77 static void edid_ext_dta(uint8_t *dta)
78 {
79     dta[0] = 0x02;
80     dta[1] = 0x03;
81     dta[2] = 0x05;
82     dta[3] = 0x00;
83 
84     /* video data block */
85     dta[4] = 0x40;
86 }
87 
88 static void edid_ext_dta_mode(uint8_t *dta, uint8_t nr)
89 {
90     dta[dta[2]] = nr;
91     dta[2]++;
92     dta[4]++;
93 }
94 
95 static int edid_std_mode(uint8_t *mode, uint32_t xres, uint32_t yres)
96 {
97     uint32_t aspect;
98 
99     if (xres == 0 || yres == 0) {
100         mode[0] = 0x01;
101         mode[1] = 0x01;
102         return 0;
103 
104     } else if (xres * 10 == yres * 16) {
105         aspect = 0;
106     } else if (xres * 3 == yres * 4) {
107         aspect = 1;
108     } else if (xres * 4 == yres * 5) {
109         aspect = 2;
110     } else if (xres * 9 == yres * 16) {
111         aspect = 3;
112     } else {
113         return -1;
114     }
115 
116     if ((xres / 8) - 31 > 255) {
117         return -1;
118     }
119 
120     mode[0] = (xres / 8) - 31;
121     mode[1] = ((aspect << 6) | (60 - 60));
122     return 0;
123 }
124 
125 static void edid_fill_modes(uint8_t *edid, uint8_t *xtra3, uint8_t *dta,
126                             uint32_t maxx, uint32_t maxy)
127 {
128     const struct edid_mode *mode;
129     int std = 38;
130     int rc, i;
131 
132     for (i = 0; i < ARRAY_SIZE(modes); i++) {
133         mode = modes + i;
134 
135         if ((maxx && mode->xres > maxx) ||
136             (maxy && mode->yres > maxy)) {
137             continue;
138         }
139 
140         if (mode->byte) {
141             edid[mode->byte] |= (1 << mode->bit);
142         } else if (std < 54) {
143             rc = edid_std_mode(edid + std, mode->xres, mode->yres);
144             if (rc == 0) {
145                 std += 2;
146             }
147         } else if (mode->xtra3 && xtra3) {
148             xtra3[mode->xtra3] |= (1 << mode->bit);
149         }
150 
151         if (dta && mode->dta) {
152             edid_ext_dta_mode(dta, mode->dta);
153         }
154     }
155 
156     while (std < 54) {
157         edid_std_mode(edid + std, 0, 0);
158         std += 2;
159     }
160 }
161 
162 static void edid_checksum(uint8_t *edid, size_t len)
163 {
164     uint32_t sum = 0;
165     int i;
166 
167     for (i = 0; i < len; i++) {
168         sum += edid[i];
169     }
170     sum &= 0xff;
171     if (sum) {
172         edid[len] = 0x100 - sum;
173     }
174 }
175 
176 static uint8_t *edid_desc_next(uint8_t *edid, uint8_t *dta, uint8_t *desc)
177 {
178     if (desc == NULL) {
179         return NULL;
180     }
181     if (desc + 18 + 18 < edid + 127) {
182         return desc + 18;
183     }
184     if (dta) {
185         if (desc < edid + 127) {
186             return dta + dta[2];
187         }
188         if (desc + 18 + 18 < dta + 127) {
189             return desc + 18;
190         }
191     }
192     return NULL;
193 }
194 
195 static void edid_desc_type(uint8_t *desc, uint8_t type)
196 {
197     desc[0] = 0;
198     desc[1] = 0;
199     desc[2] = 0;
200     desc[3] = type;
201     desc[4] = 0;
202 }
203 
204 static void edid_desc_text(uint8_t *desc, uint8_t type,
205                            const char *text)
206 {
207     size_t len;
208 
209     edid_desc_type(desc, type);
210     memset(desc + 5, ' ', 13);
211 
212     len = strlen(text);
213     if (len > 12) {
214         len = 12;
215     }
216     memcpy(desc + 5, text, len);
217     desc[5 + len] = '\n';
218 }
219 
220 static void edid_desc_ranges(uint8_t *desc)
221 {
222     edid_desc_type(desc, 0xfd);
223 
224     /* vertical (50 -> 125 Hz) */
225     desc[5] =  50;
