drivers/clk/rockchip/clk.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) 2014 MundoReader S.L.
   4  * Author: Heiko Stuebner <[email protected]>
   5  *
   6  * Copyright (c) 2016 Rockchip Electronics Co. Ltd.
   7  * Author: Xing Zheng <[email protected]>
   8  *
   9  * based on
  10  *
  11  * samsung/clk.c
  12  * Copyright (c) 2013 Samsung Electronics Co., Ltd.
  13  * Copyright (c) 2013 Linaro Ltd.
  14  * Author: Thomas Abraham <[email protected]>
  15  */
  16
  17 #include <linux/slab.h>
  18 #include <linux/clk.h>
  19 #include <linux/clk-provider.h>
  20 #include <linux/io.h>
  21 #include <linux/mfd/syscon.h>
  22 #include <linux/regmap.h>
  23 #include <linux/reboot.h>
  24 #include <linux/rational.h>
  25
  26 #include "../clk-fractional-divider.h"
  27 #include "clk.h"
  28
  29 /*
  30  * Register a clock branch.
  31  * Most clock branches have a form like
  32  *
  33  * src1 --|--\
  34  *        |M |--[GATE]-[DIV]-
  35  * src2 --|--/
  36  *
  37  * sometimes without one of those components.
  38  */
  39 static struct clk *rockchip_clk_register_branch(const char *name,
  40                 const char *const *parent_names, u8 num_parents,
  41                 void __iomem *base,
  42                 int muxdiv_offset, u8 mux_shift, u8 mux_width, u8 mux_flags,
  43                 int div_offset, u8 div_shift, u8 div_width, u8 div_flags,
  44                 struct clk_div_table *div_table, int gate_offset,
  45                 u8 gate_shift, u8 gate_flags, unsigned long flags,
  46                 spinlock_t *lock)
  47 {
  48         struct clk_hw *hw;
  49         struct clk_mux *mux = NULL;
  50         struct clk_gate *gate = NULL;
  51         struct clk_divider *div = NULL;
  52         const struct clk_ops *mux_ops = NULL, *div_ops = NULL,
  53                              *gate_ops = NULL;
  54         int ret;
  55
  56         if (num_parents > 1) {
  57                 mux = kzalloc(sizeof(*mux), GFP_KERNEL);
  58                 if (!mux)
  59                         return ERR_PTR(-ENOMEM);
  60
  61                 mux->reg = base + muxdiv_offset;
  62                 mux->shift = mux_shift;
  63                 mux->mask = BIT(mux_width) - 1;
  64                 mux->flags = mux_flags;
  65                 mux->lock = lock;
  66                 mux_ops = (mux_flags & CLK_MUX_READ_ONLY) ? &clk_mux_ro_ops
  67                                                         : &clk_mux_ops;
  68         }
  69
  70         if (gate_offset >= 0) {
  71                 gate = kzalloc(sizeof(*gate), GFP_KERNEL);
  72                 if (!gate) {
  73                         ret = -ENOMEM;
  74                         goto err_gate;
  75                 }
  76
  77                 gate->flags = gate_flags;
  78                 gate->reg = base + gate_offset;
  79                 gate->bit_idx = gate_shift;
  80                 gate->lock = lock;
  81                 gate_ops = &clk_gate_ops;
  82         }
  83
  84         if (div_width > 0) {
  85                 div = kzalloc(sizeof(*div), GFP_KERNEL);
  86                 if (!div) {
  87                         ret = -ENOMEM;
  88                         goto err_div;
  89                 }
  90
  91                 div->flags = div_flags;
  92                 if (div_offset)
  93                         div->reg = base + div_offset;
  94                 else
  95                         div->reg = base + muxdiv_offset;
  96                 div->shift = div_shift;
  97                 div->width = div_width;
  98                 div->lock = lock;
  99                 div->table = div_table;
 100                 div_ops = (div_flags & CLK_DIVIDER_READ_ONLY)
 101                                                 ? &clk_divider_ro_ops
 102                                                 : &clk_divider_ops;
 103         }
 104
 105         hw = clk_hw_register_composite(NULL, name, parent_names, num_parents,
 106                                        mux ? &mux->hw : NULL, mux_ops,
 107                                        div ? &div->hw : NULL, div_ops,
 108                                        gate ? &gate->hw : NULL, gate_ops,
 109                                        flags);
 110         if (IS_ERR(hw)) {
 111                 kfree(div);
 112                 kfree(gate);
 113                 return ERR_CAST(hw);
 114         }
 115
 116         return hw->clk;
 117 err_div:
 118         kfree(gate);
 119 err_gate:
 120         kfree(mux);
 121         return ERR_PTR(ret);
 122 }
 123
 124 struct rockchip_clk_frac {
 125         struct notifier_block                   clk_nb;
