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 const struct clk_ops clk_fixed_rate_ops = {
  38         .recalc_rate = clk_fixed_rate_recalc_rate,
  39 };
  40 EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
  41
  42 /**
  43  * clk_register_fixed_rate - register fixed-rate clock with the clock framework
  44  * @dev: device that is registering this clock
  45  * @name: name of this clock
  46  * @parent_name: name of clock's parent
  47  * @flags: framework-specific flags
  48  * @fixed_rate: non-adjustable clock rate
  49  */
  50 struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
  51                 const char *parent_name, unsigned long flags,
  52                 unsigned long fixed_rate)
  53 {
  54         struct clk_fixed_rate *fixed;
  55         struct clk *clk;
  56         struct clk_init_data init;
  57
  58         /* allocate fixed-rate clock */
  59         fixed = kzalloc(sizeof(struct clk_fixed_rate), GFP_KERNEL);
  60         if (!fixed) {
  61                 pr_err("%s: could not allocate fixed clk\n", __func__);
  62                 return ERR_PTR(-ENOMEM);
  63         }
  64
  65         init.name = name;
  66         init.ops = &clk_fixed_rate_ops;
  67         init.flags = flags | CLK_IS_BASIC;
  68         init.parent_names = (parent_name ? &parent_name: NULL);
  69         init.num_parents = (parent_name ? 1 : 0);
  70
  71         /* struct clk_fixed_rate assignments */
  72         fixed->fixed_rate = fixed_rate;
  73         fixed->hw.init = &init;
  74
  75         /* register the clock */
  76         clk = clk_register(dev, &fixed->hw);
  77
  78         if (IS_ERR(clk))
  79                 kfree(fixed);
  80
  81         return clk;
  82 }
  83 EXPORT_SYMBOL_GPL(clk_register_fixed_rate);
  84
  85 #ifdef CONFIG_OF
  86 /**
  87  * of_fixed_clk_setup() - Setup function for simple fixed rate clock
  88  */
  89 void of_fixed_clk_setup(struct device_node *node)
  90 {
  91         struct clk *clk;
  92         const char *clk_name = node->name;
  93         u32 rate;
  94
  95         if (of_property_read_u32(node, "clock-frequency", &rate))
  96                 return;
  97
  98         of_property_read_string(node, "clock-output-names", &clk_name);
  99
 100         clk = clk_register_fixed_rate(NULL, clk_name, NULL, CLK_IS_ROOT, rate);
 101         if (!IS_ERR(clk))
 102                 of_clk_add_provider(node, of_clk_src_simple_get, clk);
 103 }
 104 EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
 105 CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);
 106 #endif