drivers/media/i2c/smiapp-pll.c

   1 /*
   2  * drivers/media/i2c/smiapp-pll.c
   3  *
   4  * Generic driver for SMIA/SMIA++ compliant camera modules
   5  *
   6  * Copyright (C) 2011--2012 Nokia Corporation
   7  * Contact: Sakari Ailus <sakari.ailus@iki.fi>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License
  11  * version 2 as published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  21  * 02110-1301 USA
  22  *
  23  */
  24
  25 #include <linux/gcd.h>
  26 #include <linux/lcm.h>
  27 #include <linux/module.h>
  28
  29 #include "smiapp-pll.h"
  30
  31 /* Return an even number or one. */
  32 static inline uint32_t clk_div_even(uint32_t a)
  33 {
  34         return max_t(uint32_t, 1, a & ~1);
  35 }
  36
  37 /* Return an even number or one. */
  38 static inline uint32_t clk_div_even_up(uint32_t a)
  39 {
  40         if (a == 1)
  41                 return 1;
  42         return (a + 1) & ~1;
  43 }
  44
  45 static inline uint32_t is_one_or_even(uint32_t a)
  46 {
  47         if (a == 1)
  48                 return 1;
  49         if (a & 1)
  50                 return 0;
  51
  52         return 1;
  53 }
  54
  55 static int bounds_check(struct device *dev, uint32_t val,
  56                         uint32_t min, uint32_t max, char *str)
  57 {
  58         if (val >= min && val <= max)
  59                 return 0;
  60
  61         dev_dbg(dev, "%s out of bounds: %d (%d--%d)\n", str, val, min, max);
  62
  63         return -EINVAL;
  64 }
  65
  66 static void print_pll(struct device *dev, struct smiapp_pll *pll)
  67 {
  68         dev_dbg(dev, "pre_pll_clk_div\t%d\n",  pll->pre_pll_clk_div);
  69         dev_dbg(dev, "pll_multiplier \t%d\n",  pll->pll_multiplier);
  70         if (!(pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)) {
  71                 dev_dbg(dev, "op_sys_clk_div \t%d\n", pll->op_sys_clk_div);
  72                 dev_dbg(dev, "op_pix_clk_div \t%d\n", pll->op_pix_clk_div);
  73         }
  74         dev_dbg(dev, "vt_sys_clk_div \t%d\n",  pll->vt_sys_clk_div);
  75         dev_dbg(dev, "vt_pix_clk_div \t%d\n",  pll->vt_pix_clk_div);
  76
  77         dev_dbg(dev, "ext_clk_freq_hz \t%d\n", pll->ext_clk_freq_hz);
  78         dev_dbg(dev, "pll_ip_clk_freq_hz \t%d\n", pll->pll_ip_clk_freq_hz);
  79         dev_dbg(dev, "pll_op_clk_freq_hz \t%d\n", pll->pll_op_clk_freq_hz);
  80         if (!(pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)) {
  81                 dev_dbg(dev, "op_sys_clk_freq_hz \t%d\n",
  82                         pll->op_sys_clk_freq_hz);
  83                 dev_dbg(dev, "op_pix_clk_freq_hz \t%d\n",
  84                         pll->op_pix_clk_freq_hz);
  85         }
  86         dev_dbg(dev, "vt_sys_clk_freq_hz \t%d\n", pll->vt_sys_clk_freq_hz);
  87         dev_dbg(dev, "vt_pix_clk_freq_hz \t%d\n", pll->vt_pix_clk_freq_hz);
  88 }
  89
  90 /*
  91  * Heuristically guess the PLL tree for a given common multiplier and
  92  * divisor. Begin with the operational timing and continue to video
  93  * timing once operational timing has been verified.
  94  *
  95  * @mul is the PLL multiplier and @div is the common divisor
  96  * (pre_pll_clk_div and op_sys_clk_div combined). The final PLL
  97  * multiplier will be a multiple of @mul.
  98  *
  99  * @return Zero on success, error code on error.
 100  */
 101 static int __smiapp_pll_calculate(struct device *dev,
 102                                   const struct smiapp_pll_limits *limits,
 103                                   struct smiapp_pll *pll, uint32_t mul,
 104                                   uint32_t div, uint32_t lane_op_clock_ratio)
 105 {
 106         uint32_t sys_div;
 107         uint32_t best_pix_div = INT_MAX >> 1;
 108         uint32_t vt_op_binning_div;
 109         /*
 110          * Higher multipliers (and divisors) are often required than
 111          * necessitated by the external clock and the output clocks.
