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Committer: Michael Beasley <mike@snafu.setup>
[mikesnafu-overlay.git] / drivers / video / fbcvt.c
blob0847c5e72cbd73ff2fcf53afe59c1d729810e2d9
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.vesa.org/public/CVT/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
17 #define FB_CVT_CELLSIZE 8
18 #define FB_CVT_GTF_C 40
19 #define FB_CVT_GTF_J 20
20 #define FB_CVT_GTF_K 128
21 #define FB_CVT_GTF_M 600
22 #define FB_CVT_MIN_VSYNC_BP 550
23 #define FB_CVT_MIN_VPORCH 3
24 #define FB_CVT_MIN_BPORCH 6
25
26 #define FB_CVT_RB_MIN_VBLANK 460
27 #define FB_CVT_RB_HBLANK 160
28 #define FB_CVT_RB_V_FPORCH 3
29
30 #define FB_CVT_FLAG_REDUCED_BLANK 1
31 #define FB_CVT_FLAG_MARGINS 2
32 #define FB_CVT_FLAG_INTERLACED 4
33
34 struct fb_cvt_data {
35 u32 xres;
36 u32 yres;
37 u32 refresh;
38 u32 f_refresh;
39 u32 pixclock;
40 u32 hperiod;
41 u32 hblank;
42 u32 hfreq;
43 u32 htotal;
44 u32 vtotal;
45 u32 vsync;
46 u32 hsync;
47 u32 h_front_porch;
48 u32 h_back_porch;
49 u32 v_front_porch;
50 u32 v_back_porch;
51 u32 h_margin;
52 u32 v_margin;
53 u32 interlace;
54 u32 aspect_ratio;
55 u32 active_pixels;
56 u32 flags;
57 u32 status;
58 };
59
60 static const unsigned char fb_cvt_vbi_tab[] = {
61 4, /* 4:3 */
62 5, /* 16:9 */
63 6, /* 16:10 */
64 7, /* 5:4 */
65 7, /* 15:9 */
66 8, /* reserved */
67 9, /* reserved */
68 10 /* custom */
69 };
70
71 /* returns hperiod * 1000 */
72 static u32 fb_cvt_hperiod(struct fb_cvt_data *cvt)
73 {
74 u32 num = 1000000000/cvt->f_refresh;
75 u32 den;
76
77 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
78 num -= FB_CVT_RB_MIN_VBLANK * 1000;
79 den = 2 * (cvt->yres/cvt->interlace + 2 * cvt->v_margin);
80 } else {
81 num -= FB_CVT_MIN_VSYNC_BP * 1000;
82 den = 2 * (cvt->yres/cvt->interlace + cvt->v_margin * 2
83 + FB_CVT_MIN_VPORCH + cvt->interlace/2);
84 }
85
86 return 2 * (num/den);
87 }
88
89 /* returns ideal duty cycle * 1000 */
90 static u32 fb_cvt_ideal_duty_cycle(struct fb_cvt_data *cvt)
91 {
92 u32 c_prime = (FB_CVT_GTF_C - FB_CVT_GTF_J) *
93 (FB_CVT_GTF_K) + 256 * FB_CVT_GTF_J;
94 u32 m_prime = (FB_CVT_GTF_K * FB_CVT_GTF_M);
95 u32 h_period_est = cvt->hperiod;
96
97 return (1000 * c_prime - ((m_prime * h_period_est)/1000))/256;
98 }
99
100 static u32 fb_cvt_hblank(struct fb_cvt_data *cvt)
101 {
102 u32 hblank = 0;
103
104 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
105 hblank = FB_CVT_RB_HBLANK;
106 else {
107 u32 ideal_duty_cycle = fb_cvt_ideal_duty_cycle(cvt);
108 u32 active_pixels = cvt->active_pixels;
109
110 if (ideal_duty_cycle < 20000)
111 hblank = (active_pixels * 20000)/
112 (100000 - 20000);
113 else {
114 hblank = (active_pixels * ideal_duty_cycle)/
115 (100000 - ideal_duty_cycle);
116 }
117 }
118
119 hblank &= ~((2 * FB_CVT_CELLSIZE) - 1);
120
121 return hblank;
122 }
123
124 static u32 fb_cvt_hsync(struct fb_cvt_data *cvt)
125 {
126 u32 hsync;
127
128 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
129 hsync = 32;
130 else
131 hsync = (FB_CVT_CELLSIZE * cvt->htotal)/100;
132
133 hsync &= ~(FB_CVT_CELLSIZE - 1);
134 return hsync;
135 }
136
137 static u32 fb_cvt_vbi_lines(struct fb_cvt_data *cvt)
138 {
139 u32 vbi_lines, min_vbi_lines, act_vbi_lines;
140
141 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
142 vbi_lines = (1000 * FB_CVT_RB_MIN_VBLANK)/cvt->hperiod + 1;
