xref: /openbmc/qemu/hw/display/edid-generate.c (revision 89260905)
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 = 1440,   .xtra3 = 11,   .bit = 5 },
29     { .xres = 1920,   .yres = 1200,   .xtra3 = 10,   .bit = 0 },
30     { .xres = 1856,   .yres = 1392,   .xtra3 = 10,   .bit = 3 },
31     { .xres = 1792,   .yres = 1344,   .xtra3 = 10,   .bit = 5 },
32     { .xres = 1600,   .yres = 1200,   .xtra3 =  9,   .bit = 2 },
33     { .xres = 1680,   .yres = 1050,   .xtra3 =  9,   .bit = 5 },
34     { .xres = 1440,   .yres = 1050,   .xtra3 =  8,   .bit = 1 },
35     { .xres = 1440,   .yres =  900,   .xtra3 =  8,   .bit = 5 },
36     { .xres = 1360,   .yres =  768,   .xtra3 =  8,   .bit = 7 },
37     { .xres = 1280,   .yres = 1024,   .xtra3 =  7,   .bit = 1 },
38     { .xres = 1280,   .yres =  960,   .xtra3 =  7,   .bit = 3 },
39     { .xres = 1280,   .yres =  768,   .xtra3 =  7,   .bit = 6 },
40 
41     /* established timings (all @ 60Hz) */
42     { .xres = 1024,   .yres =  768,   .byte  = 36,   .bit = 3 },
43     { .xres =  800,   .yres =  600,   .byte  = 35,   .bit = 0 },
44     { .xres =  640,   .yres =  480,   .byte  = 35,   .bit = 5 },
45 };
46 
47 static void edid_ext_dta(uint8_t *dta)
48 {
49     dta[0] = 0x02;
50     dta[1] = 0x03;
51     dta[2] = 0x05;
52     dta[3] = 0x00;
53 
54     /* video data block */
55     dta[4] = 0x40;
56 }
57 
58 static void edid_ext_dta_mode(uint8_t *dta, uint8_t nr)
59 {
60     dta[dta[2]] = nr;
61     dta[2]++;
62     dta[4]++;
63 }
64 
65 static int edid_std_mode(uint8_t *mode, uint32_t xres, uint32_t yres)
66 {
67     uint32_t aspect;
68 
69     if (xres == 0 || yres == 0) {
70         mode[0] = 0x01;
71         mode[1] = 0x01;
72         return 0;
73 
74     } else if (xres * 10 == yres * 16) {
75         aspect = 0;
76     } else if (xres * 3 == yres * 4) {
77         aspect = 1;
78     } else if (xres * 4 == yres * 5) {
79         aspect = 2;
80     } else if (xres * 9 == yres * 16) {
81         aspect = 3;
82     } else {
83         return -1;
84     }
85 
86     if ((xres / 8) - 31 > 255) {
87         return -1;
88     }
89 
90     mode[0] = (xres / 8) - 31;
91     mode[1] = ((aspect << 6) | (60 - 60));
92     return 0;
93 }
94 
95 static void edid_fill_modes(uint8_t *edid, uint8_t *xtra3, uint8_t *dta,
96                             uint32_t maxx, uint32_t maxy)
97 {
98     const struct edid_mode *mode;
99     int std = 38;
100     int rc, i;
101 
102     for (i = 0; i < ARRAY_SIZE(modes); i++) {
103         mode = modes + i;
104 
105         if ((maxx && mode->xres > maxx) ||
106             (maxy && mode->yres > maxy)) {
107             continue;
108         }
109 
110         if (mode->byte) {
111             edid[mode->byte] |= (1 << mode->bit);
112         } else if (mode->xtra3 && xtra3) {
113             xtra3[mode->xtra3] |= (1 << mode->bit);
114         } else if (std < 54) {
115             rc = edid_std_mode(edid + std, mode->xres, mode->yres);
116             if (rc == 0) {
117                 std += 2;
118             }
119         }
120 
121         if (dta && mode->dta) {
122             edid_ext_dta_mode(dta, mode->dta);
123         }
124     }
125 
126     while (std < 54) {
127         edid_std_mode(edid + std, 0, 0);
128         std += 2;
129     }
130 }
131 
132 static void edid_checksum(uint8_t *edid)
133 {
134     uint32_t sum = 0;
135     int i;
136 
137     for (i = 0; i < 127; i++) {
138         sum += edid[i];
139     }
140     sum &= 0xff;
141     if (sum) {
142         edid[127] = 0x100 - sum;
143     }
144 }
145 
146 static void edid_desc_type(uint8_t *desc, uint8_t type)
147 {
148     desc[0] = 0;
149     desc[1] = 0;
150     desc[2] = 0;
151     desc[3] = type;
152     desc[4] = 0;
153 }
154 
155 static void edid_desc_text(uint8_t *desc, uint8_t type,
156                            const char *text)
157 {
158     size_t len;
159 
160     edid_desc_type(desc, type);
161     memset(desc + 5, ' ', 13);
162 
163     len = strlen(text);
164     if (len > 12) {
