drivers/clk/baikal-t1/ccu-div.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
   4  *
   5  * Authors:
   6  *   Serge Semin <Sergey.Semin@baikalelectronics.ru>
   7  *   Dmitry Dunaev <dmitry.dunaev@baikalelectronics.ru>
   8  *
   9  * Baikal-T1 CCU Dividers interface driver
  10  */
  11
  12 #define pr_fmt(fmt) "bt1-ccu-div: " fmt
  13
  14 #include <linux/kernel.h>
  15 #include <linux/printk.h>
  16 #include <linux/bits.h>
  17 #include <linux/bitfield.h>
  18 #include <linux/slab.h>
  19 #include <linux/clk-provider.h>
  20 #include <linux/of.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/regmap.h>
  23 #include <linux/delay.h>
  24 #include <linux/time64.h>
  25 #include <linux/debugfs.h>
  26
  27 #include "ccu-div.h"
  28
  29 #define CCU_DIV_CTL                     0x00
  30 #define CCU_DIV_CTL_EN                  BIT(0)
  31 #define CCU_DIV_CTL_RST                 BIT(1)
  32 #define CCU_DIV_CTL_SET_CLKDIV          BIT(2)
  33 #define CCU_DIV_CTL_CLKDIV_FLD          4
  34 #define CCU_DIV_CTL_CLKDIV_MASK(_width) \
  35         GENMASK((_width) + CCU_DIV_CTL_CLKDIV_FLD - 1, CCU_DIV_CTL_CLKDIV_FLD)
  36 #define CCU_DIV_CTL_LOCK_SHIFTED        BIT(27)
  37 #define CCU_DIV_CTL_LOCK_NORMAL         BIT(31)
  38
  39 #define CCU_DIV_RST_DELAY_US            1
  40 #define CCU_DIV_LOCK_CHECK_RETRIES      50
  41
  42 #define CCU_DIV_CLKDIV_MIN              0
  43 #define CCU_DIV_CLKDIV_MAX(_mask) \
  44         ((_mask) >> CCU_DIV_CTL_CLKDIV_FLD)
  45
  46 /*
  47  * Use the next two methods until there are generic field setter and
  48  * getter available with non-constant mask support.
  49  */
  50 static inline u32 ccu_div_get(u32 mask, u32 val)
  51 {
  52         return (val & mask) >> CCU_DIV_CTL_CLKDIV_FLD;
  53 }
  54
  55 static inline u32 ccu_div_prep(u32 mask, u32 val)
  56 {
  57         return (val << CCU_DIV_CTL_CLKDIV_FLD) & mask;
  58 }
  59
  60 static inline unsigned long ccu_div_lock_delay_ns(unsigned long ref_clk,
  61                                                   unsigned long div)
  62 {
  63         u64 ns = 4ULL * (div ?: 1) * NSEC_PER_SEC;
  64
  65         do_div(ns, ref_clk);
  66
  67         return ns;
  68 }
  69
  70 static inline unsigned long ccu_div_calc_freq(unsigned long ref_clk,
  71                                               unsigned long div)
  72 {
  73         return ref_clk / (div ?: 1);
  74 }
  75
  76 static int ccu_div_var_update_clkdiv(struct ccu_div *div,
  77                                      unsigned long parent_rate,
  78                                      unsigned long divider)
  79 {
  80         unsigned long nd;
  81         u32 val = 0;
  82         u32 lock;
  83         int count;
  84
  85         nd = ccu_div_lock_delay_ns(parent_rate, divider);
  86
  87         if (div->features & CCU_DIV_LOCK_SHIFTED)
  88                 lock = CCU_DIV_CTL_LOCK_SHIFTED;
  89         else
  90                 lock = CCU_DIV_CTL_LOCK_NORMAL;
  91
  92         regmap_update_bits(div->sys_regs, div->reg_ctl,
  93                            CCU_DIV_CTL_SET_CLKDIV, CCU_DIV_CTL_SET_CLKDIV);
  94
  95         /*
  96          * Until there is nsec-version of readl_poll_timeout() is available
  97          * we have to implement the next polling loop.
