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                 do_div(rate, c->div);
  90         }
  91
  92         return rate;
  93 }
  94
  95 /* Must be called with c->spinlock held */
  96 unsigned long clk_get_rate_locked(struct clk *c)
  97 {
  98         unsigned long rate;
  99
 100         if (c->parent)
 101                 rate = clk_predict_rate_from_parent(c, c->parent);
 102         else
 103                 rate = c->rate;
 104
 105         return rate;
 106 }
 107
 108 unsigned long clk_get_rate(struct clk *c)
 109 {
 110         unsigned long flags;
 111         unsigned long rate;
 112
 113         spin_lock_irqsave(&c->spinlock, flags);
 114
 115         rate = clk_get_rate_locked(c);
 116
 117         spin_unlock_irqrestore(&c->spinlock, flags);
 118
 119         return rate;
 120 }
 121 EXPORT_SYMBOL(clk_get_rate);
 122
 123 int clk_reparent(struct clk *c, struct clk *parent)
 124 {
 125         c->parent = parent;
 126         return 0;
 127 }
 128
 129 void clk_init(struct clk *c)
 130 {
 131         spin_lock_init(&c->spinlock);
 132
 133         if (c->ops && c->ops->init)
 134                 c->ops->init(c);
 135
 136         if (!c->ops || !c->ops->enable) {
 137                 c->refcnt++;
 138                 c->set = true;
 139                 if (c->parent)
 140                         c->state = c->parent->state;
 141                 else
 142                         c->state = ON;
 143         }
 144
 145         mutex_lock(&clock_list_lock);
 146         list_add(&c->node, &clocks);
 147         mutex_unlock(&clock_list_lock);
 148 }
 149
 150 int clk_enable(struct clk *c)
 151 {
 152         int ret = 0;
 153         unsigned long flags;
 154
 155         spin_lock_irqsave(&c->spinlock, flags);
 156
 157         if (c->refcnt == 0) {
 158                 if (c->parent) {
 159                         ret = clk_enable(c->parent);
 160                         if (ret)
 161                                 goto out;
 162                 }
 163
 164                 if (c->ops && c->ops->enable) {
 165                         ret = c->ops->enable(c);
 166                         if (ret) {
 167                                 if (c->parent)
 168                                         clk_disable(c->parent);
 169                                 goto out;
 170                         }
 171                         c->state = ON;
 172                         c->set = true;
 173                 }
 174         }
 175         c->refcnt++;
 176 out:
 177         spin_unlock_irqrestore(&c->spinlock, flags);
 178         return ret;
 179 }
 180 EXPORT_SYMBOL(clk_enable);
 181
 182 void clk_disable(struct clk *c)
 183 {
 184         unsigned long flags;
 185
 186         spin_lock_irqsave(&c->spinlock, flags);
 187
 188         if (c->refcnt == 0) {
 189                 WARN(1, "Attempting to disable clock %s with refcnt 0", c->name);
 190                 spin_unlock_irqrestore(&c->spinlock, flags);
 191                 return;
 192         }
 193         if (c->refcnt == 1) {
 194                 if (c->ops && c->ops->disable)
 195                         c->ops->disable(c);
 196
 197                 if (c->parent)
 198                         clk_disable(c->parent);
 199
 200                 c->state = OFF;
 201         }
 202         c->refcnt--;
 203
 204         spin_unlock_irqrestore(&c->spinlock, flags);
 205 }
 206 EXPORT_SYMBOL(clk_disable);
 207
 208 int clk_set_parent(struct clk *c, struct clk *parent)
 209 {
 210         int ret;
 211         unsigned long flags;
 212         unsigned long new_rate;
 213         unsigned long old_rate;
 214
 215         spin_lock_irqsave(&c->spinlock, flags);
 216
 217         if (!c->ops || !c->ops->set_parent) {
 218                 ret = -ENOSYS;
 219                 goto out;
 220         }
 221
 222         new_rate = clk_predict_rate_from_parent(c, parent);
 223         old_rate = clk_get_rate_locked(c);
 224
 225         ret = c->ops->set_parent(c, parent);
 226         if (ret)
 227                 goto out;
 228
 229 out:
 230         spin_unlock_irqrestore(&c->spinlock, flags);
 231         return ret;
 232 }
 233 EXPORT_SYMBOL(clk_set_parent);
 234
 235 struct clk *clk_get_parent(struct clk *c)
