drivers/clk/clk-divider.c

   1 /*
   2  * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
   3  * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
   4  * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Adjustable divider clock implementation
  11  */
  12
  13 #include <linux/clk-provider.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/io.h>
  17 #include <linux/err.h>
  18 #include <linux/string.h>
  19 #include <linux/log2.h>
  20
  21 /*
  22  * DOC: basic adjustable divider clock that cannot gate
  23  *
  24  * Traits of this clock:
  25  * prepare - clk_prepare only ensures that parents are prepared
  26  * enable - clk_enable only ensures that parents are enabled
  27  * rate - rate is adjustable.  clk->rate = ceiling(parent->rate / divisor)
  28  * parent - fixed parent.  No clk_set_parent support
  29  */
  30
  31 #define div_mask(width) ((1 << (width)) - 1)
  32
  33 static unsigned int _get_table_maxdiv(const struct clk_div_table *table,
  34                                       u8 width)
  35 {
  36         unsigned int maxdiv = 0, mask = div_mask(width);
  37         const struct clk_div_table *clkt;
  38
  39         for (clkt = table; clkt->div; clkt++)
  40                 if (clkt->div > maxdiv && clkt->val <= mask)
  41                         maxdiv = clkt->div;
  42         return maxdiv;
  43 }
  44
  45 static unsigned int _get_table_mindiv(const struct clk_div_table *table)
  46 {
  47         unsigned int mindiv = UINT_MAX;
  48         const struct clk_div_table *clkt;
  49
  50         for (clkt = table; clkt->div; clkt++)
  51                 if (clkt->div < mindiv)
  52                         mindiv = clkt->div;
  53         return mindiv;
  54 }
  55
  56 static unsigned int _get_maxdiv(const struct clk_div_table *table, u8 width,
  57                                 unsigned long flags)
  58 {
  59         if (flags & CLK_DIVIDER_ONE_BASED)
  60                 return div_mask(width);
  61         if (flags & CLK_DIVIDER_POWER_OF_TWO)
  62                 return 1 << div_mask(width);
  63         if (table)
  64                 return _get_table_maxdiv(table, width);
  65         return div_mask(width) + 1;
  66 }
  67
  68 static unsigned int _get_table_div(const struct clk_div_table *table,
  69                                                         unsigned int val)
  70 {
  71         const struct clk_div_table *clkt;
  72
  73         for (clkt = table; clkt->div; clkt++)
  74                 if (clkt->val == val)
  75                         return clkt->div;
  76         return 0;
  77 }
  78
  79 static unsigned int _get_div(const struct clk_div_table *table,
  80                              unsigned int val, unsigned long flags, u8 width)
  81 {
  82         if (flags & CLK_DIVIDER_ONE_BASED)
  83                 return val;
  84         if (flags & CLK_DIVIDER_POWER_OF_TWO)
  85                 return 1 << val;
  86         if (flags & CLK_DIVIDER_MAX_AT_ZERO)
  87                 return val ? val : div_mask(width) + 1;
  88         if (table)
  89                 return _get_table_div(table, val);
  90         return val + 1;
  91 }
  92
  93 static unsigned int _get_table_val(const struct clk_div_table *table,
  94                                                         unsigned int div)
  95 {
  96         const struct clk_div_table *clkt;
  97
  98         for (clkt = table; clkt->div; clkt++)
  99                 if (clkt->div == div)
 100                         return clkt->val;
 101         return 0;
 102 }
 103
 104 static unsigned int _get_val(const struct clk_div_table *table,
 105                              unsigned int div, unsigned long flags, u8 width)
 106 {
 107         if (flags & CLK_DIVIDER_ONE_BASED)
 108                 return div;
 109         if (flags & CLK_DIVIDER_POWER_OF_TWO)
 110                 return __ffs(div);
 111         if (flags & CLK_DIVIDER_MAX_AT_ZERO)
 112                 return (div == div_mask(width) + 1) ? 0 : div;
 113         if (table)
 114                 return  _get_table_val(table, div);
 115         return div - 1;
 116 }
 117
 118 unsigned long divider_recalc_rate(struct clk_hw *hw, unsigned long parent_rate,
 119                                   unsigned int val,
 120                                   const struct clk_div_table *table,
 121                                   unsigned long flags)
 122 {
 123         struct clk_divider *divider = to_clk_divider(hw);
 124         unsigned int div;
 125
 126         div = _get_div(table, val, flags, divider->width);
 127         if (!div) {
 128                 WARN(!(flags & CLK_DIVIDER_ALLOW_ZERO),