  98          */
  99         count = CCU_DIV_LOCK_CHECK_RETRIES;
 100         do {
 101                 ndelay(nd);
 102                 regmap_read(div->sys_regs, div->reg_ctl, &val);
 103                 if (val & lock)
 104                         return 0;
 105         } while (--count);
 106
 107         return -ETIMEDOUT;
 108 }
 109
 110 static int ccu_div_var_enable(struct clk_hw *hw)
 111 {
 112         struct clk_hw *parent_hw = clk_hw_get_parent(hw);
 113         struct ccu_div *div = to_ccu_div(hw);
 114         unsigned long flags;
 115         u32 val = 0;
 116         int ret;
 117
 118         if (!parent_hw) {
 119                 pr_err("Can't enable '%s' with no parent", clk_hw_get_name(hw));
 120                 return -EINVAL;
 121         }
 122
 123         regmap_read(div->sys_regs, div->reg_ctl, &val);
 124         if (val & CCU_DIV_CTL_EN)
 125                 return 0;
 126
 127         spin_lock_irqsave(&div->lock, flags);
 128         ret = ccu_div_var_update_clkdiv(div, clk_hw_get_rate(parent_hw),
 129                                         ccu_div_get(div->mask, val));
 130         if (!ret)
 131                 regmap_update_bits(div->sys_regs, div->reg_ctl,
 132                                    CCU_DIV_CTL_EN, CCU_DIV_CTL_EN);
 133         spin_unlock_irqrestore(&div->lock, flags);
 134         if (ret)
 135                 pr_err("Divider '%s' lock timed out\n", clk_hw_get_name(hw));
 136
 137         return ret;
 138 }
 139
 140 static int ccu_div_gate_enable(struct clk_hw *hw)
 141 {
 142         struct ccu_div *div = to_ccu_div(hw);
 143         unsigned long flags;
 144
 145         spin_lock_irqsave(&div->lock, flags);
 146         regmap_update_bits(div->sys_regs, div->reg_ctl,
 147                            CCU_DIV_CTL_EN, CCU_DIV_CTL_EN);
 148         spin_unlock_irqrestore(&div->lock, flags);
 149
 150         return 0;
 151 }
 152
 153 static void ccu_div_gate_disable(struct clk_hw *hw)
 154 {
 155         struct ccu_div *div = to_ccu_div(hw);
 156         unsigned long flags;
 157
 158         spin_lock_irqsave(&div->lock, flags);
 159         regmap_update_bits(div->sys_regs, div->reg_ctl, CCU_DIV_CTL_EN, 0);
 160         spin_unlock_irqrestore(&div->lock, flags);
 161 }
 162
 163 static int ccu_div_gate_is_enabled(struct clk_hw *hw)
 164 {
 165         struct ccu_div *div = to_ccu_div(hw);
 166         u32 val = 0;
 167
 168         regmap_read(div->sys_regs, div->reg_ctl, &val);
 169
 170         return !!(val & CCU_DIV_CTL_EN);
 171 }
 172
 173 static unsigned long ccu_div_var_recalc_rate(struct clk_hw *hw,
 174                                              unsigned long parent_rate)
 175 {
 176         struct ccu_div *div = to_ccu_div(hw);
 177         unsigned long divider;
 178         u32 val = 0;
 179
 180         regmap_read(div->sys_regs, div->reg_ctl, &val);
 181         divider = ccu_div_get(div->mask, val);
 182
 183         return ccu_div_calc_freq(parent_rate, divider);
 184 }
 185
 186 static inline unsigned long ccu_div_var_calc_divider(unsigned long rate,
 187                                                      unsigned long parent_rate,
 188                                                      unsigned int mask)
 189 {
 190         unsigned long divider;
 191
 192         divider = parent_rate / rate;
 193         return clamp_t(unsigned long, divider, CCU_DIV_CLKDIV_MIN,
 194                        CCU_DIV_CLKDIV_MAX(mask));
 195 }
 196
 197 static long ccu_div_var_round_rate(struct clk_hw *hw, unsigned long rate,
 198                                    unsigned long *parent_rate)
 199 {
 200         struct ccu_div *div = to_ccu_div(hw);
 201         unsigned long divider;
 202
 203         divider = ccu_div_var_calc_divider(rate, *parent_rate, div->mask);
 204
 205         return ccu_div_calc_freq(*parent_rate, divider);
 206 }
 207
 208 /*
 209  * This method is used for the clock divider blocks, which support the
 210  * on-the-fly rate change. So due to lacking the EN bit functionality
 211  * they can't be gated before the rate adjustment.