 126         struct clk_fractional_divider           div;
 127         struct clk_gate                         gate;
 128
 129         struct clk_mux                          mux;
 130         const struct clk_ops                    *mux_ops;
 131         int                                     mux_frac_idx;
 132
 133         bool                                    rate_change_remuxed;
 134         int                                     rate_change_idx;
 135 };
 136
 137 #define to_rockchip_clk_frac_nb(nb) \
 138                         container_of(nb, struct rockchip_clk_frac, clk_nb)
 139
 140 static int rockchip_clk_frac_notifier_cb(struct notifier_block *nb,
 141                                          unsigned long event, void *data)
 142 {
 143         struct clk_notifier_data *ndata = data;
 144         struct rockchip_clk_frac *frac = to_rockchip_clk_frac_nb(nb);
 145         struct clk_mux *frac_mux = &frac->mux;
 146         int ret = 0;
 147
 148         pr_debug("%s: event %lu, old_rate %lu, new_rate: %lu\n",
 149                  __func__, event, ndata->old_rate, ndata->new_rate);
 150         if (event == PRE_RATE_CHANGE) {
 151                 frac->rate_change_idx =
 152                                 frac->mux_ops->get_parent(&frac_mux->hw);
 153                 if (frac->rate_change_idx != frac->mux_frac_idx) {
 154                         frac->mux_ops->set_parent(&frac_mux->hw,
 155                                                   frac->mux_frac_idx);
 156                         frac->rate_change_remuxed = 1;
 157                 }
 158         } else if (event == POST_RATE_CHANGE) {
 159                 /*
 160                  * The POST_RATE_CHANGE notifier runs directly after the
 161                  * divider clock is set in clk_change_rate, so we'll have
 162                  * remuxed back to the original parent before clk_change_rate
 163                  * reaches the mux itself.
 164                  */
 165                 if (frac->rate_change_remuxed) {
 166                         frac->mux_ops->set_parent(&frac_mux->hw,
 167                                                   frac->rate_change_idx);
 168                         frac->rate_change_remuxed = 0;
 169                 }
 170         }
 171
 172         return notifier_from_errno(ret);
 173 }
 174
 175 /*
 176  * fractional divider must set that denominator is 20 times larger than
 177  * numerator to generate precise clock frequency.
 178  */
 179 static void rockchip_fractional_approximation(struct clk_hw *hw,
 180                 unsigned long rate, unsigned long *parent_rate,
 181                 unsigned long *m, unsigned long *n)
 182 {
 183         unsigned long p_rate, p_parent_rate;
 184         struct clk_hw *p_parent;
 185
 186         p_rate = clk_hw_get_rate(clk_hw_get_parent(hw));
 187         if ((rate * 20 > p_rate) && (p_rate % rate != 0)) {
 188                 p_parent = clk_hw_get_parent(clk_hw_get_parent(hw));
 189                 p_parent_rate = clk_hw_get_rate(p_parent);
 190                 *parent_rate = p_parent_rate;
 191         }
 192
 193         clk_fractional_divider_general_approximation(hw, rate, parent_rate, m, n);
 194 }
 195
 196 static struct clk *rockchip_clk_register_frac_branch(
 197                 struct rockchip_clk_provider *ctx, const char *name,
 198                 const char *const *parent_names, u8 num_parents,
 199                 void __iomem *base, int muxdiv_offset, u8 div_flags,
 200                 int gate_offset, u8 gate_shift, u8 gate_flags,
 201                 unsigned long flags, struct rockchip_clk_branch *child,
 202                 spinlock_t *lock)
 203 {
 204         struct clk_hw *hw;
 205         struct rockchip_clk_frac *frac;
 206         struct clk_gate *gate = NULL;
 207         struct clk_fractional_divider *div = NULL;
 208         const struct clk_ops *div_ops = NULL, *gate_ops = NULL;
 209
 210         if (muxdiv_offset < 0)
 211                 return ERR_PTR(-EINVAL);
 212
 213         if (child && child->branch_type != branch_mux) {
 214                 pr_err("%s: fractional child clock for %s can only be a mux\n",
 215                        __func__, name);
 216                 return ERR_PTR(-EINVAL);
 217         }
 218
 219         frac = kzalloc(sizeof(*frac), GFP_KERNEL);
 220         if (!frac)
 221                 return ERR_PTR(-ENOMEM);
 222
 223         if (gate_offset >= 0) {
 224                 gate = &frac->gate;
 225                 gate->flags = gate_flags;
 226                 gate->reg = base + gate_offset;
 227                 gate->bit_idx = gate_shift;
 228                 gate->lock = lock;
