arch/arm/mach-tegra/clock.c

   1 /*
   2  *
   3  * Copyright (C) 2010 Google, Inc.
   4  *
   5  * Author:
   6  *      Colin Cross <ccross@google.com>
   7  *
   8  * This software is licensed under the terms of the GNU General Public
   9  * License version 2, as published by the Free Software Foundation, and
  10  * may be copied, distributed, and modified under those terms.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/clk.h>
  21 #include <linux/clkdev.h>
  22 #include <linux/debugfs.h>
  23 #include <linux/delay.h>
  24 #include <linux/init.h>
  25 #include <linux/list.h>
  26 #include <linux/module.h>
  27 #include <linux/sched.h>
  28 #include <linux/seq_file.h>
  29 #include <linux/slab.h>
  30
  31 #include <mach/clk.h>
  32
  33 #include "board.h"
  34 #include "clock.h"
  35
  36 /*
  37  * Locking:
  38  *
  39  * Each struct clk has a spinlock.
  40  *
  41  * To avoid AB-BA locking problems, locks must always be traversed from child
  42  * clock to parent clock.  For example, when enabling a clock, the clock's lock
  43  * is taken, and then clk_enable is called on the parent, which take's the
  44  * parent clock's lock.  There is one exceptions to this ordering: When dumping
  45  * the clock tree through debugfs.  In this case, clk_lock_all is called,
  46  * which attemps to iterate through the entire list of clocks and take every
  47  * clock lock.  If any call to spin_trylock fails, all locked clocks are
  48  * unlocked, and the process is retried.  When all the locks are held,
  49  * the only clock operation that can be called is clk_get_rate_all_locked.
  50  *
  51  * Within a single clock, no clock operation can call another clock operation
  52  * on itself, except for clk_get_rate_locked and clk_set_rate_locked.  Any
  53  * clock operation can call any other clock operation on any of it's possible
  54  * parents.
  55  *
  56  * An additional mutex, clock_list_lock, is used to protect the list of all
  57  * clocks.
  58  *
  59  * The clock operations must lock internally to protect against
  60  * read-modify-write on registers that are shared by multiple clocks
  61  */
  62 static DEFINE_MUTEX(clock_list_lock);
  63 static LIST_HEAD(clocks);
  64
  65 struct clk *tegra_get_clock_by_name(const char *name)
  66 {
  67         struct clk *c;
  68         struct clk *ret = NULL;
  69         mutex_lock(&clock_list_lock);
  70         list_for_each_entry(c, &clocks, node) {
  71                 if (strcmp(c->name, name) == 0) {
  72                         ret = c;
  73                         break;
  74                 }
  75         }
  76         mutex_unlock(&clock_list_lock);
  77         return ret;
  78 }
  79
  80 /* Must be called with c->spinlock held */
  81 static unsigned long clk_predict_rate_from_parent(struct clk *c, struct clk *p)
  82 {
  83         u64 rate;
  84
  85         rate = clk_get_rate(p);
  86
  87         if (c->mul != 0 && c->div != 0) {
  88                 rate *= c->mul;
  89                 rate += c->div - 1; /* round up */
  90                 do_div(rate, c->div);
  91         }
  92
  93         return rate;
  94 }
  95
  96 /* Must be called with c->spinlock held */
  97 unsigned long clk_get_rate_locked(struct clk *c)
  98 {
  99         unsigned long rate;
 100
 101         if (c->parent)
 102                 rate = clk_predict_rate_from_parent(c, c->parent);
 103         else
 104                 rate = c->rate;
 105
 106         return rate;
 107 }
 108
 109 unsigned long clk_get_rate(struct clk *c)
 110 {
 111         unsigned long flags;
 112         unsigned long rate;
 113
 114         spin_lock_irqsave(&c->spinlock, flags);
 115
 116         rate = clk_get_rate_locked(c);
 117
 118         spin_unlock_irqrestore(&c->spinlock, flags);
 119
 120         return rate;
 121 }
 122 EXPORT_SYMBOL(clk_get_rate);
 123
 124 int clk_reparent(struct clk *c, struct clk *parent)
 125 {
 126         c->parent = parent;
 127         return 0;
 128 }
 129
 130 void clk_init(struct clk *c)
 131 {
 132         spin_lock_init(&c->spinlock);
 133
 134         if (c->ops && c->ops->init)
 135                 c->ops->init(c);
 136
 137         if (!c->ops || !c->ops->enable) {
 138                 c->refcnt++;
 139                 c->set = true;
 140                 if (c->parent)
