xref: /openbmc/qemu/hw/display/edid-generate.c (revision 09a274d8)
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-common.h"
9 #include "qemu/bswap.h"
10 #include "hw/display/edid.h"
11 
12 static const struct edid_mode {
13     uint32_t xres;
14     uint32_t yres;
15     uint32_t byte;
16     uint32_t xtra3;
17     uint32_t bit;
18     uint32_t dta;
19 } modes[] = {
20     /* dea/dta extension timings (all @ 50 Hz) */
21     { .xres = 5120,   .yres = 2160,   .dta = 125 },
22     { .xres = 4096,   .yres = 2160,   .dta = 101 },
23     { .xres = 3840,   .yres = 2160,   .dta =  96 },
24     { .xres = 2560,   .yres = 1080,   .dta =  89 },
25     { .xres = 2048,   .yres = 1152 },
26     { .xres = 1920,   .yres = 1080,   .dta =  31 },
27 
28     /* additional standard timings 3 (all @ 60Hz) */
29     { .xres = 1920,   .yres = 1440,   .xtra3 = 11,   .bit = 5 },
30     { .xres = 1920,   .yres = 1200,   .xtra3 = 10,   .bit = 0 },
31     { .xres = 1856,   .yres = 1392,   .xtra3 = 10,   .bit = 3 },
32     { .xres = 1792,   .yres = 1344,   .xtra3 = 10,   .bit = 5 },
33     { .xres = 1600,   .yres = 1200,   .xtra3 =  9,   .bit = 2 },
34     { .xres = 1680,   .yres = 1050,   .xtra3 =  9,   .bit = 5 },
35     { .xres = 1440,   .yres = 1050,   .xtra3 =  8,   .bit = 1 },
36     { .xres = 1440,   .yres =  900,   .xtra3 =  8,   .bit = 5 },
37     { .xres = 1360,   .yres =  768,   .xtra3 =  8,   .bit = 7 },
38     { .xres = 1280,   .yres = 1024,   .xtra3 =  7,   .bit = 1 },
39     { .xres = 1280,   .yres =  960,   .xtra3 =  7,   .bit = 3 },
40     { .xres = 1280,   .yres =  768,   .xtra3 =  7,   .bit = 6 },
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 static void edid_ext_dta(uint8_t *dta)
49 {
50     dta[0] = 0x02;
51     dta[1] = 0x03;
52     dta[2] = 0x05;
53     dta[3] = 0x00;
54 
55     /* video data block */
56     dta[4] = 0x40;
57 }
58 
59 static void edid_ext_dta_mode(uint8_t *dta, uint8_t nr)
60 {
61     dta[dta[2]] = nr;
62     dta[2]++;
63     dta[4]++;
64 }
65 
66 static int edid_std_mode(uint8_t *mode, uint32_t xres, uint32_t yres)
67 {
68     uint32_t aspect;
69 
70     if (xres == 0 || yres == 0) {
71         mode[0] = 0x01;
72         mode[1] = 0x01;
73         return 0;
74 
75     } else if (xres * 10 == yres * 16) {
76         aspect = 0;
77     } else if (xres * 3 == yres * 4) {
78         aspect = 1;
79     } else if (xres * 4 == yres * 5) {
80         aspect = 2;
81     } else if (xres * 9 == yres * 16) {
82         aspect = 3;
83     } else {
84         return -1;
85     }
86 
87     if ((xres / 8) - 31 > 255) {
88         return -1;
89     }
90 
91     mode[0] = (xres / 8) - 31;
92     mode[1] = ((aspect << 6) | (60 - 60));
93     return 0;
94 }
95 
96 static void edid_fill_modes(uint8_t *edid, uint8_t *xtra3, uint8_t *dta,
97                             uint32_t maxx, uint32_t maxy)
98 {
99     const struct edid_mode *mode;
100     int std = 38;
101     int rc, i;
102 
103     for (i = 0; i < ARRAY_SIZE(modes); i++) {
104         mode = modes + i;
105 
106         if ((maxx && mode->xres > maxx) ||
107             (maxy && mode->yres > maxy)) {
108             continue;
109         }
110 
111         if (mode->byte) {
112             edid[mode->byte] |= (1 << mode->bit);
113         } else if (mode->xtra3 && xtra3) {
114             xtra3[mode->xtra3] |= (1 << mode->bit);
115         } else if (std < 54) {
116             rc = edid_std_mode(edid + std, mode->xres, mode->yres);
117             if (rc == 0) {
118                 std += 2;
119             }
120         }
121 
122         if (dta && mode->dta) {
123             edid_ext_dta_mode(dta, mode->dta);
124         }
125     }
126 
127     while (std < 54) {
128         edid_std_mode(edid + std, 0, 0);
129         std += 2;
130     }
131 }
132 
133 static void edid_checksum(uint8_t *edid)
134 {
135     uint32_t sum = 0;
136     int i;
137 
138     for (i = 0; i < 127; i++) {
139         sum += edid[i];
140     }
141     sum &= 0xff;
142     if (sum) {
143         edid[127] = 0x100 - sum;
144     }
145 }
146 
147 static void edid_desc_type(uint8_t *desc, uint8_t type)
148 {
149     desc[0] = 0;
150     desc[1] = 0;
151     desc[2] = 0;