 112          * There are limits for all values in the clock tree. These
 113          * are the minimum and maximum multiplier for mul.
 114          */
 115         uint32_t more_mul_min, more_mul_max;
 116         uint32_t more_mul_factor;
 117         uint32_t min_vt_div, max_vt_div, vt_div;
 118         uint32_t min_sys_div, max_sys_div;
 119         unsigned int i;
 120         int rval;
 121
 122         /*
 123          * Get pre_pll_clk_div so that our pll_op_clk_freq_hz won't be
 124          * too high.
 125          */
 126         dev_dbg(dev, "pre_pll_clk_div %d\n", pll->pre_pll_clk_div);
 127
 128         /* Don't go above max pll multiplier. */
 129         more_mul_max = limits->max_pll_multiplier / mul;
 130         dev_dbg(dev, "more_mul_max: max_pll_multiplier check: %d\n",
 131                 more_mul_max);
 132         /* Don't go above max pll op frequency. */
 133         more_mul_max =
 134                 min_t(uint32_t,
 135                       more_mul_max,
 136                       limits->max_pll_op_freq_hz
 137                       / (pll->ext_clk_freq_hz / pll->pre_pll_clk_div * mul));
 138         dev_dbg(dev, "more_mul_max: max_pll_op_freq_hz check: %d\n",
 139                 more_mul_max);
 140         /* Don't go above the division capability of op sys clock divider. */
 141         more_mul_max = min(more_mul_max,
 142                            limits->op.max_sys_clk_div * pll->pre_pll_clk_div
 143                            / div);
 144         dev_dbg(dev, "more_mul_max: max_op_sys_clk_div check: %d\n",
 145                 more_mul_max);
 146         /* Ensure we won't go above min_pll_multiplier. */
 147         more_mul_max = min(more_mul_max,
 148                            DIV_ROUND_UP(limits->max_pll_multiplier, mul));
 149         dev_dbg(dev, "more_mul_max: min_pll_multiplier check: %d\n",
 150                 more_mul_max);
 151
 152         /* Ensure we won't go below min_pll_op_freq_hz. */
 153         more_mul_min = DIV_ROUND_UP(limits->min_pll_op_freq_hz,
 154                                     pll->ext_clk_freq_hz / pll->pre_pll_clk_div
 155                                     * mul);
 156         dev_dbg(dev, "more_mul_min: min_pll_op_freq_hz check: %d\n",
 157                 more_mul_min);
 158         /* Ensure we won't go below min_pll_multiplier. */
 159         more_mul_min = max(more_mul_min,
 160                            DIV_ROUND_UP(limits->min_pll_multiplier, mul));
 161         dev_dbg(dev, "more_mul_min: min_pll_multiplier check: %d\n",
 162                 more_mul_min);
 163
 164         if (more_mul_min > more_mul_max) {
 165                 dev_dbg(dev,
 166                         "unable to compute more_mul_min and more_mul_max\n");
 167                 return -EINVAL;
 168         }
 169
 170         more_mul_factor = lcm(div, pll->pre_pll_clk_div) / div;
 171         dev_dbg(dev, "more_mul_factor: %d\n", more_mul_factor);
 172         more_mul_factor = lcm(more_mul_factor, limits->op.min_sys_clk_div);
 173         dev_dbg(dev, "more_mul_factor: min_op_sys_clk_div: %d\n",
 174                 more_mul_factor);
 175         i = roundup(more_mul_min, more_mul_factor);
 176         if (!is_one_or_even(i))
 177                 i <<= 1;
 178
 179         dev_dbg(dev, "final more_mul: %d\n", i);
 180         if (i > more_mul_max) {
 181                 dev_dbg(dev, "final more_mul is bad, max %d\n", more_mul_max);
 182                 return -EINVAL;
 183         }
 184
 185         pll->pll_multiplier = mul * i;
 186         pll->op_sys_clk_div = div * i / pll->pre_pll_clk_div;
 187         dev_dbg(dev, "op_sys_clk_div: %d\n", pll->op_sys_clk_div);
 188
 189         pll->pll_ip_clk_freq_hz = pll->ext_clk_freq_hz
 190                 / pll->pre_pll_clk_div;
 191
 192         pll->pll_op_clk_freq_hz = pll->pll_ip_clk_freq_hz
 193                 * pll->pll_multiplier;
 194
 195         /* Derive pll_op_clk_freq_hz. */
 196         pll->op_sys_clk_freq_hz =
 197                 pll->pll_op_clk_freq_hz / pll->op_sys_clk_div;
 198
 199         pll->op_pix_clk_div = pll->bits_per_pixel;
 200         dev_dbg(dev, "op_pix_clk_div: %d\n", pll->op_pix_clk_div);
 201
 202         pll->op_pix_clk_freq_hz =
 203                 pll->op_sys_clk_freq_hz / pll->op_pix_clk_div;
 204
 205         /*
 206          * Some sensors perform analogue binning and some do this
 207          * digitally. The ones doing this digitally can be roughly be
 208          * found out using this formula. The ones doing this digitally
 209          * should run at higher clock rate, so smaller divisor is used
 210          * on video timing side.