 129                         "%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
 130                         clk_hw_get_name(hw));
 131                 return parent_rate;
 132         }
 133
 134         return DIV_ROUND_UP_ULL((u64)parent_rate, div);
 135 }
 136 EXPORT_SYMBOL_GPL(divider_recalc_rate);
 137
 138 static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
 139                 unsigned long parent_rate)
 140 {
 141         struct clk_divider *divider = to_clk_divider(hw);
 142         unsigned int val;
 143
 144         val = clk_readl(divider->reg) >> divider->shift;
 145         val &= div_mask(divider->width);
 146
 147         return divider_recalc_rate(hw, parent_rate, val, divider->table,
 148                                    divider->flags);
 149 }
 150
 151 static bool _is_valid_table_div(const struct clk_div_table *table,
 152                                                          unsigned int div)
 153 {
 154         const struct clk_div_table *clkt;
 155
 156         for (clkt = table; clkt->div; clkt++)
 157                 if (clkt->div == div)
 158                         return true;
 159         return false;
 160 }
 161
 162 static bool _is_valid_div(const struct clk_div_table *table, unsigned int div,
 163                           unsigned long flags)
 164 {
 165         if (flags & CLK_DIVIDER_POWER_OF_TWO)
 166                 return is_power_of_2(div);
 167         if (table)
 168                 return _is_valid_table_div(table, div);
 169         return true;
 170 }
 171
 172 static int _round_up_table(const struct clk_div_table *table, int div)
 173 {
 174         const struct clk_div_table *clkt;
 175         int up = INT_MAX;
 176
 177         for (clkt = table; clkt->div; clkt++) {
 178                 if (clkt->div == div)
 179                         return clkt->div;
 180                 else if (clkt->div < div)
 181                         continue;
 182
 183                 if ((clkt->div - div) < (up - div))
 184                         up = clkt->div;
 185         }
 186
 187         return up;
 188 }
 189
 190 static int _round_down_table(const struct clk_div_table *table, int div)
 191 {
 192         const struct clk_div_table *clkt;
 193         int down = _get_table_mindiv(table);
 194
 195         for (clkt = table; clkt->div; clkt++) {
 196                 if (clkt->div == div)
 197                         return clkt->div;
 198                 else if (clkt->div > div)
 199                         continue;
 200
 201                 if ((div - clkt->div) < (div - down))
 202                         down = clkt->div;
 203         }
 204
 205         return down;
 206 }
 207
 208 static int _div_round_up(const struct clk_div_table *table,
 209                          unsigned long parent_rate, unsigned long rate,
 210                          unsigned long flags)
 211 {
 212         int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
 213
 214         if (flags & CLK_DIVIDER_POWER_OF_TWO)
 215                 div = __roundup_pow_of_two(div);
 216         if (table)
 217                 div = _round_up_table(table, div);
 218
 219         return div;
 220 }
 221
 222 static int _div_round_closest(const struct clk_div_table *table,
 223                               unsigned long parent_rate, unsigned long rate,
 224                               unsigned long flags)
 225 {
 226         int up, down;
 227         unsigned long up_rate, down_rate;
 228
 229         up = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
 230         down = parent_rate / rate;
 231
 232         if (flags & CLK_DIVIDER_POWER_OF_TWO) {
 233                 up = __roundup_pow_of_two(up);
 234                 down = __rounddown_pow_of_two(down);
 235         } else if (table) {
 236                 up = _round_up_table(table, up);
 237                 down = _round_down_table(table, down);
 238         }
 239
 240         up_rate = DIV_ROUND_UP_ULL((u64)parent_rate, up);
 241         down_rate = DIV_ROUND_UP_ULL((u64)parent_rate, down);
 242
 243         return (rate - up_rate) <= (down_rate - rate) ? up : down;
 244 }
 245
 246 static int _div_round(const struct clk_div_table *table,
 247                       unsigned long parent_rate, unsigned long rate,
 248                       unsigned long flags)
 249 {
 250         if (flags & CLK_DIVIDER_ROUND_CLOSEST)
 251                 return _div_round_closest(table, parent_rate, rate, flags);
 252
 253         return _div_round_up(table, parent_rate, rate, flags);
 254 }
 255
 256 static bool _is_best_div(unsigned long rate, unsigned long now,
 257                          unsigned long best, unsigned long flags)
 258 {