152     desc[3] = type;
153     desc[4] = 0;
154 }
155 
156 static void edid_desc_text(uint8_t *desc, uint8_t type,
157                            const char *text)
158 {
159     size_t len;
160 
161     edid_desc_type(desc, type);
162     memset(desc + 5, ' ', 13);
163 
164     len = strlen(text);
165     if (len > 12) {
166         len = 12;
167     }
168     memcpy(desc + 5, text, len);
169     desc[5 + len] = '\n';
170 }
171 
172 static void edid_desc_ranges(uint8_t *desc)
173 {
174     edid_desc_type(desc, 0xfd);
175 
176     /* vertical (50 -> 125 Hz) */
177     desc[5] =  50;
178     desc[6] = 125;
179 
180     /* horizontal (30 -> 160 kHz) */
181     desc[7] =  30;
182     desc[8] = 160;
183 
184     /* max dot clock (1200 MHz) */
185     desc[9] = 1200 / 10;
186 
187     /* no extended timing information */
188     desc[10] = 0x01;
189 
190     /* padding */
191     desc[11] = '\n';
192     memset(desc + 12, ' ', 6);
193 }
194 
195 /* additional standard timings 3 */
196 static void edid_desc_xtra3_std(uint8_t *desc)
197 {
198     edid_desc_type(desc, 0xf7);
199     desc[5] = 10;
200 }
201 
202 static void edid_desc_dummy(uint8_t *desc)
203 {
204     edid_desc_type(desc, 0x10);
205 }
206 
207 static void edid_desc_timing(uint8_t *desc,
208                              uint32_t xres, uint32_t yres,
209                              uint32_t dpi)
210 {
211     /* physical display size */
212     uint32_t xmm = xres * dpi / 254;
213     uint32_t ymm = yres * dpi / 254;
214 
215     /* pull some realistic looking timings out of thin air */
216     uint32_t xfront = xres * 25 / 100;
217     uint32_t xsync  = xres *  3 / 100;
218     uint32_t xblank = xres * 35 / 100;
219 
220     uint32_t yfront = yres *  5 / 1000;
221     uint32_t ysync  = yres *  5 / 1000;
222     uint32_t yblank = yres * 35 / 1000;
223 
224     uint32_t clock  = 75 * (xres + xblank) * (yres + yblank);
225 
226     stl_le_p(desc, clock / 10000);
227 
228     desc[2] = xres   & 0xff;
229     desc[3] = xblank & 0xff;
230     desc[4] = (((xres   & 0xf00) >> 4) |
231                ((xblank & 0xf00) >> 8));
232 
233     desc[5] = yres   & 0xff;
234     desc[6] = yblank & 0xff;
235     desc[7] = (((yres   & 0xf00) >> 4) |
236                ((yblank & 0xf00) >> 8));
237 
238     desc[8] = xfront & 0xff;
239     desc[9] = xsync  & 0xff;
240 
241     desc[10] = (((yfront & 0x00f) << 4) |
242                 ((ysync  & 0x00f) << 0));
243     desc[11] = (((xfront & 0x300) >> 2) |
244                 ((xsync  & 0x300) >> 4) |
245                 ((yfront & 0x030) >> 2) |
246                 ((ysync  & 0x030) >> 4));
247 
248     desc[12] = xmm & 0xff;
249     desc[13] = ymm & 0xff;
250     desc[14] = (((xmm & 0xf00) >> 4) |
251                 ((ymm & 0xf00) >> 8));
252 
253     desc[17] = 0x18;
254 }
255 
256 static uint32_t edid_to_10bit(float value)
257 {
258     return (uint32_t)(value * 1024 + 0.5);
259 }
260 
261 static void edid_colorspace(uint8_t *edid,
262                             float rx, float ry,
263                             float gx, float gy,
264                             float bx, float by,
265                             float wx, float wy)
266 {
267     uint32_t red_x   = edid_to_10bit(rx);
268     uint32_t red_y   = edid_to_10bit(ry);
269     uint32_t green_x = edid_to_10bit(gx);
270     uint32_t green_y = edid_to_10bit(gy);
271     uint32_t blue_x  = edid_to_10bit(bx);
272     uint32_t blue_y  = edid_to_10bit(by);
273     uint32_t white_x = edid_to_10bit(wx);
274     uint32_t white_y = edid_to_10bit(wy);
275 
276     edid[25] = (((red_x   & 0x03) << 6) |
277                 ((red_y   & 0x03) << 4) |
278                 ((green_x & 0x03) << 2) |
279                 ((green_y & 0x03) << 0));
280     edid[26] = (((blue_x  & 0x03) << 6) |
281                 ((blue_y  & 0x03) << 4) |
282                 ((white_x & 0x03) << 2) |
283                 ((white_y & 0x03) << 0));
284     edid[27] = red_x   >> 2;
285     edid[28] = red_y   >> 2;
286     edid[29] = green_x >> 2;
287     edid[30] = green_y >> 2;
288     edid[31] = blue_x  >> 2;
289     edid[32] = blue_y  >> 2;
290     edid[33] = white_x >> 2;
