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].num) /
  44                         (factor->ftbl[i].den * factor->masks->factor)) * 10000;
  45                 if (rate > drate)
  46                         break;
  47         }
  48         if (i == 0)
  49                 return rate;
  50         else
  51                 return prev_rate;
  52 }
  53
  54 static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
  55                 unsigned long parent_rate)
  56 {
  57         struct clk_factor *factor = to_clk_factor(hw);
  58         struct clk_factor_masks *masks = factor->masks;
  59         unsigned int val, num, den;
  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->num_mask;
  68
  69         if (!den)
  70                 return 0;
  71
  72         return (((parent_rate / 10000)  * den) /
  73                         (num * factor->masks->factor)) * 10000;
  74 }
  75
  76 /* Configures new clock rate*/
  77 static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
  78                                 unsigned long prate)
  79 {
  80         struct clk_factor *factor = to_clk_factor(hw);
  81         struct clk_factor_masks *masks = factor->masks;
  82         int i;
  83         unsigned long val;
  84         unsigned long prev_rate, rate = 0;
  85
  86         for (i = 0; i < factor->ftbl_cnt; i++) {
  87                 prev_rate = rate;
  88                 rate = (((prate / 10000) * factor->ftbl[i].num) /
  89                         (factor->ftbl[i].den * factor->masks->factor)) * 10000;
  90                 if (rate > drate)
  91                         break;
  92         }
  93         if (i > 0)
  94                 i--;
  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         return 0;
 107 }
 108
 109 static struct clk_ops clk_factor_ops = {
 110         .recalc_rate = clk_factor_recalc_rate,
 111         .round_rate = clk_factor_round_rate,
 112         .set_rate = clk_factor_set_rate,
 113 };
 114
 115 struct clk *mmp_clk_register_factor(const char *name, const char *parent_name,
 116                 unsigned long flags, void __iomem *base,
 117                 struct clk_factor_masks *masks, struct clk_factor_tbl *ftbl,
 118                 unsigned int ftbl_cnt)
 119 {
 120         struct clk_factor *factor;
 121         struct clk_init_data init;
 122         struct clk *clk;
 123
 124         if (!masks) {
 125                 pr_err("%s: must pass a clk_factor_mask\n", __func__);
 126                 return ERR_PTR(-EINVAL);
 127         }
 128
 129         factor = kzalloc(sizeof(*factor), GFP_KERNEL);
 130         if (!factor) {
 131                 pr_err("%s: could not allocate factor  clk\n", __func__);
 132                 return ERR_PTR(-ENOMEM);
 133         }
 134
 135         /* struct clk_aux assignments */
 136         factor->base = base;
 137         factor->masks = masks;
 138         factor->ftbl = ftbl;
 139         factor->ftbl_cnt = ftbl_cnt;
 140         factor->hw.init = &init;
 141
 142         init.name = name;
 143         init.ops = &clk_factor_ops;
 144         init.flags = flags;
 145         init.parent_names = &parent_name;
 146         init.num_parents = 1;
 147
 148         clk = clk_register(NULL, &factor->hw);
 149         if (IS_ERR_OR_NULL(clk))
 150                 kfree(factor);
 151
 152         return clk;
 153 }