 259         if (flags & CLK_DIVIDER_ROUND_CLOSEST)
 260                 return abs(rate - now) < abs(rate - best);
 261
 262         return now <= rate && now > best;
 263 }
 264
 265 static int _next_div(const struct clk_div_table *table, int div,
 266                      unsigned long flags)
 267 {
 268         div++;
 269
 270         if (flags & CLK_DIVIDER_POWER_OF_TWO)
 271                 return __roundup_pow_of_two(div);
 272         if (table)
 273                 return _round_up_table(table, div);
 274
 275         return div;
 276 }
 277
 278 static int clk_divider_bestdiv(struct clk_hw *hw, struct clk_hw *parent,
 279                                unsigned long rate,
 280                                unsigned long *best_parent_rate,
 281                                const struct clk_div_table *table, u8 width,
 282                                unsigned long flags)
 283 {
 284         int i, bestdiv = 0;
 285         unsigned long parent_rate, best = 0, now, maxdiv;
 286         unsigned long parent_rate_saved = *best_parent_rate;
 287
 288         if (!rate)
 289                 rate = 1;
 290
 291         maxdiv = _get_maxdiv(table, width, flags);
 292
 293         if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
 294                 parent_rate = *best_parent_rate;
 295                 bestdiv = _div_round(table, parent_rate, rate, flags);
 296                 bestdiv = bestdiv == 0 ? 1 : bestdiv;
 297                 bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
 298                 return bestdiv;
 299         }
 300
 301         /*
 302          * The maximum divider we can use without overflowing
 303          * unsigned long in rate * i below
 304          */
 305         maxdiv = min(ULONG_MAX / rate, maxdiv);
 306
 307         for (i = _next_div(table, 0, flags); i <= maxdiv;
 308                                              i = _next_div(table, i, flags)) {
 309                 if (rate * i == parent_rate_saved) {
 310                         /*
 311                          * It's the most ideal case if the requested rate can be
 312                          * divided from parent clock without needing to change
 313                          * parent rate, so return the divider immediately.
 314                          */
 315                         *best_parent_rate = parent_rate_saved;
 316                         return i;
 317                 }
 318                 parent_rate = clk_hw_round_rate(parent, rate * i);
 319                 now = DIV_ROUND_UP_ULL((u64)parent_rate, i);
 320                 if (_is_best_div(rate, now, best, flags)) {
 321                         bestdiv = i;
 322                         best = now;
 323                         *best_parent_rate = parent_rate;
 324                 }
 325         }
 326
 327         if (!bestdiv) {
 328                 bestdiv = _get_maxdiv(table, width, flags);
 329                 *best_parent_rate = clk_hw_round_rate(parent, 1);
 330         }
 331
 332         return bestdiv;
 333 }
 334
 335 long divider_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
 336                                unsigned long rate, unsigned long *prate,
 337                                const struct clk_div_table *table,
 338                                u8 width, unsigned long flags)
 339 {
 340         int div;
 341
 342         div = clk_divider_bestdiv(hw, parent, rate, prate, table, width, flags);
 343
 344         return DIV_ROUND_UP_ULL((u64)*prate, div);
 345 }
 346 EXPORT_SYMBOL_GPL(divider_round_rate_parent);
 347
 348 static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
 349                                 unsigned long *prate)
 350 {
 351         struct clk_divider *divider = to_clk_divider(hw);
 352         int bestdiv;
 353
 354         /* if read only, just return current value */
 355         if (divider->flags & CLK_DIVIDER_READ_ONLY) {
 356                 bestdiv = clk_readl(divider->reg) >> divider->shift;
 357                 bestdiv &= div_mask(divider->width);
 358                 bestdiv = _get_div(divider->table, bestdiv, divider->flags,
 359                         divider->width);
 360                 return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
 361         }
 362
 363         return divider_round_rate(hw, rate, prate, divider->table,
 364                                   divider->width, divider->flags);
 365 }
 366
 367 int divider_get_val(unsigned long rate, unsigned long parent_rate,
 368                     const struct clk_div_table *table, u8 width,
 369                     unsigned long flags)
 370 {
 371         unsigned int div, value;
 372
