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@maxwell.research.nokia.com>
   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_warn(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 int smiapp_pll_calculate(struct device *dev, struct smiapp_pll_limits *limits,
  91                          struct smiapp_pll *pll)
  92 {
  93         uint32_t sys_div;
  94         uint32_t best_pix_div = INT_MAX >> 1;
  95         uint32_t vt_op_binning_div;
  96         uint32_t lane_op_clock_ratio;
  97         uint32_t mul, div;
  98         uint32_t more_mul_min, more_mul_max;
  99         uint32_t more_mul_factor;
 100         uint32_t min_vt_div, max_vt_div, vt_div;
 101         uint32_t min_sys_div, max_sys_div;
 102         unsigned int i;
 103         int rval;
 104
 105         if (pll->flags & SMIAPP_PLL_FLAG_OP_PIX_CLOCK_PER_LANE)
 106                 lane_op_clock_ratio = pll->lanes;
 107         else
 108                 lane_op_clock_ratio = 1;
 109         dev_dbg(dev, "lane_op_clock_ratio: %d\n", lane_op_clock_ratio);
 110
 111         dev_dbg(dev, "binning: %dx%d\n", pll->binning_horizontal,
 112                 pll->binning_vertical);
 113
 114         /* CSI transfers 2 bits per clock per lane; thus times 2 */
 115         pll->pll_op_clk_freq_hz = pll->link_freq * 2
 116                 * (pll->lanes / lane_op_clock_ratio);
 117
 118         /* Figure out limits for pre-pll divider based on extclk */
 119         dev_dbg(dev, "min / max pre_pll_clk_div: %d / %d\n",
 120                 limits->min_pre_pll_clk_div, limits->max_pre_pll_clk_div);
 121         limits->max_pre_pll_clk_div =
 122                 min_t(uint16_t, limits->max_pre_pll_clk_div,
 123                       clk_div_even(pll->ext_clk_freq_hz /
 124                                    limits->min_pll_ip_freq_hz));
 125         limits->min_pre_pll_clk_div =
 126                 max_t(uint16_t, limits->min_pre_pll_clk_div,
 127                       clk_div_even_up(
 128                               DIV_ROUND_UP(pll->ext_clk_freq_hz,
 129                                            limits->max_pll_ip_freq_hz)));
 130         dev_dbg(dev, "pre-pll check: min / max pre_pll_clk_div: %d / %d\n",
 131                 limits->min_pre_pll_clk_div, limits->max_pre_pll_clk_div);
 132
 133         i = gcd(pll->pll_op_clk_freq_hz, pll->ext_clk_freq_hz);
 134         mul = div_u64(pll->pll_op_clk_freq_hz, i);
 135         div = pll->ext_clk_freq_hz / i;
 136         dev_dbg(dev, "mul %d / div %d\n", mul, div);
 137
 138         limits->min_pre_pll_clk_div =
 139                 max_t(uint16_t, limits->min_pre_pll_clk_div,
 140                       clk_div_even_up(
 141                               DIV_ROUND_UP(mul * pll->ext_clk_freq_hz,
 142                                            limits->max_pll_op_freq_hz)));
 143         dev_dbg(dev, "pll_op check: min / max pre_pll_clk_div: %d / %d\n",
 144                 limits->min_pre_pll_clk_div, limits->max_pre_pll_clk_div);
 145
 146         if (limits->min_pre_pll_clk_div > limits->max_pre_pll_clk_div) {
 147                 dev_err(dev, "unable to compute pre_pll divisor\n");
 148                 return -EINVAL;
 149         }
 150
 151         pll->pre_pll_clk_div = limits->min_pre_pll_clk_div;
 152
 153         /*
 154          * Get pre_pll_clk_div so that our pll_op_clk_freq_hz won't be
 155          * too high.
