drivers/clk/mmp/clk-frac.c

   1 /*
   2  * mmp factor clock operation source file
   3  *
   4  * Copyright (C) 2012 Marvell
   5  * Chao Xie <xiechao.mail@gmail.com>
   6  *
   7  * This file is licensed under the terms of the GNU General Public
   8  * License version 2. This program is licensed "as is" without any
   9  * warranty of any kind, whether express or implied.
  10  */
  11
  12 #include <linux/clk-provider.h>
  13 #include <linux/slab.h>
  14 #include <linux/io.h>
  15 #include <linux/err.h>
  16
  17 #include "clk.h"
  18 /*
  19  * It is M/N clock
  20  *
  21  * Fout from synthesizer can be given from two equations:
  22  * numerator/denominator = Fin / (Fout * factor)
  23  */
  24
  25 #define to_clk_factor(hw) container_of(hw, struct mmp_clk_factor, hw)
  26
  27 static long clk_factor_round_rate(struct clk_hw *hw, unsigned long drate,
  28                 unsigned long *prate)
  29 {
  30         struct mmp_clk_factor *factor = to_clk_factor(hw);
  31         u64 rate = 0, prev_rate;
  32         int i;
  33
  34         for (i = 0; i < factor->ftbl_cnt; i++) {
  35                 prev_rate = rate;
  36                 rate = *prate;
  37                 rate *= factor->ftbl[i].den;
  38                 do_div(rate, factor->ftbl[i].num * factor->masks->factor);
  39
  40                 if (rate > drate)
  41                         break;
  42         }
  43         if ((i == 0) || (i == factor->ftbl_cnt)) {
  44                 return rate;
  45         } else {
  46                 if ((drate - prev_rate) > (rate - drate))
  47                         return rate;
  48                 else
  49                         return prev_rate;
  50         }
  51 }
  52
  53 static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
  54                 unsigned long parent_rate)
  55 {
  56         struct mmp_clk_factor *factor = to_clk_factor(hw);
  57         struct mmp_clk_factor_masks *masks = factor->masks;
  58         unsigned int val, num, den;
  59         u64 rate;
  60
  61         val = readl_relaxed(factor->base);
  62
  63         /* calculate numerator */
  64         num = (val >> masks->num_shift) & masks->num_mask;
  65
  66         /* calculate denominator */
  67         den = (val >> masks->den_shift) & masks->den_mask;
  68
  69         if (!den)
  70                 return 0;
  71
  72         rate = parent_rate;
  73         rate *= den;
  74         do_div(rate, num * factor->masks->factor);
  75
  76         return rate;
  77 }
  78
  79 /* Configures new clock rate*/
  80 static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
  81                                 unsigned long prate)
  82 {
  83         struct mmp_clk_factor *factor = to_clk_factor(hw);
  84         struct mmp_clk_factor_masks *masks = factor->masks;
  85         int i;
  86         unsigned long val;
  87         unsigned long flags = 0;
  88         u64 rate = 0;
  89
  90         for (i = 0; i < factor->ftbl_cnt; i++) {
  91                 rate = prate;
  92                 rate *= factor->ftbl[i].den;
  93                 do_div(rate, factor->ftbl[i].num * factor->masks->factor);
  94
  95                 if (rate > drate)
  96                         break;
  97         }
  98         if (i > 0)
  99                 i--;
 100
 101         if (factor->lock)
 102                 spin_lock_irqsave(factor->lock, flags);
 103
 104         val = readl_relaxed(factor->base);
 105
 106         val &= ~(masks->num_mask << masks->num_shift);
 107         val |= (factor->ftbl[i].num & masks->num_mask) << masks->num_shift;
 108
 109         val &= ~(masks->den_mask << masks->den_shift);
 110         val |= (factor->ftbl[i].den & masks->den_mask) << masks->den_shift;
 111
 112         writel_relaxed(val, factor->base);
 113
 114         if (factor->lock)
 115                 spin_unlock_irqrestore(factor->lock, flags);
 116
 117         return 0;
 118 }
 119
 120 static int clk_factor_init(struct clk_hw *hw)
 121 {
 122         struct mmp_clk_factor *factor = to_clk_factor(hw);
 123         struct mmp_clk_factor_masks *masks = factor->masks;
 124         u32 val, num, den;
 125         int i;
 126         unsigned long flags = 0;
 127
 128         if (factor->lock)
 129                 spin_lock_irqsave(factor->lock, flags);
 130
 131         val = readl(factor->base);
 132
 133         /* calculate numerator */
 134         num = (val >> masks->num_shift) & masks->num_mask;
 135
 136         /* calculate denominator */
 137         den = (val >> masks->den_shift) & masks->den_mask;
 138
 139         for (i = 0; i < factor->ftbl_cnt; i++)
 140                 if (den == factor->ftbl[i].den && num == factor->ftbl[i].num)
 141                         break;
 142
 143         if (i >= factor->ftbl_cnt) {
 144                 val &= ~(masks->num_mask << masks->num_shift);
 145                 val |= (factor->ftbl[0].num & masks->num_mask) <<
 146                         masks->num_shift;
 147
 148                 val &= ~(masks->den_mask << masks->den_shift);
 149                 val |= (factor->ftbl[0].den & masks->den_mask) <<
 150                         masks->den_shift;
 151         }
 152
 153         if (!(val & masks->enable_mask) || i >= factor->ftbl_cnt) {
 154                 val |= masks->enable_mask;
 155                 writel(val, factor->base);
 156         }
 157
 158         if (factor->lock)
 159                 spin_unlock_irqrestore(factor->lock, flags);
 160
 161         return 0;
 162 }
 163
 164 static const struct clk_ops clk_factor_ops = {
 165         .recalc_rate = clk_factor_recalc_rate,
 166         .round_rate = clk_factor_round_rate,
 167         .set_rate = clk_factor_set_rate,
 168         .init = clk_factor_init,
 169 };
 170
 171 struct clk *mmp_clk_register_factor(const char *name, const char *parent_name,
 172                 unsigned long flags, void __iomem *base,
 173                 struct mmp_clk_factor_masks *masks,
 174                 struct mmp_clk_factor_tbl *ftbl,
 175                 unsigned int ftbl_cnt, spinlock_t *lock)
 176 {
 177         struct mmp_clk_factor *factor;
 178         struct clk_init_data init;
 179         struct clk *clk;
 180
 181         if (!masks) {
 182                 pr_err("%s: must pass a clk_factor_mask\n", __func__);
 183                 return ERR_PTR(-EINVAL);
 184         }
 185
 186         factor = kzalloc(sizeof(*factor), GFP_KERNEL);
 187         if (!factor)
 188                 return ERR_PTR(-ENOMEM);
 189
 190         /* struct clk_aux assignments */
 191         factor->base = base;
 192         factor->masks = masks;
 193         factor->ftbl = ftbl;
 194         factor->ftbl_cnt = ftbl_cnt;
 195         factor->hw.init = &init;
 196         factor->lock = lock;
 197
 198         init.name = name;
 199         init.ops = &clk_factor_ops;
 200         init.flags = flags;
 201         init.parent_names = &parent_name;
 202         init.num_parents = 1;
 203
 204         clk = clk_register(NULL, &factor->hw);
 205         if (IS_ERR_OR_NULL(clk))
 206                 kfree(factor);
 207
 208         return clk;
 209 }