226     desc[6] = 125;
227 
228     /* horizontal (30 -> 160 kHz) */
229     desc[7] =  30;
230     desc[8] = 160;
231 
232     /* max dot clock (2550 MHz) */
233     desc[9] = 2550 / 10;
234 
235     /* no extended timing information */
236     desc[10] = 0x01;
237 
238     /* padding */
239     desc[11] = '\n';
240     memset(desc + 12, ' ', 6);
241 }
242 
243 /* additional standard timings 3 */
244 static void edid_desc_xtra3_std(uint8_t *desc)
245 {
246     edid_desc_type(desc, 0xf7);
247     desc[5] = 10;
248 }
249 
250 static void edid_desc_dummy(uint8_t *desc)
251 {
252     edid_desc_type(desc, 0x10);
253 }
254 
255 static void edid_desc_timing(uint8_t *desc, uint32_t refresh_rate,
256                              uint32_t xres, uint32_t yres,
257                              uint32_t xmm, uint32_t ymm)
258 {
259     Timings timings;
260     generate_timings(&timings, refresh_rate, xres, yres);
261     stl_le_p(desc, timings.clock);
262 
263     desc[2] = xres   & 0xff;
264     desc[3] = timings.xblank & 0xff;
265     desc[4] = (((xres   & 0xf00) >> 4) |
266                ((timings.xblank & 0xf00) >> 8));
267 
268     desc[5] = yres   & 0xff;
269     desc[6] = timings.yblank & 0xff;
270     desc[7] = (((yres   & 0xf00) >> 4) |
271                ((timings.yblank & 0xf00) >> 8));
272 
273     desc[8] = timings.xfront & 0xff;
274     desc[9] = timings.xsync  & 0xff;
275 
276     desc[10] = (((timings.yfront & 0x00f) << 4) |
277                 ((timings.ysync  & 0x00f) << 0));
278     desc[11] = (((timings.xfront & 0x300) >> 2) |
279                 ((timings.xsync  & 0x300) >> 4) |
280                 ((timings.yfront & 0x030) >> 2) |
281                 ((timings.ysync  & 0x030) >> 4));
282 
283     desc[12] = xmm & 0xff;
284     desc[13] = ymm & 0xff;
285     desc[14] = (((xmm & 0xf00) >> 4) |
286                 ((ymm & 0xf00) >> 8));
287 
288     desc[17] = 0x18;
289 }
290 
291 static uint32_t edid_to_10bit(float value)
292 {
293     return (uint32_t)(value * 1024 + 0.5);
294 }
295 
296 static void edid_colorspace(uint8_t *edid,
297                             float rx, float ry,
298                             float gx, float gy,
299                             float bx, float by,
300                             float wx, float wy)
301 {
302     uint32_t red_x   = edid_to_10bit(rx);
303     uint32_t red_y   = edid_to_10bit(ry);
304     uint32_t green_x = edid_to_10bit(gx);
305     uint32_t green_y = edid_to_10bit(gy);
306     uint32_t blue_x  = edid_to_10bit(bx);
307     uint32_t blue_y  = edid_to_10bit(by);
308     uint32_t white_x = edid_to_10bit(wx);
309     uint32_t white_y = edid_to_10bit(wy);
310 
311     edid[25] = (((red_x   & 0x03) << 6) |
312                 ((red_y   & 0x03) << 4) |
313                 ((green_x & 0x03) << 2) |
314                 ((green_y & 0x03) << 0));
315     edid[26] = (((blue_x  & 0x03) << 6) |
316                 ((blue_y  & 0x03) << 4) |
317                 ((white_x & 0x03) << 2) |
318                 ((white_y & 0x03) << 0));
319     edid[27] = red_x   >> 2;
320     edid[28] = red_y   >> 2;
321     edid[29] = green_x >> 2;
322     edid[30] = green_y >> 2;
323     edid[31] = blue_x  >> 2;
324     edid[32] = blue_y  >> 2;
325     edid[33] = white_x >> 2;
326     edid[34] = white_y >> 2;
327 }
328 
329 static uint32_t qemu_edid_dpi_from_mm(uint32_t mm, uint32_t res)
330 {
331     return res * 254 / 10 / mm;
332 }
333 
334 uint32_t qemu_edid_dpi_to_mm(uint32_t dpi, uint32_t res)
335 {
336     return res * 254 / 10 / dpi;
337 }
338 
339 static void init_displayid(uint8_t *did)
340 {
341     did[0] = 0x70; /* display id extension */