 141                         c->state = c->parent->state;
 142                 else
 143                         c->state = ON;
 144         }
 145
 146         mutex_lock(&clock_list_lock);
 147         list_add(&c->node, &clocks);
 148         mutex_unlock(&clock_list_lock);
 149 }
 150
 151 int clk_enable(struct clk *c)
 152 {
 153         int ret = 0;
 154         unsigned long flags;
 155
 156         spin_lock_irqsave(&c->spinlock, flags);
 157
 158         if (c->refcnt == 0) {
 159                 if (c->parent) {
 160                         ret = clk_enable(c->parent);
 161                         if (ret)
 162                                 goto out;
 163                 }
 164
 165                 if (c->ops && c->ops->enable) {
 166                         ret = c->ops->enable(c);
 167                         if (ret) {
 168                                 if (c->parent)
 169                                         clk_disable(c->parent);
 170                                 goto out;
 171                         }
 172                         c->state = ON;
 173                         c->set = true;
 174                 }
 175         }
 176         c->refcnt++;
 177 out:
 178         spin_unlock_irqrestore(&c->spinlock, flags);
 179         return ret;
 180 }
 181 EXPORT_SYMBOL(clk_enable);
 182
 183 void clk_disable(struct clk *c)
 184 {
 185         unsigned long flags;
 186
 187         spin_lock_irqsave(&c->spinlock, flags);
 188
 189         if (c->refcnt == 0) {
 190                 WARN(1, "Attempting to disable clock %s with refcnt 0", c->name);
 191                 spin_unlock_irqrestore(&c->spinlock, flags);
 192                 return;
 193         }
 194         if (c->refcnt == 1) {
 195                 if (c->ops && c->ops->disable)
 196                         c->ops->disable(c);
 197
 198                 if (c->parent)
 199                         clk_disable(c->parent);
 200
 201                 c->state = OFF;
 202         }
 203         c->refcnt--;
 204
 205         spin_unlock_irqrestore(&c->spinlock, flags);
 206 }
 207 EXPORT_SYMBOL(clk_disable);
 208
 209 int clk_set_parent(struct clk *c, struct clk *parent)
 210 {
 211         int ret;
 212         unsigned long flags;
 213         unsigned long new_rate;
 214         unsigned long old_rate;
 215
 216         spin_lock_irqsave(&c->spinlock, flags);
 217
 218         if (!c->ops || !c->ops->set_parent) {
 219                 ret = -ENOSYS;
 220                 goto out;
 221         }
 222
 223         new_rate = clk_predict_rate_from_parent(c, parent);
 224         old_rate = clk_get_rate_locked(c);
 225
 226         ret = c->ops->set_parent(c, parent);
 227         if (ret)
 228                 goto out;
 229
 230 out:
 231         spin_unlock_irqrestore(&c->spinlock, flags);
 232         return ret;
 233 }
 234 EXPORT_SYMBOL(clk_set_parent);
 235
 236 struct clk *clk_get_parent(struct clk *c)
 237 {
 238         return c->parent;
 239 }
 240 EXPORT_SYMBOL(clk_get_parent);
 241
 242 int clk_set_rate_locked(struct clk *c, unsigned long rate)
 243 {
 244         long new_rate;
 245
 246         if (!c->ops || !c->ops->set_rate)
 247                 return -ENOSYS;
 248
 249         if (rate > c->max_rate)
 250                 rate = c->max_rate;
 251
 252         if (c->ops && c->ops->round_rate) {
 253                 new_rate = c->ops->round_rate(c, rate);
 254
 255                 if (new_rate < 0)
 256                         return new_rate;
 257
 258                 rate = new_rate;
 259         }
 260
 261         return c->ops->set_rate(c, rate);
 262 }
 263
 264 int clk_set_rate(struct clk *c, unsigned long rate)
 265 {
 266         int ret;
 267         unsigned long flags;
 268
 269         spin_lock_irqsave(&c->spinlock, flags);
 270
 271         ret = clk_set_rate_locked(c, rate);
 272
 273         spin_unlock_irqrestore(&c->spinlock, flags);
 274
 275         return ret;
 276 }
 277 EXPORT_SYMBOL(clk_set_rate);
 278
 279
 280 /* Must be called with clocks lock and all indvidual clock locks held */
 281 unsigned long clk_get_rate_all_locked(struct clk *c)
 282 {
 283         u64 rate;
 284         int mul = 1;
 285         int div = 1;
 286         struct clk *p = c;
 287
 288         while (p) {
 289                 c = p;
 290                 if (c->mul != 0 && c->div != 0) {
