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
  18 /*
  19  * DOC: basic fixed-rate clock that cannot gate
  20  *
  21  * Traits of this clock:
  22  * prepare - clk_(un)prepare only ensures parents are prepared
  23  * enable - clk_enable only ensures parents are enabled
  24  * rate - rate is always a fixed value.  No clk_set_rate support
  25  * parent - fixed parent.  No clk_set_parent support
  26  */
  27
  28 #define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)
  29
  30 static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
  31                 unsigned long parent_rate)
  32 {
  33         return to_clk_fixed_rate(hw)->fixed_rate;
  34 }
  35
  36 const struct clk_ops clk_fixed_rate_ops = {
  37         .recalc_rate = clk_fixed_rate_recalc_rate,
  38 };
  39 EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
  40
  41 /**
  42  * clk_register_fixed_rate - register fixed-rate clock with the clock framework
  43  * @dev: device that is registering this clock
  44  * @name: name of this clock
  45  * @parent_name: name of clock's parent
  46  * @flags: framework-specific flags
  47  * @fixed_rate: non-adjustable clock rate
  48  */
  49 struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
  50                 const char *parent_name, unsigned long flags,
  51                 unsigned long fixed_rate)
  52 {
  53         struct clk_fixed_rate *fixed;
  54         struct clk *clk;
  55         struct clk_init_data init;
  56
  57         /* allocate fixed-rate clock */
  58         fixed = kzalloc(sizeof(struct clk_fixed_rate), GFP_KERNEL);
  59         if (!fixed) {
  60                 pr_err("%s: could not allocate fixed clk\n", __func__);
  61                 return ERR_PTR(-ENOMEM);
  62         }
  63
  64         init.name = name;
  65         init.ops = &clk_fixed_rate_ops;
  66         init.flags = flags;
  67         init.parent_names = (parent_name ? &parent_name: NULL);
  68         init.num_parents = (parent_name ? 1 : 0);
  69
  70         /* struct clk_fixed_rate assignments */
  71         fixed->fixed_rate = fixed_rate;
  72         fixed->hw.init = &init;
  73
  74         /* register the clock */
  75         clk = clk_register(dev, &fixed->hw);
  76
  77         if (IS_ERR(clk))
  78                 kfree(fixed);
  79
  80         return clk;
  81 }