 236 {
 237         return c->parent;
 238 }
 239 EXPORT_SYMBOL(clk_get_parent);
 240
 241 int clk_set_rate_locked(struct clk *c, unsigned long rate)
 242 {
 243         if (!c->ops || !c->ops->set_rate)
 244                 return -ENOSYS;
 245
 246         if (rate > c->max_rate)
 247                 rate = c->max_rate;
 248
 249         return c->ops->set_rate(c, rate);
 250 }
 251
 252 int clk_set_rate(struct clk *c, unsigned long rate)
 253 {
 254         int ret;
 255         unsigned long flags;
 256
 257         spin_lock_irqsave(&c->spinlock, flags);
 258
 259         ret = clk_set_rate_locked(c, rate);
 260
 261         spin_unlock_irqrestore(&c->spinlock, flags);
 262
 263         return ret;
 264 }
 265 EXPORT_SYMBOL(clk_set_rate);
 266
 267
 268 /* Must be called with clocks lock and all indvidual clock locks held */
 269 unsigned long clk_get_rate_all_locked(struct clk *c)
 270 {
 271         u64 rate;
 272         int mul = 1;
 273         int div = 1;
 274         struct clk *p = c;
 275
 276         while (p) {
 277                 c = p;
 278                 if (c->mul != 0 && c->div != 0) {
 279                         mul *= c->mul;
 280                         div *= c->div;
 281                 }
 282                 p = c->parent;
 283         }
 284
 285         rate = c->rate;
 286         rate *= mul;
 287         do_div(rate, div);
 288
 289         return rate;
 290 }
 291
 292 long clk_round_rate(struct clk *c, unsigned long rate)
 293 {
 294         unsigned long flags;
 295         long ret;
 296
 297         spin_lock_irqsave(&c->spinlock, flags);
 298
 299         if (!c->ops || !c->ops->round_rate) {
 300                 ret = -ENOSYS;
 301                 goto out;
 302         }
 303
 304         if (rate > c->max_rate)
 305                 rate = c->max_rate;
 306
 307         ret = c->ops->round_rate(c, rate);
 308
 309 out:
 310         spin_unlock_irqrestore(&c->spinlock, flags);
 311         return ret;
 312 }
 313 EXPORT_SYMBOL(clk_round_rate);
 314
 315 static int tegra_clk_init_one_from_table(struct tegra_clk_init_table *table)
 316 {
 317         struct clk *c;
 318         struct clk *p;
 319
 320         int ret = 0;
 321
 322         c = tegra_get_clock_by_name(table->name);
 323
 324         if (!c) {
 325                 pr_warning("Unable to initialize clock %s\n",
 326                         table->name);
 327                 return -ENODEV;
 328         }
 329
 330         if (table->parent) {
 331                 p = tegra_get_clock_by_name(table->parent);
 332                 if (!p) {
 333                         pr_warning("Unable to find parent %s of clock %s\n",
 334                                 table->parent, table->name);
 335                         return -ENODEV;
 336                 }
 337
 338                 if (c->parent != p) {
 339                         ret = clk_set_parent(c, p);
 340                         if (ret) {
 341                                 pr_warning("Unable to set parent %s of clock %s: %d\n",
 342                                         table->parent, table->name, ret);
 343                                 return -EINVAL;
 344                         }
 345                 }
 346         }
 347
 348         if (table->rate && table->rate != clk_get_rate(c)) {
 349                 ret = clk_set_rate(c, table->rate);
 350                 if (ret) {
 351                         pr_warning("Unable to set clock %s to rate %lu: %d\n",
 352                                 table->name, table->rate, ret);
 353                         return -EINVAL;
 354                 }
 355         }
 356
 357         if (table->enabled) {
 358                 ret = clk_enable(c);
 359                 if (ret) {
 360                         pr_warning("Unable to enable clock %s: %d\n",
 361                                 table->name, ret);
 362                         return -EINVAL;
 363                 }
 364         }
 365
 366         return 0;
 367 }
 368
 369 void tegra_clk_init_from_table(struct tegra_clk_init_table *table)
 370 {
 371         for (; table->name; table++)
 372                 tegra_clk_init_one_from_table(table);
 373 }
 374 EXPORT_SYMBOL(tegra_clk_init_from_table);
 375