 229                 gate_ops = &clk_gate_ops;
 230         }
 231
 232         div = &frac->div;
 233         div->flags = div_flags;
 234         div->reg = base + muxdiv_offset;
 235         div->mshift = 16;
 236         div->mwidth = 16;
 237         div->mmask = GENMASK(div->mwidth - 1, 0) << div->mshift;
 238         div->nshift = 0;
 239         div->nwidth = 16;
 240         div->nmask = GENMASK(div->nwidth - 1, 0) << div->nshift;
 241         div->lock = lock;
 242         div->approximation = rockchip_fractional_approximation;
 243         div_ops = &clk_fractional_divider_ops;
 244
 245         hw = clk_hw_register_composite(NULL, name, parent_names, num_parents,
 246                                        NULL, NULL,
 247                                        &div->hw, div_ops,
 248                                        gate ? &gate->hw : NULL, gate_ops,
 249                                        flags | CLK_SET_RATE_UNGATE);
 250         if (IS_ERR(hw)) {
 251                 kfree(frac);
 252                 return ERR_CAST(hw);
 253         }
 254
 255         if (child) {
 256                 struct clk_mux *frac_mux = &frac->mux;
 257                 struct clk_init_data init;
 258                 struct clk *mux_clk;
 259                 int ret;
 260
 261                 frac->mux_frac_idx = match_string(child->parent_names,
 262                                                   child->num_parents, name);
 263                 frac->mux_ops = &clk_mux_ops;
 264                 frac->clk_nb.notifier_call = rockchip_clk_frac_notifier_cb;
 265
 266                 frac_mux->reg = base + child->muxdiv_offset;
 267                 frac_mux->shift = child->mux_shift;
 268                 frac_mux->mask = BIT(child->mux_width) - 1;
 269                 frac_mux->flags = child->mux_flags;
 270                 frac_mux->lock = lock;
 271                 frac_mux->hw.init = &init;
 272
 273                 init.name = child->name;
 274                 init.flags = child->flags | CLK_SET_RATE_PARENT;
 275                 init.ops = frac->mux_ops;
 276                 init.parent_names = child->parent_names;
 277                 init.num_parents = child->num_parents;
 278
 279                 mux_clk = clk_register(NULL, &frac_mux->hw);
 280                 if (IS_ERR(mux_clk)) {
 281                         kfree(frac);
 282                         return mux_clk;
 283                 }
 284
 285                 rockchip_clk_add_lookup(ctx, mux_clk, child->id);
 286
 287                 /* notifier on the fraction divider to catch rate changes */
 288                 if (frac->mux_frac_idx >= 0) {
 289                         pr_debug("%s: found fractional parent in mux at pos %d\n",
 290                                  __func__, frac->mux_frac_idx);
 291                         ret = clk_notifier_register(hw->clk, &frac->clk_nb);
 292                         if (ret)
 293                                 pr_err("%s: failed to register clock notifier for %s\n",
 294                                                 __func__, name);
 295                 } else {
 296                         pr_warn("%s: could not find %s as parent of %s, rate changes may not work\n",
 297                                 __func__, name, child->name);
 298                 }
 299         }
 300
 301         return hw->clk;
 302 }
 303
 304 static struct clk *rockchip_clk_register_factor_branch(const char *name,
 305                 const char *const *parent_names, u8 num_parents,
 306                 void __iomem *base, unsigned int mult, unsigned int div,
 307                 int gate_offset, u8 gate_shift, u8 gate_flags,
 308                 unsigned long flags, spinlock_t *lock)
 309 {
 310         struct clk_hw *hw;
 311         struct clk_gate *gate = NULL;
 312         struct clk_fixed_factor *fix = NULL;
 313
 314         /* without gate, register a simple factor clock */
 315         if (gate_offset == 0) {
 316                 return clk_register_fixed_factor(NULL, name,
 317                                 parent_names[0], flags, mult,
 318                                 div);
 319         }
 320
 321         gate = kzalloc(sizeof(*gate), GFP_KERNEL);
 322         if (!gate)
 323                 return ERR_PTR(-ENOMEM);
 324
 325         gate->flags = gate_flags;
 326         gate->reg = base + gate_offset;
 327         gate->bit_idx = gate_shift;
 328         gate->lock = lock;
 329
 330         fix = kzalloc(sizeof(*fix), GFP_KERNEL);
 331         if (!fix) {
 332                 kfree(gate);
 333                 return ERR_PTR(-ENOMEM);
 334         }
 335
