drivers/clk/at91/clk-generated.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Copyright (C) 2015 Atmel Corporation,
   4  *                     Nicolas Ferre <nicolas.ferre@atmel.com>
   5  *
   6  * Based on clk-programmable & clk-peripheral drivers by Boris BREZILLON.
   7  */
   8
   9 #include <linux/bitfield.h>
  10 #include <linux/clk-provider.h>
  11 #include <linux/clkdev.h>
  12 #include <linux/clk/at91_pmc.h>
  13 #include <linux/of.h>
  14 #include <linux/mfd/syscon.h>
  15 #include <linux/regmap.h>
  16
  17 #include "pmc.h"
  18
  19 #define GENERATED_MAX_DIV       255
  20
  21 #define GCK_INDEX_DT_AUDIO_PLL  5
  22
  23 struct clk_generated {
  24         struct clk_hw hw;
  25         struct regmap *regmap;
  26         struct clk_range range;
  27         spinlock_t *lock;
  28         u32 id;
  29         u32 gckdiv;
  30         const struct clk_pcr_layout *layout;
  31         u8 parent_id;
  32         bool audio_pll_allowed;
  33 };
  34
  35 #define to_clk_generated(hw) \
  36         container_of(hw, struct clk_generated, hw)
  37
  38 static int clk_generated_enable(struct clk_hw *hw)
  39 {
  40         struct clk_generated *gck = to_clk_generated(hw);
  41         unsigned long flags;
  42
  43         pr_debug("GCLK: %s, gckdiv = %d, parent id = %d\n",
  44                  __func__, gck->gckdiv, gck->parent_id);
  45
  46         spin_lock_irqsave(gck->lock, flags);
  47         regmap_write(gck->regmap, gck->layout->offset,
  48                      (gck->id & gck->layout->pid_mask));
  49         regmap_update_bits(gck->regmap, gck->layout->offset,
  50                            AT91_PMC_PCR_GCKDIV_MASK | gck->layout->gckcss_mask |
  51                            gck->layout->cmd | AT91_PMC_PCR_GCKEN,
  52                            field_prep(gck->layout->gckcss_mask, gck->parent_id) |
  53                            gck->layout->cmd |
  54                            FIELD_PREP(AT91_PMC_PCR_GCKDIV_MASK, gck->gckdiv) |
  55                            AT91_PMC_PCR_GCKEN);
  56         spin_unlock_irqrestore(gck->lock, flags);
  57         return 0;
  58 }
  59
  60 static void clk_generated_disable(struct clk_hw *hw)
  61 {
  62         struct clk_generated *gck = to_clk_generated(hw);
  63         unsigned long flags;
  64
  65         spin_lock_irqsave(gck->lock, flags);
  66         regmap_write(gck->regmap, gck->layout->offset,
  67                      (gck->id & gck->layout->pid_mask));
  68         regmap_update_bits(gck->regmap, gck->layout->offset,
  69                            gck->layout->cmd | AT91_PMC_PCR_GCKEN,
  70                            gck->layout->cmd);
  71         spin_unlock_irqrestore(gck->lock, flags);
  72 }
  73
  74 static int clk_generated_is_enabled(struct clk_hw *hw)
  75 {
  76         struct clk_generated *gck = to_clk_generated(hw);
  77         unsigned long flags;
  78         unsigned int status;
  79
  80         spin_lock_irqsave(gck->lock, flags);
  81         regmap_write(gck->regmap, gck->layout->offset,
  82                      (gck->id & gck->layout->pid_mask));
  83         regmap_read(gck->regmap, gck->layout->offset, &status);
  84         spin_unlock_irqrestore(gck->lock, flags);
  85
  86         return status & AT91_PMC_PCR_GCKEN ? 1 : 0;
  87 }
  88
  89 static unsigned long
  90 clk_generated_recalc_rate(struct clk_hw *hw,
  91                           unsigned long parent_rate)
  92 {
  93         struct clk_generated *gck = to_clk_generated(hw);
  94
  95         return DIV_ROUND_CLOSEST(parent_rate, gck->gckdiv + 1);
  96 }
  97
  98 static void clk_generated_best_diff(struct clk_rate_request *req,
  99                                     struct clk_hw *parent,
 100                                     unsigned long parent_rate, u32 div,
 101                                     int *best_diff, long *best_rate)
 102 {
