drivers/clk/ti/divider.c

   1 /*
   2  * TI Divider Clock
   3  *
   4  * Copyright (C) 2013 Texas Instruments, Inc.
   5  *
   6  * Tero Kristo <t-kristo@ti.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  13  * kind, whether express or implied; without even the implied warranty
  14  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #include <linux/clk-provider.h>
  19 #include <linux/slab.h>
  20 #include <linux/err.h>
  21 #include <linux/of.h>
  22 #include <linux/of_address.h>
  23 #include <linux/clk/ti.h>
  24
  25 #undef pr_fmt
  26 #define pr_fmt(fmt) "%s: " fmt, __func__
  27
  28 #define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
  29
  30 #define div_mask(d)     ((1 << ((d)->width)) - 1)
  31
  32 static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
  33 {
  34         unsigned int maxdiv = 0;
  35         const struct clk_div_table *clkt;
  36
  37         for (clkt = table; clkt->div; clkt++)
  38                 if (clkt->div > maxdiv)
  39                         maxdiv = clkt->div;
  40         return maxdiv;
  41 }
  42
  43 static unsigned int _get_maxdiv(struct clk_divider *divider)
  44 {
  45         if (divider->flags & CLK_DIVIDER_ONE_BASED)
  46                 return div_mask(divider);
  47         if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
  48                 return 1 << div_mask(divider);
  49         if (divider->table)
  50                 return _get_table_maxdiv(divider->table);
  51         return div_mask(divider) + 1;
  52 }
  53
  54 static unsigned int _get_table_div(const struct clk_div_table *table,
  55                                    unsigned int val)
  56 {
  57         const struct clk_div_table *clkt;
  58
  59         for (clkt = table; clkt->div; clkt++)
  60                 if (clkt->val == val)
  61                         return clkt->div;
  62         return 0;
  63 }
  64
  65 static unsigned int _get_div(struct clk_divider *divider, unsigned int val)
  66 {
  67         if (divider->flags & CLK_DIVIDER_ONE_BASED)
  68                 return val;
  69         if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
  70                 return 1 << val;
  71         if (divider->table)
  72                 return _get_table_div(divider->table, val);
  73         return val + 1;
  74 }
  75
  76 static unsigned int _get_table_val(const struct clk_div_table *table,
  77                                    unsigned int div)
  78 {
  79         const struct clk_div_table *clkt;
  80
  81         for (clkt = table; clkt->div; clkt++)
  82                 if (clkt->div == div)
  83                         return clkt->val;
  84         return 0;
  85 }
  86
  87 static unsigned int _get_val(struct clk_divider *divider, u8 div)
  88 {
  89         if (divider->flags & CLK_DIVIDER_ONE_BASED)
  90                 return div;
  91         if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
  92                 return __ffs(div);
  93         if (divider->table)
  94                 return  _get_table_val(divider->table, div);
  95         return div - 1;
  96 }
  97
  98 static unsigned long ti_clk_divider_recalc_rate(struct clk_hw *hw,
  99                                                 unsigned long parent_rate)
 100 {
 101         struct clk_divider *divider = to_clk_divider(hw);
 102         unsigned int div, val;
 103
 104         val = ti_clk_ll_ops->clk_readl(divider->reg) >> divider->shift;
 105         val &= div_mask(divider);
 106
 107         div = _get_div(divider, val);
 108         if (!div) {
 109                 WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
 110                      "%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
 111                      __clk_get_name(hw->clk));
 112                 return parent_rate;
 113         }
 114
 115         return DIV_ROUND_UP(parent_rate, div);
 116 }
 117
 118 /*
 119  * The reverse of DIV_ROUND_UP: The maximum number which
 120  * divided by m is r
 121  */
 122 #define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)
 123
 124 static bool _is_valid_table_div(const struct clk_div_table *table,
 125                                 unsigned int div)
 126 {
 127         const struct clk_div_table *clkt;
 128