 211          */
 212         if (limits->min_line_length_pck_bin > limits->min_line_length_pck
 213             / pll->binning_horizontal)
 214                 vt_op_binning_div = pll->binning_horizontal;
 215         else
 216                 vt_op_binning_div = 1;
 217         dev_dbg(dev, "vt_op_binning_div: %d\n", vt_op_binning_div);
 218
 219         /*
 220          * Profile 2 supports vt_pix_clk_div E [4, 10]
 221          *
 222          * Horizontal binning can be used as a base for difference in
 223          * divisors. One must make sure that horizontal blanking is
 224          * enough to accommodate the CSI-2 sync codes.
 225          *
 226          * Take scaling factor into account as well.
 227          *
 228          * Find absolute limits for the factor of vt divider.
 229          */
 230         dev_dbg(dev, "scale_m: %d\n", pll->scale_m);
 231         min_vt_div = DIV_ROUND_UP(pll->op_pix_clk_div * pll->op_sys_clk_div
 232                                   * pll->scale_n,
 233                                   lane_op_clock_ratio * vt_op_binning_div
 234                                   * pll->scale_m);
 235
 236         /* Find smallest and biggest allowed vt divisor. */
 237         dev_dbg(dev, "min_vt_div: %d\n", min_vt_div);
 238         min_vt_div = max(min_vt_div,
 239                          DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 240                                       limits->vt.max_pix_clk_freq_hz));
 241         dev_dbg(dev, "min_vt_div: max_vt_pix_clk_freq_hz: %d\n",
 242                 min_vt_div);
 243         min_vt_div = max_t(uint32_t, min_vt_div,
 244                            limits->vt.min_pix_clk_div
 245                            * limits->vt.min_sys_clk_div);
 246         dev_dbg(dev, "min_vt_div: min_vt_clk_div: %d\n", min_vt_div);
 247
 248         max_vt_div = limits->vt.max_sys_clk_div * limits->vt.max_pix_clk_div;
 249         dev_dbg(dev, "max_vt_div: %d\n", max_vt_div);
 250         max_vt_div = min(max_vt_div,
 251                          DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 252                                       limits->vt.min_pix_clk_freq_hz));
 253         dev_dbg(dev, "max_vt_div: min_vt_pix_clk_freq_hz: %d\n",
 254                 max_vt_div);
 255
 256         /*
 257          * Find limitsits for sys_clk_div. Not all values are possible
 258          * with all values of pix_clk_div.
 259          */
 260         min_sys_div = limits->vt.min_sys_clk_div;
 261         dev_dbg(dev, "min_sys_div: %d\n", min_sys_div);
 262         min_sys_div = max(min_sys_div,
 263                           DIV_ROUND_UP(min_vt_div,
 264                                        limits->vt.max_pix_clk_div));
 265         dev_dbg(dev, "min_sys_div: max_vt_pix_clk_div: %d\n", min_sys_div);
 266         min_sys_div = max(min_sys_div,
 267                           pll->pll_op_clk_freq_hz
 268                           / limits->vt.max_sys_clk_freq_hz);
 269         dev_dbg(dev, "min_sys_div: max_pll_op_clk_freq_hz: %d\n", min_sys_div);
 270         min_sys_div = clk_div_even_up(min_sys_div);
 271         dev_dbg(dev, "min_sys_div: one or even: %d\n", min_sys_div);
 272
 273         max_sys_div = limits->vt.max_sys_clk_div;
 274         dev_dbg(dev, "max_sys_div: %d\n", max_sys_div);
 275         max_sys_div = min(max_sys_div,
 276                           DIV_ROUND_UP(max_vt_div,
 277                                        limits->vt.min_pix_clk_div));
 278         dev_dbg(dev, "max_sys_div: min_vt_pix_clk_div: %d\n", max_sys_div);
 279         max_sys_div = min(max_sys_div,
 280                           DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 281                                        limits->vt.min_pix_clk_freq_hz));
 282         dev_dbg(dev, "max_sys_div: min_vt_pix_clk_freq_hz: %d\n", max_sys_div);
 283
 284         /*
 285          * Find pix_div such that a legal pix_div * sys_div results
 286          * into a value which is not smaller than div, the desired
 287          * divisor.