 212  */
 213 static int ccu_div_var_set_rate_slow(struct clk_hw *hw, unsigned long rate,
 214                                      unsigned long parent_rate)
 215 {
 216         struct ccu_div *div = to_ccu_div(hw);
 217         unsigned long flags, divider;
 218         u32 val;
 219         int ret;
 220
 221         divider = ccu_div_var_calc_divider(rate, parent_rate, div->mask);
 222         if (divider == 1 && div->features & CCU_DIV_SKIP_ONE) {
 223                 divider = 0;
 224         } else if (div->features & CCU_DIV_SKIP_ONE_TO_THREE) {
 225                 if (divider == 1 || divider == 2)
 226                         divider = 0;
 227                 else if (divider == 3)
 228                         divider = 4;
 229         }
 230
 231         val = ccu_div_prep(div->mask, divider);
 232
 233         spin_lock_irqsave(&div->lock, flags);
 234         regmap_update_bits(div->sys_regs, div->reg_ctl, div->mask, val);
 235         ret = ccu_div_var_update_clkdiv(div, parent_rate, divider);
 236         spin_unlock_irqrestore(&div->lock, flags);
 237         if (ret)
 238                 pr_err("Divider '%s' lock timed out\n", clk_hw_get_name(hw));
 239
 240         return ret;
 241 }
 242
 243 /*
 244  * This method is used for the clock divider blocks, which don't support
 245  * the on-the-fly rate change.
 246  */
 247 static int ccu_div_var_set_rate_fast(struct clk_hw *hw, unsigned long rate,
 248                                      unsigned long parent_rate)
 249 {
 250         struct ccu_div *div = to_ccu_div(hw);
 251         unsigned long flags, divider;
 252         u32 val;
 253
 254         divider = ccu_div_var_calc_divider(rate, parent_rate, div->mask);
 255         val = ccu_div_prep(div->mask, divider);
 256
 257         /*
 258          * Also disable the clock divider block if it was enabled by default
 259          * or by the bootloader.
 260          */
 261         spin_lock_irqsave(&div->lock, flags);
 262         regmap_update_bits(div->sys_regs, div->reg_ctl,
 263                            div->mask | CCU_DIV_CTL_EN, val);
 264         spin_unlock_irqrestore(&div->lock, flags);
 265
 266         return 0;
 267 }
 268
 269 static unsigned long ccu_div_fixed_recalc_rate(struct clk_hw *hw,
 270                                                unsigned long parent_rate)
 271 {
 272         struct ccu_div *div = to_ccu_div(hw);
 273
 274         return ccu_div_calc_freq(parent_rate, div->divider);
 275 }
 276
 277 static long ccu_div_fixed_round_rate(struct clk_hw *hw, unsigned long rate,
 278                                      unsigned long *parent_rate)
 279 {
 280         struct ccu_div *div = to_ccu_div(hw);
 281
 282         return ccu_div_calc_freq(*parent_rate, div->divider);
 283 }
 284
 285 static int ccu_div_fixed_set_rate(struct clk_hw *hw, unsigned long rate,
 286                                   unsigned long parent_rate)
 287 {
 288         return 0;
 289 }
 290
 291 int ccu_div_reset_domain(struct ccu_div *div)
 292 {
 293         unsigned long flags;
 294
 295         if (!div || !(div->features & CCU_DIV_RESET_DOMAIN))
 296                 return -EINVAL;
 297
 298         spin_lock_irqsave(&div->lock, flags);
 299         regmap_update_bits(div->sys_regs, div->reg_ctl,
 300                            CCU_DIV_CTL_RST, CCU_DIV_CTL_RST);
 301         spin_unlock_irqrestore(&div->lock, flags);
 302
 303         /* The next delay must be enough to cover all the resets. */
 304         udelay(CCU_DIV_RST_DELAY_US);
 305
 306         return 0;
 307 }
 308
 309 #ifdef CONFIG_DEBUG_FS
 310
 311 struct ccu_div_dbgfs_bit {
 312         struct ccu_div *div;
 313         const char *name;
 314         u32 mask;
 315 };
 316
 317 #define CCU_DIV_DBGFS_BIT_ATTR(_name, _mask) {  \
 318                 .name = _name,                  \
 319                 .mask = _mask                   \
 320         }
 321
 322 static const struct ccu_div_dbgfs_bit ccu_div_bits[] = {
 323         CCU_DIV_DBGFS_BIT_ATTR("div_en", CCU_DIV_CTL_EN),
 324         CCU_DIV_DBGFS_BIT_ATTR("div_rst", CCU_DIV_CTL_RST),
 325         CCU_DIV_DBGFS_BIT_ATTR("div_bypass", CCU_DIV_CTL_SET_CLKDIV),
 326         CCU_DIV_DBGFS_BIT_ATTR("div_lock", CCU_DIV_CTL_LOCK_NORMAL)
 327 };
 328
 329 #define CCU_DIV_DBGFS_BIT_NUM   ARRAY_SIZE(ccu_div_bits)
 330
 331 /*
 332  * It can be dangerous to change the Divider settings behind clock framework
 333  * back, therefore we don't provide any kernel config based compile time option
 334  * for this feature to enable.