 336         fix->mult = mult;
 337         fix->div = div;
 338
 339         hw = clk_hw_register_composite(NULL, name, parent_names, num_parents,
 340                                        NULL, NULL,
 341                                        &fix->hw, &clk_fixed_factor_ops,
 342                                        &gate->hw, &clk_gate_ops, flags);
 343         if (IS_ERR(hw)) {
 344                 kfree(fix);
 345                 kfree(gate);
 346                 return ERR_CAST(hw);
 347         }
 348
 349         return hw->clk;
 350 }
 351
 352 struct rockchip_clk_provider *rockchip_clk_init(struct device_node *np,
 353                                                 void __iomem *base,
 354                                                 unsigned long nr_clks)
 355 {
 356         struct rockchip_clk_provider *ctx;
 357         struct clk **clk_table;
 358         int i;
 359
 360         ctx = kzalloc(sizeof(struct rockchip_clk_provider), GFP_KERNEL);
 361         if (!ctx)
 362                 return ERR_PTR(-ENOMEM);
 363
 364         clk_table = kcalloc(nr_clks, sizeof(struct clk *), GFP_KERNEL);
 365         if (!clk_table)
 366                 goto err_free;
 367
 368         for (i = 0; i < nr_clks; ++i)
 369                 clk_table[i] = ERR_PTR(-ENOENT);
 370
 371         ctx->reg_base = base;
 372         ctx->clk_data.clks = clk_table;
 373         ctx->clk_data.clk_num = nr_clks;
 374         ctx->cru_node = np;
 375         spin_lock_init(&ctx->lock);
 376
 377         ctx->grf = syscon_regmap_lookup_by_phandle(ctx->cru_node,
 378                                                    "rockchip,grf");
 379
 380         return ctx;
 381
 382 err_free:
 383         kfree(ctx);
 384         return ERR_PTR(-ENOMEM);
 385 }
 386 EXPORT_SYMBOL_GPL(rockchip_clk_init);
 387
 388 void rockchip_clk_of_add_provider(struct device_node *np,
 389                                   struct rockchip_clk_provider *ctx)
 390 {
 391         if (of_clk_add_provider(np, of_clk_src_onecell_get,
 392                                 &ctx->clk_data))
 393                 pr_err("%s: could not register clk provider\n", __func__);
 394 }
 395 EXPORT_SYMBOL_GPL(rockchip_clk_of_add_provider);
 396
 397 void rockchip_clk_add_lookup(struct rockchip_clk_provider *ctx,
 398                              struct clk *clk, unsigned int id)
 399 {
 400         if (ctx->clk_data.clks && id)
 401                 ctx->clk_data.clks[id] = clk;
 402 }
 403 EXPORT_SYMBOL_GPL(rockchip_clk_add_lookup);
 404
 405 void rockchip_clk_register_plls(struct rockchip_clk_provider *ctx,
 406                                 struct rockchip_pll_clock *list,
 407                                 unsigned int nr_pll, int grf_lock_offset)
 408 {
 409         struct clk *clk;
 410         int idx;
 411
 412         for (idx = 0; idx < nr_pll; idx++, list++) {
 413                 clk = rockchip_clk_register_pll(ctx, list->type, list->name,
 414                                 list->parent_names, list->num_parents,
 415                                 list->con_offset, grf_lock_offset,
 416                                 list->lock_shift, list->mode_offset,
 417                                 list->mode_shift, list->rate_table,
 418                                 list->flags, list->pll_flags);
 419                 if (IS_ERR(clk)) {
 420                         pr_err("%s: failed to register clock %s\n", __func__,
 421                                 list->name);
 422                         continue;
 423                 }
 424
 425                 rockchip_clk_add_lookup(ctx, clk, list->id);
 426         }
 427 }
 428 EXPORT_SYMBOL_GPL(rockchip_clk_register_plls);
 429
 430 void rockchip_clk_register_branches(struct rockchip_clk_provider *ctx,
 431                                     struct rockchip_clk_branch *list,
 432                                     unsigned int nr_clk)
 433 {
 434         struct clk *clk = NULL;
 435         unsigned int idx;
 436         unsigned long flags;
 437
 438         for (idx = 0; idx < nr_clk; idx++, list++) {
 439                 flags = list->flags;
 440
 441                 /* catch simple muxes */
 442                 switch (list->branch_type) {
 443                 case branch_mux:
 444                         clk = clk_register_mux(NULL, list->name,
 445                                 list->parent_names, list->num_parents,
 446                                 flags, ctx->reg_base + list->muxdiv_offset,
 447                                 list->mux_shift, list->mux_width,
 448                                 list->mux_flags, &ctx->lock);
 449                         break;