 288          */
 289         for (vt_div = min_vt_div; vt_div <= max_vt_div;
 290              vt_div += 2 - (vt_div & 1)) {
 291                 for (sys_div = min_sys_div;
 292                      sys_div <= max_sys_div;
 293                      sys_div += 2 - (sys_div & 1)) {
 294                         uint16_t pix_div = DIV_ROUND_UP(vt_div, sys_div);
 295
 296                         if (pix_div < limits->vt.min_pix_clk_div
 297                             || pix_div > limits->vt.max_pix_clk_div) {
 298                                 dev_dbg(dev,
 299                                         "pix_div %d too small or too big (%d--%d)\n",
 300                                         pix_div,
 301                                         limits->vt.min_pix_clk_div,
 302                                         limits->vt.max_pix_clk_div);
 303                                 continue;
 304                         }
 305
 306                         /* Check if this one is better. */
 307                         if (pix_div * sys_div
 308                             <= roundup(min_vt_div, best_pix_div))
 309                                 best_pix_div = pix_div;
 310                 }
 311                 if (best_pix_div < INT_MAX >> 1)
 312                         break;
 313         }
 314
 315         pll->vt_sys_clk_div = DIV_ROUND_UP(min_vt_div, best_pix_div);
 316         pll->vt_pix_clk_div = best_pix_div;
 317
 318         pll->vt_sys_clk_freq_hz =
 319                 pll->pll_op_clk_freq_hz / pll->vt_sys_clk_div;
 320         pll->vt_pix_clk_freq_hz =
 321                 pll->vt_sys_clk_freq_hz / pll->vt_pix_clk_div;
 322
 323         pll->pixel_rate_csi =
 324                 pll->op_pix_clk_freq_hz * lane_op_clock_ratio;
 325
 326         rval = bounds_check(dev, pll->pll_ip_clk_freq_hz,
 327                             limits->min_pll_ip_freq_hz,
 328                             limits->max_pll_ip_freq_hz,
 329                             "pll_ip_clk_freq_hz");
 330         if (!rval)
 331                 rval = bounds_check(
 332                         dev, pll->pll_multiplier,
 333                         limits->min_pll_multiplier, limits->max_pll_multiplier,
 334                         "pll_multiplier");
 335         if (!rval)
 336                 rval = bounds_check(
 337                         dev, pll->pll_op_clk_freq_hz,
 338                         limits->min_pll_op_freq_hz, limits->max_pll_op_freq_hz,
 339                         "pll_op_clk_freq_hz");
 340         if (!rval)
 341                 rval = bounds_check(
 342                         dev, pll->op_sys_clk_div,
 343                         limits->op.min_sys_clk_div, limits->op.max_sys_clk_div,
 344                         "op_sys_clk_div");
 345         if (!rval)
 346                 rval = bounds_check(
 347                         dev, pll->op_pix_clk_div,
 348                         limits->op.min_pix_clk_div, limits->op.max_pix_clk_div,
 349                         "op_pix_clk_div");
 350         if (!rval)
 351                 rval = bounds_check(
 352                         dev, pll->op_sys_clk_freq_hz,
 353                         limits->op.min_sys_clk_freq_hz,
 354                         limits->op.max_sys_clk_freq_hz,
 355                         "op_sys_clk_freq_hz");
 356         if (!rval)
 357                 rval = bounds_check(
 358                         dev, pll->op_pix_clk_freq_hz,
 359                         limits->op.min_pix_clk_freq_hz,
 360                         limits->op.max_pix_clk_freq_hz,
 361                         "op_pix_clk_freq_hz");
 362         if (!rval)
 363                 rval = bounds_check(
 364                         dev, pll->vt_sys_clk_freq_hz,
 365                         limits->vt.min_sys_clk_freq_hz,
 366                         limits->vt.max_sys_clk_freq_hz,
 367                         "vt_sys_clk_freq_hz");
 368         if (!rval)
 369                 rval = bounds_check(
 370                         dev, pll->vt_pix_clk_freq_hz,
