kernel/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
  19 #include <linux/device.h>
  20 #include <linux/gcd.h>
  21 #include <linux/lcm.h>
  22 #include <linux/module.h>
  23
  24 #include "smiapp-pll.h"
  25
  26 /* Return an even number or one. */
  27 static inline uint32_t clk_div_even(uint32_t a)
  28 {
  29         return max_t(uint32_t, 1, a & ~1);
  30 }
  31
  32 /* Return an even number or one. */
  33 static inline uint32_t clk_div_even_up(uint32_t a)
  34 {
  35         if (a == 1)
  36                 return 1;
  37         return (a + 1) & ~1;
  38 }
  39
  40 static inline uint32_t is_one_or_even(uint32_t a)
  41 {
  42         if (a == 1)
  43                 return 1;
  44         if (a & 1)
  45                 return 0;
  46
  47         return 1;
  48 }
  49
  50 static int bounds_check(struct device *dev, uint32_t val,
  51                         uint32_t min, uint32_t max, char *str)
  52 {
  53         if (val >= min && val <= max)
  54                 return 0;
  55
  56         dev_dbg(dev, "%s out of bounds: %d (%d--%d)\n", str, val, min, max);
  57
  58         return -EINVAL;
  59 }
  60
  61 static void print_pll(struct device *dev, struct smiapp_pll *pll)
  62 {
  63         dev_dbg(dev, "pre_pll_clk_div\t%u\n",  pll->pre_pll_clk_div);
  64         dev_dbg(dev, "pll_multiplier \t%u\n",  pll->pll_multiplier);
  65         if (!(pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)) {
  66                 dev_dbg(dev, "op_sys_clk_div \t%u\n", pll->op.sys_clk_div);
  67                 dev_dbg(dev, "op_pix_clk_div \t%u\n", pll->op.pix_clk_div);
  68         }
  69         dev_dbg(dev, "vt_sys_clk_div \t%u\n",  pll->vt.sys_clk_div);
  70         dev_dbg(dev, "vt_pix_clk_div \t%u\n",  pll->vt.pix_clk_div);
  71
  72         dev_dbg(dev, "ext_clk_freq_hz \t%u\n", pll->ext_clk_freq_hz);
  73         dev_dbg(dev, "pll_ip_clk_freq_hz \t%u\n", pll->pll_ip_clk_freq_hz);
  74         dev_dbg(dev, "pll_op_clk_freq_hz \t%u\n", pll->pll_op_clk_freq_hz);
  75         if (!(pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)) {
  76                 dev_dbg(dev, "op_sys_clk_freq_hz \t%u\n",
  77                         pll->op.sys_clk_freq_hz);
  78                 dev_dbg(dev, "op_pix_clk_freq_hz \t%u\n",
  79                         pll->op.pix_clk_freq_hz);
  80         }
  81         dev_dbg(dev, "vt_sys_clk_freq_hz \t%u\n", pll->vt.sys_clk_freq_hz);
  82         dev_dbg(dev, "vt_pix_clk_freq_hz \t%u\n", pll->vt.pix_clk_freq_hz);
  83 }
  84
  85 static int check_all_bounds(struct device *dev,
  86                             const struct smiapp_pll_limits *limits,
  87                             const struct smiapp_pll_branch_limits *op_limits,
  88                             struct smiapp_pll *pll,
  89                             struct smiapp_pll_branch *op_pll)
  90 {
  91         int rval;
  92
  93         rval = bounds_check(dev, pll->pll_ip_clk_freq_hz,
  94                             limits->min_pll_ip_freq_hz,
  95                             limits->max_pll_ip_freq_hz,
  96                             "pll_ip_clk_freq_hz");
  97         if (!rval)
  98                 rval = bounds_check(
  99                         dev, pll->pll_multiplier,
 100                         limits->min_pll_multiplier, limits->max_pll_multiplier,
 101                         "pll_multiplier");
 102         if (!rval)
 103                 rval = bounds_check(
 104                         dev, pll->pll_op_clk_freq_hz,