 335  */
 336 #undef CCU_DIV_ALLOW_WRITE_DEBUGFS
 337 #ifdef CCU_DIV_ALLOW_WRITE_DEBUGFS
 338
 339 static int ccu_div_dbgfs_bit_set(void *priv, u64 val)
 340 {
 341         const struct ccu_div_dbgfs_bit *bit = priv;
 342         struct ccu_div *div = bit->div;
 343         unsigned long flags;
 344
 345         spin_lock_irqsave(&div->lock, flags);
 346         regmap_update_bits(div->sys_regs, div->reg_ctl,
 347                            bit->mask, val ? bit->mask : 0);
 348         spin_unlock_irqrestore(&div->lock, flags);
 349
 350         return 0;
 351 }
 352
 353 static int ccu_div_dbgfs_var_clkdiv_set(void *priv, u64 val)
 354 {
 355         struct ccu_div *div = priv;
 356         unsigned long flags;
 357         u32 data;
 358
 359         val = clamp_t(u64, val, CCU_DIV_CLKDIV_MIN,
 360                       CCU_DIV_CLKDIV_MAX(div->mask));
 361         data = ccu_div_prep(div->mask, val);
 362
 363         spin_lock_irqsave(&div->lock, flags);
 364         regmap_update_bits(div->sys_regs, div->reg_ctl, div->mask, data);
 365         spin_unlock_irqrestore(&div->lock, flags);
 366
 367         return 0;
 368 }
 369
 370 #define ccu_div_dbgfs_mode              0644
 371
 372 #else /* !CCU_DIV_ALLOW_WRITE_DEBUGFS */
 373
 374 #define ccu_div_dbgfs_bit_set           NULL
 375 #define ccu_div_dbgfs_var_clkdiv_set    NULL
 376 #define ccu_div_dbgfs_mode              0444
 377
 378 #endif /* !CCU_DIV_ALLOW_WRITE_DEBUGFS */
 379
 380 static int ccu_div_dbgfs_bit_get(void *priv, u64 *val)
 381 {
 382         const struct ccu_div_dbgfs_bit *bit = priv;
 383         struct ccu_div *div = bit->div;
 384         u32 data = 0;
 385
 386         regmap_read(div->sys_regs, div->reg_ctl, &data);
 387         *val = !!(data & bit->mask);
 388
 389         return 0;
 390 }
 391 DEFINE_DEBUGFS_ATTRIBUTE(ccu_div_dbgfs_bit_fops,
 392         ccu_div_dbgfs_bit_get, ccu_div_dbgfs_bit_set, "%llu\n");
 393
 394 static int ccu_div_dbgfs_var_clkdiv_get(void *priv, u64 *val)
 395 {
 396         struct ccu_div *div = priv;
 397         u32 data = 0;
 398
 399         regmap_read(div->sys_regs, div->reg_ctl, &data);
 400         *val = ccu_div_get(div->mask, data);
 401
 402         return 0;
 403 }
 404 DEFINE_DEBUGFS_ATTRIBUTE(ccu_div_dbgfs_var_clkdiv_fops,
 405         ccu_div_dbgfs_var_clkdiv_get, ccu_div_dbgfs_var_clkdiv_set, "%llu\n");
 406
 407 static int ccu_div_dbgfs_fixed_clkdiv_get(void *priv, u64 *val)
 408 {
 409         struct ccu_div *div = priv;
 410
 411         *val = div->divider;
 412
 413         return 0;
 414 }
 415 DEFINE_DEBUGFS_ATTRIBUTE(ccu_div_dbgfs_fixed_clkdiv_fops,
 416         ccu_div_dbgfs_fixed_clkdiv_get, NULL, "%llu\n");
 417
 418 static void ccu_div_var_debug_init(struct clk_hw *hw, struct dentry *dentry)
 419 {
 420         struct ccu_div *div = to_ccu_div(hw);
 421         struct ccu_div_dbgfs_bit *bits;
 422         int didx, bidx, num = 2;
 423         const char *name;
 424
 425         num += !!(div->flags & CLK_SET_RATE_GATE) +
 426                 !!(div->features & CCU_DIV_RESET_DOMAIN);
 427
 428         bits = kcalloc(num, sizeof(*bits), GFP_KERNEL);
 429         if (!bits)
 430                 return;
 431