 371                         limits->vt.min_pix_clk_freq_hz,
 372                         limits->vt.max_pix_clk_freq_hz,
 373                         "vt_pix_clk_freq_hz");
 374
 375         return rval;
 376 }
 377
 378 int smiapp_pll_calculate(struct device *dev,
 379                          const struct smiapp_pll_limits *limits,
 380                          struct smiapp_pll *pll)
 381 {
 382         uint16_t min_pre_pll_clk_div;
 383         uint16_t max_pre_pll_clk_div;
 384         uint32_t lane_op_clock_ratio;
 385         uint32_t mul, div;
 386         unsigned int i;
 387         int rval = -EINVAL;
 388
 389         if (pll->flags & SMIAPP_PLL_FLAG_OP_PIX_CLOCK_PER_LANE)
 390                 lane_op_clock_ratio = pll->csi2.lanes;
 391         else
 392                 lane_op_clock_ratio = 1;
 393         dev_dbg(dev, "lane_op_clock_ratio: %d\n", lane_op_clock_ratio);
 394
 395         dev_dbg(dev, "binning: %dx%d\n", pll->binning_horizontal,
 396                 pll->binning_vertical);
 397
 398         switch (pll->bus_type) {
 399         case SMIAPP_PLL_BUS_TYPE_CSI2:
 400                 /* CSI transfers 2 bits per clock per lane; thus times 2 */
 401                 pll->pll_op_clk_freq_hz = pll->link_freq * 2
 402                         * (pll->csi2.lanes / lane_op_clock_ratio);
 403                 break;
 404         case SMIAPP_PLL_BUS_TYPE_PARALLEL:
 405                 pll->pll_op_clk_freq_hz = pll->link_freq * pll->bits_per_pixel
 406                         / DIV_ROUND_UP(pll->bits_per_pixel,
 407                                        pll->parallel.bus_width);
 408                 break;
 409         default:
 410                 return -EINVAL;
 411         }
 412
 413         /* Figure out limits for pre-pll divider based on extclk */
 414         dev_dbg(dev, "min / max pre_pll_clk_div: %d / %d\n",
 415                 limits->min_pre_pll_clk_div, limits->max_pre_pll_clk_div);
 416         max_pre_pll_clk_div =
 417                 min_t(uint16_t, limits->max_pre_pll_clk_div,
 418                       clk_div_even(pll->ext_clk_freq_hz /
 419                                    limits->min_pll_ip_freq_hz));
 420         min_pre_pll_clk_div =
 421                 max_t(uint16_t, limits->min_pre_pll_clk_div,
 422                       clk_div_even_up(
 423                               DIV_ROUND_UP(pll->ext_clk_freq_hz,
 424                                            limits->max_pll_ip_freq_hz)));
 425         dev_dbg(dev, "pre-pll check: min / max pre_pll_clk_div: %d / %d\n",
 426                 min_pre_pll_clk_div, max_pre_pll_clk_div);
 427
 428         i = gcd(pll->pll_op_clk_freq_hz, pll->ext_clk_freq_hz);
 429         mul = div_u64(pll->pll_op_clk_freq_hz, i);
 430         div = pll->ext_clk_freq_hz / i;
 431         dev_dbg(dev, "mul %d / div %d\n", mul, div);
 432
 433         min_pre_pll_clk_div =
 434                 max_t(uint16_t, min_pre_pll_clk_div,
 435                       clk_div_even_up(
 436                               DIV_ROUND_UP(mul * pll->ext_clk_freq_hz,
 437                                            limits->max_pll_op_freq_hz)));
 438         dev_dbg(dev, "pll_op check: min / max pre_pll_clk_div: %d / %d\n",
 439                 min_pre_pll_clk_div, max_pre_pll_clk_div);
 440
 441         for (pll->pre_pll_clk_div = min_pre_pll_clk_div;
 442              pll->pre_pll_clk_div <= max_pre_pll_clk_div;
 443              pll->pre_pll_clk_div += 2 - (pll->pre_pll_clk_div & 1)) {
 444                 rval = __smiapp_pll_calculate(dev, limits, pll, mul, div,
 445                                               lane_op_clock_ratio);
 446                 if (rval)
 447                         continue;
 448
 449                 print_pll(dev, pll);
 450                 return 0;
 451         }
 452
 453         dev_info(dev, "unable to compute pre_pll divisor\n");
 454         return rval;
 455 }
 456 EXPORT_SYMBOL_GPL(smiapp_pll_calculate);
 457
 458 MODULE_AUTHOR("Sakari Ailus <sakari.ailus@iki.fi>");
 459 MODULE_DESCRIPTION("Generic SMIA/SMIA++ PLL calculator");
 460 MODULE_LICENSE("GPL");