 105                         limits->min_pll_op_freq_hz, limits->max_pll_op_freq_hz,
 106                         "pll_op_clk_freq_hz");
 107         if (!rval)
 108                 rval = bounds_check(
 109                         dev, op_pll->sys_clk_div,
 110                         op_limits->min_sys_clk_div, op_limits->max_sys_clk_div,
 111                         "op_sys_clk_div");
 112         if (!rval)
 113                 rval = bounds_check(
 114                         dev, op_pll->sys_clk_freq_hz,
 115                         op_limits->min_sys_clk_freq_hz,
 116                         op_limits->max_sys_clk_freq_hz,
 117                         "op_sys_clk_freq_hz");
 118         if (!rval)
 119                 rval = bounds_check(
 120                         dev, op_pll->pix_clk_freq_hz,
 121                         op_limits->min_pix_clk_freq_hz,
 122                         op_limits->max_pix_clk_freq_hz,
 123                         "op_pix_clk_freq_hz");
 124
 125         /*
 126          * If there are no OP clocks, the VT clocks are contained in
 127          * the OP clock struct.
 128          */
 129         if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)
 130                 return rval;
 131
 132         if (!rval)
 133                 rval = bounds_check(
 134                         dev, pll->vt.sys_clk_freq_hz,
 135                         limits->vt.min_sys_clk_freq_hz,
 136                         limits->vt.max_sys_clk_freq_hz,
 137                         "vt_sys_clk_freq_hz");
 138         if (!rval)
 139                 rval = bounds_check(
 140                         dev, pll->vt.pix_clk_freq_hz,
 141                         limits->vt.min_pix_clk_freq_hz,
 142                         limits->vt.max_pix_clk_freq_hz,
 143                         "vt_pix_clk_freq_hz");
 144
 145         return rval;
 146 }
 147
 148 /*
 149  * Heuristically guess the PLL tree for a given common multiplier and
 150  * divisor. Begin with the operational timing and continue to video
 151  * timing once operational timing has been verified.
 152  *
 153  * @mul is the PLL multiplier and @div is the common divisor
 154  * (pre_pll_clk_div and op_sys_clk_div combined). The final PLL
 155  * multiplier will be a multiple of @mul.
 156  *
 157  * @return Zero on success, error code on error.
 158  */
 159 static int __smiapp_pll_calculate(
 160         struct device *dev, const struct smiapp_pll_limits *limits,
 161         const struct smiapp_pll_branch_limits *op_limits,
 162         struct smiapp_pll *pll, struct smiapp_pll_branch *op_pll, uint32_t mul,
 163         uint32_t div, uint32_t lane_op_clock_ratio)
 164 {
 165         uint32_t sys_div;
 166         uint32_t best_pix_div = INT_MAX >> 1;
 167         uint32_t vt_op_binning_div;
 168         /*
 169          * Higher multipliers (and divisors) are often required than
 170          * necessitated by the external clock and the output clocks.
 171          * There are limits for all values in the clock tree. These
 172          * are the minimum and maximum multiplier for mul.
 173          */
 174         uint32_t more_mul_min, more_mul_max;
 175         uint32_t more_mul_factor;
 176         uint32_t min_vt_div, max_vt_div, vt_div;
 177         uint32_t min_sys_div, max_sys_div;
 178         unsigned int i;
 179
 180         /*
 181          * Get pre_pll_clk_div so that our pll_op_clk_freq_hz won't be
 182          * too high.