 291                         mul *= c->mul;
 292                         div *= c->div;
 293                 }
 294                 p = c->parent;
 295         }
 296
 297         rate = c->rate;
 298         rate *= mul;
 299         do_div(rate, div);
 300
 301         return rate;
 302 }
 303
 304 long clk_round_rate(struct clk *c, unsigned long rate)
 305 {
 306         unsigned long flags;
 307         long ret;
 308
 309         spin_lock_irqsave(&c->spinlock, flags);
 310
 311         if (!c->ops || !c->ops->round_rate) {
 312                 ret = -ENOSYS;
 313                 goto out;
 314         }
 315
 316         if (rate > c->max_rate)
 317                 rate = c->max_rate;
 318
 319         ret = c->ops->round_rate(c, rate);
 320
 321 out:
 322         spin_unlock_irqrestore(&c->spinlock, flags);
 323         return ret;
 324 }
 325 EXPORT_SYMBOL(clk_round_rate);
 326
 327 static int tegra_clk_init_one_from_table(struct tegra_clk_init_table *table)
 328 {
 329         struct clk *c;
 330         struct clk *p;
 331
 332         int ret = 0;
 333
 334         c = tegra_get_clock_by_name(table->name);
 335
 336         if (!c) {
 337                 pr_warning("Unable to initialize clock %s\n",
 338                         table->name);
 339                 return -ENODEV;
 340         }
 341
 342         if (table->parent) {
 343                 p = tegra_get_clock_by_name(table->parent);
 344                 if (!p) {
 345                         pr_warning("Unable to find parent %s of clock %s\n",
 346                                 table->parent, table->name);
 347                         return -ENODEV;
 348                 }
 349
 350                 if (c->parent != p) {
 351                         ret = clk_set_parent(c, p);
 352                         if (ret) {
 353                                 pr_warning("Unable to set parent %s of clock %s: %d\n",
 354                                         table->parent, table->name, ret);
 355                                 return -EINVAL;
 356                         }
 357                 }
 358         }
 359
 360         if (table->rate && table->rate != clk_get_rate(c)) {
 361                 ret = clk_set_rate(c, table->rate);
 362                 if (ret) {
 363                         pr_warning("Unable to set clock %s to rate %lu: %d\n",
 364                                 table->name, table->rate, ret);
 365                         return -EINVAL;
 366                 }
 367         }
 368
 369         if (table->enabled) {
 370                 ret = clk_enable(c);
 371                 if (ret) {
 372                         pr_warning("Unable to enable clock %s: %d\n",
 373                                 table->name, ret);
 374                         return -EINVAL;
 375                 }
 376         }
 377
 378         return 0;
 379 }
 380
 381 void tegra_clk_init_from_table(struct tegra_clk_init_table *table)
 382 {
 383         for (; table->name; table++)
 384                 tegra_clk_init_one_from_table(table);
 385 }
 386 EXPORT_SYMBOL(tegra_clk_init_from_table);
 387
 388 void tegra_periph_reset_deassert(struct clk *c)
 389 {
 390         BUG_ON(!c->ops->reset);
 391         c->ops->reset(c, false);
 392 }
 393 EXPORT_SYMBOL(tegra_periph_reset_deassert);
 394
 395 void tegra_periph_reset_assert(struct clk *c)
 396 {
 397         BUG_ON(!c->ops->reset);
 398         c->ops->reset(c, true);
 399 }
 400 EXPORT_SYMBOL(tegra_periph_reset_assert);
 401
 402 #ifdef CONFIG_DEBUG_FS
 403
 404 static int __clk_lock_all_spinlocks(void)
 405 {
 406         struct clk *c;
 407
 408         list_for_each_entry(c, &clocks, node)
 409                 if (!spin_trylock(&c->spinlock))
 410                         goto unlock_spinlocks;
 411
 412         return 0;
 413
 414 unlock_spinlocks:
 415         list_for_each_entry_continue_reverse(c, &clocks, node)
 416                 spin_unlock(&c->spinlock);
 417
 418         return -EAGAIN;
 419 }
 420
 421 static void __clk_unlock_all_spinlocks(void)
 422 {
 423         struct clk *c;
 424
 425         list_for_each_entry_reverse(c, &clocks, node)
 426                 spin_unlock(&c->spinlock);
 427 }
 428
 429 /*
 430  * This function retries until it can take all locks, and may take
 431  * an arbitrarily long time to complete.
