1 /*
2 * linux/drivers/video/fbcvt.c - VESA(TM) Coordinated Video Timings
3 *
4 * Copyright (C) 2005 Antonino Daplas <adaplas@pol.net>
5 *
6 * Based from the VESA(TM) Coordinated Video Timing Generator by
7 * Graham Loveridge April 9, 2003 available at
8 * http://www.elo.utfsm.cl/~elo212/docs/CVTd6r1.xls
9 *
10 * This file is subject to the terms and conditions of the GNU General Public
11 * License. See the file COPYING in the main directory of this archive
12 * for more details.
13 *
14 */
15 #include <linux/fb.h>
16 #include <linux/slab.h>
17
18 #define FB_CVT_CELLSIZE 8
19 #define FB_CVT_GTF_C 40
20 #define FB_CVT_GTF_J 20
21 #define FB_CVT_GTF_K 128
22 #define FB_CVT_GTF_M 600
23 #define FB_CVT_MIN_VSYNC_BP 550
24 #define FB_CVT_MIN_VPORCH 3
25 #define FB_CVT_MIN_BPORCH 6
26
27 #define FB_CVT_RB_MIN_VBLANK 460
28 #define FB_CVT_RB_HBLANK 160
29 #define FB_CVT_RB_V_FPORCH 3
30
31 #define FB_CVT_FLAG_REDUCED_BLANK 1
32 #define FB_CVT_FLAG_MARGINS 2
33 #define FB_CVT_FLAG_INTERLACED 4
34
35 struct fb_cvt_data {
36 u32 xres;
37 u32 yres;
38 u32 refresh;
39 u32 f_refresh;
40 u32 pixclock;
41 u32 hperiod;
42 u32 hblank;
43 u32 hfreq;
44 u32 htotal;
45 u32 vtotal;
46 u32 vsync;
47 u32 hsync;
48 u32 h_front_porch;
49 u32 h_back_porch;
50 u32 v_front_porch;
51 u32 v_back_porch;
52 u32 h_margin;
53 u32 v_margin;
54 u32 interlace;
55 u32 aspect_ratio;
56 u32 active_pixels;
57 u32 flags;
58 u32 status;
59 };
60
61 static const unsigned char fb_cvt_vbi_tab[] = {
62 4, /* 4:3 */
63 5, /* 16:9 */
64 6, /* 16:10 */
65 7, /* 5:4 */
66 7, /* 15:9 */
67 8, /* reserved */
68 9, /* reserved */
69 10 /* custom */
70 };
71
72 /* returns hperiod * 1000 */
fb_cvt_hperiod(struct fb_cvt_data * cvt)73 static u32 fb_cvt_hperiod(struct fb_cvt_data *cvt)
74 {
75 u32 num = 1000000000/cvt->f_refresh;
76 u32 den;
77
78 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
79 num -= FB_CVT_RB_MIN_VBLANK * 1000;
80 den = 2 * (cvt->yres/cvt->interlace + 2 * cvt->v_margin);
81 } else {
82 num -= FB_CVT_MIN_VSYNC_BP * 1000;
83 den = 2 * (cvt->yres/cvt->interlace + cvt->v_margin * 2
84 + FB_CVT_MIN_VPORCH + cvt->interlace/2);
85 }
86
87 return 2 * (num/den);
88 }
89
90 /* returns ideal duty cycle * 1000 */
fb_cvt_ideal_duty_cycle(struct fb_cvt_data * cvt)91 static u32 fb_cvt_ideal_duty_cycle(struct fb_cvt_data *cvt)
92 {
93 u32 c_prime = (FB_CVT_GTF_C - FB_CVT_GTF_J) *
94 (FB_CVT_GTF_K) + 256 * FB_CVT_GTF_J;
95 u32 m_prime = (FB_CVT_GTF_K * FB_CVT_GTF_M);
96 u32 h_period_est = cvt->hperiod;
97
98 return (1000 * c_prime - ((m_prime * h_period_est)/1000))/256;
99 }
100
fb_cvt_hblank(struct fb_cvt_data * cvt)101 static u32 fb_cvt_hblank(struct fb_cvt_data *cvt)