 183          */
 184         dev_dbg(dev, "pre_pll_clk_div %u\n", pll->pre_pll_clk_div);
 185
 186         /* Don't go above max pll multiplier. */
 187         more_mul_max = limits->max_pll_multiplier / mul;
 188         dev_dbg(dev, "more_mul_max: max_pll_multiplier check: %u\n",
 189                 more_mul_max);
 190         /* Don't go above max pll op frequency. */
 191         more_mul_max =
 192                 min_t(uint32_t,
 193                       more_mul_max,
 194                       limits->max_pll_op_freq_hz
 195                       / (pll->ext_clk_freq_hz / pll->pre_pll_clk_div * mul));
 196         dev_dbg(dev, "more_mul_max: max_pll_op_freq_hz check: %u\n",
 197                 more_mul_max);
 198         /* Don't go above the division capability of op sys clock divider. */
 199         more_mul_max = min(more_mul_max,
 200                            op_limits->max_sys_clk_div * pll->pre_pll_clk_div
 201                            / div);
 202         dev_dbg(dev, "more_mul_max: max_op_sys_clk_div check: %u\n",
 203                 more_mul_max);
 204         /* Ensure we won't go above min_pll_multiplier. */
 205         more_mul_max = min(more_mul_max,
 206                            DIV_ROUND_UP(limits->max_pll_multiplier, mul));
 207         dev_dbg(dev, "more_mul_max: min_pll_multiplier check: %u\n",
 208                 more_mul_max);
 209
 210         /* Ensure we won't go below min_pll_op_freq_hz. */
 211         more_mul_min = DIV_ROUND_UP(limits->min_pll_op_freq_hz,
 212                                     pll->ext_clk_freq_hz / pll->pre_pll_clk_div
 213                                     * mul);
 214         dev_dbg(dev, "more_mul_min: min_pll_op_freq_hz check: %u\n",
 215                 more_mul_min);
 216         /* Ensure we won't go below min_pll_multiplier. */
 217         more_mul_min = max(more_mul_min,
 218                            DIV_ROUND_UP(limits->min_pll_multiplier, mul));
 219         dev_dbg(dev, "more_mul_min: min_pll_multiplier check: %u\n",
 220                 more_mul_min);
 221
 222         if (more_mul_min > more_mul_max) {
 223                 dev_dbg(dev,
 224                         "unable to compute more_mul_min and more_mul_max\n");
 225                 return -EINVAL;
 226         }
 227
 228         more_mul_factor = lcm(div, pll->pre_pll_clk_div) / div;
 229         dev_dbg(dev, "more_mul_factor: %u\n", more_mul_factor);
 230         more_mul_factor = lcm(more_mul_factor, op_limits->min_sys_clk_div);
 231         dev_dbg(dev, "more_mul_factor: min_op_sys_clk_div: %d\n",
 232                 more_mul_factor);
 233         i = roundup(more_mul_min, more_mul_factor);
 234         if (!is_one_or_even(i))
 235                 i <<= 1;
 236
 237         dev_dbg(dev, "final more_mul: %u\n", i);
 238         if (i > more_mul_max) {
 239                 dev_dbg(dev, "final more_mul is bad, max %u\n", more_mul_max);
 240                 return -EINVAL;
 241         }
 242
 243         pll->pll_multiplier = mul * i;
 244         op_pll->sys_clk_div = div * i / pll->pre_pll_clk_div;
 245         dev_dbg(dev, "op_sys_clk_div: %u\n", op_pll->sys_clk_div);
 246
 247         pll->pll_ip_clk_freq_hz = pll->ext_clk_freq_hz
 248                 / pll->pre_pll_clk_div;
 249
 250         pll->pll_op_clk_freq_hz = pll->pll_ip_clk_freq_hz
 251                 * pll->pll_multiplier;
 252
 253         /* Derive pll_op_clk_freq_hz. */
 254         op_pll->sys_clk_freq_hz =
 255                 pll->pll_op_clk_freq_hz / op_pll->sys_clk_div;
 256
 257         op_pll->pix_clk_div = pll->bits_per_pixel;
 258         dev_dbg(dev, "op_pix_clk_div: %u\n", op_pll->pix_clk_div);
 259
 260         op_pll->pix_clk_freq_hz =
 261                 op_pll->sys_clk_freq_hz / op_pll->pix_clk_div;
 262
 263         if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS) {
 264                 /* No OP clocks --- VT clocks are used instead. */
 265                 goto out_skip_vt_calc;
 266         }
 267
 268         /*
 269          * Some sensors perform analogue binning and some do this
 270          * digitally. The ones doing this digitally can be roughly be
 271          * found out using this formula. The ones doing this digitally
 272          * should run at higher clock rate, so smaller divisor is used
 273          * on video timing side.