 156          */
 157         dev_dbg(dev, "pre_pll_clk_div %d\n", pll->pre_pll_clk_div);
 158
 159         /* Don't go above max pll multiplier. */
 160         more_mul_max = limits->max_pll_multiplier / mul;
 161         dev_dbg(dev, "more_mul_max: max_pll_multiplier check: %d\n",
 162                 more_mul_max);
 163         /* Don't go above max pll op frequency. */
 164         more_mul_max =
 165                 min_t(int,
 166                       more_mul_max,
 167                       limits->max_pll_op_freq_hz
 168                       / (pll->ext_clk_freq_hz / pll->pre_pll_clk_div * mul));
 169         dev_dbg(dev, "more_mul_max: max_pll_op_freq_hz check: %d\n",
 170                 more_mul_max);
 171         /* Don't go above the division capability of op sys clock divider. */
 172         more_mul_max = min(more_mul_max,
 173                            limits->max_op_sys_clk_div * pll->pre_pll_clk_div
 174                            / div);
 175         dev_dbg(dev, "more_mul_max: max_op_sys_clk_div check: %d\n",
 176                 more_mul_max);
 177         /* Ensure we won't go above min_pll_multiplier. */
 178         more_mul_max = min(more_mul_max,
 179                            DIV_ROUND_UP(limits->max_pll_multiplier, mul));
 180         dev_dbg(dev, "more_mul_max: min_pll_multiplier check: %d\n",
 181                 more_mul_max);
 182
 183         /* Ensure we won't go below min_pll_op_freq_hz. */
 184         more_mul_min = DIV_ROUND_UP(limits->min_pll_op_freq_hz,
 185                                     pll->ext_clk_freq_hz / pll->pre_pll_clk_div
 186                                     * mul);
 187         dev_dbg(dev, "more_mul_min: min_pll_op_freq_hz check: %d\n",
 188                 more_mul_min);
 189         /* Ensure we won't go below min_pll_multiplier. */
 190         more_mul_min = max(more_mul_min,
 191                            DIV_ROUND_UP(limits->min_pll_multiplier, mul));
 192         dev_dbg(dev, "more_mul_min: min_pll_multiplier check: %d\n",
 193                 more_mul_min);
 194
 195         if (more_mul_min > more_mul_max) {
 196                 dev_warn(dev,
 197                          "unable to compute more_mul_min and more_mul_max");
 198                 return -EINVAL;
 199         }
 200
 201         more_mul_factor = lcm(div, pll->pre_pll_clk_div) / div;
 202         dev_dbg(dev, "more_mul_factor: %d\n", more_mul_factor);
 203         more_mul_factor = lcm(more_mul_factor, limits->min_op_sys_clk_div);
 204         dev_dbg(dev, "more_mul_factor: min_op_sys_clk_div: %d\n",
 205                 more_mul_factor);
 206         i = roundup(more_mul_min, more_mul_factor);
 207         if (!is_one_or_even(i))
 208                 i <<= 1;
 209
 210         dev_dbg(dev, "final more_mul: %d\n", i);
 211         if (i > more_mul_max) {
 212                 dev_warn(dev, "final more_mul is bad, max %d", more_mul_max);
 213                 return -EINVAL;
 214         }
 215
 216         pll->pll_multiplier = mul * i;
 217         pll->op_sys_clk_div = div * i / pll->pre_pll_clk_div;
 218         dev_dbg(dev, "op_sys_clk_div: %d\n", pll->op_sys_clk_div);
 219
 220         pll->pll_ip_clk_freq_hz = pll->ext_clk_freq_hz
 221                 / pll->pre_pll_clk_div;
 222
 223         pll->pll_op_clk_freq_hz = pll->pll_ip_clk_freq_hz
 224                 * pll->pll_multiplier;
 225
 226         /* Derive pll_op_clk_freq_hz. */
 227         pll->op_sys_clk_freq_hz =
 228                 pll->pll_op_clk_freq_hz / pll->op_sys_clk_div;
 229
 230         pll->op_pix_clk_div = pll->bits_per_pixel;
 231         dev_dbg(dev, "op_pix_clk_div: %d\n", pll->op_pix_clk_div);
 232
 233         pll->op_pix_clk_freq_hz =
 234                 pll->op_sys_clk_freq_hz / pll->op_pix_clk_div;
 235
 236         /*
 237          * Some sensors perform analogue binning and some do this
 238          * digitally. The ones doing this digitally can be roughly be
 239          * found out using this formula. The ones doing this digitally
 240          * should run at higher clock rate, so smaller divisor is used
 241          * on video timing side.