165         len = 12;
166     }
167     memcpy(desc + 5, text, len);
168     desc[5 + len] = '\n';
169 }
170 
171 static void edid_desc_ranges(uint8_t *desc)
172 {
173     edid_desc_type(desc, 0xfd);
174 
175     /* vertical (50 -> 125 Hz) */
176     desc[5] =  50;
177     desc[6] = 125;
178 
179     /* horizontal (30 -> 160 kHz) */
180     desc[7] =  30;
181     desc[8] = 160;
182 
183     /* max dot clock (1200 MHz) */
184     desc[9] = 1200 / 10;
185 
186     /* no extended timing information */
187     desc[10] = 0x01;
188 
189     /* padding */
190     desc[11] = '\n';
191     memset(desc + 12, ' ', 6);
192 }
193 
194 /* additional standard timings 3 */
195 static void edid_desc_xtra3_std(uint8_t *desc)
196 {
197     edid_desc_type(desc, 0xf7);
198     desc[5] = 10;
199 }
200 
201 static void edid_desc_dummy(uint8_t *desc)
202 {
203     edid_desc_type(desc, 0x10);
204 }
205 
206 static void edid_desc_timing(uint8_t *desc,
207                              uint32_t xres, uint32_t yres,
208                              uint32_t dpi)
209 {
210     /* physical display size */
211     uint32_t xmm = xres * dpi / 254;
212     uint32_t ymm = yres * dpi / 254;
213 
214     /* pull some realistic looking timings out of thin air */
215     uint32_t xfront = xres * 25 / 100;
216     uint32_t xsync  = xres *  3 / 100;
217     uint32_t xblank = xres * 35 / 100;
218 
219     uint32_t yfront = yres *  5 / 1000;
220     uint32_t ysync  = yres *  5 / 1000;
221     uint32_t yblank = yres * 35 / 1000;
222 
223     uint32_t clock  = 75 * (xres + xblank) * (yres + yblank);
224 
225     stl_le_p(desc, clock / 10000);
226 
227     desc[2] = xres   & 0xff;
228     desc[3] = xblank & 0xff;
229     desc[4] = (((xres   & 0xf00) >> 4) |
230                ((xblank & 0xf00) >> 8));
231 
232     desc[5] = yres   & 0xff;
233     desc[6] = yblank & 0xff;
234     desc[7] = (((yres   & 0xf00) >> 4) |
235                ((yblank & 0xf00) >> 8));
236 
237     desc[8] = xfront & 0xff;
238     desc[9] = xsync  & 0xff;
239 
240     desc[10] = (((yfront & 0x00f) << 4) |
241                 ((ysync  & 0x00f) << 0));
242     desc[11] = (((xfront & 0x300) >> 2) |
243                 ((xsync  & 0x300) >> 4) |
244                 ((yfront & 0x030) >> 2) |
245                 ((ysync  & 0x030) >> 4));
246 
247     desc[12] = xmm & 0xff;
248     desc[13] = ymm & 0xff;
249     desc[14] = (((xmm & 0xf00) >> 4) |
250                 ((ymm & 0xf00) >> 8));
251 
252     desc[17] = 0x18;
253 }
254 
255 static uint32_t edid_to_10bit(float value)
256 {
257     return (uint32_t)(value * 1024 + 0.5);
258 }
259 
260 static void edid_colorspace(uint8_t *edid,
261                             float rx, float ry,
262                             float gx, float gy,
263                             float bx, float by,
264                             float wx, float wy)
265 {
266     uint32_t red_x   = edid_to_10bit(rx);
267     uint32_t red_y   = edid_to_10bit(ry);
268     uint32_t green_x = edid_to_10bit(gx);
269     uint32_t green_y = edid_to_10bit(gy);
270     uint32_t blue_x  = edid_to_10bit(bx);
271     uint32_t blue_y  = edid_to_10bit(by);
272     uint32_t white_x = edid_to_10bit(wx);
273     uint32_t white_y = edid_to_10bit(wy);
274 
275     edid[25] = (((red_x   & 0x03) << 6) |
276                 ((red_y   & 0x03) << 4) |
277                 ((green_x & 0x03) << 2) |
278                 ((green_y & 0x03) << 0));
279     edid[26] = (((blue_x  & 0x03) << 6) |
280                 ((blue_y  & 0x03) << 4) |
281                 ((white_x & 0x03) << 2) |
282                 ((white_y & 0x03) << 0));
283     edid[27] = red_x   >> 2;
284     edid[28] = red_y   >> 2;
285     edid[29] = green_x >> 2;
286     edid[30] = green_y >> 2;
287     edid[31] = blue_x  >> 2;
288     edid[32] = blue_y  >> 2;
289     edid[33] = white_x >> 2;
290     edid[34] = white_y >> 2;
291 }
292 
293 void qemu_edid_generate(uint8_t *edid, size_t size,
294                         qemu_edid_info *info)
295 {
296     uint32_t desc = 54;