 274          */
 275         if (limits->min_line_length_pck_bin > limits->min_line_length_pck
 276             / pll->binning_horizontal)
 277                 vt_op_binning_div = pll->binning_horizontal;
 278         else
 279                 vt_op_binning_div = 1;
 280         dev_dbg(dev, "vt_op_binning_div: %u\n", vt_op_binning_div);
 281
 282         /*
 283          * Profile 2 supports vt_pix_clk_div E [4, 10]
 284          *
 285          * Horizontal binning can be used as a base for difference in
 286          * divisors. One must make sure that horizontal blanking is
 287          * enough to accommodate the CSI-2 sync codes.
 288          *
 289          * Take scaling factor into account as well.
 290          *
 291          * Find absolute limits for the factor of vt divider.
 292          */
 293         dev_dbg(dev, "scale_m: %u\n", pll->scale_m);
 294         min_vt_div = DIV_ROUND_UP(op_pll->pix_clk_div * op_pll->sys_clk_div
 295                                   * pll->scale_n,
 296                                   lane_op_clock_ratio * vt_op_binning_div
 297                                   * pll->scale_m);
 298
 299         /* Find smallest and biggest allowed vt divisor. */
 300         dev_dbg(dev, "min_vt_div: %u\n", min_vt_div);
 301         min_vt_div = max(min_vt_div,
 302                          DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 303                                       limits->vt.max_pix_clk_freq_hz));
 304         dev_dbg(dev, "min_vt_div: max_vt_pix_clk_freq_hz: %u\n",
 305                 min_vt_div);
 306         min_vt_div = max_t(uint32_t, min_vt_div,
 307                            limits->vt.min_pix_clk_div
 308                            * limits->vt.min_sys_clk_div);
 309         dev_dbg(dev, "min_vt_div: min_vt_clk_div: %u\n", min_vt_div);
 310
 311         max_vt_div = limits->vt.max_sys_clk_div * limits->vt.max_pix_clk_div;
 312         dev_dbg(dev, "max_vt_div: %u\n", max_vt_div);
 313         max_vt_div = min(max_vt_div,
 314                          DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 315                                       limits->vt.min_pix_clk_freq_hz));
 316         dev_dbg(dev, "max_vt_div: min_vt_pix_clk_freq_hz: %u\n",
 317                 max_vt_div);
 318
 319         /*
 320          * Find limitsits for sys_clk_div. Not all values are possible
 321          * with all values of pix_clk_div.
 322          */
 323         min_sys_div = limits->vt.min_sys_clk_div;
 324         dev_dbg(dev, "min_sys_div: %u\n", min_sys_div);
 325         min_sys_div = max(min_sys_div,
 326                           DIV_ROUND_UP(min_vt_div,
 327                                        limits->vt.max_pix_clk_div));
 328         dev_dbg(dev, "min_sys_div: max_vt_pix_clk_div: %u\n", min_sys_div);
 329         min_sys_div = max(min_sys_div,
 330                           pll->pll_op_clk_freq_hz
 331                           / limits->vt.max_sys_clk_freq_hz);
 332         dev_dbg(dev, "min_sys_div: max_pll_op_clk_freq_hz: %u\n", min_sys_div);
 333         min_sys_div = clk_div_even_up(min_sys_div);
 334         dev_dbg(dev, "min_sys_div: one or even: %u\n", min_sys_div);
 335
 336         max_sys_div = limits->vt.max_sys_clk_div;
 337         dev_dbg(dev, "max_sys_div: %u\n", max_sys_div);
 338         max_sys_div = min(max_sys_div,
 339                           DIV_ROUND_UP(max_vt_div,
 340                                        limits->vt.min_pix_clk_div));
 341         dev_dbg(dev, "max_sys_div: min_vt_pix_clk_div: %u\n", max_sys_div);
 342         max_sys_div = min(max_sys_div,
 343                           DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
 344                                        limits->vt.min_pix_clk_freq_hz));
 345         dev_dbg(dev, "max_sys_div: min_vt_pix_clk_freq_hz: %u\n", max_sys_div);
 346
 347         /*
 348          * Find pix_div such that a legal pix_div * sys_div results
 349          * into a value which is not smaller than div, the desired
 350          * divisor.