 432         for (didx = 0, bidx = 0; bidx < CCU_DIV_DBGFS_BIT_NUM; ++bidx) {
 433                 name = ccu_div_bits[bidx].name;
 434                 if (!(div->flags & CLK_SET_RATE_GATE) &&
 435                     !strcmp("div_en", name)) {
 436                         continue;
 437                 }
 438
 439                 if (!(div->features & CCU_DIV_RESET_DOMAIN) &&
 440                     !strcmp("div_rst", name)) {
 441                         continue;
 442                 }
 443
 444                 bits[didx] = ccu_div_bits[bidx];
 445                 bits[didx].div = div;
 446
 447                 if (div->features & CCU_DIV_LOCK_SHIFTED &&
 448                     !strcmp("div_lock", name)) {
 449                         bits[didx].mask = CCU_DIV_CTL_LOCK_SHIFTED;
 450                 }
 451
 452                 debugfs_create_file_unsafe(bits[didx].name, ccu_div_dbgfs_mode,
 453                                            dentry, &bits[didx],
 454                                            &ccu_div_dbgfs_bit_fops);
 455                 ++didx;
 456         }
 457
 458         debugfs_create_file_unsafe("div_clkdiv", ccu_div_dbgfs_mode, dentry,
 459                                    div, &ccu_div_dbgfs_var_clkdiv_fops);
 460 }
 461
 462 static void ccu_div_gate_debug_init(struct clk_hw *hw, struct dentry *dentry)
 463 {
 464         struct ccu_div *div = to_ccu_div(hw);
 465         struct ccu_div_dbgfs_bit *bit;
 466
 467         bit = kmalloc(sizeof(*bit), GFP_KERNEL);
 468         if (!bit)
 469                 return;
 470
 471         *bit = ccu_div_bits[0];
 472         bit->div = div;
 473         debugfs_create_file_unsafe(bit->name, ccu_div_dbgfs_mode, dentry, bit,
 474                                    &ccu_div_dbgfs_bit_fops);
 475
 476         debugfs_create_file_unsafe("div_clkdiv", 0400, dentry, div,
 477                                    &ccu_div_dbgfs_fixed_clkdiv_fops);
 478 }
 479
 480 static void ccu_div_fixed_debug_init(struct clk_hw *hw, struct dentry *dentry)
 481 {
 482         struct ccu_div *div = to_ccu_div(hw);
 483
 484         debugfs_create_file_unsafe("div_clkdiv", 0400, dentry, div,
 485                                    &ccu_div_dbgfs_fixed_clkdiv_fops);
 486 }
 487
 488 #else /* !CONFIG_DEBUG_FS */
 489
 490 #define ccu_div_var_debug_init NULL
 491 #define ccu_div_gate_debug_init NULL
 492 #define ccu_div_fixed_debug_init NULL
 493
 494 #endif /* !CONFIG_DEBUG_FS */
 495
 496 static const struct clk_ops ccu_div_var_gate_to_set_ops = {
 497         .enable = ccu_div_var_enable,
 498         .disable = ccu_div_gate_disable,
 499         .is_enabled = ccu_div_gate_is_enabled,
 500         .recalc_rate = ccu_div_var_recalc_rate,
 501         .round_rate = ccu_div_var_round_rate,
 502         .set_rate = ccu_div_var_set_rate_fast,
 503         .debug_init = ccu_div_var_debug_init
 504 };
 505
 506 static const struct clk_ops ccu_div_var_nogate_ops = {
 507         .recalc_rate = ccu_div_var_recalc_rate,
 508         .round_rate = ccu_div_var_round_rate,
 509         .set_rate = ccu_div_var_set_rate_slow,
 510         .debug_init = ccu_div_var_debug_init
 511 };
 512
 513 static const struct clk_ops ccu_div_gate_ops = {