 432  * Must be called with irqs enabled, returns with irqs disabled
 433  * Must be called with clock_list_lock held
 434  */
 435 static void clk_lock_all(void)
 436 {
 437         int ret;
 438 retry:
 439         local_irq_disable();
 440
 441         ret = __clk_lock_all_spinlocks();
 442         if (ret)
 443                 goto failed_spinlocks;
 444
 445         /* All locks taken successfully, return */
 446         return;
 447
 448 failed_spinlocks:
 449         local_irq_enable();
 450         yield();
 451         goto retry;
 452 }
 453
 454 /*
 455  * Unlocks all clocks after a clk_lock_all
 456  * Must be called with irqs disabled, returns with irqs enabled
 457  * Must be called with clock_list_lock held
 458  */
 459 static void clk_unlock_all(void)
 460 {
 461         __clk_unlock_all_spinlocks();
 462
 463         local_irq_enable();
 464 }
 465
 466 static struct dentry *clk_debugfs_root;
 467
 468
 469 static void clock_tree_show_one(struct seq_file *s, struct clk *c, int level)
 470 {
 471         struct clk *child;
 472         const char *state = "uninit";
 473         char div[8] = {0};
 474
 475         if (c->state == ON)
 476                 state = "on";
 477         else if (c->state == OFF)
 478                 state = "off";
 479
 480         if (c->mul != 0 && c->div != 0) {
 481                 if (c->mul > c->div) {
 482                         int mul = c->mul / c->div;
 483                         int mul2 = (c->mul * 10 / c->div) % 10;
 484                         int mul3 = (c->mul * 10) % c->div;
 485                         if (mul2 == 0 && mul3 == 0)
 486                                 snprintf(div, sizeof(div), "x%d", mul);
 487                         else if (mul3 == 0)
 488                                 snprintf(div, sizeof(div), "x%d.%d", mul, mul2);
 489                         else
 490                                 snprintf(div, sizeof(div), "x%d.%d..", mul, mul2);
 491                 } else {
 492                         snprintf(div, sizeof(div), "%d%s", c->div / c->mul,
 493                                 (c->div % c->mul) ? ".5" : "");
 494                 }
 495         }
 496
 497         seq_printf(s, "%*s%c%c%-*s %-6s %-3d %-8s %-10lu\n",
 498                 level * 3 + 1, "",
 499                 c->rate > c->max_rate ? '!' : ' ',
 500                 !c->set ? '*' : ' ',
 501                 30 - level * 3, c->name,
 502                 state, c->refcnt, div, clk_get_rate_all_locked(c));
 503
 504         list_for_each_entry(child, &clocks, node) {
 505                 if (child->parent != c)
 506                         continue;
 507
 508                 clock_tree_show_one(s, child, level + 1);
 509         }
 510 }
 511
 512 static int clock_tree_show(struct seq_file *s, void *data)
 513 {
 514         struct clk *c;
 515         seq_printf(s, "   clock                          state  ref div      rate\n");
 516         seq_printf(s, "--------------------------------------------------------------\n");
 517
 518         mutex_lock(&clock_list_lock);
 519
 520         clk_lock_all();
 521
 522         list_for_each_entry(c, &clocks, node)
 523                 if (c->parent == NULL)
 524                         clock_tree_show_one(s, c, 0);
 525
 526         clk_unlock_all();
 527
 528         mutex_unlock(&clock_list_lock);
 529         return 0;
 530 }
 531
 532 static int clock_tree_open(struct inode *inode, struct file *file)
 533 {
 534         return single_open(file, clock_tree_show, inode->i_private);