 450                 case branch_muxgrf:
 451                         clk = rockchip_clk_register_muxgrf(list->name,
 452                                 list->parent_names, list->num_parents,
 453                                 flags, ctx->grf, list->muxdiv_offset,
 454                                 list->mux_shift, list->mux_width,
 455                                 list->mux_flags);
 456                         break;
 457                 case branch_divider:
 458                         if (list->div_table)
 459                                 clk = clk_register_divider_table(NULL,
 460                                         list->name, list->parent_names[0],
 461                                         flags,
 462                                         ctx->reg_base + list->muxdiv_offset,
 463                                         list->div_shift, list->div_width,
 464                                         list->div_flags, list->div_table,
 465                                         &ctx->lock);
 466                         else
 467                                 clk = clk_register_divider(NULL, list->name,
 468                                         list->parent_names[0], flags,
 469                                         ctx->reg_base + list->muxdiv_offset,
 470                                         list->div_shift, list->div_width,
 471                                         list->div_flags, &ctx->lock);
 472                         break;
 473                 case branch_fraction_divider:
 474                         clk = rockchip_clk_register_frac_branch(ctx, list->name,
 475                                 list->parent_names, list->num_parents,
 476                                 ctx->reg_base, list->muxdiv_offset,
 477                                 list->div_flags,
 478                                 list->gate_offset, list->gate_shift,
 479                                 list->gate_flags, flags, list->child,
 480                                 &ctx->lock);
 481                         break;
 482                 case branch_half_divider:
 483                         clk = rockchip_clk_register_halfdiv(list->name,
 484                                 list->parent_names, list->num_parents,
 485                                 ctx->reg_base, list->muxdiv_offset,
 486                                 list->mux_shift, list->mux_width,
 487                                 list->mux_flags, list->div_shift,
 488                                 list->div_width, list->div_flags,
 489                                 list->gate_offset, list->gate_shift,
 490                                 list->gate_flags, flags, &ctx->lock);
 491                         break;
 492                 case branch_gate:
 493                         flags |= CLK_SET_RATE_PARENT;
 494
 495                         clk = clk_register_gate(NULL, list->name,
 496                                 list->parent_names[0], flags,
 497                                 ctx->reg_base + list->gate_offset,
 498                                 list->gate_shift, list->gate_flags, &ctx->lock);
 499                         break;
 500                 case branch_composite:
 501                         clk = rockchip_clk_register_branch(list->name,
 502                                 list->parent_names, list->num_parents,
 503                                 ctx->reg_base, list->muxdiv_offset,
 504                                 list->mux_shift,
 505                                 list->mux_width, list->mux_flags,
 506                                 list->div_offset, list->div_shift, list->div_width,
 507                                 list->div_flags, list->div_table,
 508                                 list->gate_offset, list->gate_shift,
 509                                 list->gate_flags, flags, &ctx->lock);
 510                         break;
 511                 case branch_mmc:
 512                         clk = rockchip_clk_register_mmc(
 513                                 list->name,
 514                                 list->parent_names, list->num_parents,
 515                                 ctx->reg_base + list->muxdiv_offset,
 516                                 list->div_shift
 517                         );
 518                         break;
 519                 case branch_inverter:
 520                         clk = rockchip_clk_register_inverter(
 521                                 list->name, list->parent_names,
 522                                 list->num_parents,
 523                                 ctx->reg_base + list->muxdiv_offset,