 242          */
 243         if (limits->min_line_length_pck_bin > limits->min_line_length_pck
 244             / pll->binning_horizontal)
 245                 vt_op_binning_div = pll->binning_horizontal;
 246         else
 247                 vt_op_binning_div = 1;
 248         dev_dbg(dev, "vt_op_binning_div: %d\n", vt_op_binning_div);
 249
 250         /*
 251          * Profile 2 supports vt_pix_clk_div E [4, 10]
 252          *
 253          * Horizontal binning can be used as a base for difference in
 254          * divisors. One must make sure that horizontal blanking is
 255          * enough to accommodate the CSI-2 sync codes.
 256          *
 257          * Take scaling factor into account as well.
 258          *
 259          * Find absolute limits for the factor of vt divider.
 260          */
 261         dev_dbg(dev, "scale_m: %d\n", pll->scale_m);
 262         min_vt_div = DIV_ROUND_UP(pll->op_pix_clk_div * pll->op_sys_clk_div
 263                                   * pll->scale_n,
 264                                   lane_op_clock_ratio * vt_op_binning_div
 265                                   * pll->scale_m);
 266
 267         /* Find smallest and biggest allowed vt divisor. */
 268         dev_dbg(dev, "min_vt_div: %d\n", min_vt_div);
 269         min_vt_div = max(min_vt_div,
 270                          DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 271                                       limits->max_vt_pix_clk_freq_hz));
 272         dev_dbg(dev, "min_vt_div: max_vt_pix_clk_freq_hz: %d\n",
 273                 min_vt_div);
 274         min_vt_div = max_t(uint32_t, min_vt_div,
 275                            limits->min_vt_pix_clk_div
 276                            * limits->min_vt_sys_clk_div);
 277         dev_dbg(dev, "min_vt_div: min_vt_clk_div: %d\n", min_vt_div);
 278
 279         max_vt_div = limits->max_vt_sys_clk_div * limits->max_vt_pix_clk_div;
 280         dev_dbg(dev, "max_vt_div: %d\n", max_vt_div);
 281         max_vt_div = min(max_vt_div,
 282                          DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 283                                       limits->min_vt_pix_clk_freq_hz));
 284         dev_dbg(dev, "max_vt_div: min_vt_pix_clk_freq_hz: %d\n",
 285                 max_vt_div);
 286
 287         /*
 288          * Find limitsits for sys_clk_div. Not all values are possible
 289          * with all values of pix_clk_div.
 290          */
 291         min_sys_div = limits->min_vt_sys_clk_div;
 292         dev_dbg(dev, "min_sys_div: %d\n", min_sys_div);
 293         min_sys_div = max(min_sys_div,
 294                           DIV_ROUND_UP(min_vt_div,
 295                                        limits->max_vt_pix_clk_div));
 296         dev_dbg(dev, "min_sys_div: max_vt_pix_clk_div: %d\n", min_sys_div);
 297         min_sys_div = max(min_sys_div,
 298                           pll->pll_op_clk_freq_hz
 299                           / limits->max_vt_sys_clk_freq_hz);
 300         dev_dbg(dev, "min_sys_div: max_pll_op_clk_freq_hz: %d\n", min_sys_div);
 301         min_sys_div = clk_div_even_up(min_sys_div);
 302         dev_dbg(dev, "min_sys_div: one or even: %d\n", min_sys_div);
 303
 304         max_sys_div = limits->max_vt_sys_clk_div;
 305         dev_dbg(dev, "max_sys_div: %d\n", max_sys_div);
 306         max_sys_div = min(max_sys_div,
 307                           DIV_ROUND_UP(max_vt_div,
 308                                        limits->min_vt_pix_clk_div));
 309         dev_dbg(dev, "max_sys_div: min_vt_pix_clk_div: %d\n", max_sys_div);
 310         max_sys_div = min(max_sys_div,
 311                           DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 312                                        limits->min_vt_pix_clk_freq_hz));
 313         dev_dbg(dev, "max_sys_div: min_vt_pix_clk_freq_hz: %d\n", max_sys_div);
 314
 315         /*
 316          * Find pix_div such that a legal pix_div * sys_div results
 317          * into a value which is not smaller than div, the desired
 318          * divisor.