 103         unsigned long tmp_rate;
 104         int tmp_diff;
 105
 106         if (!div)
 107                 tmp_rate = parent_rate;
 108         else
 109                 tmp_rate = parent_rate / div;
 110         tmp_diff = abs(req->rate - tmp_rate);
 111
 112         if (*best_diff < 0 || *best_diff > tmp_diff) {
 113                 *best_rate = tmp_rate;
 114                 *best_diff = tmp_diff;
 115                 req->best_parent_rate = parent_rate;
 116                 req->best_parent_hw = parent;
 117         }
 118 }
 119
 120 static int clk_generated_determine_rate(struct clk_hw *hw,
 121                                         struct clk_rate_request *req)
 122 {
 123         struct clk_generated *gck = to_clk_generated(hw);
 124         struct clk_hw *parent = NULL;
 125         struct clk_rate_request req_parent = *req;
 126         long best_rate = -EINVAL;
 127         unsigned long min_rate, parent_rate;
 128         int best_diff = -1;
 129         int i;
 130         u32 div;
 131
 132         for (i = 0; i < clk_hw_get_num_parents(hw) - 1; i++) {
 133                 parent = clk_hw_get_parent_by_index(hw, i);
 134                 if (!parent)
 135                         continue;
 136
 137                 parent_rate = clk_hw_get_rate(parent);
 138                 min_rate = DIV_ROUND_CLOSEST(parent_rate, GENERATED_MAX_DIV + 1);
 139                 if (!parent_rate ||
 140                     (gck->range.max && min_rate > gck->range.max))
 141                         continue;
 142
 143                 div = DIV_ROUND_CLOSEST(parent_rate, req->rate);
 144                 if (div > GENERATED_MAX_DIV + 1)
 145                         div = GENERATED_MAX_DIV + 1;
 146
 147                 clk_generated_best_diff(req, parent, parent_rate, div,
 148                                         &best_diff, &best_rate);
 149
 150                 if (!best_diff)
 151                         break;
 152         }
 153
 154         /*
 155          * The audio_pll rate can be modified, unlike the five others clocks
 156          * that should never be altered.
 157          * The audio_pll can technically be used by multiple consumers. However,
 158          * with the rate locking, the first consumer to enable to clock will be
 159          * the one definitely setting the rate of the clock.
 160          * Since audio IPs are most likely to request the same rate, we enforce
 161          * that the only clks able to modify gck rate are those of audio IPs.
 162          */
 163
 164         if (!gck->audio_pll_allowed)
 165                 goto end;
 166
 167         parent = clk_hw_get_parent_by_index(hw, GCK_INDEX_DT_AUDIO_PLL);
 168         if (!parent)
 169                 goto end;
 170
 171         for (div = 1; div < GENERATED_MAX_DIV + 2; div++) {
 172                 req_parent.rate = req->rate * div;
 173                 __clk_determine_rate(parent, &req_parent);
 174                 clk_generated_best_diff(req, parent, req_parent.rate, div,
 175                                         &best_diff, &best_rate);
 176
 177                 if (!best_diff)
 178                         break;
 179         }
 180
 181 end:
 182         pr_debug("GCLK: %s, best_rate = %ld, parent clk: %s @ %ld\n",
 183                  __func__, best_rate,
 184                  __clk_get_name((req->best_parent_hw)->clk),
 185                  req->best_parent_rate);
 186
 187         if (best_rate < 0)
 188                 return best_rate;
 189
 190         req->rate = best_rate;
 191         return 0;
 192 }
 193
 194 /* No modification of hardware as we have the flag CLK_SET_PARENT_GATE set */
 195 static int clk_generated_set_parent(struct clk_hw *hw, u8 index)
 196 {
 197         struct clk_generated *gck = to_clk_generated(hw);
 198
 199         if (index >= clk_hw_get_num_parents(hw))
 200                 return -EINVAL;
 201