 351          */
 352         for (vt_div = min_vt_div; vt_div <= max_vt_div;
 353              vt_div += 2 - (vt_div & 1)) {
 354                 for (sys_div = min_sys_div;
 355                      sys_div <= max_sys_div;
 356                      sys_div += 2 - (sys_div & 1)) {
 357                         uint16_t pix_div = DIV_ROUND_UP(vt_div, sys_div);
 358
 359                         if (pix_div < limits->vt.min_pix_clk_div
 360                             || pix_div > limits->vt.max_pix_clk_div) {
 361                                 dev_dbg(dev,
 362                                         "pix_div %u too small or too big (%u--%u)\n",
 363                                         pix_div,
 364                                         limits->vt.min_pix_clk_div,
 365                                         limits->vt.max_pix_clk_div);
 366                                 continue;
 367                         }
 368
 369                         /* Check if this one is better. */
 370                         if (pix_div * sys_div
 371                             <= roundup(min_vt_div, best_pix_div))
 372                                 best_pix_div = pix_div;
 373                 }
 374                 if (best_pix_div < INT_MAX >> 1)
 375                         break;
 376         }
 377
 378         pll->vt.sys_clk_div = DIV_ROUND_UP(min_vt_div, best_pix_div);
 379         pll->vt.pix_clk_div = best_pix_div;
 380
 381         pll->vt.sys_clk_freq_hz =
 382                 pll->pll_op_clk_freq_hz / pll->vt.sys_clk_div;
 383         pll->vt.pix_clk_freq_hz =
 384                 pll->vt.sys_clk_freq_hz / pll->vt.pix_clk_div;
 385
 386 out_skip_vt_calc:
 387         pll->pixel_rate_csi =
 388                 op_pll->pix_clk_freq_hz * lane_op_clock_ratio;
 389         pll->pixel_rate_pixel_array = pll->vt.pix_clk_freq_hz;
 390
 391         return check_all_bounds(dev, limits, op_limits, pll, op_pll);
 392 }
 393
 394 int smiapp_pll_calculate(struct device *dev,
 395                          const struct smiapp_pll_limits *limits,
 396                          struct smiapp_pll *pll)
 397 {
 398         const struct smiapp_pll_branch_limits *op_limits = &limits->op;
 399         struct smiapp_pll_branch *op_pll = &pll->op;
 400         uint16_t min_pre_pll_clk_div;
 401         uint16_t max_pre_pll_clk_div;
 402         uint32_t lane_op_clock_ratio;
 403         uint32_t mul, div;
 404         unsigned int i;
 405         int rval = -EINVAL;
 406
 407         if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS) {
 408                 /*
 409                  * If there's no OP PLL at all, use the VT values
 410                  * instead. The OP values are ignored for the rest of
 411                  * the PLL calculation.