 514         .enable = ccu_div_gate_enable,
 515         .disable = ccu_div_gate_disable,
 516         .is_enabled = ccu_div_gate_is_enabled,
 517         .recalc_rate = ccu_div_fixed_recalc_rate,
 518         .round_rate = ccu_div_fixed_round_rate,
 519         .set_rate = ccu_div_fixed_set_rate,
 520         .debug_init = ccu_div_gate_debug_init
 521 };
 522
 523 static const struct clk_ops ccu_div_fixed_ops = {
 524         .recalc_rate = ccu_div_fixed_recalc_rate,
 525         .round_rate = ccu_div_fixed_round_rate,
 526         .set_rate = ccu_div_fixed_set_rate,
 527         .debug_init = ccu_div_fixed_debug_init
 528 };
 529
 530 struct ccu_div *ccu_div_hw_register(const struct ccu_div_init_data *div_init)
 531 {
 532         struct clk_parent_data parent_data = { };
 533         struct clk_init_data hw_init = { };
 534         struct ccu_div *div;
 535         int ret;
 536
 537         if (!div_init)
 538                 return ERR_PTR(-EINVAL);
 539
 540         div = kzalloc(sizeof(*div), GFP_KERNEL);
 541         if (!div)
 542                 return ERR_PTR(-ENOMEM);
 543
 544         /*
 545          * Note since Baikal-T1 System Controller registers are MMIO-backed
 546          * we won't check the regmap IO operations return status, because it
 547          * must be zero anyway.
 548          */
 549         div->hw.init = &hw_init;
 550         div->id = div_init->id;
 551         div->reg_ctl = div_init->base + CCU_DIV_CTL;
 552         div->sys_regs = div_init->sys_regs;
 553         div->flags = div_init->flags;
 554         div->features = div_init->features;
 555         spin_lock_init(&div->lock);
 556
 557         hw_init.name = div_init->name;
 558         hw_init.flags = div_init->flags;
 559
 560         if (div_init->type == CCU_DIV_VAR) {
 561                 if (hw_init.flags & CLK_SET_RATE_GATE)
 562                         hw_init.ops = &ccu_div_var_gate_to_set_ops;
 563                 else
 564                         hw_init.ops = &ccu_div_var_nogate_ops;
 565                 div->mask = CCU_DIV_CTL_CLKDIV_MASK(div_init->width);
 566         } else if (div_init->type == CCU_DIV_GATE) {
 567                 hw_init.ops = &ccu_div_gate_ops;
 568                 div->divider = div_init->divider;
 569         } else if (div_init->type == CCU_DIV_FIXED) {
 570                 hw_init.ops = &ccu_div_fixed_ops;
 571                 div->divider = div_init->divider;
 572         } else {
 573                 ret = -EINVAL;
 574                 goto err_free_div;
 575         }
 576
 577         if (!div_init->parent_name) {
 578                 ret = -EINVAL;
 579                 goto err_free_div;
 580         }
 581         parent_data.fw_name = div_init->parent_name;
 582         hw_init.parent_data = &parent_data;
 583         hw_init.num_parents = 1;
 584
 585         ret = of_clk_hw_register(div_init->np, &div->hw);
 586         if (ret)
 587                 goto err_free_div;
 588
 589         return div;
 590
 591 err_free_div:
 592         kfree(div);
 593
 594         return ERR_PTR(ret);
 595 }
 596
 597 void ccu_div_hw_unregister(struct ccu_div *div)
 598 {
 599         clk_hw_unregister(&div->hw);
 600
 601         kfree(div);
 602 }