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 34struct 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 60static 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 */ 72static 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 */ 90static 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 100static 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 124static 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 137static 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 161static 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 171static 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 187static 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 213static 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 269static 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 */ 304int 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} 379