drivers/clk/tegra/clk-tegra124-emc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * drivers/clk/tegra/clk-emc.c
   4  *
   5  * Copyright (c) 2014, NVIDIA CORPORATION.  All rights reserved.
   6  *
   7  * Author:
   8  *      Mikko Perttunen <mperttunen@nvidia.com>
   9  */
  10
  11 #include <linux/clk-provider.h>
  12 #include <linux/clk.h>
  13 #include <linux/clkdev.h>
  14 #include <linux/delay.h>
  15 #include <linux/io.h>
  16 #include <linux/module.h>
  17 #include <linux/of_address.h>
  18 #include <linux/of_platform.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/sort.h>
  21 #include <linux/string.h>
  22
  23 #include <soc/tegra/fuse.h>
  24 #include <soc/tegra/emc.h>
  25
  26 #include "clk.h"
  27
  28 #define CLK_SOURCE_EMC 0x19c
  29
  30 #define CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_SHIFT 0
  31 #define CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_MASK 0xff
  32 #define CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR(x) (((x) & CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_MASK) << \
  33                                               CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_SHIFT)
  34
  35 #define CLK_SOURCE_EMC_EMC_2X_CLK_SRC_SHIFT 29
  36 #define CLK_SOURCE_EMC_EMC_2X_CLK_SRC_MASK 0x7
  37 #define CLK_SOURCE_EMC_EMC_2X_CLK_SRC(x) (((x) & CLK_SOURCE_EMC_EMC_2X_CLK_SRC_MASK) << \
  38                                           CLK_SOURCE_EMC_EMC_2X_CLK_SRC_SHIFT)
  39
  40 static const char * const emc_parent_clk_names[] = {
  41         "pll_m", "pll_c", "pll_p", "clk_m", "pll_m_ud",
  42         "pll_c2", "pll_c3", "pll_c_ud"
  43 };
  44
  45 /*
  46  * List of clock sources for various parents the EMC clock can have.
  47  * When we change the timing to a timing with a parent that has the same
  48  * clock source as the current parent, we must first change to a backup
  49  * timing that has a different clock source.
  50  */
  51
  52 #define EMC_SRC_PLL_M 0
  53 #define EMC_SRC_PLL_C 1
  54 #define EMC_SRC_PLL_P 2
  55 #define EMC_SRC_CLK_M 3
  56 #define EMC_SRC_PLL_C2 4
  57 #define EMC_SRC_PLL_C3 5
  58
  59 static const char emc_parent_clk_sources[] = {
  60         EMC_SRC_PLL_M, EMC_SRC_PLL_C, EMC_SRC_PLL_P, EMC_SRC_CLK_M,
  61         EMC_SRC_PLL_M, EMC_SRC_PLL_C2, EMC_SRC_PLL_C3, EMC_SRC_PLL_C
  62 };
  63
  64 struct emc_timing {
  65         unsigned long rate, parent_rate;
  66         u8 parent_index;
  67         struct clk *parent;
  68         u32 ram_code;
  69 };
  70
  71 struct tegra_clk_emc {
  72         struct clk_hw hw;
  73         void __iomem *clk_regs;
  74         struct clk *prev_parent;
  75         bool changing_timing;
  76
  77         struct device_node *emc_node;
  78         struct tegra_emc *emc;
  79
  80         int num_timings;
  81         struct emc_timing *timings;
  82         spinlock_t *lock;
  83 };
  84
  85 /* Common clock framework callback implementations */
  86
  87 static unsigned long emc_recalc_rate(struct clk_hw *hw,
  88                                      unsigned long parent_rate)
  89 {
  90         struct tegra_clk_emc *tegra;
  91         u32 val, div;
  92
  93         tegra = container_of(hw, struct tegra_clk_emc, hw);
  94
  95         /*
  96          * CCF wrongly assumes that the parent won't change during set_rate,
  97          * so get the parent rate explicitly.