 376 void tegra_periph_reset_deassert(struct clk *c)
 377 {
 378         tegra2_periph_reset_deassert(c);
 379 }
 380 EXPORT_SYMBOL(tegra_periph_reset_deassert);
 381
 382 void tegra_periph_reset_assert(struct clk *c)
 383 {
 384         tegra2_periph_reset_assert(c);
 385 }
 386 EXPORT_SYMBOL(tegra_periph_reset_assert);
 387
 388 void __init tegra_init_clock(void)
 389 {
 390         tegra2_init_clocks();
 391 }
 392
 393 #ifdef CONFIG_DEBUG_FS
 394
 395 static int __clk_lock_all_spinlocks(void)
 396 {
 397         struct clk *c;
 398
 399         list_for_each_entry(c, &clocks, node)
 400                 if (!spin_trylock(&c->spinlock))
 401                         goto unlock_spinlocks;
 402
 403         return 0;
 404
 405 unlock_spinlocks:
 406         list_for_each_entry_continue_reverse(c, &clocks, node)
 407                 spin_unlock(&c->spinlock);
 408
 409         return -EAGAIN;
 410 }
 411
 412 static void __clk_unlock_all_spinlocks(void)
 413 {
 414         struct clk *c;
 415
 416         list_for_each_entry_reverse(c, &clocks, node)
 417                 spin_unlock(&c->spinlock);
 418 }
 419
 420 /*
 421  * This function retries until it can take all locks, and may take
 422  * an arbitrarily long time to complete.
 423  * Must be called with irqs enabled, returns with irqs disabled
 424  * Must be called with clock_list_lock held
 425  */
 426 static void clk_lock_all(void)
 427 {
 428         int ret;
 429 retry:
 430         local_irq_disable();
 431
 432         ret = __clk_lock_all_spinlocks();
 433         if (ret)
 434                 goto failed_spinlocks;
 435
 436         /* All locks taken successfully, return */
 437         return;
 438
 439 failed_spinlocks:
 440         local_irq_enable();
 441         yield();
 442         goto retry;
 443 }
 444
 445 /*
 446  * Unlocks all clocks after a clk_lock_all
 447  * Must be called with irqs disabled, returns with irqs enabled
 448  * Must be called with clock_list_lock held
 449  */
 450 static void clk_unlock_all(void)
 451 {
 452         __clk_unlock_all_spinlocks();
 453
 454         local_irq_enable();
 455 }
 456
 457 static struct dentry *clk_debugfs_root;
 458
 459
 460 static void clock_tree_show_one(struct seq_file *s, struct clk *c, int level)
 461 {
 462         struct clk *child;
 463         const char *state = "uninit";
 464         char div[8] = {0};
 465
 466         if (c->state == ON)
 467                 state = "on";
 468         else if (c->state == OFF)
 469                 state = "off";
 470
 471         if (c->mul != 0 && c->div != 0) {
 472                 if (c->mul > c->div) {
 473                         int mul = c->mul / c->div;
 474                         int mul2 = (c->mul * 10 / c->div) % 10;
 475                         int mul3 = (c->mul * 10) % c->div;
 476                         if (mul2 == 0 && mul3 == 0)
 477                                 snprintf(div, sizeof(div), "x%d", mul);
 478                         else if (mul3 == 0)
 479                                 snprintf(div, sizeof(div), "x%d.%d", mul, mul2);
 480                         else
 481                                 snprintf(div, sizeof(div), "x%d.%d..", mul, mul2);
 482                 } else {
 483                         snprintf(div, sizeof(div), "%d%s", c->div / c->mul,
 484                                 (c->div % c->mul) ? ".5" : "");
 485                 }
 486         }
 487
 488         seq_printf(s, "%*s%c%c%-*s %-6s %-3d %-8s %-10lu\n",
 489                 level * 3 + 1, "",
 490                 c->rate > c->max_rate ? '!' : ' ',
 491                 !c->set ? '*' : ' ',
 492                 30 - level * 3, c->name,
 493                 state, c->refcnt, div, clk_get_rate_all_locked(c));
 494
 495         list_for_each_entry(child, &clocks, node) {
 496                 if (child->parent != c)
 497                         continue;
 498
 499                 clock_tree_show_one(s, child, level + 1);
 500         }
 501 }
 502
 503 static int clock_tree_show(struct seq_file *s, void *data)
 504 {
 505         struct clk *c;
 506         seq_printf(s, "   clock                          state  ref div      rate\n");
 507         seq_printf(s, "--------------------------------------------------------------\n");
