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 clk_factor, hw)
  26 struct clk_factor {
  27         struct clk_hw           hw;
  28         void __iomem            *base;
  29         struct clk_factor_masks *masks;
  30         struct clk_factor_tbl   *ftbl;
  31         unsigned int            ftbl_cnt;
  32 };
  33
  34 static long clk_factor_round_rate(struct clk_hw *hw, unsigned long drate,
  35                 unsigned long *prate)
  36 {
  37         struct clk_factor *factor = to_clk_factor(hw);
  38         unsigned long rate = 0, prev_rate;
  39         int i;
  40
  41         for (i = 0; i < factor->ftbl_cnt; i++) {
  42                 prev_rate = rate;
  43                 rate = (((*prate / 10000) * factor->ftbl[i].den) /
  44                         (factor->ftbl[i].num * factor->masks->factor)) * 10000;
  45                 if (rate > drate)
  46                         break;
  47         }
  48         if ((i == 0) || (i == factor->ftbl_cnt)) {
  49                 return rate;
  50         } else {
  51                 if ((drate - prev_rate) > (rate - drate))
  52                         return rate;
  53                 else
  54                         return prev_rate;
  55         }
  56 }
  57
  58 static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
  59                 unsigned long parent_rate)
  60 {
  61         struct clk_factor *factor = to_clk_factor(hw);
  62         struct clk_factor_masks *masks = factor->masks;
  63         unsigned int val, num, den;
  64
  65         val = readl_relaxed(factor->base);
  66
  67         /* calculate numerator */
  68         num = (val >> masks->num_shift) & masks->num_mask;
  69
  70         /* calculate denominator */
  71         den = (val >> masks->den_shift) & masks->den_mask;
  72
  73         if (!den)
  74                 return 0;
  75
  76         return (((parent_rate / 10000)  * den) /
  77                         (num * factor->masks->factor)) * 10000;
  78 }
  79
  80 /* Configures new clock rate*/
  81 static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
  82                                 unsigned long prate)
  83 {
  84         struct clk_factor *factor = to_clk_factor(hw);
  85         struct clk_factor_masks *masks = factor->masks;
  86         int i;
  87         unsigned long val;
  88         unsigned long prev_rate, rate = 0;
  89
  90         for (i = 0; i < factor->ftbl_cnt; i++) {
  91                 prev_rate = rate;
  92                 rate = (((prate / 10000) * factor->ftbl[i].den) /
  93                         (factor->ftbl[i].num * factor->masks->factor)) * 10000;
  94                 if (rate > drate)
  95                         break;
  96         }
  97         if (i > 0)
  98                 i--;
  99
 100         val = readl_relaxed(factor->base);
 101
 102         val &= ~(masks->num_mask << masks->num_shift);
 103         val |= (factor->ftbl[i].num & masks->num_mask) << masks->num_shift;
 104
 105         val &= ~(masks->den_mask << masks->den_shift);
 106         val |= (factor->ftbl[i].den & masks->den_mask) << masks->den_shift;
 107
 108         writel_relaxed(val, factor->base);
 109
 110         return 0;
 111 }
 112
 113 static struct clk_ops clk_factor_ops = {
 114         .recalc_rate = clk_factor_recalc_rate,
 115         .round_rate = clk_factor_round_rate,
 116         .set_rate = clk_factor_set_rate,
 117 };
 118
 119 struct clk *mmp_clk_register_factor(const char *name, const char *parent_name,
 120                 unsigned long flags, void __iomem *base,
 121                 struct clk_factor_masks *masks, struct clk_factor_tbl *ftbl,
 122                 unsigned int ftbl_cnt)
 123 {
 124         struct clk_factor *factor;
 125         struct clk_init_data init;
 126         struct clk *clk;
 127
 128         if (!masks) {
 129                 pr_err("%s: must pass a clk_factor_mask\n", __func__);
 130                 return ERR_PTR(-EINVAL);
 131         }
 132
 133         factor = kzalloc(sizeof(*factor), GFP_KERNEL);
 134         if (!factor) {
 135                 pr_err("%s: could not allocate factor  clk\n", __func__);
 136                 return ERR_PTR(-ENOMEM);
 137         }
 138
 139         /* struct clk_aux assignments */
 140         factor->base = base;
 141         factor->masks = masks;
 142         factor->ftbl = ftbl;
 143         factor->ftbl_cnt = ftbl_cnt;
 144         factor->hw.init = &init;
 145
 146         init.name = name;
 147         init.ops = &clk_factor_ops;
 148         init.flags = flags;
 149         init.parent_names = &parent_name;
 150         init.num_parents = 1;
 151
 152         clk = clk_register(NULL, &factor->hw);
 153         if (IS_ERR_OR_NULL(clk))
 154                 kfree(factor);
 155
 156         return clk;
 157 }