 373         div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
 374
 375         if (!_is_valid_div(table, div, flags))
 376                 return -EINVAL;
 377
 378         value = _get_val(table, div, flags, width);
 379
 380         return min_t(unsigned int, value, div_mask(width));
 381 }
 382 EXPORT_SYMBOL_GPL(divider_get_val);
 383
 384 static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
 385                                 unsigned long parent_rate)
 386 {
 387         struct clk_divider *divider = to_clk_divider(hw);
 388         int value;
 389         unsigned long flags = 0;
 390         u32 val;
 391
 392         value = divider_get_val(rate, parent_rate, divider->table,
 393                                 divider->width, divider->flags);
 394         if (value < 0)
 395                 return value;
 396
 397         if (divider->lock)
 398                 spin_lock_irqsave(divider->lock, flags);
 399         else
 400                 __acquire(divider->lock);
 401
 402         if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
 403                 val = div_mask(divider->width) << (divider->shift + 16);
 404         } else {
 405                 val = clk_readl(divider->reg);
 406                 val &= ~(div_mask(divider->width) << divider->shift);
 407         }
 408         val |= (u32)value << divider->shift;
 409         clk_writel(val, divider->reg);
 410
 411         if (divider->lock)
 412                 spin_unlock_irqrestore(divider->lock, flags);
 413         else
 414                 __release(divider->lock);
 415
 416         return 0;
 417 }
 418
 419 const struct clk_ops clk_divider_ops = {
 420         .recalc_rate = clk_divider_recalc_rate,
 421         .round_rate = clk_divider_round_rate,
 422         .set_rate = clk_divider_set_rate,
 423 };
 424 EXPORT_SYMBOL_GPL(clk_divider_ops);
 425
 426 const struct clk_ops clk_divider_ro_ops = {
 427         .recalc_rate = clk_divider_recalc_rate,
 428         .round_rate = clk_divider_round_rate,
 429 };
 430 EXPORT_SYMBOL_GPL(clk_divider_ro_ops);
 431
 432 static struct clk_hw *_register_divider(struct device *dev, const char *name,
 433                 const char *parent_name, unsigned long flags,
 434                 void __iomem *reg, u8 shift, u8 width,
 435                 u8 clk_divider_flags, const struct clk_div_table *table,
 436                 spinlock_t *lock)
 437 {
 438         struct clk_divider *div;
 439         struct clk_hw *hw;
 440         struct clk_init_data init;
 441         int ret;
 442
 443         if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
 444                 if (width + shift > 16) {
 445                         pr_warn("divider value exceeds LOWORD field\n");
 446                         return ERR_PTR(-EINVAL);
 447                 }
 448         }
 449
 450         /* allocate the divider */
 451         div = kzalloc(sizeof(*div), GFP_KERNEL);
 452         if (!div)
 453                 return ERR_PTR(-ENOMEM);
 454
 455         init.name = name;
 456         if (clk_divider_flags & CLK_DIVIDER_READ_ONLY)
 457                 init.ops = &clk_divider_ro_ops;
 458         else
 459                 init.ops = &clk_divider_ops;
 460         init.flags = flags | CLK_IS_BASIC;
 461         init.parent_names = (parent_name ? &parent_name: NULL);
 462         init.num_parents = (parent_name ? 1 : 0);
 463
 464         /* struct clk_divider assignments */
 465         div->reg = reg;
 466         div->shift = shift;
 467         div->width = width;
 468         div->flags = clk_divider_flags;
 469         div->lock = lock;
 470         div->hw.init = &init;
 471         div->table = table;
 472
 473         /* register the clock */
 474         hw = &div->hw;
 475         ret = clk_hw_register(dev, hw);
 476         if (ret) {
 477                 kfree(div);
 478                 hw = ERR_PTR(ret);
 479         }
 480
 481         return hw;
 482 }
 483
 484 /**
 485  * clk_register_divider - register a divider clock with the clock framework
 486  * @dev: device registering this clock
 487  * @name: name of this clock
 488  * @parent_name: name of clock's parent
 489  * @flags: framework-specific flags
 490  * @reg: register address to adjust divider
 491  * @shift: number of bits to shift the bitfield
 492  * @width: width of the bitfield
 493  * @clk_divider_flags: divider-specific flags for this clock
 494  * @lock: shared register lock for this clock
 495  */
 496 struct clk *clk_register_divider(struct device *dev, const char *name,
 497                 const char *parent_name, unsigned long flags,
 498                 void __iomem *reg, u8 shift, u8 width,