143 min_vbi_lines = FB_CVT_RB_V_FPORCH + cvt->vsync +
144 FB_CVT_MIN_BPORCH;
145
146 } else {
147 vbi_lines = (FB_CVT_MIN_VSYNC_BP * 1000)/cvt->hperiod + 1 +
148 FB_CVT_MIN_VPORCH;
149 min_vbi_lines = cvt->vsync + FB_CVT_MIN_BPORCH +
150 FB_CVT_MIN_VPORCH;
151 }
152
153 if (vbi_lines < min_vbi_lines)
154 act_vbi_lines = min_vbi_lines;
155 else
156 act_vbi_lines = vbi_lines;
157
158 return act_vbi_lines;
159 }
160
161 static u32 fb_cvt_vtotal(struct fb_cvt_data *cvt)
162 {
163 u32 vtotal = cvt->yres/cvt->interlace;
164
165 vtotal += 2 * cvt->v_margin + cvt->interlace/2 + fb_cvt_vbi_lines(cvt);
166 vtotal |= cvt->interlace/2;
167
168 return vtotal;
169 }
170
171 static u32 fb_cvt_pixclock(struct fb_cvt_data *cvt)
172 {
173 u32 pixclock;
174
175 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
176 pixclock = (cvt->f_refresh * cvt->vtotal * cvt->htotal)/1000;
177 else
178 pixclock = (cvt->htotal * 1000000)/cvt->hperiod;
179
180 pixclock /= 250;
181 pixclock *= 250;
182 pixclock *= 1000;
183
184 return pixclock;
185 }
186
187 static u32 fb_cvt_aspect_ratio(struct fb_cvt_data *cvt)
188 {
189 u32 xres = cvt->xres;
190 u32 yres = cvt->yres;
191 u32 aspect = -1;
192
193 if (xres == (yres * 4)/3 && !((yres * 4) % 3))
194 aspect = 0;
195 else if (xres == (yres * 16)/9 && !((yres * 16) % 9))
196 aspect = 1;
197 else if (xres == (yres * 16)/10 && !((yres * 16) % 10))
198 aspect = 2;
199 else if (xres == (yres * 5)/4 && !((yres * 5) % 4))
200 aspect = 3;
201 else if (xres == (yres * 15)/9 && !((yres * 15) % 9))
202 aspect = 4;
203 else {
204 printk(KERN_INFO "fbcvt: Aspect ratio not CVT "
205 "standard\n");
206 aspect = 7;
207 cvt->status = 1;
208 }
209
210 return aspect;
211 }
212
213 static void fb_cvt_print_name(struct fb_cvt_data *cvt)
214 {
215 u32 pixcount, pixcount_mod;
216 int cnt = 255, offset = 0, read = 0;
217 u8 *buf = kzalloc(256, GFP_KERNEL);
218
219 if (!buf)
220 return;
221
222 pixcount = (cvt->xres * (cvt->yres/cvt->interlace))/1000000;
223 pixcount_mod = (cvt->xres * (cvt->yres/cvt->interlace)) % 1000000;
224 pixcount_mod /= 1000;
225
226 read = snprintf(buf+offset, cnt, "fbcvt: %dx%d@%d: CVT Name - ",
227 cvt->xres, cvt->yres, cvt->refresh);
228 offset += read;
229 cnt -= read;
230
231 if (cvt->status)
232 snprintf(buf+offset, cnt, "Not a CVT standard - %d.%03d Mega "
233 "Pixel Image\n", pixcount, pixcount_mod);
234 else {
235 if (pixcount) {
236 read = snprintf(buf+offset, cnt, "%d", pixcount);
237 cnt -= read;
238 offset += read;
239 }
240
241 read = snprintf(buf+offset, cnt, ".%03dM", pixcount_mod);
242 cnt -= read;
243 offset += read;
244
245 if (cvt->aspect_ratio == 0)
246 read = snprintf(buf+offset, cnt, "3");
247 else if (cvt->aspect_ratio == 3)
248 read = snprintf(buf+offset, cnt, "4");
249 else if (cvt->aspect_ratio == 1 || cvt->aspect_ratio == 4)
250 read = snprintf(buf+offset, cnt, "9");
251 else if (cvt->aspect_ratio == 2)
252 read = snprintf(buf+offset, cnt, "A");
253 else
254 read = 0;
255 cnt -= read;
256 offset += read;
257
258 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
259 read = snprintf(buf+offset, cnt, "-R");
260 cnt -= read;
261 offset += read;
262 }
263 }
264
265 printk(KERN_INFO "%s\n", buf);
266 kfree(buf);
267 }
268
269 static void fb_cvt_convert_to_mode(struct fb_cvt_data *cvt,
270 struct fb_videomode *mode)
271 {
272 mode->refresh = cvt->f_refresh;