102 {
103 u32 hblank = 0;
104
105 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
106 hblank = FB_CVT_RB_HBLANK;
107 else {
108 u32 ideal_duty_cycle = fb_cvt_ideal_duty_cycle(cvt);
109 u32 active_pixels = cvt->active_pixels;
110
111 if (ideal_duty_cycle < 20000)
112 hblank = (active_pixels * 20000)/
113 (100000 - 20000);
114 else {
115 hblank = (active_pixels * ideal_duty_cycle)/
116 (100000 - ideal_duty_cycle);
117 }
118 }
119
120 hblank &= ~((2 * FB_CVT_CELLSIZE) - 1);
121
122 return hblank;
123 }
124
fb_cvt_hsync(struct fb_cvt_data * cvt)125 static u32 fb_cvt_hsync(struct fb_cvt_data *cvt)
126 {
127 u32 hsync;
128
129 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
130 hsync = 32;
131 else
132 hsync = (FB_CVT_CELLSIZE * cvt->htotal)/100;
133
134 hsync &= ~(FB_CVT_CELLSIZE - 1);
135 return hsync;
136 }
137
fb_cvt_vbi_lines(struct fb_cvt_data * cvt)138 static u32 fb_cvt_vbi_lines(struct fb_cvt_data *cvt)
139 {
140 u32 vbi_lines, min_vbi_lines, act_vbi_lines;
141
142 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
143 vbi_lines = (1000 * FB_CVT_RB_MIN_VBLANK)/cvt->hperiod + 1;
144 min_vbi_lines = FB_CVT_RB_V_FPORCH + cvt->vsync +
145 FB_CVT_MIN_BPORCH;
146
147 } else {
148 vbi_lines = (FB_CVT_MIN_VSYNC_BP * 1000)/cvt->hperiod + 1 +
149 FB_CVT_MIN_VPORCH;
150 min_vbi_lines = cvt->vsync + FB_CVT_MIN_BPORCH +
151 FB_CVT_MIN_VPORCH;
152 }
153
154 if (vbi_lines < min_vbi_lines)
155 act_vbi_lines = min_vbi_lines;
156 else
157 act_vbi_lines = vbi_lines;
158
159 return act_vbi_lines;
160 }
161
fb_cvt_vtotal(struct fb_cvt_data * cvt)162 static u32 fb_cvt_vtotal(struct fb_cvt_data *cvt)
163 {
164 u32 vtotal = cvt->yres/cvt->interlace;
165
166 vtotal += 2 * cvt->v_margin + cvt->interlace/2 + fb_cvt_vbi_lines(cvt);
167 vtotal |= cvt->interlace/2;
168
169 return vtotal;
170 }
171
fb_cvt_pixclock(struct fb_cvt_data * cvt)172 static u32 fb_cvt_pixclock(struct fb_cvt_data *cvt)
173 {
174 u32 pixclock;
175
176 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
177 pixclock = (cvt->f_refresh * cvt->vtotal * cvt->htotal)/1000;
178 else
179 pixclock = (cvt->htotal * 1000000)/cvt->hperiod;
180
181 pixclock /= 250;
182 pixclock *= 250;
183 pixclock *= 1000;
184
185 return pixclock;
186 }
187
fb_cvt_aspect_ratio(struct fb_cvt_data * cvt)188 static u32 fb_cvt_aspect_ratio(struct fb_cvt_data *cvt)
189 {
190 u32 xres = cvt->xres;
191 u32 yres = cvt->yres;
192 u32 aspect = -1;
193
194 if (xres == (yres * 4)/3 && !((yres * 4) % 3))
195 aspect = 0;
196 else if (xres == (yres * 16)/9 && !((yres * 16) % 9))
197 aspect = 1;
198 else if (xres == (yres * 16)/10 && !((yres * 16) % 10))
199 aspect = 2;
