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 #include <linux/of.h>
  15
  16 /*
  17  * DOC: basic fixed multiplier and divider clock that cannot gate
  18  *
  19  * Traits of this clock:
  20  * prepare - clk_prepare only ensures that parents are prepared
  21  * enable - clk_enable only ensures that parents are enabled
  22  * rate - rate is fixed.  clk->rate = parent->rate / div * mult
  23  * parent - fixed parent.  No clk_set_parent support
  24  */
  25
  26 #define to_clk_fixed_factor(_hw) container_of(_hw, struct clk_fixed_factor, hw)
  27
  28 static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
  29                 unsigned long parent_rate)
  30 {
  31         struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
  32         unsigned long long int rate;
  33
  34         rate = (unsigned long long int)parent_rate * fix->mult;
  35         do_div(rate, fix->div);
  36         return (unsigned long)rate;
  37 }
  38
  39 static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
  40                                 unsigned long *prate)
  41 {
  42         struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
  43
  44         if (__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT) {
  45                 unsigned long best_parent;
  46
  47                 best_parent = (rate / fix->mult) * fix->div;
  48                 *prate = __clk_round_rate(__clk_get_parent(hw->clk),
  49                                 best_parent);
  50         }
  51
  52         return (*prate / fix->div) * fix->mult;
  53 }
  54
  55 static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate,
  56                                 unsigned long parent_rate)
  57 {
  58         /*
  59          * We must report success but we can do so unconditionally because
  60          * clk_factor_round_rate returns values that ensure this call is a
  61          * nop.
  62          */
  63
  64         return 0;
  65 }
  66
  67 const struct clk_ops clk_fixed_factor_ops = {
  68         .round_rate = clk_factor_round_rate,
  69         .set_rate = clk_factor_set_rate,
  70         .recalc_rate = clk_factor_recalc_rate,
  71 };
  72 EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);
  73
  74 struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
  75                 const char *parent_name, unsigned long flags,
  76                 unsigned int mult, unsigned int div)
  77 {
  78         struct clk_fixed_factor *fix;
  79         struct clk_init_data init;
  80         struct clk *clk;
  81
  82         fix = kmalloc(sizeof(*fix), GFP_KERNEL);
  83         if (!fix)
  84                 return ERR_PTR(-ENOMEM);
  85
  86         /* struct clk_fixed_factor assignments */
  87         fix->mult = mult;
  88         fix->div = div;
  89         fix->hw.init = &init;
  90
  91         init.name = name;
  92         init.ops = &clk_fixed_factor_ops;
  93         init.flags = flags | CLK_IS_BASIC;
  94         init.parent_names = &parent_name;
  95         init.num_parents = 1;
  96
  97         clk = clk_register(dev, &fix->hw);
  98
  99         if (IS_ERR(clk))
 100                 kfree(fix);
 101
 102         return clk;
 103 }
 104 EXPORT_SYMBOL_GPL(clk_register_fixed_factor);
 105
 106 #ifdef CONFIG_OF
 107 /**
 108  * of_fixed_factor_clk_setup() - Setup function for simple fixed factor clock
 109  */
 110 void __init of_fixed_factor_clk_setup(struct device_node *node)
 111 {
 112         struct clk *clk;
 113         const char *clk_name = node->name;
 114         const char *parent_name;
 115         u32 div, mult;
 116
 117         if (of_property_read_u32(node, "clock-div", &div)) {
 118                 pr_err("%s Fixed factor clock <%s> must have a clock-div property\n",
 119                         __func__, node->name);
 120                 return;
 121         }
 122
 123         if (of_property_read_u32(node, "clock-mult", &mult)) {
 124                 pr_err("%s Fixed factor clock <%s> must have a clock-mult property\n",
 125                         __func__, node->name);
 126                 return;
 127         }
 128
 129         of_property_read_string(node, "clock-output-names", &clk_name);
 130         parent_name = of_clk_get_parent_name(node, 0);
 131
 132         clk = clk_register_fixed_factor(NULL, clk_name, parent_name, 0,
 133                                         mult, div);
 134         if (!IS_ERR(clk))
 135                 of_clk_add_provider(node, of_clk_src_simple_get, clk);
 136 }
 137 EXPORT_SYMBOL_GPL(of_fixed_factor_clk_setup);
 138 CLK_OF_DECLARE(fixed_factor_clk, "fixed-factor-clock",
 139                 of_fixed_factor_clk_setup);
 140 #endif