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 */ 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 */ 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 } 100 101 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 } 124 125 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 } 137 138 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 } 161 162 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 } 171 172 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 } 187 188 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 } 213 214 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 } 258 259 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 */ 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