drivers/clk/clk-fixed-rate.c

   1 /*
   2  * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
   3  * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Fixed rate clock implementation
  10  */
  11
  12 #include <linux/clk-provider.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/io.h>
  16 #include <linux/err.h>
  17 #include <linux/of.h>
  18
  19 /*
  20  * DOC: basic fixed-rate clock that cannot gate
  21  *
  22  * Traits of this clock:
  23  * prepare - clk_(un)prepare only ensures parents are prepared
  24  * enable - clk_enable only ensures parents are enabled
  25  * rate - rate is always a fixed value.  No clk_set_rate support
  26  * parent - fixed parent.  No clk_set_parent support
  27  */
  28
  29 static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
  30                 unsigned long parent_rate)
  31 {
  32         return to_clk_fixed_rate(hw)->fixed_rate;
  33 }
  34
  35 static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
  36                 unsigned long parent_accuracy)
  37 {
  38         return to_clk_fixed_rate(hw)->fixed_accuracy;
  39 }
  40
  41 const struct clk_ops clk_fixed_rate_ops = {
  42         .recalc_rate = clk_fixed_rate_recalc_rate,
  43         .recalc_accuracy = clk_fixed_rate_recalc_accuracy,
  44 };
  45 EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
  46
  47 /**
  48  * clk_register_fixed_rate_with_accuracy - register fixed-rate clock with the
  49  *                                         clock framework
  50  * @dev: device that is registering this clock
  51  * @name: name of this clock
  52  * @parent_name: name of clock's parent
  53  * @flags: framework-specific flags
  54  * @fixed_rate: non-adjustable clock rate
  55  * @fixed_accuracy: non-adjustable clock rate
  56  */
  57 struct clk *clk_register_fixed_rate_with_accuracy(struct device *dev,
  58                 const char *name, const char *parent_name, unsigned long flags,
  59                 unsigned long fixed_rate, unsigned long fixed_accuracy)
  60 {
  61         struct clk_fixed_rate *fixed;
  62         struct clk *clk;
  63         struct clk_init_data init;
  64
  65         /* allocate fixed-rate clock */
  66         fixed = kzalloc(sizeof(*fixed), GFP_KERNEL);
  67         if (!fixed)
  68                 return ERR_PTR(-ENOMEM);
  69
  70         init.name = name;
  71         init.ops = &clk_fixed_rate_ops;
  72         init.flags = flags | CLK_IS_BASIC;
  73         init.parent_names = (parent_name ? &parent_name: NULL);
  74         init.num_parents = (parent_name ? 1 : 0);
  75
  76         /* struct clk_fixed_rate assignments */
  77         fixed->fixed_rate = fixed_rate;
  78         fixed->fixed_accuracy = fixed_accuracy;
  79         fixed->hw.init = &init;
  80
  81         /* register the clock */
  82         clk = clk_register(dev, &fixed->hw);
  83         if (IS_ERR(clk))
  84                 kfree(fixed);
  85
  86         return clk;
  87 }
  88 EXPORT_SYMBOL_GPL(clk_register_fixed_rate_with_accuracy);
  89
  90 /**
  91  * clk_register_fixed_rate - register fixed-rate clock with the clock framework
  92  * @dev: device that is registering this clock
  93  * @name: name of this clock
  94  * @parent_name: name of clock's parent
  95  * @flags: framework-specific flags
  96  * @fixed_rate: non-adjustable clock rate
  97  */
  98 struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
  99                 const char *parent_name, unsigned long flags,
 100                 unsigned long fixed_rate)
 101 {
 102         return clk_register_fixed_rate_with_accuracy(dev, name, parent_name,
 103                                                      flags, fixed_rate, 0);
 104 }
 105 EXPORT_SYMBOL_GPL(clk_register_fixed_rate);
 106
 107 void clk_unregister_fixed_rate(struct clk *clk)
 108 {
 109         struct clk_hw *hw;
 110
 111         hw = __clk_get_hw(clk);
 112         if (!hw)
 113                 return;
 114
 115         clk_unregister(clk);
 116         kfree(to_clk_fixed_rate(hw));
 117 }
 118 EXPORT_SYMBOL_GPL(clk_unregister_fixed_rate);
 119
 120 #ifdef CONFIG_OF
 121 /**
 122  * of_fixed_clk_setup() - Setup function for simple fixed rate clock
 123  */
 124 void of_fixed_clk_setup(struct device_node *node)
 125 {
 126         struct clk *clk;
 127         const char *clk_name = node->name;
 128         u32 rate;
 129         u32 accuracy = 0;
 130
 131         if (of_property_read_u32(node, "clock-frequency", &rate))
 132                 return;
 133
 134         of_property_read_u32(node, "clock-accuracy", &accuracy);
 135
 136         of_property_read_string(node, "clock-output-names", &clk_name);
 137
 138         clk = clk_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
 139                                                     0, rate, accuracy);
 140         if (!IS_ERR(clk))
 141                 of_clk_add_provider(node, of_clk_src_simple_get, clk);
 142 }
 143 EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
 144 CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);
 145 #endif