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 EXPORT_SYMBOL_GPL(clk_fixed_rate_recalc_rate);
  36
  37 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 struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
  43                 const char *parent_name, unsigned long flags,
  44                 unsigned long fixed_rate)
  45 {
  46         struct clk_fixed_rate *fixed;
  47         char **parent_names = NULL;
  48         u8 len;
  49
  50         fixed = kzalloc(sizeof(struct clk_fixed_rate), GFP_KERNEL);
  51
  52         if (!fixed) {
  53                 pr_err("%s: could not allocate fixed clk\n", __func__);
  54                 return ERR_PTR(-ENOMEM);
  55         }
  56
  57         /* struct clk_fixed_rate assignments */
  58         fixed->fixed_rate = fixed_rate;
  59
  60         if (parent_name) {
  61                 parent_names = kmalloc(sizeof(char *), GFP_KERNEL);
  62
  63                 if (! parent_names)
  64                         goto out;
  65
  66                 len = sizeof(char) * strlen(parent_name);
  67
  68                 parent_names[0] = kmalloc(len, GFP_KERNEL);
  69
  70                 if (!parent_names[0])
  71                         goto out;
  72
  73                 strncpy(parent_names[0], parent_name, len);
  74         }
  75
  76 out:
  77         return clk_register(dev, name,
  78                         &clk_fixed_rate_ops, &fixed->hw,
  79                         parent_names,
  80                         (parent_name ? 1 : 0),
  81                         flags);
  82 }