273 mode->pixclock = KHZ2PICOS(cvt->pixclock/1000);
274 mode->left_margin = cvt->h_back_porch;
275 mode->right_margin = cvt->h_front_porch;
276 mode->hsync_len = cvt->hsync;
277 mode->upper_margin = cvt->v_back_porch;
278 mode->lower_margin = cvt->v_front_porch;
279 mode->vsync_len = cvt->vsync;
280
281 mode->sync &= ~(FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT);
282
283 if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
284 mode->sync |= FB_SYNC_HOR_HIGH_ACT;
285 else
286 mode->sync |= FB_SYNC_VERT_HIGH_ACT;
287 }
288
289 /*
290 * fb_find_mode_cvt - calculate mode using VESA(TM) CVT
291 * @mode: pointer to fb_videomode; xres, yres, refresh and vmode must be
292 * pre-filled with the desired values
293 * @margins: add margin to calculation (1.8% of xres and yres)
294 * @rb: compute with reduced blanking (for flatpanels)
295 *
296 * RETURNS:
297 * 0 for success
298 * @mode is filled with computed values. If interlaced, the refresh field
299 * will be filled with the field rate (2x the frame rate)
300 *
301 * DESCRIPTION:
302 * Computes video timings using VESA(TM) Coordinated Video Timings
303 */
304 int fb_find_mode_cvt(struct fb_videomode *mode, int margins, int rb)
305 {
306 struct fb_cvt_data cvt;
307
308 memset(&cvt, 0, sizeof(cvt));
309
310 if (margins)
311 cvt.flags |= FB_CVT_FLAG_MARGINS;
312
313 if (rb)
314 cvt.flags |= FB_CVT_FLAG_REDUCED_BLANK;
315
316 if (mode->vmode & FB_VMODE_INTERLACED)
317 cvt.flags |= FB_CVT_FLAG_INTERLACED;
318
319 cvt.xres = mode->xres;
320 cvt.yres = mode->yres;
321 cvt.refresh = mode->refresh;
322 cvt.f_refresh = cvt.refresh;
323 cvt.interlace = 1;
324
325 if (!cvt.xres || !cvt.yres || !cvt.refresh) {
326 printk(KERN_INFO "fbcvt: Invalid input parameters\n");
327 return 1;
328 }
329
330 if (!(cvt.refresh == 50 || cvt.refresh == 60 || cvt.refresh == 70 ||
331 cvt.refresh == 85)) {
332 printk(KERN_INFO "fbcvt: Refresh rate not CVT "
333 "standard\n");
334 cvt.status = 1;
335 }
336
337 cvt.xres &= ~(FB_CVT_CELLSIZE - 1);
338
339 if (cvt.flags & FB_CVT_FLAG_INTERLACED) {
340 cvt.interlace = 2;
341 cvt.f_refresh *= 2;
342 }
343
344 if (cvt.flags & FB_CVT_FLAG_REDUCED_BLANK) {
345 if (cvt.refresh != 60) {
346 printk(KERN_INFO "fbcvt: 60Hz refresh rate "
347 "advised for reduced blanking\n");
348 cvt.status = 1;
349 }
350 }
351
352 if (cvt.flags & FB_CVT_FLAG_MARGINS) {
353 cvt.h_margin = (cvt.xres * 18)/1000;
354 cvt.h_margin &= ~(FB_CVT_CELLSIZE - 1);
355 cvt.v_margin = ((cvt.yres/cvt.interlace)* 18)/1000;
356 }
357
358 cvt.aspect_ratio = fb_cvt_aspect_ratio(&cvt);
359 cvt.active_pixels = cvt.xres + 2 * cvt.h_margin;
360 cvt.hperiod = fb_cvt_hperiod(&cvt);
361 cvt.vsync = fb_cvt_vbi_tab[cvt.aspect_ratio];
362 cvt.vtotal = fb_cvt_vtotal(&cvt);
363 cvt.hblank = fb_cvt_hblank(&cvt);
364 cvt.htotal = cvt.active_pixels + cvt.hblank;
365 cvt.hsync = fb_cvt_hsync(&cvt);
366 cvt.pixclock = fb_cvt_pixclock(&cvt);
367 cvt.hfreq = cvt.pixclock/cvt.htotal;
368 cvt.h_back_porch = cvt.hblank/2 + cvt.h_margin;
369 cvt.h_front_porch = cvt.hblank - cvt.hsync - cvt.h_back_porch +
370 2 * cvt.h_margin;
371 cvt.v_back_porch = 3 + cvt.v_margin;
372 cvt.v_front_porch = cvt.vtotal - cvt.yres/cvt.interlace -
373 cvt.v_back_porch - cvt.vsync;
374 fb_cvt_print_name(&cvt);
375 fb_cvt_convert_to_mode(&cvt, mode);
376
377 return 0;
378 }
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