200 else if (xres == (yres * 5)/4 && !((yres * 5) % 4))
201 aspect = 3;
202 else if (xres == (yres * 15)/9 && !((yres * 15) % 9))
203 aspect = 4;
204 else {
205 printk(KERN_INFO "fbcvt: Aspect ratio not CVT "
206 "standard\n");
207 aspect = 7;
208 cvt->status = 1;
209 }
210
211 return aspect;
212 }
213
fb_cvt_print_name(struct fb_cvt_data * cvt)214 static void fb_cvt_print_name(struct fb_cvt_data *cvt)
215 {
216 u32 pixcount, pixcount_mod;
217 int size = 256;
218 int off = 0;
219 u8 *buf;
220
221 buf = kzalloc(size, GFP_KERNEL);
222 if (!buf)
223 return;
224
225 pixcount = (cvt->xres * (cvt->yres/cvt->interlace))/1000000;
226 pixcount_mod = (cvt->xres * (cvt->yres/cvt->interlace)) % 1000000;
227 pixcount_mod /= 1000;
228
229 off += scnprintf(buf + off, size - off, "fbcvt: %dx%d@%d: CVT Name - ",
230 cvt->xres, cvt->yres, cvt->refresh);
231
232 if (cvt->status) {
233 off += scnprintf(buf + off, size - off,
234 "Not a CVT standard - %d.%03d Mega Pixel Image\n",
235 pixcount, pixcount_mod);
236 } else {
237 if (pixcount)
238 off += scnprintf(buf + off, size - off, "%d", pixcount);
239
240 off += scnprintf(buf + off, size - off, ".%03dM", pixcount_mod);
241
242 if (cvt->aspect_ratio == 0)
243 off += scnprintf(buf + off, size - off, "3");
244 else if (cvt->aspect_ratio == 3)
245 off += scnprintf(buf + off, size - off, "4");
246 else if (cvt->aspect_ratio == 1 || cvt->aspect_ratio == 4)
247 off += scnprintf(buf + off, size - off, "9");
248 else if (cvt->aspect_ratio == 2)
249 off += scnprintf(buf + off, size - off, "A");
250
251 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
252 off += scnprintf(buf + off, size - off, "-R");
253 }
254
255 printk(KERN_INFO "%s\n", buf);
256 kfree(buf);
257 }
258
fb_cvt_convert_to_mode(struct fb_cvt_data * cvt,struct fb_videomode * mode)259 static void fb_cvt_convert_to_mode(struct fb_cvt_data *cvt,
260 struct fb_videomode *mode)
261 {
262 mode->refresh = cvt->f_refresh;
263 mode->pixclock = KHZ2PICOS(cvt->pixclock/1000);
264 mode->left_margin = cvt->h_back_porch;
265 mode->right_margin = cvt->h_front_porch;
266 mode->hsync_len = cvt->hsync;
267 mode->upper_margin = cvt->v_back_porch;
268 mode->lower_margin = cvt->v_front_porch;
269 mode->vsync_len = cvt->vsync;
270
271 mode->sync &= ~(FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT);
272
273 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
274 mode->sync |= FB_SYNC_HOR_HIGH_ACT;
275 else
276 mode->sync |= FB_SYNC_VERT_HIGH_ACT;
277 }
278
279 /*
280 * fb_find_mode_cvt - calculate mode using VESA(TM) CVT
281 * @mode: pointer to fb_videomode; xres, yres, refresh and vmode must be
282 * pre-filled with the desired values