  98          */
  99         parent_rate = clk_hw_get_rate(clk_hw_get_parent(hw));
 100
 101         val = readl(tegra->clk_regs + CLK_SOURCE_EMC);
 102         div = val & CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR_MASK;
 103
 104         return parent_rate / (div + 2) * 2;
 105 }
 106
 107 /*
 108  * Rounds up unless no higher rate exists, in which case down. This way is
 109  * safer since things have EMC rate floors. Also don't touch parent_rate
 110  * since we don't want the CCF to play with our parent clocks.
 111  */
 112 static int emc_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
 113 {
 114         struct tegra_clk_emc *tegra;
 115         u8 ram_code = tegra_read_ram_code();
 116         struct emc_timing *timing = NULL;
 117         int i, k, t;
 118
 119         tegra = container_of(hw, struct tegra_clk_emc, hw);
 120
 121         for (k = 0; k < tegra->num_timings; k++) {
 122                 if (tegra->timings[k].ram_code == ram_code)
 123                         break;
 124         }
 125
 126         for (t = k; t < tegra->num_timings; t++) {
 127                 if (tegra->timings[t].ram_code != ram_code)
 128                         break;
 129         }
 130
 131         for (i = k; i < t; i++) {
 132                 timing = tegra->timings + i;
 133
 134                 if (timing->rate < req->rate && i != t - 1)
 135                         continue;
 136
 137                 if (timing->rate > req->max_rate) {
 138                         i = max(i, k + 1);
 139                         req->rate = tegra->timings[i - 1].rate;
 140                         return 0;
 141                 }
 142
 143                 if (timing->rate < req->min_rate)
 144                         continue;
 145
 146                 req->rate = timing->rate;
 147                 return 0;
 148         }
 149
 150         if (timing) {
 151                 req->rate = timing->rate;
 152                 return 0;
 153         }
 154
 155         req->rate = clk_hw_get_rate(hw);
 156         return 0;
 157 }
 158
 159 static u8 emc_get_parent(struct clk_hw *hw)
 160 {
 161         struct tegra_clk_emc *tegra;
 162         u32 val;
 163
 164         tegra = container_of(hw, struct tegra_clk_emc, hw);
 165
 166         val = readl(tegra->clk_regs + CLK_SOURCE_EMC);
 167
 168         return (val >> CLK_SOURCE_EMC_EMC_2X_CLK_SRC_SHIFT)
 169                 & CLK_SOURCE_EMC_EMC_2X_CLK_SRC_MASK;
 170 }
 171
 172 static struct tegra_emc *emc_ensure_emc_driver(struct tegra_clk_emc *tegra)
 173 {
 174         struct platform_device *pdev;
 175
 176         if (tegra->emc)
 177                 return tegra->emc;
 178
 179         if (!tegra->emc_node)
 180                 return NULL;
 181
 182         pdev = of_find_device_by_node(tegra->emc_node);
 183         if (!pdev) {
 184                 pr_err("%s: could not get external memory controller\n",
 185                        __func__);
 186                 return NULL;
 187         }
 188
 189         of_node_put(tegra->emc_node);
 190         tegra->emc_node = NULL;
 191
 192         tegra->emc = platform_get_drvdata(pdev);
 193         if (!tegra->emc) {
 194                 put_device(&pdev->dev);
 195                 pr_err("%s: cannot find EMC driver\n", __func__);
 196                 return NULL;
 197         }
 198
 199         return tegra->emc;
 200 }
 201
 202 static int emc_set_timing(struct tegra_clk_emc *tegra,
 203                           struct emc_timing *timing)
 204 {
 205         int err;
 206         u8 div;
 207         u32 car_value;
 208         unsigned long flags = 0;
 209         struct tegra_emc *emc = emc_ensure_emc_driver(tegra);
 210
 211         if (!emc)
 212                 return -ENOENT;
 213
 214         pr_debug("going to rate %ld prate %ld p %s\n", timing->rate,
 215                  timing->parent_rate, __clk_get_name(timing->parent));
 216
 217         if (emc_get_parent(&tegra->hw) == timing->parent_index &&
 218             clk_get_rate(timing->parent) != timing->parent_rate) {
 219                 WARN_ONCE(1, "parent %s rate mismatch %lu %lu\n",