 524                                 list->div_shift, list->div_flags, &ctx->lock);
 525                         break;
 526                 case branch_factor:
 527                         clk = rockchip_clk_register_factor_branch(
 528                                 list->name, list->parent_names,
 529                                 list->num_parents, ctx->reg_base,
 530                                 list->div_shift, list->div_width,
 531                                 list->gate_offset, list->gate_shift,
 532                                 list->gate_flags, flags, &ctx->lock);
 533                         break;
 534                 case branch_ddrclk:
 535                         clk = rockchip_clk_register_ddrclk(
 536                                 list->name, list->flags,
 537                                 list->parent_names, list->num_parents,
 538                                 list->muxdiv_offset, list->mux_shift,
 539                                 list->mux_width, list->div_shift,
 540                                 list->div_width, list->div_flags,
 541                                 ctx->reg_base, &ctx->lock);
 542                         break;
 543                 }
 544
 545                 /* none of the cases above matched */
 546                 if (!clk) {
 547                         pr_err("%s: unknown clock type %d\n",
 548                                __func__, list->branch_type);
 549                         continue;
 550                 }
 551
 552                 if (IS_ERR(clk)) {
 553                         pr_err("%s: failed to register clock %s: %ld\n",
 554                                __func__, list->name, PTR_ERR(clk));
 555                         continue;
 556                 }
 557
 558                 rockchip_clk_add_lookup(ctx, clk, list->id);
 559         }
 560 }
 561 EXPORT_SYMBOL_GPL(rockchip_clk_register_branches);
 562
 563 void rockchip_clk_register_armclk(struct rockchip_clk_provider *ctx,
 564                                   unsigned int lookup_id,
 565                                   const char *name, const char *const *parent_names,
 566                                   u8 num_parents,
 567                                   const struct rockchip_cpuclk_reg_data *reg_data,
 568                                   const struct rockchip_cpuclk_rate_table *rates,
 569                                   int nrates)
 570 {
 571         struct clk *clk;
 572
 573         clk = rockchip_clk_register_cpuclk(name, parent_names, num_parents,
 574                                            reg_data, rates, nrates,
 575                                            ctx->reg_base, &ctx->lock);
 576         if (IS_ERR(clk)) {
 577                 pr_err("%s: failed to register clock %s: %ld\n",
 578                        __func__, name, PTR_ERR(clk));
 579                 return;
 580         }
 581
 582         rockchip_clk_add_lookup(ctx, clk, lookup_id);
 583 }
 584 EXPORT_SYMBOL_GPL(rockchip_clk_register_armclk);
 585
 586 void rockchip_clk_protect_critical(const char *const clocks[],
 587                                    int nclocks)
 588 {
 589         int i;
 590
 591         /* Protect the clocks that needs to stay on */
 592         for (i = 0; i < nclocks; i++) {
 593                 struct clk *clk = __clk_lookup(clocks[i]);
 594
 595                 clk_prepare_enable(clk);
 596         }
 597 }
 598 EXPORT_SYMBOL_GPL(rockchip_clk_protect_critical);
 599
 600 static void __iomem *rst_base;
 601 static unsigned int reg_restart;
 602 static void (*cb_restart)(void);
 603 static int rockchip_restart_notify(struct notifier_block *this,
 604                                    unsigned long mode, void *cmd)
 605 {
 606         if (cb_restart)
 607                 cb_restart();
 608
 609         writel(0xfdb9, rst_base + reg_restart);
 610         return NOTIFY_DONE;
 611 }
 612
 613 static struct notifier_block rockchip_restart_handler = {
 614         .notifier_call = rockchip_restart_notify,
 615         .priority = 128,
 616 };
 617
 618 void
 619 rockchip_register_restart_notifier(struct rockchip_clk_provider *ctx,
 620                                    unsigned int reg,
 621                                    void (*cb)(void))
 622 {
 623         int ret;
 624
 625         rst_base = ctx->reg_base;
 626         reg_restart = reg;
 627         cb_restart = cb;
 628         ret = register_restart_handler(&rockchip_restart_handler);
 629         if (ret)
 630                 pr_err("%s: cannot register restart handler, %d\n",
 631                        __func__, ret);
 632 }
 633 EXPORT_SYMBOL_GPL(rockchip_register_restart_notifier);