linux/drivers/clk/clk-fixed-factor.c
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   1/*
   2 * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * Standard functionality for the common clock API.
   9 */
  10#include <linux/module.h>
  11#include <linux/clk-provider.h>
  12#include <linux/slab.h>
  13#include <linux/err.h>
  14
  15/*
  16 * DOC: basic fixed multiplier and divider clock that cannot gate
  17 *
  18 * Traits of this clock:
  19 * prepare - clk_prepare only ensures that parents are prepared
  20 * enable - clk_enable only ensures that parents are enabled
  21 * rate - rate is fixed.  clk->rate = parent->rate / div * mult
  22 * parent - fixed parent.  No clk_set_parent support
  23 */
  24
  25#define to_clk_fixed_factor(_hw) container_of(_hw, struct clk_fixed_factor, hw)
  26
  27static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
  28                unsigned long parent_rate)
  29{
  30        struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
  31        unsigned long long int rate;
  32
  33        rate = (unsigned long long int)parent_rate * fix->mult;
  34        do_div(rate, fix->div);
  35        return (unsigned long)rate;
  36}
  37
  38static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
  39                                unsigned long *prate)
  40{
  41        struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
  42
  43        if (__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT) {
  44                unsigned long best_parent;
  45
  46                best_parent = (rate / fix->mult) * fix->div;
  47                *prate = __clk_round_rate(__clk_get_parent(hw->clk),
  48                                best_parent);
  49        }
  50
  51        return (*prate / fix->div) * fix->mult;
  52}
  53
  54static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate,
  55                                unsigned long parent_rate)
  56{
  57        return 0;
  58}
  59
  60struct clk_ops clk_fixed_factor_ops = {
  61        .round_rate = clk_factor_round_rate,
  62        .set_rate = clk_factor_set_rate,
  63        .recalc_rate = clk_factor_recalc_rate,
  64};
  65EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);
  66
  67struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
  68                const char *parent_name, unsigned long flags,
  69                unsigned int mult, unsigned int div)
  70{
  71        struct clk_fixed_factor *fix;
  72        struct clk_init_data init;
  73        struct clk *clk;
  74
  75        fix = kmalloc(sizeof(*fix), GFP_KERNEL);
  76        if (!fix) {
  77                pr_err("%s: could not allocate fixed factor clk\n", __func__);
  78                return ERR_PTR(-ENOMEM);
  79        }
  80
  81        /* struct clk_fixed_factor assignments */
  82        fix->mult = mult;
  83        fix->div = div;
  84        fix->hw.init = &init;
  85
  86        init.name = name;
  87        init.ops = &clk_fixed_factor_ops;
  88        init.flags = flags | CLK_IS_BASIC;
  89        init.parent_names = &parent_name;
  90        init.num_parents = 1;
  91
  92        clk = clk_register(dev, &fix->hw);
  93
  94        if (IS_ERR(clk))
  95                kfree(fix);
  96
  97        return clk;
  98}
  99
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