 129         for (clkt = table; clkt->div; clkt++)
 130                 if (clkt->div == div)
 131                         return true;
 132         return false;
 133 }
 134
 135 static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
 136 {
 137         if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
 138                 return is_power_of_2(div);
 139         if (divider->table)
 140                 return _is_valid_table_div(divider->table, div);
 141         return true;
 142 }
 143
 144 static int ti_clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
 145                                   unsigned long *best_parent_rate)
 146 {
 147         struct clk_divider *divider = to_clk_divider(hw);
 148         int i, bestdiv = 0;
 149         unsigned long parent_rate, best = 0, now, maxdiv;
 150         unsigned long parent_rate_saved = *best_parent_rate;
 151
 152         if (!rate)
 153                 rate = 1;
 154
 155         maxdiv = _get_maxdiv(divider);
 156
 157         if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
 158                 parent_rate = *best_parent_rate;
 159                 bestdiv = DIV_ROUND_UP(parent_rate, rate);
 160                 bestdiv = bestdiv == 0 ? 1 : bestdiv;
 161                 bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
 162                 return bestdiv;
 163         }
 164
 165         /*
 166          * The maximum divider we can use without overflowing
 167          * unsigned long in rate * i below
 168          */
 169         maxdiv = min(ULONG_MAX / rate, maxdiv);
 170
 171         for (i = 1; i <= maxdiv; i++) {
 172                 if (!_is_valid_div(divider, i))
 173                         continue;
 174                 if (rate * i == parent_rate_saved) {
 175                         /*
 176                          * It's the most ideal case if the requested rate can be
 177                          * divided from parent clock without needing to change
 178                          * parent rate, so return the divider immediately.
 179                          */
 180                         *best_parent_rate = parent_rate_saved;
 181                         return i;
 182                 }
 183                 parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
 184                                 MULT_ROUND_UP(rate, i));
 185                 now = DIV_ROUND_UP(parent_rate, i);
 186                 if (now <= rate && now > best) {
 187                         bestdiv = i;
 188                         best = now;
 189                         *best_parent_rate = parent_rate;
 190                 }
 191         }
 192
 193         if (!bestdiv) {
 194                 bestdiv = _get_maxdiv(divider);
 195                 *best_parent_rate =
 196                         __clk_round_rate(__clk_get_parent(hw->clk), 1);
 197         }
 198
 199         return bestdiv;
 200 }
 201
 202 static long ti_clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
 203                                       unsigned long *prate)
 204 {
 205         int div;
 206         div = ti_clk_divider_bestdiv(hw, rate, prate);
 207
 208         return DIV_ROUND_UP(*prate, div);
 209 }
 210
 211 static int ti_clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
 212                                    unsigned long parent_rate)
 213 {
 214         struct clk_divider *divider = to_clk_divider(hw);
 215         unsigned int div, value;
 216         unsigned long flags = 0;
 217         u32 val;
 218
 219         div = DIV_ROUND_UP(parent_rate, rate);
 220         value = _get_val(divider, div);
 221
 222         if (value > div_mask(divider))
 223                 value = div_mask(divider);
 224
 225         if (divider->lock)
 226                 spin_lock_irqsave(divider->lock, flags);
 227
 228         if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
 229                 val = div_mask(divider) << (divider->shift + 16);
 230         } else {
 231                 val = ti_clk_ll_ops->clk_readl(divider->reg);
 232                 val &= ~(div_mask(divider) << divider->shift);
 233         }
 234         val |= value << divider->shift;
 235         ti_clk_ll_ops->clk_writel(val, divider->reg);
 236
 237         if (divider->lock)
