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].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
  54static 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*/
  77static 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
 109static 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
 115struct 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}
 154