 499                 u8 clk_divider_flags, spinlock_t *lock)
 500 {
 501         struct clk_hw *hw;
 502
 503         hw =  _register_divider(dev, name, parent_name, flags, reg, shift,
 504                         width, clk_divider_flags, NULL, lock);
 505         if (IS_ERR(hw))
 506                 return ERR_CAST(hw);
 507         return hw->clk;
 508 }
 509 EXPORT_SYMBOL_GPL(clk_register_divider);
 510
 511 /**
 512  * clk_hw_register_divider - register a divider clock with the clock framework
 513  * @dev: device registering this clock
 514  * @name: name of this clock
 515  * @parent_name: name of clock's parent
 516  * @flags: framework-specific flags
 517  * @reg: register address to adjust divider
 518  * @shift: number of bits to shift the bitfield
 519  * @width: width of the bitfield
 520  * @clk_divider_flags: divider-specific flags for this clock
 521  * @lock: shared register lock for this clock
 522  */
 523 struct clk_hw *clk_hw_register_divider(struct device *dev, const char *name,
 524                 const char *parent_name, unsigned long flags,
 525                 void __iomem *reg, u8 shift, u8 width,
 526                 u8 clk_divider_flags, spinlock_t *lock)
 527 {
 528         return _register_divider(dev, name, parent_name, flags, reg, shift,
 529                         width, clk_divider_flags, NULL, lock);
 530 }
 531 EXPORT_SYMBOL_GPL(clk_hw_register_divider);
 532
 533 /**
 534  * clk_register_divider_table - register a table based divider clock with
 535  * the clock framework
 536  * @dev: device registering this clock
 537  * @name: name of this clock
 538  * @parent_name: name of clock's parent
 539  * @flags: framework-specific flags
 540  * @reg: register address to adjust divider
 541  * @shift: number of bits to shift the bitfield
 542  * @width: width of the bitfield
 543  * @clk_divider_flags: divider-specific flags for this clock
 544  * @table: array of divider/value pairs ending with a div set to 0
 545  * @lock: shared register lock for this clock
 546  */
 547 struct clk *clk_register_divider_table(struct device *dev, const char *name,
 548                 const char *parent_name, unsigned long flags,
 549                 void __iomem *reg, u8 shift, u8 width,
 550                 u8 clk_divider_flags, const struct clk_div_table *table,
 551                 spinlock_t *lock)
 552 {
 553         struct clk_hw *hw;
 554
 555         hw =  _register_divider(dev, name, parent_name, flags, reg, shift,
 556                         width, clk_divider_flags, table, lock);
 557         if (IS_ERR(hw))
 558                 return ERR_CAST(hw);
 559         return hw->clk;
 560 }
 561 EXPORT_SYMBOL_GPL(clk_register_divider_table);
 562
 563 /**
 564  * clk_hw_register_divider_table - register a table based divider clock with
 565  * the clock framework
 566  * @dev: device registering this clock
 567  * @name: name of this clock
 568  * @parent_name: name of clock's parent
 569  * @flags: framework-specific flags
 570  * @reg: register address to adjust divider
 571  * @shift: number of bits to shift the bitfield
 572  * @width: width of the bitfield
 573  * @clk_divider_flags: divider-specific flags for this clock
 574  * @table: array of divider/value pairs ending with a div set to 0
 575  * @lock: shared register lock for this clock
 576  */
 577 struct clk_hw *clk_hw_register_divider_table(struct device *dev,
 578                 const char *name, const char *parent_name, unsigned long flags,
 579                 void __iomem *reg, u8 shift, u8 width,
 580                 u8 clk_divider_flags, const struct clk_div_table *table,
 581                 spinlock_t *lock)
 582 {
 583         return _register_divider(dev, name, parent_name, flags, reg, shift,
 584                         width, clk_divider_flags, table, lock);
 585 }
 586 EXPORT_SYMBOL_GPL(clk_hw_register_divider_table);
 587
 588 void clk_unregister_divider(struct clk *clk)
 589 {
 590         struct clk_divider *div;
 591         struct clk_hw *hw;
 592
 593         hw = __clk_get_hw(clk);
 594         if (!hw)
 595                 return;
 596
 597         div = to_clk_divider(hw);
 598
 599         clk_unregister(clk);
 600         kfree(div);
 601 }
 602 EXPORT_SYMBOL_GPL(clk_unregister_divider);
 603
 604 /**
 605  * clk_hw_unregister_divider - unregister a clk divider
 606  * @hw: hardware-specific clock data to unregister
 607  */
 608 void clk_hw_unregister_divider(struct clk_hw *hw)
 609 {
 610         struct clk_divider *div;
 611
 612         div = to_clk_divider(hw);
 613
 614         clk_hw_unregister(hw);
 615         kfree(div);
 616 }
 617 EXPORT_SYMBOL_GPL(clk_hw_unregister_divider);