342     did[1] = 0x13; /* version 1.3 */
343     did[2] = 4;    /* length */
344     did[3] = 0x03; /* product type (0x03 == standalone display device) */
345     edid_checksum(did + 1, did[2] + 4);
346 }
347 
348 static void qemu_displayid_generate(uint8_t *did, uint32_t refresh_rate,
349                                     uint32_t xres, uint32_t yres,
350                                     uint32_t xmm, uint32_t ymm)
351 {
352     Timings timings;
353     generate_timings(&timings, refresh_rate, xres, yres);
354 
355     did[0] = 0x70; /* display id extension */
356     did[1] = 0x13; /* version 1.3 */
357     did[2] = 23;   /* length */
358     did[3] = 0x03; /* product type (0x03 == standalone display device) */
359 
360     did[5] = 0x03; /* Detailed Timings Data Block */
361     did[6] = 0x00; /* revision */
362     did[7] = 0x14; /* block length */
363 
364     did[8]  = timings.clock  & 0xff;
365     did[9]  = (timings.clock & 0xff00) >> 8;
366     did[10] = (timings.clock & 0xff0000) >> 16;
367 
368     did[11] = 0x88; /* leave aspect ratio undefined */
369 
370     stw_le_p(did + 12, 0xffff & (xres - 1));
371     stw_le_p(did + 14, 0xffff & (timings.xblank - 1));
372     stw_le_p(did + 16, 0xffff & (timings.xfront - 1));
373     stw_le_p(did + 18, 0xffff & (timings.xsync - 1));
374 
375     stw_le_p(did + 20, 0xffff & (yres - 1));
376     stw_le_p(did + 22, 0xffff & (timings.yblank - 1));
377     stw_le_p(did + 24, 0xffff & (timings.yfront - 1));
378     stw_le_p(did + 26, 0xffff & (timings.ysync - 1));
379 
380     edid_checksum(did + 1, did[2] + 4);
381 }
382 
383 void qemu_edid_generate(uint8_t *edid, size_t size,
384                         qemu_edid_info *info)
385 {
386     uint8_t *desc = edid + 54;
387     uint8_t *xtra3 = NULL;
388     uint8_t *dta = NULL;
389     uint8_t *did = NULL;
390     uint32_t width_mm, height_mm;
391     uint32_t refresh_rate = info->refresh_rate ? info->refresh_rate : 75000;
392     uint32_t dpi = 100; /* if no width_mm/height_mm */
393     uint32_t large_screen = 0;
394 
395     /* =============== set defaults  =============== */
396 
397     if (!info->vendor || strlen(info->vendor) != 3) {
398         info->vendor = "RHT";
399     }
400     if (!info->name) {
401         info->name = "QEMU Monitor";
402     }
403     if (!info->prefx) {
404         info->prefx = 1024;
405     }
406     if (!info->prefy) {
407         info->prefy = 768;
408     }
409     if (info->prefx >= 4096 || info->prefy >= 4096) {
410         large_screen = 1;
411     }
412     if (info->width_mm && info->height_mm) {
413         width_mm = info->width_mm;
414         height_mm = info->height_mm;
415         dpi = qemu_edid_dpi_from_mm(width_mm, info->prefx);
416     } else {
417         width_mm = qemu_edid_dpi_to_mm(dpi, info->prefx);
418         height_mm = qemu_edid_dpi_to_mm(dpi, info->prefy);
419     }
420 
421     /* =============== extensions  =============== */
422 
423     if (size >= 256) {
424         dta = edid + 128;
425         edid[126]++;
426         edid_ext_dta(dta);
427     }
428 
429     if (size >= 384 && large_screen) {
430         did = edid + 256;
431         edid[126]++;
432         init_displayid(did);
433     }
434 
435     /* =============== header information =============== */
436 
437     /* fixed */
438     edid[0] = 0x00;
439     edid[1] = 0xff;
440     edid[2] = 0xff;
441     edid[3] = 0xff;
442     edid[4] = 0xff;
443     edid[5] = 0xff;
444     edid[6] = 0xff;
445     edid[7] = 0x00;
446 
447     /* manufacturer id, product code, serial number */
