kernel/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 #define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)
  30
  31 static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
  32                 unsigned long parent_rate)
  33 {
  34         return to_clk_fixed_rate(hw)->fixed_rate;
  35 }
  36
  37 static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
  38                 unsigned long parent_accuracy)
  39 {
  40         return to_clk_fixed_rate(hw)->fixed_accuracy;
  41 }
  42
  43 const struct clk_ops clk_fixed_rate_ops = {
  44         .recalc_rate = clk_fixed_rate_recalc_rate,
  45         .recalc_accuracy = clk_fixed_rate_recalc_accuracy,
  46 };
  47 EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
  48
  49 /**
  50  * clk_register_fixed_rate_with_accuracy - register fixed-rate clock with the
  51  *                                         clock framework
  52  * @dev: device that is registering this clock
  53  * @name: name of this clock
  54  * @parent_name: name of clock's parent
  55  * @flags: framework-specific flags
  56  * @fixed_rate: non-adjustable clock rate
  57  * @fixed_accuracy: non-adjustable clock rate
  58  */
  59 struct clk *clk_register_fixed_rate_with_accuracy(struct device *dev,
  60                 const char *name, const char *parent_name, unsigned long flags,
  61                 unsigned long fixed_rate, unsigned long fixed_accuracy)
  62 {
  63         struct clk_fixed_rate *fixed;
  64         struct clk *clk;
  65         struct clk_init_data init;
  66
  67         /* allocate fixed-rate clock */
  68         fixed = kzalloc(sizeof(struct clk_fixed_rate), GFP_KERNEL);
  69         if (!fixed) {
  70                 pr_err("%s: could not allocate fixed clk\n", __func__);
  71                 return ERR_PTR(-ENOMEM);
  72         }
  73
  74         init.name = name;
  75         init.ops = &clk_fixed_rate_ops;
  76         init.flags = flags | CLK_IS_BASIC;
  77         init.parent_names = (parent_name ? &parent_name: NULL);
  78         init.num_parents = (parent_name ? 1 : 0);
  79
  80         /* struct clk_fixed_rate assignments */
  81         fixed->fixed_rate = fixed_rate;
  82         fixed->fixed_accuracy = fixed_accuracy;
  83         fixed->hw.init = &init;
  84
  85         /* register the clock */
  86         clk = clk_register(dev, &fixed->hw);
  87         if (IS_ERR(clk))
  88                 kfree(fixed);
  89
  90         return clk;
  91 }
  92 EXPORT_SYMBOL_GPL(clk_register_fixed_rate_with_accuracy);
  93
  94 /**
  95  * clk_register_fixed_rate - register fixed-rate clock with the clock framework
  96  * @dev: device that is registering this clock
  97  * @name: name of this clock
  98  * @parent_name: name of clock's parent
  99  * @flags: framework-specific flags
 100  * @fixed_rate: non-adjustable clock rate
 101  */
 102 struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
 103                 const char *parent_name, unsigned long flags,
 104                 unsigned long fixed_rate)
 105 {
 106         return clk_register_fixed_rate_with_accuracy(dev, name, parent_name,
 107                                                      flags, fixed_rate, 0);
 108 }
 109 EXPORT_SYMBOL_GPL(clk_register_fixed_rate);
 110
 111 #ifdef CONFIG_OF
 112 /**
 113  * of_fixed_clk_setup() - Setup function for simple fixed rate clock
 114  */
 115 void of_fixed_clk_setup(struct device_node *node)
 116 {
 117         struct clk *clk;
 118         const char *clk_name = node->name;
 119         u32 rate;
 120         u32 accuracy = 0;
 121
 122         if (of_property_read_u32(node, "clock-frequency", &rate))
 123                 return;
 124
 125         of_property_read_u32(node, "clock-accuracy", &accuracy);
 126
 127         of_property_read_string(node, "clock-output-names", &clk_name);
 128
 129         clk = clk_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
 130                                                     CLK_IS_ROOT, rate,
 131                                                     accuracy);
 132         if (!IS_ERR(clk))
 133                 of_clk_add_provider(node, of_clk_src_simple_get, clk);
 134 }
 135 EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
 136 CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);
 137 #endif