 220                           __clk_get_name(timing->parent),
 221                           clk_get_rate(timing->parent),
 222                           timing->parent_rate);
 223                 return -EINVAL;
 224         }
 225
 226         tegra->changing_timing = true;
 227
 228         err = clk_set_rate(timing->parent, timing->parent_rate);
 229         if (err) {
 230                 pr_err("cannot change parent %s rate to %ld: %d\n",
 231                        __clk_get_name(timing->parent), timing->parent_rate,
 232                        err);
 233
 234                 return err;
 235         }
 236
 237         err = clk_prepare_enable(timing->parent);
 238         if (err) {
 239                 pr_err("cannot enable parent clock: %d\n", err);
 240                 return err;
 241         }
 242
 243         div = timing->parent_rate / (timing->rate / 2) - 2;
 244
 245         err = tegra_emc_prepare_timing_change(emc, timing->rate);
 246         if (err)
 247                 return err;
 248
 249         spin_lock_irqsave(tegra->lock, flags);
 250
 251         car_value = readl(tegra->clk_regs + CLK_SOURCE_EMC);
 252
 253         car_value &= ~CLK_SOURCE_EMC_EMC_2X_CLK_SRC(~0);
 254         car_value |= CLK_SOURCE_EMC_EMC_2X_CLK_SRC(timing->parent_index);
 255
 256         car_value &= ~CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR(~0);
 257         car_value |= CLK_SOURCE_EMC_EMC_2X_CLK_DIVISOR(div);
 258
 259         writel(car_value, tegra->clk_regs + CLK_SOURCE_EMC);
 260
 261         spin_unlock_irqrestore(tegra->lock, flags);
 262
 263         tegra_emc_complete_timing_change(emc, timing->rate);
 264
 265         clk_hw_reparent(&tegra->hw, __clk_get_hw(timing->parent));
 266         clk_disable_unprepare(tegra->prev_parent);
 267
 268         tegra->prev_parent = timing->parent;
 269         tegra->changing_timing = false;
 270
 271         return 0;
 272 }
 273
 274 /*
 275  * Get backup timing to use as an intermediate step when a change between
 276  * two timings with the same clock source has been requested. First try to
 277  * find a timing with a higher clock rate to avoid a rate below any set rate
 278  * floors. If that is not possible, find a lower rate.
 279  */
 280 static struct emc_timing *get_backup_timing(struct tegra_clk_emc *tegra,
 281                                             int timing_index)
 282 {
 283         int i;
 284         u32 ram_code = tegra_read_ram_code();
 285         struct emc_timing *timing;
 286
 287         for (i = timing_index+1; i < tegra->num_timings; i++) {
 288                 timing = tegra->timings + i;
 289                 if (timing->ram_code != ram_code)
 290                         break;
 291
 292                 if (emc_parent_clk_sources[timing->parent_index] !=
 293                     emc_parent_clk_sources[
 294                       tegra->timings[timing_index].parent_index])
 295                         return timing;
 296         }
 297
 298         for (i = timing_index-1; i >= 0; --i) {
 299                 timing = tegra->timings + i;
 300                 if (timing->ram_code != ram_code)
 301                         break;
 302
 303                 if (emc_parent_clk_sources[timing->parent_index] !=
 304                     emc_parent_clk_sources[
 305                       tegra->timings[timing_index].parent_index])
 306                         return timing;
 307         }
 308
 309         return NULL;
 310 }
 311
 312 static int emc_set_rate(struct clk_hw *hw, unsigned long rate,
 313                         unsigned long parent_rate)
 314 {
 315         struct tegra_clk_emc *tegra;
 316         struct emc_timing *timing = NULL;
 317         int i, err;
 318         u32 ram_code = tegra_read_ram_code();
 319
 320         tegra = container_of(hw, struct tegra_clk_emc, hw);
 321
 322         if (clk_hw_get_rate(hw) == rate)
 323                 return 0;
 324
 325         /*
 326          * When emc_set_timing changes the parent rate, CCF will propagate
 327          * that downward to us, so ignore any set_rate calls while a rate
 328          * change is already going on.
