LXR linux/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)
  26struct 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
  34static 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
  58static 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*/
  81static 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
 113static 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
 119struct 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}
 158