 202         gck->parent_id = index;
 203         return 0;
 204 }
 205
 206 static u8 clk_generated_get_parent(struct clk_hw *hw)
 207 {
 208         struct clk_generated *gck = to_clk_generated(hw);
 209
 210         return gck->parent_id;
 211 }
 212
 213 /* No modification of hardware as we have the flag CLK_SET_RATE_GATE set */
 214 static int clk_generated_set_rate(struct clk_hw *hw,
 215                                   unsigned long rate,
 216                                   unsigned long parent_rate)
 217 {
 218         struct clk_generated *gck = to_clk_generated(hw);
 219         u32 div;
 220
 221         if (!rate)
 222                 return -EINVAL;
 223
 224         if (gck->range.max && rate > gck->range.max)
 225                 return -EINVAL;
 226
 227         div = DIV_ROUND_CLOSEST(parent_rate, rate);
 228         if (div > GENERATED_MAX_DIV + 1 || !div)
 229                 return -EINVAL;
 230
 231         gck->gckdiv = div - 1;
 232         return 0;
 233 }
 234
 235 static const struct clk_ops generated_ops = {
 236         .enable = clk_generated_enable,
 237         .disable = clk_generated_disable,
 238         .is_enabled = clk_generated_is_enabled,
 239         .recalc_rate = clk_generated_recalc_rate,
 240         .determine_rate = clk_generated_determine_rate,
 241         .get_parent = clk_generated_get_parent,
 242         .set_parent = clk_generated_set_parent,
 243         .set_rate = clk_generated_set_rate,
 244 };
 245
 246 /**
 247  * clk_generated_startup - Initialize a given clock to its default parent and
 248  * divisor parameter.
 249  *
 250  * @gck:        Generated clock to set the startup parameters for.
 251  *
 252  * Take parameters from the hardware and update local clock configuration
 253  * accordingly.
 254  */
 255 static void clk_generated_startup(struct clk_generated *gck)
 256 {
 257         u32 tmp;
 258         unsigned long flags;
 259
 260         spin_lock_irqsave(gck->lock, flags);
 261         regmap_write(gck->regmap, gck->layout->offset,
 262                      (gck->id & gck->layout->pid_mask));
 263         regmap_read(gck->regmap, gck->layout->offset, &tmp);
 264         spin_unlock_irqrestore(gck->lock, flags);
 265
 266         gck->parent_id = field_get(gck->layout->gckcss_mask, tmp);
 267         gck->gckdiv = FIELD_GET(AT91_PMC_PCR_GCKDIV_MASK, tmp);
 268 }
 269
 270 struct clk_hw * __init
 271 at91_clk_register_generated(struct regmap *regmap, spinlock_t *lock,
 272                             const struct clk_pcr_layout *layout,
 273                             const char *name, const char **parent_names,
 274                             u8 num_parents, u8 id, bool pll_audio,
 275                             const struct clk_range *range)
 276 {
 277         struct clk_generated *gck;
 278         struct clk_init_data init;
 279         struct clk_hw *hw;
 280         int ret;
 281
 282         gck = kzalloc(sizeof(*gck), GFP_KERNEL);
 283         if (!gck)
 284                 return ERR_PTR(-ENOMEM);
 285
 286         init.name = name;
 287         init.ops = &generated_ops;
 288         init.parent_names = parent_names;
 289         init.num_parents = num_parents;
 290         init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE |
 291                 CLK_SET_RATE_PARENT;
 292
 293         gck->id = id;
 294         gck->hw.init = &init;
 295         gck->regmap = regmap;
 296         gck->lock = lock;
 297         gck->range = *range;
 298         gck->audio_pll_allowed = pll_audio;
 299         gck->layout = layout;
 300
 301         clk_generated_startup(gck);
 302         hw = &gck->hw;
 303         ret = clk_hw_register(NULL, &gck->hw);
 304         if (ret) {
 305                 kfree(gck);
 306                 hw = ERR_PTR(ret);
 307         } else {
 308                 pmc_register_id(id);
 309         }
 310
 311         return hw;
 312 }