 412                  */
 413                 op_limits = &limits->vt;
 414                 op_pll = &pll->vt;
 415         }
 416
 417         if (pll->flags & SMIAPP_PLL_FLAG_OP_PIX_CLOCK_PER_LANE)
 418                 lane_op_clock_ratio = pll->csi2.lanes;
 419         else
 420                 lane_op_clock_ratio = 1;
 421         dev_dbg(dev, "lane_op_clock_ratio: %u\n", lane_op_clock_ratio);
 422
 423         dev_dbg(dev, "binning: %ux%u\n", pll->binning_horizontal,
 424                 pll->binning_vertical);
 425
 426         switch (pll->bus_type) {
 427         case SMIAPP_PLL_BUS_TYPE_CSI2:
 428                 /* CSI transfers 2 bits per clock per lane; thus times 2 */
 429                 pll->pll_op_clk_freq_hz = pll->link_freq * 2
 430                         * (pll->csi2.lanes / lane_op_clock_ratio);
 431                 break;
 432         case SMIAPP_PLL_BUS_TYPE_PARALLEL:
 433                 pll->pll_op_clk_freq_hz = pll->link_freq * pll->bits_per_pixel
 434                         / DIV_ROUND_UP(pll->bits_per_pixel,
 435                                        pll->parallel.bus_width);
 436                 break;
 437         default:
 438                 return -EINVAL;
 439         }
 440
 441         /* Figure out limits for pre-pll divider based on extclk */
 442         dev_dbg(dev, "min / max pre_pll_clk_div: %u / %u\n",
 443                 limits->min_pre_pll_clk_div, limits->max_pre_pll_clk_div);
 444         max_pre_pll_clk_div =
 445                 min_t(uint16_t, limits->max_pre_pll_clk_div,
 446                       clk_div_even(pll->ext_clk_freq_hz /
 447                                    limits->min_pll_ip_freq_hz));
 448         min_pre_pll_clk_div =
 449                 max_t(uint16_t, limits->min_pre_pll_clk_div,
 450                       clk_div_even_up(
 451                               DIV_ROUND_UP(pll->ext_clk_freq_hz,
 452                                            limits->max_pll_ip_freq_hz)));
 453         dev_dbg(dev, "pre-pll check: min / max pre_pll_clk_div: %u / %u\n",
 454                 min_pre_pll_clk_div, max_pre_pll_clk_div);
 455
 456         i = gcd(pll->pll_op_clk_freq_hz, pll->ext_clk_freq_hz);
 457         mul = div_u64(pll->pll_op_clk_freq_hz, i);
 458         div = pll->ext_clk_freq_hz / i;
 459         dev_dbg(dev, "mul %u / div %u\n", mul, div);
 460
 461         min_pre_pll_clk_div =
 462                 max_t(uint16_t, min_pre_pll_clk_div,
 463                       clk_div_even_up(
 464                               DIV_ROUND_UP(mul * pll->ext_clk_freq_hz,
 465                                            limits->max_pll_op_freq_hz)));
 466         dev_dbg(dev, "pll_op check: min / max pre_pll_clk_div: %u / %u\n",
 467                 min_pre_pll_clk_div, max_pre_pll_clk_div);
 468
 469         for (pll->pre_pll_clk_div = min_pre_pll_clk_div;
 470              pll->pre_pll_clk_div <= max_pre_pll_clk_div;
 471              pll->pre_pll_clk_div += 2 - (pll->pre_pll_clk_div & 1)) {
 472                 rval = __smiapp_pll_calculate(dev, limits, op_limits, pll,
 473                                               op_pll, mul, div,
 474                                               lane_op_clock_ratio);
 475                 if (rval)
 476                         continue;
 477
 478                 print_pll(dev, pll);
 479                 return 0;
 480         }
 481
 482         dev_info(dev, "unable to compute pre_pll divisor\n");
 483         return rval;
 484 }
 485 EXPORT_SYMBOL_GPL(smiapp_pll_calculate);
 486
 487 MODULE_AUTHOR("Sakari Ailus <sakari.ailus@iki.fi>");
 488 MODULE_DESCRIPTION("Generic SMIA/SMIA++ PLL calculator");
 489 MODULE_LICENSE("GPL");