 329          */
 330         if (tegra->changing_timing)
 331                 return 0;
 332
 333         for (i = 0; i < tegra->num_timings; i++) {
 334                 if (tegra->timings[i].rate == rate &&
 335                     tegra->timings[i].ram_code == ram_code) {
 336                         timing = tegra->timings + i;
 337                         break;
 338                 }
 339         }
 340
 341         if (!timing) {
 342                 pr_err("cannot switch to rate %ld without emc table\n", rate);
 343                 return -EINVAL;
 344         }
 345
 346         if (emc_parent_clk_sources[emc_get_parent(hw)] ==
 347             emc_parent_clk_sources[timing->parent_index] &&
 348             clk_get_rate(timing->parent) != timing->parent_rate) {
 349                 /*
 350                  * Parent clock source not changed but parent rate has changed,
 351                  * need to temporarily switch to another parent
 352                  */
 353
 354                 struct emc_timing *backup_timing;
 355
 356                 backup_timing = get_backup_timing(tegra, i);
 357                 if (!backup_timing) {
 358                         pr_err("cannot find backup timing\n");
 359                         return -EINVAL;
 360                 }
 361
 362                 pr_debug("using %ld as backup rate when going to %ld\n",
 363                          backup_timing->rate, rate);
 364
 365                 err = emc_set_timing(tegra, backup_timing);
 366                 if (err) {
 367                         pr_err("cannot set backup timing: %d\n", err);
 368                         return err;
 369                 }
 370         }
 371
 372         return emc_set_timing(tegra, timing);
 373 }
 374
 375 /* Initialization and deinitialization */
 376
 377 static int load_one_timing_from_dt(struct tegra_clk_emc *tegra,
 378                                    struct emc_timing *timing,
 379                                    struct device_node *node)
 380 {
 381         int err, i;
 382         u32 tmp;
 383
 384         err = of_property_read_u32(node, "clock-frequency", &tmp);
 385         if (err) {
 386                 pr_err("timing %pOF: failed to read rate\n", node);
 387                 return err;
 388         }
 389
 390         timing->rate = tmp;
 391
 392         err = of_property_read_u32(node, "nvidia,parent-clock-frequency", &tmp);
 393         if (err) {
 394                 pr_err("timing %pOF: failed to read parent rate\n", node);
 395                 return err;
 396         }
 397
 398         timing->parent_rate = tmp;
 399
 400         timing->parent = of_clk_get_by_name(node, "emc-parent");
 401         if (IS_ERR(timing->parent)) {
 402                 pr_err("timing %pOF: failed to get parent clock\n", node);
 403                 return PTR_ERR(timing->parent);
 404         }
 405
 406         timing->parent_index = 0xff;
 407         i = match_string(emc_parent_clk_names, ARRAY_SIZE(emc_parent_clk_names),
 408                          __clk_get_name(timing->parent));
 409         if (i < 0) {
 410                 pr_err("timing %pOF: %s is not a valid parent\n",
 411                        node, __clk_get_name(timing->parent));
 412                 clk_put(timing->parent);
 413                 return -EINVAL;
 414         }
 415
 416         timing->parent_index = i;
 417         return 0;
 418 }
 419
 420 static int cmp_timings(const void *_a, const void *_b)
 421 {
 422         const struct emc_timing *a = _a;
 423         const struct emc_timing *b = _b;
 424
 425         if (a->rate < b->rate)
 426                 return -1;
 427         else if (a->rate == b->rate)
 428                 return 0;
 429         else
 430                 return 1;
 431 }
 432
 433 static int load_timings_from_dt(struct tegra_clk_emc *tegra,
 434                                 struct device_node *node,