 319          */
 320         for (vt_div = min_vt_div; vt_div <= max_vt_div;
 321              vt_div += 2 - (vt_div & 1)) {
 322                 for (sys_div = min_sys_div;
 323                      sys_div <= max_sys_div;
 324                      sys_div += 2 - (sys_div & 1)) {
 325                         int pix_div = DIV_ROUND_UP(vt_div, sys_div);
 326
 327                         if (pix_div < limits->min_vt_pix_clk_div
 328                             || pix_div > limits->max_vt_pix_clk_div) {
 329                                 dev_dbg(dev,
 330                                         "pix_div %d too small or too big (%d--%d)\n",
 331                                         pix_div,
 332                                         limits->min_vt_pix_clk_div,
 333                                         limits->max_vt_pix_clk_div);
 334                                 continue;
 335                         }
 336
 337                         /* Check if this one is better. */
 338                         if (pix_div * sys_div
 339                             <= roundup(min_vt_div, best_pix_div))
 340                                 best_pix_div = pix_div;
 341                 }
 342                 if (best_pix_div < INT_MAX >> 1)
 343                         break;
 344         }
 345
 346         pll->vt_sys_clk_div = DIV_ROUND_UP(min_vt_div, best_pix_div);
 347         pll->vt_pix_clk_div = best_pix_div;
 348
 349         pll->vt_sys_clk_freq_hz =
 350                 pll->pll_op_clk_freq_hz / pll->vt_sys_clk_div;
 351         pll->vt_pix_clk_freq_hz =
 352                 pll->vt_sys_clk_freq_hz / pll->vt_pix_clk_div;
 353
 354         pll->pixel_rate_csi =
 355                 pll->op_pix_clk_freq_hz * lane_op_clock_ratio;
 356
 357         print_pll(dev, pll);
 358
 359         rval = bounds_check(dev, pll->pre_pll_clk_div,
 360                             limits->min_pre_pll_clk_div,
 361                             limits->max_pre_pll_clk_div, "pre_pll_clk_div");
 362         if (!rval)
 363                 rval = bounds_check(
 364                         dev, pll->pll_ip_clk_freq_hz,
 365                         limits->min_pll_ip_freq_hz, limits->max_pll_ip_freq_hz,
 366                         "pll_ip_clk_freq_hz");
 367         if (!rval)
 368                 rval = bounds_check(
 369                         dev, pll->pll_multiplier,
 370                         limits->min_pll_multiplier, limits->max_pll_multiplier,
 371                         "pll_multiplier");
 372         if (!rval)
 373                 rval = bounds_check(
 374                         dev, pll->pll_op_clk_freq_hz,
 375                         limits->min_pll_op_freq_hz, limits->max_pll_op_freq_hz,
 376                         "pll_op_clk_freq_hz");
 377         if (!rval)
 378                 rval = bounds_check(
 379                         dev, pll->op_sys_clk_div,
 380                         limits->min_op_sys_clk_div, limits->max_op_sys_clk_div,
 381                         "op_sys_clk_div");
 382         if (!rval)
 383                 rval = bounds_check(
 384                         dev, pll->op_pix_clk_div,
 385                         limits->min_op_pix_clk_div, limits->max_op_pix_clk_div,
 386                         "op_pix_clk_div");
 387         if (!rval)
 388                 rval = bounds_check(
 389                         dev, pll->op_sys_clk_freq_hz,
 390                         limits->min_op_sys_clk_freq_hz,
 391                         limits->max_op_sys_clk_freq_hz,
 392                         "op_sys_clk_freq_hz");
 393         if (!rval)
 394                 rval = bounds_check(
 395                         dev, pll->op_pix_clk_freq_hz,
 396                         limits->min_op_pix_clk_freq_hz,
 397                         limits->max_op_pix_clk_freq_hz,
 398                         "op_pix_clk_freq_hz");
 399         if (!rval)
 400                 rval = bounds_check(
 401                         dev, pll->vt_sys_clk_freq_hz,
 402                         limits->min_vt_sys_clk_freq_hz,
 403                         limits->max_vt_sys_clk_freq_hz,
 404                         "vt_sys_clk_freq_hz");
 405         if (!rval)
 406                 rval = bounds_check(
 407                         dev, pll->vt_pix_clk_freq_hz,
 408                         limits->min_vt_pix_clk_freq_hz,
 409                         limits->max_vt_pix_clk_freq_hz,
 410                         "vt_pix_clk_freq_hz");
 411
 412         return rval;
 413 }
 414 EXPORT_SYMBOL_GPL(smiapp_pll_calculate);
 415
 416 MODULE_AUTHOR("Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>");
 417 MODULE_DESCRIPTION("Generic SMIA/SMIA++ PLL calculator");
 418 MODULE_LICENSE("GPL");