448     uint16_t vendor_id = ((((info->vendor[0] - '@') & 0x1f) << 10) |
449                           (((info->vendor[1] - '@') & 0x1f) <<  5) |
450                           (((info->vendor[2] - '@') & 0x1f) <<  0));
451     uint16_t model_nr = 0x1234;
452     uint32_t serial_nr = info->serial ? atoi(info->serial) : 0;
453     stw_be_p(edid +  8, vendor_id);
454     stw_le_p(edid + 10, model_nr);
455     stl_le_p(edid + 12, serial_nr);
456 
457     /* manufacture week and year */
458     edid[16] = 42;
459     edid[17] = 2014 - 1990;
460 
461     /* edid version */
462     edid[18] = 1;
463     edid[19] = 4;
464 
465 
466     /* =============== basic display parameters =============== */
467 
468     /* video input: digital, 8bpc, displayport */
469     edid[20] = 0xa5;
470 
471     /* screen size: undefined */
472     edid[21] = width_mm / 10;
473     edid[22] = height_mm / 10;
474 
475     /* display gamma: 2.2 */
476     edid[23] = 220 - 100;
477 
478     /* supported features bitmap: std sRGB, preferred timing */
479     edid[24] = 0x06;
480 
481 
482     /* =============== chromaticity coordinates =============== */
483 
484     /* standard sRGB colorspace */
485     edid_colorspace(edid,
486                     0.6400, 0.3300,   /* red   */
487                     0.3000, 0.6000,   /* green */
488                     0.1500, 0.0600,   /* blue  */
489                     0.3127, 0.3290);  /* white point  */
490 
491     /* =============== established timing bitmap =============== */
492     /* =============== standard timing information =============== */
493 
494     /* both filled by edid_fill_modes() */
495 
496 
497     /* =============== descriptor blocks =============== */
498 
499     if (!large_screen) {
500         /* The DTD section has only 12 bits to store the resolution */
501         edid_desc_timing(desc, refresh_rate, info->prefx, info->prefy,
502                          width_mm, height_mm);
503         desc = edid_desc_next(edid, dta, desc);
504     }
505 
506     xtra3 = desc;
507     edid_desc_xtra3_std(xtra3);
508     desc = edid_desc_next(edid, dta, desc);
509     edid_fill_modes(edid, xtra3, dta, info->maxx, info->maxy);
510     /*
511      * dta video data block is finished at thus point,
512      * so dta descriptor offsets don't move any more.
513      */
514 
515     edid_desc_ranges(desc);
516     desc = edid_desc_next(edid, dta, desc);
517 
518     if (desc && info->name) {
519         edid_desc_text(desc, 0xfc, info->name);
520         desc = edid_desc_next(edid, dta, desc);
521     }
522 
523     if (desc && info->serial) {
524         edid_desc_text(desc, 0xff, info->serial);
525         desc = edid_desc_next(edid, dta, desc);
526     }
527 
528     while (desc) {
529         edid_desc_dummy(desc);
530         desc = edid_desc_next(edid, dta, desc);
531     }
532 
533     /* =============== display id extensions =============== */
534 
535     if (did && large_screen) {
536         qemu_displayid_generate(did, refresh_rate, info->prefx, info->prefy,
537                                 width_mm, height_mm);
538     }
539 
540     /* =============== finish up =============== */
541 
542     edid_checksum(edid, 127);
543     if (dta) {
544         edid_checksum(dta, 127);
545     }
546     if (did) {
547         edid_checksum(did, 127);
548     }
549 }
550 
551 size_t qemu_edid_size(uint8_t *edid)
552 {
553     uint32_t exts;
554 
555     if (edid[0] != 0x00 ||
556         edid[1] != 0xff) {
557         /* doesn't look like a valid edid block */
558         return 0;
559     }
560 
561     exts = edid[126];
562     return 128 * (exts + 1);
563 }
564