 435                                 u32 ram_code)
 436 {
 437         struct emc_timing *timings_ptr;
 438         struct device_node *child;
 439         int child_count = of_get_child_count(node);
 440         int i = 0, err;
 441         size_t size;
 442
 443         size = (tegra->num_timings + child_count) * sizeof(struct emc_timing);
 444
 445         tegra->timings = krealloc(tegra->timings, size, GFP_KERNEL);
 446         if (!tegra->timings)
 447                 return -ENOMEM;
 448
 449         timings_ptr = tegra->timings + tegra->num_timings;
 450         tegra->num_timings += child_count;
 451
 452         for_each_child_of_node(node, child) {
 453                 struct emc_timing *timing = timings_ptr + (i++);
 454
 455                 err = load_one_timing_from_dt(tegra, timing, child);
 456                 if (err) {
 457                         of_node_put(child);
 458                         kfree(tegra->timings);
 459                         return err;
 460                 }
 461
 462                 timing->ram_code = ram_code;
 463         }
 464
 465         sort(timings_ptr, child_count, sizeof(struct emc_timing),
 466              cmp_timings, NULL);
 467
 468         return 0;
 469 }
 470
 471 static const struct clk_ops tegra_clk_emc_ops = {
 472         .recalc_rate = emc_recalc_rate,
 473         .determine_rate = emc_determine_rate,
 474         .set_rate = emc_set_rate,
 475         .get_parent = emc_get_parent,
 476 };
 477
 478 struct clk *tegra_clk_register_emc(void __iomem *base, struct device_node *np,
 479                                    spinlock_t *lock)
 480 {
 481         struct tegra_clk_emc *tegra;
 482         struct clk_init_data init;
 483         struct device_node *node;
 484         u32 node_ram_code;
 485         struct clk *clk;
 486         int err;
 487
 488         tegra = kcalloc(1, sizeof(*tegra), GFP_KERNEL);
 489         if (!tegra)
 490                 return ERR_PTR(-ENOMEM);
 491
 492         tegra->clk_regs = base;
 493         tegra->lock = lock;
 494
 495         tegra->num_timings = 0;
 496
 497         for_each_child_of_node(np, node) {
 498                 err = of_property_read_u32(node, "nvidia,ram-code",
 499                                            &node_ram_code);
 500                 if (err)
 501                         continue;
 502
 503                 /*
 504                  * Store timings for all ram codes as we cannot read the
 505                  * fuses until the apbmisc driver is loaded.
 506                  */
 507                 err = load_timings_from_dt(tegra, node, node_ram_code);
 508                 if (err) {
 509                         of_node_put(node);
 510                         kfree(tegra);
 511                         return ERR_PTR(err);
 512                 }
 513         }
 514
 515         if (tegra->num_timings == 0)
 516                 pr_warn("%s: no memory timings registered\n", __func__);
 517
 518         tegra->emc_node = of_parse_phandle(np,
 519                         "nvidia,external-memory-controller", 0);
 520         if (!tegra->emc_node)
 521                 pr_warn("%s: couldn't find node for EMC driver\n", __func__);
 522
 523         init.name = "emc";
 524         init.ops = &tegra_clk_emc_ops;
 525         init.flags = CLK_IS_CRITICAL;
 526         init.parent_names = emc_parent_clk_names;
 527         init.num_parents = ARRAY_SIZE(emc_parent_clk_names);
 528
 529         tegra->hw.init = &init;
 530
 531         clk = clk_register(NULL, &tegra->hw);
 532         if (IS_ERR(clk))
 533                 return clk;
 534
 535         tegra->prev_parent = clk_hw_get_parent_by_index(
 536                 &tegra->hw, emc_get_parent(&tegra->hw))->clk;
 537         tegra->changing_timing = false;
 538
 539         /* Allow debugging tools to see the EMC clock */
 540         clk_register_clkdev(clk, "emc", "tegra-clk-debug");
 541
 542         return clk;
 543 };