 238                 spin_unlock_irqrestore(divider->lock, flags);
 239
 240         return 0;
 241 }
 242
 243 const struct clk_ops ti_clk_divider_ops = {
 244         .recalc_rate = ti_clk_divider_recalc_rate,
 245         .round_rate = ti_clk_divider_round_rate,
 246         .set_rate = ti_clk_divider_set_rate,
 247 };
 248
 249 static struct clk *_register_divider(struct device *dev, const char *name,
 250                                      const char *parent_name,
 251                                      unsigned long flags, void __iomem *reg,
 252                                      u8 shift, u8 width, u8 clk_divider_flags,
 253                                      const struct clk_div_table *table,
 254                                      spinlock_t *lock)
 255 {
 256         struct clk_divider *div;
 257         struct clk *clk;
 258         struct clk_init_data init;
 259
 260         if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
 261                 if (width + shift > 16) {
 262                         pr_warn("divider value exceeds LOWORD field\n");
 263                         return ERR_PTR(-EINVAL);
 264                 }
 265         }
 266
 267         /* allocate the divider */
 268         div = kzalloc(sizeof(*div), GFP_KERNEL);
 269         if (!div) {
 270                 pr_err("%s: could not allocate divider clk\n", __func__);
 271                 return ERR_PTR(-ENOMEM);
 272         }
 273
 274         init.name = name;
 275         init.ops = &ti_clk_divider_ops;
 276         init.flags = flags | CLK_IS_BASIC;
 277         init.parent_names = (parent_name ? &parent_name : NULL);
 278         init.num_parents = (parent_name ? 1 : 0);
 279
 280         /* struct clk_divider assignments */
 281         div->reg = reg;
 282         div->shift = shift;
 283         div->width = width;
 284         div->flags = clk_divider_flags;
 285         div->lock = lock;
 286         div->hw.init = &init;
 287         div->table = table;
 288
 289         /* register the clock */
 290         clk = clk_register(dev, &div->hw);
 291
 292         if (IS_ERR(clk))
 293                 kfree(div);
 294
 295         return clk;
 296 }
 297
 298 static struct clk_div_table
 299 __init *ti_clk_get_div_table(struct device_node *node)
 300 {
 301         struct clk_div_table *table;
 302         const __be32 *divspec;
 303         u32 val;
 304         u32 num_div;
 305         u32 valid_div;
 306         int i;
 307
 308         divspec = of_get_property(node, "ti,dividers", &num_div);
 309
 310         if (!divspec)
 311                 return NULL;
 312
 313         num_div /= 4;
 314
 315         valid_div = 0;
 316
 317         /* Determine required size for divider table */
 318         for (i = 0; i < num_div; i++) {
 319                 of_property_read_u32_index(node, "ti,dividers", i, &val);
 320                 if (val)
 321                         valid_div++;
 322         }
 323
 324         if (!valid_div) {
 325                 pr_err("no valid dividers for %s table\n", node->name);
 326                 return ERR_PTR(-EINVAL);
 327         }
 328
 329         table = kzalloc(sizeof(*table) * (valid_div + 1), GFP_KERNEL);
 330
 331         if (!table)
 332                 return ERR_PTR(-ENOMEM);
 333
 334         valid_div = 0;
 335
 336         for (i = 0; i < num_div; i++) {
 337                 of_property_read_u32_index(node, "ti,dividers", i, &val);
 338                 if (val) {
 339                         table[valid_div].div = val;
 340                         table[valid_div].val = i;
 341                         valid_div++;
 342                 }
 343         }
 344
 345         return table;
 346 }
 347
 348 static int _get_divider_width(struct device_node *node,
 349                               const struct clk_div_table *table,
 350                               u8 flags)
 351 {
 352         u32 min_div;
 353         u32 max_div;
 354         u32 val = 0;
 355         u32 div;
 356
 357         if (!table) {
 358                 /* Clk divider table not provided, determine min/max divs */
 359                 if (of_property_read_u32(node, "ti,min-div", &min_div))
 360                         min_div = 1;
 361
 362                 if (of_property_read_u32(node, "ti,max-div", &max_div)) {