283 * @margins: add margin to calculation (1.8% of xres and yres)
284 * @rb: compute with reduced blanking (for flatpanels)
285 *
286 * RETURNS:
287 * 0 for success
288 * @mode is filled with computed values. If interlaced, the refresh field
289 * will be filled with the field rate (2x the frame rate)
290 *
291 * DESCRIPTION:
292 * Computes video timings using VESA(TM) Coordinated Video Timings
293 */
fb_find_mode_cvt(struct fb_videomode * mode,int margins,int rb)294 int fb_find_mode_cvt(struct fb_videomode *mode, int margins, int rb)
295 {
296 struct fb_cvt_data cvt;
297
298 memset(&cvt, 0, sizeof(cvt));
299
300 if (margins)
301 cvt.flags |= FB_CVT_FLAG_MARGINS;
302
303 if (rb)
304 cvt.flags |= FB_CVT_FLAG_REDUCED_BLANK;
305
306 if (mode->vmode & FB_VMODE_INTERLACED)
307 cvt.flags |= FB_CVT_FLAG_INTERLACED;
308
309 cvt.xres = mode->xres;
310 cvt.yres = mode->yres;
311 cvt.refresh = mode->refresh;
312 cvt.f_refresh = cvt.refresh;
313 cvt.interlace = 1;
314
315 if (!cvt.xres || !cvt.yres || !cvt.refresh) {
316 printk(KERN_INFO "fbcvt: Invalid input parameters\n");
317 return 1;
318 }
319
320 if (!(cvt.refresh == 50 || cvt.refresh == 60 || cvt.refresh == 70 ||
321 cvt.refresh == 85)) {
322 printk(KERN_INFO "fbcvt: Refresh rate not CVT "
323 "standard\n");
324 cvt.status = 1;
325 }
326
327 cvt.xres &= ~(FB_CVT_CELLSIZE - 1);
328
329 if (cvt.flags & FB_CVT_FLAG_INTERLACED) {
330 cvt.interlace = 2;
331 cvt.f_refresh *= 2;
332 }
333
334 if (cvt.flags & FB_CVT_FLAG_REDUCED_BLANK) {
335 if (cvt.refresh != 60) {
336 printk(KERN_INFO "fbcvt: 60Hz refresh rate "
337 "advised for reduced blanking\n");
338 cvt.status = 1;
339 }
340 }
341
342 if (cvt.flags & FB_CVT_FLAG_MARGINS) {
343 cvt.h_margin = (cvt.xres * 18)/1000;
344 cvt.h_margin &= ~(FB_CVT_CELLSIZE - 1);
345 cvt.v_margin = ((cvt.yres/cvt.interlace)* 18)/1000;
346 }
347
348 cvt.aspect_ratio = fb_cvt_aspect_ratio(&cvt);
349 cvt.active_pixels = cvt.xres + 2 * cvt.h_margin;
350 cvt.hperiod = fb_cvt_hperiod(&cvt);
351 cvt.vsync = fb_cvt_vbi_tab[cvt.aspect_ratio];
352 cvt.vtotal = fb_cvt_vtotal(&cvt);
353 cvt.hblank = fb_cvt_hblank(&cvt);
354 cvt.htotal = cvt.active_pixels + cvt.hblank;
355 cvt.hsync = fb_cvt_hsync(&cvt);
356 cvt.pixclock = fb_cvt_pixclock(&cvt);
357 cvt.hfreq = cvt.pixclock/cvt.htotal;
358 cvt.h_back_porch = cvt.hblank/2 + cvt.h_margin;
359 cvt.h_front_porch = cvt.hblank - cvt.hsync - cvt.h_back_porch +
360 2 * cvt.h_margin;
361 cvt.v_front_porch = 3 + cvt.v_margin;
362 cvt.v_back_porch = cvt.vtotal - cvt.yres/cvt.interlace -
363 cvt.v_front_porch - cvt.vsync;
364 fb_cvt_print_name(&cvt);
365 fb_cvt_convert_to_mode(&cvt, mode);
366
367 return 0;
368 }
369