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         unsigned long rate = 0, prev_rate;
  32         int i;
  33
  34         for (i = 0; i < factor->ftbl_cnt; i++) {
  35                 prev_rate = rate;
  36                 rate = (((*prate / 10000) * factor->ftbl[i].den) /
  37                         (factor->ftbl[i].num * factor->masks->factor)) * 10000;
  38                 if (rate > drate)
  39                         break;
  40         }
  41         if ((i == 0) || (i == factor->ftbl_cnt)) {
  42                 return rate;
  43         } else {
  44                 if ((drate - prev_rate) > (rate - drate))
  45                         return rate;
  46                 else
  47                         return prev_rate;
  48         }
  49 }
  50
  51 static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
  52                 unsigned long parent_rate)
  53 {
  54         struct mmp_clk_factor *factor = to_clk_factor(hw);
  55         struct mmp_clk_factor_masks *masks = factor->masks;
  56         unsigned int val, num, den;
  57
  58         val = readl_relaxed(factor->base);
  59
  60         /* calculate numerator */
  61         num = (val >> masks->num_shift) & masks->num_mask;
  62
  63         /* calculate denominator */
  64         den = (val >> masks->den_shift) & masks->den_mask;
  65
  66         if (!den)
  67                 return 0;
  68
  69         return (((parent_rate / 10000)  * den) /
  70                         (num * factor->masks->factor)) * 10000;
  71 }
  72
  73 /* Configures new clock rate*/
  74 static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
  75                                 unsigned long prate)
  76 {
  77         struct mmp_clk_factor *factor = to_clk_factor(hw);
  78         struct mmp_clk_factor_masks *masks = factor->masks;
  79         int i;
  80         unsigned long val;
  81         unsigned long rate = 0;
  82         unsigned long flags = 0;
  83
  84         for (i = 0; i < factor->ftbl_cnt; i++) {
  85                 rate = (((prate / 10000) * factor->ftbl[i].den) /
  86                         (factor->ftbl[i].num * factor->masks->factor)) * 10000;
  87                 if (rate > drate)
  88                         break;
  89         }
  90         if (i > 0)
  91                 i--;
  92
  93         if (factor->lock)
  94                 spin_lock_irqsave(factor->lock, flags);
  95
  96         val = readl_relaxed(factor->base);
  97
  98         val &= ~(masks->num_mask << masks->num_shift);
  99         val |= (factor->ftbl[i].num & masks->num_mask) << masks->num_shift;
 100
 101         val &= ~(masks->den_mask << masks->den_shift);
 102         val |= (factor->ftbl[i].den & masks->den_mask) << masks->den_shift;
 103
 104         writel_relaxed(val, factor->base);
 105
 106         if (factor->lock)
 107                 spin_unlock_irqrestore(factor->lock, flags);
 108
 109         return 0;
 110 }
 111
 112 static int clk_factor_init(struct clk_hw *hw)
 113 {
 114         struct mmp_clk_factor *factor = to_clk_factor(hw);
 115         struct mmp_clk_factor_masks *masks = factor->masks;
 116         u32 val, num, den;
 117         int i;
 118         unsigned long flags = 0;
 119
 120         if (factor->lock)
 121                 spin_lock_irqsave(factor->lock, flags);
 122
 123         val = readl(factor->base);
 124
 125         /* calculate numerator */
 126         num = (val >> masks->num_shift) & masks->num_mask;
 127
 128         /* calculate denominator */
 129         den = (val >> masks->den_shift) & masks->den_mask;
 130
 131         for (i = 0; i < factor->ftbl_cnt; i++)
 132                 if (den == factor->ftbl[i].den && num == factor->ftbl[i].num)
 133                         break;
 134
 135         if (i >= factor->ftbl_cnt) {
 136                 val &= ~(masks->num_mask << masks->num_shift);
 137                 val |= (factor->ftbl[0].num & masks->num_mask) <<
 138                         masks->num_shift;
 139
 140                 val &= ~(masks->den_mask << masks->den_shift);
 141                 val |= (factor->ftbl[0].den & masks->den_mask) <<
 142                         masks->den_shift;
 143
 144                 writel(val, factor->base);
 145         }
 146
 147         if (factor->lock)
 148                 spin_unlock_irqrestore(factor->lock, flags);
 149
 150         return 0;
 151 }
 152
 153 static const struct clk_ops clk_factor_ops = {
 154         .recalc_rate = clk_factor_recalc_rate,
 155         .round_rate = clk_factor_round_rate,
 156         .set_rate = clk_factor_set_rate,
 157         .init = clk_factor_init,
 158 };
 159
 160 struct clk *mmp_clk_register_factor(const char *name, const char *parent_name,
 161                 unsigned long flags, void __iomem *base,
 162                 struct mmp_clk_factor_masks *masks,
 163                 struct mmp_clk_factor_tbl *ftbl,
 164                 unsigned int ftbl_cnt, spinlock_t *lock)
 165 {
 166         struct mmp_clk_factor *factor;
 167         struct clk_init_data init;
 168         struct clk *clk;
 169
 170         if (!masks) {
 171                 pr_err("%s: must pass a clk_factor_mask\n", __func__);
 172                 return ERR_PTR(-EINVAL);
 173         }
 174
 175         factor = kzalloc(sizeof(*factor), GFP_KERNEL);
 176         if (!factor)
 177                 return ERR_PTR(-ENOMEM);
 178
 179         /* struct clk_aux assignments */
 180         factor->base = base;
 181         factor->masks = masks;
 182         factor->ftbl = ftbl;
 183         factor->ftbl_cnt = ftbl_cnt;
 184         factor->hw.init = &init;
 185         factor->lock = lock;
 186
 187         init.name = name;
 188         init.ops = &clk_factor_ops;
 189         init.flags = flags;
 190         init.parent_names = &parent_name;
 191         init.num_parents = 1;
 192
 193         clk = clk_register(NULL, &factor->hw);
 194         if (IS_ERR_OR_NULL(clk))
 195                 kfree(factor);
 196
 197         return clk;
 198 }