 535 }
 536
 537 static const struct file_operations clock_tree_fops = {
 538         .open           = clock_tree_open,
 539         .read           = seq_read,
 540         .llseek         = seq_lseek,
 541         .release        = single_release,
 542 };
 543
 544 static int possible_parents_show(struct seq_file *s, void *data)
 545 {
 546         struct clk *c = s->private;
 547         int i;
 548
 549         for (i = 0; c->inputs[i].input; i++) {
 550                 char *first = (i == 0) ? "" : " ";
 551                 seq_printf(s, "%s%s", first, c->inputs[i].input->name);
 552         }
 553         seq_printf(s, "\n");
 554         return 0;
 555 }
 556
 557 static int possible_parents_open(struct inode *inode, struct file *file)
 558 {
 559         return single_open(file, possible_parents_show, inode->i_private);
 560 }
 561
 562 static const struct file_operations possible_parents_fops = {
 563         .open           = possible_parents_open,
 564         .read           = seq_read,
 565         .llseek         = seq_lseek,
 566         .release        = single_release,
 567 };
 568
 569 static int clk_debugfs_register_one(struct clk *c)
 570 {
 571         struct dentry *d;
 572
 573         d = debugfs_create_dir(c->name, clk_debugfs_root);
 574         if (!d)
 575                 return -ENOMEM;
 576         c->dent = d;
 577
 578         d = debugfs_create_u8("refcnt", S_IRUGO, c->dent, (u8 *)&c->refcnt);
 579         if (!d)
 580                 goto err_out;
 581
 582         d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
 583         if (!d)
 584                 goto err_out;
 585
 586         d = debugfs_create_x32("flags", S_IRUGO, c->dent, (u32 *)&c->flags);
 587         if (!d)
 588                 goto err_out;
 589
 590         if (c->inputs) {
 591                 d = debugfs_create_file("possible_parents", S_IRUGO, c->dent,
 592                         c, &possible_parents_fops);
 593                 if (!d)
 594                         goto err_out;
 595         }
 596
 597         return 0;
 598
 599 err_out:
 600         debugfs_remove_recursive(c->dent);
 601         return -ENOMEM;
 602 }
 603
 604 static int clk_debugfs_register(struct clk *c)
 605 {
 606         int err;
 607         struct clk *pa = c->parent;
 608
 609         if (pa && !pa->dent) {
 610                 err = clk_debugfs_register(pa);
 611                 if (err)
 612                         return err;
 613         }
 614
 615         if (!c->dent) {
 616                 err = clk_debugfs_register_one(c);
 617                 if (err)
 618                         return err;
 619         }
 620         return 0;
 621 }
 622
 623 static int __init clk_debugfs_init(void)
 624 {
 625         struct clk *c;
 626         struct dentry *d;
 627         int err = -ENOMEM;
 628
 629         d = debugfs_create_dir("clock", NULL);
 630         if (!d)
 631                 return -ENOMEM;
 632         clk_debugfs_root = d;
 633
 634         d = debugfs_create_file("clock_tree", S_IRUGO, clk_debugfs_root, NULL,
 635                 &clock_tree_fops);
 636         if (!d)
 637                 goto err_out;
 638
 639         list_for_each_entry(c, &clocks, node) {
 640                 err = clk_debugfs_register(c);
 641                 if (err)
 642                         goto err_out;
 643         }
 644         return 0;
 645 err_out:
 646         debugfs_remove_recursive(clk_debugfs_root);
 647         return err;
 648 }
 649
 650 late_initcall(clk_debugfs_init);
 651 #endif