291     edid[34] = white_y >> 2;
292 }
293 
294 void qemu_edid_generate(uint8_t *edid, size_t size,
295                         qemu_edid_info *info)
296 {
297     uint32_t desc = 54;
298     uint8_t *xtra3 = NULL;
299     uint8_t *dta = NULL;
300 
301     /* =============== set defaults  =============== */
302 
303     if (!info->vendor || strlen(info->vendor) != 3) {
304         info->vendor = "RHT";
305     }
306     if (!info->name) {
307         info->name = "QEMU Monitor";
308     }
309     if (!info->dpi) {
310         info->dpi = 100;
311     }
312     if (!info->prefx) {
313         info->prefx = 1024;
314     }
315     if (!info->prefy) {
316         info->prefy = 768;
317     }
318 
319     /* =============== extensions  =============== */
320 
321     if (size >= 256) {
322         dta = edid + 128;
323         edid[126]++;
324         edid_ext_dta(dta);
325     }
326 
327     /* =============== header information =============== */
328 
329     /* fixed */
330     edid[0] = 0x00;
331     edid[1] = 0xff;
332     edid[2] = 0xff;
333     edid[3] = 0xff;
334     edid[4] = 0xff;
335     edid[5] = 0xff;
336     edid[6] = 0xff;
337     edid[7] = 0x00;
338 
339     /* manufacturer id, product code, serial number */
340     uint16_t vendor_id = ((((info->vendor[0] - '@') & 0x1f) << 10) |
341                           (((info->vendor[1] - '@') & 0x1f) <<  5) |
342                           (((info->vendor[2] - '@') & 0x1f) <<  0));
343     uint16_t model_nr = 0x1234;
344     uint32_t serial_nr = info->serial ? atoi(info->serial) : 0;
345     stw_be_p(edid +  8, vendor_id);
346     stw_le_p(edid + 10, model_nr);
347     stl_le_p(edid + 12, serial_nr);
348 
349     /* manufacture week and year */
350     edid[16] = 42;
351     edid[17] = 2014 - 1990;
352 
353     /* edid version */
354     edid[18] = 1;
355     edid[19] = 4;
356 
357 
358     /* =============== basic display parameters =============== */
359 
360     /* video input: digital, 8bpc, displayport */
361     edid[20] = 0xa5;
362 
363     /* screen size: undefined */
364     edid[21] = info->prefx * info->dpi / 2540;
365     edid[22] = info->prefy * info->dpi / 2540;
366 
367     /* display gamma: 2.2 */
368     edid[23] = 220 - 100;
369 
370     /* supported features bitmap: std sRGB, preferred timing */
371     edid[24] = 0x06;
372 
373 
374     /* =============== chromaticity coordinates =============== */
375 
376     /* standard sRGB colorspace */
377     edid_colorspace(edid,
378                     0.6400, 0.3300,   /* red   */
379                     0.3000, 0.6000,   /* green */
380                     0.1500, 0.0600,   /* blue  */
381                     0.3127, 0.3290);  /* white point  */
382 
383     /* =============== established timing bitmap =============== */
384     /* =============== standard timing information =============== */
385 
386     /* both filled by edid_fill_modes() */
387 
388 
389     /* =============== descriptor blocks =============== */
390 
391     edid_desc_timing(edid + desc, info->prefx, info->prefy, info->dpi);
392     desc += 18;
393 
394     edid_desc_ranges(edid + desc);
395     desc += 18;
396 
397     if (info->name) {
398         edid_desc_text(edid + desc, 0xfc, info->name);
399         desc += 18;
400     }
401 
402     if (info->serial) {
403         edid_desc_text(edid + desc, 0xff, info->serial);
404         desc += 18;
405     }
406 
407     if (desc < 126) {
408         xtra3 = edid + desc;
409         edid_desc_xtra3_std(xtra3);
410         desc += 18;
411     }
412 
413     while (desc < 126) {
414         edid_desc_dummy(edid + desc);
415         desc += 18;
416     }
417 
418     /* =============== finish up =============== */
419 
420     edid_fill_modes(edid, xtra3, dta, info->maxx, info->maxy);
421     edid_checksum(edid);
422     if (dta) {
423         edid_checksum(dta);
424     }
425 }
426 
427 size_t qemu_edid_size(uint8_t *edid)
428 {
429     uint32_t exts;
430 
431     if (edid[0] != 0x00 ||
432         edid[1] != 0xff) {
433         /* doesn't look like a valid edid block */
434         return 0;
435     }
436 
437     exts = edid[126];
438     return 128 * (exts + 1);
439 }
440