drivers/clk/clk-fixed-factor.c

   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
  27 static 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
  32         return parent_rate * fix->mult / fix->div;
  33 }
  34
  35 static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
  36                                 unsigned long *prate)
  37 {
  38         struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
  39
  40         if (__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT) {
  41                 unsigned long best_parent;
  42
  43                 best_parent = (rate / fix->mult) * fix->div;
  44                 *prate = __clk_round_rate(__clk_get_parent(hw->clk),
  45                                 best_parent);
  46         }
  47
  48         return (*prate / fix->div) * fix->mult;
  49 }
  50
  51 static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate,
  52                                 unsigned long parent_rate)
  53 {
  54         return 0;
  55 }
  56
  57 struct clk_ops clk_fixed_factor_ops = {
  58         .round_rate = clk_factor_round_rate,
  59         .set_rate = clk_factor_set_rate,
  60         .recalc_rate = clk_factor_recalc_rate,
  61 };
  62 EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);
  63
  64 struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
  65                 const char *parent_name, unsigned long flags,
  66                 unsigned int mult, unsigned int div)
  67 {
  68         struct clk_fixed_factor *fix;
  69         struct clk_init_data init;
  70         struct clk *clk;
  71
  72         fix = kmalloc(sizeof(*fix), GFP_KERNEL);
  73         if (!fix) {
  74                 pr_err("%s: could not allocate fixed factor clk\n", __func__);
  75                 return ERR_PTR(-ENOMEM);
  76         }
  77
  78         /* struct clk_fixed_factor assignments */
  79         fix->mult = mult;
  80         fix->div = div;
  81         fix->hw.init = &init;
  82
  83         init.name = name;
  84         init.ops = &clk_fixed_factor_ops;
  85         init.flags = flags;
  86         init.parent_names = &parent_name;
  87         init.num_parents = 1;
  88
  89         clk = clk_register(dev, &fix->hw);
  90
  91         if (IS_ERR(clk))
  92                 kfree(fix);
  93
  94         return clk;
  95 }