 363                         pr_err("no max-div for %s!\n", node->name);
 364                         return -EINVAL;
 365                 }
 366
 367                 /* Determine bit width for the field */
 368                 if (flags & CLK_DIVIDER_ONE_BASED)
 369                         val = 1;
 370
 371                 div = min_div;
 372
 373                 while (div < max_div) {
 374                         if (flags & CLK_DIVIDER_POWER_OF_TWO)
 375                                 div <<= 1;
 376                         else
 377                                 div++;
 378                         val++;
 379                 }
 380         } else {
 381                 div = 0;
 382
 383                 while (table[div].div) {
 384                         val = table[div].val;
 385                         div++;
 386                 }
 387         }
 388
 389         return fls(val);
 390 }
 391
 392 static int __init ti_clk_divider_populate(struct device_node *node,
 393         void __iomem **reg, const struct clk_div_table **table,
 394         u32 *flags, u8 *div_flags, u8 *width, u8 *shift)
 395 {
 396         u32 val;
 397
 398         *reg = ti_clk_get_reg_addr(node, 0);
 399         if (!*reg)
 400                 return -EINVAL;
 401
 402         if (!of_property_read_u32(node, "ti,bit-shift", &val))
 403                 *shift = val;
 404         else
 405                 *shift = 0;
 406
 407         *flags = 0;
 408         *div_flags = 0;
 409
 410         if (of_property_read_bool(node, "ti,index-starts-at-one"))
 411                 *div_flags |= CLK_DIVIDER_ONE_BASED;
 412
 413         if (of_property_read_bool(node, "ti,index-power-of-two"))
 414                 *div_flags |= CLK_DIVIDER_POWER_OF_TWO;
 415
 416         if (of_property_read_bool(node, "ti,set-rate-parent"))
 417                 *flags |= CLK_SET_RATE_PARENT;
 418
 419         *table = ti_clk_get_div_table(node);
 420
 421         if (IS_ERR(*table))
 422                 return PTR_ERR(*table);
 423
 424         *width = _get_divider_width(node, *table, *div_flags);
 425
 426         return 0;
 427 }
 428
 429 /**
 430  * of_ti_divider_clk_setup - Setup function for simple div rate clock
 431  * @node: device node for this clock
 432  *
 433  * Sets up a basic divider clock.
 434  */
 435 static void __init of_ti_divider_clk_setup(struct device_node *node)
 436 {
 437         struct clk *clk;
 438         const char *parent_name;
 439         void __iomem *reg;
 440         u8 clk_divider_flags = 0;
 441         u8 width = 0;
 442         u8 shift = 0;
 443         const struct clk_div_table *table = NULL;
 444         u32 flags = 0;
 445
 446         parent_name = of_clk_get_parent_name(node, 0);
 447
 448         if (ti_clk_divider_populate(node, &reg, &table, &flags,
 449                                     &clk_divider_flags, &width, &shift))
 450                 goto cleanup;
 451
 452         clk = _register_divider(NULL, node->name, parent_name, flags, reg,
 453                                 shift, width, clk_divider_flags, table, NULL);
 454
 455         if (!IS_ERR(clk)) {
 456                 of_clk_add_provider(node, of_clk_src_simple_get, clk);
 457                 of_ti_clk_autoidle_setup(node);
 458                 return;
 459         }
 460
 461 cleanup:
 462         kfree(table);
 463 }
 464 CLK_OF_DECLARE(divider_clk, "ti,divider-clock", of_ti_divider_clk_setup);
 465
 466 static void __init of_ti_composite_divider_clk_setup(struct device_node *node)
 467 {
 468         struct clk_divider *div;
 469         u32 val;
 470
 471         div = kzalloc(sizeof(*div), GFP_KERNEL);
 472         if (!div)
 473                 return;
 474
 475         if (ti_clk_divider_populate(node, &div->reg, &div->table, &val,
 476                                     &div->flags, &div->width, &div->shift) < 0)
 477                 goto cleanup;
 478
 479         if (!ti_clk_add_component(node, &div->hw, CLK_COMPONENT_TYPE_DIVIDER))
 480                 return;
 481
 482 cleanup:
 483         kfree(div->table);
 484         kfree(div);
 485 }
 486 CLK_OF_DECLARE(ti_composite_divider_clk, "ti,composite-divider-clock",
 487                of_ti_composite_divider_clk_setup);