 508
 509         mutex_lock(&clock_list_lock);
 510
 511         clk_lock_all();
 512
 513         list_for_each_entry(c, &clocks, node)
 514                 if (c->parent == NULL)
 515                         clock_tree_show_one(s, c, 0);
 516
 517         clk_unlock_all();
 518
 519         mutex_unlock(&clock_list_lock);
 520         return 0;
 521 }
 522
 523 static int clock_tree_open(struct inode *inode, struct file *file)
 524 {
 525         return single_open(file, clock_tree_show, inode->i_private);
 526 }
 527
 528 static const struct file_operations clock_tree_fops = {
 529         .open           = clock_tree_open,
 530         .read           = seq_read,
 531         .llseek         = seq_lseek,
 532         .release        = single_release,
 533 };
 534
 535 static int possible_parents_show(struct seq_file *s, void *data)
 536 {
 537         struct clk *c = s->private;
 538         int i;
 539
 540         for (i = 0; c->inputs[i].input; i++) {
 541                 char *first = (i == 0) ? "" : " ";
 542                 seq_printf(s, "%s%s", first, c->inputs[i].input->name);
 543         }
 544         seq_printf(s, "\n");
 545         return 0;
 546 }
 547
 548 static int possible_parents_open(struct inode *inode, struct file *file)
 549 {
 550         return single_open(file, possible_parents_show, inode->i_private);
 551 }
 552
 553 static const struct file_operations possible_parents_fops = {
 554         .open           = possible_parents_open,
 555         .read           = seq_read,
 556         .llseek         = seq_lseek,
 557         .release        = single_release,
 558 };
 559
 560 static int clk_debugfs_register_one(struct clk *c)
 561 {
 562         struct dentry *d, *child, *child_tmp;
 563
 564         d = debugfs_create_dir(c->name, clk_debugfs_root);
 565         if (!d)
 566                 return -ENOMEM;
 567         c->dent = d;
 568
 569         d = debugfs_create_u8("refcnt", S_IRUGO, c->dent, (u8 *)&c->refcnt);
 570         if (!d)
 571                 goto err_out;
 572
 573         d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
 574         if (!d)
 575                 goto err_out;
 576
 577         d = debugfs_create_x32("flags", S_IRUGO, c->dent, (u32 *)&c->flags);
 578         if (!d)
 579                 goto err_out;
 580
 581         if (c->inputs) {
 582                 d = debugfs_create_file("possible_parents", S_IRUGO, c->dent,
 583                         c, &possible_parents_fops);
 584                 if (!d)
 585                         goto err_out;
 586         }
 587
 588         return 0;
 589
 590 err_out:
 591         d = c->dent;
 592         list_for_each_entry_safe(child, child_tmp, &d->d_subdirs, d_u.d_child)
 593                 debugfs_remove(child);
 594         debugfs_remove(c->dent);
 595         return -ENOMEM;
 596 }
 597
 598 static int clk_debugfs_register(struct clk *c)
 599 {
 600         int err;
 601         struct clk *pa = c->parent;
 602
 603         if (pa && !pa->dent) {
 604                 err = clk_debugfs_register(pa);
 605                 if (err)
 606                         return err;
 607         }
 608
 609         if (!c->dent) {
 610                 err = clk_debugfs_register_one(c);
 611                 if (err)
 612                         return err;
 613         }
 614         return 0;
 615 }
 616
 617 static int __init clk_debugfs_init(void)
 618 {
 619         struct clk *c;
 620         struct dentry *d;
 621         int err = -ENOMEM;
 622
 623         d = debugfs_create_dir("clock", NULL);
 624         if (!d)
 625                 return -ENOMEM;
 626         clk_debugfs_root = d;
 627
 628         d = debugfs_create_file("clock_tree", S_IRUGO, clk_debugfs_root, NULL,
 629                 &clock_tree_fops);
 630         if (!d)
 631                 goto err_out;
 632
 633         list_for_each_entry(c, &clocks, node) {
 634                 err = clk_debugfs_register(c);
 635                 if (err)
 636                         goto err_out;
 637         }
 638         return 0;
 639 err_out:
 640         debugfs_remove_recursive(clk_debugfs_root);
 641         return err;
 642 }
 643
 644 late_initcall(clk_debugfs_init);
 645 #endif