297     uint8_t *xtra3 = NULL;
298     uint8_t *dta = NULL;
299 
300     /* =============== set defaults  =============== */
301 
302     if (!info->vendor || strlen(info->vendor) != 3) {
303         info->vendor = "RHT";
304     }
305     if (!info->name) {
306         info->name = "QEMU Monitor";
307     }
308     if (!info->dpi) {
309         info->dpi = 100;
310     }
311     if (!info->prefx) {
312         info->prefx = 1024;
313     }
314     if (!info->prefy) {
315         info->prefy = 768;
316     }
317 
318     /* =============== extensions  =============== */
319 
320     if (size >= 256) {
321         dta = edid + 128;
322         edid[126]++;
323         edid_ext_dta(dta);
324     }
325 
326     /* =============== header information =============== */
327 
328     /* fixed */
329     edid[0] = 0x00;
330     edid[1] = 0xff;
331     edid[2] = 0xff;
332     edid[3] = 0xff;
333     edid[4] = 0xff;
334     edid[5] = 0xff;
335     edid[6] = 0xff;
336     edid[7] = 0x00;
337 
338     /* manufacturer id, product code, serial number */
339     uint16_t vendor_id = ((((info->vendor[0] - '@') & 0x1f) << 10) |
340                           (((info->vendor[1] - '@') & 0x1f) <<  5) |
341                           (((info->vendor[2] - '@') & 0x1f) <<  0));
342     uint16_t model_nr = 0x1234;
343     uint32_t serial_nr = info->serial ? atoi(info->serial) : 0;
344     stw_be_p(edid +  8, vendor_id);
345     stw_le_p(edid + 10, model_nr);
346     stl_le_p(edid + 12, serial_nr);
347 
348     /* manufacture week and year */
349     edid[16] = 42;
350     edid[17] = 2014 - 1990;
351 
352     /* edid version */
353     edid[18] = 1;
354     edid[19] = 4;
355 
356 
357     /* =============== basic display parameters =============== */
358 
359     /* video input: digital, 8bpc, displayport */
360     edid[20] = 0xa5;
361 
362     /* screen size: undefined */
363     edid[21] = info->prefx * info->dpi / 2540;
364     edid[22] = info->prefy * info->dpi / 2540;
365 
366     /* display gamma: 2.2 */
367     edid[23] = 220 - 100;
368 
369     /* supported features bitmap: std sRGB, preferred timing */
370     edid[24] = 0x06;
371 
372 
373     /* =============== chromaticity coordinates =============== */
374 
375     /* standard sRGB colorspace */
376     edid_colorspace(edid,
377                     0.6400, 0.3300,   /* red   */
378                     0.3000, 0.6000,   /* green */
379                     0.1500, 0.0600,   /* blue  */
380                     0.3127, 0.3290);  /* white point  */
381 
382     /* =============== established timing bitmap =============== */
383     /* =============== standard timing information =============== */
384 
385     /* both filled by edid_fill_modes() */
386 
387 
388     /* =============== descriptor blocks =============== */
389 
390     edid_desc_timing(edid + desc, info->prefx, info->prefy, info->dpi);
391     desc += 18;
392 
393     edid_desc_ranges(edid + desc);
394     desc += 18;
395 
396     if (info->name) {
397         edid_desc_text(edid + desc, 0xfc, info->name);
398         desc += 18;
399     }
400 
401     if (info->serial) {
402         edid_desc_text(edid + desc, 0xff, info->serial);
403         desc += 18;
404     }
405 
406     if (desc < 126) {
407         xtra3 = edid + desc;
408         edid_desc_xtra3_std(xtra3);
409         desc += 18;
410     }
411 
412     while (desc < 126) {
413         edid_desc_dummy(edid + desc);
414         desc += 18;
415     }
416 
417     /* =============== finish up =============== */
418 
419     edid_fill_modes(edid, xtra3, dta, info->maxx, info->maxy);
420     edid_checksum(edid);
421     if (dta) {
422         edid_checksum(dta);
423     }
424 }
425 
426 size_t qemu_edid_size(uint8_t *edid)
427 {
428     uint32_t exts;
429 
430     if (edid[0] != 0x00 ||
431         edid[1] != 0xff) {
432         /* doesn't look like a valid edid block */
433         return 0;
434     }
435 
436     exts = edid[126];
437     return 128 * (exts + 1);
438 }
439